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  • Yeast  (162)
  • Drosophila  (150)
  • Springer  (311)
  • American Chemical Society
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2015-2019
  • 2005-2009
  • 1985-1989  (311)
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Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 315-323 
    ISSN: 1476-5535
    Keywords: Sugar uptake ; Yeast ; Brewer's wort
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary When glucose and fructose are fermented separately, the uptake profiles indicate that both sugars are utilized at similar rates. However, when fermentations are conducted in media containing an equal concentration of glucose and fructose, glucose is utilized at approximately twice the rate of fructose. The preferential uptake of glucose also occurred when sucrose, which was first rapidly hydrolyzed into glucose and fructose by the action of the enzyme invertase, was employed as a substrate. Similar results were observed in the fermentation of brewer's wort and wort containing 30% sucrose and 30% glucose as adjuncts. In addition, the high levels of glucose in the wort exerted severe catabolite repression on maltose utilization in theSaccharmyces uvarum (carlsbergensis) brewing strain. Kinetic analysis of glucose and fructose uptake inSaccharomyces cerevisiae revealed aK m of 1.6 mM for glucose and 20 mM for fructose. Thus, the yeast strain has a higher affinity for glucose than fructose. Growth on glucose or fructose had no repressible effect on the uptake of either sugar. In addition, glucose inhibited fructose uptake by 60% and likewise fructose inhibited, glucose uptake by 40%. These results indicate that glucose and fructose share the same membrane transport components.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of industrial microbiology and biotechnology 4 (1989), S. 49-53 
    ISSN: 1476-5535
    Keywords: l-Phenylacetyl carbinol ; Saccharomyces cerevisiae ; Yeast ; Benzaldehyde ; Biotransformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The rate of production ofl-phenylacetyl carbinol bySaccharomyces cerevisiae in reaction mixtures containing benzaldehyde with sucrose or pyruvate as cosubstrate was investigated in short 1 h incubations. The effect of yeast dose rate, sucrose and benzaldehyde concentration and pH on the rate of reaction was determined. Maximum biotransformation rates were obtained with concentrations of benzaldehyde, sucrose and yeast of 6 g, 40 g and 60 g/l, respectively. Negligible biotransformation rates were observed at a concentration of 8 g/l benzaldehyde. The reaction had a pH optimum of 4.0–4.5. Rates of bioconversion of benzaldehyde and selected substituted aromatic aldehydes using both sucrose and sodium pyruvate as cosubstrate were compared. The rate of aromatic alcohol production was much higher when sucrose was used rather than pyruvate.o-Tolualdehyde and 1-chlorobenzaldehyde were poor substrates for aromatic carbinol formation although the latter produced significant aromatic alcohol in sucrose-containing media. Yields of 2.74 and 3.80 g/l phenylacetyl carbinol were produced from sucrose and pyruvate, respectively, in a 1 h reaction period.
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  • 3
    ISSN: 1572-8773
    Keywords: Manganese ; Electron spin resonance ; Superoxide dismutase ; Saccharomyces cerevisiae ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Manganese accumulation was studied by room-temperature electron spin resonance (ESR) spectroscopy inSaccharomyces cerevisiae grown in the presence of increasing amounts of MnSO4. Mn2+ retention was nearly linear in intact cells for fractions related to both low-molecular-mass and macromolecular complexes (‘free’ and ‘bound’ Mn2+, respectively). A deviation from linearity was observed in cell extracts between the control value and 0.1 mM Mn2+, indicating more efficient accumulation at low Mn2+ concentrations. The difference in slopes between the two straight lines describing Mn2+ retention at concentrations lower and higher than 0.1 mM, respectively, was quite large for the free Mn2+ fraction. Furthermore it was unaffected by subsequent dialyses of the extracts, showing stable retention in the form of low-molecular-mass complexes. In contrast, the slope of the line describing retention of ‘bound’ Mn2+ at concentrations higher than 0.1 mM became less steep after subsequent dialyses of the cell extracts. This result indicates that the macromolecule-bound Mn2+ was essentially associated with particulate structures. In contrast to Cu2+, Mn2+ had no effect on the major enzyme activities involved in oxygen metabolism except for a slight increase of cyanide-resistant Mn-superoxide dismutase activity, due to dialyzable Mn2+ complexes.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    BioMetals 2 (1989), S. 50-54 
    ISSN: 1572-8773
    Keywords: Cu(I)8-thionein ; Yeast ; Extracellular ; Circular dichroism ; Fluorescence ; Electronic absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The release of intact CU(I)8-thionein from copper-resistant copper-loaded yeast cells, strain X 2180-1Aa, has been shown. This copper(I)-thiolate-rich protein was characterized and compared with the chemical and physicochemical properties of intracellular yeast Cu-thionein. The same molecular mass and stoichiometry of 8 mol copper atoms/mol protein was found. No detectable difference between the Cu-thioneins was seen in luminescence emission, electronic absorption in the ultraviolet region, chiroptical data or amino acid composition. The importance of stable Cu(I)-thiolates in Cu-thionein as a safe vehicle for transporting copper in a non-reactive manner is confirmed.
