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  • wheat  (294)
  • Drosophila
  • GEOPHYSICS
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  • Springer  (492)
  • 1990-1994  (492)
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  • 1
    Electronic Resource
    Electronic Resource
    Unrewarding experiences and their effect on foraging in the parasitic waspLeptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 465-481 
    Details
    ISSN: 1572-8889
    Keywords: host selection ; experience ; learning ; extinction ; reinforcement ; parasitoids ; Drosophila ; Leptopilina heterotoma ; Hymenoptera ; Eucoilidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The host-foraging behavior of female entomophagous parasitoids is commonly modified by positive associative learning. Typically, a rewarding experience (e.g., successful oviposition in a host) increases a female's foraging effort in a host microhabitat of the type associated with that experience. Less well understood are the effects of unrewarding experiences (i.e., unsuccessful foraging). The influence of unrewarding experience on microhabitat choice and residence time within a microhabitat was examined for the eucoilid parasitoid,Leptopilina heterotoma, in laboratory and greenhouse assays. As determined previously, females which oviposited successfully in either of two microhabitat types (fermenting apple or decaying mushroom) strongly preferred to forage subsequently on that microhabitat type. However, failure to find hosts in the formerly rewarding microhabitat caused females to reverse their preference in favor of a novel microhabitat type. The effect, though striking, was transient: within 1–2 h, the original learned preference was nearly fully restored. Similar effects of unrewarding experiences were observed with respect to the length of time spent foraging in a microhabitat. As determined previously, oviposition experience in a particular microhabitat type increased the time spent foraging in a patch of that microhabitat type. However, failure to find hosts in the patch caused the time a wasp spent in the next unoccupied patch of that type to decrease to almost nothing. In addition, there was a tendency for an unrewarding experience on a formerly rewarding microhabitat type to extend the time spent in a patch of a novel type. The function of the observed effects of unrewarding experiences is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025444
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  • 2
    Electronic Resource
    Electronic Resource
    Drosophila do not skew offspring sex ratio as predicted by trivers and willard (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 231-239 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; sex ratio ; life history ; optimality model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on both previously published literature and results reported here, it appears thatDrosophila melanogaster meet the explicit assumptions of the Trivers and Willard offspring sex allocation model. However, contrary to the model's predictions, offspring sex ratio was not significantly affected when we manipulated factors that influence offspring quality. We suggest that contrary to implicit predictions of offspring sex ratio models,Drosophila may lack the genetic plasticity to readily alter sex ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01988907
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  • 3
    Electronic Resource
    Electronic Resource
    Egg-laying experience and acceptance of parasitized hosts by the parasitoid,Leptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 331-342 
    Details
    ISSN: 1572-8889
    Keywords: parasitoid ; superparasitism ; learning ; motivation ; egg load ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of egg-laying experience on the response of females of the eucoilid parasitoid,Leptopilina heterotoma, to parasitized and unparasitizedDrosophila melanogaster host larvae was examined under more controlled conditions than those used in past studies. In laboratory assays, we precisely manipulated both the number of eggs laid by females and the kind of larvae (parasitized versus unparasitized) in which the eggs were laid. We found that the tendency to avoid laying eggs in parasitized hosts depended markedly on whether or not eggs had been laid previously, but depended little on whether those eggs had been laid in parasitized or unparasitized hosts. The observed effect of general egg-laying experience on avoidance of parasitized hosts may reflect responses to either changes in the wasp's internal state (perhaps, changes in egg load) or changes in the wasp's neural representation of the external environment (such as those presumed to occur during learning). In light of these results, we offer a tentative reinterpretation of several earlier studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989362
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  • 4
    Electronic Resource
    Electronic Resource
    Courtship success and multivariate analysis of sexual selection on morphometric traits inDrosophila buzzatii (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 219-229 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; sexual selection gradients ; courtship success
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using wild-reared flies, we examined sexual selection on five phenotypic traits (thorax length, wing length, wing width, head width, and face width) inDrosophila buzzatii, by scoring copulatory status in nine mass mating cages. Only male face width was identified as a direct target of sexual selection in an analysis of selection gradient, while indirect selection was present on all other studied traits, as expected from their correlations with face width. In contrast to males, there was no indication of selection in females. Nor was there evidence of assortative mating. The suggested direct selection on face width seems to take place during licking behavior of the courtship and might be related to courtship feeding. This study suggests that courtship success gives rise to indirect selection on body size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01988906
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  • 5
    Electronic Resource
    Electronic Resource
    Parasitization of embedded and nonembeddedDrosophila melanogaster (Diptera: Drosophilidae) pupae by the parasitoidPachycrepoideus vindemniae (Hymenoptera: Pteromalidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 129-131 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; parasitoid wasp ; behavior ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989833
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  • 6
    Electronic Resource
    Electronic Resource
    The effects of acclimation and rearing conditions on the response of tropical and temperate populations ofDrosophila melanogaster andD. simulans to a temperature gradient (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 279-288 
    Details
    ISSN: 1572-8889
    Keywords: temperature preference ; Drosophila ; acclimation ; compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of rearing and acclimation on the response of adultDrosophila to temperature were investigated in a gradient.D. melanogaster flies preferred a higher mean temperature and were distributed over a wider range of temperatures thanD. simulans flies. Acclimating adults at different temperatures for a week did not influence the response of either species. Adults reared at 28°C as immatures had a lower mean preference than those reared at cooler temperatures, suggesting that flies compensated for the effects of rearing conditions. Adults from tropical and temperate populations ofD. melanogaster andD. simulans did not differ in the mean temperature they preferred in a gradient, suggesting little genetic divergence for this trait within species. The species differences and environmental responses may be related to changes in optimal physiological conditions for the flies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989735
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  • 7
    Electronic Resource
    Electronic Resource
    Sensorimotor transformation from light reception to phototactic behavior inDrosophila larvae (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 553-567 
    Details
    ISSN: 1572-8889
    Keywords: review ; Drosophila ; larva ; phototaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we examine theDrosophila melanogaster larval response to light. We survey the morphology of the larval visual and motor systems in relation to larval locomotory behavior and phototaxis. In addition, this paper proposes a model of sensorimotor transformation and examines the reversal in taxis occurring at theD. melanogaster larval wnadering stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025449
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  • 8
    Electronic Resource
    Electronic Resource
    DNA in wheat seeds from European archaeological sites (1994)
    Springer
    Cellular and molecular life sciences 50 (1994), S. 571-575 
    Details
    ISSN: 1420-9071
    Keywords: Ancient DNA ; archaeobotany ; carbonized grain ; DNA sequences ; glutenin alleles ; seed proteins ; Triticum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01921727
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  • 9
    Electronic Resource
    Electronic Resource
    Phylogeny of the Drosophila obscura species group deduced from mitochondrial DNA sequences (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 478-488 
    Details
    ISSN: 1432-1432
    Keywords: Mitochondrial DNA ; Nucleotide sequences ; Drosophila ; Rapid phyletic radiation ; Molecular phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Approximately 2 kb corresponding to different regions of the mtDNA of 14 different species of the obscura group of Drosophila have been sequenced. In spite of the uncertainties arising in the phylogenetic reconstruction due to a restrictive selection toward a high mtDNA A+T content, all the phylogenetic analysis carried out clearly indicate that the obscura group is formed by, at least, four well-defined lineages that would have appeared as the consequence of a rapid phyletic radiation. Two of the lineages correspond to monophyletic subgroups (i.e., afftnis and pseudoobscura), whereas the obscura subgroup remains heterogeneous assemblage that could be reasonably subdivided into at least two complexes (i.e., subobscura and obscura).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173417
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  • 10
    Electronic Resource
    Electronic Resource
    Aspects of nonrandom turnover involved in the concerted evolution of intergenic spacers within the ribosomal DNA of Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 151-159 
    Details
    ISSN: 1432-1432
    Keywords: Concerted evolution ; Molecular drive ; Drosophila ; rDNA spacers ; PCR length polymorphism ; MVR-PCR mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polymerase chain reaction (PCR)-amplified, sequenced, and digitally typed intergenic spacers (IGSs) of the ribosomal (r)DNA in D. melanogaster reveal unexpected features of the mechanisms of turnover involved with the concerted evolution of the gene family. Characterization of the structure of three isolated IGS length variants reveals breakage “hot spots” within the 330-base-pair (bp) subrepeat array found in the spacers. Internal mapping of variant repeats within the 240-bp subrepeat array using a novel digital DNA typing procedure (minisatellite variant repeat [MVR]-PCR) shows an unexpected pattern of clustering of variant repeats. Each 240-bp subrepeat array consists of essentially two halves with the repeats in each half identified by specific mutations. This bipartite structure, observed in a cloned IGS unit, in the majority of genomic DNA of laboratory and wild flies and in PCR-amplified products, has been widely homogenized yet is not predicted by a model of unequal crossing over with randomly placed recombination breakpoints. Furthermore, wild populations contain large numbers of length variants in contrast to uniformly shared length variants in laboratory stocks. High numbers of length variants coupled to the observation of a homogenized bipartite structure of the 240-bp subrepeat array suggest that the unit of turnover and homogenization is smaller than the IGS and might involve gene conversion. The use of PCR for the structural analysis of members of the rDNA gene family coupled to digital DNA typing provides powerful new inroads into the mechanisms of DNA turnover affecting the course of molecular evolution in this family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163804
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  • 11
    Electronic Resource
    Electronic Resource
    Degenerating gypsy retrotransposons in a male fertility gene on the Y chromosome of Drosophila hydei (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 452-465 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Y chromosome ; Male fertility genes ; Lampbrush loops ; Germ line ; Transposable elements ; Gypsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the evolution of the Y chromosome of Drosophila hydei, retrotransposons became incorporated into the lampbrush loop pairs formed by several of the male fertility genes on this chromosome. Although insertions of retrotransposons are involved in many spontaneous mutations, they do not affect the functions of these genes. We have sequenced gypsy elements that are expressed as constituents of male fertility gene Q in the lampbrush loop pair Nooses. We find that these gypsy elements are all truncated and specifically lost those sequences that may interfere with the continuity of lampbrush loop transcription. Only defective coding regions are found within the loop. Gypsy is not transcribed in loops of many other Drosophila species harboring the family. These results suggest that any contribution of gypsy to the function of male fertility gene Q does not depend on a conserved DNA sequence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173414
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  • 12
    Electronic Resource
    Electronic Resource
    Visual control of wing beat frequency in Drosophila (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 587-596 
    Details
    ISSN: 1432-1351
    Keywords: Wing beat frequency ; Optomotor responses ; Landing response ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present study shows that the wing beat frequency of Drosophila is visually controlled and modulated in response to different optomotor stimuli. Whereas rotational large field stimuli do not appear to modulate wing beat frequency, single rotating vertical stripes increase or decrease wing beat frequency when moving back-to-front or front-to-back, respectively. Maximal modulations occur at lateral stripe positions. Expansion stimuli eliciting the landing response cause a marked increase in wing beat frequency. Parameters of this frequency response depend in a graded fashion on certain stimulus properties, and the frequency response co-habituates with the landing response. Several results indicate that the frequency response is an integral component of the landing response, although it can also occur when the characteristic front leg extension is not observed. The complex spatial input integration underlying the frequency response and other motor components of the landing response cannot easily be explained by a system of large field integration units, but might indicate the existence of local expansion detectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199480
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  • 13
    Electronic Resource
    Electronic Resource
    Improved stability of Drosophila larval neuromuscular preparations in haemolymph-like physiological solutions (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 179-191 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Neuromuscular ; Haemolymph ; Membrane potential ; Synaptic potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neuromuscular preparations from third instar larvae of Drosophila are not well-maintained in commonly used physiological solutions: vacuoles form in the muscle fibers, and membrane potential declines. These problems may result from the Na∶K ratio and total divalent cation content of these physiological solutions being quite different from those of haemolymph. Accordingly haemolymph-like solutions, based upon ion measurements of major cations, were developed and tested. Haemolymph-like solutions maintained the membrane potential at a relatively constant level, and prolonged the physiological life of the preparations. Synaptic transmission was well-maintained in haemolymph-like solutions, but the excitatory synaptic potentials had a slower time course and summated more effectively with repetitive stimulation, than in standard Drosophila solutions. Voltage-clamp experiments suggest that these effects are linked to more pronounced activation of muscle fiber membrane conductances in standard solutions, rather than to differences in passive muscle membrane properties or changes in postsynaptic receptor channel kinetics. Calcium dependence of transmitter release was steep in both standard and haemolymph-like solutions, but higher external calcium concentrations were required for a given level of release in haemolymph-like solutions. Thus, haemolymph-like solutions allow for prolonged, stable recording of synaptic transmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215114
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  • 14
    Electronic Resource
    Electronic Resource
    Altered mechanoreceptor response in Drosophila bang-sensitive mutants (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 267-278 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Bang sensitivity ; Mechanotransduction ; Adaptation ; Sensory coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bang-sensitive mutants of Drosophila melano gaster (bas 1, bssMW1, eas2, tko25t) display seizure followed by paralysis when subjected to mechanical shock. However, no physiological or biochemical defect has been found to be common to all of these mutants. In order to observe the effects of bang-sensitive mutations upon an identified neuron, and to study the nature of mechanically induced paralysis, we examined the response of a mechanosensory neuron in these mutants. In each single mutant and the double mutant bas 1 bssMW1, the frequency of action potentials in response to a bristle displacement was reduced. This is the first demonstration of a physiological defect common to several of the bang-sensitive mutations. Adaptation of spike frequency, cumulative adaptation to repeated stimulation (fatigue) and the time course of recovery from adaptation were also examined. Recovery from adaptation to a conditioning stimulus was examined in two mutants (bas 1 and bss MW1), and initial recovery from adaptation was greater in both mutants. Quantification of receptor potentials was complicated by variability inherent in extracellular recording conditions, but examination of the waveform and range of amplitudes did not indicate clear mutant defects. Therefore the differences observed in the spike response may be due to an alteration of the transfer from receptor potentials to action potential production. DNA sequence analysis of tko and eas has indicated that they encode apparently unrelated biochemical products. Our results suggest that these biochemical lesions lead to a common physiological defect in mechanoreceptors. Although this defect does not provide a straightforward explanation for bang sensitivity, the altered cellular process may lead to bang sensitivity through its action in different parts of the nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192986
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  • 15
    Electronic Resource
    Electronic Resource
    Speciation in the Artemia genus: Mitochondrial DNA analysis of bisexual and parthenogenetic brine shrimps (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 156-168 
    Details
    ISSN: 1432-1432
    Keywords: Artemia franciscana ; Artemia salina ; Artemia parthenogenetica ; Mitochondrial DNA evolution ; Cytochrome c oxidase I ; Cytochrome b ; Drosophila ; Arthropods ; Parthenogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From the cloned mitochondrial DNAs (mtDNAs) isolated from two bisexual species, one Mediterranean, Artemia salina, and one American, Artemia franciscana, and two parthenogenetic (diploid and tetraploid) strains of Artemia parthenogenetica collected in Spain, physical maps have been constructed and compared. They are extremely different among themselves, much more than the differences between Drosophila melanogaster and D. yakuba and in the same range of different mammalian species such as mouse/rat or man/cow. The nucleotide sequences of two regions of mtDNA encoding parts of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes have been determined in the two bisexual species and the two parthenogenetic strains. Comparisons of these sequences have revealed a high degree of divergence at the nucleotide level, averaging more than 15%, in agreement with the differences found in the physical maps. The majority of the nucleotide changes are silent and there is a strong bias toward transitions, with the C↔T substitutions being highly predominant. The evolutionary distance between the two Artemia parthenogenetica is high and there is no clear relationship with any of the bisexual species, including the one present nowadays in Spain. Using a combination of molecular (mtDNA) and morphological markers it is possible to conclude that all of these Artemia isolates should be actually considered as belonging to different species, even the two Artemia parthenogenetica diploidica and tetraploidica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166162
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  • 16
    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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  • 17
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    Nucleotide sequence of the genomic region encompassing Adh and Adh-Dup genes of D. lebanonensis (Scaptodrosophila): Gene expression and evolutionary relationships (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 455-467 
    Details
    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase ; Drosophila ; Drosophila lebanonensis ; Gene expression ; Codon usage ; Phylogenetic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The region of the genome of D. lebanonensis that contains the Adh gene and the downstream Adh-dup gene was sequenced. The structure of the two genes is the same as has been described for D. melanogaster. Adh has two promoters and Adh-dup has only one putative promoter. The levels of expression of the two genes in this species are dramatically different. Hybridizing the same Northern blots with a specific probe for Adh-dup, we did not find transcripts for this gene in D. lebanonensis. The level of Adh distal transcript in adults of D. lebanonensis is five times greater than that of D. melanogaster adults. The maximum levels of proximal transcript are attained at different larval stages in the two species, being three times higher in D. melanogaster late-second-instar larvae than in D. lebanonensis first-instar larvae. The level of Adh transcripts allowed us to determine distal and proximal initiation transcription sites, the position of the first intron, the use of two polyadenylation signals, and the heterogeneity of polyadenylation sites. Temporal and spatial expression profiles of the Adh gene of D. lebanonensis show qualitative differences compared with D. melanogaster. Adh and Adh-dup evolve differently as shown by the synonymous and nonsynonymous substitution rates for the coding region of both genes when compared across two species of the melanogaster group, two of the obscura group of the subgenus Sophophora and D. lebanonensis of the victoria group of the subgenus Scaptodrsophila. Synonymous rates for Adh are approximately half those for Adh-dup, while nonsynonymous rates for Adh are generally higher than those for Adh-dup. Adh shows 76.8% identities at the protein level and 70.2% identities at the nucleotide level while Adh-dup shows 83.7% identities at the protein level and 67.5% identities at the nucleotide level. Codon usage for Adh-dup is shown to be less biased than for Adh, which could explain the higher synonymous rates and the generally lower nonsynonymous substitution rates in Adh-dup compared with Adh. Phylogenetic trees reconstructed by distance matrix and parsimony methods show that Sophophora and Scaptodrosophila subgenera diverged shortly after the separation from the Drosophila subgenus.
