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  • Yeast  (41)
  • taxonomy  (37)
  • Springer  (78)
  • American Meteorological Society
  • Periodicals Archive Online (PAO)
  • 1995-1999
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  • 1940-1944
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  • 1941
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  • Springer  (78)
  • American Meteorological Society
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  • 1990-1994  (78)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 191-195 
    ISSN: 1476-5535
    Keywords: Yeast ; Trehalose ; Osmotolerance ; Viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A total of 12 yeast strains from various genera were examined for their ability to produce ethanol in the presence of high concentrations of glucose. From these studies, the yeastsTorulaspora delbrueckii andZygosaccharomyces rouxii were observed to the most osmotolerant. These osmotolerant yeast strains were also observed to possess high concentrations of intracellular trehalose. Futhermore, these strains were found to be tolerant to long-term storage at −20°C and to storage at 4°C in beer containing 5% (v/v) ethanol. Cells containing high trehalose levels at the time of freezing or cold storage exhibited the highest cell viabilities. Trehalose concentration was observed to increase during growth on glucose, reaching a maximum after 24–48 h. Increasing the incubation temperature from 21 to 40°C also resulted in an increase in intracellular trehalose content. These results suggest that trehalose plays a role in enhancing yeast survival under environmentally stressful conditions.
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  • 2
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 263-268 
    ISSN: 1476-5535
    Keywords: Yeast ; β-Glucanase ; β-Glucosidase catabolite repression ; Sporulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The activities of three glycosidases, β-glucosidase and β(1,3)- and β(1,6)-glucanases have been monitored during growth and blastospore formation inSaccharomycopsis fibuligera. The assays were carried out on the cell-free culture and in a cell-free extract and a wall autolysate preparation from the growing cells. In complex medium containing 1% glucose an increase in the level of all three enzymes was associated with the transition from mycelium to blastospores. When the level of glucose was increased to 5% blastospore formation was repressed and the level of β-glucanases only increased at the end of the fermentation. The β-glucosidase activity increased during the growth phase. In a defined medium in which slow growth in a wholly yeast-like form was observed, growth was not associated with a high level of β-glucanase activity.
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  • 3
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 35-39 
    ISSN: 1476-5535
    Keywords: 2-Deoxy-d-glucose ; Yeast ; Catabolite repression ; Derepression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The non-metabolizable and toxic glucose analogue 2-deoxy-d-glucose (2-DOG) has been widely employed to screen for regulatory mutants which lack catabolite repression. A number of yeast mutants resistant to 2-DOG have recently been isolated in this laboratory. One such mutant, derived from aSaccharomyces cerevisiae haploid strain, was demonstrated to be derepressed for maltose, galactose and sucrose uptake. Furthermore, kinetic analysis of glucose transport suggested that the high affinity glucose transport system was also derepressed in the mutant strain. In addition, the mutant had an increased intracellular concentration of trehalose relative to the parental strain. These results indicate that the 2-DOG resistant mutant is defective in general glucose repression.
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  • 4
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    Current genetics 19 (1991), S. 329-332 
    ISSN: 1432-0983
    Keywords: Mismatch repair ; Plasmid integration ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A single base pair mismatch (G:T or A:C) in the CYC1 gene of the integrative plasmid pAB218 stimulates up to a five-fold integration into the yeast chromosome. Analysis of chromosomal sites of plasmid integration suggests that the mismatch-stimulated integration is not targeted as would be expected if crossovers, localised in the region of the mismatch, were a necessary step in mismatch repair. Instead, the observed mismatch-stimulated plasmid integration could be due to potentially recombinogenic structures formed during mismatch repair, such as single-stranded gaps or denatured DNA regions extending around the plasmid molecule.
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  • 5
    ISSN: 1432-0983
    Keywords: PET genes ; Yeast ; Mitochondria ; ATP synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study details the characteristics of two temperature-conditional pet mutants of yeast, strains ts1860 and ts379, which at the non-permissive temperature show deficiencies in the formation of three mitochondrially encoded subunits of the ATP synthase complex. By analysis of mitochondrial translation products, and of mitochondrial transcription in temperature shift experiments from the permissive (22°C) to the non-permissive (36°C) temperature, it was concluded that the nuclear mutations in both mutants primarily inhibit synthesis of ATP synthase subunit 9, and that reductions in subunit 8 and 6 synthesis are secondary pleiotropic effects. Following transfer to 36°C, cells of mutant ts379 display a near complete inhibition of subunit 9 synthesis within 1 h, coincident with a marked reduction in the level of the cognate oli1 mRNA. On the other hand, near complete inhibition of subunit 9 synthesis in strain ts1860 occurs after 3 h at 36°C, at which time there is little change in the level of subunit 9 mRNA. In both mutants the mRNA levels for subunits 6 and 8 are not significantly affected at the time of inhibition of subunit 9 synthesis. Provision of an alternative source of subunit 8, translated extra-mitochondrially for import into the organelle, does not overcome the mutant phenotype of either mutant at 36°C, confirming that subunit 8 is not the sole or primary deficiency in each mutant. The mutants indicate that the products of a least two nuclear genes (designated AEP1 and AEP2) are required for the expression of the mitochondrial oli1 gene and the synthesis of subunit 9. The product of the AEP1 gene (defective in mutant ts1860) is required for translation of oli1 mRNA while the AEP2 product (defective in mutant ts379) is essential either for the stability of oli1 mRNA or for the correct processing of precursor transcripts to the mature message.
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  • 6
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    Current genetics 19 (1991), S. 389-393 
    ISSN: 1432-0983
    Keywords: Yeast ; Pichia inositovora ; Linear plasmids ; Killer toxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pichia inositovora, strain NRRL Y-18709, which contains three linear double-stranded DNA plasmids, pPinl-1, pPinl-2 and pPinl-3, was cured of these plasmids both by growing the strain in the presence of 50 μg/ml bisbenzimide, and by exposure to ultraviolet light. Both cured and uncured strains were tested for growth on a variety of carbon sources. No differences in growth response were detected, indicating no discernible involvement of the linear plasmids in the catabolism of these compounds. Culture supernatants of Pichia inositovora were shown to contain a substance larger than 100 kDa that is toxic to Saccharomyces cerevisiae, strain GS 1688. Toxin activity was optimal in YEPD assay plates containing 50 mM citrate buffer with a pH between 3.4 and 4.2. Culture supernatants from P. inositovora were also weakly active against Cephaloascus albidus, strain NRRL Y-18710, and Citeromyces matritensis, strain NRRL Y-18711. Concentrated supernatants from cured P. inositovora strains did not exhibit these activities, consistent with the hypothesis that this toxic activity is linear plasmid-encoded. Unlike the wellknown Kluyveromyces lactis system or the newly identified P. acaciae system, P. inositovora strains cured of their linear plasmids do not become detectably sensitive to toxin produced by the wild-type strain, suggesting a nonplasmid-encoded immunity function.
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  • 7
    ISSN: 1432-0983
    Keywords: Yeast ; Molecular cloning ; Nitrogen mustard hyper-resistance ; Choline transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The recessive hnm1 mutant allele is responsible for hyper-resistance to nitrogen mustard in Saccharomyces cerevisiae. Transformation with a single-copy HNM1 wild-type allele of such hyper-resistant mutants will restore wild-type sensitivity to nitrogen mustard. By contrast the presence of multi-copy vectors containing HNM1, in either a hyper-resistant hnm1 mutant or an HNM1 wild-type, will lead to a novel, mustard-sensitive phenotype unrelated to defects in DNA repair genes. Gene disruption of HNM1 revealed that this gene is nonessential for cells prototrophic for choline (CHO1) but lethal for cells with a cho1 genotype. Sensitivity to nitrogen mustard of wild-type HNM1, but not of hnm1 mutants, depends on the choline content of the growth medium, with cells grown in choline-free medium exhibiting the highest sensitivity. Sequencing of a 300 bp DNA fragment of HNM1 revealed the identity of this gene with the CTR locus, which is responsible for choline transport in Saccharomyces cerevisiae.
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  • 8
    ISSN: 1432-0983
    Keywords: Mutagen hyper-resistance ; Yeast ; Base sequence ; Gene disruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A multi-copy plasmid containing the SNQ3 gene confers hyper-resistance to 4-nitroquinoline-N-oxide (4NQO), Trenimon, MNNG, cycloheximide, and to sulfometuron methyl in yeast transformants. Restriction analysis, subcloning, and DNA sequencing revealed an open reading frame of 1950 bp on the SNQ3-containing insert DNA. Gene disruption and transplacement into chromosomal DNA yielded 4NQO-sensitive null mutants which were also more sensitive than the wild-type to Trenimon, cycloheximide, sulfometuron methyl, and MNNG. Hydropathic analysis showed that the SNQ3-encoded protein is most likely not membrane-bound, while the codon bias index points to low expression of the gene.
