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  • Evolution  (44)
  • Triticum aestivum
  • phosphorus
  • Springer  (121)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • 2005-2009
  • 1990-1994  (121)
  • 1980-1984
  • 1994  (121)
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  • 2005-2009
  • 1990-1994  (121)
  • 1980-1984
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  • 1
    Electronic Resource
    Electronic Resource
    On the possible role of montmorillonites in prebiotic peptide formation (1994)
    Springer
    Monatshefte für Chemie 125 (1994), S. 1033-1039 
    Details
    ISSN: 1434-4475
    Keywords: Prebiotic peptide formation ; Evolution ; Clay catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Fähigkeit von Tonmineralien der Montmorillonitklasse zur Katalyse von Peptidbildungsreaktionen aus Aminosäuren in wäßriger Lösung wurde am Beispiel von Glyzin und Kupfer sowie Kalzium und Morillonit untersucht. Experimente mit Verdampfungszyklen haben gezeigt, daß kleinere Mengen von Di- und Tripeptiden aus der Aminosäure gebildet werden. Die weitere Polymerisation von Dipeptiden hingegen scheint wesentlich leichter in diesem Reaktionssystem zu verlaufen als der Anfangsschritt der Bildung des Dipeptides. Eine mögliche Rolle von Tonmineralien in der präbiotischen Peptidevolution kann daher in der Verlängerung von Peptidketten gesehen werden. Kupferionen in der Tonmatrix zeigen keinerlei Vorteile gegenüber den üblichen Kalziumionen, die in natürlichem Montmorillonit vorkommen.
    Notes: Summary The ability of montmorillonite clay minerals for catalyzing peptide formation from amino acids in aqueous solution has been investigated using glycine and Cu2+ and Ca2+ containing montmorillonites as reaction systems. Evaporation cycle experiments showed that minor amounts of di- and tripeptide are formed from the amino acid. Further polymerization of dipeptide, however, seems to be more favoured by this reaction system than the initial step of dipeptide formation, and a possible role of clays in prebiotic peptide evolution could be seen therefore in the prolongation of peptide chains. Cu2+ ions in the clay matrix did not show any advantage over the usual Ca2+ ions embedded in natural montmorillonite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811510
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  • 2
    Electronic Resource
    Electronic Resource
    Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff (1994)
    Springer
    Bulletin of volcanology 56 (1994), S. 377-385 
    Details
    ISSN: 1432-0819
    Keywords: Key wordsZoned magma body ; Chemical variation ; ash-flow sheets ; Tephra sequence ; Differentiation ; time constraints ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2– one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55–66% SiO2) and a high silica (〉66% SiO2) trend. Ninety per cent of the Rainier Mesa sheet occurs in the high silica trend. Immediately beneath the Rainier Mesa sheet is a thick tephra sequence. The chemical variation of this sequence is nearly equivalent to the high silica portion of the Rainier Mesa ash-flow sheet (about 66–78% SiO2). Throughout the tephra sequence numerous small ash-flow layers occur, and each ash-flow layer is chemically zoned from more evolved at the base to less evolved at the top. This is consistent with having been erupted from a zoned magma body. The lowest silica tephra units are at the base of the sequence and the highest silica units are at the top – that is, the large-scale chemical trend of the entire sequence is opposite to that of the individual ash-flow layers. These ash-flow layers are of very small volume. The tephra sequence provides a unique record of the incremental development of the zoned, high silica portion of the Rainier Mesa magma body.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326463
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular evolution of the HSP70 multigene family (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 1-17 
    Details
    ISSN: 1432-1432
    Keywords: HSP70 ; Heat shock ; Evolution ; Phylogeny ; Yeast ; Multigene family ; Subcellular compartmentalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eukaryotic genomes encode multiple 70-kDa heat-shock proteins (HSP70s). The Saccharomyces cerevisiae HSP70 family is comprised of eight members. Here we present the nucleotide sequence of the SSA3 and SSB2 genes, completing the nucleotide sequence data for the yeast HSP70 family. We have analyzed these yeast sequences as well as 29 HSP70s from 24 additional eukaryotic and prokaryotic species. Comparison of the sequences demonstrates the extreme conservation of HSP70s; proteins from the most distantly related species share at least 45% identity and more than one-sixth of the amino acids are identical in the aligned region (567 amino acids) among all proteins analyzed. Phylogenetic trees constructed by two independent methods indicate that ancient molecular and cellular events have given rise to at least four monophyletic groups of eukaryotic HSP70 proteins. Each group of evolutionarily similar HSP70s shares a common intracellular localization and is presumed to be comprised of functional homologues; these include heat-shock proteins of the cytoplasm, endoplasmic reticulum, mitochondria, and chloroplasts. HSP70s localized in mitochondria and plastids are most similar to the DnaK HSP70 homologues in purple bacteria and cyanobacteria, respectively, which is consistent with the proposed prokaryotic origin of these organelles. The analyses indicate that the major eukaryotic HSP70 groups arose prior to the divergence of the earliest eukaryotes, roughly 2 billion years ago. In some cases, as exemplified by the SSA genes encoding the cytoplasmic HSP70s of S. cerevisiae, more recent duplication events have given rise to subfamilies within the major groups. The S. cerevisiae SSB proteins comprise a unique subfamily not identified in other species to date. This subfamily appears to have resulted from an ancient gene duplication that occurred at approximately the same time as the origin of the major eukaryotic HSP70 groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175490
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of a species-specific satellite DNA family of Dolichopoda schiavazzii (Orthoptera, Rhaphidophoridae) cave crickets (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 274-281 
    Details
    ISSN: 1432-1432
    Keywords: Repetitive DNA ; Tandem repeats ; Sequence analysis ; Recombination ; Isolated populations ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The satellite DNA family pDoP102 is species specific for the cave cricket Dolichopoda schiavazzii, an endemic species of mainland and insular Tuscany. It consists of numerous tandemly arranged repeats, 102 bp in length, and evolved most probably after cladogenesis of D. schiavazzii from the D. baccettii-aegilion group within the last 2.3 ± 0.8 million years. A sequence comparison of 31 clones (53 repetition units) from three isolated populations reveals a very high degree of sequence homogeneity within the species with no evidence for any specific population features. This appears to be in contrast to the results of allozyme analyses which account for a relatively old evolutionary divergence of the Elba island population from the mainland ones. Since the assumption of actual gene flow and recent colonization is rejected, the observed sequence homogeneity is hypothesized to be maintained by recombination processes preventing fixation of newly introduced mutations on pDoP102 sequence clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160151
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of two abundant satellite DNAs from the mealworm Tenebrio obscurus (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 489-495 
    Details
    ISSN: 1432-1432
    Keywords: Repetitive sequences ; Sequence variability ; Evolution ; Heterochromatin ; DNA curvature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two highly abundant satellite DNAs comprise 36% of the Tenebrio obscurus (Tenebrionidae, Coleoptera) genome. They are designated as satellite I and satellite II with the monomer length of 344 and 142 base pairs (bp), respectively. Both satellites differ in their nucleotide (nt) sequences, but the frequency of point mutations, well-conserved length of monomer variants, stretches of shared mutations characteristic for the process of gene conversion, and distribution of both satellites in regions of centromeric heterochromatin of all chromosomes indicate that the same evolutionary processes act on both of them with the same, or similar, rate. While satellite I shares no sequence similarity with any other known nt sequence, satellite II is 79.7% homologous with the highly abundant satellite from closely related Tenebrio molitor. Difference in the frequency of point mutations and absence of shared mutations indicating gene conversion strongly suggest that in these two closely related species mutational processes affecting satellite DNAs seem to be changed. Retarded electrophoretic mobility, due to sequence-induced curvature of DNA helix axis, was observed for T. obscurus satellite II, but not for satellite I. Although evolutionary processes act with different rates in T. obscurus and T. molitor satellites the monomer length and sequence-induced curvature are well preserved in both 142-bp satellites, as well as in, at the nt sequence level completely divergent, Palorus ratzeburgii (Tenebrionidae) satellite, indicating potential importance of these parameters in their evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173418
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  • 6
    Electronic Resource
    Electronic Resource
    Convergent evolution of crystallin gene regulation in squid and chicken: The AP-1/ARE connection (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 134-143 
    Details
    ISSN: 1432-1432
    Keywords: Lens ; Crystallin ; Squid ; Chicken ; Gene ; Regulation ; AP-1 ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous experiments have shown that the minimal promoters required for function of the squid SL20-1 and SL11 crystallin genes in transfected rabbit lens epithelial cells contain an overlapping AP-1/antioxidant responsive element (ARE) upstream of the TATA box. This region resembles the PL-1 and PL-2 elements of the chicken βB 1-cry stallin promoter which are essential for promoter function in transfected primary chicken lens epithelial cells. Here we demonstrate by site-directed mutagenesis that the AP-1/ARE sequence is essential for activity of the squid SL20-1 and SL11 promoters in transfected embryonic chicken lens cells and fibroblasts. Promoter activity was higher in transfected lens cells than in fibroblasts. Electrophoretic mobility shift and DNase protection experiments demonstrated the formation of numerous complexes between nuclear proteins of the embryonic chicken lens and the AP-1/ARE sequences of the squid SL20-1 and SL11 crystallin promoters. One of these complexes comigrated and cross-competed with that formed with the PL-1 element of the chicken βB1-crystallin promoter. This complex formed with nuclear extracts from the lens, heart, brain, and skeletal muscle of embryonic chickens and was eliminated by competition with a consensus AP-1 sequence. The nonfunctional mutant AP-1/ ARE sequences did not compete for complex formation. These data raise the intriguing possibility that entirely different, nonhomologous crystallin genes of the chicken and squid have convergently evolved a similar cis-acting regulatory element (AP-1/ARE) for high expression in the lens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163802
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  • 7
    Electronic Resource
    Electronic Resource
    Conservation of human Y chromosome sequences among male great apes: Implications for the evolution of Y chromosomes (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 13-21 
    Details
    ISSN: 1432-1432
    Keywords: Y chromosome ; Great ape ; Human ; Evolution ; DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nine newly described single-copy and lowcopy-number genomic DNA sequences isolated from a flow-sorted human Y chromosome library were mapped to regions of the human Y chromosome and were hybridized to Southern blots of male and female great ape genomic DNAs (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus). Eight of the nine sequences mapped to the euchromatic Y long arm (Yq) in humans, and the ninth mapped to the short arm or pericentromeric region. All nine of the newly identified sequences and two additional human Yq sequences hybridized to restriction fragments in male but not female genomic DNA from the great apes, indicating Y chromosome localization. Seven of these 11 human Yq sequences hybridized to similarly-sized restriction endonuclease fragments in all the great ape species analyzed. The five human sequences that mapped to the most distal subregion of Yq (deletion of which region is associated with spermatogenic failure in humans) were hybridized to Southern blots generated by pulsed-field gel electrophoresis. These sequences define a region of approximately 1 Mb on human Yq in which HpaII tiny fragment (HTF) islands appear to be absent. The conservation of these human Yq sequences on great ape Y chromosomes indicates a greater stability in this region of the Y than has been previously described for most anonymous human Y chromosomal sequences. The stability of these sequences on great ape Y chromosomes seems remarkable given that this region of the Y does not undergo meiotic recombination and the sequences do not appear to encode genes for which positive selection might occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00178245
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  • 8
    Electronic Resource
    Electronic Resource
    Did neural pooling for night vision lead to the evolution of neural superposition eyes? (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 289-302 
    Details
    ISSN: 1432-1351
    Keywords: Compound eye ; Open rhabdom ; Neural superposition ; Visual ecology ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Observations of the infrared deep pseudopupil, optical determinations of the corneal nodal point, and histological methods were used to relate the visual fields of individual rhabdomeres to the array of ommatidial optical axes in four insects with open rhabdoms: the tenebrionid beetle Zophobas morio, the earwig Forficula auricularia, the crane fly Tipula pruinosa, and the backswimmer Notonecta glauca. The open rhabdoms of all four species have a central pair of rhabdomeres surrounded by six peripheral rhabdomeres. At night, a distal pigment aperture is fully open and the rhabdom receives light over an angle approximately six times the interommatidial angle. Different rhabdomeres within the same ommatidium do not share the same visual axis, and the visual fields of the peripheral rhabdomeres overlap the optical axes of several near-by ommatidia. During the day, the pigment aperture is considerably smaller, and all rhabdomeres share the same visual field of about two interommatidial angles, or less, depending on the degree of light adaptation. The pigment aperture serves two functions: (1) it allows the circadian rhythm to switch between the night and day sampling patterns, and (2) it works as a light driven pupil during the day. Theoretical considerations suggest that, in the night eye, the peripheral retinula cells are involved in neural pooling in the lamina, with asymmetric pooling fields matching the visual fields of the rhabdomeres. Such a system provides high sensitivity for nocturnal vision, and the open rhabdom has the potential of feeding information into parallel spatial channels with different tradeoffs between resolution and sensitivity. Modification of this operational principle to suit a strictly diurnal life, makes the contractile pigment aperture superfluous, and decreasing angular sensitivities together with decreasing pooling fields lead to a neural superposition eye.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192988
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  • 9
    Electronic Resource
    Electronic Resource
    Cloning and characterization of the platypus mitochondrial genome (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 200-205 
    Details
    ISSN: 1432-1432
    Keywords: Evolution ; Monotreme ; Platypus ; mtDNA ; tRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vertebrate mitochondrial genome is highly conserved in size and gene content. Among the chordates there appears to be one basic gene arrangement, but rearrangements in the mitochondrial gene order of the avian lineages have indicated that the mitochondrial genome may be more variable than once thought. Different gene orders in marsupials and eutherian mammals leave the ancestral mammalian order in some doubt. We have investigated the mitochondrial gene order in the platypus (Ornithorhynchus anatinus), a representative of the third major group of mammals, to determine which mitochondrial gene arrangement is ancestral in mammals. We have found that the platypus mtDNA conforms to the basic chordate gene arrangement, common to fish, amphibians, and eutherian mammals, indicating that this arrangement was the original mammalian arrangement, and that the unusual rearrangements observed in the avians and marsupials are probably lineage-specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163808
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  • 10
    Electronic Resource
    Electronic Resource
    Interspecific sequence comparison of the muscle-myosin heavy-chain genes from Drosophila hydei and Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 357-368 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Muscle-myosin heavy-chain gene ; Alternative exons ; Synonymous substitutions ; Amino acid substitutions ; Evolution ; Testis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The muscle-myosin heavy-chain (mMHC) gene of Drosophila hydei has been sequenced completely (size 23.3 kb). The sequence comparison with the D. melanogaster mMHC gene revealed that the exonintron pattern is identical. The protein coding regions show a high degree of conservation (97%). The alternatively spliced exons (3a-b, 7a-d, 9a-c, 11a-e, and 15a-b) display more variations in the number of nonsynonymous and synonymous substitutions than the common exons (2, 4, 5, 6, 8, 10, 12, 13, 14, 16, 17, and 19). The base composition at synonymous sites of fourfold degenerate codons (third position) is not biased in the alternative exons. In the common exons there exists a bias for C and against A. These findings imply that the alternative exons of the Drosophila mMHC gene evolve at a different, in several cases higher, rate than the common ones. The 5′ splice junctions and 5′ and 3′ untranslated regions show a high level of similarity, indicating a functional constraint on these sequences. The intron regions vary considerably in length within one species, but the corresponding introns are very similar in length between the two species and all contain stretches of sequence similarity. A particular example is the first intron, which contains multiple regions of similarity. In the conserved regions of intron 12 (head-tail border) sequences were found which have the potential to direct another smaller mMHC transcript.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160268
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  • 11
    Electronic Resource
    Electronic Resource
    An analysis of retroposition in plants based on a family of SINEs from Brassica napus (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 378-386 
    Details
    ISSN: 1432-1432
    Keywords: CpG dinucleotides ; Evolution ; Repetitive sequences ; Reverse transcriptase ; S1Bn retroposons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The identification of a family of SINE retroposons dispersed in the genome of oilseed rape Brassica napus has provided the basis for an evolutionary analysis of retroposition in plants. The repetitive elements (called S1Bn) are 170 by long and occupy roughly 500 loci by haploid genome. They present characteristic features of SINE retroposons such as a 3′ terminal A-rich region, two conserved polymerase III motifs (box A and B), flanking direct repeats of variable sizes, and a primary and secondary sequence homology to several tRNA species. A consensus sequence was made from the alignment of 34 members of the family. The retroposon population was divided into five subfamilies based on several correlated sets of mutations from the consensus. These precise separations in subfamilies based on “diagnostic” mutations and the random distribution of mutations observed inside each subfamily are consistent with the master sequence model proposed for the dispersion of mammalian retroposons. An independent analysis of each subfamily provides strong evidence for the coexpression of at least three subfamily master sequences (SMS). In contrast to mammalian retroposition, diagnostic positions are not shared between SMS. We therefore propose that SMS were all derived from a general master sequence (GMS) and independently activated for retroposition after a variable period of random drift. Possible models for plant retroposition are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160270
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  • 12
    Electronic Resource
    Electronic Resource
    The sequence and expression pattern of the Calliphora erythrocephala yolk protein A and B genes (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 336-351 
    Details
    ISSN: 1432-1432
    Keywords: Yolk protein genes ; Vitellogenesis ; Calliphora ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The yolk protein genes (yps) are expressed in a temporal, tissue- and sex-specific fashion in Drosophila melanogaster. Here we report the sequence of two related genes in Calliphora erythrocephala. The predicted Calliphora yolk protein (YP) sequences are well conserved, especially at the C-terminal end when compared to those of D. melanogaster and Ceratitis capitata. Database searches with the Calliphora yolk protein B (CeYPB) sequence identify the vertebrate lipase similarity reported for the YPs of Drosophila and Ceratitis. Moreover, sequences with identity to divalent ion-binding sites were observed, which colocalized with putative tyrosine sulfation sites. Calliphora oogenesis differs from Drosophila in that it is cyclic in response to a meat feed. The Calliphora yp genes are expressed in the follicle cells of the egg chamber during vitellogenesis, as shown by in situ hybridization, and the yp message levels correlate with YP synthesis. The synthesis of the yp transcripts in ovaries of Calliphora occurs in the same pattern as that for ovarian transcripts in Drosophila. In the carcass, yp transcript levels are correlated with the production of a batch of eggs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163151
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  • 13
    Electronic Resource
    Electronic Resource
    Molecular phylogenies based on ribosomal protein L11, L1, L10, and L12 sequences (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 405-419 
    Details
    ISSN: 1432-1432
    Keywords: Molecular phylogeny ; Universal tree ; Ribosomal proteins ; Evolution ; Archaebacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Available sequences that correspond to the E. coli ribosomal proteins L11, L1, L10, and L12 from eubacteria, archaebacteria, and eukaryotes have been aligned. The alignments were analyzed qualitatively for shared structural features and for conservation of deletions or insertions. The alignments were further subjected to quantitative phylogenetic analysis, and the amino acid identity between selected pairs of sequences was calculated. In general, eubacteria, archaebacteria, and eukaryotes each form coherent and well-resolved nonoverlapping phylogenetic domains. The degree of diversity of the four proteins between the three groups is not uniform. For L11, the eubacterial and archaebacterial proteins are very similar whereas the eukaryotic L11 is clearly less similar. In contrast, in the case of the L12 proteins and to a lesser extent the L10 proteins, the archaebacterial and eukaryotic proteins are similar whereas the eubacterial proteins are different. The eukaryotic L1 equivalent protein has yet to be identified. If the root of the universal tree is near or within the eubacterial domain, our ribosomal protein-based phylogenies indicate that archaebacteria are monophyletic. The eukaryotic lineage appears to originate either near or within the archaebacterial domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163157
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  • 14
    Electronic Resource
    Electronic Resource
    Phylogeny and physiology of Drosophila opsins (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 250-262 
    Details
    ISSN: 1432-1432
    Keywords: Opsin ; Visual pigments ; Gene family ; Evolution ; Phylogeny ; Spectral sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic and physiological methods were used to study the evolution of the opsin gene family in Drosophila. A phylogeny based on DNA sequences from 13 opsin genes including representatives from the two major subgenera of Drosophila shows six major, well-supported clades: The “blue opsin” clade includes all of the Rhl and Rh2 genes and is separated into two distinct subclades of Rhl sequences and Rh2 sequences; the ultraviolet opsin clade includes all Rh3 and Rh4 genes and bifurcates into separate Rh3 and Rh4 clades. The duplications that generated this gene family most likely took place before the evolution of the subgenera Drosophila and Sophophora and their component species groups. Numerous changes have occurred in these genes since the duplications, including the loss and/or gain of introns in the different genes and even within the Rhl and Rh4 clades. Despite these changes, the spectral sensitivity of each of the opsins has remained remarkably fixed in a sample of four species representing two species groups in each of the two subgenera. All of the strains that were investigated had R1-6 (Rhl) spectral sensitivity curves that peaked at or near 480 nm, R7 (Rh3 and Rh4) peaks in the ultraviolet range, and ocellar (Rh2) peaks near 420 nm. Each of the four gene clades on the phylogeny exhibits very conservative patterns of amino acid replacement in domains of the protein thought to influence spectral sen sitivity, reflecting strong constraints on the spectrum of light visible to Drosophila.