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    URL: http://dx.doi.org/10.1007/BF00178845
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  • 18
    Electronic Resource
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    Drive-selection equilibrium: Homopolymer evolution in the Drosophila gene mastermind (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 637-641 
    Details
    ISSN: 1432-1432
    Keywords: mastermind ; Drosophila ; Homopolymer ; Repeat length variation ; Molecular drive ; Natural selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interspecific sequence comparison of the highly repetitive Drosophila gene mastermind (mam) reveals extensive length variation in homopolymer domains. The length variation in homopolymers is due to nucleotide misalignment in the underlying triplet repeats, which can lead to slippage mutations during DNA replication or repair. In mam, the length variation in repetitive regions appears to be balanced by natural selection acting to maintain the distance between two highly conserved charge clusters. Here we report a statistical test of the null hypothesis that the similarity in the amino acid distance between the charge clusters of each species arose by chance. The results suggest that at mam there is a juxtaposition of length variability due to molecular drive and length conservation maintained by natural selection. The analysis of mam allows the extension of current theories of drive-selection interaction to encompass homopolymers. Our model of drive-selection equilibrium suggests that the physical flexibility, length variability, and abundance of homopolymer domains provide an important source of genetic variation for natural populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175884
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  • 19
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    Olfactory physiology in the Drosophila maxillary palp requires the visual system gene rdgB (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 687-693 
    Details
    ISSN: 1432-1351
    Keywords: rdgB ; Maxillary palp ; Drosophila ; Electrophysiology ; Olfaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We describe the kinetics of odorant response in the maxillary palp of Drosophila, and show that the rate of recovery from odorant stimulation is affected by mutation of the rdgB (retinal degeneration B) gene. We use immunocytochemistry to confirm that the rdgB gene product is expressed in the maxillary palp. rdgB has recently been shown to encode a protein with Ca2+-binding sites and sequence similarity to rat brain phosphatidylinositol transfer protein; it is located near the rhabdomeric membranes in photoreceptor cells, where it has been suggested to play a role in membrane transport. The delay in recovery kinetics that we observe in olfactory tissue may reflect a defect in membrane restoration at the conclusion of the olfactory transduction cascade. The use of common molecules in the physiology of two olfactory organs, and in both visual and olfactory physiology, is discussed.
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    URL: http://dx.doi.org/10.1007/BF00191841
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  • 20
    Electronic Resource
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    Quantifying relative importance of maxillary palp information on the olfactory behavior of Drosophila melanogaster (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 761-766 
    Details
    ISSN: 1432-1351
    Keywords: Olfactory behavior ; Antenna ; Maxillary palp ; Olfaction ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Maxillary palps have been proposed as secondary olfactory organs, after the antennae, in Drosophila melanogaster. Our study tries to establish the quantitative importance of both organs as olfactory information mediators. Dose-response curves for three odorants: ethyl acetate, propionaldehyde and benzaldehyde were carried out for comparing olfaction in either complete animals or flies surgically deprived of antennae. Antennaless flies tested in our behavioral assay showed indifferent, attractant and repellent responses depending on concentration, similarly as normal flies do. However, they clearly displayed less sensitivity than normal flies. The range of concentrations they were able to perceive was correlated to antennal sensitivity approximately by a factor 1∶10 for ethyl acetate and benzaldehyde, and between 1∶10 and 1∶100 at high concentrations of propionaldehyde. A complementary experiment was performed to test changes in olfactory behavior produced by removing maxillary palps in the presence of antennae. At high concentrations of odorant, responses to ethyl acetate and propionaldehyde experienced small changes when both palps were removed. Results are compatible with a summation model of all olfactory information reaching the brain either through antennae or palps.
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    URL: http://dx.doi.org/10.1007/BF00191847
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    Assessing risk associated with N fertilizer recommendations in the absence of soil tests (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 175-183 
    Details
    ISSN: 1573-0867
    Keywords: Nitrogen response ; on-farm research ; risk ; probability ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In many developing countries, fertilizer recommendations must be made in the absence of plant and soil analyses. When the region is variable in terms of soils, weather, and magnitude of response to fertilizer, a recommendation is likely to involve a high degree of risk for the farmer. Quantification of such risk is key to developing appropriate recommendations for the farmer. However, most methodologies generally used in analyzing fertilizer trials do not allow adequate quantification, especially as a continuous function, of the risk associated with a given recommendation. Three years of on-farm trials conducted in the High Valley of Mexico were used to evaluate different methodologies for generating N fertilization recommendations and their associated risk for wheat (Triticum aestivum) production in the absence of soil tests. When the traditional approach, using average yield responses or separate trial results, was used, an economic optimum was identified, but it was not possible to quantify the associated risk. In contrast, however, by using a combination of response surface methodology and simple probability analysis, the risk associated with any given recommendation was developed, even under the highly variable conditions of the study zone. The approach uses a treatment difference matrix (developed using average yield differences between a treatment and the zero N (0N) check) and its associated standard deviation over locations. From the matrix, an equation (being a function of N rate and relative grain:N price ratios) was developed that shows the probability of outperforming the 0N check for the economic optimum rate.
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    URL: http://dx.doi.org/10.1007/BF00750463
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  • 22
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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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    URL: http://dx.doi.org/10.1007/BF00750467
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  • 23
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    Wheat growth from phosphorus fertilizers as affected by time and method of application in soil with an acidic subsurface layer (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 77-82 
    Details
    ISSN: 1573-0867
    Keywords: Acidic subsurface layer ; application rate ; North Carolina phosphate rock ; placement method ; time of application ; triple superphosphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Using soils with an acidic subsurface layer, three glasshouse experiments were carried out to evaluate the effect of placement method and application rate of triple superphosphate (TSP) and North Carolina phosphate rock (NCPR) on dry matter (DM) yields. Time of application of NCPR on DM yield response of wheat was also studied. For Experiment 1, soil was collected in depth intervals of 0–2; 4–6; 6–8; and 8–10 cm from a red earth (chromic luvisol). The treatments included two P sources (TSP and NCPR), three placement methods (broadcast, banded or mixed into the subsurface layer, 6–8 cm), and six application rates. In this P deficient soil with an acidic subsurface layer, there was relatively little effect of application method of TSP on wheat yield responses. The maximum dry matter yield responses for broadcast, band and mix application methods was 30, 42 and 50 %, respectively. Responses to NCPR broadcast, band and mix methods were 20, 9 and 44 %, respectively. Mixing NCPR into to acidic subsurface layer produced yields similar to those from TSP although a higher application rate of P as NCPR was needed to achieve this outcome. Treatments for Experiments 2 and 3 were time of application of NCPR (0 and 30 days before sowing) and rate of application of NCPR (0 and 40 mg P/pot). In Experiment 2 (same soil as Experiment 1) application of NCPR prior to sowing, resulted in higher Colwell P concentration than when applied at sowing, but time of application had no effect on final DM yields. Experiment 3 used a red podzolic (chromic luvisol) soil which had a lower P-status, was more acid and had a lower exchangeable Ca2+ concentration than the red earth. Application of NCPR prior to sowing resulted in lower DM yield than when it was applied prior to sowing.
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    URL: http://dx.doi.org/10.1007/BF00750159
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    The residual effectiveness of previously applied copper fertiliser for grain yield of wheat grown on soils of south-west Australia (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 11-18 
    Details
    ISSN: 1573-0867
    Keywords: Copper fertiliser ; nitrogen fertiliser ; residual effectiveness ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The residual effectiveness of copper (Cu) applied 18 to 21 years previously was estimated for grain yield of wheat. In one field experiment, current levels of Cu fertiliser were applied and its effectiveness was compared to that of the same level of Cu applied previously. The effects of nitrogen (N) fertiliser on the Cu concentration in the youngest emerged blade and in the grain, as well as the effects of N levels on the grain yield of wheat, were also studied. Where the recommended level of Cu fertiliser had been applied previously, its residual effectiveness depended on the soil type. On the grey sands over clay and gravelly sands over clay, the residual Cu would last approximately 20 years where wheat is grown in rotation with a legume crop (Lupinus augustifolius L.) and where N fertiliser is applied at high levels (92 kg N ha−1). On the yellow brown sandy earths of the Newdegate district, the residual value was in excess of 30 years. When Cu levels in the soil are marginal, high levels of N applied to wheat crops grown on stubbles of legume crops (high soil N) could suffer from induce Cu deficiency which could reduce grain production. Critical concentrations of Cu in the youngest emerged blade of less than 1.2 mg Cu kg−1 at Gs50–59 would indicate Cu deficiency. Cu concentrations of less than 1.1–1.2 mg Cu kg−1 in the grain suggest that the wheat crop is marginally supplied with Cu. In both situations, Cu fertiliser needs to be applied before the next crop.
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    URL: http://dx.doi.org/10.1007/BF00750152
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    Penicillium bilaji and phosphorus fertilization effects on the growth, development, yield and common root rot severity of spring wheat (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 97-103 
    Details
    ISSN: 1573-0867
    Keywords: Cochliobolus sativus ; common root rot ; Penicillium bilaji ; phosphorus fertilization ; tillering ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A strain ofPenicillium bilaji Chalabuda (PB) has recently been commercially released as a seed inoculant to increase phosphorus (P) uptake by wheat (Triticum aestivum L.). The purpose of this study was to compare the effects of drill applied P (15 kg P ha−1) with PB seed inoculation on early growth, development, P uptake, and grain yield of ‘Stoa’ spring wheat at four sites in North Dakota. Fertilization with P consistently enhanced early season growth, main stem development, tillering and P uptake. Seed inoculation with PB had little or no effect on these traits. Phosphorus fertilization tended to increase common root rot severity (CRR, incited byCochliobolus sativus (Ito & Kurib) Drechs.), while PB inoculation had no effect. Grain yields were significantly increased by P fertilization at one location. Inoculation with PB also increased grain yield at this location. The reason why PB inoculation increased yield at this location is not evident, as plant growth and P uptake were not enhanced earlier in the season. Averaged across all four sites, PB inoculation increased wheat yields 66 kg ha−1, which is similar to averaged yield responses reported from the Prairie Provinces of Canada.
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    URL: http://dx.doi.org/10.1007/BF00750908
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    BrdU incorporation reveals DNA replication in non dividing glial cells in the larval abdominal CNS ofDrosophila (1994)
    Springer
    Development genes and evolution 204 (1994), S. 54-61 
    Details
    ISSN: 1432-041X
    Keywords: CNS ; Glia ; Drosophila ; BrdU
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glial cells are of significant importance for central nervous system development and function. In insects, knowledge of the types and development of CNS glia is rather low. This is especially true for postembryonic glial development. Using bromodeoxyuridine incorporation and enhancer trap lines we identified a reproducible spatial and temporal pattern of DNA replicating cells in the abdominal larval CNS (A3-7 neuromeres) ofDrosophila melanogaster. These cells correspond to embryonically established glial cells in that region. Except for a specific subfraction, these cells apparently do not divide during larval life. Similar patterns were found in two otherDrosophila species,D. virilis andD. hydei.
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    URL: http://dx.doi.org/10.1007/BF00744873
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    Drosophila glial development is regulated by genes involved in the control of neuronal cell fate (1994)
    Springer
    Development genes and evolution 204 (1994), S. 118-125 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; glia ; Proneural ; Neurogenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila proneural genes specify neuronal determination among cells within the ectoderm. Here we address the question of whether proneural genes also affect the specification of glia, the most abundant cell type in the nervous system. We provide evidence that the proneural gene daughterless is essential for the formation of two major classes of PNS glia. In contrast, the proneural genes in the achaete-scute complex have no detectable effect on the specification and differentiation of these PNS glia and certain CNS glia. We also show that, as with neuronal development, glial determination is restricted by the neurogenic genes neuralized, Delta, and the genes of the Enhancer of split complex. Finally, we demonstrate that prospero, a gene involved in neuronal differentiation, also affects glial development. These results demonstrate extensive overlap in the genetic control of glial and neuronal development.