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  • 9
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    Current genetics 19 (1991), S. 89-94 
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondria ; Intron ; Mobile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial and nuclear genomes of 21 yeast species belonging to 12 genera have been tested for the presence of sequences similar to seven S. cerevisiae mitochondrial introns (Sc cox1.1,2,3,4,5c, Sc cob.4 and Sc LSU.1) and one K. lactis mitochondrial intron (Kl cox1.2). Some introns, (Sc cox1.4, Sc cob.4, Sc LSU.1 and Kl cox1.2-all group I type), are widely distributed and are found in species with either basidiomycete or ascomycete affinities. This distribution is suggestive of recent sequence transfer between species. The remaining S. cerevisiae introns cross react with an additional species but with no set pattern. Pulsed field gel electrophoretic studies confirm that none of the tested mitochondrial introns cross react with nuclear DNA. These introns are, therefore, mitochondria-specific. Seven strains of K. lactis exhibit striking variability in intron content. In contrast to all mitochondrial introns tested, two introns of nuclear genes (the K. lactis actin gene and the S. cerevisiae RP29B gene) are not detected beyond their source species.
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  • 10
    ISSN: 1432-0983
    Keywords: Yeast ; Pyruvate decarboxylase ; Gene expression ; Codon usage ; Gene fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three structural genes encode the pyruvate decarboxylase isoenzymes in the yeast Saccharomyces cerevisiae. PDC1 and PDC5 are active during glucose fermentation where PDC1 is expressed about six times more strongly than PDC5. Expression of PDC6 is weak and seems to be induced in ethanol medium. Consequently, pdc1Δ pdc5Δ double mutants do not ferment glucose and do not grow on glucose medium. Spontaneous mutants, derived from such a pdc1 pdc5 strain, were isolated which could again ferment glucose. They showed pyruvate decarboxylase activity due to a duplication of PDC6. The second copy of PDC6 was expressed under the control of the PDC1 promoter, which was still present in the pdc1 strain. However, the resulting PDC1-PDC6 fusion gene could only partially substitute for PDC1: to achieve normal growth and high pyruvate decarboxylase activity strains carrying PDC1-PDC6 required a functional PDC5 gene which is dispensable in a PDC1 wild-type background. Thus, expression of PDC5 depends on the state of the PDC1 locus: low in the PDC1 wild-type background and high in PDC1-PDC6 fusion strains and, as shown previously, in pdc1 mutants. The activation of PDC5 expression in PDC1-PDC6 strains may be due to particular properties of the PDC1-PDC6 fusion protein or simply to the weaker expression of PDC1-PDC6 in comparison to the wild-type PDC1 gene.
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  • 11
    ISSN: 1432-0983
    Keywords: AEP2 ; Yeast ; Mitochondria ; ATP synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The temperature-conditional pet mutant, ts379, of Saccharomyces cerevisiae fails to synthesize mitochondrial ATP synthase subunit 9 at the restrictive temperature due to mutation of a single nuclear locus, AEP2. The inability to synthesize subunit 9 correlates with a lowered accumulation of the cognate oli1 mRNA indicating that the AEP2 product is involved in oli1 transcript maturation or stabilization. The AEP2 gene has been isolated in this study from a wild-type yeast genomic library by genetic complementation of ts379 at the restrictive temperature. A 1740 nucleotide open-reading frame was observed that encodes a basic, hydrophilic protein of 67534 Da which possesses a putative mitochondrial address signal. Disruption of chromosomal DNA within this reading frame produced a non-conditional respiratory mutant unable to synthesize subunit 9, identifying the AEP2 gene. Hybridization analyses indicate that AEP2 is located on chromosome XIII and produces a 2.1 kb poly(A)+ transcript. Two additional open-reading frames were found in close proximity to that of AEP2. The three open-reading frames shared no significant homology with entries in several data bases.
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  • 12
    ISSN: 1432-0983
    Keywords: Pulsed field gel-electrophoresis ; S1 nuclease sensitive sites ; Repair ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Repair under non-growth conditions of DNA double-strand breaks (DSB) and chromatin sites sensitive to S1 endonuclease (SSS) induced by 60Cobalt-gamma rays were monitored in repair-competent and deficient strains of Saccharomyces cerevisiae by pulsed field gelelectrophoresis. In stationary-phase cells of a repair-competent RAD diploid, and an excision-deficient rad3-2 diploid, SSS are repaired as efficiently as DSB, whereas in a repair-competent RAD haploid, and a rad 50-1 diploid, neither SSS nor DSB are repaired. The rad18-2 diploid repairs DSB well but is defective in SSS repair. Obviously, SSS repair in yeast chromatin, like DSB repair, depends on recombination, but unlike DSB repair depends additionally on RAD18 function.
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  • 13
    ISSN: 1432-0983
    Keywords: Yeast ; Mistranslation ; ψ-factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chromosomal omnipotent suppressor mutations recovered in ψ+ strains of Saccharomyces cerevisiae were brought into ψ− cytoplasm. SUP46, SUP138 and SUP139 acted as dominant omnipotent suppressors in the ψ− cytoplasm though their suppressor activity was substantially reduced. SUP46 and SUP138 conferred recessive thermosensitivity and antibiotic sensitivity in ψ− cytoplasm as in ψ+ cytoplasm. On the other hand, sup111 through sup115, which acted as recessive omnipotent suppressors in the ψ+ cytoplasm, manifested no, or very low, suppressor activity in the ψ− cytoplasm. They, however, still enhanced the efficiency of the SUP29 tRNA suppressor in ψ− cytoplasm. A multicopy plasmid carrying the wild-type SUP35 gene enhanced the efficiency of sup111 in ψ− cytoplasm.
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  • 14
    ISSN: 1432-0983
    Keywords: Yeast ; Mutant ; p-Fluoro-dl-phenylalanine ; β-Phenethyl-alcohol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary p-Fluoro-dl-phenylalanine (PFP)-resistant mutants which produce a large amount of β-phenethyl-alcohol, a rose-like flavor component, were isolated from the isogenic strains X2180-1A and X2180-1B of Saccharomyces cerevisiae. Cells of these mutants accumulated phenylalanine and tryptophan more than 3-fold times that of wild-type cells, while they accumulated less than half the tyrosine. The activity of prephenate dehydrogenase (PDG) (EC 1.3.1.12) was markedly decreased while that of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase (EC 4.1.2.15) was increased. Genetic analysis revealed that the mutation occurred at the TYR1 locus, encoding PDG, and that the mutated TYR1 gene, tyr1-pfp, caused both PFP resistance and β-phenethyl-alcohol overproduction. This was supported by molecular genetic studies with cloned tyr1-pfp DNA.
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  • 15
    ISSN: 1432-0983
    Keywords: Peptides ; Transport ; Regulation ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The transport of small peptides into the yeast Saccharomyces cerevisiae is subject to complex regulatory control. In an effort to determine the number, and to address the function, of the components involved in peptide transport and its regulation, spontaneous mutants resistant to toxic di- and tripeptides were isolated under inducing conditions. Twenty-four mutant strains were characterized in detail and fell into two phenotypic groups; one group deficient in amino acid-inducible peptide uptake, the other with a pleiotropic phenotype including a loss of peptide transport. Complementation analysis of recessive mutations in 12 of these strains defĩned three groups; ptr1 (nine strains), ptr2 (two strains), and ptr3 (one strain). Isolation and screening of 31 additional N-methyl-N-nitro-N-Nitrosoguanidine (MNNG)-induced, peptide transport-deficient mutants produced one ptr3 and 30 ptr2 strains: no additional complementation groups were detected. Uptake of radiolabeled dileucine was negligible in ptr1 and ptr2 strains and was reduced by 65% and 90% in the two ptr3 mutants, indicating that all strains were defective at the transport step. We conclude that the S. cerevisiae amino acid-inducible peptide transport system recognizes a broad spectrum of peptide substrates and involves at least three components. One gene, PTR3, may play an indirect or regulatory role since mutations in this gene cause a pleiotropic phenotype.
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  • 16
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    Journal of molecular evolution 32 (1991), S. 396-404 
    ISSN: 1432-1432
    Keywords: Yeast ; Mitochondrial DNA ; Polymirphism ; Repeated sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A spontaneously arising mitochondrial DNA (mtDNA) variant ofSaccharomyces cerevisiae has been formed by two exta copies of a 14-bp sequence (TTAATTAAATTATC) being added to a tandem repeat of this unit. Similar polymorphisms in tandemly repeated sequences have been found in a comparison between mtDNAs from our strain and others. In 5850 bp of intergenic mtDNA squence, polymorphisms in tandemly repeated sequences of three or more base pairs occur approximately every 400–500 bp whereas differences in 1–2 bp occur approximately every 60 bp. Some polymorphisms are associated wit optional G+C-rich sequences (GC clusters). Two such optional GC clusters and one A+T repeat polymorphism have been discovered in the tRNA synthesis locus. In addition, the variable presence of large open reading frames are documented and mechanisms for generating intergenic sequence diversity inS. cerevisiae mtDNA are discussed.
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  • 17
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    Journal of molecular evolution 32 (1991), S. 439-442 
    ISSN: 1432-1432
    Keywords: Yeast ; Mitochondrial DNA ; ori ; rep ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Threeori elements (ori 2,ori 5, andori 7) have been sequenced inSaccharomyces cerevisiae strain Dip 2 and compared to the equivalentori elements of a second strain (B). Bothori 2 andori 5 exhibit 98% base matching between strains Dip 2 and B. In contrast, the thirdori element (ori 7) exhibits extensive sequence rearrangements whereby a segment located downstream in the consensus strain occurs within theori structure in Dip 2. This represents a novel polymorphic form of the yeast mitochondrial genome.