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  • 5
    ISSN: 1432-0983
    Keywords: Yeast ; Minichromosomes ; Impaired segregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nondisjunction of artificial yeast minichromosomes (2:0 segregation events) during mitosis is accompanied by the appearance of cells containing more than one copy of the mini-chromosome. A mathematical simulation of this process has demonstrated that under certain conditions, a nondisjunction of the minichromosomes may result in their accumulation in a considerable portion of the cell population. An increase in the copy number of artificial minichromosomes as a result of impaired segregation has been used to develop a new experimental procedure for directly selecting yeast mutants showing an impaired segregation of artificial minichromosomes during mitosis. Four new genes, AMC1, AMC2, AMC3, and AMC4, which control the segregation of artificial minichromosomes in mitosis, have been identified (AMC-3 and AMC4 are mapped to chromosome IV and VII, respectively). Mutations in the genes AMC1–AMC4 also affect the mitotic transmission of natural chromosomes. We suggest that the genes AMC1, AMC2, AMC3, and AMC4 control the segregation of natural chromosomes in yeast.
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  • 6
    ISSN: 1432-0983
    Keywords: Yeast ; Diuron ; Respiration ; Nuclear genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, diuron blocks the respiration pathway at the level of the bc1 complex. Nuclear diuron-resistant mutations which confer in vitro resistance to mitochondrial NADH oxidase have been identified. Five mutations were found to be clustered at two distinct nuclear loci, DIU3 and DIU4. The distance between the two loci was estimated to be about 36.7 cM. These loci do not appear to be centromere-linked and did not show a linkage to any of the genes coding for bc1 complex subunits. DIU3 and DIU4 loci might, therefore, code for other components of the respiratory chain.
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  • 7
    ISSN: 1432-0983
    Keywords: Alcoholic fermentation ; Deletion mutant ; Pyruvate decarboxylase ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We deleted most of the pyruvate decarboxylase structural gene PDC1 from the genome of Saccharomyces cerevisiae. Surprisingly, mutants carrying this deletion allele showed a completely different phenotype than previously described point mutations. They were able to ferment glucose and their specific pyruvate decarboxylase activity was only reduced to 45% of the wild type level. Northern blot analysis revealed that a sequence in the yeast genome homologous to PDC1 and formerly designated as a possible pseudogene is expressed and may code for a different but closely related pyruvate decarboxylase. The products of the two PDC genes seem to form hybrid oligomers, however both homooligomers have enzyme activity. Thus, the product of the PDC1 gene is not absolutely neccessary for glucose fermentation in yeast.