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    URL: http://dx.doi.org/10.1007/BF00361106
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    Embryonic origin and differentiation of the Drosophila heart (1994)
    Springer
    Development genes and evolution 203 (1994), S. 266-280 
    Details
    ISSN: 1432-041X
    Keywords: Heart ; Drosophila ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have followed the normal development of the different cell types associated with the Drosophila dorsal vessel, i.e. cardioblasts, pericardial cells, alary muscles, lymph gland and ring gland, by using several tissue-specific markers and transmission electron microscopy. Precursors of pericardial cells and cardioblasts split as two longitudinal rows of cells from the lateral mesoderm of segments T2-A7 (“cardiogenic region”) during stage 12. The lymph gland and dorsal part of the ring gland (corpus allatum) originate from clusters of lateral mesodermal cells located in T3 and T1/dorsal ridge, respectively. Cardioblast precursors are strictly segmentally organized; each of T2-A6 gives rise to six cardioblasts. While moving dorsally during the stages leading up to dorsal closure, cardioblast precursors become flattened, polarized cells aligned in a regular longitudinal row. At dorsal closure, the leading edges of the cardioblast precursors meet their contralateral counterparts. The lumen of the dorsal vessel is formed when the trailing edges of the cardioblast precursors of either side bend around and contact each other. The amnioserosa invaginates during dorsal closure and is transiently attached to the cardioblasts; however, it does not contribute to the cells associated with the dorsal vessel and degenerates during late embryogenesis. We describe ultrastructural characteristics of cardioblast differentiation and discuss similarities between cardioblast development and capillary differentiation in vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00360522
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  • 29
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    Novel tissue units of regional differentiation in the gut epithelium of Drosopbila, as revealed by P-element-mediated detection of enhancer (1994)
    Springer
    Development genes and evolution 203 (1994), S. 243-249 
    Details
    ISSN: 1432-041X
    Keywords: Gut ; Drosophila ; Compartment ; Regional differentiation ; P-element enhancer detectors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analysed spatial patterns of expression of a lacZ reporter gene in the gut of Drosophila larvae that had been transformed with a P-element-lacZ vector to identify regional differences in gene expression. lacZ-positive epithelial cells formed distinct domains with discrete transverse and longitudinal boundaries along the gut tube. Boundaries were often found at sites at which morphological boundaries were not obvious. The gut epithelium was subdivided into 36 compartments by the boundaries. We refer to these novel compartments as “tissue compartments”. The lacZ-positive domain of each strain appeared as a single tissue compartment or as a combination of several tissue compartments. The tissue compartment is considered to be a unit of regional differentiation. The spatial organization of the tissue compartments may represent the “floor plan”, determined by genes that control the regional differentiation of this nonsegmental organ.
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    URL: http://dx.doi.org/10.1007/BF00360519
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    The function of the proneural genes achaete and scute in the spatio-temporal patterning of the adult labellar bristles of Drosophila melanogaster (1994)
    Springer
    Development genes and evolution 203 (1994), S. 340-350 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; achaete ; scute ; Taste bristles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sensory precursors for labellar taste bristles develop from the labial disc in three distinct temporal waves occurring at 0 h, 8 h and 14 h of pupal development. In each temporal wave, transcripts for the achaete (ac) and scute (sc) genes are expressed in overlapping patterns in cells of the disc epithelium prior to the appearance of sensory mother cells (SMCs). No bristles form in mutant flies in which the ac and sc genes are absent. When the sc gene alone is deleted, a set of seven bristles fail to form. Pulses of ubiquitous sc + expression during pupal development, in a strain mutant for both ac and sc, can result in flies with all the labellar bristles at their correct positions. sc + pulses at times corresponding to the initiation of each of the waves of SMC specification in the disc was sufficient to restore bristle pattern. Bristles were not induced at ectopic positions and times as a result of the ubiquitous expression of sc +. These results suggest that the proneural genes ac and sc do not themselves set the pattern of the labellar bristles. Instead, they are required for the elaboration of the pattern set by other gene products. We also show that the formation and positioning of the later waves of bristles can take place even in the absence of bristles normally specified earlier.
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    URL: http://dx.doi.org/10.1007/BF00457805
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    Fate-mapping in the procephalic region of the embryonic Drosopbila head (1994)
    Springer
    Development genes and evolution 203 (1994), S. 367-373 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Embryogenesis ; Morphogenetic movements ; Brain ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using intracellular horseradish peroxidase injection we traced the developmental fate of early gastrula cells of the procephalic region in the stage 16/17 embryo. Morphogenetic movements in the developing brain are described in three dimensions. The results are related to head segmentation, and an early gastrula fate map of pregnathal head segments is proposed.
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    URL: http://dx.doi.org/10.1007/BF00188684
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    BrdU incorporation reveals DNA replication in non dividing glial cells in the larval abdominal CNS of Drosophila (1994)
    Springer
    Development genes and evolution 204 (1994), S. 54-61 
    Details
    ISSN: 1432-041X
    Keywords: CNS ; Glia ; Drosophila ; BrdU
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glial cells are of significant importance for central nervous system development and function. In insects, knowledge of the types and development of CNS glia is rather low. This is especially true for postembryonic glial development. Using bromodeoxyuridine incorporation and enhancer trap lines we identified a reproducible spatial and temporal pattern of DNA replicating cells in the abdominal larval CNS (A3-7 neuromeres) of Drosophila melanogaster. These cells correspond to embryonically established glial cells in that region. Except for a specific subfraction, these cells apparently do not divide during larval life. Similar patterns were found in two other Drosophila species, D. virilis and D. hydei.
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    URL: http://dx.doi.org/10.1007/BF00189068
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    Comparison of larval and adult P-450 activity levels for alkaloid metabolism in desertDrosophila (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 1893-1906 
    Details
    ISSN: 1573-1561
    Keywords: Drosophila ; Diptera ; Drosophilidae ; cytochrome P-450 ; poly-substrate monooxygenase ; cactus ; alkaloids ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The cytochrome P-450 monooxygenase system has been implicated in plant utilization by at least three species ofDrosophila (D. nigrospiracula, D. mettleri, andD. mojavensis) that are endemic to the Sonoran Desert of the southwestern United States and northwestern Mexico. Basal and induced levels of total cytochrome P-450 were determined for third-instar and decapitated 2- to 5-day post eclosion adults of the three desert species. Total P-450 levels, both basal and induced for all species assayed, were significantly higher for adults than for larvae by up to 20-fold. On a per organism basis, the levels of in vitro metabolism of the cactus alkaloid, carnegine, and patterns of response to induction by cactus tissue for adult desertDrosophila approximated those of larvae. Induction by phenobarbital, however, resulted in levels of in vitro carnegine metabolism that were up to 5.6-fold higher in adults than in larvae.
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    URL: http://dx.doi.org/10.1007/BF02066231
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    Homologues of wheat ubiquitin-conjugating enzymes - TaUBC1 and TaUBC4 are encoded by small multigene families in Arabidopsis thaliana (1994)
    Springer
    Plant molecular biology 24 (1994), S. 651-661 
    Details
    ISSN: 1573-5028
    Keywords: protein degradation ; ubiquitin conjugating enzymes ; DNA repair ; N-end recognition ; wheat ; Arabidopsis thaliana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Covalent attachment of ubiquitin to other cellular proteins has been implicated in a multitude of diverse physiological processes in eukaryotes including selective protein degradation. This attachment is carried out by a multi-enzyme pathway consisting of three classes of enzymes: ubiquitin-activating enzymes (E1s), ubiquitin-conjugating enzymes (E2s), and ubiquitin-protein ligases (E3s). E2s accept activated ubiquitin from E1 and conjugate it to target proteins with or without the participation of specific E3s. Previously, we have isolated wheat cDNAs encoding 16 and 23 kDa E2s, TaUBC1 and TaUBC4, respectively. TaUBC1 shows structural homology to the yeast RAD6 E2 that is essential for DNA repair whereas TaUBC4 is related to the yeast ScUBC8 E2, both of which effectively conjugate ubiquitin to histones in vitro but as yet are without a known in vivo function. Here, we report the isolation of genomic and cDNA homologues of these genes from Arabidopsis thaliana. In Arabidopsis, both of these E2s are encoded by three member gene families. Members of the AtUBC1 gene family, comprising AtUBC1, 2 and 3, encode 150–152 amino acid proteins that are 83–99% identical to each other and TaUBC1 and contain four introns that are conserved with respect to position. Members of the AtUBC4 gene family, comprising AtUBC4, 5 and 6, encode 187–191 amino acid proteins that are 73–88% identical to each other and TaUBC4 and contain five introns that are conserved with respect to position. In contrast, AtUBC1-3 gene products are only 31–36% identical to those derived from AtUBC4-6. mRNA for each family was detected in Arabidopsis roots, leaves, stems, and flowers indicating that members of each family are expressed in most if not all tissues.
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    Alterations in flightin phosphorylation inDrosophila flight muscles are associated with myofibrillar defects engendered by actin and myosin heavy-chain mutant alleles (1994)
    Springer
    Biochemical genetics 32 (1994), S. 301-314 
    Details
    ISSN: 1573-4927
    Keywords: flightin ; Drosophila ; insect flight muscle ; phosphoprotein ; actin ; myosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Flightin is a 20-kD myofibrillar protein found in the stretch-activated flight muscles ofDrosophila melanogaster. Nine of the eleven isoelectric variants of flightin are generatedin vivo by multiple phosphorylations. The accumulation of these isoelectric variants is affected differently by mutations that eliminate thick filaments or thin filaments. Mutations in the myosin heavy-chain gene that prevent thick filament assembly block accumulation of all flightin variants except N1, the unphosphorylated precursor, which is present at much reduced levels. Mutations in the flight muscle-specific actin gene that block actin synthesis and prevent thin filament assembly disrupt the temporal regulation of flightin phosphorylation, resulting in premature phosphorylation and premature accumulation of flightin phosphovariants. Cellular fractionation of fibers that are devoid of thin filaments show that flightin remains associated with the thick filamentrich cytomatrix. These results suggest that flightin is a structural component of the thick filaments whose regulated phosphorylation is dependent upon the presence of thin filaments.
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    URL: http://dx.doi.org/10.1007/BF00555832
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    The amino acid sequence and reactive site of a single-headed trypsin inhibitor from wheat endosperm (1994)
    Springer
    The protein journal 13 (1994), S. 187-194 
    Details
    ISSN: 1573-4943
    Keywords: Trypsin inhibitor ; wheat ; primary structure ; reactive site ; Bowman-Birk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sequence of a trypsin inhibitor, isolated from wheat endosperm, is reported. The primary structure was obtained by automatic sequence analysis of the S-alkylated protein and of purified peptides derived from chemical cleavage by cyanogen bromide and digestion withStaphylococcus aureus V8 protease. This protein, named wheat trypsin inhibitor (WTI), which is comprised of a total of 71 amino acid residues, has 12 cysteines, all involved in disulfide bridges. The primary site of interaction (reactive site) with bovine trypsin has been identified as the dipeptide arginyl-methionyl at positions 19 and 20. WTI has a high degree of sequence identity with a number of serine proteinase inhibitors isolated from both cereal and leguminous plants. On the basis of the findings presented, this protein has been classified as a single-headed trypsin inhibitor of Bowman-Birk type.
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    Translational regulation of the heat shock response (1994)
    Springer
    Molecular biology reports 19 (1994), S. 211-220 
    Details
    ISSN: 1573-4978
    Keywords: Drosophila ; eIF-2 ; eIF-4F ; heat shock ; mRNA translation regulation ; phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract All organisms from bacteria to man respond to an exposure to higher than physiological temperatures by reprogramming their gene expression, leading to the increased synthesis of a unique set of proteins termed heat shock proteins (hsps). The hsps function as molecular chaperones in both normal and stressed cells. The rapid and efficient synthesis of hsps is achieved as a result of changes occurring at gene transcription, RNA processing and degradation, and mRNA translation. With regard to the translational regulation, the emerging picture is that the two key steps of polypeptide chain initiation, namely mRNA binding and Met-tRNA i binding to ribosomes, are regulated in heat-shocked mammalian cells. InDrosophila, mRNA binding is regulated by a structural feature of the leader of heat shock mRNAs and by the inactivation of eukaryotic initiation factor- (eIF-) 4F. No clear evidence for changes in Met-tRNA i binding has been obtained yet.
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    URL: http://dx.doi.org/10.1007/BF00986963
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    A chimeric gene (orf256) is expressed as protein only in cytoplasmic male-sterile lines of wheat (1994)
    Springer
    Plant molecular biology 26 (1994), S. 535-539 
    Details
    ISSN: 1573-5028
    Keywords: cytoplasmic male sterility ; coxI ; mitochondria ; membrane protein ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria derived from Triticum timopheevi have a chimeric gene, orf256, immediately upstream from coxI. Antibodies to a peptide corresponding to a part of the encoded amino acid sequence of orf256 detect a 7 kDa protein on western blots of mitochondrial proteins from cytoplasmic male-sterile (cms) wheat (T. aestivum nucleus, T. timopheevi mitochondria) but not in mitochondrial proteins from T. aestivum, T. timopheevi, or cms plants restored to fertility by introduction of nuclear genes for fertility restoration. The 7 kDa protein appears to serve as a marker for cms wheat. Its occurrence as an integral protein of the inner membrane may indicate a cms effect through an influence on mitochondrial membrane function.
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    URL: http://dx.doi.org/10.1007/BF00039566
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    Sharp divergence between wheat and barley at loci encoding novel members of the trypsin/α-amylase inhibitors family (1994)
    Springer
    Plant molecular biology 26 (1994), S. 1231-1236 
    Details
    ISSN: 1573-5028
    Keywords: chromosome mapping ; inhibitors of trypsin/α-amylases ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Amino acid sequences for three members (CMx1, CMx2, and CMx3) of a new subfamily of trypsin/α-amylase inhibitors in wheat have been deduced from the nucleotide sequences of the corresponding cDNAs. A cDNA clone encoding CMx1 was selected from a wheat developing endosperm library using a probe that encoded barley trypsin inhibitor BTI-CMe at low stringency. Sequences corresponding to CMx2 and CMx3 were obtained from cDNA amplified by the polymerase chain reaction. The three CMx sequences contain a premature stop codon after 363 nt, as well as a second stop codon at the same position as in BTI-CMe (nt 439–441). Southern analysis of DNAs from diploid, tetraploid, and hexaploid wheats, as well as from aneuploid lines, indicate that there is a single CMx locus in each of the three genomes of hexaploid wheat, respectively associated with chromosomal arms 4AS, 4BS, and 4DL. These genes are expressed early during endosperm development and not expressed at detectable levels in other tissues. Evolutionary implications are discussed.
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    URL: http://dx.doi.org/10.1007/BF00040705
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    A ribosomal protein S10 gene is found in the mitochondrial genome in Solanum tuberosum (1994)
    Springer
    Plant molecular biology 25 (1994), S. 743-749 
    Details
    ISSN: 1573-5028
    Keywords: apocytochrome b pseudogene ; pea cox1 ; plant mitochondria ; potato ; S10 ribosomal protein ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The S10 ribosomal protein gene (rps10), which has not been previously reported in any angiosperm mitochondrial genome, was identified by sequence analysis in the potato mitochondrial DNA. This gene is found downstream of a truncated non-functional apocytochrome b (cob) pseudogene, and is expressed as multiple transcripts ranging in size from 0.8 to 5.0 kb. Southern hybridization analysis indicates that rps10-homologous sequences are not present in the wheat mitochondrial genome. Sequence analysis of a single-copy region of the pea mitochondrial genome located upstream of cox1 [11] shows that a non-functional rps10 pseudogene is present in this species. These results suggest that the functional genes coding for wheat and pea mitochondrial RPS10 polypeptides have been translocated to the nucleus.