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    URL: http://dx.doi.org/10.1007/BF00176087
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  • 15
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    Investigation of the human Rh blood group system in nonhuman primates and other species with serologic and Southern blot analysis (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 87-92 
    Details
    ISSN: 1432-1432
    Keywords: Rh blood group ; Evolution ; Rh antibodies ; Restriction fragments ; Primates ; Chimpanzee ; Gorilla ; New World monkey ; Old World monkey
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To investigate the evolution of the Rh blood-group system in anthropoid apes, New and Old World monkeys, and nonprimate animals, serologic typing of erythrocytes from these species with antibodies specific for the human Rh blood-group antigens was performed. In addition, genomic DNA from these animals was analyzed on Southern blots with a human Rh-specific cDNA. Consistent with earlier reports, serologic results showed that gorilla and chimpanzee erythrocytes had epitopes recognized by human Rh D and c antisera, and gibbon erythrocytes were recognized by the c antisera. Surprisingly, some Old and New World monkeys also expressed a Rh c epitope on their erythrocytes. No erythrocytes from the nonprimate animals reacted specifically with any of the human Rh antisera. Southern blot analysis with a human Rh-specific cDNA probe detected Rh-related sequences in anthropoid apes, all New and Old World monkeys, and in most nonprimate animals tested. Although some Rh-related restriction fragments were conserved across species lines in primates, the Rh locus was more polymorphic in chimpanzees and gorillas than in humans. In addition, restriction fragments segregating with the presence of the D antigen in humans were present in the primate species that expressed the D antigen.
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    URL: http://dx.doi.org/10.1007/BF00178253
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  • 16
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    A self-organised travelling salesman (1994)
    Springer
    Neural computing & applications 2 (1994), S. 129-133 
    Details
    ISSN: 1433-3058
    Keywords: Self-organisation ; Evolution ; Virtual-nodes ; Survival ; Simulated annealing ; Travelling salesman problem (TSP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Using the principles of self-organisation and Darwin's theory of evolution, an algorithm has been developed to solve the geometric travelling salesman problem (TSP). In this approach, we have virtual and real nodes (cities) which can have equal or different masses (weights). The virtual nodes and their neighours are attracted toward the fixed cities by a Newtonian force. The birth and death of the virtual nodes creates a world in which only the fittest survive. This approach has been successfully tested on many problems of different sizes, with a constant error of about 4.6% across the whole range. The computing time follows a power series (square law) versus the number of cities. Comparison of our results with those obtained by a simulated annealing method showed the solutions that obtained by this self-organisation method are of a better quality, especially for large size problems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415008
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  • 17
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    Historical changes in sediments of Pyramid Lake, Nevada, USA: consequences of changes in the water balance of a terminal desert lake (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 87-101 
    Details
    ISSN: 1573-0417
    Keywords: Great Basin ; climatic variations ; productivity ; organic matter ; nitrogen ; phosphorus ; hardwater lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from the shallow and deep basins of Pyramid Lake, Nevada, revealed variations in composition with depth reflecting changes in lake level, river inflow, and lake productivity. Recent sediments from the period of historical record indicate: (1) CaCO3 and organic content of sediment in the shallow basin decrease at lower lake level, (2) CaCO3 content of deep basin sediments increases when lake level decreases rapidly, and (3) the inorganic P content of sediments increases with decreasing lake volume. Variations in sediment composition also indicate several periods for which productivity in Pyramid Lake may have been elevated over the past 1000 years. Our data provide strong evidence for increased productivity during the first half of the 20th Century, although the typical pattern for cultural eutrophication was not observed. The organic content of sediments also suggests periods of increased productivity in the lake prior to the discovery and development of the region by white settlers. Indeed, a broad peak in organic fractions during the 1800's originates as an increase starting around 1600. However, periods of changing organic content of sediments also correspond to periods when inflow to the lake was probably at extremes (e.g. drought or flood) indicating that fluctuations in river inflow may be an important factor affecting sediment composition in Pyramid Lake.
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    URL: http://dx.doi.org/10.1007/BF00678089
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    Environmental impact of fertilizing soils by using sewage and animal wastes (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 1-22 
    Details
    ISSN: 1573-0867
    Keywords: animal slurries and manures ; applications to soils ; carbon- ; nitrogen- ; phosphorus ; contamination ; crop production ; dissemination ; hazardous organics ; heavy metals ; inputs ; macro- and micronutrients ; pathogens ; sewage sludges ; survival- ; transfer- ; transport and adsorption rates in soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The European Community is producing annually about 300 × 106 tons of sewage sludges as well as about 150, 950,160 and 200 tons of domestic, agricultural, industrial and other wastes (street litter, dead leaves etc.). About 20–25% of the German sewage sludges, which contain in average about 3.8,1.6, 0.4, 0.6, 5.3% DM−1 N, P, K, Mg and Ca, 202, 5, 131, 349, 53, 3 and 1446 mg kg−1 DM Pb, Cd, Cr, Cu, Ni, Hg, Zn as well as ca. 37 and 5 mg kg−1 Dm polychlorinated hydrocarbons and biphenyls, are recycled annually as fertilizer. In addition environmental impacts on the arable land of Germany may derive from 76,19.2, 64.7, 33.6, 7.8 and 0.1 kg ha−1 a−1 of N, P, K, Ca, Mg and Cu added as animal manures. Besides heavy metals and hazardous organics pathogens are disseminated with organic wastes. Crop production and soil fertility generally profit from the considerable amounts of plant nutrients and carbon in sewage sludges, animal slurries and manures, but the physicochemical soil properties, the composition of microbial, faunal and plant communities as well as the metabolic processes in the soil-, rhizo- and phyllosphere are changed by organic manuring. Consequences for the soil carbon-, nitrogen-and phosphorus-cycle are discussed. Impacts of heavy metals and hazardous organics on the soil biomass and its habitat as well as on transport mechanisms and surival times of disseminated pathogens in soils are reviewed with emphasis on the German situation. A proposal for future strategies (landscape recycling) is made.
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    URL: http://dx.doi.org/10.1007/BF00750669
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    Land application of poultry litter and water quality in Oklahoma, U.S.A. (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 165-173 
    Details
    ISSN: 1573-0867
    Keywords: Animal manure ; eutrophication ; ground water ; nitrogen ; phosphorus ; surface runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the rapid growth of the poultry industry in Oklahoma, U.S.A., more litter is applied to farm land. Thus, information is required on the impact of applications on regional soil and water resources. The effect of soil and poultry litter management on nitrogen (N) and phosphorus (P) loss in runoff and subsurface flow from four 16 m2 plots (Ruston fine sandy loam, 6 to 8% slope) was investigated under natural rainfall. Plots under Bermudagrass (Cynodon dactylon) received 11 Mg litter ha−1, which amounts to contributions of approximately 410 kg N and 140 kg P ha−1 yr−1. In spring, litter was broadcast on 3 of the plots; the upper half of one and total area of the other two. One of the total-area broadcast plots was tilled to 6 cm, the other remained as no till. The fourth plot served as a control. Relative to the control, litter application increased mean concentrations of total N and total P in runoff during the 16-week study for no-till (15.4 and 5.8 mg L−1) and tilled treatments (16.7 and 6.1 mg L−1). However, values for the half-area application (5.6 and 2.0 mg L−1) were similar to the control (5.7 and 1.3 mg L−1). Interflow (subsurface lateral flow at 70 cm depth) P was not affected by litter application; however, nitrate-N concentrations increased from 0.6 (control) to 2.9 mg L−1 (no till). In all cases, 〈 2 % litter N and P was lost in runoff and interflow, maintaining acceptable water quality concentrations. Although litter increased grass yield (8518 kg ha−1) compared to the control (3501 kg ha−1), yields were not affected by litter management. An 8-fold increase in the plant available P content of surface soil indicates long-term litter management and application rates will be critical to the environmentally sound use of this nutrient resource.
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    URL: http://dx.doi.org/10.1007/BF00750462
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    Response of ensete (Ensete ventricosum W.) to mineral fertilizers in southwest Ethiopia (1994)
    Springer
    Nutrient cycling in agroecosystems 37 (1994), S. 107-113 
    Details
    ISSN: 1573-0867
    Keywords: Ensete ventricosum ; fertilizer response ; nitrogen ; phosphorus ; potassium ; sulphur ; starch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ensete (Ensete ventricosum W. Cheesm.) is a root crop which stores starch in the root and in the lower part of the stem. It is grown in the southwest of Ethiopia and due to its drought resistance, it is of outstanding importance for the supply of food to the local population. Until now virtually nothing is known about the response of Ensete to fertilizer application. Field trials carried out on three representative soils in Ethiopia showed that Ensete biomass yields were increased significantly on all three soils by nitrogen and phosphorus application. Potassium had only marginal effect on biomass growth but favourably influenced starch production. Sulfate application had no major impact on growth and starch yield. The yield response was well related to the level of available nutrients in the soil, as determined by electroultrafiltration (EUF). Leaf analysis provided preliminary evidence that optimum levels of N, P, and K may be 3.8%, 0.3%, and 4.8%, respectively.
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    URL: http://dx.doi.org/10.1007/BF00748551
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  • 21
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    Effect of soil pH on the requirement for water-soluble phosphorus in triple superphosphate fertilizers (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 207-214 
    Details
    ISSN: 1573-0867
    Keywords: available P ; citrate insoluble P ; phosphorus sources ; triple superphosphate ; Triticum aestivum ; water soluble P ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse study was conducted to determine if soil pH affects the requirement for water-soluble P and the tolerance of water-insoluble impurities in TSP fertilizers. Two commercial TSP fertilizers were selected to represent a range in phosphate rock sources and impurities. Phosphate fertilizer impurities were isolated as the water-washed fraction by washing whole fertilizers with deionized water. TSP fertilizers with various quantities of water-soluble P (1.2 to 99% water-soluble P) were simulated by mixing the water-washed fertilizer fractions or dicalcium phosphate (DCP) with reagent-grade monocalcium phosphate (MCP). The fertilizers were applied to supply 40 mg AOAC available P kg−1 to a Mountview silt loam (fine-silty, siliceous, thermic Typic Paleudults). Wheat (Triticum aestivum (L.)) was harvested at 49 and 84 days after planting. Soil pH values at the final forage harvest were 5.4±0.16 and 6.4±0.15. At a soil pH of 5.4, the TSP fertilizers required only 37% water-soluble P to reach maximum yields while at pH 6.4 the fertilizers required 63% water-soluble P. Results of this study show that higher levels of water -insoluble P can be tolerated in TSP fertilizers when applied to acid soils. Phosphorus uptake was not affected by soil pH, but for the mixtures containing the fertilizer residues the source having the lowest level of Fe and Al had a higher relative agronomic effectiveness.
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    Effect of water supply on the response of wheat and triticale to applications of rock phosphate and superphosphate (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 43-57 
    Details
    ISSN: 1573-0867
    Keywords: Bicarbonate soil test phosphorus ; relative effectiveness ; rock phosphate ; superphosphate ; Triticum aestivum ; ×Triticosecale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of water supply on the response of wheat (Triticum aestivum) and triticale (×Triticosecale) to levels of freshly-applied rock phosphate and superphosphate, and the residues of these fertilizers applied 9 years previously in the field, was studied in three glasshouse experiments. The 〈 2 mm fraction of the top 10 cm of soil was used (1.8 kg soil per pot), and in one experiment, freshly-applied fertilizer was also added to the more acidic subsoil (10 to 20 cm). There were two water treatments: the soil was returned to field capacity by watering to weight, either daily (W1, adequate water) or weekly (W2, water stress). Yield of dried tops was used to calculate fertilizer effectiveness. The phosphorus (P) concentration in dried tops was used to determine critical P, which is the P concentration related to 90% of the maximum yield. Just before sowing, soil samples were collected to measure bicarbonate-extractable (soil test) P which was related to plant yield. Water stress reduced yields and maximum yield plateaus by 20 to 40%. Water stress reduced the effectiveness of all P fertilizers by between 20 to 60%, largely because of a reduction in the maximum yield potentials. In the field, water supply is seasonally dependent and it can affect the yield response of plants to freshly-applied rock phosphate and superphosphate and the residues of these fertilizers applied to the field in previous years. Relative to placing fertilizer in the topsoil, placing fertilizer in the subsoil improved effectiveness by about 26% for rock phosphate and 12% for superphosphate. The relationship between yield and P concentration in dried tops, and critical P, differed for W1 and W2. The soil test P calibration, which relates yield to soil test P, and the soil test P required to produce the same yield also differed for W1 and W2. Consequently critical P and soil test P calibrations depend on water supply, which in the field varies within and between growing seasons. This is so for freshly- and previously-applied rock phosphate and superphosphate.
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    URL: http://dx.doi.org/10.1007/BF00750156
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    Effect of phosphate on the sorption, desorption and plant-availability of selenium in soil (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 189-197 
    Details
    ISSN: 1573-0867
    Keywords: interaction ; isotopic exchange ; phosphorus ; plant-availability ; selenium ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Phosphate, applied at 5µg P cm−3, decreased selenite sorption by from 30–70% in three soils studied. Both maximum sorption (Xm) and the binding-energy of sorption as indicated by the binding-energy related constant (k) or the molar free energy (ΔG) of the sorption reaction derived from the Langmuir equation were considerably decreased. On the other hand, phosphate sorption was decreased by increasing concentration of selenite from 0.2µg Se cm−3 to 1.0µg Se cm−3 in the initial solution. The competitive sorption of phosphate with selenite was likely the main mechanism involved in the P-Se interactions. The competitively sorbed selenite exhibited much larger desorption in 0.01M CaCl2 solution, more readily extractable to 0.5M NaHCO3 and significantly higher isotopic exchangeability compared to that sorbed without the competing anion. Results from pot trial using ryegrass indicated that phosphate application increased more efficiently the plant-availability of applied fertilizer Se than that of indegeneous Se in soil.
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    URL: http://dx.doi.org/10.1007/BF00750246
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    Phosphorus and nitrogen limitation of algal biomass across trophic gradients (1994)
    Springer
    Aquatic sciences 56 (1994), S. 16-28 
    Details
    ISSN: 1420-9055
    Keywords: Chlorophyll-a ; phosphorus ; nitrogen ; lake ecosystem ; nutrient limitation ; regression analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Regression results based on data from 46 northern temperate lakes show that total phosphorus (TP) is the best predictor for phytoplankton (as chl-a) at lower trophic levels, TP 〈 200 mg · m−3. A regression including both TP and TN as regressors is the best predictor for lakes with TP 〉 200 mg · m−3. However, the good correlation is probably due to a high correlation between lake average chl-a (all years observed) and lake average TP and TN. Within single hypereutrophic lakes, TN alone is the best predictor. It was not possible to identify a medium trophic domain where TN and TP in combination was the best predictor for chl-a. The ratio TN:TP in the water decreases from about 40 to about 5 with increasing trophic level. Optimum TN:TP ratio for algal species with high abundance during late summer and autumn reflects this decreasing ratio, but within a lesser range, i.e., 20 to 5. In contrast, TN:TP ratios for species abundant during the early vernal period showed no, or an inverse, relation to the TN:TP ratio of the water.