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  • 18
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    Journal of paleolimnology 6 (1991), S. 257-260 
    ISSN: 1573-0417
    Keywords: Chrysophyceae ; stomatocysts ; biogenic silica deposition ; polymer gels ; surface pattern ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The utility of classifying chrysophyte stomatocysts by their characteristic honeycomb and ridge patterns is questioned, because a strikingly similar expanding pattern appears on the surface of ionized polymer gels during osmotical swelling as a result of simple physical forces. The rapid accumulation of silicate into a spherical cyst inside a chrysophyte cell appears to be as a physical process sufficiently similar to result in an analogous pattern in microscopic scale. Chrysophyte stomatocysts that possess honeycomb or ridge patterns could be regarded as ‘frozen moments’ of the pattern evolution during the silicate gel phase. As a consequence, such structures should have little taxonomical value.
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  • 19
    ISSN: 1420-9098
    Keywords: Thaumatomyrmex ; taxonomy ; comparative morphology ; predation ; Polyxenidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe, for the first time, the predatory behaviour ofThaumatomyrmex ants on millipedes of the family Polyxenidae, based on field observations ofT. atrox and a field and laboratory study ofT. contumax. The capture of the prey and the removal process of its body-covering setae by the ants before they eat the millipede are described. This specialized behaviour in at least two species of the genus, belonging to two distinct groups of species, indicates a general trend inThaumatomyrmex. We coupled this study with a comparative morphological analysis of the mouthparts and digestive tube of these and otherThaumatomyrmex species. Also, we report the first case of sympatry in the genus, which suggests thatThaumatomyrmex includes several species, and not only one highly variable taxon, as hypothetized earlier.
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  • 20
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    Current genetics 20 (1991), S. 471-474 
    ISSN: 1432-0983
    Keywords: Yeast ; DNA replication ; Chemical mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Incubation of cdc8 mutants of the yeast Saccharomyces cerevisiae in YPD under permissive conditions, when DNA replication is taking place, prior to transfer to restrictive conditions, strongly stimulates induction of cdc + colonies of ethyl methane sulphonate (EMS)- and methyl methane sulphonate (MMS)-treated yeast strains HB23 (cdc8-1/cdc8-3), HB26 (cdc8-3/cdc8-3) and HB7 (cdc8-1/cdc8-1). After diepoxybutane (DEB) treatment, both the induction of cdc + colonies and their stimulation after incubation in YPD under permissive conditions is low. The results obtained show that stimulation of induction of cdc + colonies under permissive conditions occurs not only after UV-treatment, but also after treatment with such mutagens as EMS and MMS.
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  • 21
    ISSN: 1432-0983
    Keywords: Petite mutation ; NUC2 nuclease ; Yeast ; RAD52 ; Ethidium bromide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Defects in the RAD52 gene of the yeast Saccharomyces cerevisiae reduce the levels of the NUC2 endo-exonuclease by approximately 90% compared to the levels in wild-type strains. To examine the potential role of this nuclease in the induction of mitochondrial ‘petite’ mutations, congenic RAD52 and rad52-1 haploids were subjected to treatment with ethidium bromide, a well-known inducer of these mutations. The rad52 strain showed a much higher resistance to ethidium bromide-induced petite formation than the corresponding wild-type strain. Two approaches were taken to confirm that this finding reflected the nuclease deficiency, and not some other effect attributable to the rad52-1 mutation. First, a multicopy plasmid (YEp213-10) carrying NUC2 was transformed into a RAD52 strain. This resulted in an increased fraction of spontaneous petite mutations relative to that seen for the same strain without the plasmid and sensitized the strain carrying the plasmid to peptite induction by ethidium bromide treatment. Second, a strain having a nuc2 allele that encodes a temperaturesensitive nuclease was treated with ethidium bromide at the restrictive and permissive temperatures. Petite induction was reduced under restrictive conditions. Enzyme assays revealed that the RAD52 (YEp213-10) strain had the highest level of antibody-precipitable NUC2 endo-exonuclease whereas the nuc2 and rad52 mutants had the lowest levels. Furthermore, addition of ethidium bromide to the reaction mixture stimulated the activity of the nuclease on double-stranded DNA. Peptite induction by antifolate-mediated thymine nucleotide depletion was also inhibited by inactivation of RAD52 indicating that the effect of reduced NUC2 endo-exonuclease was not restricted to ethidium bromide treatment. Taken collectively, these results indicate that the NUC2 gene product functions in the production of mitochondrial petite mutations.
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  • 22
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    Current genetics 20 (1991), S. 1-3 
    ISSN: 1432-0983
    Keywords: Yeast ; Transformation ; Ethanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A technique is described in which ethanol is used to improve the genetic transformation of intact yeast (Saccharomyces cerevisiae) cells pretreated with LiAc and PEG. Transformation efficiency was increased with increasing concentrations of ethanol with a peak at 10% concentration. The effect varies with different yeast strains and plasmids and up to a maximum of a 15-fold increase was observed.
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  • 23
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    Current genetics 20 (1991), S. 25-31 
    ISSN: 1432-0983
    Keywords: Yeast ; TSM1 sequence ; Essential gene ; MAT distal cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have cloned the region from MAT to THR4 on chromosome III of Saccharomyces cerevisiae. Although the region is only 15 kb, the two loci are genetically separated by 22 cM. This is in sharp contrast to the very low level of recombination (2 cM in 22 kb) that is observed in the adjacent CRY1-MAT interval, and suggests that there may be a “hot spot” for recombination in the MAT-THR4 region. The DNA sequence of the first 4.4 kb distal to MAT reveals an open reading frame that we have identified as the essential gene, TSM1. Surprisingly, the TSM1 open reading frame of 1 410 amino acids extends into the MAT locus, such that the 3′-end of the MATα1 transcript ends 15 bp from the 3′-end of the TSM1 open reading frame.
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  • 24
    ISSN: 1432-0983
    Keywords: Yeast ; Enhancer ; Transcriptional elements ; Transcriptional factors ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Though highly complex enhancers found in animal cells have not been reported to occur in yeasts they are able to activate the transcription of adjacent genes in yeast cells. Saccharomyces cerevisiae expresses a large number of nuclear proteins that are able to recognize, and specifically bind to, the enhancer sequences of the SV40 animal tumor virus. The complexity of proteins that interact with different elements of the animal enhancers is similar in yeast and animal cell nuclear extracts. Most enhancer motifs, recognized by known trans-acting factors, are protected in footprinting experiments by yeast nuclear proteins.
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  • 25
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Ergosterol ; Squalene synthetase ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ERG9 gene of Saccharomyces cerevisiae has been cloned by complementation of the erg9-1 mutation which affects squalene synthetase. From the 5kkb insert isolated, the functional gene has been localized on a DNA fragment of 2.5 kb. The presence of squalene synthetase activity in E. coli bearing the yeast DNA fragment isolated, indicates that the structural gene encoding squalene synthetase has been cloned. The sequence of the 2.5 kb fragment contains an open reading frame which could encode a protein of 444 amino acids with a deduced relative molecular mass of 51 600. The amino acid sequence reveals one to four potential transmembrane domains with a hydrophobic segment in the C-terminal region. The N-terminus of the deduced protein strongly resembles the signal sequence of yeast invertase suggesting a specific mechanism of integration into the membranes of the endoplasmic reticulum.
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  • 26
    ISSN: 1432-0983
    Keywords: Mitochondria ; Intron ; Telomere ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The junctions between X and Y′ subtelomeric repeats in Saccharomyces cerevisiae usually contain a stretch of telomere sequences, (G1–3T)n. Two of three cloned X-Y′ junctions from strain YP1 have a replacement of about 200 bp of X, the internal telomere sequence, and 49 bp of Y′ by a 292 bp sequence. The first 227 bp of this insertion sequence are 100% identical to the fourth intron of cytochrome b. The rest of the insertion has homology to an unknown dispersed nuclear sequence. Recombination among subtelomeric regions can explain the nuclear distribution of this sequence and why telomeres can trap and maintain sequences that would otherwise be lost.
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  • 27
    ISSN: 1432-0983
    Keywords: In vitro mutagenesis ; PET-genes ; RNA-leader ; Ribosomal scanning ; Yeast
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    Notes: Summary We report that the major transcription start sites of the yeast PET gene SCO1 are located at positions-149 and -125 relative to the AUG initiation codon of the SCO1 reading frame. The leader sequences of the resulting mRNAs possess a single AUG codon at position-49, which initiates a short open reading frame of three amino acids. The recent finding of a similar situation in the case of the PET gene CBS1 prompted us to address the question as to whether these AUG codons might play some role in the expression of these PET genes. After removal of the upstream AUG codons by site-directed mutagenesis, expression was monitored by use of lacZ fusions and compared to the respective wildtype constructs. Our data show that under all growth conditions tested the leader-contained AUG initiation codons have no significant influence on the expression of both PET genes.