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    URL: http://dx.doi.org/10.1007/BF00029612
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    Triticum aestivum puroindolines, two basic cystine-rich seed proteins: cDNA sequence analysis and developmental gene expression (1994)
    Springer
    Plant molecular biology 25 (1994), S. 43-57 
    Details
    ISSN: 1573-5028
    Keywords: cDNA sequence ; cystine-rich proteins ; gene expression ; puroindolines ; tryptophan-rich domain ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From a mid-maturation seed cDNA library we have isolated cDNA clones encoding two Triticum aestivum puroindolines. Puroindoline-a and puroindoline-b, which are 55% similar, are basic, cystine-rich and tryptophan-rich proteins. Puroindolines are synthezised as preproproteins which include N- and C-terminal propeptides which could be involved in their vacuolar localization. The mature proteins have a molecular mass of 13 kDa and a calculated isoelectric point greater than 10. A notable feature of the primary structure of puroindolines is the presence of a tryptophan-rich domain which also contains basic residues. A similar tryptophan-rich domain was found within an oat seed protein and a mammalian antimicrobial peptide. The ten cysteine residues of puroindolines are organized in a cysteine skeleton which shows similarity to the cysteine skeleton of other wheat seed cystine-rich proteins. Northern blot analysis showed that puroindoline genes are specifically expressed in T. aestivum developing seeds. No puroindoline transcripts as well as no related genes were detected in Triticum durum. The identity of puroindolines to wheat starch-granule associated proteins is discussed as well as the potential role of puroindolines in the plant defence mechanism.
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    Recombinant protein expression in aDrosophila cell line: comparison with the baculovirus system (1994)
    Springer
    Cytotechnology 15 (1994), S. 139-144 
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    ISSN: 1573-0778
    Keywords: Baculovirus ; cell culture ; Drosophila ; gene expression ; insect cell ; metallothionein promoter ; recombinant protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinantDrosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by theDrosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.
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    Molecular heterogeneity of naturally occurringsn-glycerol-3-phosphate dehydrogenase low-activity variants inDrosophila melanogaster (1994)
    Springer
    Biochemical genetics 32 (1994), S. 161-179 
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    ISSN: 1573-4927
    Keywords: Drosophila ; glycerol-3-phosphate ; dehydrogenase ; low activity ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Northern analyses of two low-activitysn-glycerol-3-phosphate dehydrogenase(Gpdh) alleles extracted from natural populations ofDrosophila melanogaster showed that one of them,Gpdh ACyg22 , produced wild-type levels of a normal sized (1.7-kb) mRNA but the other,Gpdh AMB5 , had very low levels of a 1.7-kb mRNA together with low levels of a transcript 200 bp larger. The two variant genes were cloned and sequenced. Compared with normal activity alleles, there were two nucleotide differences in the DNA sequence ofGpdh ACyg22 which were in first-codon positions and would be expected to give rise to Asn-13 → Tyr and Arg-272 → Cys substitutions. The second of these changes is most likely to account for the altered properties of the enzyme. In contrast, none of the nucleotide differences inGpdh AMB5 would give rise to amino acid substitutions, but a 76-bp deletion in the 5′ region removed the normal TATA box and there was a 20-bp insertion in the same region. One of the two transcripts was derived from the use of a substitute TATA box sequence in the insertion, but the 1.9-kb transcript had heterogeneous 5′ ends that were not associated with substitute TATA box sequences. The two transcripts either are produced at a lower rate or are less stable than the normal mRNA.
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    Histone H4 acetylated at lysine 16 and proteins of theDrosophila dosage compensation pathway co-localize on the male X chromosome through mitosis (1994)
    Springer
    Chromosome research 2 (1994), S. 398-404 
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    ISSN: 1573-6849
    Keywords: dosage compensation ; Drosophila ; histone acetylation ; nuclear domains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the fruit flyDrosophila, dosage compensation involves several proteins acting in concert to double the transcriptional activity of genes on the single male X chromosome. Three of these proteins, MLE, MSL-1 and histone H4 acetylated at lysine 16 (H4Ac16), have recently been shown to be located almost exclusively on the male X chromosome in interphase (polytene) cells. We show here that in neuroblasts from third instarDrosophila larvae antisera to H4Ac16, MLE and MSL-1 uniquely label the distal, euchromatic region of the male X chromosome through mitosis. The centromere-proximal, heterochromatic region of the male X is not labelled with these antisera, nor are male autosomes or any chromosomes in female cells. That the association of H4Ac16 with the male X chromosome persists, even when the chromosome is maximally compacted and transcriptionally quiescent, argues that this modified histone is an integral component of the dosage compensation pathway. In the nuclei of interphase neuroblasts from male (but never female) larvae, antibodies to H4Ac16 revealed a small, brightly labelled patch against a background of generally weak nuclear staining. In double-labelling experiments, this patch was also labelled, albeit comparatively weakly, with antibodies to MSL-1. These results strongly suggest that the distal, euchromatic region of the X chromosome in male cells occupies a limited and relatively compact nuclear domain.
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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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    bHLH proteins encoded by theEnhancer of split complex ofDrosophila negatively interfere with transcriptional activation mediated by proneural genes (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 465-473 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Enhancer of split ; Helix-loop-helix protein ; Neurogenesis ; Transcriptional repressors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheEnhancer of split complex [E(SPL)-C] ofDrosophila participates in the control of cell fate choice by uncommitted neuroectodermal cells in the embryo. It encodes seven proteins that belong to the basic helix-loop-helix (bHLH) family, six of which are expressed in very similar patterns in the neuroectoderm. Here we describe experiments aimed at unravelling the molecular basis of their function. We found that two products of the complex, HLH-M5 andEnhancer of split, are capable of binding as homo-and heterodimers to a sequence in the promoters of theEnhancer of split andachaete genes, called the N-box, which differs slightly from the consensus binding site (the E-box) for other bHLH proteins. In transient expression assays in cell culture, both proteins were found to attenuate the transcriptional activation mediated by the proneural bHLH proteinslethal of scute anddaughterless at theEnhancer of split promoter.
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    Discrimination of related transcribed and non-transcribed repetitive DNA sequences from the Y chromosomes of Drosophila hydei and Drosophila eohydei (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 54-62 
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    ISSN: 1617-4623
    Keywords: Drosophila ; Y chromosome ; Fertility genes Lampbrush loops ; Repetitive DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The short arm of the Y chromosome of Drosophila hydei carries a single male fertility gene, gene Q, which forms the lampbrush loop pair Nooses. Conflicting observations have been reported concerning the identity of the repetitive DNA sequences that are transcribed in this loop pair. It has been claimed by other investigators that the loop transcripts contain repeats of two distinct, but related families of Y-specific repetitive DNA sequences, ayl and YsI. We reinvestigated this issue, using as probes single ayl and YsI repeats which, under stringent conditions, hybridize only to members of their own family. Under non-stringent conditions, both repeats hybridize in situ to Nooses transcripts. However, if hybridization conditions are stringent, only the ayl probe hybridizes to loop transcripts. Hybridizations to Northern blots of testis RNA confirm these results. Further, YsI repeats are not found the closely related species D. eohydei. We conclude that the YsI repeats are not relevant for the function of fertility gene Q.
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    Drosophila GABAergic systems II. Mutational analysis of chromosomal segment 64AB, a region containing the glutamic acid decarboxylase gene (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 555-564 
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    ISSN: 1617-4623
    Keywords: Drosophila ; Glutamic acid decarboxylase ; GAD ; GABA ; Lethal mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila melanogaster Gad gene maps to region 64A3-5 of chromosome 3L and encodes glutamic acid decarboxylase (GAD), the rate-limiting enzyme for the synthesis of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Because this neurotransmitter has been implicated in developmental functions, we have begun to study the role of GABA synthesis during Drosophila embryogenesis. We show that Gad mRNA is expressed in a widespread pattern within the embryonic nervous system. Similarly, GAD-immunoreactive protein is present during embryogenesis. These results prompted us to screen for embryonic lethal mutations that affect GAD activity. The chromosomal region to which Gad maps, however, has not been subjected to an extensive mutational analysis, even though it contains several genes encoding important neurobiological, developmental, or cellular functions. Therefore, we have initially generated both chromosomal rearangements and point mutations that map to the Drosophila 64AB interval. Altogether, a total of 33 rearrangements and putative point mutations were identified within region 64A3-5 to 64B12. Genetic complementation analysis suggests that this cytogenetic interval contains a minimum of 19 essential genes. Within our collection of lethal mutations are several chromosomal rearrangements, two of which are in the vicinity of the Gad locus. One of these rearrangements, Df(3L)C175, is a small deletion that removes the Gad locus and at least two essential genes; the second, T(2;3)F10, is a reciprocal translocation involving the second and third chromosomes with a break within region 64A3-5. Both of these rearrangements are associated with embryonic lethality and decreased GAD enzymatic activity.
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    Transcription of repetitive DNA sequences in the lampbrush loop pair Nooses formed by sterile alleles of fertility gene Q on the Y chromosome of Drosophila hydei (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 653-660 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Fertility genes ; Y chromosome Lampbrush loops ; Repetitive DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Y chromosomal lampbrush loop-forming male fertility genes of Drosophila consist mainly of repetitive DNA sequences that do not code for proteins. We investigated whether differences in the transcription of these sequences can be detected in male-sterile alleles of male fertility gene Q, which forms the loop pair Nooses. The loop consists, for approximately two-thirds, of repeats of the Y-specific ay1 family of repetitive DNA sequences. Of the remaining one-third, at least one-half is represented by defective retrotransposons of the gypsy family. Both sequence types are interspersed throughout the loop. Using both ay1 and gypsy sequences as probes for transcript in situ hybridization, we show that, at the level of the light microscope, transcription of neither sequence is detectably affected in the loops formed by a male-sterile allele of gene Q. We conclude that the transcription of ay1 and gypsy is required, but not sufficient for the function of gene Q.
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    The lysozyme locus in Drosophila melanogaster: an expanded gene family adapted for expression in the digestive tract (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 152-162 
    Details
    ISSN: 1617-4623
    Keywords: Antibacterial ; Digestive tract ; Drosophila ; Gene family ; Lysozyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lysozyme has been studied in insects as part of the system of inducible antibacterial defence in the haemolymph. We recently found two Drosophila lysozyme genes that are constitutively expressed in the digestive tract, and are probably involved in the digestion of bacteria in the food. To obtain an overview of the lysozyme genes in this species and their possible roles in immunity and digestion, we have now characterized all six lysozyme genes in the cloned part of the lysozyme locus at 61F, and a seventh gene that maps to the same chromosomal location. The expression of the genes follows four different patterns: firstly, four closely related genes, LysB, C, D and E, are all strongly expressed in the midgut of larvae and adults; secondly, LysP is expressed in the adult salivary gland; thirdly, LysS is expressed mainly in the gastric caecae of larvae; and finally, LysX is primarily expressed in the metamorphosing midgut of late larvae and early pupae. The LysD-like genes and LysS are strongly repressed in artificially infected animals, possibly reflecting a malaise reaction in the digestive tract. None of the genes is expressed in the fat body or haemocytes. Thus rather than being a component of the haemolymph, the Drosophila lysozymes are found mainly in the digestive tract where they are expressed at a high level. Furthermore all genes, except LysP, encode acidic proteins, in contrast to the strongly basic “typical” lysozymes. This is highly reminiscent of the situation in ruminants, where the lysozymes have been recruited for the digestion of symbiotic bacteria in the stomach.
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    Functional relationships between genes of the Shaker gene complex of Drosophila (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 197-204 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Shaker gene complex Dominant lethality ; K+ channel ; Troponin I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different mutations belonging to the HLI and HLII complementation groups of the haplolethal (HL) region of the Shaker complex (ShC) are described. The HLI complementation group includes viable (hdp), recessive lethals [l(1)1614], semidominant lethals [l(1)8384] and dominant lethals [l(1)5051,l(1)9916, l(1)13193], lack-of-function alleles that affect nervous system, cuticle and muscle development. The HLI complementation group encodes troponin I. HLII lack-of-function mutations [l(1)174 and l(l)4058] affect nervous system development. The semidominant lethal HLI mutation 1(1)8384 shows differential complementation with other mutations in the ME and HL regions of ShC. Thus, heterozygous combinations of l(1)8384 with ME mutations l(1)162 and l(1)387 are poorly viable. The same phenomenon is observed for heterozygotes of l(1)8384 with HL mutations l(1)1199, l(1)2288 and l(1)3014. These specific interactions indicate the existence of functional relationships among the genetic elements of ShC. The implications for the understanding of the functional organization of ShC are discussed.
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    Functional interactions between the gene tetanic and the Shaker gene complex of Drosophila (1994)
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    Molecular genetics and genomics 244 (1994), S. 205-215 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; tetanic ; Shaker gene complex ; Maternal effect ; K+ channel modulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different phenotypes associated with the tetanic (tta) mutation such as appendage contraction, maternal effect and low viability and fertility are enhanced by one extra dose of the Shaker gene complex (ShC). The tta mutation is lethal with two extra doses of ShC. In addition, tta embryos have a defective nervous system. In this paper, I analyse the interaction between tta and ShC to gain insight into their relationship. Aneuploid analysis suggests that the lethality is due to an interaction of the tta mutation with the maternal effect (ME) region of this gene complex. Mutations in the ME region of ShC partially suppress this interaction. Trans-heterozygous combinations of MEI[l(1)305] and MEIII [l(1)459] mutations causes dominant lethality in a tta background. Trans-heterozygous combinations of an MEII [l(1)1359] mutation with the cited MEI and MEIII mutations are lethal in a tta background. Double mutant combinations and gene dosage experiments, suggest that tta also interacts with the viable (V) region of ShC. These specific genetic interactions indicate that tta and the ME and V regions of ShC are functionally related. These results, together with the previous electrophysiological, molecular and biochemical studies on these mutants suggest an interaction at the protein level. Thus, in the case of the V region, the tta gene product may modulate the activity of the K+ channels encoded in this region. Furthermore, the extreme dosage sensitivity of the interaction between tta and ShC suggests a stoichiometric requirement for the different gene products involved, which might be physically associated and form heteromultimers.
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    URL: http://dx.doi.org/10.1007/BF00283524
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    Drosophila melanogaster acetylcholinesterase: Identification and expression of two mutations responsible for cold- and heat-sensitive phenotypes (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 699-705 
    Details
    ISSN: 1617-4623
    Keywords: Acetylcholinesterase ; Drosophila ; Thermosensitive mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ace IJ29 and Ac IJ40 are cold- and heat-sensitive variants of the gene coding for acetylcholinesterase in Drosophila melanogaster. In the homozygous condition, these mutations are lethal when animals are raised at restrictive temperatures, i.e., below 23° C for Ace IJ29 or above 25° C for Ace IJ40. The coding regions of the gene in these mutants were sequenced and mutations changing Ser374 to Phe in Ace IJ29 and Pro75 to Leu in Ace IJ40 were found. Acetylcholinesterases bearing these mutations were expressed in Xenopus oocytes and we found that these mutations decrease the secretion rate of the protein most probably by affecting its folding. This phenomenon is exacerbated at restrictive temperatures decreasing the amount of secreted acetylcholinesterase below the lethality threshold. In parallel, the substitution of the conserved Asp248 by an Asn residue completely inhibits the activity of the enzyme and its secretion, preventing the correct folding of the protein in a non-conditional manner.