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    URL: http://dx.doi.org/10.1007/BF00877432
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    Contribution of nitrogen and phosphorus by precipitation in the drainage basin of the Santillana Reservoir (Madrid) (1994)
    Springer
    Environmental geology 23 (1994), S. 99-104 
    Details
    ISSN: 1432-0495
    Keywords: Nitrogen ; phosphorus ; Precipitation collector ; Nutrients rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The contribution of nitrogen and phosphorus due to precipitation constitutes the second most important route after superficial runoff. The sampling carried out during a two-year period by means of a precipitation collector allows us to determine the contribution of this route both qualitatively and quantitatively. Nitrogen is mainly supplied in an inorganic form, while phosphorus is principally supplied as orthophosphate. During the period of this study (March 1986–February 1988) it was found that in the Santillana Reservoir Watershed the level of nitrogen supplied by precipitation constitutes an average of 4.87% and the level of phosphorus constitutes 8.01%. The contribution of nitrogen varies in inverse ratio to precipitation and the contribution of phosphorus varies in direct ratio.
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    URL: http://dx.doi.org/10.1007/BF00766982
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    Role of ooplasmic segregation in mammalian development (1994)
    Springer
    Development genes and evolution 203 (1994), S. 199-204 
    Details
    ISSN: 1432-041X
    Keywords: Cell differentiation ; Cytoplasm ; Micromanipulation ; Mouse embryo ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new micromanipulation technique permitted the scrambling of the zygote cytoplasm. Such interference had no effect on preimplantation development, and when zygotes with scrambled cytoplasm were transfered to the pseudopregnant females, normal and fertile mice were born. This demonstrates that no morphogenetic factors are prelocalized in the egg cytoplasm. Cleavage characteristics of mouse embryos provide the evidence that zygote cytoplasm does not define any determinate type of cleavage. We conclude that the mechanism of ooplasmic segregation is not used in the mouse (and presumably mammalian) development. It is suggested that the turning point in the evolution of mammalian embryogenesis was the transition to the intrauterine development, that started the process leading among other changes, to the loss of the ooplasmic morphogenetic determinants.
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    URL: http://dx.doi.org/10.1007/BF00636335
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    Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff (1994)
    Springer
    Bulletin of volcanology 56 (1994), S. 377-385 
    Details
    ISSN: 1432-0819
    Keywords: Zoned magma body ; Chemical variation ash-flow sheets ; Tephra sequence ; Differentiation time constraints ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 — one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55–66% SiO2) and a high silica (〉66% SiO2) trend. Ninety per cent of the Rainier Mesa sheet occurs in the high silica trend. Immediately beneath the Rainier Mesa sheet is a thick tephra sequence. The chemical variation of this sequence is nearly equivalent to the high silica portion of the Rainier Mesa ash-flow sheet (about 66–78% SiO2). Throughout the tephra sequence numerous small ash-flow layers occur, and each ash-flow layer is chemically zoned from more evolved at the base to less evolved at the top. This is consistent with having been erupted from a zoned magma body. The lowest silica tephra units are at the base of the sequence and the highest silica units are at the top — that is, the large-scale chemical trend of the entire sequence is opposite to that of the individual ash-flow layers. These ash-flow layers are of very small volume. The tephra sequence provides a unique record of the incremental development of the zoned, high silica portion of the Rainier Mesa magma body.
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    Phenotypic plasticity and nutrition in a phytophagous insect: consequences of colonizing a new host (1994)
    Springer
    Oecologia 100 (1994), S. 379-385 
    Details
    ISSN: 1432-1939
    Keywords: Tephritidae ; Phenotypic plasticity ; Phytophagous insects ; Evolution ; Selection regime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The European rose-hip fruit fly Rhagoletis alternata (Diptera, Tephritidae) infests hips of Rosa species. This fly includes R. rugosa, an Asian species now cultivated all over Europe, in its host range. Differences in size and biomass of hips between the ancestral host R. canina and the new host translate into better growth, shorter larval development of larvae within hips of R. rugosa and larger body size and fertility of flies which developing in the new host. In turn this causes different interactions with other organisms of the food-web centred on the host plant. The importance of nutrition and phenotypic plasticity is twofold: they generate a considerable part of life-history diversity within a species and reinforce differences in the ecological context of the ancestral and new host.
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    URL: http://dx.doi.org/10.1007/BF00317858
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    Measuring the effect of an abiotic stress on competition (1994)
    Springer
    Oecologia 100 (1994), S. 221-228 
    Details
    ISSN: 1432-1939
    Keywords: Triticum aestivum ; Competition ; Abiotic stress ; Multiplicative interactions ; Nickel toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using recently developed solution culture techniques, the effect of a non-resource abiotic stress, nickel toxicity, was tested on intraspecific nutrient competition among wheat. The choice of an appropriate statistical model was of paramount importance in interpreting these effects. We argue that a multiplicative model is more appropriate for experiments on interactions of competition and abiotic stress. By such an analysis, nickel had no relative effect on the ability of competition to reduce plant size in two experiments, and caused a small reduction in competition in another. These results are contrary to other reports of the effect of a non-resource abiotic stress on competition and appear to be due to an increased demand for nutrients in the presence of toxic levels of nickel. The effects of an abiotic stress on competition may thus be specitic to the stress and not generalized across all abiotic stresses.
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    Pollen mitosis in the slipper orchid Cypripedium fasciculatum (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 87-94 
    Details
    ISSN: 1432-2145
    Keywords: Evolution ; Microtubules ; Polarity Pollen ; Mitosis ; Orchids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollen mitosis in the slipper orchid Cypripedium fasciculatum was studied using correlated methods of immunofluorescence and transmission electron microscopy. Unlike the more highly evolved orchids, the cypripedioid orchids shed pollen as monosulcate monads. Prior to pollen mitosis, the microspore nucleus migrates to a proximal position opposite the aperture, as is typical of monocotyledons. There is no distinct generative pole microtubule system (GPMS) like that recently reported in development of pollen polarity in the vandoid moth orchid Phalaenopsis. Instead, microtubules in early prophase are concentrated around the nucleus and extend into the cytoplasm toward the future generative pole. Once the nucleus has migrated to the continuous surface opposite the aperture, microtubules surround the nucleus evenly and show no tendency to be more concentrated in the generative domain. The mitotic spindle, which develops from the perinuclear microtubules, is asymmetrically placed in the microspore and is cone-shaped. The generative pole is broad and closely appressed to the continuous spore surface, while the vegetative pole is pointed and located in the interior of the microspore. As the chromosomes move poleward, microtubules proliferate in the interzone and a phragmoplast develops. The phragmoplast expands in a hemispherical path beyond the interzone following an array of microtubules that radiates from the generative nucleus. Data from this study indicate that evolution of pollen in orchids includes a shift in location of the generative cell from proximal to distal and the evolution of a GPMS, in addition in the well-known trend toward increased pollen aggregation and loss of exine.
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    Gene transfer to inflorescence and flower meristems using ballistic micro-targeting (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 135-143 
    Details
    ISSN: 1432-2145
    Keywords: Flower ; Meristem ; Gene transfer Particle bombardment ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Direct gene transfer to floral meristems could contribute to cell-fate mapping, to the study of flower-specific genes and promoters, and to the production of transgenic gametes via the transformation of sporogenic tissues. Despite the wide potential of its applications, direct gene transfer to floral meristems has not been achieved so far because of the lack of suitable technology. We show in this paper that ballistic micro-targeting is the technique of choice for this purpose, and in this way, we were able to transfer genes efficiently into excised wheat immature spikes. Particle size was adjusted for optimal penetration into the L1 and L2 cell layers of the spikes with limited cell damage. Spikes at different developmental stages were shot either with a plasmid containing two genes involved in anthocyanin biosynthesis or with a plasmid bearing the uidA (β-glucuronidase) gene. The transient expression of these marker genes was observed in the different developmental stages tested and in cells of both the L1 and the L2 layers. The transient expression of the uidA gene was significantly increased when the sucrose concentration in the culture medium was increased from 0.06 to 0.52 M. At the highest concentration, 100% of the targeted spikes expressed the uidA gene, with an average of 69 blue cells per spike. Twelve days after microtargeting, multicellular sectors showing transgene expression and containing up to 17 cells were found in 85% of the shot immature inflorescences. This indicated that targeted cells survived particle bombardment. Sectors were found in primordia of both vegetative and reproductive organs.
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    Mitochondrial DNA variability detected in a single wheat regenerant involves a rare recombination event across a short repeat (1994)
    Springer
    Current genetics 25 (1994), S. 456-464 
    Details
    ISSN: 1432-0983
    Keywords: Reciprocal recombination ; Mitochondrial genome ; Chondriome variability ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mitochondrial genome of the selfed progeny of a plant regenerated from long-term somatic tissue culture displays specific structural rearrangements characterized by the appearance of novel restriction fragments. A mitochondrial DNA library was constructed from this selfed progeny in the SalI site of cosmid pHC79 and the novel fragments were subsequently studied. They were shown to arise from reciprocal recombination events involving DNA sequences present in the parental plant. The regions of recombination were sequenced and the nucleotide sequences were aligned with those of the presumptive parental fragments. We characterized an imperfect short repeated DNA sequence, 242 bp long, within which a 7-bb DNA repeat could act as a region of recombination. The use of PCR technology allowed us to show that these fragments were present in both parental plants and tissue cultures as low-abundance sequence arrangements.
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    Effects of 15N-labelled ammonium nitrate and urea on soil nitrogen during growth of wheat (Triticum aestivum L.) under field conditions (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 232-236 
    Details
    ISSN: 1432-0789
    Keywords: 15N-labelled fertilizer ; Added N interaction ; Fertilizer N uptake ; Soil N uptake ; Wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the effects of 15N-labelled ammonium nitrate and urea on the yield and uptake of labelled and unlabelled N by wheat (Triticum aestivum L., cv. Mexi-Pak-65) in a field experiment. The dry matter and N yields were significantly increased with fertilizer N application compared to those from unfertilized soil. The wheat crop used 33.6–51.5 and 30.5–40.9% of the N from ammonium nitrate and urea, respectively. Splitting the fertilizer N application had a significant effect on the uptake of fertilizer N by the wheat. The fertilizer N uptake showed that ammonium nitrate was a more available source of N for wheat than urea. The effective use of fertilizer N (ratio of fertilizer N in grain to fertilizer N in whole plant) was statistically similar for the two N fertilizers. The application of fertilizer N increased the uptake of unlabelled soil N by wheat, a result attributed to a positive added N interaction, which varied according to the fertilizer N split; six split applications gave the highest added N interaction compared to a single application or two split applications for both fertilizers. Ammonium nitrate gave 90.5, 33.5, and 48.5% more added N interaction than urea with one, two, and six split N applications. A values were not significantly correlated with the added N interaction (r=0.557). The observed added N interaction may have been the result of pool substitution, whereby added labelled fertilizer N replaced unlabelled soil N.
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    Sequence divergence of the murB and rrfB genes from Escherichia coli and Salmonella typhimurium (1994)
    Springer
    Archives of microbiology 161 (1994), S. 501-507 
    Details
    ISSN: 1432-072X
    Keywords: Escherichia coli ; Salmonella typhimurium ; murB ; rrfB ; Repetitive extragenic palindrome ; Evolution ; Mutation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The murB gene of Salmonella typhimurium was cloned and found to be 75% and 82% identical to the DNA and protein sequences, respectively, of the same gene in Escherichia coli. These identities are among the lowest recorded between the two bacteria. Nevertheless, wild-type S. typhimurium murB complemented the known temperature-sensitive E. coli mutant, and wild-type E. coli murB complemented three temperature-sensitive mutants of S. typhimurium. The 5S rRNA gene, rrfB, and the region between murB and rrfB were also cloned and sequenced. The rrfB gene of S. typhimurium differs from rrfB of E. coli in only 2 of 120 nt, but the region between murB and rrfB has diverged greatly and includes a sequence that elosely resembles a repetitive extragenic palindrome of the type normally associated with E. coli. Previous comparisons of gene divergence have suggested that the chromosomal mutation rate is lower in the vicinity of the origin of replication. However, the S. typhimurium murB gene, located 6 map minutes from the origin of replication, is highly substituted at synonymous sites and the sequence between murB and rrfB is significantly modified as well. Thus, murB is an exception to the general observation that genes near the origin of replication show less divergence than do genes elsewhere in the bacterial chromosome.
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    Primary structure of hemoglobin from cobraNaja naja naja (1994)
    Springer
    The protein journal 13 (1994), S. 669-679 
    Details
    ISSN: 1573-4943
    Keywords: Evolution ; hemoglobin ; primary structure ; snake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cobra snakeNaja naja naja hemoglobin shows four bands on Triton electrophoresis. We present the primary structure of oneα and oneβ chain. The separation of polypeptide chains was achieved by ion exchange chromatography on carboxymethyl cellulose column. The amino acid sequence was established by automatic Edman degradation of the native chains and tryptic and hydrolytic peptides in a gas-phase sequencer. The structural data are compared with those of human and other reptile hemoglobins and reveal not only large variations from human but within reptiles. The amino acid exchanges involve several subunit contacts and heme binding sites. This is the first study on the hemoglobin of a land snake. There are only two amino acid sequences of sea snake hemoglobin (Microcephalophis gracilis gracilis andLiophis miliaris) reported in the literature.
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    Molecular cloning of the Arabidopsis thaliana sedoheptulose-1,7-biphosphatase gene and expression studies in wheat and Arabidopsis thaliana (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1191-1200 
    Details
    ISSN: 1573-5028
    Keywords: Calvin cycle genes ; gene expression ; SBPase ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report here the isolation and nucleotide sequence of genomic clones encoding the chloroplast enzyme sedoheptulose-1,7-bisphosphatase (SBPase) from Arabidopsis thaliana. The coding region of this gene contains eight exons (72–76 bp) and seven introns (75–91 bp) and encodes a polypeptide of 393 amino acids. Unusually, the 5′ non-coding region contains two additional AUG codons upstream of the translation initiation codon. A comparison of the deduced Arabidopsis and wheat SBPase polypeptide sequences reveals 78.6%, identity. Expression studies showed that the level of SBPase mRNA in Arabidopsis and wheat is regulated in a light-dependent manner and is also influenced by the developmental stage of the leaf. Although the Arabidopsis SBPase gene is present in a single copy, two hybridizing transcripts were detected in some tissues, suggesting the presence of alternate transcription start sites in the upstream region.
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    Firm selection and industry evolution: the post-entry performance of new firms (1994)
    Springer
    Journal of evolutionary economics 4 (1994), S. 243-260 
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    ISSN: 1432-1386
    Keywords: Innovation ; Evolution ; Survival and growth ; O ; O3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract A dynamic framework based on the process of firm selection and industry evolution is used to analyse the post-entry performance of new firms. In particular, it is hypothesized that, based on the stylized fact that virtually all new firms start at a very small scale of output, firm growth and survival are shaped by the need to attain an efficient level of output. The post-entry performance of more than 11,000 U.S. manufacturing firms established in 1976 is tracked throughout the subsequent tenyear period. Firm growth is found to be negatively influenced by firm size but positively related to the extent of scale economies, capital intensity, innovative activity, and market growth. By contrast, the likelihood of survival is identified as being positively influenced by firm size, market growth, and capital intensity, but negatively affected by the degree of scale economies in the industry. When viewed through the dynamic framework of firm selection and industry evolution, the empirical results shed considerable light on several paradoxes in the industrial organization literature, such as the continued persistence over time of an asymmetrical firm-size distribution consisting predominantely of suboptimal scale firms, and the failure of capital intensity and scale economies to substantially deter the entry and start-up of new firms.
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    Transfer of Ph I genes promoting homoeologous pairing from Triticum speltoides to common wheat (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 97-101 
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    ISSN: 1432-2242
    Keywords: Triticum aestivum ; T. speltoides ; Meiotic chromosome pairing ; Alien transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diploid-like chromosome pairing in polyploid wheat is controlled by several Ph (pairing homoeologous) genes with major and minor effects. Homoeologous pairing occurs in either the absence of these genes or their inhibition by genes from other species (Ph I genes). We transferred Ph I genes from Triticum speltoides (syn Aegilops speltoides) to T. aestivum, and on the basis of further analysis it appears that two duplicate and independent Ph I genes were transferred. Since Ph I genes are epistatic to the Ph genes of wheat, homoeologous pairing between the wheat and alien chromosomes occurs in the F1 hybrids. Using the Ph I gene stock, we could demonstrate homoeologous pairing between the wheat and Haynaldia villosa chromosomes. Since homoeologous pairing occurs in F1 hybrids and no cytogenetic manipulation is needed, the Ph I gene stock may be a versatile tool for effecting rapid and efficient alien genetic transfers to wheat.
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    Wheat chromosome 2D carries genes controlling the activity of two DNA-degrading enzymes (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 30-32 
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    ISSN: 1432-2242
    Keywords: Triticum aestivum ; DNase ; Nuclease ; Cytogenetics ; Gene mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract DNA-degrading enzymes of 24.0 kDa and 27.0 kDa were observed to have different activities in two common wheat (Triticum aestivum L.) cultivars, ‘Wichita’ and ‘Cheyenne’. A substrate-based SDS-PAGE assay revealed that these two enzymes were much more active in ‘Wichita’ than in ‘Cheyenne’. Genes controlling the activities of these two enzymes were localized on chromosome 2D by testing DNA-degrading activities in reciprocal chromosome substitution lines between ‘Wichita’ and ‘Cheyenne’. While the allele on ‘Wichita’ chromosome 2D stimulated the activities of the 24.0- and 27.0-kDa enzymes in Cheyenne, the allele on ‘Cheyenne’ chromosome 2D did not reduce the activities of the 24-kDa and 27-kDa enzymes in ‘Wichita’. Whether these genes code for the DNA-degrading enzymes themselves or for factors that regulate the enzyme activities remains unknown.