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  • 28
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    Biology and philosophy 6 (1991), S. 255-274 
    ISSN: 1572-8404
    Keywords: Classification ; diagrams ; evolution ; history ; natural history ; natural system ; ornithology ; phylogeny ; representation ; systematics ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract ‘The Natural System’ is the abstract notion of the order in living diversity. The richness and complexity of this notion is revealed by the diversity of representations of the Natural System drawn by ornithologists in the Nineteenth Century. These representations varied in overall form from stars, to circles, to maps, to evolutionary trees and cross-sections through trees. They differed in their depiction of affinity, analogy, continuity, directionality, symmetry, reticulation and branching, evolution, and morphological convergence and divergence. Some representations were two-dimensional, and some were three-dimensional; n-dimensional representations were discussed but never illustrated. The study of diagrammatic representations of the Natural System is made difficult by the frequent failure of authors to discuss them in their texts, and by the consequent problem of distinguishing features which carried meaning from arbitrary features and printing conventions which did not. Many of the systematics controversies of the last thirty years have their roots in the conceptual problems which surrounded the Natural System in the late 1800s, problems which were left unresolved when interest in higher-level systematics declined at the turn of this century.
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  • 29
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    Molecular genetics and genomics 230 (1991), S. 241-250 
    ISSN: 1617-4623
    Keywords: Yeast ; Saccharomyces cerevisiae ; Adenylyl cyclase ; CDC25 ; RAS
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    Topics: Biology
    Notes: Summary The TFS1 gene of Saccharomyces cerevisiae is a dosage-dependent suppressor of cdc25 mutations. Overexpression of TFS1 does not alleviate defects of temperature-sensitive adenylyl cyclase (cdc35) or ras2 disruption mutations. The ability of TFS1 to suppress cdc25 is allele specific: the temperature-sensitive cdc25-1 mutation is suppressed efficiently but the cdc25-5 mutation and two disruption mutations are only partially suppressed. TFS1 maps to a previously undefined locus on chromosome XII between RDN1 and CDC42. The DNA sequence of TFS1 contains a single long open reading frame encoding a 219 amino acid polypeptide that is similar in sequence to two mammalian brain proteins. Insertion and deletion mutations in TFS1 are haploviable, indicating that TFS1 is not essential for growth.
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  • 30
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    Molecular genetics and genomics 226 (1991), S. 97-106 
    ISSN: 1617-4623
    Keywords: Yeast ; Linear plasmid ; Saccharomyces kluyveri ; Kluyveromyces lactis ; Killer plasmid
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    Topics: Biology
    Notes: Summary We have determined the complete nucleotide sequence of the linear DNA plasmid, pSKL, isolated from Saccharomyces kluyveri. Sequence analysis showed that pSKL has a high (A+T) content of 71.7%, and that there are 10 open reading frames (ORFs) larger than 250 nucleotides. All 10 ORFs were shown to be transcribed in S. kluyveri cells by S1 nuclease mapping analysis. The localization of ORFs, direction of transcription, and the predicted amino acid sequences of each ORF were quite similar to that of pGKL2, one of the killer plasmids found in Kluyveromyces lactis. The amino acid sequences of the largest two ORFs (ORF2 and ORF6) have homology with several DNA polymerases and RNA polymerases, respectively.
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  • 31
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    Molecular genetics and genomics 226 (1991), S. 145-153 
    ISSN: 1617-4623
    Keywords: Retrotransposons ; Reverse transcription ; Ty elements ; Yeast
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    Topics: Biology
    Notes: Summary Transposition of the yeast transposable element, Ty, has been shown to require a reverse transcription process. By analysing the extrachromosomal Tyspecific nucleic acid molecules associated with overproduced Ty virus-like particles (Ty-VLPs), we identified several reverse transcribed cDNA strands. Most of them resemble the characteristic intermediates of the reverse transcription process described for authentic retroviruses: a (−) strong-stop DNA strand covalently bound to an RNA primer, two elongated (−) strands with one or two long terminal repeat (LTR) sequences and a (+) strong-stop DNA. Surprisingly, complete (+) strands and full-length linear duplex Ty DNA could not be detected. The structural features of two additional (÷) strands may indicate some differences between the mechanisms of (+) strand synthesis in Ty and other retrotransposons or retroviruses.
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  • 32
    ISSN: 1617-4623
    Keywords: Yeast ; Arginine ; Sequence ; Regulation ; Control region
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    Notes: Summary In Saccharomyces cerevisiae, the ARG5,6 gene encodes acetylglutamyl-P reductase and acetylglutamate kinase, two arginine anabolic enzymes which are localized in the mitochondria. The synthesis of both enzymes is co-ordinately controlled by arginine and by three regulatory proteins (ARGRI, ARGRII, and ARGRIII). The ARG5,6 gene was cloned by complementation of an arg5 mutant strain. A subclone containing an EcoRI fragment of about 3.2 kb which complements the arginine requirement was sequenced. This 3163 by sequence contains only one long open reading frame of 2589 nucleotides encoding a protein of 863 amino acids. The size of this protein is in agreement with the length of the unique transcript determined by Northern hybridization. The measurements of ARG5,6 mRNA under various regulatory conditions show no correlation with the enzyme levels. As in other arginine biosynthetic and catabolic genes, the regulation by arginine through the three ARGR proteins thus involves a post-transcriptional control mechanism. By in vitro mutagenesis we created point mutations and deletions in the 5′ non-coding region of the ARG5,6 gene which allowed us to define the primary target of ARGR control. Specific regulation involves two regions: one located between the putative TATA element and the transcriptional initiation site and the second between this site and the first ATG.
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  • 33
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    Molecular genetics and genomics 229 (1991), S. 413-420 
    ISSN: 1617-4623
    Keywords: SCO1 ; Cytochrome oxidase ; Membrane protein ; Mitochondria ; Yeast
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    Topics: Biology
    Notes: Summary The SCO1 gene of Saccharomyces cerevisiae encodes a 30 kDa protein which is specifically required for a post-translational step in the accumulation of subunits 1 and 2 of cytochrome c oxidase (COXI and COXII). Antibodies directed against a β-Gal::SCO1 fusion protein detect SCO1 in the mitochondrial fraction of yeast cells. The SCO1 protein is an integral membrane protein as shown by its resistance to alkaline extraction and by its solubilization properties upon treatment with detergents. Based on the results obtained by isopycnic sucrose gradient centrifugation and by digitonin treatment of mitochondria, SCO1 is a component of the inner mitochondrial membrane. Membrane localization is mediated by a stretch of 17 hydrophobic amino acids in the amino-terminal region of the protein. A truncated SCO1 derivative lacking this segment, is no longer bound to the membrane and simultaneously loses its biological function. The observation that membrane localization of SCO1 is affected in mitochondria of a rho 0 strain, hints at the possible involvement of mitochondrially coded components in ensuring proper membrane insertion.
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  • 34
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    Molecular genetics and genomics 225 (1991), S. 363-368 
    ISSN: 1617-4623
    Keywords: Yeast ; Metallothionein gene ; Cadmium resistance
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    Topics: Biology
    Notes: Summary A 3.3 kb fragment of yeast genomic DNA was isolated by screening a genomic library constructed in the high copy number 2 micron plasmid YEp351 vector for clones capable of enhancing the degree of resistance of Saccharomyces cerevisiae strain MW3070-8B to cadmium. The insert contained two complete copies of the CUP1 gene open reading frame (183 bp), including the upstream promoter sequences (450 bp) with two conserved metal responsive cis-acting elements. Northern analysis showed that addition of cadmium (0.02 μM) or copper (50 μM) to overnight liquid cultures of yeast induced expression of CUP1 transcripts from both chromosomal and plasmid-borne gene copies. The cloned 3.3 kb DNA in a high copy number plasmid restored copper resistance to the sensitive strain LS70-313Δ, deleted for the CUP1 gene (cup1Δ), but failed to restore cadmium resistance. Thus, CUP1 gene expression in yeast appears to be influenced differently by cadmium and copper ions. Resistance to heavy metal poisoning resulted from enhanced gene product levels attributable to amplification of the CUP1 gene as well as to increased transcriptions. Two distinct gene product levels mediate cadmium and copper resistance; a higher gene product level was required to confer cadmium resistance.
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  • 35
    ISSN: 1617-4623
    Keywords: Meiosis ; Sporulation ; Northern hybridization ; Regulatory circuit ; Yeast
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    Notes: Summary The SGA1 gene encoding glucoamylase is specifically expressed late in meiotic development of the yeast Saccharomyces cerevisiae. We found that accumulation of both enzyme activity and transcripts was regulated negatively by both nutritional signals and a haploid-specific negative regulator gene of meiosis, RME1, and positively by the inducer genes for meiosis, IME1 and IME2. To study the role of sequences upstream of the SGA1 gene in its expression and regulation, we generated internal deletions in the 5′ non-coding region of the gene and chimeric genes with portions of the upstream sequence inserted into a reporter gene. By analyzing the expression of these genes, we have identified both a 19 by upstream activation sequence (UAS) and a 49 by negatively regulating element (NRE). The UAS activated transcription with no requirement for heterozygosity at the mating-type locus, but this activation was still under negative control by nutrients. The NRE showed no UAS-like activity but conferred IME2-dependent (or meiosis-specific) expression on a heterologous promoter. These results suggest that meiosis-specific expression of the SGA1 gene is established by a regulatory hierarchy including positive and negative factors, the actions of which are mediated through the two separate upstream regulatory elements, UAS and NRE, respectively. Also, that two independently acting cascades exist for the regulation of SGA1 expression: one transduces both the mating-type and nutritional signals and includes the IME2 product, which acts to relieve the repression through NRE ; and another transduces only the nutritional signal independently of the above pathway and inhibits positive factors acting on UAS.