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    DPhK-γ, a putative Drosophila kinase with homology to vertebrate phosphorylase kinase γ subunits: molecular characterisation of the gene and phenotypic analysis of loss of function mutants (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 588-597 
    Details
    ISSN: 1617-4623
    Keywords: Phosphorylase kinase γ gene ; Kinase ; Drosophila ; Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Partial and total loss of function mutant alleles of a putative Drosophila homologue (DPhK-γ) of the vertebrate phosphorylase kinase γ-subunit gene have been isolated. DPhK-γ is required in early embryonic processes, such as gastrulation and mesoderm formation; however, defects in these processes are seen only when both the maternal and zygotic components of DPhK-γ expression are eliminated. Loss of zygotic expression alone does not appear to affect normal embryonic and larval development; some pupal lethality is observed but the majority of mutant animals eclose as adults. Many of these adults show defects in their leg musculature (e.g. missing and degenerating muscles), in addition to exhibiting melanised “tumours” on their leg joints. Loss of only the maternal component has no obvious phenotypic consequences. The DPhKγ gene has been cloned and sequenced. It has an open reading frame (ORF) of 1680 by encoding a 560 amino acid protein. The predicted amino acid sequence of DPhK-γ has two conserved domains, the catalytic kinase and calmodulin-binding domains, separated by a linker sequence. The amino acid sequence of DPhK-γ is homologous to that of mammalian PhK-γ proteins but differs in the length and amino acid composition of its linker sequence. The expression of DPhK-γ mRNA is developmentally regulated. We discuss the implications of these observations.
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    Extractable sulphate and organic sulphur in soils and their availability to plants (1994)
    Springer
    Plant and soil 164 (1994), S. 243-250 
    Details
    ISSN: 1573-5036
    Keywords: organic sulphur ; soil testing ; sulphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ten soils collected from the major arable areas in Britain were used to assess the availability of soil sulphur (S) to spring wheat in a pot experiment. Soils were extracted with various reagents and the extractable inorganic SO4-S and total soluble S(SO4-S plus a fraction of organic S) were determined using ion chromatography (IC) or inductively-coupled plasma atomic emission spectrometry (ICP-AES), respectively. Water, 0.016 M KH2PO4, 0.01 M CaCl2 and 0.01 M Ca(H2PO4)2 extracted similar amounts of SO4-S, as measured by IC, which were consistently smaller than the total extractable S as measured by ICP-AES. The amounts of organic S extracted varied widely between different extractants, with 0.5 M NaHCO3 (pH 8.5) giving the largest amounts and 0.01 M CaCl2 the least. Organic S accounted for approximately 30–60% of total S extracted with 0.016 M KH2PO4 and the organic C:S ratios in this extract varied typically between 50 and 70. The concentrations of this S fraction decreased in all soils without added S after two months growth of spring wheat, indicating a release of organic S through mineralisation. All methods tested except 0.5 M NaHCO3-ICP-AES produced satisfactory results in the regression with plant dry matter response and S uptake in the pot experiment. In general, 0.016 M KH2PO4 appeared to be the best extractant and this extraction followed by ICP-AES determination was considered to be a good method to standardise on.
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    Biofumigation: Isothiocyanates released frombrassica roots inhibit growth of the take-all fungus (1994)
    Springer
    Plant and soil 162 (1994), S. 107-112 
    Details
    ISSN: 1573-5036
    Keywords: canola ; glucosinolates ; Indian mustard ; take-all ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The presence of root tissue of the brassicas canola and Indian mustard inhibited growth of pure cultures of the fungal pathogen which causes take-all of wheat [Gaeumannomyces graminis (Sacc.) Arx and Oliver var.tritici, abbreviated as Ggt]. Ggt growth was generally inhibited more in the presence of Indian mustard roots than canola roots. Dried irradiated roots were consistently effective in reducing Ggt growth, but growth inhibition by young live roots and macerated roots was not consistent. The inhibitory compound(s) were shown to be volatile because the symmetry of Ggt growth was not affected by the proximity of theBrassica tissue. Volatile breakdown products from maceratedBrassica roots were identified using a gas chromatograph-mass spectrometer. The major compounds found were isothiocyanates (ITCs). Canola roots released mostly methyl ITC and Indian mustard roots released mostly phenylethyl ITC. Low concentrations of these and related compounds inhibited growth of Ggt in pure culture when supplied as the vapour of pure chemicals in concentrations within the range expected during breakdown ofBrassica roots in soil.
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    3Hthymidine incorporation of rhizosphere bacteria influenced by plant N-status (1994)
    Springer
    Plant and soil 162 (1994), S. 113-116 
    Details
    ISSN: 1573-5036
    Keywords: ammonium ; nitrate ; split-roots ; root exudate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of plant-root N-status on bacterial growth in the rhizosphere was studied with 5-week-old wheat plants grown in soil with low N content obtained by mixing 9:1 gravel:sandy loam. As a consequence of N limitation, significant increase in3Hthymidine (Tdr) incorporation rate occured 3 days after addition of 30 mM ammonium compared to controls without ammonium. Plants were grown with split-roots to separate the effect of soil N from effect of plant root derived organic matter-N on bacterial activity. The increase in nitrate concentration from 10 mM to 30 mM at one part of the root system led to significant increased3HT dr incorporation in the rhizosphere at the other part of root system after 4 days showing that the composition of root exudates became more favourable for bacterial growth when plants were fertilized with the higher level of nitrate.
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    URL: http://dx.doi.org/10.1007/BF01416096
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    Growth, biomass allocation and water use efficiency of two wheat cultivars in a mediterranean environment; a pot experiment under field conditions (1994)
    Springer
    Plant and soil 162 (1994), S. 241-247 
    Details
    ISSN: 1573-5036
    Keywords: biomass allocation ; carbon isotope discrimination ; growth ; water use efficiency ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plants of two bread wheat cultivars,Triticum aestivum L. ‘Katya Al’ and ‘Mexipak 65’, were grown in pots during the crop season in the field in NW Syria, a region with a Mediterranean climate. The experiment involved two treatments. Control plants were well-watered throughout the experiment (watering to 0.22 g water g−1 dry soil). In the second treatment, water was withheld from the plants until soil water content had decreased to 0.10 g water g−1 dry soil, the level that was maintained thereafter. Water use was measured by weighing the pots, and growth by destructive sampling. Growth of Katya and Mexipak was similar. Mexipak had a lower (though not significant atp〈0.05) plant water use efficiency (WUEp) in both treatments due to higher rates of water loss. On a leaf area basis differences in water use were especially high since Mexipak had a smaller total leaf area. In spite of a smaller investment in photosynthesizing area, Mexipak achieved similar growth as Katya. Carbon isotope discrimination and organic nitrogen concentration (both higher for Mexipak) suggest that Mexipak accomplished higher mean net photosynthetic rates with a higher mean leaf diffusive conductance, higher intercellular carbon dioxide partial pressure, and possibly a greater investment in the photosynthetic apparatus compared to Katya. Differences in carbon isotope discrimination suggest a larger difference in average photosynthetic WUE (net photosynthesis/transpiration) than in plant WUE. This could indicate that loss of carbon in respiration was greater in Katya. Gas exchange measurements on the youngest fully expanded leaves showed only minor differences between the cultivars. It is hypothesized that Mexipak, with a smaller total leaf area, is able to maintain high leaf conductance and photosynthesis for a longer period of time during the day or during the life span of leaves.
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    The 2,4-D-induced wheat para-nodules are modified lateral roots with structure enhanced by rhizobial inoculation (1994)
    Springer
    Plant and soil 159 (1994), S. 121-129 
    Details
    ISSN: 1573-5036
    Keywords: 2,4-dichlorophenoxyacetate ; para-nodule ; Rhizobium trifolii ; structure ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nodular outgrowths (para-nodules or p-nodules) on the roots of wheat (Triticum aestivum L.) cv. Miskle seedlings were induced by treatment with 0.3 and 0.6mg L−1 2,4-dichlorophenoxyacetate (2,4-D). When co-inoculated with Rhizobium trifolii strain ATCC 14480, more p-nodules were formed at these levels and p-nodulation occured at 0.1 mg L−1 indicating that inoculation enhances 2,4-D-induced p-nodulation. Similar to lateral roots, the p-nodules arose from the pericycle opposite the phloem tissues and were free from the cortical cells of the parental root at all stages of development. Structurally, the p-nodules exhibited tissue differentiation. They possessed a highly organized central vascular cylinder connected to that of the parent root, an endodermis, a cap, and an apical and lateral meristems. P-nodules formed by 2,4-D treatment alone were irregularly lobed due to uncoordinated activity of the apical meristem, while those in the combined 2,4-D and inoculation treatment were more globose. The results of the present study indicate that the 2,4-D-induced wheat p-nodules are modified lateral roots, the structure of which is enhanced by rhizobial inoculation.
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    URL: http://dx.doi.org/10.1007/BF00009294
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    The completion of cell proliferation and growth in wheat radicle (1994)
    Springer
    Plant and soil 167 (1994), S. 43-49 
    Details
    ISSN: 1573-5036
    Keywords: DNA contents ; DNA synthesis ; growth ; proliferation ; radicle ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The pattern of proliferation and growth of cortical and central metaxylem cells in a radicle and the transitional zone of a wheat embryo was studied during the final stages of embryogenesis. Cell divisions finished nearer the root tip in the central metaxylem than was the case in the cortex. After divisions ceased the cells of both tissues maintained the ability to synthesize DNA and the cells began DNA endoreduplication. The maximal levels of endoreduplication were 4C and 8C in cortical and central metaxylem cells, respectively. As a result of nonsimultaneous cessation of divisions, the metaxylem cells were two or three times longer than cortical cells. The proportion of cells with the maximal DNA content was smaller in the transitional zone than in the radicle. During the final embryonal stages cell growth rate was decreased. It was established that the transition of cells to DNA synthesis was inhibited in all sites of the radicle during the completion of embryogenesis. The cell growth was topped in proximal sites of the radicle. In the division zone the cells which had already begun DNA synthesis were able to complete it and divided. Cell growth stopped simultaneously with completion of proliferation in this zone.
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    URL: http://dx.doi.org/10.1007/BF01587596
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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 
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    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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    Analysis of disease resistance and quality characters of F1 hybrids of crosses between wheat (Triticum aestivum) and spelt (Triticum spelta) (1994)
    Springer
    Euphytica 75 (1994), S. 105-110 
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    ISSN: 1573-5060
    Keywords: wheat ; spelt ; crosses ; hybrids ; quality ; disease resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary With the objective of creating new combinations of disease resistance and quality, hybrids between wheat and spelt (spelt is well adapted to cool and wet conditions) were produced and the expression of heterosis was analysed. Three winter wheat varieties were crossed reciprocally with two spelt cultivars and the F1 hybrids were tested under artificial inoculation with stripe rust, powdery mildew and leaf rust. Disease susceptibility and quality characters (protein content, Zeleny value, grain hardness) were assessed in two year field trials. For stripe rust the F1 hybrids were resistant if one of the wheat parents was resistant. Combinations with the susceptible wheat cultivar ‘Arina’ were all susceptible irrespective of using a resistant spelt partner. Although the infection with powdery mildew was rather low, a similar reaction was obtained with the susceptible wheat variety ‘Bernina’. Leaf rust revealed very specific varietal influences. The two susceptible wheat varieties ‘Bernina’ and ‘Arina’ resulted in susceptible F1 hybrids when combined with a moderately resistant spelt. Only when they were crossed with a resistant spelt cultivar the F1 hybrids were resistant. ‘Forno’, a leaf rust resistant wheat, gave resistant F1 hybrids in all combinations. Without exception the quality characters tested showed a negative heterosis effect resulting in protein levels and Zeleny values close to or below the values of the lower parent. It appears to be possible to produce resistant F1 hybrids, mostly dominated by the resistance level of the wheat partner. The quality of the hybrids is mainly suitable for biscuit and spelt specific products; it needs specific screening for combinations with acceptable breadmaking quality.
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    Seedling root response of some Kenyan bread wheat cultivars grown in acid nutrient culture solution containing aluminum (1994)
    Springer
    Plant and soil 158 (1994), S. 141-144 
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    ISSN: 1573-5036
    Keywords: acid tolerance ; cultivar differences ; root tolerance index ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine whether a series of Kenyan bread wheat cultivars differed in tolerance to aluminum toxicity. Fourteen Kenyan wheat cultivars representing current and former widely grown cultivars of diverse pedigree origin, and two control cultivars, Maringa (Al-tolerant) and Siete Cerros (Al-susceptible), were tested in solution cultures with 0 (control), 148, 593, and 2370 μM Al at pH 4.6. Highly significant (p≤0.01) differences in seedling growth were observed among cultivars for root mass, root length and root tolerance index (RTI). Significant (p≤0.05) cultivar × treatment interactions were observed for root mass and RTI. All characters were negatively affected by increased Al concentration, with root length and root mass being affected the most. RTI is a commonly used index which measures the relative performance of individual cultivars with and without aluminum stress. High levels of tolerance to Al were identified in the Kenyan cultivars by evaluating RTI with this simple nutrient solution technique. Romany and Kenya Nyumbu had RTI values approaching those of the Al tolerant Brazilian cultivar Maringa, a spring wheat standard that has been used for high Al tolerance.
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    URL: http://dx.doi.org/10.1007/BF00007927
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    Evaluation of the use of a model rhizodeposition technique to separate root and microbial respiration in soil (1994)
    Springer
    Plant and soil 165 (1994), S. 89-101 
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    ISSN: 1573-5036
    Keywords: barley ; glucose ; microbial respiration ; pulse-labelling ; rhizodeposition ; root respiration ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A model rhizodeposition technique to estimate the root and microbial components of 14C soil/root respiration in pulse-labelling experiments is described. The method involves the injection of model rhizodeposits, consisting of 14C-labelled glucose, root extract or root cell wall material, into the rooted soil of an unlabelled plant, simultaneously with the pulse-labelling of a separate but similar plant with 14CO2. In a growth chamber experiment with 30 day old wheat and barley the contribution of direct root respiration to 14C soil/root respiration over a 26 day period after labelling was estimated 89–95%. Estimates of direct root respiration in field-grown wheat and barley at different development stages in most cases accounted for at least 75% of 14C soil/root respiration over a 21 day period after labelling. The mineralization rate of injected 14C-glucose was positively correlated with the concentration of glucose-C established in soil. The use of the method in rhizosphere carbon budget estimations is evaluated.
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    URL: http://dx.doi.org/10.1007/BF00009966
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    Combined effect of salinity and hypoxia in wheat (Triticum aestivum L.) and wheat-Thinopyrum amphiploids (1994)
    Springer
    Plant and soil 166 (1994), S. 47-54 
    Details
    ISSN: 1573-5036
    Keywords: amphiploid ; hypoxia ; salinity ; Thinopyrum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of sodium chloride salinity and hypoxia were studied in eight wheat lines and three wheat-Thinopyrum amphiploids in vermiculite-gravel culture. The lines were treated with either 100 or 150 mol m−3 NaCl with and without hypoxia. Saline hypoxic conditions significantly reduced the vegetative growth, water use, grain and straw yields for all wheat varieties except the amphiploids, whereas NaCl or hypoxia alone had less pronounced effects. In addition, saline hypoxic stress reduced K+ concentration and increased significantly the Na+ and Cl− concentrations in cell sap expressed from leaves. There was more Na+ and Cl− accumulation in wheats than the amphiploids in hypoxic conditions at 150 mol m−3 NaCl. Of the wheats, Pato was the most sensitive at all stress levels while aTriticum aestivum cv. Chinese Spring ×Thinopyrum elongatum amphiploid was the most tolerant of the three amphiploids.