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    PCR analysis of genes encoding allelic variants of high-molecular-weight glutenin subunits at the Glu-D1 locus (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 175-180 
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    ISSN: 1432-2242
    Keywords: HMW-glutenin genes ; Electrophoresis ; Polymerase chain reaction ; Molecular weight determination ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genes encoding high-molecular-weight (HMW) glutenin subunits, present in bread-wheat lines and cultivars, were studied by RFLP (restriction fragment length polymorphism) and PCR (polymerase chain reaction) analyses. In particular, allelic subunits of the x-or y-type, encoded at the Glu-D1 locus present on the long arm of chromosome 1D, were investigated. The variation in size, observed in different allelic subunits, is mainly due to variation in the length of the central repetitive domain, typical of these proteins. Deletions or duplications, probably caused by unequal crossingover, have given rise to the size heterogeneity currently observed. The possibility of using the PCR technique for a detailed analysis of HMW glutenin genes in order to obtain a more accurate estimation of the molecular weight of their encoded subunits, and the detection of unexpressed genes, is also described.
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    Chromosome assortment in Saccharum (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 959-963 
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    ISSN: 1432-2242
    Keywords: Sugarcane ; Polyploidy ; Genetics ; Evolution ; Breeding ; DNA markers ; Arbitrarily primed PCR ; RAPD markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum ‘SES 208’ and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum ‘LA Purple’ and Saccharum robustum ‘ Mol 5829’. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.
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    Characterization of a family of tandemly repeated DNA sequences in Triticeae (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 217-225 
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    ISSN: 1432-2242
    Keywords: Evolution ; Tandemly repeated DNA sequences ; Phylogenetic relationships ; RFLP ; Poaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The recombinant plasmid dpTa1 has an insert of relic wheat DNA that represents a family of tandemly organized DNA sequences with a monomeric length of approximately 340 bp. This insert was used to investigate the structural organization of this element in the genomes of 58 species within the tribe Triticeae and in 7 species representing other tribes of the Poaceae. The main characteristic of the genomic organization of dpTa1 is a classical ladder-type pattern which is typical for tandemly organized sequences. The dpTa1 sequence is present in all of the genomes of the Triticeae species examined and in 1 species from a closely related tribe (Bromus inermis, Bromeae). DNA from Hordelymus europaeus (Triticeae) did not hybridize under the standard conditions used in this study. Prolonged exposure was necessary to obtain a weak signal. Our data suggest that the dpTa1 family is quite old in evolutionary terms, probably more ancient than the tribe Triticeae. The dpTa1 sequence is more abundant in the D-genome of wheat than in other genomes in Triticeae. DNA from several species also have bands in addition to the tandem repeats. The dpTa1 sequence contains short direct and inverted subrepeats and is homologous to a tandemly repeated DNA sequence from Hordeum chilense.
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    A study of genetic variation and evolution of Phyllostachys (Bambusoideae: Poaceae) using nuclear restriction fragment length polymorphisms (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 265-270 
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    ISSN: 1432-2242
    Keywords: Bamboo ; Phyllostachys ; RFLP ; Variation ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic and taxonomic difficulties are common within the woody bamboos, due to their unique life cycle, which severely limits the availability of floral characters. To addresss some of these problems, 20 species of woody bamboos in the genus Phyllostachys were analyzed using nuclear restriction fragment length polymorphisms (RFLPs). The RFLP data were used to generate genetic distances between all pairs of taxa and to examine the degree of genetic variation within and among bamboo species. The genetic distances were also used to create dendrograms of accessions and species. These trees supported the current division of the genus into two sections and provided some information on the thorny taxonomic problems in this group. We show that RFLPs can be used for species identification and the delineation of species limits.
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    A monoclonal antibody chromosome marker analysis used to locate a loose smut resistance gene in wheat chromosome 6A (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 787-793 
    Details
    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Ustilago tritici ; Alien substitution ; Molecular marker ; Gene location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Many genes have been located in wheat chromosomes, yet little is known about the location of genes for resistance to Ustilago tritici, which causes loose smut. Crosses were made between the loose smut susceptible alien substitution lines Cadet 6Ag(6A) and Rescue 6Ag(6A) (lines in which Agropyron chromosome 6 is substituted by wheat chromosome 6A) and four cultivars resistant to U. tritici race T19: ‘Cadet’, ‘Kota’, ‘Thatcher’ and ‘TD18’. The segregating progeny were tested for reaction to race T19 and for the level of binding with a monoclonal antibody specific to a chromosome 6A-coded seed protein. The antibody, which does not bind to seed protein extracts in the absence of the 6A chromosome, was used as a chromosome marker. An association was established between resistance to race T19 and the presence of chromosome 6A for each of the cultivars tested, indicating that resistance to race T19 resides in chromosome 6A. Ustilago tritici race T19 resistance in ‘Cadet’ appears to be located in the short arm of chromosome 6A, based on the evaluation of the Cadet 6A long ditelosomic stock, which was susceptible, and the Cadet 6A-short: 6-Agropyron- short alien translocation stock, which was resistant.
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    Molecular analysis of plants regenerated from embryogenic cultures of wheat (Triticum aestivum L.) (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 821-828 
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    ISSN: 1432-2242
    Keywords: RFLP ; Tissue culture ; Triticum aestivum ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Total DNAs of plants regenerated from immature embryo-derived 2-month-old embryogenic calli of wheat (cultivars Florida 302, Chris, Pavon, RH770019) were probed with six maize mitochondrial genes (atpA, atp6, apt9, coxI, coxII, rrn18-rrn5), three hypervariable wheat mitochondrial clones (K′, K3, X2), five random pearl millet mitochondrial clones (4A9, 4D1, 4D12, 4E1, 4E11) and the often-used wheat Nor locus probe (pTA71), in order to assess the molecular changes induced in vitro. In addition, protoplast-derived plants, and 24-month-old embryogenic and non-embryogenic calli and cell suspension cultures of Florida 302 were also analyzed. No variation was revealed by the wheat or millet mitochondrial clones. Qualitative variation was detected in the nonembryogenic suspension culture by three maize mitochondrial genes (coxI, rrn18-rrn5, atp6). A callus-specific 3.8-kb Hind III fragment was detected in all four cultivars after hybridization with the coxI gene. The organization of the Nor locus of the plants regenerated from Florida 302 and Chris was stable when compared to their respective control plants and calli. The Nor locus in regenerants of Pavon and RH, on the other hand, was found to be variable. However, Nor locus variability was not observed in 14 individual seed-derived control plants from either Pavon or RH sources. In Pavon, a 3.6-kb Taq I or a 5.6-kb Bam HI+ Eco RI fragment was lost after regeneration. In one of the RH regenerants, which lost a fragment, an additional fragment was observed.
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    Identification and localization of molecular markers linked to the Lr9 leaf rust resistance gene of wheat (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 110-115 
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    ISSN: 1432-2242
    Keywords: Leaf rust ; RAPD ; RFLP ; Triticum aestivum ; Triticum spelta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Near-isogenic lines (NILs) for the leaf rust resistance gene Lr9 were screened for polymorphisms at the molecular level. RAPD (random amplified polymorphic DNA) primers as well as RFLP (restriction fragment length polymorphism) markers were used. Out of 395 RAPD primers tested, three showed polymorphisms between NILs, i.e., an additional band was found in resistant lines. One of these polymorphic bands was cloned and sequenced. Specific primers were synthesized, and after amplification only resistant lines showed an amplified product. Thus, these primers define a sequence-tagged site that is specific for the translocated fragment carrying the Lr9 gene. A cross between a resistant NIL and the spelt (Triticum spelta) variety ‘Oberkulmer’ was made, and F2 plants were analyzed for genetic linkage. All three polymorphisms detected by the PCR (polymerase chain reaction) and one RFLP marker (cMWG684) showed complete linkage to the Lr9 gene in 156 and 133 plants analyzed, respectively. A second RFLP marker (PSR546) was closely linked (8±2.4 cM) to the Lr9 gene and the other four DNA markers. As this marker maps to the distal part of the long arm of chromosome 6B of wheat, Lr9 and the other DNA markers also map to the distal region of 6BL. All three PCR markers detected the Lr9 gene in independently derived breeding lines and varieties, thus proving their general applicability in wheat breeding programs.
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    RFLP markers associated with Sr22 and recombination between chromosome 7A of bread wheat and the diploid species Triticum boeoticum (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 1039-1045 
    Details
    ISSN: 1432-2242
    Keywords: RFLP ; Sr22 ; Triticum aestivum ; T. boeoticum ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of the bread wheat variety Schomburgk, and related lines in its pedigree, identified RFLP markers associated with the segment of chromosome 7A carrying the Sr22 gene derived from the diploid species T. boeoticum. The distribution of the RFLP markers indicated that at least 50% of 7AS and 80% of 7AL in Schomburgk is of T. boeoticum origin. Evaluation of five sets of nearisogenic lines, backcross lines in 20 different genetic backgrounds and an F2 population segregating for Sr22 demonstrated a very low level of recombination between the 7A chromosomes of T. boeoticum and T. aestivum. Several recombinants carrying Sr22 but with a much reduced segment of T. boeoticum were identified and these may prove useful in the breeding of further varieties with Sr22.
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    Identification of wheat-Agropyron cristatum monosomic addition lines by RFLP analysis using a set of assigned wheat DNA probes (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 70-75 
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    ISSN: 1432-2242
    Keywords: Triticum aestivum ; Agropyron cristatum ; Alien addition ; RFLP ; Non-radioactive labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A non-radioactive digoxigenin-labelled DNA method was used successfully to identify RFLP markers in 54 Triticum aestivum cv ‘Chinese Spring’ — Agropyron cristatum (2n=28, genome PPPP) P-genome monosomic addition lines. Southern analysis using a set of 14 DNA probes identifying each homoeologous chromosome arm, combined with two restriction enzymes HindIII and EcoRI, indicated that six A. cristatum chromosomes (1P, 2P, 3P, 4P, 5P and 6P) and five A. cristatum chromosome arms (2PS, 2PL, 5PL, 6PS and 6PL) have been individually added to the wheat genome. The added chromosomes of three lines were Agropyron translocated chromosomes. It was also found that two addition plants possessed an Agropyron-wheat translocation. These results showed that RFLP analysis using the set of assigned wheat probes was a powerful tool in detecting and establishing homoeology of alien A. cristatum chromosomes, or arms, added to wheat, as well as in screening the alien addition material. The creation of the monosomic addition lines should be useful for the transfer of disease-resistance genes from A. cristatum to wheat.
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    Identification of RFLP markers linked to the cereal cyst nematode resistance gene (Cre) in wheat (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 927-930 
    Details
    ISSN: 1432-2242
    Keywords: Restriction fragment length polymorphism ; CCN ; Genetic mapping ; Triticum aestivum ; Heterodera avenae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cereal cyst nematode (CCN) (Heterodera avenae Woll.) is an economically damaging pest of wheat in many of the worlds cereal growing areas. The development of CCN-resistant cultivars may be accelerated by the use of molecular markers. The Cre gene of the wheat line “AUS 10894” confers resistance to CCN. Using a pair of near-isogenic lines (NILs) that should differ only in a small chromosome segment containing the Cre locus, we screened 58 group-2 probes and found two (Tag605 and CDO588) that detect polymorphism between the NILs. Nulli-tetrasomic and ditelosomic lines confirmed that the restriction fragment length polymorphism (RFLP) markers identified were derived from the long arm of wheat chromosome 2. Crosses between “AUS 10894” and “Spear” and the NIL “AP” and its recurrent parent “Prins” were used to produce F2 populations that gave the expected 3∶1 segregation ratio for the resistance gene. Linkage analysis identified two RFLP markers flanking the resistance gene. Xglk605 and Xcdo588 mapped 7.3 cM (LOD=6.0) and 8.4 cM (LOD=6.7), respectively, from the Cre locus.
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    Length variation in the internal transcribed spacers of ribosomal DNA in Picea abies and related species (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 969-974 
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    ISSN: 1432-2242
    Keywords: Evolution ; rDNA ; Internal transcribed spacers ; Picea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure and variation of nuclear ribosomal DNA (rDNA) units of Picea abies, (L.) Karst. was studied by restriction mapping and Southern hybridization. Conspicuous length variation was found in the internal transcribed spacer (ITS) region of P. abies, although the length of this region is highly conserved both within and among most of the plant species. Two types of ITS variants (A and B), displaying a size difference of 0.5 kb in the ITS2 region, were present within individuals of P. abies from Sweden, Central Europe and Siberia. A preliminary survey of 14 additional Eurasian and North American species of Picea suggested that length variation in the ITS region is widespread in this genus. Alltogether three length variants (A, B and C) were identified. Within individuals of eight Picea species, two length variants were present within the genome (combinations of A and B variants in P. glehnii, P. maximowiczii, P. omorika, P. polita and P. sitchensis and variants B and C in P. jezoensis, P. likiangensis and P. spinulosa). Within individuals from five species, however only one rDNA variant was present in their genome (variant A in P. aurantiaca, P. engelmannii, P. glauca, P. koraiensis and P. koyamai; variant B in P. bicolor). The ITS length variation will be useful as a molecular marker in evolutionary studies of the Picea species complex, whose phylogeny is controversial. The presence of intraindividual variation in, and shared polymorphism of the, ITS length variants raises questions about the occurrence of interspecific hybridization during the evolutionary history of Picea.
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    Phylogenetic analysis of chloroplast restriction enzyme site mutations in the Saccharinae Griseb. subtribe of the Andropogoneae Dumort. tribe (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 843-853 
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    ISSN: 1432-2242
    Keywords: Sugarcane ; Saccharm ; Evolution ; Cytoplasmic inheritance ; Restriction mapping ; Cladistics ; Parsimony ; Dollo parsimony ; Wagner parsiomony ; Maximum likelihood ; Saccharum complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chloroplast (cp) DNA from 32 genotypes representing eight genera and 19 species from the Andropogoneae tribe was analyzed using 15 restriction enzymes and Southern hybridization with 12 cpDNA probes that span the complete rice chloroplast genome. Six of the genera, Saccharum, Miscanthus, Erianthus, Narenga, Eccoilopus, and Sclerostachya, are part of the Saccharinae subtribe, whereas the other two, Zea and Sorghum, were used as outgroups. Narenga, Miscanthus, Erianthus, and Sclerostachya are presumed to have been involved in the evolution of Saccharum officinarum (“noble” or high sucrose sugarcane) via S. spontaneum and S. robustum. Southern hybridization with the rice cpDNA probes surveyed approximately 3% of the S. officinarum ‘Black Cheribon’ genome and yielded 62 restriction site mutations (18 informative) that were analyzed using cladistic parsimony and maximum likelihood. These site mutations placed the 32 genotypes into nine different chloroplast groups; seven from within the Saccharinae subtribe and the two outgroups (maize and Sorghum). Phylogenetic inferrence under various assumptions showed that the maternal lineages of Narenga, Miscanthus, Sclerostachya, and Saccharum formed a monophyletic group. This group displayed little variation. On the other hand, 5 of 6 Erianthus species and Eccoilopus longisetosus formed a separate group. The ‘Old World’ Erianthus/Eccoilopus chloroplast was very different from that of the rest of the ‘Saccharum complex’ members and was slightly more related to that of Sorghum bicolor. Placement of these Erianthus/Eccoilopus genotypes was, therefore, in conflict with analyses based on morphology. Surprisingly, Erianthus trinii, a New World species, had the same restriction sites as did one Miscanthus sinensis. One Miscanthus sp. from New Guinea that has a very high chromosome number (2n=192) had the same restriction sites as the majority of the Saccharum genus, suggesting that introgression between these genera occurs in the wild. The Saccharum genus was separated into two clades by single site mutation: one containing S. spontaneum, and the other containing all of the remaining Saccharum species and all 8 commerical hybrids (from various regions of the world). A physical map of the chloroplast of Saccharum officinarum ‘Black Cheribon’ was constructed using 5 restriction enzymes.
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    The generation of Mutator transposable element subfamilies in maize (1994)
    Springer
    Theoretical and applied genetics 87 (1994), S. 657-667 
    Details
    ISSN: 1432-2242
    Keywords: Transposable elements ; Mutation ; Evolution ; DNA repair ; Gene conversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The mobile DNAs of the Mutator system of maize (Zea mays) are exceptional both in structure and diversity. So far, six subfamilies of Mu elements have been discovered; all Mu elements share highly conserved terminal inverted repeats (TIRs), but each sub-family is defined by internal sequences that are apparently unrelated to the internal sequences of any other Mu subfamily. The Mu1/Mu2 subfamily of elements was created by the acquisition of a portion of a standard maize gene (termed MRS-A) within two Mu TIRs. Beside the unusually long (185–359 bp) and diverse TIRs found on all of these elements, other direct and inverted repeats are often found either within the central portion of a Mu element or within a TIR. Our computer analyses have shown that sequence duplications (mostly short direct repeats interrupted by a few base pairs) are common in non-autonomous members of the Mutator, Ac/Ds, and Spm(En) systems. These duplications are often tightly associated with the element-internal end of the TIRs. Comparisons of Mu element sequences have indicated that they share more terminal components than previously reported; all subfamilies have at least the most terminal 215 bp, at one end or the other, of the 359-bp Mu5 TIR. These data suggest that many Mu element subfamilies were generated from a parental element that had termini like those of Mu5. With the Mu5 TIRs as a standard, it was possible to determine that elements like Mu4 could have had their unusual TIRs created through a three-step process involving (1) addition of sequences to interrupt one TIR, (2) formation of a stem-loop structure by one strand of the element, and (3) a subsequent DNA repair/gene conversion event that duplicated the insertion(s) within the other TIR. A similar repair/conversion extending from a TIR stem into loop DNA could explain the additional inverted repeat sequences added to the internal ends of the Mu4 and Mu7 TIRs. This same basic mechanism was found to be capable of generating new Mu element subfamilies. After endonucleolytic attack of the loop within the stem-loop structure, repair/conversion of the gap could occur as an intermolecular event to generate novel internal sequences and, therefore, a new Mu element subfamily. Evidence supporting and expanding this model of new Mu element subfamily creation was identified in the sequence of MRS-A.