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  • 36
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    Molecular genetics and genomics 227 (1991), S. 127-136 
    ISSN: 1617-4623
    Keywords: Yeast ; Killer toxin ; Immunity
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    Topics: Biology
    Notes: Summary A cDNA copy of the M2 dsRNA encoding the K2 killer toxin ofSaccharomyces cerevisiae was expressed in yeast using the yeastADH1 promoter. This construct produced K2-specific killing and immunity functions. Efficient K2-specific killing was dependent on the action of the KEX2 endopeptidase and the KEX1 carboxypeptidase, while K2-specific immunity was independent of these proteases. Comparison of the K2 toxin sequence with that of the K1 toxin sequence shows that although they share a common processing pathway and are both encoded by cytoplasmic dsRNAs of similar basic structure, the two toxins are very different at the primary sequence level. Site-specific mutagenesis of the cDNA gene establishes that one of the two potential KEX2 cleavage sites is critical for toxin action but not for immunity. Immunity was reduced by an insertion of two amino acids in the hydrophobic amino-terminal region which left toxin activity intact, indicating an independence of toxin action and immunity.
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  • 37
    ISSN: 1617-4623
    Keywords: Yeast ; Mitochondria ; Frameshift ; Suppression ; Restriction
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    Topics: Biology
    Notes: Summary The +1 frameshift mutation, M5631, which is located in the gene (oxi1) for cytochrome c oxidase II (COXII) of the yeast mitochondrial genome, is suppressed spontaneously to a remarkably high extent (20%–30%). The full-length wild-type COXII produced as a result of suppression allows the mutant strain to grow with a “leaky” phenotype on non-fermentable medium. In order to elucidate the factors and interactions involved in this translational suppression, the strain with the frameshift mutation was mutated by MnCl2 treatment and a large number of mutants showing restriction of the suppression were isolated. Of 20 mutants exhibiting a strong, restricted, respiration-deficient (RD) phenotype, 6 were identified as having mutations in the mitochondrial genome. Furthermore, genetic analyses mapped one mutation to the vicinity of the gene for tRNAPro and two others to a region of the tRNA cluster where two-thirds of all mitochondrial tRNA genes are encoded. The degree of restriction of the spontaneous frameshift suppression was characterized at the translational level by in vivo 35S-labeling of the mitochondrial translational products and immunoblotting. These results showed that in some of these mutant strains the frameshift suppression product is synthesized to the same extent as in the leaky parent strain. It is suggested that more than one +1 frame-shifted product is made as a result of suppression in these strains: one is as functional as the wild-type COXII, the other(s) is (are) non-functional and prevent leaky growth on non-fermentable medium. A possible mechanism for this heterogenous frameshift suppression is discussed.
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  • 38
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    Plant systematics and evolution 175 (1991), S. 55-72 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Dactylorhiza ; D. maculata ; D. fuchsii ; D. saccifera ; D. caramulensis ; Biostatistics ; multivariate analysis ; taxonomy ; morphology ; Flora of Western-Europe
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    Notes: Abstract Multivariate analysis tools are exploited on a data set composed of quantitative characteristics collected on 35 populations of plants of theDactylorhiza maculata (L.)Soó group from Western-Europe. These samples lead to four well-defined clusters; this, together with qualitative, cytological and ecological arguments, allows for the recognition of four specific entities:D. maculata s.str.,D. fuchsii (Druce)Soó,D. saccifera (Brongn.)Soó andD. caramulensis (Vermeulen)Tyteca. It is concluded that the floral characters play an essential role in the taxonomical distinction. It also appears that the set of characters measured, as well as the methods exploited, are especially well-suited and valuable tools for the morphological study of the genusDactylorhiza.
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  • 39
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    Plant systematics and evolution 175 (1991), S. 139-160 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Restionaceae ; Rhodocoma ; Speciation ; phylogeny ; culm anatomy ; rhizome anatomy ; morphology ; taxonomy ; Flora of Africa
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    Topics: Biology
    Notes: Abstract The vegetative and reproductive morphology, culm and rhizome anatomy and seed surface micromorphology ofRhodocoma are described. It is shown that this variation is best contained by recognizing three new species in the genus. These new taxa are described, and the phylogeny of the genus is investigated by cladistic analysis. The environmental parameters and distributions of the species are related to the cladogram. This suggests that the species are at present ecologically separated, and indicates that the speciation may have been sympatric. This is the first support for the hypothesis that sympatric speciation may have been important in the speciose Cape flora.
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  • 40
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    Plant systematics and evolution 176 (1991), S. 1-10 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Chenopodiaceae ; Beta bulgaris L ; Germplasm collections ; taxonomy ; single linkage cluster analysis ; principal component analysis ; variation patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The objective of this study was to contribute to a better understanding of the variation pattern in leaf beets. 42 biennial samples from a total of 74 entries were described by 17 characters. A group of presumably less selected leaf beets (group A) with narrow petioles was separated from more advanced cultivars by single linkage cluster (SLCA) and principal component analysis (PCA). SLCA sorted the more advanced cultivars into two groups (B and C) based on a simply inherited trait, the leaf colour. These two groups could virtually not be discerned by PCA. Group A contained germplasm similar to provar.vulgaris sensuHelm whereas accessions within group B and C did not easily fit into provar.flavescens. It seems that classical taxonomy does not predict the features of leaf beets precisely enough. It is suggested that this problem can be solved by replacing classical taxonomy in the case of leaf beets by a descriptive database.
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  • 41
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    Plant systematics and evolution 176 (1991), S. 75-123 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Inuleae s. str. ; Cladistics ; phylogeny ; taxonomy
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    Notes: Abstract The interrelationships of the tribeInuleae s. str. have been analysed with a computerized parsimony program (Hennig 86), using theArctotideae as functional outgroup. The results are illustrated with a cladogram and a strict consensus tree. A detailed character discussion is presented. Descriptions of all genera are supplied with brief notes on distribution, references to chemical investigations, and chromosome numbers. Lists of recognized species are also presented in connection to each genus, respectively. 21 new combinations are made, one new genus,Xerolekia A. Anderb., is described,Mollera is reduced to a synonym ofCalostephane, and the genusDuhaldea is resuscitated.Anisopappus was found to be a paraphyletic basal group in the tribe. The paleate generaAsteriscus, Nauplius, Ighermia, Buphthalmum, andXerolekia form one monophyletic group,Inula and other, similar genera were found to constitute the ancestral complex of thePulicaria group.
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  • 42
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    Plant systematics and evolution 176 (1991), S. 145-177 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Plucheeae ; Cladistics ; phylogeny ; taxonomy
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    Notes: Abstract The tribePlucheeae (Benth.)A. Anderb., has been analysed cladistically by means of a computerized parsimony program (Hennig 86), using theArctotideae as outgroup. The results of the analysis are presented in a consensus tree and one cladogram. Four major monophyletic subgroups can be recognized: TheColeocoma group (3 genera), thePterocaulon group (3 genera), theLaggera group (6 genera), and thePluchea group (12 genera). All recognized genera are described and most genera are supplied with taxonomical notes including comments on their taxonomic status. Genera such asBlumea, Pluchea, andEpaltes are demonstrated to be unnatural assemblages.Monarrhenus andTessaria are both closely related to thePluchea complex. The old generic nameLitogyne Harv. has been taken up for one species ofEpaltes, the genusRhodogeron is reduced to a synonym ofSachsia, and the following new combinations are made;Litogyne gariepina (DC.)A. Anderb., andSachsia coronopifolia (Griseb.)A. Anderb.
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  • 43
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    Plant systematics and evolution 178 (1991), S. 43-53 
    ISSN: 1615-6110
    Keywords: Gymnosperms ; Pinaceae ; Pinus ; Seed proteins ; SDS-PAGE ; taxonomy
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    Topics: Biology
    Notes: Abstract Seed storage proteins have proved to be a powerful biochemical marker for taxonomic research, but they have not been extensively employed in forest tree studies. In order to improve the understanding of the taxonomy of the genusPinus, total seed proteins of 12 pine species have been analyzed by means of SDS-PAGE (Sodium dodecylsulphate-polyacrylamide gel electrophoresis). The results showed the presence, in the genusPinus, of two main sub-taxa, corresponding to the subgeneraHaploxylon andDiploxylon. Differences and affinities between Mediterranean pine species were found in agreement with classification ofKlaus (1989).
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  • 44
    ISSN: 1617-4623
    Keywords: SNF2 sequence ; Transcriptional regulator ; Gene expression ; Glucoamylase ; Yeast
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    Topics: Biology
    Notes: Summary We have cloned and sequenced the GAM1 gene which is required for transcription of the STA1 gene encoding an extracellular glucoamylase in Saccharomyces cerevisiae var. diastaticus. Complementation tests indicated that GAM1 is the same gene as SNF2 which is required for derepression of the SUC2 gene encoding invertase. Accumulation of SNF2 RNA was not regulated by the GAM2 and GAM3 genes which are also required for STA1 expression. The SNF2 gene was predicted to encode a 194 kDa highly charged protein with a glutamine-rich tract. A bifunctional SNF2-lacZ fusion protein was shown by immunofluorescence microscopy to be localized to the nucleus, suggesting that the SNF2 protein is located in the nucleus.