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  • 8
    ISSN: 1432-0983
    Keywords: Yeast ; 2μm FRT duplication ; Intrachromosomal recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A YEp chimaeric plasmid carrying SMR1 and URA3 genetic markers was integrated into chromosome XIII at the ilv2-Δ1 locus in a [cir°] background. The 1.5 kb BglII deletion of ilv2-Δ1 allowed the clear identification of an integrant structure which consisted of a direct tandem duplication (TD) of the chimaeric plasmid. Within the integrant structure, a single copy of the plasmid sequence was flanked by a direct duplication of the 2μm site-specific recombinase (FLP) recognition target (FRT). Isogenic [cir°] and [cir +] diploids formed by crossing the [cir°] TD strain to complementary haploids were analyzed for plasmid marker loss and chromosomal DNA alterations in the presence and absence of selection pressure for the URA3 and SMR1 plasmid borne markers. [cir°] diploids showed no plasmid marker loss and maintained the TD structure. In the absence of selection pressure, the [cir +] diploid underwent FLP-FRT mediated unequal interchromatid recombination, resulting in the breakage-fusion-bridge cycle and homozygotization of chromosome XIII (Rank et al. 1988). Maintenance of selection pressure for the centromere distal plasmid URA3 marker selected against FLP-FRT interchromatid recombinants so that the effects of site specific recombinase on intrachromatid recombination could be evaluated. Intrachromatid recombination at the directly duplicated FRT sites of the TD structure resulted in the loss of a diagnostic internal fragment. These results show that in the presence of FLP, FRT sites separated by up to 13.3 kb of chromosomal DNA function as substrates for intra and interchromatid recombination.
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  • 9
    ISSN: 1432-0983
    Keywords: Yeast ; Diuron ; Nuclear, mitochondrial mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, diuron blocks the respiratory pathway at the level of the bc1 complex. Two mitochondrially inherited loci, DIU1 and DIU2, located in the cytochrome b gene, and two nuclearly inherited loci, DIU3 and DIU4, have previously been identified. The present work genetically characterizes two double mutants. One mutant, Diu-217, carries two nuclearly inherited mutations, diu3-217a and diu-217b; the second mutant, Diu-783, carries the previously described nuclear mutation diu3-783 and a mitochondrial mutation diu2-783. Each mutation, independent of its location, exhibits a weak diuron resistance. The joint expression of two or three mutations leads to a cumulative or a cooperative enhanced diuron-resistant phenotype.
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  • 10
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondrial frameshift suppressor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A polypeptide chain-terminating mutation (M5631) previously has been shown to be a +1T insertion in the yeast mitochondrial gene oxi1, coding for subunit II of the cytochrome c oxidase. A spontaneously arisen frameshift suppressor (mfs-1) that is mitochondrially inherited suppresses this mutation to a considerable extent. The suppressor mutation was mapped by genetic and molecular analyses in the mitochondrial tRNASer-var1 region of the mitochondrial genome of the yeast S. cerevisiae. Genetic analyses show that the suppressor mfs-1 does not suppress other known mitochondrial frameshift mutations, or missense and nonsense mutations.
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  • 11
    ISSN: 1432-0983
    Keywords: Yeast ; Ribosomal protein gene ; Transcription activation ; Mutation ; Methylation interference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Most ribosomal protein (rp-)genes in yeast are preceded by conserved sequence motifs that act as upstream transcription-activating sites (RPG box). These sequence elements have previously been shown to represent specific binding sites for a protein factor, TUF. Comparison of the various nucleotide elements identified so far indicates a remarkably high degree of variation in the respective sequences. On the other hand, a methylation interference study performed with one RPG box revealed close contact points with the TUF protein along the entire sequence. To investigate the sequence requirements of the RPG box, we inserted synthetic oligonucleotides that differed from the general consensus sequence ACACCCATACATTT at single positions into a deletion mutant of the L25 promoter that lacked its natural RPG elements. Transcription activity was estimated by Northern analyses of the cellular level of L25-galK hybrid transcripts. The results show that in the 3′ part of this sequence element single substitutions are allowed at all positions, in the 5′ part, however, the nucleotide requirements appear to be more stringent. In particular, the invariant C at position 5 of the consensus sequence is absolutely necessary for its enhancer function.