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    Waxy protein deficiency and chromosomal location of coding genes in common wheat (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 179-184 
    Details
    ISSN: 1432-2242
    Keywords: Waxy (Wx) protein ; Triticum aestivum ; Null allele ; Geographical distribution ; Chromosomal location
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Deficiency of the wheat waxy (Wx) proteins (Wx-A1, Wx-B1 and Wx-D1) was studied in 1,960 cultivars derived from several countries. Gel electrophoretic analyses revealed that the null allele for the Wx-A1 protein occurred frequently in Korean, Japanese and Turkish wheats but was relatively rare in cultivars from other countries and regions. About 48% of the wheats deficient for the Wx-B1 protein were from Australia and India. One Chinese cultivar lacked the WxD1 protein. While 9 Japanese cultivars were deficient in both the Wx-A1 and Wx-B1 proteins, no cultivars lacked both the Wx-A1 and Wx-D1 proteins, both the Wx-B1 and Wx-D1 proteins or all three Wx proteins. Two-dimensional gel electrophoresis revealed polymorphisms of the three Wx proteins that varied according to isoelectric points or molecular weight. The Wx-A1 gene coding the Wx-A1 protein and the Wx-B1 gene coding the Wx-B1 protein were localized in the distal regions of chromosome arms 7AS and 4AL, respectively, by deletion mapping using the deletion lines developed in the common wheat cultivar ‘Chinese Spring’.
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    URL: http://dx.doi.org/10.1007/BF00225138
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    Genetic control of amylose content in wheat endosperm starch and differential effects of three Wx genes (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 276-280 
    Details
    ISSN: 1432-2242
    Keywords: Amylose content ; Monosomic ; Substitution line ; Triticum aestivum ; Wx protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The endosperm starch of the wheat grain is composed of amylose and amylopectin. Genetic manipulation of the ratio of amylose to amylopectin or the amylose content could bring about improved texture and quality of wheat flour. The chromosomal locations of genes affecting amylose content were investigated using a monosomic series of Chinese Spring (CS) and a set of Cheyenne (CNN) chromosome substitution lines in the CS genetic background. Trials over three seasons revealed that a decrease in amylose content occurred in monosomic 4A and an increase in monosomic 7B. Allelic variation between CS and CNN was suggested for the genes on chromosomes 4A and 7B. To examine the effects of three Waxy (Wx) genes which encode a granule-bound starch synthase (Wx protein), the Wx proteins from CS monosomics of interest were analyzed using SDS-PAGE. The amount of the Wx protein coded by the Wx-B1 gene on chromosome arm 4AL was reduced in monosomic 4A, and thus accounted for its decreased amylose content. The amounts of two other Wx proteins coded by the Wx-A1 and Wx-D1 genes on chromosome arms 7AS and 7DS, respectively, showed low levels of protein in the monosomics but no effect on amylose content. The effect of chromosome 7B on the level of amylose suggested the presence of a regulator gene which suppresses the activities of the Wx genes.
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    URL: http://dx.doi.org/10.1007/BF00225154
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    Polymorphisms in the α-amy1 gene of wild and cultivated barley revealed by the polymerase chain reaction (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 509-513 
    Details
    ISSN: 1432-2242
    Keywords: α-amylase ; Barley ; DNA polymorphism ; Evolution ; Polymerase chain reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract α-Amylases are the key enzymes involved in the hydrolysis of starch in plants. The polymerase chain reaction (PCR) was used to detect polymorphisms in the length of amplified sequences between the annealing sites of two primers derived from published α-amy1 gene sequences in barley. These two primers (Bsw1 and Bsw7), flanking the promoter region and the first exon, amplified two PCR fragments in barley. One of the amplified products, with the expected length of 820 bp, appeared together with another shorter PCR band of around 750 bp. This 750-bp fragment seems to be derived from an α-amylase gene not reported previously. Both of the PCR products could be amplified from the two-rowed barley varieties tested, including cv Himalaya from which the sequence information was obtained. Five of the six-rowed barley varieties also have the two PCR fragments whereas another two have only the long fragment. These two fragments seem to be unique to barley, neither of them could be amplified from other cereals; for example, wheat, rye or sorghum. These two α-amylase fragments were mapped to the long arm of 6H, the location of the α-amy1 genes, using wheat-barley addition lines. Amplification of genomic DNA from wild barley accessions with primers Bsw1 and Bsw7 indicated that both of the fragments could be present, or the long and short fragments could be present alone. The results also demonstrated that the genes specifying these two fragments could be independent from each other in barley. The conserved banding pattern of these two fragments in the two-rowed barley varieties implies that artificial selection from these genes may have played an important role in the evolution of cultivated barley from wild barley.
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    URL: http://dx.doi.org/10.1007/BF00225388
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    A comparative study of leucokinin-immunoreactive neurons in insects (1994)
    Springer
    Cell & tissue research 276 (1994), S. 69-83 
    Details
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Vasopressin ; Diuresis ; Neurohemal organ ; Evolution ; Nauphoeta cinerea ; Aedes aegypti ; Acheta domesticus ; Schistocerca americana (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Antisera were raised against leucokinin IV, a member of the leucokinin peptide family. Immunohistochemical localization of leucokinin immunoreactivity in the brain of the cockroach Nauphoeta cinerea revealed neurosecretory cells in the pars intercerebralis and pars lateralis, several bilateral pairs of interneurons in the protocerebrum, and a group of interneurons in the optic lobe. Several immunoreactive interneurons were found in the thoracic ganglia, while the abdominal ganglia contained prominent immunoreactive neurosecretory cells, which projected to the lateral cardiac nerve. The presence of leucokinins in the abdominal nerve cord was confirmed by HPLC combined with ELISA. Leucokinin-immunoreactive neurosecretory cells were also found in the pars intercerebralis of the cricket Acheta domesticus and the mosquito Aedes aegypti, but not in the locust Schistocerca americana or the honey bee Apis mellifera. However, all these species have leucokinin-immunoreactive neurosecretory cells in the abdominal ganglia. The neurohemal organs innervated by abdominal leucokinin-immunoreactive cells were different in each species.
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    Ultrastructural examination of the insemination reaction in Drosophila (1994)
    Springer
    Cell & tissue research 275 (1994), S. 467-479 
    Details
    ISSN: 1432-0878
    Keywords: Vagina ; Insemination reaction ; Postmating behavior ; Evolution ; Sperm competition ; Sexual selection ; Paragonia ; Drosophila (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The insemination reaction is a swelling of the female vagina caused by the male ejaculate. This postmating phenomenon is common among species in the genus Drosophila. It could act as a plug securing male paternity. It is not clear, however, what benefits it provides to the female. The structure formed in the female vagina is expelled in some species and disappears gradually in others suggesting different phenomena. Based on ultrastructural examination of the vaginal contents of five Drosophila species (D. mettleri, D. nigrospiracula, D. melanogaster, D. mojavensis, and D. hexastigma), we propose three terms to describe these vaginal structures: the sperm sac, the mating plug, and the true insemination reaction. Each term describes a distinct structure associated with a specific female postmating behavior. This study questions the concept of the insemination reaction as a single phenomenon and discusses its possible functions from an evolutionary perspective.
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    URL: http://dx.doi.org/10.1007/BF00318816
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    Morphology and the evolution of cycadeoidales (1994)
    Springer
    Journal of plant research 107 (1994), S. 479-492 
    Details
    ISSN: 1618-0860
    Keywords: Cycadeoidales ; Evolution ; Gymnosperms ; Medullosales ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract OneCycadeoidea stem one cycadeoidalean gynoecium and a bisporangiate cone attached to a slender cycadeoidalean trunkCycadeoidella japonica Ogura from the Cretaceous of Japan shows well-preserved internal structure that provides evidence for a better understanding of the morphological architecture of the cycadeoidalean plant. Structural details of the cone were confirmed. The ovule has an intergument enclosing a free nucellus and a thin outer envelope. Both reproductive and vegetative structures support the medullosan affinity of Cycadeoidales. The cone is interpreted as a compressed fertile shoot. Axillary cones characterizing some Cretaceous genera such asCycadeoidea andMonanthesia consist of a lateral shoot subtended by a frond that is the first leaf of the cone shoot itself. The origin of axillary buds in the Cycadeoidales is discussed. Heterochrony may have mediated the morphological changes that resulted in the establishment of the Cycadeoidales.
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    Plasmodesmal-mediated cell-to-cell transport in wheat roots is modulated by anaerobic stress (1994)
    Springer
    Protoplasma 178 (1994), S. 81-85 
    Details
    ISSN: 1615-6102
    Keywords: Adenosine triphosphate ; Anaerobiosis ; Fluorescein-dextrans ; Plasmodesmata ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell-to-cell transport of small molecules and ions occurs in plants through plasmodesmata. Plant roots are frequently subjected to localized anaerobic stress, with a resultant decrease in ATP. In order to determine the effect of this stress on plasmodesmal transport, fluorescent dyes of increasing molecular weight (0.46 to 10 kDa) were injected into epidermal and cortical cells of 3-day-old wheat roots, and their movement into neighboring cells was determined by fluorescence microscopy. Anaerobiosis was generated by N2 gas or simulated by the presence of sodium azide, both of which reduced the ATP levels in the tissue by over 80%. In the absence of such stress, the upper limit for movement, or size exclusion limit (SEL), of cortical plasmodesmata was 〈1 kDa. The ATP analogue TNP-ADP (mw 681) moved across the plasmodesmata of unstressed roots, indicating that plasmodesmata may be conduits for nucleotide (ATP and ADP) exchange between cells. Upon imposition of stress, the SEL rose to between 5 and 10 kDa. This response of plasmodesmata to a decrease in the level of ATP suggests that they are constricted by an ATP-dependent process so as to maintain a restricted SEL. When roots are subjected to anaerobic stress, an increase in SEL may permit enhanced delivery of sugars to the affected cells of the root where anaerobic respiration could regenerate the needed ATP.
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    Volvocine cell walls and their constituent glycoproteins: An evolutionary perspective (1994)
    Springer
    Protoplasma 181 (1994), S. 245-258 
    Details
    ISSN: 1615-6102
    Keywords: Evolution ; Hydroxyproline-rich glycoprotein ; Cell wall ; Phylogenetics ; Chlamydomonas ; Volvocales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Similarities in the composition of the extracellular matrix suggest that only some species of the unicellularChlamydomonas are closely related to the colonial and multicellular flagellated members of the family Volvocaceae. The cell walls from all of the algae in this volvocine group contain a crystalline layer. This lattice structure can be used as a phylogenetic marker to divideChlamydomonas species into distinct classes, only one of which includes the volvocacean algae. Similarly, not all species ofChlamydomonas are sensitive to each other's cell wall lytic enzymes, implying divergence of the enzyme's inner wall substrate. Interspecific reconstitution of the crystalline layer is possible betweenC. reinhardtii and the multicellularVolvox carteri, but not betweenC. reinhardtii andC. eugametos. The hydroxyproline-rich glycoproteins (HRGPs) which make up the crystalline layer in genera which have a similar crystal structure exhibit many homologies. Interestingly, the evolutionarily distant cell walls ofC. reinhardtii andC. eugametos also contain some HRGPs displaying a few morphological and amino acid sequence homologies. The morphological similarities between the flagellar agglutinins (HRGPs responsible for sexual recognition and adhesion during the mating reaction) and the cell wall HRGPs leads to the proposal of a superfamily from which novel HRGPs (designed for self-assembly/recognition) can constantly evolve. Just as variations in the wall HRGPs can lead to unique wall structures, new agglutinins facilitate sexual isolation of new species. Thus, the HRGPs could emerge as valuable phylogenetic markers.
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    The role of suspended matter in the distribution of dissolved inorganic phosphate, iron and aluminium in the Ems estuary (1994)
    Springer
    Aquatic ecology 28 (1994), S. 383-395 
    Details
    ISSN: 1573-5125
    Keywords: Ems estuary ; phosphorus ; iron ; fluorescence ; aluminium ; adsorption ; suspended matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In winter 1992/1993, a persistent local maximum in fluorescence, dissolved iron, dissolved aluminium and dissolved inorganic phosphate was found, upstream of the turbidity maximum in the freshwater zone of the Ems estuary (The Netherlands — Federal Republic Germany; western Europe). Upstream of this local maximum values ranged from 6 to 9 rel. units fluorescence, 0.9 to 2.4 μmol dm−3 iron, 0.5 to 0.7 μmol dm−3 aluminium and 0.6 to 2.3 μmol dm−3 dissolved inorganic phosphate. Within the maximum peak values of 24 rel. units fluorescence, 5.8 μmol dm−3 iron, 1.4 μmol dm−3 aluminium and 8.3 μmol dm−3 dissolved inorganic phosphate were observed. Downstream, fluorescence (indicator of dissolved organic carbon) showed conservative mixing with sea water, whereas dissolved iron, aluminium and dissolved inorganic phosphate did not. Dissolved aluminium and iron were quickly removed from solution to reach values of ∼100 nmol dm−3 aluminium and ∼0.3 μmol·dm−3 Fe at salinities of approximately 7 PSU. Further seaward iron concentrations gradually decreased to levels below 0.04 μmol dm−3. Dissolved aluminium first decreased to ∼20 nmol dm−3 at 29 PSU and increased again to concentrations of 30–44 nmol dm−3 at higher salinities. Dissolved inorganic phosphate, however, first decreased to upstream concentrations before reaching a secondary peak in the mid-estuarine reaches. At salinities 〉25 PSU dissolved inorganic phosphate mixed conservatively with sea water. It is hypothesized that adsorption-desorption equilibria are responsible for the local maximum values of fluorescence (DOC), iron, aluminium and dissolved inorganic phosphate. The similarity between the observed curves suggests a common underlying process, possibly related to the adjustment of new equilibria between suspended matter of marine and riverine origin.
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    Science and selection (1994)
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    Biology and philosophy 9 (1994), S. 45-62 
    Details
    ISSN: 1572-8404
    Keywords: Evolution ; evolutionary epistemology ; Hull ; interactor ; progress ; replicator ; selection theory ; vehicle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract In this paper I consider the view that scientific change is the result of a selection process which has the same structure as that which drives natural selection. I argue that there are important differences between organic evolution and scientific growth. First, natural selection is much more constrained than scientific change; for example it is hard to populations of organisms to escape local maxima. Science progresses; it may not even make sense to say that biological evolution is progressive. Second, natural selection depends for its power on the specifics of its domain, so I doubt that there is much point in seeing a selective regime in science as an instance of a more general family of selective regimes. Third, the replicator/interactor distinction fits scientific change much less well than biological evolution. But a family of selective theories of science can be identified ranging from the very ambitious to the very modest. Though the very ambitious programs of evolutionary epistemology are in trouble, there is space for one which is not a trivial redescription of what everyone already knows, but which is sensitive to the peculiarities of its domain. That selective theory explains important aspects of the community organization of science, an organization which is central to scientific progress.
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    Determination of orthophosphate in highly saline waters (1994)
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    International journal of salt lake research 3 (1994), S. 159-173 
    Details
    ISSN: 1573-8590
    Keywords: phosphorus ; orthophosphate ; phosphomolybdenum blue ; salt effect ; hypersaline ; saline ; lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geography
    Notes: Abstract Standard methods for the determination of phosphorus as phosphate ion are now well established for fresh and marine waters. In highly saline waters, however, salt effects due to ionic strength, or to particular ions present, may result in method interferences. Three methods of analysis of phosphate based on the formation of phosphomolybdenum blue complexes have been evaluated here for hypersaline waters. Stannous chloride reduction in aqueous media exhibits a substantial salt effect and its use is not recommended. Stannous chloride reduction following extraction into non aqueous solvents shows a significant salt effect (up to 30 per cent) in solutions of salinity 〉100 g L−1. Dilution of hypersaline waters to below this salinity may overcome the salt effect but the method suffers from other disadvantages involving resource constraints and health and safety considerations. Ascorbic acid reduction, catalysed by antimony (III) ions, appears to offer the most promise for hypersaline waters. Turbidity in samples having high salinity (〉 100 g L−1) and high phosphorus concentrations (〉 500 μg P L−1) changes the spectral characteristics of solutions but linear calibration curves still result for concentrations in the range 400 to 1,000 μg P L−1. The occurrence of turbidity is also affected by the ionic composition of hypersaline waters since solutions made from sea salt give different results to those made from sodium chloride. Dilution of samples, to give salinities less than 100 g L−1 prior to reduction is recommended to avoid turbidity. The salt effect in these lower salinity waters is less than 3 per cent up to 100 g L−1.
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    Evaluation of various methods for the detection of barley yellow dwarf virus by the tissue-blot immunoassay and its use for virus detection in cereals inoculated at different growth stages (1994)
    Springer
    European journal of plant pathology 100 (1994), S. 71-80 
    Details
    ISSN: 1573-8469
    Keywords: wheat ; Triticum aestivum ; oat ; Avena sativa ; barley ; Hordeum vulgare ; serology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Various modifications of the tissue-blot immunoassay (TBIA) for the detection of barley yellow dwarf virus (BYDV, luteovirus) were compared. Similar results were obtained by using three different labelled molecules; goat anti-rabbit antibodies conjugated to alkaline phosphatase, protein A conjugated with alkaline phosphatase and goat anti-rabbit antibodies conjugated with colloidal gold. Blocking the nitrocellulose membrane with polyvinyl alcohol for 1 min was effective and allowed the procedure to be shortened by one hour. TBIA was sensitive enough to detect BYDV in old dry tissue wich had been soaked in water for 1 h. BYDV was monitored by TBIA in wheat, oat and barley after inoculation at heading, flowering and grain filling growth stages. The later the inoculation date, the greater the chance of detecting the virus in stem bases rather than in the upper part of the stem. The later the inoculation the less virus moved, from the inoculated tiller to other tillers of the same plant.