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  • 45
    ISSN: 1617-4623
    Keywords: Protein kinase ; Yeast ; CDC28 ; Cell cycle
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    Notes: Summary A novel protein kinase homologue (KNS1) has been identified in Saccharomyces cerevisiae. KNS1 contains an open reading frame of 720 codons. The carboxy-terminal portion of the predicted protein sequence is similar to that of many other protein kinases, exhibiting 36% identity to the cdc2 gene product of Schizosaccharomyces pombe and 34% identity to the CDC28 gene product of S. cerevisiae. Deletion mutations were constructed in the KNS1 gene. kns1 mutants grow at the same rate as wild-type cells using several different carbon sources. They mate at normal efficiencies, and they sporulate successfully. No defects were found in entry into or exit from stationary phase. Thus, the KNS1 gene is not essential for cell growth and a variety of other cellular processes in yeast.
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  • 46
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    Molecular genetics and genomics 229 (1991), S. 353-356 
    ISSN: 1617-4623
    Keywords: DNA polymerase ; Gene conversion ; Yeast
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    Notes: Summary In Saccharomyces cerevisiae, three different DNA polymerase complexes, POLI, POLII and POLIII, are known to be involved in DNA replication. The catalytic subunit of POLIII is encoded by the essential CDC2 gene. The existence of different thermosensitive non-complementing mutants of CDC2 offers the possibility of using a genetic approach to investigate the involvement of POLIII in induced gene conversion. When cdc2 heteroallelic cells were irradiated and incubated under restrictive conditions, almost no induction of thermoresistant cells could be detected, suggesting an essential role for POLIII in mitotic gene conversion events.
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  • 47
    ISSN: 1617-4623
    Keywords: Translational activation ; Cytochrome b ; Mitochondria ; Yeast ; CRS1 ; CBS2
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    Notes: Summary The products of the nuclear genes CBS1 and CBS2 are both required for translational activation of mitochondrial apocytochrome b in yeast. We report the intramitochondrial localization of both proteins by use of specific antisera. Based on its solubilization properties the CBS1 protein is presumed to be a component of the mitochondrial membrane; the detergent concentrations needed to release CBS1 from mitochondria are almost the same as for cytochrome c 1. In contrast, CBS2 behaves like a soluble protein, with some characteristics of a membrane-associated protein. A model is presented for translational activation of cytochrome b, which might also be applicable to translational regulation of other mitochondrial genes.
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  • 48
    ISSN: 1617-4623
    Keywords: Yeast ; Transcription ; a- and α-specific genes ; MCM1 ; STE12
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    Notes: Summary We have examined the relative contributions of MCM1 and STE12 to the transcription of the a-specific STE2 gene by using a 367 by fragment from the STE2 5′-noncoding region to drive expression of a reporter lacZ gene. Mutation of the MCM1 binding site destroyed MCM1 · α2-mediated repression in α cells and dramatically reduced expression in a cells. The residual expression was highly stimulated by exposure of cells to pheromone. Likewise, the loss of STE12 function reduced lacZ expression driven by the wild-type STE2 fragment. In the absence of both MCM1 and STE12 functions, no residual expression was observed. Thus, the STE2 fragment appears to contain two distinct upstream activation sequences (UASs), one that is responsible for the majority of expression in cells not stimulated by pheromone, and one that is responsible for increased expression upon pheromone stimulation. In further support of this idea, a chemically synthesized version of the STE2MCM1 binding site had UAS activity, but the activity was neither stimulated by pheromone nor reduced in ste12 mutants. Although transcription of aspecific genes also requires both MCM1 and STE12, these genes differ from a-specific genes in that they have a single, MCM1-dependent UAS system. The activity of the minimal 26 by UAS from the α-specific STE3 gene was both stimulated by pheromone and reduced in ste12 mutants. These data suggest that at α-specific genes STE12 and MCM1 exert their effects through a single UAS.
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  • 49
    ISSN: 1617-4623
    Keywords: Mitochondria ; Yeast ; Protein targeting ; PET2858 ; Inner membrane protease 1
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    Notes: Summary The nuclear yeast mutant pet ts2858 is defective in the removal of pre-sequences from the mitochondrially encoded cytochrome oxidase subunit II (COXII) and the processing intermediate of cytochrome b 2 (Cytb 2), a nuclear gene product. In order to identify the genetic lesion in this mutant we have cloned and characterized a DNA region which complements the pet ts2858 mutation. The DNA sequence revealed three open reading frames, one of which is responsible for the complementation. A 570 by reading frame represents the structural gene PET2858, as demonstrated by in vitro mutagenesis, gene expression from a foreign promoter, and allelism tests. PET2858 encodes a 21.4 kDa protein, which is essential for growth on non-fermentable carbon sources and for the proteolytic processing of COXII and the Cytb 2 intermediate. When the N-terminus of the PET2858 protein is fused to a reporter protein, the resulting hybrid molecule is imported into mitochondria. Interestingly, the N-terminal half of the deduced PET2858 protein exhibits 30.7% amino acid identity to the leader peptidase of Escherichia coli. These results suggest that PET2858 codes for a mitochondrial inner membrane protease (IMP1) or at least a subunit of it. This protease is involved in protein processing and export from the mitochondrial matrix.
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  • 50
    ISSN: 1573-5060
    Keywords: Eggplant ; non-tuberous Solanum ; chloroplast DNA ; taxonomy ; species relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Total chloroplast DNA (cpDNA) from Solanum incanum, a wild relative of eggplant, was used to probe total DNA of Solanum melongena (eggplant). The DNA fragments detected were the same as observed using purified chloroplast DNA. Chloroplast DNAs were also analysed for nine species of Solanum that are cross-compatible with eggplant: S. aethiopicum, S. anguivi, S. gilo, S. incanum, S. indicum, S. integrifolium, S. macrocarpon, S. olivare and S. panduriforme. Restriction fragments generated by eight enzymes were recorded as present or absent, and a matrix for all fragment positions, species and enzymes was used for cluster analysis. In the resulting dendrogram, the species tested formed three distinct groups: (1) S. aethiopicum, S. anguivi, S. gilo, S. indicum, S. integrifolium and S. olivare, (2) S. incanum, S. melongena and S. panduriforme, (3) S. macrocarpon. Six species of the first group belonging to section Oliganthes appears more closely related to the second group members belonging to section Melongena than does S. macrocarpon, which also belongs to section Melongena. Within the second group, S. panduriforme is slightly more like eggplant than is S. incanum.
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  • 51
    ISSN: 1573-5060
    Keywords: chloroplast DNA ; Lens ; polymorphism ; restriction fragments ; taxonomy
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Chloroplast DNA restriction fragment lenght polymorphisms (RFLP) were used to examine the taxonomic relationships of cultivated and wild lentil (Lens Miller) species and identify the extent of genetic variation in this genus. Twelve accessions representing all Lens subspecies were digested with four hexanucleotide-recognizing restriction endonucleases. These digests randomly surveyed 540 base pairs, or 0.4% of the approximately 125 kilobase lentil chloroplast genome. A high degree of gragment length conservation was seen among members of crossability group I, i.e., L. c. ssp. culinaris, L. c. ssp. orientalis and L. c. ssp. odemensis. Accessions of the two subspecies comprising crossability group II, i.e., L. n. ssp. nigricans and L. n. ssp. ervoides, showed the greatest amount of variation when compared to the cultivated lentil, L. c. ssp. culinaris. Limited variation was observed within subspecies except for L. n. ssp. nigricans, where accessions of the normal cytotype were highly polymorphic to those of the differentiated cytotype. Chloroplast DNA RFLPs reaffirm hypotheses that propose L. c. ssp. orientalis as the progenitor to the cultivated lentil. The implications of this study on taxonomy and genetic resources is also discussed.
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  • 52
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    Plant and soil 137 (1991), S. 167-170 
    ISSN: 1573-5036
    Keywords: azolla ; DNA polymorphisms ; isoenzymes ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract TheAnabaena-Azolla association has proved to be an effective biofertilizer in tropical regions of wetland rice production. Three neotropical host species,A. microphylla, A. caroliniana, andA. mexicana, are similar in vegetative morphology (growth habits, frond dimensions, trichome cell number) and ecophysiology (relative heat tolerance). They were observed during our investigation to also be genetically alike and distinct from other taxa.
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  • 53
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    Hydrobiologia 209 (1991), S. 141-153 
    ISSN: 1573-5117
    Keywords: Bulinus ; Schistosoma intercalatum ; Africa ; São Tomé ; taxonomy ; schistosomiasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract São Tomé Island has 3 known taxa of freshwater gastropod, here identified to species for the first time; Neritina afra Sowerby, Ferrissia eburnensis Binder and a distinctive form of Bulinus forskalii (Ehrenberg). The Bulinus acts as intermediate host for the parasite Schistosoma intercalatum Fisher, the cause of human schistosomiasis in foci of infection detected in recent years on São Tomé. A morphological characterization of this snail is presented, in respect of the shell, radula and copulatory organ. It is compared with B. forskalii populations sampled on the African mainland (Nigeria, Cameroon, Gabon and Angola) and with related taxa. Despite differences in the shell from the commonly found form of B. forskalii it seems appropriate to identify the São Tomé population as an extreme conchological variant of this taxon.