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  • 12
    ISSN: 1432-0983
    Keywords: Yeast ; oxi3 gene ; Petite genome ; Frameshift mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sequence analysis was used to define the repeat unit that constitutes the mitochondrial genome of a petite (rho −) mutant of the yeast Saccharomyces cerevisiae. This mutant has retained and amplified in tandem a 2,547 by segment encompassing the second exon of the oxi3 gene excised from wild-type mtDNA between two direct repeats of 11 nucleotides. The identity of the mtDNA segment retained in this petite has recently been questioned (van der Veen et al., 1988). The results presented here confirm the identity of this mtDNA segment to be that determined previously by restriction mapping (Carignani et al., 1983).
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  • 13
    ISSN: 1432-0983
    Keywords: Yeast ; Transcription ; RNA polymerase I ; Enhancer ; DNA-binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using the gel retardation assay we have identified a protein that can specifically bind to a site within the enhancer of the 37S pre-ribosomal RNA operon in yeast, as well as to a site 210 by upstream of the site of transcription initiation of this operon. This protein (RBP1) has been partially purified by means of heparin-agarose chromatography and protects 20 by in the rDNA enhancer, and 25 by in the initiation region, against DNase I in an in vitro footprinting assay. In vivo footprinting studies using methylation of intact yeast cells with dimethylsulphate, indicate that the same binding sites are occupied in vivo as well. Deletions that abolish binding of RBP1 to the enhancer in vitro, as well as linker insertions into the RBP1 binding site in the initiation region that strongly diminish in vitro binding of RBP1, have no effect whatsoever on the enhancement of rDNA transcription in vivo. This was studied by deletion/mutation of the RBP1 binding site in vitro in an artificial ribosomal minigene and measuring the effect on the minigene transcription in vivo in yeast cells, transformed with the deleted/mutated minigenes. It can therefore be concluded that binding of RBP1 is not an important parameter in the functioning of the rDNA enhancer in yeast. Using the same minigene system we also show that RBP1 is not involved in termination of RNA polymerase I (PolI) transcription at the main terminator T2.
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  • 14
    ISSN: 1432-0983
    Keywords: Yeast ; Saccharomyces cerevisiae ; Nonsense suppression ; Omnipotent suppressors ; Gene mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ten dominant omnipotent suppressors of Saccharomyces cerevisiae, which were previously shown to be different from SUP46, have been examined. Nine are mapped in a region between lys5 and cyh2 on the left arm of chromosome VII. These suppressors, like SUP46, manifest sensitivity to increased temperature and the antibiotics paromomycin and hygromycin B. In addition, they have an identical action spectrum. These results strongly suggest that they are allelic to each other and they are designated SUP138. The tenth is mapped to a position between his1 and arg6 on the right arm of chromosome V. This suppressor, named SUP139, does not manifest temperature sensitivity nor antibiotic sensitivity. SUP139 and SUP138, which are clearly distinguished by means of action spectrum, act on much fewer nonsense mutations than SUP46. It is now clear that dominant omnipotent suppressors arising at a single locus are homogeneous and that their efficiency is locus-dependent. The order of efficiency is SUP46〉SUP138〉SUP139.
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  • 15
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    Current genetics 16 (1989), S. 339-346 
    ISSN: 1432-0983
    Keywords: Yeast ; Transformation ; ss carrier DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A method, using LiAc to yield competent cells, is described that increased the efficiency of genetic transformation of intact cells of Saccharomyces cerevisiae to more than 1 × 105 transformants per microgram of vector DNA and to 1.5% transformants per viable cell. The use of single stranded, or heat denaturated double stranded, nucleic acids as carrier resulted in about a 100 fold higher frequency of transformation with plasmids containing the 2μm origin of replication. Single stranded DNA seems to be responsible for the effect since M13 single stranded DNA, as well as RNA, was effective. Boiled carrier DNA did not yield any increased transformation efficiency using spheroplast formation to induce DNA uptake, indicating a difference in the mechanism of transformation with the two methods.