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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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    Redox transformations and plant uptake of selenium resulting from root-soil interactions (1994)
    Springer
    Plant and soil 158 (1994), S. 1-12 
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    ISSN: 1573-5036
    Keywords: acid soils ; ascorbic acid ; barley ; gallic acid ; manganese oxides ; oxidation-reduction ; rhizosphere ; root exudates ; selenium ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Batch studies were conducted with Mn oxides (birnessite-hausmannite mixture, BHM) and samples of four soil series from the Mid-Atlantic region of the USA to determine effects of reducing organic acids, similar to those found in the rhizosphere, on the SeO3/SeO4 distribution. Jackland (Typic Hapludalf), Myersville (Ultic Hapludalf), Christiana (Aeric Paleaquult), and Evesboro (Typic Quartizipsamment) A and B horizon soil samples with and without prior Mn oxide reduction were incubated aerobically for 10 d with 0.1 mmol kg-1 SeO3 and 0 or 25 mmol kg-1 of ascorbic acid, gallic acid, oxalic acid, or citric acid. Selenite was also added to BHM (10 mmol kg-1) with 0 or 0.1 mmol kg-1 ascorbic acid. The availability of Se for plant uptake as a result of root-soil interactions was examined using growth chamber studies with barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) seedlings grown in 150-mL cone-shaped containers to maximize root-soil surface interactions and to create ‘rhizosphere’ soil throughout the root zone. In the BHM system ascorbic acid increased oxidation of SeO3 to SeO4 to 33% of added SeO3. In the presence of ascorbic and gallic acids and Mn oxides, oxidation of SeO3 to SeO4 occurred in the B horizons of all the soils and in the A horizons of Jackland and Myersville soils. Removal of Mn oxides decreased the oxidation in some samples. Wheat and barley plants were able to accumulate up to 20 μmol Se kg-1 from the Jackland soil when soluble Se was not measurable. The root-soil interactions in the Jackland soil with barley and wheat provided the plant with Se from insoluble sources. The results also indicate that Mn oxides coming in contact with reducing root exudates have a greater ability to oxidize SeO3 to SeO4. Thus, rhizosphere processes play an important role in the availability of Se for plant uptake.
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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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    Aluminum-induced deposition of (1,3)-β-glucans (callose) inTriticum aestivum L. (1994)
    Springer
    Plant and soil 162 (1994), S. 273-280 
    Details
    ISSN: 1573-5036
    Keywords: aluminum resistance ; (1, 3)-β-glucans ; callose ; roots ; stress indicator ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Aluminum (Al)-induced damage to leaves and roots of two Al-resistant (cv. Atlas 66, experimental line PT741) and two Al-sensitive (cv. Scout 66, cv. Katepwa) lines ofTriticum aestivum L. was estimated using the deposition of (1, 3)-β-glucans (callose) as a marker for injury. Two-day-old seedlings were grown for forty hours in nutrient solutions with or without added Al, and callose deposition was quantified by spectrofluorometry (0–1000 µM Al) and localized by fluorescence microscopy (0 and 400 µM Al). Results suggested that Al caused little damage to leaves. No callose was observed in leaves with up to 400 µM Al treatment. In contrast, root callose concentration increased with Al treatment, especially in the Al-sensitive lines. At 400 µM Al, root callose concentration of Al-sensitive Scout 66 was nearly four-fold that of Al-resistant Atlas 66. After Al treatment, large callose deposits were observed in the root cap, epidermis and outer cortex of root tips of Scout 66, but not Atlas 66. The identity of callose was confirmed by a reduced fluorescence in Al-treated roots: firstly, after adding an inhibitor of callose synthesis (2-deoxy-D-glucose) to the nutrient solution, and secondly, after incubating root sections with the callosedegrading enzyme β-D-glucoside glucohydrolase [EC 3.2.1.21]. Root callose deposition may be a good marker for Al-induced injury due to its early detection by spectrofluorometry and its close association with stress perception.
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    Gravitropic response growth angle and vertical distribution of roots of wheat (Triticum aestivum L.) (1994)
    Springer
    Plant and soil 165 (1994), S. 323-326 
    Details
    ISSN: 1573-5036
    Keywords: genotype ; gravitropic response ; root depth index (RDI)_ ; root growth angle ; root vertical distribution ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Recent work on root distribution, growth angles and gravitropic responses in Japanese cultivars of winter wheat are reviewed. Vertical distribution of roots, which influences the environmental stress tolerance of plants, was observed in the 12 Japanese cultivars in the field. The root depth index (RDI: the depth at which 50% of the root length has been reached) differed among the cultivars at the stem elongation stage. Since the RDI was closely related to the growth angle of seminal roots obtained in a pot experiment, it was assumed that growth angle is useful for predicting vertical root distribution among wheat genotypes. Gravitropic responses of the primary seminal root of 133 Japanese wheat cultivars assessed by measuring the growth angle in agar medium, were larger in the northern Japanese cultivars and smaller in the southern ones. It was also found that the geographical variation resulted from the wheat breeding process, i.e. genotypes with limited gravitropic responses of roots had been selected in the southern part of Japan where excessive soil moisture is one of the most serious problems.
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    Losses of14C from roots of pulse-labelled wheat and barley during washing from soil (1994)
    Springer
    Plant and soil 166 (1994), S. 93-99 
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    ISSN: 1573-5036
    Keywords: barley ; 14C ; pulse-labelling ; roots ; washing losses ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In crop carbon budget studies losses of root material during storage and washing of samples may cause considerable errors. To correct data from field experiments where rhizosphere C fluxes in wheat and barley were determined by14C pulse-labelling at different development stages, experiments were performed to quantify losses of14C from roots during washing. Losses of14C from wheat roots grown on nutrient solution and stored in different ways, decreased from on average 45% of total14C content 8 days after labelling to 27% after 21 days. This decrease was probably related to the incorporation of14C into structural compounds. During washing of oven-dried soil cores of held-grown wheat and barley 3 weeks after labelling, different size classes of losses of14C from the roots increased substantially with the development stage of the crop at labelling. The 0.3–0.6 mm size class increased from 5% of the14C in roots 〉 0.3 mm in young plants to 25% at ripening, and the 〈 0.3 mm size class increased from 8 to 41% of total14C content. The latter size class was, however, determined by washing handpicked roots and may therefore partly consist of adhering exudates, mucilages and microorganisms. The effect of development stage on root washing losses was attributed to root senescence which increases the fragility of roots. Thus, especially at the rate development stages root washing losses caused a severe underestimation of the root14C content. However, with these results the14C distribution patterns of the field experiments could be adequately corrected.
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    Differences in the metabolic responses of root tips of wheat and rye to aluminium stress (1994)
    Springer
    Plant and soil 167 (1994), S. 165-171 
    Details
    ISSN: 1573-5036
    Keywords: aluminium tolerance ; enzymes ; root tips ; rye ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of aluminium (Al) ions on the metabolism of root apical meristems were examined in 4-day-old seedlings of two cereals which differed in their tolerance to Al: wheat cv. Grana (Al-sensitive) and rye cv. Dańkowskie Nowe (Al tolerant). During a 24 h incubation period in nutrient solutions containing 0.15 mM and 1.0 mM of Al for wheat and rye, respectively, the activity of first two enzymes in the pentose phosphate pathway (G-6-PDH and 6-PGDH) decreased in the sensitive cultivar. In the tolerant cultivar activities of these enzymes increased initially, then decreased slightly, and were at control levels after 24 h. In the Al-sensitive wheat cultivar a 50% reduction in the activity of 6-phosphogluconate dehydrogenase was observed in the presence of Al. Changes in enzyme activity were accompanied by changes in levels of G-6-P- the initial substrate in the pentose phosphate pathway. When wheat was exposed for 16 h to a nutrient solution containing aluminium, a 90% reduction in G-6-P concentration was observed. In the Al-tolerant rye cultivar, an increase and subsequently a slight decrease in G-6-P concentration was detected, and after 16 h of Al-stress the concentration of this substrate was still higher than in control plants. This dramatic Al-induced decrease in G-6-P concentration in the Al-sensitive wheat cultivar was associated with a decrease in both the concentration of glucose in the root tips as well as the activity of hexokinase, an enzyme which is responsible for phosphorylation of glucose to G-6-P. However, in the Al-tolerant rye cultivar, the activity of this enzyme remained at the level of control plants during Al-treatment, and the decrease in the concentration of glucose occurred at a much slower rate than in wheat. These results suggest that aluminium ions change cellular metabolism of both wheat and rye root tips. In the Al-sensitive wheat cultivar, irreversible disturbances induced by low doses of Al in the nutrient solution appear very quickly, whereas in the Al-tolerant rye cultivar, cellular metabolism, even under severe stress conditions, is maintained for a long time at a level which allows for root elongation to continue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01587612
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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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    Evaluation of Chinese Triticeae for resistance to Barley Yellow Dwarf Virus (BYDV) (1994)
    Springer
    Genetic resources and crop evolution 41 (1994), S. 35-41 
    Details
    ISSN: 1573-5109
    Keywords: wheat ; grass ; wide crossing ; China ; Barley Yellow Dwarf Virus (BYDV) ; luteovirus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Barley Yellow Dwarf Virus (BYDV) is recognised as a major pathological constraint to cereal production in northern China and several widespread epidemics have been reported. The host range of BYDV includes not only cereals but many grasses. The indigenous Triticeae of northern China have likely been exposed to significant disease pressure from BYDV and therefore may be a potential source of BYDV resistance for cereal improvement. A wide range of Triticeae accessions collected over three expeditions in northern China were evaluated for resistance to BYDV. Seedlings were artificially inoculated and virus levels then assayed by ELISA. Resistance and immunity to BYDV were found to be widely distributed among the seven genera of Triticeae included in the screening. A high proportion of resistant and immune accessions was found in the genera Hordeum, Leymus, Elymus and Elytrigia. The wide range of reaction types to BYDV found within many species, and even between accessions of some species, indicates that natural selection for BYDV resistance may have been relatively recent in the Chinese Triticeae. A high proportion of resistance and/or immunity was found in Xinjiang compared to the general distribution. From the Chinese Triticeae tested the Leymus species may be the most appropriate material to initiate transfer of BYDV resistance to wheat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00051421
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    DrosophilaP element: Transposition, regulation and evolution (1994)
    Springer
    Genetica 93 (1994), S. 61-78 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; transposable elements ; hybrid dysgenesis ; transcriptional regulation ; horizontal transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435240
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    Genome and stresses: Reactions against aggressions, behavior of transposable elements (1994)
    Springer
    Genetica 93 (1994), S. 149-160 
    Details
    ISSN: 1573-6857
    Keywords: environment ; genome ; stress ; transposable elements ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The action of stresses on the genome can be considered as responses of cells or organisms to external aggressions. Stress factors are of environmental origin (climatic or trophic) or of genomic nature (introduction of foreign genetic material, for example). In both cases, important perturbations can occur and modify hereditary potentialities, creating new combinations compatible with survival; such a situation may increase the variability of the genome, and allow evolutive processes to take place. The behavior of transposable elements under stress conditions is thus of particular interest, since these sequences are sources of mutations and therefore of genetic variability; they may play an important role in population adaptation. The survey of the available experimental results suggests that, although some examples of mutations and transposable elements movements induced by external factors are clearly described, environmental injuries or introduction of foreign material into a genome are not systematically followed by drastic genomic changes.
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    URL: http://dx.doi.org/10.1007/BF01435247
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    Analysis of nucleotide substitutions and amino acid conservation in theDrosophila Adh genomic region (1994)
    Springer
    Genetica 94 (1994), S. 27-36 
    Details
    ISSN: 1573-6857
    Keywords: Adh ; Adh-dup ; Drosophila ; molecular clock ; nucleotide substitution rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The homologous genomic region that contains two paralogous genes,Adh andAdh-dup, was compared in severalDrosophila species. Sequences were analyzed as follows: a) At the nucleotide level, Ka and Ks values were determined for each pair of species. Ka-Adh and Ka-Adh-dup are not significantly different. However, Ks-Adh values are significantly lower than Ks-Adh-dup, which are more variable. In agreement with other reports, lower Ks values forAdh correlate with a high level of gene expression and relatively high percentage of G+C content in the third codon position, while the opposite applies toAdh-dup. b) At the protein level, amino acid comparisons reveal conserved regions shared by ADH and ADH-DUP, which have been assigned to known functional domains. Key residues for dehydrogenasic function are also found in ADH-DUP, thus pointing to a dehydrogenase activity for ADH-DUP, albeit very different from that of ADH.
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    URL: http://dx.doi.org/10.1007/BF01429217
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    Associations of esterase 6 allozyme and activity variation with reproductive fitness inDrosophila melanogaster (1994)
    Springer
    Genetica 94 (1994), S. 43-56 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; esterase 6 ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have shown that the esterase 6 (EST6) enzyme ofD. melanogaster is mainly produced in the sperm ejaculatory duct of the adult male and comparisons of wild-type males with laboratory null mutants have suggested that the enzyme plays a role in reproductive fitness. In this study we have compared 18 field-derived lines each isoallelic forEst6 for differences in five components of male reproductive fitness. No consistent fitness differences were found among lines differing in respect of the two major allozyme classes EST6-F and EST6-S, despite other evidence that these two classes are not selectively equivalent in the field. However, differences in reproductive fitness were found among lines differing in the minor mobility variants that segregate within EST6-F and EST6-S. A failure to distinguish among these minor forms may explain the discrepancies in previous studies on the effects of the major EST6 allozymes on reproductive fitness. The most significant associations we have found between EST6 and reproductive fitness were due to variation in EST6 activity levels. Male EST6 activity levels were found to be positively correlated with their time to first mating, negatively correlated with the numbers of eggs laid and progeny produced by their mates, and negatively correlated with the frequency with which their mates remate. We conclude that some EST6 variants differ in components of male reproductive fitness operative in laboratory cultures. However, the evidence for fitness differences is stronger for variants affecting the amount, rather than the structure of the enzyme, and the direction of the differences varies between some of the fitness components tested.
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    URL: http://dx.doi.org/10.1007/BF01429219
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    Genetic, molecular and developmental analysis of the glutamine synthetase isozymes ofDrosophila melanogaster (1994)
    Springer
    Genetica 94 (1994), S. 275-281 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; glutamine synthetase ; isozyme functional specialization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The glutamine synthetase isozymes ofDrosophila melanogaster offer an attractive model for the study of the molecular genetics and evolution of a small gene family encoding enzymatic isoforms that evolved to assume a variety of specific and sometimes essential biological functions. InDrosophila melanogaster two GS. isozymes have been described which exhibit different cellular localisation and are coded by a two-member gene family. The mitochondrial GS structural gene resides at the 21B region of the second chromosome, the structural gene for the cytosolic isoform at the 10B region of the X chromosome. cDNA clones corresponding to the two genes have been isolated and sequenced. Evolutionary analysis data are in accord with the hypothesis that the twoDrosophila glutamine synthetase genes are derived from a duplication event that occurred near the time of divergence between Insecta and Vertebrata. Both isoforms catalyse all reactions catalysed by other glutamine synthetases, but the different kinetic parameters and the different cellular compartmentalisation suggest strong functional specialisation. In fact, mutations of the mitochondrial GS gene produce embryo-lethal female sterility, defining a function of the gene product essential for the early stages of embryonic development. Preliminary results show strikingly distinct spatial and temporal patterns of expression of the two isoforms at later stages of development.