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    Hydrobiologia 209 (1991), S. 169-173 
    ISSN: 1573-5117
    Keywords: Anuraeopsis ; taxonomy ; morphology ; Weber's organ ; stratified karstic lakes ; chemocline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two taxa of Anuraeopsis, A. fissa fissa (Gosse, 1851) and A. miraclei nov. spec. occur in meromictic and stratified karstic lakes in Spain. They coexist, but may also live separated in different strata with A. miraclei restricted to a zone near the chemocline, characterized by low temperatures and low oxygen concentrations. The two Anuraeopsis species differ from each other in size, shape, structure and thickness of the lorica, size of the trophi elements, shape of Weber's organ, and egg-structure.
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    Hydrobiologia 212 (1991), S. 221-230 
    ISSN: 1573-5117
    Keywords: Anostraca ; taxonomy ; biogeography ; ecology ; Branchipus ; Spain
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    Topics: Biology
    Notes: Abstract Branchipus cortesi, n. sp. (Anostraca, Branchipodidae) is characterized by the broadly enlarged distal segments of male antenna 2, and a combination of morphological features concerning thoracic limbs, abdominal segments and egg morphology. The species occurs in temporary fresh water bodies in flatlands with temperate Mediterranean climate; it is distributed in the south-western part of Spain. Our study includes a morphological analysis using optical and scanning electronic microscopes. Questions about ecology and distribution of the new species are also discussed.
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  • 56
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    Hydrobiologia 212 (1991), S. 261-266 
    ISSN: 1573-5117
    Keywords: Anostraca ; taxonomy ; zoogeography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fairy shrimp Chirocephalus brevipalpis (Orghidan, 1953) has been found in the Srem-district, Northern Yugoslavia, at the southern margin of the Pannonian lowland. It is the second record of the species, which had been reported only from Banat province, Romania. Since the specimens from Yugoslavia show some morphological differences with the typical form, a detailed description and illustration of essential taxonomic features in each sex are presented. The specific characters of the population of Srem are not sufficient to establish a new species, and fall within the intraspecific variability of Chirocephalus brevipalpis.
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    Hydrobiologia 221 (1991), S. 1-17 
    ISSN: 1573-5117
    Keywords: cystocarps ; Gelidium ; morphological variability ; Pterocladia ; taxonomy
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    Topics: Biology
    Notes: Abstract Unilocular cystocarps, with ostioles opening to one frond surface, have traditionally distinguished Pterocladia from Gelidium, described as having bilocular cystocarps, with ostioles opening to both surfaces; however, unequally developed locules have been described in Pterocladia and differences in cystocarpic architecture between Pterocladia capillacea and the type species of the genus, P. lucida, have been recently found. As heterogeneity in cystocarp architecture raises questions of basic intergeneric distinction, a survey of reproductive morphology of species in both genera is presented in this study. Six morphologically-different types of cystocarps are distinguished among the five species of Pterocladia and the seven species of Gelidium examined.
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    Hydrobiologia 225 (1991), S. 37-43 
    ISSN: 1573-5117
    Keywords: Iberian Cladocera ; taxonomy ; ecology ; biogeography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A checklist of 88 freshwater Cladocera from the Iberian Peninsula is given, based on the examination of approximately 1500 samples collected from all parts of the peninsula from 1976 to 1989. Ecology and species assemblages are considered. Distribution of the species versus regional limnology of the Iberian Peninsula is discussed.
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    Hydrobiologia 226 (1991), S. 17-27 
    ISSN: 1573-5117
    Keywords: Branchinecta ; Anostraca ; taxonomy ; zoogeography ; Yugoslavia
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    Topics: Biology
    Notes: Abstract The genus Branchinecta Verrill, 1869 is represented in Yugoslavia by two species: Branchinecta ferox (Milne-Edwards, 1840) and Branchinecta orientalis G.O. Sars, 1901. The first species was collected in the steppe-like province of Banat, Pannonian Lowland, and in the lowland around the Skadar Lake, Montenegro, the second only in the province of Banat. On the basis of rich material of both species, a detailed study of the most essential morphological characters has been carried out and comparisons have been made with data in the literature. In B. ferox, significant morphological deviations are not found, whereas, in B. orientalis, essential features are clearly ascertained which were previously unknown or were not stated with sufficient precision. B. ferox is known to appear in small, temporary, natronsoda water rainpools, while B. orientalis has been found in a large temporary inundation pool with a high content of natronsoda and salt in the water.
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  • 60
    ISSN: 1573-5117
    Keywords: taxonomy ; Copepoda Cyclopoida ; animal distribution ; Pacific Fauna ; Brackish water crustaceans
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    Topics: Biology
    Notes: Abstract Halicyclops hurlberti, a new species of cyclopoid copepod, is described from San Diego, California. Specimens identified by C.D. Marsh as H. aequoreus kept in the US Museum of Natural History were checked and placed in the species H. cf. clarkei Herbst and H. fosteri M. S. Wilson. The description of these two species is being emended.
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    Hydrobiologia 223 (1991), S. 47-68 
    ISSN: 1573-5117
    Keywords: Chile ; amphipoda ; gammaridea ; taxonomy ; catalogue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The taxonomy of gammaridean amphipods is poorly known in Chile. The lack of literature has discouraged investigation of this group, which has been overlooked for years. This has led to the exclusion of amphipods from biological and ecological studies done in our country. I present here a preliminary report on the actual state of the group with reference mainly to its taxonomy, ecological studies and a species catalogue. I have only included species from continental Chile north of 56 °S, Juan Fernandez Archipelago and Isla de Pascua. Species from Chilean Subantarctic and Antarctic waters are excluded, because they are well covered by other authors. There are 168 known for Chile, 36 of them undescribed or with their status not clear. This report is based on a revision of the species recorded for Chile, analysis of samples from the Chilean coast and the work of ecologists who are using the group as material for study.
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  • 62
    ISSN: 1573-5117
    Keywords: Turbellaria ; Tricladida ; Dugesia ; karyology ; taxonomy ; Japan
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    Topics: Biology
    Notes: Abstract The karyotypes of Dugesia japonica from the southern part of the Southwest Islands of Japan (the Nansei Shotô) include diploidy, triploidy, mixoploidy, and mixoaneuploidy. Animals having karyotypes based on n = 8 were found on Okinawa Island, Ishigaki Island, Iriomote Island, and Yonaguni Island, while animals having karyotypes based on n = 7 were found on Okinawa Island, Miyako Island, and Ishigaki Island. Toward the northern end of this island chain, at Tanegashima Island, Yakushima Island, and Amami-Ôshima Island, karyotypes based on n = 8 occurred; and on one of these, Tanegashima Island, n = 7 also occurred. Our data provide further support of the karyotypical distinction between the two subspecies of D. japonica: D. j. japonica has karyotypes based on n = 8 and D. j. ryukyuensis has karyotypes based on n = 7. Taking into consideration the geological history of the Southwest Islands and the ties of their faunas to those of adjacent areas, we can explain the current geographical distribution of the two subspecies in these islands as the result of two separate invasions by D. japonica, one in the Miocene and one after the early Quaternary.
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    Hydrobiologia 227 (1991), S. 349-352 
    ISSN: 1573-5117
    Keywords: Tricladida ; Terricola ; taxonomy ; methodology ; microtechnique
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    Topics: Biology
    Notes: Abstract Traditionally used methods for collecting and preserving terrestrial flatworms have proved deficient in various respects. Comparison of methods for preparing these animals for taxonomic study has shown that preservation of morphological characters can best be achieved using formaldehyde-calcium-cobalt fixative and subsequent storage in an aqueous solution of propylene phenoxetol plus propylene glycol and that the best-lasting histological preparations make use of light-fast, oxidation-resistant dyes and synthetic mounting media with an anti-oxidant.
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    Hydrobiologia 216-217 (1991), S. 691-697 
    ISSN: 1573-5117
    Keywords: nematocysts ; sea anemones ; Anthozoa ; taxonomy ; identification ; nomenclature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A brief historical review of nematocyst terminology is given and three nomenclatural problems are discussed. It is proposed to combine the terms initiated by Weill (1934) with those of Schmidt (1969). A new mesobasic grade, intermediate between microbasic and macrobasic is proposed for amastigophores and p-mastigophores possessing a short Faltstück. A more liberal interpretation of Weill's (1934) terminology for nematocysts than that proposed by Cutress (1955) is suggested in respect of microbasic amastigophores and p-mastigophores. Basitrichs and b-mastigophores continue to be recognized as separate categories.
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    Hydrobiologia 220 (1991), S. 167-178 
    ISSN: 1573-5117
    Keywords: heteronemertea ; freshwater ; Pearl River ; taxonomy ; Amniclineus zhujiangensis gen. et sp. nov.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new genus and species of freshwater heteronemertean, Amniclineus zhujiangensis, from the Zhujiang (Pearl River), People's Republic of China, is described and illustrated. The species is placed in the family Lineidae along with the existing freshwater heteronemertean taxa, with which its anatomy is compared.
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    Hydrobiologia 225 (1991), S. 45-62 
    ISSN: 1573-5117
    Keywords: Cladocera ; taxonomy ; distribution ; Venezuela
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    Topics: Biology
    Notes: Abstract 24 cladoceran species were found in collections from several fresh waterbodies, including environmental samples and gut contents of small micro-characid fishes from Mantecal (Apure state). Nine of these were new records for Venezuela and 18 for the Mantecal area. Brief descriptions of locations and species, including range-distribution, are given.