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    Widespread occurrence of the Tc1 transposon family: Tc1-like transposons from teleost fish (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 606-612 
    Details
    ISSN: 1617-4623
    Keywords: Evolution ; Vertical transmission ; Phylogenetic relationships ; Transposable element Transposase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We characterized five transposable elements from fish: one from zebrafish (Brachydanio rerio), one from rainbow trout (Salmo gairdneri), and three from Atlantic salmon (Salmo salar). All are closely similar in structure to the Tel transposon of the nematode Caenorhabditis elegans. A comparison of 17 Tc1-like transposons from species representing three phyla (nematodes, arthropods, and chordates) showed that these elements make up a highly conserved transposon family. Most are close to 1.7 kb in length, have inverted terminal repeats, have conserved terminal nucleotides, and each contains a single gene encoding similar poly peptides. The phylogenetic relationships of the transposons were reconstructed from the amino acid sequences of the conceptual proteins and from DNA sequences. The elements are highly diverged and have evidently inhabited the genomes of these diverse species for a long time. To account for the data, it is not necessary to invoke recent horizontal transmission.
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    Chloroplast DNA variation and the phylogeny ofAsplenium sect.Hymenasplenium (Aspleniaceae) in the New World tropics (1994)
    Springer
    Journal of plant research 107 (1994), S. 245-251 
    Details
    ISSN: 1618-0860
    Keywords: Aspleniaceae ; Asplenium sect.Hymenasplenium ; Chloroplast DNA ; Evolution ; Molecular phylogeny ; New World tropics ; Restriction site variation analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Asplenium sect.Hymenasplenium is a well-defined group in Aspleniaceae, distinguished by several morphological and cytological characters. However, interspecific relationships in the section were not clear. In this paper, we report the phylogenetic relationships of 9 Neotropical species of sect.Hymenasplenium determined by chloroplast DNA restriction site variation analyses. From the obtained phylogenetic tree, two major clades: one withA. obtusifolium, A. riparium, A. volubile andA. repandulum and another withA. delitescens, A. ortegae, A. purpurascens, A. laetum andA. hoffmannii were recognized.Asplenium delitescens was shown to have a polyphyletic origin. It was also shown that the epiphytic habit evolved only once in the New World species of sect.Hymenasplenium.
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    Growth and elemental content of several sagebrush-steppe species in unburned and post-wildfire soil and plant effects on soil attributes (1994)
    Springer
    Plant and soil 164 (1994), S. 35-41 
    Details
    ISSN: 1573-5036
    Keywords: nitrogen ; phosphorus ; revegetation ; silica ; succession ; shrubland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fire is the principal means of stand renewal in big sagebrush-steppe communities of western North America. Plant growth following fire may be influenced by heat-induced changes in the nutrient status of the soil. Moreover, post-wildfire pioneer plant species may alter soil properties, and thereby, impact subsequent plant recruitment. Our study compared the growth and elemental content of big sagebrush (Artemisia tridentata), squirreltail (Elymus elymoides), cheatgrass (Bromus tectorum), and Indian ricegrass (Achnatherum hymenoides), grown under greenhouse conditions in post-wildfire and similar unburned soil. We also examined soil attributes following plant growth. Cheatgrass and squirreltail, grown in post-wildfire soil, had significantly (p≤0.05) greater aboveground mass than plants grown in unburned soil. As compared with unburned soil, post-wildfire soil engendered the following significant (p≤0.05) differences in leaf elemental content: 1) big sagebrush had higher levels of P and lower levels of Mn; 2) squirreltail accumulated more P and N; and 3) all grass species had higher SiO2 content. Following harvest of plants, post-wildfire soil generally contained significantly (p≤0.05) more KCl-extractable ortho-P, NH inf4 + , and SO 4 − , than unburned soil. Plant growth in both burned and unburned soils fostered a significant (p≤0.05) increase in the bicarbonate-extractable pool of P as compared with unplanted controls. Soil Kjeldahl-N was significantly (p≤0.05) greater after plant growth in burned treatments as compared with the control. This study demonstrates that post-wildfire soil can have a stimulatory effect on plant growth for some species. Squirreltail deserves consideration as a post-wildfire revegetation species. Furthermore, pioneer plant growth following wildfires can attenuate soil properties and therefore influence plant succession.
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    URL: http://dx.doi.org/10.1007/BF00010108
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    Subterranean clover decline in permanent pastures in north-eastern Victoria (1994)
    Springer
    Plant and soil 164 (1994), S. 231-241 
    Details
    ISSN: 1573-5036
    Keywords: phosphorus ; root disease ; soil acidity ; subterranean clover ; yield decline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experimental sites were established at two locations in north-eastern Victoria to define factors limiting the establishment and growth of Trifolium subterranean L. (subterranean clover). Liming the soil, seed inoculation and fungicide application were used in renovating subterranean clover pasture on two acidic soils (Longwood: brown/grey sandy loam DY 3.14 and Seymour: grey brown light clay DY 3.22, Northcote classification) with mean annual rainfall of 650 mm and 600 mm respectively. Soil acidity, low available soil phosphorus and plant disease were identified as factors limiting clover yield on these soils. Significant yield responses to lime (35–140%) were obtained with subterranean clover at both sites, with corresponding decreases in Al in the 0–10 cm soil horizon. Liming the soil, when combined with seed inoculation, increased the number and effectiveness of root nodules at both sites. Soil P available for plant growth was low at both sites (6.1 and 8.4 μg g−1) resulting in sub-optimal P concentrations in the clover herbage (45 mmol kg−1 at Longwood). Levels of root disease were low but Aphanomyces euteiches and Phytophthora clandestina (causal agents of lateral and tap root rot) were detected frequently on roots. Application of fungicide resulted in higher dry matter yields (p=0.05) at both sites. An assessment of the relative contributions of these limiting factors and the benefits to be obtained from better management would provide a clearer picture of the profitability and sustainability of this farming system.
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    URL: http://dx.doi.org/10.1007/BF00010075
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    Phosphorus depletion in the rhizosphere as influenced by soil moisture (1994)
    Springer
    Plant and soil 159 (1994), S. 213-218 
    Details
    ISSN: 1573-5036
    Keywords: concentration gradient ; diffusion ; phosphorus ; rhizosphere ; soil moisture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To study the influence of soil moisture on phosphorus (P) depletion in the rhizosphere, maize (Zea mays cv. Trak) was pre-grown in vermiculite filled-PVC tubes for 9 days and then the plants with the tubes were transplanted into soil columns maintained at two soil moisture levels (θ) of 0.14 and 0.20 cm3 cm−3 for 10 days. The soil columns were separated at 1 cm depth by a nylon screen of 53 μm inner mesh size, into 1 cm soil layer above and 3 cm soil column below screen. A root mat developed over the screen, but root hairs only could penetrate it. Regardless of the soil moisture level in the columns, and adequate and equal water and nutrients supply was maintained via wicks from an external nutrient solution to the plant roots in vermiculite. After 10 days, the soil columns were separated from the root mats, quickly frozen in liquid nitrogen and sliced into thin layers (0.2mm) using a refrigerated microtome to give soil samples at defined distances from the root mats for analyses. Lower soil moisture (θ=0.14) resulted in narrower and steeper depletion profile of 0.5 M NaHCO3 extractable P (NaHCO3-Pi) as compared to higher soil moisture (θ=0.20). Depletion of P in soil solution in the immediate vicinity of root mats did not differ much but the extension of the depletion zones was 0.10 cm at θ=0.14 and 0.20 cm at θ=0.20. The depletion up to 0.05cm with θ=0.14 and up to 0.07 cm with θ=0.20 was uniform, and may be attributed to the depletion in the root hair zone. Beyond the root hair zones, the theory of diffusion and mass flow was able to explain the observed differences in shape and extent of the P depletion profiles at the two soil moisture levels.
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    URL: http://dx.doi.org/10.1007/BF00009283
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    Effect of elevated CO2 on mycorrhizal colonization of loblolly pine (Pinus taeda L.) seedlings (1994)
    Springer
    Plant and soil 165 (1994), S. 81-88 
    Details
    ISSN: 1573-5036
    Keywords: carbohydrates ; ectomycorrhizae ; elevated CO2 ; phosphorus ; Pinus taeda L. ; Pisolithus tinctorius (Pers.) Coker & Couch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Interactive effects of elevated atmospheric CO2 and phosphorus supply on mycorrhizal colonization rates were investigated using loblolly pine (Pinus taeda L.) seedlings from Florida and coastal North Carolina. Seedlings from both populations were grown in greenhouses maintained at either 35.5 Pa or 71.0 Pa CO2. In both CO2 treatments, seedlings were grown in a full factorial experiment with or without mycorrhizal inoculum and with an adequate or a limiting supply of phosphorus. Seedlings were harvested 60, 90 and 120 days after emergence and at each harvest root subsamples were examined to determine the percent of fine roots that were mycorrhizal. Additionally, root carbohydrate and nutrient levels were measured at each harvest. Root starch, sugar and total non-structural carbohydrate (TNC) concentrations were increased by growth in elevated CO2 and decreased by mycorrhizal colonization. Phosphorus stress decreased root starch concentrations, increased root sugar concentrations and did not significantly affect TNC concentrations. However, despite significant effects on root carbohydrate levels, there were generally no significant treatment effects on mycorrhizal colonization. Additionally, at all harvests, root starch and sugar concentrations were not correlated with percent of fine roots that were mycorrhizal. These results suggest that although elevated CO2 may significantly increase root carbohydrate levels, the increases may not affect the percent of fine roots that are mycorrhizal.
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    URL: http://dx.doi.org/10.1007/BF00009965
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    Enhanced root system C-sink activity, water relations and aspects of nutrient acquisition in mycotrophic Bouteloua gracilis subjected to CO2 enrichment (1994)
    Springer
    Plant and soil 165 (1994), S. 139-146 
    Details
    ISSN: 1573-5036
    Keywords: blue grama ; Bouteloua gracilis ; C4 grass ; CO2 enrichment ; mycorrhizae ; nitrogen ; phosphorus ; VAM ; water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to better elucidate fixed-C partitioning, nutrient acquisition and water relations of prairie grasses under elevated [CO2], we grew the C4 grass Bouteloua gracilis (H.B.K.) lag ex Steud. from seed in soil-packed, column-lysimeters in two growth chambers maintained at current ambient [CO2] (350 μL L−1) and twice enriched [CO2] (700 μL L−1). Once established, plants were deficit irrigated; growth chamber conditions were maintained at day/night temperatures of 25/16°C, relative humidities of 35%/90% and a 14-hour photoperiod to simulate summer conditions on the shortgrass steppe in eastern Colorado. After 11 weeks of growth, plants grown under CO2 enrichment had produced 35% and 65% greater total and root biomass, respectively, and had twice the level of vesicular-arbuscular mycorrhizal (VAM) infection (19.8% versus 10.8%) as plants grown under current ambient [CO2]. The CO2-enriched plants also exhibited greater leaf water potentials and higher plant water use efficiencies. Plant N uptake was reduced by CO2 enrichment, while P uptake appeared little influenced by CO2 regime. Under the conditions of the experiment, CO2 enrichment increased root biomass and VAM infection via stimulated growth and adjustments in C partitioning below-ground.
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    URL: http://dx.doi.org/10.1007/BF00009970
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    Growth response and phosphorus uptake of rye with long and short root hairs: Interactions with mycorrhizal infection (1994)
    Springer
    Plant and soil 167 (1994), S. 247-254 
    Details
    ISSN: 1573-5036
    Keywords: efficiency ; Glomus intraradices ; phosphorus ; root hair ; rye ; Secale cereale L. ; VA mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant growth and phosphorus (P) uptake of two selections of rye (Secale cereale L.) differing in length of root hairs, in response to mycorrhizal infection were investigated. Rye plants with short root hairs (SRH) had a greater length of root infected by Glomus intraradices (up to 32 m pot−1) than those with long root hairs (LRH) (up to 10 m pot−1). Application of P decreased the percentage of root length infected in both selections. In low-P soil, mycorrhizal infection increased shoot and root P concentration, especially in LRH plants. Generally, LRH had higher shoot dry weight than SRH plants. P uptake was increased both by LRH and by mycorrhizal infection. Differences in specific P uptake and P utilization efficiency between SRH and LRH plants were observed in non-mycorrhizal plants. With low P supply, P utilization efficiency (dry matter yield per unit of P taken up) of LRH plants increased with time. However, mycorrhizal infection reduced P utilization efficiency, particularly of SRH plants. SRH plants, which were agronomically less efficient (i.e. low dry matter yield at low P supply) were more responsive to either mycorrhizal infection or P addition than the LRH plants. No interaction was observed between mycorrhizal infection and root hair length.
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    URL: http://dx.doi.org/10.1007/BF00007951
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    Genetic basis of grain filling rate in wheat (Triticum aestivum L. emend. Thell.) (1994)
    Springer
    Euphytica 76 (1994), S. 33-44 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; genetic basis ; grain filling rate ; genetic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P 〈 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P 〈 0.001) in LE and WPE. It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.
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    URL: http://dx.doi.org/10.1007/BF00024018
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    Characterisation and origin of rust and powdery mildew resistance genes in VPM1 wheat (1994)
    Springer
    Euphytica 76 (1994), S. 53-61 
    Details
    ISSN: 1573-5060
    Keywords: stripe rust ; stem rust ; leaf rust ; powdery mildew ; common wheat ; environmental effects ; Puccinia striiformis ; Puccinia graminis ; Puccinia recondita ; Erysiphe graminis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The expression of rust resistances conferred by closely linked genes derived from VPM1 varied with environmental conditions and with genetic backgrounds. Under low light and low temperature conditions seedlings carrying Yr17 showed susceptible responses. Stem rust and leaf rust resistance genes Sr38 and Lr37 tended to confer more resistance at 17±2° C than at normal temperatures above 〉 20° C. These studies supported the hypothesis that Yr17, Lr37 and Sr38 were derived from Aegilops ventricosa, whereas Pm4b was probably derived from T. persicum. Studies on certain addition lines and parental stocks indicated that wheat cytoplasm may enhance the expression of Sr38.
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    URL: http://dx.doi.org/10.1007/BF00024020
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    Nutrient uptake in eastern deciduous tree seedlings (1994)
    Springer
    Plant and soil 160 (1994), S. 193-199 
    Details
    ISSN: 1573-5036
    Keywords: gaps ; ion uptake ; nitrogen ; nutrient acquisition ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Tree seedlings that colonize large treefall gaps are generally shade-intolerant species with high potential relative growth rates. Nutrient availability may be significantly elevated in disturbance-induced gaps, however, little is known about the role of differences in nutrient uptake capacities of different species in structuring the community response to gap openings in eastern North American deciduous forests. Seven tree species were grown from seed under both a high and a low nutrient regime, and uptake kinetics of phosphate, ammonium, and nitrate were studied. Yellow birch, a species with intermediate shade tolerance and relative growth rate, had the highest maximum rates of uptake of all ions, while tulip tree, a gap-colonizing species with high relative growth rate, had the lowest rate of phosphate uptake and intermediate rates of ammonium and nitrate uptake. Beech and hickory, which have low relative growth rates and are not gap-colonizing species, had intermediate levels of nutrient uptake. There was no evidence that species with the highest maximum uptake rates measured at high supply concentrations had relatively low uptake at low nutrient supply concentrations. Although birch increased phosphate absorption capacity when grown under a low nutrient regime, this pattern did not hold for nitrate or ammonium uptake, and other species showed no change in nutrient uptake capacity according to nutrient growth regime. Clearly, factors other than nutrient absorption capacity, such as nutrient use efficiency or allocation to root vs. shoot biomass, underlie differences in species' capacities to colonize and maintain a high relative growth rate in canopy gaps.
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    URL: http://dx.doi.org/10.1007/BF00010145
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    Carbon cost of root systems: an architectural approach (1994)
    Springer
    Plant and soil 165 (1994), S. 161-169 
    Details
    ISSN: 1573-5036
    Keywords: carbon cost ; phosphorus ; Phaseolus vulgaris ; root architecture ; root growth ; root simulation model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root architecture is an important component of nutrient uptake and may be sensitive to carbon allocational changes brought about by rising CO2. We describe a deformable geometric model of root growth, SimRoot, for the dynamic morphological and physiological simulation of root architectures. Using SimRoot, and measurements of root biomass deposition, respiration and exudation, carbon/phosphorus budgets were developed for three contrasting root architectures. Carbon allocation patterns and phosphorus acquisition efficiencies were estimated for Phaseolus vulgaris seedlings with either a dichotomous, herringbone, or empirically determined bean root architecture. Carbon allocation to biomass, respiration, and exudation varied significantly among architectures. Root systems also varied in the relationship between C expenditure and P acquisition, providing evidence for the importance of architecture in nutrient acquisition efficiency.