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  • 16
    ISSN: 1432-0983
    Keywords: Platinum compounds ; Yeast ; Repair mutants ; Interstrand cross-links ; DNA degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Four haploid yeast strains differing in proficiency for DNA repair were treated with cis- or transDDP. The wild type was least sensitive while the excision-deficient mutants rad1, rad2 and snm1exhibited higher sensitivities to either platinum compound. In all four strains tested cisDDP showed a two- to five-fold higher cytotoxicity than equimolar concentrations of transDDP. DNA interstrand cross-linking was caused by both agents in all strains. However, transDDP introduced more DNA cross-links at exposure times up to 6 h while cisDDP was the more active cross-linking agent at longer times. There was no clear-cut correlation of the number of DNA interstrand cross-links with survival. Formaldehyde-treated cells showed DNA with lower buoyant density due to proteinase K sensitive DNA-protein cross-linking; this effect was not observed after treatment with either platinum compound. Post-treatment incubation of wild-type cells exposed to cisDDP led to degradation of DNA by single and double-strand breaks, parallel with further increase of DNA interstrand cross-linking. DNA from transDDP-treated cells did not show extensive degradation although interstrand cross-links were lost during liquid holding.
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  • 17
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    Current genetics 16 (1989), S. 347-350 
    ISSN: 1432-0983
    Keywords: Yeast ; 7SL RNA ; Yarrowia lipolytica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have identified an abundant cytoplasmic 7S RNA in crude extracts of the yeast Yarrowia lipolytica. A cDNA probe was prepared from this RNA and used to screen a genomic library. The DNA sequence of a positive clone was determined and the end positions of the 7S RNA gene established by comparison with the sequence of the extremities of 7S RNA. This gene, designated SCR2, encodes a 270-nucleotide RNA that can be folded into a secondary structure similar to that of 7SL RNAs. This RNA is 94.4% homologous to a previously identified 7S RNA from this yeast, but is encoded by a separate gene with highly divergent flanking sequences.
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  • 18
    ISSN: 1432-0983
    Keywords: Yeast ; Repair ; Complementation ; Saccharomyces cerevisiae ; Schizosaccharomyces pombe ; Gene cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two Saccharomyces cerevisiae genes necessary for excision repair of UV damage in DNA, RAD1 and RAD2, were introduced individually, on a yeast shuttle vector, into seven Schizosaccharomyces pombe mutants — rads1, 2, 5, 13, 15,16 and 17. The presence of the cloned RAD1 gene did not affect survival of any of the S. pombe mutants. The RAD2 gene increased survival of S. pombe rad13 to near the wild-type level after UV irradiation and had no effect on any of the other mutants tested. S. pombe rad13 mutants are somewhat defective in removal of pyrimidine dimers so complementation by the S. cerevisiae RAD2 gene suggests that the genes may code for equivalent proteins in the two yeasts.
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  • 19
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    Current genetics 15 (1989), S. 99-106 
    ISSN: 1432-0983
    Keywords: Yeast ; Isoleucyl-tRNA synthetase ; Isoleucine ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The isoleucyl-tRNA synthetase gene (ILS1) from the yeast Saccharomyces cerevisiae was cloned and sequenced. This gene was initially cloned because it cross-hybridizated to what is now presumed to be the isoleucyl-tRNA synthetase gene (cupC) from the protozoan Tetrahymena hhermophila. The ILS1 gene was determined to be 1,072 amino acids in length. A comparison with a recently published sequence of ILS1 1 from another laboratory (Englisch et al. 1987) was made and differences noted. Two promoter elements were detected, one for general amino acid control and one for constitutive transcription. A heat shock protein (hsp70) gene (probably SSA3) was found 237 by upstream from the ILS1 translation start site. The ILS1 amino acid sequence was compared to isoleucyl-tRNA synthetases from other organisms, as well as to valyl-, leucyl- and methionyl-tRNA synthetases. Regions of conservation between these enzymes were found.