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    URL: http://dx.doi.org/10.1007/BF01443441
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    Ethylene as promoter of wheat grain maturation and ear senescence (1994)
    Springer
    Plant growth regulation 15 (1994), S. 107-112 
    Details
    ISSN: 1573-5087
    Keywords: aminoethoxyvinylglycine ; ear senescence ; ethephon ; ethylene ; grain maturation ; silver thiosulfate ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This work was aimed at testing the involvement of ethylene in the maturation of grain and senescence of the foliar structures of the wheat inflorescence. Whole wheat ears emitted ethylene to the atmosphere. From pre-anthesis, ethylene emission progressively increased from 0.76 nl g−1FW h−1 to a peak 1.53 nl g−1FW h−1 at the hard dough stage of the grains, to fall to a minimum of 0.10 nl g−1FW h−1 at the dormant seed stage. Ethephon increased the ethylene release, hastened the process of grain maturation and senescence of the ears. Aminoethoxyvinylglycine and silver thiosulfate produced the opposite effects. It is concluded that ethylene plays a role in grain maturation and in the senescence of the green bracts of the inflorescence.
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    URL: http://dx.doi.org/10.1007/BF00024098
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    Gibberellins and α-amylase gene expression in germinating wheat grains (1994)
    Springer
    Plant growth regulation 15 (1994), S. 261-270 
    Details
    ISSN: 1573-5087
    Keywords: abscisic acid ; α-amylase ; germination ; gibberellin(s) ; paclobutrazol ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Gibberellins (GAs), GA8, GA17, GA19, GA20, GA29, and GA79 were identified by full-scan gas chromatography-mass spectrometry in a purified acidic fraction and GA8, GA20, GA79, and GA90 in a hydrolysed conjugate fraction from mature wheat grains. Gibberellin A20-13-O-glucoside was also quantified directly as the permethyl derivative in dry seed. The scutellum was identified as the major site of de novo GA biosynthesis by measuring ent-kaurene accumulation in vivo in grains treated with 2S,3S-paclobutrazol. Several GAs of the early 13-hydroxylation GA pathway began to accumulate in the axis and scutellum between 24 and 48 hours in untreated grains germinated at 15°C. Bioactive GA1 and GA3 also increased in the endosperm during this period, whereas abscisic acid contents of embryo and endosperm declined rapidly over 48 hours following imbibition. Treating grains with 2S,3S-paclobutrazol reduced GA1 plus GA3 content of scutella by 70–80% over 4 days without affecting significantly the steady-state pool of α-amylase mRNA transcripts. In contrast, a 50–80% reduction in the content of bioactive GAs in the endosperm was associated with a 70–78% decrease in transcripts for both α-amylase gene families in aleurones of paclobutrazol-treated grains. It was concluded that the initiation of α-amylase gene expression in wheat scutella was independent of de novo GA biosynthesis, whereas that in the aleurone was largely dependent on embryo-produced GAs.
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    URL: http://dx.doi.org/10.1007/BF00029899
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    Effectiveness of different phosphatic fertilizers measured using labelled superphosphate and phosphorus taken up by plants (1994)
    Springer
    Nutrient cycling in agroecosystems 39 (1994), S. 31-37 
    Details
    ISSN: 1573-0867
    Keywords: Compost ; diammonium phosphate ; phosphorus availability ; fertilizer effectiveness ; 32P ; rock phosphate ; superphosphate ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The agronomic effectiveness of three P fertilizers (diamonium phosphate, rock phosphate and compost) was studied in a greenhouse experiment using wheat. A radioisotopic method, using triple superphosphate labelled with32P, was used to evaluate the P in dried tops that was derived from i) the soil, ii) labelled superphosphate and iii) the fertilizer being studied. The ratio between P uptake from each fertilizer and P uptake from the soil was used to compare the effectiveness of the different fertilizers. P derived from diammonium phosphate was greater than P derived from the soil, except in one soil. P derived from rock phosphate was always lower than P derived from the soil. The effectiveness of compost depended on soil type. Compost can produce two kind of effects: i) a direct P contribution and ii) an indirect effect improving P uptake from the soil. The radioisotopic method can be used to study the effectiveness of fertilizers even when there are no differences in yield.
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    URL: http://dx.doi.org/10.1007/BF00750154
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    Large granules, nests or bands: Methods of increasing efficiency of fall-applied urea for small cereal grains in North America (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 61-87 
    Details
    ISSN: 1573-0867
    Keywords: Band placement ; barley ; cereal grains ; fall-applied N ; fertilizer efficiency ; large urea granules ; LUG ; method of placement ; nest placement ; nitrification ; time of application ; urea fertilizer ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In North America where the climate is cool enough only one crop is grown yearly, N fertilizers are sometimes applied in the previous fall rather than in the spring for fall- or spring-sown cereal grains. However, in areas where snow accumulates in winter, fall application of N fertilizers is generally inferior to spring application. Substantial nitrification takes place in winter and subsequent N loss occurs primarily in early spring by denitrification after the snow melt. Immobilization of N is also greater with fall- than spring-applied N fertilizers. Nitrogen is more efficiently retained in the soil as NH4 and thus more effectively used by plants if formation of nitrite (NO2) and NO3 is reduced or prevented by inhibiting nitrification. The nitrification is reduced when urea is placed in bands, because of high pH, ammonia concentration and osmotic pressure in the soil. The rate of nitrification is further reduced when urea is placed in widely-spaced nests (a number of urea prills placed together at a point below the soil surface) or as large urea granules (LUG) by reducing contact between the nitrifying bacteria and the NH4 released upon urea hydrolysis. A further reduction in nitrification from LUG can be obtained by addition of chemical nitrification inhibitors (such as dicyandiamide (DCD)) to LUG. The concentration of a chemical inhibitor required to suppress nitrification decreases with increasing granule size. The small soil-fertilizer interaction zone with placement of urea in nests or as LUG also reduces immobilization of fertilizer N, especially in soils amended with crop residues. The efficiency of fall-applied N is improved greatly by placing urea in nests or as LUG for small cereal grains. Yields of spring-sown barley from nests of urea or LUG applied in the fall are close to those obtained with spring-applied urea prills incorporated into the soil. Delaying urea application until close to freeze-up is also improved the efficiency of fall-applied N. This increased effectiveness of urea nests or LUG is due to slower nitrification, lower N loss over the winter by denitrification, and reduced immobilization of applied N. Fall application of LUG containing low rates of DCD slows nitrification, reduces over-winter N loss, and causes further improvement in yield and N uptake of winter wheat compared to urea as LUG alone in experiments in Ontario; in other experiments in Alberta there is no yield advantage from using a nitrification inhibitor with LUG for barley. Placement of LUG or nests of urea in soil is an agronomically sound practice for reducing N losses. This practice can eliminate or reduce the amount of nitrification inhibitor necessary to improve the efficiency of fall-applied urea where losses of mineral N are a problem. The optimum size of urea nest or LUG, and optimum combination of LUG and an efficient nitrification inhibitor need to be determined for different crops under different agroclimatic conditions. The soil (texture, CEC, N status), plant (winter or spring crop, crop geometry, crop growth duration and cultivar) and climatic (temperature, amount and distribution of precipitation) factors should be taken into account during field evaluation of LUG. There is a need to conduct region-specific basic research to understand mechanisms and magnitudes of N transformations and N losses in a given ecosystem. Prediction of nitrification from LUG or urea nests in various environments is needed. In nitrification inhibition studies with LUG and chemical nitrification inhibitors, measurements of nitrifier activity will be useful. Finally, there is need for development of applicators for mechanical placement of LUG or urea prills in widely-spaced nests in soil.
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    URL: http://dx.doi.org/10.1007/BF00750063
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    Effect of selenium-enriched calcium nitrate, top-dressed at different growth stages, on the selenium concentration in wheat (1994)
    Springer
    Nutrient cycling in agroecosystems 38 (1994), S. 199-203 
    Details
    ISSN: 1573-0867
    Keywords: calcium nitrate ; growth stages ; sodium selenate-enriched fertilizers ; Se concentration ; silty clay soil ; top-dressing ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A greenhouse experiment was conducted to evaluate the effect of Se contained in calcium nitrate, top-dressed at different growth stages, on the Se concentration in wheat (Triticum aestivum L.). Selenium as sodium selenate was added to Ca (NO3)2 and NPK (21-4-10) during the manufacturing process. A silty clay soil with soil pH of 6.1 was used. Four selenium treatments incorporated in Ca (NO3)2 were top-dressed at both the tillering and heading growth stages at rates of 0, 15, 30, and 45 mg kg−1 of Ca (NO3)2 fertilizer equivalent to about 0, 0.003, 0.007, 0.01 mg Se kg−1 soil, respectively. A fifth treatment of 20 mg Se kg−1 of NPK (21-4-10%) equivalent to 0.007 mg Se kg−1 soil was basal dressed at the time of sowing. Calcium nitrate with or without Se was top-dressed at the rate of 35 mg N kg−1. In addition all pots received a basal dose of N at the rate of 7 0 mg N kg−1 through a NPK(21-4-10) fertilizer. The Se-enriched Ca (NO3)2 increased the uptake and concentration of Se in wheat significantly (ρ〉0.05) with increasing concentration of Se in the fertilizer applied. The Se concentration in wheat grain increased from 〈1.1 to 468µg Se kg−1 in the first year when the concentration in the Se-enriched Ca (NO3)2 was increased from 0 to 45 mg Se kg−1 but the corresponding increase in the second and third year was lower. The Se concentration in the grain was more than twice of that in the straw. The uptake and concentration of Se in wheat, except in the second year, was generally higher when Se was top-dressed at heading as compared to that when it was top-dressed at tillering but the concentration differences between time of application were not statistically significant(ρ〉0.05). Basal application of Se-enriched NPK (0.007 mg Se kg−1 soil) was only half as effective as an equivalent rate of Se in top-dressed Seenriched Ca(NO3)2 in increasing the Se concentration in wheat and the concentration levels among these treatments were significantly (ρ〉0.01) different. It was concluded that topdressing of Se-enriched Ca(NO3)2 at 30 mg Se kg−1 is an effective method of application to increase the Se concentration in wheat grain to a level, 〉 100µg kg−1 dry matter, considered adequate for human consumption.
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    URL: http://dx.doi.org/10.1007/BF00749692
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    Effect of increasing distance fromAcacia nilotica trees on wheat yield (1994)
    Springer
    Agroforestry systems 25 (1994), S. 23-29 
    Details
    ISSN: 1572-9680
    Keywords: Acacia nilotica ; wheat ; border trees ; crop yield ; Pakistan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Planting trees in the cultivated fields of Pakistan is a controversial topic between foresters and agriculturists. Some farmers believe that trees significantly reduce their crop yields; therefore they avoid planting trees in their fields. On the other hand, many foresters claim trees are beneficial for crops. This study was conducted to determine the influence of boundary trees (Acacia nilotica) on the growth and yield of associated wheat crops under irrigated conditions in Punjab, Pakistan. Results indicate that close proximity to trees adversely affected tillers/m2, weight/1000 grain and the grain yield of wheat planted up to a distance of 8.5 m from the trees. Plant height and grains/spike were least affected. In general, the growth and yield of wheat improved as distance from the tree increased. Tree size did not affect wheat height, tillers/m2, grains/spike or weight/1000 grain. The grain yields were slightly lower near the largest trees (50–54.9 cm DBH trees).
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    URL: http://dx.doi.org/10.1007/BF00705704
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    Effect of induction medium pH and maltose concentration on in vitro androgenesis of hexaploid winter triticale and wheat (1994)
    Springer
    Plant cell, tissue and organ culture 39 (1994), S. 49-53 
    Details
    ISSN: 1573-5044
    Keywords: agar ; anther culture ; Ficoll ; maltose ; pH ; triticale ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Low levels of in vitro androgenesis limit the utility of anther culture as a routine tool for the improvement of triticale. The objectives of this research were to determine the effect of induction medium modifications on the embryoid induction (EI) and green plant regeneration (GPR) of three hexaploid winter triticales and a hexaploid winter wheat. Medium modifications were factorial combinations of gelling agents, pH and maltose concentration. There was a significant difference in the response of wheat and triticales. An induction medium pH of 4.8 vs. 5.8 led to higher EI percentages in all cases and in Ficoll containing medium to a significantly higher GPR in the wheat, but it had no effect on the response of the triticales. Maltose at 0.26 M vs. 0.21 M increased the EI of both the triticales and the wheat but led to higher GPR only in the case of wheat. Averaged over genotypes, induction media with agar and Ficoll 400 were superior to the liquid form. In terms of GPR the wheat gave the highest response: 9.1%. The GPR percentages for the triticales ranged from 1.4 to 7.1. Genotype specificity must be overcome if anther culture is to be routinely used in diverse arrays of triticale germplasm.
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    URL: http://dx.doi.org/10.1007/BF00037591
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    Heterosis of grain weight in wheat hybrids with Triticum timopheevi cytoplasm (1994)
    Springer
    Euphytica 75 (1994), S. 189-193 
    Details
    ISSN: 1573-5060
    Keywords: Grain filling characteristics ; heterosis ; Triticum timopheevi cytoplasm ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two kinds of wheat hybrids with the same nuclear genotype but different cytoplasms (one with T.timopheevi cytoplasm, i.e., A/R, and the other with T.aestivum cytoplasm, i.e., B/R) were produced by two 3 × 5 incomplete diallel crosses of 3 A-lines, 3 corresponding B-lines and 5 R-lines, respectively. Experimental results did not show significant differences between the hybrids of A/R and B/R in grain filling characteristics and grain weight. The beterosis of grain weight seems mainly determined by the nuclear genotype. Although the seeds set on most A-lines were shrivelled, such a phenomenon was not found in grains set on F1. The duration of the lag period (D1) and the average grain filling rates during the linear period and the mature period (i.e., FR2 and FR3) were significantly and positively related to 1000-grain weight. It was in these factors that most hybrids displayed clear mid-parent (MP) heterosis. The amount of grain weight heterosis was not significantly related to MP value. This indicates that the grain weight heterosis of wheat hybrids will not decrease with an increase of the MP value.