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    URL: http://dx.doi.org/10.1007/BF00009972
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    Effects of growth period, plant age and changes in solution aluminium concentrations on aluminium toxicity in wheat (1994)
    Springer
    Plant and soil 166 (1994), S. 21-30 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; growth period ; phosphorus ; plant age ; root length ; root width ; solution culture ; techniques ; Triticum aestivum ; variation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of growth period (time between transplanting and harvesting), plant age at which aluminium (Al) was added to solution, changes in Al concentration, and solution culture techniques (monitoring and adjusting solution Al concentrations thrice weekly or weekly replacement of the solutions) were investigated using a low ionic strength (2.7×10−3 M) solution culture technique. The wheat (Triticum aestivum L.) cultivars Waalt (Al-tolerant) and Warigal (Al-sensitive), or the near isogenic lines bred from these cultivars (RR for the Al-tolerant line and SS for the Al-sensitive line) were grown. In all experiments and treatments, Al additions were required to maintain the nominal concentration. The decline in solution Al concentrations was partially attributed to formation of an Al-hydroxy-phosphate precipitate with an Al:P molar ratio of 2.8 to 4.0. Increasing the growth period from 14 to 28 days increased Al sensitivity in Warigal but not in Waalt. When plants were exposed to Al for the same time, increasing the age of the plants that Al was added to solution decreased sensitivity to Al. Differential Al tolerance between the two lines was evident when solutions were monitored thrice weekly or replaced weekly. However, the Al concentration required to reduce relative yield by a given amount when the solutions were replaced weekly was about twice that when the solutions were monitored. With a constant growth period of 28 days, increasing solution Al concentrations for 3 or more days resulted in decreased yields at harvest. The exact effect depended on the cultivar, plant part (tops or roots), when solution Al concentrations were increased and the duration of the increase. For example, increasing Al concentrations from 5 μM to 20 μM for 10 days reduced yield in the RR line by approximately 50% in the tops and 30% in the roots beyond the effect of 5 M but had no effect in the SS line due to yields already being low at 5 μM. Adding 10 μM Al to solution for 6 days at the beginning of the experiment reduced yield by 25% in the RR line and 50% in the SS line. In contrast, adding 10 μM Al for 6 days in the middle of the growth cycle had no effect on the RR line but reduced yield by approximately 25% in the SS line. These results show that growth period, the age of the plants at which Al is added and the technique used (monitored or weekly replacement) all need to be considered when comparing results from different experiments. These results also show that the Al concentrations in solution need to be regularly monitored in long term experiments.
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    URL: http://dx.doi.org/10.1007/BF02185477
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    Colonisation of wheat by VA-mycorrhizal fungi was found to be higher on a farm managed in an organic manner than on a conventional neighbour (1994)
    Springer
    Plant and soil 160 (1994), S. 33-40 
    Details
    ISSN: 1573-5036
    Keywords: organic agriculture ; phosphorus ; rock phosphate ; VA-mycorrhizas ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Levels of colonisation by vesicular-arbuscular (VA)-mycorrhizal fungi were compared between adjacent farms, one operated in a conventional manner and the other run according to organic farming principles. Wheat grown on the organic farm was found to have VA-mycorrhizal colonisation levels consistently 2 to 3 times higher than wheat on the conventional farm. Glasshouse and field trials indicated that the lower colonisation levels on the conventional farm were due to continual use of fertiliser containing soluble phosphorus (P). The fertiliser appeared to have an immediate negative effect on the rate of colonisation, and also appeared to have a long term negative effect through maintaining higher levels of soluble P in the soil, and by decreasing inoculum levels. Use of the relatively insoluble reactive rock phosphate fertiliser on the organic farm did not decrease levels of VA-mycorrhizas. Colonisation levels did not vary between wheat varieties, and herbicides and seed dressings were also not found to be having any significant effect on levels of colonisation.
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    URL: http://dx.doi.org/10.1007/BF00150343
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    C-band polymorphism and structural rearrangements detected in common wheat (Triticum aestivum) (1994)
    Springer
    Euphytica 78 (1994), S. 1-5 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; C-band polymorphism ; structural rearrangements ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Giemsa C-banding allows for the identification of all 21 chromosome pairs of hexaploid wheat. However, variation in banding patterns of individual chromosomes and structural rearrangements exist between different cultivars making chromosome identification more difficult. The paper summarizes the available data on C-band polymorphism and structural rearrangement present in wheat cultivars and germplasms.
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    URL: http://dx.doi.org/10.1007/BF00021392
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    The effect of temperature on seed set and embryo development in reciprocal crosses of wheat and barley (1994)
    Springer
    Euphytica 78 (1994), S. 53-58 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Hordeum vulgare ; barley ; intergeneric hybridization ; influence of temperature ; embryo development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of temperature on seed set and embryo development in reciprocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvásári 50) and one wheat variety (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled environments at constant day-night temperature regimes (12, 15, 18 and 21° C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15° C) produced the maximum seed set, whereas for the reciprocal cross, the highest temperature (21° C) produced the best seed set in the Chinese Spring × Betzes combination. Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18° C and 21° C in the barley × wheat cross and in the wheat × barley cross, respectively. Embryos of about 1.5 mm length in the barley × wheat cross, and of about 1.0 mm length in the wheat × barley cross germinated successfully. The smallest embryo giving rise to hybrid plants was 0.57 mm in the barley × wheat cross and 0.51 mm in the wheat × barley cross.
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    URL: http://dx.doi.org/10.1007/BF00021397
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    Nutrient balances and phytoplankton dynamics in two agriculturally loaded shallow lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 359-369 
    Details
    ISSN: 1573-5117
    Keywords: agriculture ; blue-green algae ; eutrophication ; internal loading ; nitrogen ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The impact of agriculture was estimated on two shallow, eutrophic lakes, Lake Kotojärvi and Lake Villikkalanjärvi in southern Finland. The main emphasis was on phosphorus and nitrogen budgets and on the phytoplankton dynamics. Special attention was paid to internal P loading and blue-green algal blooms. The mean Tot-P load from agricultural land was 1.2 kg ha-1 a-1 in both basins and Tot-N loads were 19 kg ha-1 a-1 in L. Villikkalanjärvi and 12 kg ha-1 a-1 in L. Kotojärvi. The Tot-P input to L. Kotojärvi was on an average 0.62 g m-2 a-1 (per lake surface area), and the Tot-N input 9.1 g m-2 a-1. The corresponding inputs to L. Villikkalanjärvi were 3.1 and 57 g m-2 a-1, respectively. The annual variation followed the runoff volumes. About half of the Tot-P and one third of the Tot-N load was retained in L. Kotojärvi. In L. Villikkalanjärvi the retention was only 24% for Tot-P and 19% for Tot-N. The difference was very probably due to a longer theoretical retention time in L. Kotojärvi. In L. Villikkalanjärvi the mean concentration of Tot-P was 120 µg 1-1 and that of Tot-N 1700 µg 1-1 and the corresponding figures in L. Kotojärvi 67 and 990 µg 1-1, respectively. The mean chlorophyll a concentration was, however, higher in L. Kotojärvi (26 µg 1-1) than in L. Villikkalanjärvi (20 µg 1-1). This was probably due to an internal P load in L. Kotojärvi: in 1988 the internal load of dissolved P was estimated to be as much as twofold the external load. In L. Villikkalanjärvi the internal dissolved P load was only up to 50% of the external input. In L. Kotojärvi the high internal P load coupled with a low DIN:DIP ratio resulted in a strong blue-green algal bloom in the summer of 1988. In L. Villikkalanjärvi blue-green algae were observed only in small amounts. Even in August 1990, when the DIN:DIP ratio was low enough to favor the occurrence of blue-green algae, they contributed only up to 10–15% of the total phytoplankton biomass.
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    URL: http://dx.doi.org/10.1007/BF00026726
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    A diatom-phosphorus transfer function for shallow, eutrophic ponds in southeast England (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 391-410 
    Details
    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; palaeolimnology ; transfer function ; United Kingdom ; shallow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Shallow ponds in southeast England are often eutrophic with high phosphorus concentrations. The aim of this study was to develop a diatom-phosphorus ‘transfer function’ to enable past phosphorus levels in such waters to be inferred from the sediment record. A water chemistry survey of 123 randomly chosen, shallow, artificial ponds in southeast England was carried out. Principal components analysis (PCA) revealed that phosphorus was an important environmental variable. A subset of 31 sites was selected along a total phosphorus (TP) gradient (winter TP range 7–1123 µg 1-1), in order to explore the relationship between the surface-sediment diatom assemblages and the contemporary water chemistry using canonical correspondence analysis (CCA). Annual mean TP was the most significant variable in explaining the variance in the diatom species data. Weighted averaging (WA) regression and calibration techniques were used to generate a transfer function, enabling annual mean TP (range 25–646 µg 1-1) to be inferred from the diatom species TP optima of 102 common taxa in the dataset (r 2 = 0.79; RMSE = 0.161; RMSE(boot) = 0.279; n = 30). The model was applied to fossil diatom assemblages in a sediment core from Marsworth Reservoir, Hertfordshire, a Site of Special Scientific Interest (SSSI), with currently high TP levels of 476 µg 1-1, to reconstruct past epilimnetic annual mean TP concentrations. The study shows that artificial, shallow waters can be suitable for palaeolimnological research and that it is possible to reliably infer lake water TP using the WA technique, across a large range of phosphorus concentrations. This method has the potential to provide limnologists, conservationists and water quality managers with an estimate of pre-enrichment phosphorus concentrations and an indication of the onset and development of eutrophication at a site. This information is essential for lake management strategies and restoration programmes.
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    URL: http://dx.doi.org/10.1007/BF00026729
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    Nutrient metabolism (C, N, P, and Si) in the trophogenic zone of a meromictic lake (1994)
    Springer
    Hydrobiologia 277 (1994), S. 17-39 
    Details
    ISSN: 1573-5117
    Keywords: carbon ; phosphorus ; nitrogen ; silica ; sedimentation ; mineralization ; meromixis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The dynamics of seston and dissolved elements in a meromictic lake with high concentrations of manganese and iron in the monimolimnion were studied through an annual cycle. This publication presents results for assimilation, sedimentation and recovery of nutrients (C, N, P, and Si) in the trophogenic zone. Phosphorus deficiency kept the productivity of the diatom dominated phytoplankton at an oligotrophic level. High concentrations of iron in influent streams and redistribution followed by precipitation of iron during periods of partial turnover removed phosphorus from the water. High concentrations of manganese and sulfate did not have the anticipated fertilizing effect, and recovery of nutrients from the depth of the lake was negligible. Mass balance calculations indicate that liberation of phosphorus from the sediments in the trophogenic zone was most important for the maintenance of primary production. 75% of carbon, 80% of nitrogen and 25% of phosphorus assimilated by the phytoplankton was mineralized in the trophogenic zone. Silica was effectively regenerated from the littoral zone during the decline of diatom blooms. Nitrogen and silica retention was 45% of the external load compared to 66% for phosphorus.
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    URL: http://dx.doi.org/10.1007/BF00023983
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    The importance of avian-contributed nitrogen (N) and phosphorus (P) to Lake Grand-Lieu, France (1994)
    Springer
    Hydrobiologia 279-280 (1994), S. 133-147 
    Details
    ISSN: 1573-5117
    Keywords: eutrophication ; birds ; lake ; nitrogen ; phosphorus ; eutrophisation ; oiseaux ; lac ; azote ; phosphore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le plus grand lac de plaine français, Grand-Lieu, est actuellement largement eutrophisé. Le but de cette étude est d'estimer l'importation annuelle de N et P par les fientes des oiseaux qui s'alimentent à l'extérieur du lac, et de la comparer avec les apports des rivières alimentant le lac. Deux années sont comparées: 1981–82 et 1990–91. Les populations nicheuses (jusqu'à 956 couples de hérons cendrés et 136 couples de grands cormorans et 30 000 canards) et hivernantes (jusqu'à 17 000 canards, 1100 grands cormorans, 15 000 goélands et 2,4 millions d'étourneaux) ont respectivement importé 5800 kg de N total en 1981–82 et 7640 en 1990–91, soit 0,7% et 0,4% des entrées totales du système, et 2000 à 2530 kg de P total soit 2,4 et 6,6% des entrées. Les étourneaux sont responsables des trois quarts des apports d'azote par les oiseaux, et les canards de l'essentiel du reste, tandis que la part des étourneaux baisse pour le phosphore (36% en 1981–82 et 41% en 1990–91), au profit des Canards et des Hérons (respectivement 35% et 27% en 1981–82, 22% et 24% en 1990–91). Mais pendant la phase de croissance végétale (avril–septembre), la part des oiseaux monte jusqu'à 37% des entrées totales de phosphore. L'action localisée des colonies d'oiseaux piscivores est significative, avec une teneur de phosphore 42 fois plus grande dans l'eau sous la colonie qu'à l'extérieur des colonies. A l'échelle du l'ac, l'action actuelle globalement mineure des oiseaux sur les apports totaux d'azote et de phosphore est largement due à l'augmentation catastrophique des apports d'origine humaine (agriculture intensive et stations d'épuration). La teneur moyenne des rivières atteint désormais 10 mg l−1 de N (jusqu'à 23 mg en crue) et 394 mg m−3 de P (jusqu'à 468 mg en crue). Avant cette pollution généralisée, l'eau des rivières bretonnes ne contenait dans les années 1960 que 0,1 à 1,1 mg l−1 de N et 1 à 5 mg m−3 de P lors des périodes de débits maximum. A cette époque, les oiseaux représentaient probablement jusqu'à 36% des apports de N et 95% des apports de P dans les entrées du système lacustre.
    Notes: Abstract The largest natural lake in France, Grand-Lieu, has suffered eutrophication. The objective of the study was to estimate the annual input of nutrients (N, P) resulting from avian excrement, deposited by birds feeding out of the lake and returning to its waters for breeding or roosting, as compared to the input by the rivers that enter in the lake. Two years are compared: 1981–82 and 1990–91. About 1600–2000 breeding herons and cormorants, 20 000–33 000 wintering ducks, gulls and cormorants and 1–2.4 million starlings deposited about 5800 kg total N in 1981–82 and 7640 kg in 1990–91. Respectively, 2000 and 2530 kg total P were deposited over the same time periods. These represent 0.7% and 0.4% of the total N input of the lake and 2.4 and 6.6% of the total P input in 1981–82 and 1990–91. Starlings account for 74% of the N and mallards most of the rest. P input by starlings (36% in 1981–82, 41% in 1990–91), and by mallards and herons (35% and 27% in 1981–82 and 22% and 24% in 1990–91 respectively) plays an appreciable role among birds. During the plant growing period (April–September), the contribution by birds can increase to 37% of total P input of the lake. Piscivorous bird colonies concentrate Phosphorus 42 times more within the colony than outside the colony. Overall, the role birds play in total N and P input is relatively small due to very high inputs from human sewage and agriculture run off. The monthly mean concentration of the water of the two rivers reaches currently 10 mg l−1 of N (to 23 mg during peak floods) and 394 mg m−3 of P (to 468 mg during peak floods). Earlier, for example in the 1960's, water in Brittany only contained 0.1 to 1.1 mg 1−1 of N and 1 to 5 mg m−3 of P during the maximum flow period. At this time, birds could probably have represented annually up to 37% of the N input and up to 95% of the P input to the lake.
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    Different responses to changes in phosphorus, P, among lakes. A study of slopes in chl-a = f(P) graphs (1994)
    Springer
    Hydrobiologia 286 (1994), S. 27-36 
    Details
    ISSN: 1573-5117
    Keywords: Lake ; eutrophication ; phytoplankton ; phosphorus ; non-linear interpolation ; chlorophyll-a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The least squares estimator of a linear regression coefficient βL will give an overall expression for the change in Δ with Δx. In fresh water ecology, however, subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\], of a parent population may have slopes which differ from the overall slope, βκ ≠ βL. By constructing frequency histograms for the set of angles: Arctang % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\],% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaci4uaSGaam% yAaiaadQgaaaa!38AE!\[\operatorname{S} ij\]= para sa y and x% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaadM% faliaadMgakiabgkHiTiaadMfaliaadQgakiaacMcacaGGVaGaaiik% aiaadIhaliaadMgakiabgkHiTiaadIhaliaadQgakiaacMcaaaa!42F0!\[(Yi - Yj)/(xi - xj)\], i 〈 j, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEaSGaam% yAaOGaeyiyIKRaamiEaSGaamOAaaaa!3BAB!\[xi \ne xj\], peaks in the distribution may be identified and related to ecological phenomenon. To identify peaks we fit Gaussian distributions to the frequency histograms. For a set consisting of 142 observations of chlorophyll-a and total phosphorus (nutrient) concentrations (TP) from 16 lakes we found four Gaussian peaks corresponding to four subgroups, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiuaSGaci% 4Aaaaa!37BE!\[P\operatorname{k}\]k = 1,4. One group identified a response of chl-a to changes in TP which correspond approximately to the average slope found by least square regression (the slope was 0.49). The second group consisted of steeper response than the average (1.28). A third group showed that there is an enhanced proportion of cases where chl-a does not respond to TP (zero slope, all the three deep lakes 〉 10 m, included in the date set contributed to this group). The size of the last group, spanning a wide range of slopes, suggested that about 30% of the inter annual changes in chl-a is unrelated to TP. The results are compared to result obtained by simple least squares regression and to the Theil non-parametric slope estimator.
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    Chlorophyll-phosphorus relationship in acidified lakes of the High Tatra Mountains (Slovakia) (1994)
    Springer
    Hydrobiologia 274 (1994), S. 171-177 
    Details
    ISSN: 1573-5117
    Keywords: chlorophyll ; phosphorus ; mountain lakes ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Concentrations of total phosphorus (TP) and chlorophyll a (CHLA) were measured in 28 lakes in the High Tatra Mountains (Slovakia) from 1983 to 1990. The relationship between log CHLA and log TP in the Tatra lakes is similar to relationships developed for lakes in other regions, but variation is higher. A part of this variation is caused by acidification of the lakes. In the lakes with pH between 4.9 and 6.3 the CHLA concentrations are often extremely low while TP concentrations decreased, but not as drastically.
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    URL: http://dx.doi.org/10.1007/BF00014640
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    Nutrient cycling in shallow, oligotrophic Lake Kvie, Denmark (1994)
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    Hydrobiologia 275-276 (1994), S. 267-276 
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    ISSN: 1573-5117
    Keywords: phosphorus ; redox potential ; sediment ; rhizosphere ; macrophyte ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The importance of isoetids for the exchange of phosphorus between sediment and water was studied in the shallow Lake Kvie, Denmark. Vegetated sediments from the littoral zone (55% of lake area) were compared to unvegetated sediments from the littoral and profundal zone. Porewater concentration of soluble reactive phosphate (SRP) was in general low, however, different distributions were found in the three sediments. The vegetated littoral sediment showed highest conc. of SRP just below the surface and decreasing conc. with sediment depth. The SRP release was low on all stations ( 〈 40 µmol m-2 d-1). The observed release of SRP on the vegetated station was much lower than the calculated diffusional flux probably due to assimilation of P by isoetids and binding of SRP to oxidized Fe. The high redox potential in the rhizosphere was probably caused by oxygen excretion from roots. The annual P release from vegetated sediments were only 5% of the P requirements of the macrophytes. The efficient plant assimilation of SRP from the porewater resulted in a small SRP pool with a very fast turnover of P of 500–900 times per year. Both the effects of isoetids on the P cycle in littoral sediments and on the P budget of the entire lake indicate that this plant group is important for keeping lakes in an oligotrophic state.