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    Hydrobiologia 225 (1991), S. 23-35 
    ISSN: 1573-5117
    Keywords: cladocera ; Diaphanosoma ; biogeography ; taxonomy ; ecology ; Spain
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    Topics: Biology
    Notes: Abstract During a 1987–88 extensive limnological study of Spanish reservoirs, euplanktonic cladocerans were sampled all around the country. Two species of Diaphanosoma Fischer, 1850 were recorded, viz D. mongolianum Uéno, 1938 and D. brachyurum (Liévin, 1848). Morphological descriptions of both species are presented, especially of the thoracic limbs, together with notes on their ecology. Both species present a clear allopatric distribution, D. brachyurum inhabiting waters with a low Total Dissolved Salt (TDS) content, which equilibrated relative ionic composition, characteristic of a narrow strip in the northern part of the Iberian Peninsula; on the contrary, D. mongolianum inhabits waters with high TDS values and high content of sulphate or chloride, characteristic of the central and southern regions.
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    Hydrobiologia 225 (1991), S. 9-22 
    ISSN: 1573-5117
    Keywords: Crustacea ; Cladocera ; Daphniidae ; Daphnia ; Ctenodaphnia ; taxonomy ; biology
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    Topics: Biology
    Notes: Abstract European populations of Daphnia similis Claus have been compared with populations from tropical Asia. Daphnia similoides n. sp. from tropical Asia was described as the sibling species of D. similis. The female has characteristic neonate, postabdomen, head, and ephippium. The male has characteristic rostrum, antennules, and the distalmost part of the postabdomen. The D. similis group was compared with D. carinata s. str. Australian populations.
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  • 69
    ISSN: 1573-5117
    Keywords: Turbellaria ; Tricladida ; Bipalium ; karyology ; taxonomy ; Japan
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    Topics: Biology
    Notes: Abstract We have employed a new scale for characterizing chromosomal forms in the karyotypes of four species of Bipalium from five localities in Japan. Specimens of Bipalium nobile Kawakatsu et Makino, 1982, from Yokohama had a diploid chromosome number of 2x = 10 (2m + 2sm + 2sm + st & sm + 2sm); specimens of the same species from Toyonaka had this number as well but with slightly different chromosomal form (2m + 2sm + sm & st + 2st + m & sm). An undescribed species from Sanjô, Bipalium sp. 2, with two dorsal stripes and a yellow head crescent, had 2x = 10 (2m + 2sm + 2sm + 2sm + 2m); and another undescribed species from Chichijima Island, Bipalium sp. 3, with five dorsal stripes, had 2x = 10 (2m + 2sm + 2sm + 2sm + 2m). A non-sexual bipaliid tentatively identified as Bipalium kewense Moseley, 1878, from Chichijima Island had 2x = 18 (2m + 2m + 2m + 2sm + 2st + 2sm + 2sm + 2sm + 2sm).
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    Antonie van Leeuwenhoek 59 (1991), S. 77-80 
    ISSN: 1572-9699
    Keywords: Lipomycetaceae ; micropores ; taxonomy ; yeasts ; Zygozyma
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    Topics: Biology
    Notes: Abstract Septal micropores or plasmadesmal canals have been observed in two species of the lipomycetaceous genus Zygozyma. The presence of these canals is considered as further evidence for the connexion between the Lipomycetaceae and the Dipodascaceae. The genus Zygozyma has been emended.
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    Antonie van Leeuwenhoek 59 (1991), S. 177-181 
    ISSN: 1572-9699
    Keywords: Cryptococcus yarrowii ; yeasts ; taxonomy
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    Topics: Biology
    Notes: Abstract A novel species of the basidiomycetous genusCryptococcus is described asCr. yarrowii based on the study of an isolate from a decayed mushroom collected in Portugal. DNA-DNA homology with the type strain of the phenotypically similar speciesCr. albidus was 10±2%.
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  • 72
    ISSN: 1572-9699
    Keywords: Fellomyces horovitziae ; basidiomycetous yeasts ; taxonomy
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    Notes: Abstract A new species of the genusFellomyces, F. horovitziae, was isolated from aXenasmatella basidiocarp. It differs from other accepted species in its carbon assimilation pattern, mol% G+C and low DNA-DNA homology. The delimiting characters are discussed and a key to the genus is provided.
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    Antonie van Leeuwenhoek 60 (1991), S. 35-42 
    ISSN: 1572-9699
    Keywords: black yeasts ; Aureobasidium ; Hormonema ; Hortaea ; Ramichloridium ; Zasmidium ; karyology ; taxonomy
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    Notes: Abstract Mycelial development of seventy-three strains of black yeasts and related fungi were studied, and numbers of nuclei per hyphal cell were counted. Two main patterns were apparent in expanding hyphae, viz. (1) uninucleate expanding hyphal cells, septum formation strictly following mitosis, and (2) multinucleate, branched, aseptate hyphal tips, septa being formed in a later stage, leading to oligo- or uninucleate mature cells. Characteristic genera in the two groups areExophiala andAureobasidium, respectively. InZasmidium and in someRamichloridium species all mycelial cells are oligonucleate. The character is indicative for relationships at the family level in black yeasts.
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    Antonie van Leeuwenhoek 59 (1991), S. 125-127 
    ISSN: 1572-9699
    Keywords: Taxonomy ; Williopsis Salicorniae ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four strains of an undescribed species of the genus Williopsis were isolated from brackish water. A description of the new species, Williopsis salicorniae (type strain, CBS 8071, NRRL Y-12834), is given.
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  • 75
    ISSN: 1572-9699
    Keywords: yeast ; systematics ; taxonomy ; proton symport ; sugar
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    Notes: Abstract The occurrence of proton symport mechanisms for the transport of glucose, galactose, fructose, raffinose and sucrose in 21 yeast strains representing the species of the genusKluyveromyces was surveyed. Proton symport of one or more sugars occurred in 57% of the strains. Similarly, all the sugars investigated were transported by symports by several strains. Symport systems for non-utilisable sugars were rare. Starvation of cells frequently resulted in the appearance of a symport absent in non-starved glucose-grown cells, indicating that repression of proton symports by glucose and subsequent derepression by starvation is a general phenomenon in members ofKluyveromyces. The addition of a sugar to cell suspensions resulted in acidification in 80% of cases, indicating the activity of a membrane-bound ATPase. Acidification was also observed with a number of sugars that cannot be utilised by the particular species. Interesting correlations between the number of proton symports and the abundance of other phenotypic characteristics in members of the genus emerged. Most members of the infertile group of species showing an increase in the number of small chromosomes, inability to produce well-developed pseudomycelium, linoleic and linolenic acid, a decrease in the number of carbon compounds utilised and inability to utilise ethylamine also had no proton symports, whereas most members of the interfertile species produced one or more proton symports. It was concluded that the distribution of the number of proton symports amongstKluyveromyces species coincided with that of other positive characteristics and may therefore be of taxonomic value.
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  • 76
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    Keywords: Cnidaria ; Halocordyle ; indicator species ; taxonomy ; Brazil ; intraspecific variation ; phenotypic response ; cnidome ; biometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rediscovery of Halocardyle fragilis Vannucci, of which the type material is lost, led us to consider it a variety of Halocardyle disticha (Goldfuss) that occurs in calm waters on soft bottoms. The typical H. disticha is open feather-shaped, with branching in one plane, while H. fragilis is bushy, much larger, with branching in many planes. The different habit of H. disticha is probably due to environmental conditions. The bushy and pinnate forms are considered extremes of a range of morphological variation.
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    Hydrobiologia 216-217 (1991), S. 453-461 
    ISSN: 1573-5117
    Keywords: Actiniidae ; planulae ; taxonomy ; zooxanthellae ; diet ; feeding ; predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Entacmaea medusivora sp. nov., a member of the family Actiniidae, inhabits Jellyfish Lake in Palau, western Caroline Islands, and eats the rhizostome jellyfish Mastigias papua. The anemone is azooxanthellate, despite its jellyfish prey containing symbiotic algae. Well fed anemones released ciliated planula-like larvae in the laboratory when maintained at more than 30 °C. It could not be determined whether the larvae, which usually settled around the parent within 24 h of release, were produced sexually or asexually.
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  • 78
    ISSN: 1573-5117
    Keywords: Scyphozoa ; Cyanea ; speciation ; biogeography ; taxonomy
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    Topics: Biology
    Notes: Abstract Two populations of Cyanea, one in the Niantic River estuary and the other in the adjacent Niantic Bay portion of Long Island Sound, were studied for more than a decade. The estuary and the bay are connected by a narrow channel: this and hydrographic features constrain transport between them. Specimens from each site exhibit morphological and seasonal differences comparable to those which distinguish C. capillata from C. lamarckii in European waters. Reproducing River medusae never cooccurred with reproducing Bay medusae. Estuarine jellyfish are sometimes found in the Bay, but reproducing individuals have not been seen there. Reproductively mature Bay jellyfish occasionally appear in the River, but benthic samples show that they do not deposit planulae at this site and thus do not contribute to the next generation of medusae in the River. Such differences suggest an absence of gene flow between these two populations, indicating that the River medusae and Bay medusae might be separate species.
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