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  • 20
    ISSN: 1432-0983
    Keywords: PDC3 ; Pyruvate decarboxylase ; Subunits ; Yeast ; Cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Biochemical evidence that pyruvate decarboxylase in S. cerevisiae might be constituted from two independently encoded subunits led us to question genetic evidence for a single structural gene. The main evidence for this was that three “structural” mutations appeared to be alleles of the same gene, PDC1 (Schmitt and Zimmermann 1982). We report that one of these mutations (pdcl-30) is not allelic either to other pdc1 alleles or to pdc2 mutations and therefore is has been renamed pdc3-30 thus identifying a new gene, PDC3. We have cloned the PDC3 gene, it represents a unique sequence in the genome and targeted integration shows tight linkage to the PDC3 locus. However, the size, abundance and regulation of the PDC3 transcript suggest that it does not encode a second structural gene. Possible functions for the PDC3 gene product are discussed.
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  • 21
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    Current genetics 16 (1989), S. 21-25 
    ISSN: 1432-0983
    Keywords: Yeast ; Vectors ; Stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have constructed a set of hybrid yeast Escherichia coli vectors which utilise the site specific recombination function of the Saccharomyces cerevisiae 2 μm plasmid to completely eliminate the bacterial moiety upon introduction into yeast. A number of these plasmids have been shown to exhibit high inheritable stability in both laboratory and industrial strains during non-selective growth. These plasmids are beneficial for the genetic modification of industrial yeast, particularly those used in the production of food and beverages, and are of benefit in the study of plasmid maintenance and heterologous gene expression.
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  • 22
    ISSN: 1432-0983
    Keywords: Yeast ; Chromosome organization ; Acid phosphatase ; Telomere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 17 kb region from near the right end of chromosome I of Saccharomyces cerevisiae was isolated on recombinant λ bacteriophages. This region contained the PH011 gene which was located only 3.4 kb from the right end of the chromosome. We found that this region also was repeated approximately 13 kb from the end of the chromosome VIII DNA molecule. The chromosome VIII sequence appears to be a previously unnamed acid phosphatase gene that we propose to call PH012. Thus, similar to the repeated SUC, MAL, X and Y' sequences, some members of the repeated acid phosphatase gene family also appear near the termini of yeast chromosomes.
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  • 23
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondria ; Intron splicing ; RNA maturase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the expression and function of the intron-encoded bI4 maturase when frame-shift mutations in the upstream exon alter the translational process. By constructing secondary cis-acting mutations within the b14 intron, we observed (1) that the bI4 maturase is still translated in the presence of the upstream mutation, albeit in very low amounts, and (2) that the limited amounts of bI4 maturase made under these conditions is no longer able to promote the splicing process of the aI4 intron. These observations, which further strengthen the maturase model, strongly suggest that bI4 maturase acts sequentially on the bI4 intron and then on the aI4 intron.
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  • 24
    ISSN: 1432-0983
    Keywords: Telomere Binding Activity (TBA) ; Yeast ; Telomeric binding sites ; RAP1 gene product
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Telomere Binding Activity (TBA), an abundant protein from Saccharomyces cerevisiae, was identified by its ability to bind to telomeric poly(C1–3A) sequence motifs. The substrate specificity of TBA has been analyzed in order to determine whether the activity binds to a unique structure assumed by the irregularly repeating telomeric sequences or whether the activity recognizes and binds to subset of specific sequences found within the telomere repeat tracts. Deletion analysis and DNase I protection assays demonstrate that TBA binds specifically to two poly(C1–3A) sequences that differ by one nucleotide. The methylation of four guanine residues, located at identical relative positions within these two binding sequences, interferes with TBA binding to the substrates. A synthetic olignucleotide containing a single TBA binding site can function as a TBA binding substrate. The TBA binding site shares homology with the binding sites reported for the Repressor/Activator Protein 1 (RAP1), Translation Upshift Factor (TUF) and General Regulatory Factor (GRFI) transcription factors, and TBA binds directly to RAP1/TUF/GRFI substrate sequences. Yeast TBA preparations and the RAP1 gene product expressed in E. coli cells are both similarly sensitive to in vitro protease digestion. Affinity-purified TBA extracts include a protein indistinguishable from RAP1 in binding specificity, size, and antigenicity. The binding affinity of TBA for the two telomeric poly(C1–3A) binding sites is higher than its affinity for any of the other binding substrates used for its identification. In extracts of yeast spheroplasts prepared by incubation of yeast cells with Zymolyase, an altered, proteolyzed form, of TBA (TBA-S) is present. TBA-S has a faster mobility in gel retardation assays and SDS-PAGE gels, yet it retains the DNA binding properties of standard TBA preparations: it binds to RAP1/TUF/GRFI substrates with the same relative binding affinity and protects poly(C1–3A) tracts from DNase I digestion with a “footprint” identical to that of standard TBA preparations.