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    URL: http://dx.doi.org/10.1007/BF00025603
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  • 89
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    Genetics of leaf rust resistance in 13 accessions of the Watkins wheat collection (1994)
    Springer
    Euphytica 80 (1994), S. 151-155 
    Details
    ISSN: 1573-5060
    Keywords: leaf rust resistance ; Puccinia recondita ; Triticum aestivum ; wheat ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The inheritance of leaf rust resistance was studied in 13 accessions of the A.E. Watkins wheat collection. Eight of the accessions (V409, V624, V628, V712, V731, V734, V745, and V855) were shown to have gene Lr33 and four of these (V409, V624, V628, and V731) also have LrW. Accessions V624 and V338 have LrB, and V377 and V488 have Lr11. V46 has an unidentified gene that gives an intermediate level of resistance. V860 has a partially dominant gene that gives a fleck reaction to avirulent isolates in the seedling stage. This gene is different from LrW and may be previously unidentified. It has been assigned the temporary gene symbol LrW2. In addition to seedling-effective genes, V46, V731, and V745 may have Lr34 and V745 may have Lr13. The adult-plant resistance in V488, V624, and V860 could not be identified. Seedling gene LrW2 and some of the adult-plant resistance should be useful sources of resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039311
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  • 90
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    Evolution of virulence patterns in yellow rust races and its implications for Ereeding for resistance in wheat in Kenya (1994)
    Springer
    Euphytica 80 (1994), S. 165-170 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia striiformis ; yellow rust ; durable resistance ; race-specific resistance ; residual resistance ; races ; virulence, Kenya
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Virulence patterns of yellow rust isolates collected in Kenya between 1986–1989 were compared with earlier results. The number of virulence factors per race and the range in virulence factors both increased considerably. Before 1976 races carried on average 4.5 to 5.0 virulence factors, whereas the races after 1986 had a mean of 6.5 virulence factors. The range in the number of virulence factors increased from some seven to eight in the first period to 12 in the second out of the 17 evaluated. In the period 1986–1989 another three virulence factors (2, 9 and A) were assessed. All three occurred at a high frequency. Virulence neutralizing the resistance genes Yr2, Yr2+, Yr6, Yr6+, Yr7, Yr7+, Yr8, Yr9, Yr9+ and those in the cultivars Anza (A), Strubes Dickkopf (SD) and Suwon92/Omar (SU) occurred at a high frequency, while virulence for Yr3V, Yr4+, Yr5, CV and SP (resistance in Carstens V and Spaldings Prolific resp.) were not found. The remaining three virulence factors for Yr1, 10 and 3N were rare. In the past ten years the resistance of most released cultivars became ineffective in less than six years. They were shown to carry race-specific major resistance genes such as Yr7+, Yr9+, SD and A. However, in the field, the resistance of the cultivars was not completely neutralized. A residual resistance, ranging from moderate to fairly high, was observed in all cultivars in which the major gene resistances were neutralized by corresponding virulence genes. Other wheat cultivars such as Africa Mayo, Kenya Kudu, Enkoy, Kenya Leopard, Bounty, Frontatch, Bonny and Kenya Plume appeared to keep their resistance over a condiserable period of time. They are considered to be durably resistant to the Kenyan yellow rust populations. This form of resistance, together with the residual resistance, can be recommended for use in breeding programmes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00039647
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  • 91
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    Scaling CO2-photosynthesis relationships from the leaf to the canopy (1994)
    Springer
    Photosynthesis research 39 (1994), S. 321-350 
    Details
    ISSN: 1573-5079
    Keywords: big leaf ; conductance ; forest ; model ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Responses of individual leaves to short-term changes in CO2 partial pressure have been relatively well studied. Whole-plant and plant community responses to elevated CO2 are less well understood and scaling up from leaves to canopies will be complicated if feedbacks at the small scale differ from feedbacks at the large scale. Mathematical models of leaf, canopy, and ecosystem processes are important tools in the study of effects on plants and ecosystems of global environmental change, and in particular increasing atmospheric CO2, and might be used to scale from leaves to canopies. Models are also important in assessing effects of the biosphere on the atmosphere. Presently, multilayer and big leaf models of canopy photosynthesis and energy exchange exist. Big leaf models — which are advocated here as being applicable to the evaluation of impacts of ‘global change’ on the biosphere — simplify much of the underlying leaf-level physics, physiology, and biochemistry, yet can retain the important features of plant-environment interactions with respect to leaf CO2 exchange processes and are able to make useful, quantitative predictions of canopy and community responses to environmental change. The basis of some big leaf models of photosynthesis, including a new model described herein, is that photosynthetic capacity and activity are scaled vertically within a canopy (by plants themselves) to match approximately the vertical profile of PPFD. The new big leaf model combines physically based models of leaf and canopy level transport processes with a biochemically based model of CO2 assimilation. Predictions made by the model are consistent with canopy CO2 exchange measurements, although a need exists for further testing of this and other canopy physiology models with independent measurements of canopy mass and energy exchange at the time scale of 1 h or less.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00014590
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  • 92
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    Carbon translocation to the rhizosphere of maize and wheat and influence on the turnover of native soil organic matter at different soil nitrogen levels (1994)
    Springer
    Plant and soil 161 (1994), S. 233-240 
    Details
    ISSN: 1573-5036
    Keywords: C distribution ; native soil organic matter ; rhizosphere ; root released carbon ; wheat ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat and maize were grown in a growth chamber with the atmospheric CO2 continuously labelled with 14C to study the translocation of assimilated carbon to the rhizosphere. Two different N levels in soil were applied. In maize 26–34% of the net assimilated 14C was translocated below ground, while in wheat higher values (40–58%) were found. However, due to the much higher shoot production in maize the total amount of carbon translocated below ground was similar to that of wheat. At high N relatively more of the C that was translocated to the root, was released into the soil due to increased root respiration and/or root exudation and subsequent microbial utilization and respiration. The evolution rate of unlabelled CO2 from the native soil organic matter decreased after about 25 days when wheat was grown at high N as compared to low N. This negative effect of high N in soil was not observed with maize.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046394
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  • 93
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    Root length and biomass losses during sample preparation with different screen mesh sizes (1994)
    Springer
    Plant and soil 161 (1994), S. 299-303 
    Details
    ISSN: 1573-5036
    Keywords: faba bean ; root length density ; root measurement methods ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Data are presented on the differences in root length density (RLD), dry matter (DM), and root diameter values determined on wheat and faba bean using sieves of different mesh size to separate roots from soil during sample preparation. Screens with 0.2, 1, and 2 mm (0.04, 1, and 4 mm2) aperture were used. Roots collected on the 2-mm sieve represented on average 55% of the weight and only 10% of the total length collected using a 0.2-mm sieve. With a 1-mm sieve 75% of weight was retained, but only 34% of the length. In the 0–20 cm soil layer average RLD and DM values ranged between 1.3 and 2.5 cm cm-3 and 215 and 136 g m-2 for faba bean and wheat respectively with 2 mm screens and 14.6 and 18.1 cm cm-3 and 313 and 202 g m-2 with 0.2 mm sieves. RLD was more affected than weight since losses from coarse screens were largely due to fine root fractions, although the 1-and 2-mm screens retained a small amount of fine roots that were long or attached to main structures. Variability was higher for measurements on coarser screens. The use of screens much coarser than the diameter of fine roots is not recommended for the study of surface-related phenomena in which root length quantification is necessary, while it may be acceptable for gross comparisons of root weight and spatial extent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046401
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  • 94
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    Combining abilities of in vitro traits in wheat (Triticum aestivum L.) immature embryo cultures (1994)
    Springer
    Euphytica 76 (1994), S. 169-175 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; combining ability ; in vitro culture ; genotypic and phenotypic correlations ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Combining ability for six in vitro culture traits in wheat were studied in a 8×8 diallel cross (excluding reciprocals). Specific combining ability effects (sca) were significant for all six traits derived from immature embryos on two media protocols, whereas general combining ability (gca) variances were significant only for five of them. Furthermore, based on ratios obtained by comparing the ratio of K2 gca to K2 sca, sca was more important than gca for all six traits. Genetic correlations between shoot formation and other in vitro traits, except callus weight and root formation, were higher in magnitude than the corresponding phenotypic correlations estimates, indicating the importance of genetic effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022161
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  • 95
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    Gene action and heritability for photosynthetic activity in two wheat crosses (1994)
    Springer
    Euphytica 76 (1994), S. 235-238 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; photosynthesis ; gene action ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P1 and P2), F1, F2 and backcrosses (BC1 and BC2). Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022168
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  • 96
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    The derivation of compensating translocations involving homoeologous group 3 chromosomes of wheat and rye (1994)
    Springer
    Euphytica 79 (1994), S. 75-80 
    Details
    ISSN: 1573-5060
    Keywords: intergeneric gene transfer ; misdivision ; rye ; Secale cereale ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Sr27 translocation in WRT238 was found to consist of chromosome arms 3RS of rye and 3AS of common wheat. An attempt was made to purposely produce compensating translocations having 3RS and a wheat homoeologous group 3L arm. To achieve this, plants, double monosomic for 3R and a wheat homoeologous group 3 chromosome, were irradiated (7.5 Gy gamma rays) or left untreated before being used to pollinate stem rust susceptible testers. Segregation for stem rust resistance was studied to identify F2 families with Sr27-carrying translocated chromosomes, these were confirmed by means of C-banding. Compensating translocations 3RS3AL and 3RS3BL) were obtained readily and at similar frequencies from untreated and irradiated plants (respectively, 7.2% and 9.3%). Both translocation types have impaired transmission and segregate approximately 3: 2 (present: absent) in the F2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023578
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  • 97
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    Coleoptile tiller development is associated with fast early vigour in wheat (1994)
    Springer
    Euphytica 80 (1994), S. 119-124 
    Details
    ISSN: 1573-5060
    Keywords: coleoptile tiller ; Triticum aestivum ; vigour ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Faster canopy development in temperate cereals can result in more efficient utilization of wate, light and nutrients if these are in limited supply. It can also result in more competitive plants and less use of herbicides. The possible importance of the coleoptile tiller for increasing early vigour in wheat (Triticum aestivum L.) was determined for twelve F4 lines in two experiments. Each F4 line was chosen for variation in the presence and absence of a coleoptile tiller in plants in the previous generation; each F4 line was traced to a single F2 plant from a multiple convergent cross of sixteen parents. Eight plants of each of the F4 lines were grown in a single row in both experiments. Just after the coleoptile tiller appeared, plants within each line were classified into one of two groups; one group contained plants with large coleoptile tillers whereas the other group had either small coleoptile tillers or none at all. Leaf expansion rates were determined non-destructively at regular intervals, and plants were harvested to determine leaf and tiller characteristics when there were about five mainstem leaves. There was substantial variation in the leaf area of the coleoptile tiller both between groups and among lines. In both experiments plants with a large coleoptile tiller had 24–30% more leaf area and dry weight than plants selected with a small or absent coleoptile tiller up to the final harvest. Leaf expansion rates (increase in leaf area per day) were 25 to 35% greater in the large coleoptile tiller selections from the time tillers first appeared to the time of harvest, whereas the relative leaf expansion rate (increase in leaf area per unit of leaf area present per day) of the large selections was significantly greater than the small selections only at the time of appearance of the coleoptile tiller and just after. There was no evidence that the early appearance of a coleoptile tiller was associated with the largest seedlings or that it inhibited the growth of later tillers. It is concluded that selection for the appearance of a large coleoptile tiller should improve the early vigour of temperate cereals.
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    URL: http://dx.doi.org/10.1007/BF00039306
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  • 98
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    Growth retardant activity of paclobutrazol enantiomers in wheat seedlings (1994)
    Springer
    Plant growth regulation 15 (1994), S. 281-291 
    Details
    ISSN: 1573-5087
    Keywords: abscisic acid ; enantiomers ; gibberellin ; paclobutrazol ; sterols ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The resolved enantiomers of paclobutrazol appeared to have different primary modes of action as plant growth retardants in rht3 (tall) wheat seedlings. 2S,3S-Paclobutrazol reduced shoot growth more effectively than root growth, whereas the opposite was the case with the 2R,3R-enantiomer. Low concentrations (0.03–1.0 μM) of 2S,3S-paclobutrazol specifically inhibited gibberellin A1 (GA1) production in Rht3 (dwarf) seedlings without affecting shoot growth, confirming that inhibition of GA biosynthesis is the primary mode of action of this enantiomer. Reductions in shoot growth of rht3 (tall) wheat treated with 2S,3S-paclobutrazol were associated with reductions in GA1 content, an effect that could be reversed by gibberellic acid (GA3) application, showing that GAs are important regulators of light-grown shoot growth in wheat. The inhibition of root growth of wheat seedlings following treatment with 2R,3R-paclobutrazol was associated with a decline in de novo synthesis of major sterols, a decrease in stigmasterol: sitosterol ratio and an accumulation of the 14α-methyl sterol, obtusifoliol. Concentrations 〉3 μM 2S,3S-paclobutrazol also affected de novo sterol production in wheat roots, suggesting that root growth is more responsive to interference with sterol than GA biosynthesis. There was a decline in abscisic acid (ABA) content in Rht3 (dwarf) shoots treated with relatively high concentrations of 2S,3S-paclobutrazol but no effect with its optical isomer.
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    URL: http://dx.doi.org/10.1007/BF00029901
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  • 99
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    The homoeologous relationships of the arms of wheat chromosomes 2A and 2D to chromosome 2B and their effect on homoeologous pairing (1994)
    Springer
    Chromosome research 2 (1994), S. 275-279 
    Details
    ISSN: 1573-6849
    Keywords: C-banding ; homoeologous pairing ; homoeologous relationships ; pairing genes ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Homoeologous relationships between the arms of wheat group 2 chromosomes were analysed by studying homoeologous pairing in wheat—rye hybrids. Chromosomes 2A and 2D were identified using telocentrics 2AS, 2DS or 2DL. The remaining wheat chromosomes and their arms were identified by C-banding. Wheat chromosomes in the hybrids were derived from plants which were heterozygous(Ph1/ph1b) and monotelocentric for 2AS, 2DS or 2DL. In these plants, chromosome 2B and the telocentric showed regular bivalent pairing. From the results of homoeologous pairing in wheat—rye hybrids, normal homoeologous relationships between 2AS, 2BS and 2DS, as well as between 2AL, 2BL and 2DL, were deduced. There was no evidence that wheat group 2 chromosomes were involved in evolutionary chromosome rearrangements. The existence of a pairing promoter gene on chromosome arm 2DS was supported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01552721
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  • 100
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    Introgression ofElymus trachycaulus chromatin into common wheat (1994)
    Springer
    Chromosome research 2 (1994), S. 3-13 
    Details
    ISSN: 1573-6849
    Keywords: Elymus trachycaulus ; introgression ; molecular cytogenetics ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A number of wheat—Elymus trachycaulus (2n= 4x= 28, genomically StStHtHt) chromosome addition, substitution, and translocation lines were isolated from the derivatives of anE. trachycaulus × wheat hybrid. Eighteen out of a total of 28 chromosome arms ofE. trachycaulus were recovered in the addition lines. The genomic affinity of individualE. trachycaulus chromosomes was analysed by comparative chromosome banding andin situ hybridization using genome-specific repetitive DNA sequences as probes. The homoeology of theE. trachycaulus chromosomes added to wheat was determined by storage protein, isozyme, and restriction fragment length polymorphism analysis. Alloplasmic wheat—E. trachycaulus chromosome additions were isolated which only involved chromosome 1Ht and 1St that carry fertility restoration geneRf-H t1 andRf-S t1, respectively. Based on the results of production and characterization of a wheat—E. trachycaulus 5Ht(5B) substitution line, it is likely that some wheat chromosomes can be well compensated genetically byE. trachycaulus chromosomes. Several spontaneous wheat—E. trachycaulus chromosome translocation lines were detected. All the translocation lines involved either 1Ht or 1St. To estimate the potential of recombination between wheat andE. trachycaulus chromosomes, a backcross population derived from a plant which was double monosomic for chromosomes 7A and 7AL·7AS—1StS and aph1b gene was developed. The plants from this population were analysed for 1St-specific genetic markers and no recombinant was recovered.
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    URL: http://dx.doi.org/10.1007/BF01539447
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