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    Can Chara control phosphorus cycling in Lake Łuknajno (Poland)? (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 277-283 
    Details
    ISSN: 1573-5117
    Keywords: phosphorus ; eutrophication ; Chara aspera ; phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Waters of Lake Łuknajno (623 ha, 3 m max. depth postglacial basin in Masurian Lakeland) are of meso-eutrophic type in spite of an intensive land impact and substantial phosphorus loading. The reason of this peculiarity is an abundance of 4 species of charophytes (Chara aculeolata, C. aspera, C. contraria and C. tomentosa) which dominate the submerged vegetation of the lake and yielded 417 g m-2 dry biomass in summer 1991. The plants have high potential for phosphorus uptake and accumulation as was checked in laboratory experiments. Due to this potential Chara can outcompete planktonic algae in mixed cultures at different mineral P supplies.
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    Phosphorus fluctuation in water and deposition into sediment within an emergent macrophyte stand (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 285-292 
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    ISSN: 1573-5117
    Keywords: phosphorus ; sediment ; lake littoral ; Equisetum fluviatile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seasonal fluctuation of phosphorus in water, and total phosphorus and different inorganic P fractions (extracted by NH4Cl, NH4F, NaOH and H2SO4) and organic P fraction (residual P) in surface sediment, were measured in the littoral of oligotrophic Lake Pääjärvi (southern Finland). After the emergence of Equisetum fluviatile L. shoots in mid June, water exchange between the littoral and pelagial area diminished and phosphorus concentrations in water and in surface sediment increased in the inner and mid littoral zones. Phosphorus pool in flocculent, ‘easily resuspensible’ sediment composed on average 62% of inorganic phosphorus and 38% of organic phosphorus. 63% of the inorganic phosphorus, on the average, was extracted from ‘apatite-P fraction’ 29% from ‘iron-P fraction’ 7% from ‘aluminum-P fraction’ and less than 1% from ‘loosely-bound P fraction’. During the growing season, net accumulation of sediment and phosphorus was measured only in the inner littoral zone whereas the outer littoral zones acted rather as a source of phosphorus for the pelagic area. The results of this study indicated that nutrient dynamics in littoral environment was through changes in flow environment greatly governed by the macrophytes.
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    URL: http://dx.doi.org/10.1007/BF00026719
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    Recent palaeolimnology of three shallow Danish lakes (1994)
    Springer
    Hydrobiologia 275-276 (1994), S. 411-422 
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    ISSN: 1573-5117
    Keywords: diatoms ; phosphorus ; weighted averaging ; lake sediments ; carbonates ; radionuclides ; mixing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Recent eutrophication histories of three shallow lakes (mean depths 〈3 m) were studied using palaeolimnological methods. Freeze-cores were dated using 210Pb, 137Cs, 134Cs and 241Am. Resultant chronologies were problematical at two sites (Væng Sø and Vesterborg Sø) due to sediment-water interface mixing, indicated by uniform 137Cs profiles over the surface 20–30 cm. Sediments at Langesø and Vesterborg Sø have a high carbonate content, which together with the high mixing rate have resulted in diatom dissolution below 30 cm at Vesterborg Sø. Diatom stratigraphy indicates relatively small biological changes at both Væng Sø and Langesø both lakes have been eutrophic for at least the last 150–200 years. Væng Sø is dominated by planktonic diatoms together with high percentages of benthic Fragilaria spp., and Langesø by planktonic diatoms, especially Cyclostephanos dubius and Stephanodiscus parvus. Epilimnetic phosphorus concentrations were inferred using weighted averaging; at Væng Sø the diatom-inferred TP (DI-TP) concentrations were close to observed values in the early 1980s, but failed to record the post-biomanipulation decrease to 55 μg l-1 after 1988, presumably due to the smoothing of the sediment record by resuspension and mixing. At Langesø two increases in DI-TP suggest a two-phase enrichment of the lake, initial eutrophication ∼ 1880, and hypertrophy after 1950. The recent DI-TP values are lower than the annual observed values, and reasons for this are discussed. Despite problems associated with sediment mixing, the sediment records of these shallow systems can still be used for monitoring and for environmental reconstructions.
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    High resolution measurements of sediment resuspension above an accumulation bottom in a stratified lake (1994)
    Springer
    Hydrobiologia 284 (1994), S. 43-57 
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    ISSN: 1573-5117
    Keywords: sediment ; resuspension ; lakes ; optical measurements ; transmissometer ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed record of suspended particulate matter (SPM) concentrations in the benthic boundary layer (BBL) 1.5 m above an accumulation bottom and 13.5 m below the surface was obtained from frequent (30 min interval) beam attenuation measurements made with a Sea Tech transmissometer in the main basin of Lake Erken, a moderately deep (mean depth 9 m, maximum depth 21 m) dimictic lake in central Sweden. Concentrations of SPM (g m−3) were not as strongly correlated to the beam attenuation coefficient (c, [m−1]), as were concentrations of the inorganic SPM fraction. Apparently, this was caused by large optically inactive organic particles which significantly affected the measurements of SPM, but had little effect on the attenuation of light. When the water column was thermally stratified, SPM concentrations in the BBL showed a seasonal increase which was related to an increase in the thermocline depth. As the epilimnion deepened, there was also a marked increase in the occurrence of rapid and large changes in SPM concentration. After the loss of stratification, the amount of SPM and the temporal variability in its concentration was reduced. Since surface waves could not influence sediment resuspension at the depth of measurement, these data show the importance of internal waves in promoting sediment resuspension in areas of sediment accumulation. The relatively short period in each summer, when the thermocline reaches a sufficient depth to allow for resuspension over accumulation bottoms, can have important consequences for both the redistribution of lake sediments and the internal loading of phosphorus.
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    Bioavailability of phosphorus in agriculturally loaded rivers in southern Finland (1994)
    Springer
    Hydrobiologia 287 (1994), S. 179-194 
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    ISSN: 1573-5117
    Keywords: agriculture ; phosphorus ; bioavailability ; bioassays ; isotherms ; eutrophication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The potential bioavailability of phosphorus in agriculturally loaded rivers of southern Finland was determined by an algal bioassay and the release of the potentially bioavailable particulate P was estimated by sorption studies. According to the bioassay 0 to 13.2 per cent (mean 5.1%) of the particulate P in river water samples was potentially bioavailable. Dissolved reactive P (DRP) in river waters appeared to be totally bioavailable whereas the dissolved unreactive P appeared not to be utilized by algae. In addition to river waters two lake sediment samples were also assayed. In these samples 0 and 2.6% of the P was bioavailable. The potential bioavailability of particulate P in agriculturally loaded rivers obtained in this study was lower than that reported in studies from other countries. The difference was assumed to arise partly from methodological factors and partly from the nature of the Finnish soils. The EPC (equilibrium phosphate concentration) values indicated that during the period when most of the agricultural loading enters the lakes in Finland, potentially bioavailable P is not released from the particles because of the relatively high DRP concentration in the receiving waters. However, during the algal production period the DRP concentration in lakes decreases below the EPC and potentially bioavailable particulate P is desorbed. The increase in pH during this period may further enhance the desorption of P.
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    Effects of homobrassinolide application on plant metabolism and grain yield under irrigated and moisture-stress conditions of two wheat varieties (1994)
    Springer
    Plant growth regulation 14 (1994), S. 173-181 
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    ISSN: 1573-5087
    Keywords: homobrassinolide ; irrigated ; membrane stability ; moisture-stress ; nitrate reductase activity ; photosynthesis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Homobrassinolide (BR) was applied either as a seed treatment or foliar spray to two contrasting wheat varieties, viz. C306 (drought tolerant) and HD2329 (drought susceptible), to examine its effects on plant metabolism and grain yield under irrigated and moisture-stress/rainfed conditions. BR application resulted in increased relative water content, nitrate reductase activity, chlorophyll content and photosynthesis under both conditions. BR application also improved membrane stability (lower injury). These beneficial effects resulted in higher leaf area, biomass production, grain yield and yield related parameters in the treated plants. All the treatments were significantly better than the untreated control. Generally, 0.05 ppm either as a seed treatment or foliar spray was more effective than the 0.01 ppm treatment. The drought-tolerant genotype C306 showed more response to BR application under moisture-stress/rainfed condition than HD 2329. Increased water uptake, membrane stability and higher carbon dioxide and nitrogen assimilation rates under stress seemed to be related to homobrassinolide-induced drought tolerance.
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    Scion-rootstock relationships with respect to height growth and foliar concentrations of nitrogen and phosphorus in reciprocal grafts of Pinus caribaea var. hondurensis (1994)
    Springer
    New forests 8 (1994), S. 71-79 
    Details
    ISSN: 1573-5095
    Keywords: foliage ; grafting ; nitrogen ; phosphorus ; Pinus caribaea ; rootstock ; scion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Both scion and rootstock clones significantly influenced scion elongation and concentrations of nitrogen and phosphorus in the scion foliage. Scion clone was the more important determinant. Scion clone × rootstock clone interactions were not significant. The ability of a clone to elongate as a scion was not correlated with its capacity to promote or retard scion elongation when used as a rootstock. Genetic differences in foliar nutrient concentrations appeared to reflect levels of nutrient demand, rather than the ability of roots to absorb nutrients. Nutrient demand of the rootstock can also explain negative correlations between nitrogen levels in rootstock clones and levels of both nitrogen and phosphorus in the scions. There was no significant relationship between scion elongation and foliar nitrogen concentrations of either rootstock or scion. The weak relationship between scion elongation and concentration of phosphorus in the rootstock apparently resulted from tissue dilution.
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    The life and work of Rosemary Lowe-McConnell: pioneer in tropical fish ecology (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 67-80 
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    ISSN: 1573-5133
    Keywords: Biography ; Behaviour ; Seasonality ; Predation ; Breeding ; Feeding ; Taxonomy ; Evolution ; Environmental fluctuations ; Tropics ; Africa ; South America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Rosemary Lowe-McConnell is one of the pioneers of tropical fish ecology. During a colourful and eventful career spanning over 45 years, she has worked in the tropical waters of Africa and South America and contributed significantly to our understanding of the ecology, zoogeography, phenology, evolution and taxonomy of tropical fishes. She has also assisted countless young ichthyologists and fisheries scientists and stimulated ichthyology through her lucid books on fish ecology. She continues to play an active role in the promotion of ichthyology and ecology from her home in Sussex in the English countryside. A brief biography and tribute is given so that her contributions to tropical fish ecology can be more widely appreciated.
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    URL: http://dx.doi.org/10.1007/BF02197835
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    Alternative life histories of the genusLucania: 3. An ecomorphological explanation of altricial (L. parva) and precocial (L. goodei) species (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 369-402 
    Details
    ISSN: 1573-5133
    Keywords: Development ; Saltatory ontogeny ; Ecomorphology ; Speciation ; Evolution ; Cleavage ; Embryo ; Larva ; Juvenile ; Cyprinodontidae ; Alprehost ; Altricial-precocial model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Important differences were observed in the early ontogenies ofLucania parva andLucania goodei. These differences can be explained in terms of the altricial-precocial model of speciation.Lucania parva can be recognized as an altricial form that produces many eggs with relatively little yolk investment, compared to the more precocialL. goodei. Many of the differences observed in embryo, larva and juvenile specimens appear to be related to these differences in gamete investment. Accelerated developmental rates in the precocial form suggest that paedomorphosis is an important proximate mechanism in the bifurcation of alternative life-history styles in this genus. Some morphological characteristics, such as vitelline circulation and body shape, may be transformations associated with the particular environmental conditions in which the animals must develop and survive. Our observations suggest that these two species in the genusLucania have followed different ontogenic trajectories in response to prevailing environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023823
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    Alternative life histories of the genusLucania: 3. An ecomorphological explanation of altricial (L. parva) and precocial (L. goodei) species (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 369-402 
    Details
    ISSN: 1573-5133
    Keywords: Development ; Saltatory ontogeny ; Ecomorphology ; Speciation ; Evolution ; Cleavage ; Embryo ; Larva ; Juvenile ; Cyprinodontidae ; Alprehost ; Altricial-precocial model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Important differences were observed in the early ontogenies ofLucania parva andLucania goodei. These differences can be explained in terms of the altricial-precocial model of speciation.Lucania parva can be recognized as an altricial form that produces many eggs with relatively little yolk investment, compared to the more precocialL. goodei. Many of the differences observed in embryo, larva and juvenile specimens appear to be related to these differences in gamete investment. Accelerated developmental rates in the precocial form suggest that paedomorphosis is an important proximate mechanism in the bifurcation of alternative life-history styles in this genus. Some morphological characteristics, such as vitelline circulation and body shape, may be transformations associated with the particular environmental conditions in which the animals must develop and survive. Our observations suggest that these two species in the genusLucania have followed different ontogenic trajectories in response to prevailing environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02197855
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  • 98
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    The life and work of Rosemary Lowe-McConnell: pioneer in tropical fish ecology (1994)
    Springer
    Environmental biology of fishes 41 (1994), S. 67-80 
    Details
    ISSN: 1573-5133
    Keywords: Biography ; Behaviour ; Seasonality ; Predation ; Breeding ; Feeding ; Taxonomy ; Evolution ; Environmental fluctuations ; Tropics ; Africa ; South America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Rosemary Lowe-McConnell is one of the pioneers of tropical fish ecology. During a colourful and eventful career spanning over 45 years, she has worked in the tropical waters of Africa and South America and contributed significantly to our understanding of the ecology, zoogeography, phenology, evolution and taxonomy of tropical fishes. She has also assisted countless young ichthyologists and fisheries scientists and stimulated ichthyology through her lucid books on fish ecology. She continues to play an active role in the promotion of ichthyology and ecology from her home in Sussex in the English countryside. A brief biography and tribute is given so that her contributions to tropical fish ecology can be more widely appreciated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023803
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  • 99
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    Assessment of nutrient availability and limitation using macroalgae (1994)
    Springer
    Journal of aquatic ecosystem stress and recovery 3 (1994), S. 27-34 
    Details
    ISSN: 1573-5141
    Keywords: nutrient limitation ; critical tissue concentrations ; nitrogen ; phosphorus ; macroalgae ; biomonitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Discs of the macroalga,Ulva lactuca L., were transplanted around an ocean outfall and at a reference site in Køge Bay, Denmark, to assess the influence of the outfall on the nutrient availability. At 2-wk intervals, samples were collected and analyzed for growth, nitrogen, and phosphorus content. The tissue concentrations of nitrogen and phosphorus decreased with distance to the outfall, showing that the tissue concentrations are suitable for monitoring nutrient availability in coastal areas and provide a time-integrated measure of the nutrient availability. The lowest tissue concentrations of nitrogen were recorded at the reference station, where the internal concentrations generally were below the critical concentration level, showing that nitrogen limited the growth. At the station located close to the outfall, the flux of nitrogen was sufficient to maintain the maximum growth rate. The tissue concentrations of phosphorus were only below the critical concentration level on one occasion, and the result showed a net uptake throughout the study period. It was concluded that in the Køge Bay, nitrogen was the main limiting factor for macroalgae growth during the summer. The applicability of tissue concentrations for assessment of nutrient availability is discussed and it is considered that the method, when evaluated against established critical concentrations, provides a valuable tool for assessing ecosystem health with regard to eutrophication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045154
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  • 100
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    Variable rates of phosphate uptake by shallow marine carbonate sediments: Mechanisms and ecological significance (1994)
    Springer
    Biogeochemistry 25 (1994), S. 127-146 
    Details
    ISSN: 1573-515X
    Keywords: carbonate sediments ; phosphate adsorption ; phosphorus ; phosphorus limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We determined phosphate uptake by calcareous sediments at two locations within a shallow lagoon in Bermuda that varied in trophic status, with one site being mesotrophic and the other being more eutrophic. Phosphate adsorption over a six hour period was significantly faster in sediments from the mesotrophic site. Uptake at both sites was significantly less than that reported for a similar experiment on calcareous sediments in an oligotrophic lagoon in the Bahamas. The difference in phosphorus adsorption between our sites did not appear to be related to sediment characteristics often cited as important, such as differences in surface area (as inferred from grain size distributions), total organic matter content, or iron content. However, the sediment total phosphorus contents were inversely related to phosphorus uptake at our sites in Bermuda, and at the previously studied Bahamas site. We hypothesize that phosphate uptake in these calcareous sediments is a multi-step process, as previously described for fluvial sediments or pure calcium carbonate solids, with rapid initial surface chemisorption followed by a slower incorporation into the carbonate solid-phase matrix. Accordingly, sediments already richer in solid phase phosphorus take up additional phosphate more slowly since the slower incorporation of surface-adsorbed phosphate into the carbonate matrix limits the rate of renewal of surface-reactive adsorption sites. Although carbonate sediments are a sink for phosphate, and thereby reduce the availability of phosphorus for benthic macrophytes and phytoplankton in the shallow overlying water, phosphate uptake by these sediments appears to decrease along a gradient from oligotrophic to eutrophic sites. If our result is general, it implies a positive feedback in phosphorus availability, with a proportionately greater percentage of phosphorus loading being biologically available longer as phosphorus loading increases. This pattern is supported by the significantly higher tissue phosphorus content of the seagrass,Thalassia testudinum, collected from the eutrophic inner bay site. Over time, this effect may tend to cause a shift from phosphorus to nitrogen limitation in some calcareous marine environments.
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    URL: http://dx.doi.org/10.1007/BF00000882
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