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  • 25
    ISSN: 1432-0983
    Keywords: Yeast ; DNA methylation ; DNA methyltransferase ; rad mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary DNA methyltransferase activity is not normally found in yeast. To investigate the response of Saccharomyces cerevisiae to the presence of methylated bases, we introduced the Bacillus subtilis SPR phage DNA-[cytosine-5] methyltransferase gene on the shuttle vector, YEp51. The methyltransferase gene was functionally expressed in yeast under the control of the inducible yeast GAL10 promoter. Following induction we observed a time-dependent methylation of yeast DNA in RAD + and rad2 mutant strains; the rad2 mutant is defective in excision-repair of UV-induced DNA damage. Analysis of restriction endonuclease digestion patterns revealed that the relative amount of methylated DNA was greater in the excision defective rad2 mutant than in the RAD + strain. These data indicate that the yeast excision-repair system is capable of recognizing and removing m5C residues.
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  • 26
    ISSN: 1432-0983
    Keywords: Yeast ; Mating ; Sexual agglutination ; a-Specific mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seven α-specific mutants specifically defective in sexual agglutinability were isolated. The other α mating functions exhibited by these mutants, designated sag mutants, such as the production of α pheromone and response to a mating pheromone, were normal. While the MATα sag1 cells did not agglutinate with wild-type a cells, the MATα sag1 cells did, indicating that the SAG1 gene is expressed only in α cells. The mutations were semi-dominant and fell into a single complementation group, SAG1, which was mapped near met3 on chromosome X. Complementation analysis showed that sag1 and aga1, the latter being a previously reported α-specific mutation, were mutations in the same gene.
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  • 27
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    Current genetics 15 (1989), S. 385-392 
    ISSN: 1432-0983
    Keywords: Yeast ; Meiosis ; Distributive disjunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Distributive disjunction is defined by first meiotic division segregation of either two nonhomologous chromosomes that lack homologous pairing partners, or of two homologous chromosomes that have failed to undergo crossing-over. In the yeast Saccharomyces cerevisiae, plasmid minichromosomes, synthetic linear chromosomes and a fragment of a real chromosome have been observed to segregate from nonhomologous DNA species at the first meiotic divisions. Suggesting that this organism may have a distributive mechanism for chromosome segregation. However, it is not known whether intact chromosomes also participate in a distributive process. To determine whether intact, full length, S. cerevisiae chromosomes could segregate from nonhomologous chromosomal species, the meiotic behavior of an unpaired intact copy of chromosome I has been analyzed with respect to several centromere-containing circular plasmid minichromosomes. Strains monosomic or trisomic for chromosome I were transformed with centromere plasmids containing either homologous or nonhomologous inserts, sporulated, and analyzed genetically both for the presence of plasmid and for the number of copies of chromosome 1. Each plasmid segregated from an intact unpaired copy of chromosome I at the first meiotic division in a significant majority (63–93%) of the asci examined. These results suggest that intact chromosomes from S. cerevisiae are capable of distributive disjunction.
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  • 28
    ISSN: 1432-0983
    Keywords: Yeast ; Invertase ; Gene expression
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    Notes: Summary Gene SUC4 produced about four fold more invertase activity than did gene SUC5. However, these genes differ in only three positions located in the 5′ non-coding region. The difference in gene expression between SUC4 and SUC5 must be due to the G to A transition (position −497) and/or the C to T transition (position −460) in the upstream activator sequences. The sequence TACAAA present in SUC5 can play the same role than the TATAAA box of SUC4.
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  • 29
    ISSN: 1432-1432
    Keywords: Drosophila ; Foldback element ; Transposable element
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    Topics: Biology
    Notes: Summary Foldback elements are a family of transposable elements described inDrosophila melanogaster. The members of this dispersed repetitive family have terminal inverted repeats that sometimes flank a central region. The inverted repeats of all the family members are homologous. The study of the distribution and conservation of the foldback elements in differentDrosophila species shows that this distribution is different from that of the hybrid dysgenesis systems (PM and IR). Sequences homologous to foldback elements were observed by Southern blots and in situ hybridization in all species of themelanogaster subgroup and in some species of themontium andtakahashii subgroups. The element was probably already present before the radiation of these subgroups. No evidence of horizontal transmission of the foldback element could be observed.
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  • 30
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    Development genes and evolution 198 (1989), S. 227-232 
    ISSN: 1432-041X
    Keywords: Campaniform sensilla ; Drosophila ; Achaete-scute complex ; Cis regulatory sites
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    Topics: Biology
    Notes: Summary We have analysed the role of the achaete-scute gene complex in the development of the pattern of campaniform sensilla on the wing blade of Drosophila. We show that the complete pattern results from the superimposition of two independent subpatterns, one of which depends on the achaete gene and the other on scute. The scute subpattern comprises several clusters of sensilla, most of which seem to require the presence of control regions located upstream of the transcribed region. This is in contrast with the pattern of scute-dependent bristles, most of which depends on control elements located downstream of the transcribed region.
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  • 31
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    Development genes and evolution 198 (1989), S. 65-77 
    ISSN: 1432-041X
    Keywords: Cell communication ; Pattern formation ; Cell differentiation ; trans-regulatory genes ; Drosophila
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    Topics: Biology
    Notes: Summary The effects ofpolyhomeotic (ph) mutants in imaginal cells have been studied in a clonal analysis. Clones of cells, homozygous forph, sort-out after a few divisions, probably as a consequence of modified cell affinities. The dorso-ventral margin of the wing has special characteristics that retard this phenomenon. The formation and exclusion of a clone of 8–16 cells affect the polarity of the wild-type neighbour cells and can provoke pattern triplications. The results suggest that a defect in intercellular communication prevents the wild-type cells from maintaining coordinated positional information. The cells react by regenerative growth, and reorganize into a new pattern. The pleiotropic phenotypes ofph mutants are explained according to a common hypothesis aboutph + function.
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  • 32
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    Development genes and evolution 198 (1989), S. 157-169 
    ISSN: 1432-041X
    Keywords: Distal less ; Limb development ; Drosophila
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    Topics: Biology
    Notes: Summary The development of all of the adult limbs inDrosophila depends upon the activity of theDistal-less gene. We report here the phenotypic characterization of a number of hypomorphicDistal-less alleles which indicates that there is a graded requirement forDistal-less activity in the developing limbs. Previous analysis of genetically mosaic animals indicated that cells in the early primordia of the limb imaginal dises possess a graded proximal-distal positional information which depends on the presence of theDistal-less gene for its expression. Taken together these data suggest thatDistal-less may directly encode the graded positional information that is required to organise the proximal-distal axis of the developing limbs.
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  • 33
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    Development genes and evolution 198 (1989), S. 185-190 
    ISSN: 1432-041X
    Keywords: Drosophila ; Oogenesis ; Follicle cells ; Egg shell ; Ovarian tumor
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    Topics: Biology
    Notes: Summary The developmental potential of the cells of the somatic follicular epithelium (follicle cells) was studied in mutants in which the differentiation of the germ-line cells is blocked at different stages of oogenesis. In two mutants, sn 36a and kelch, nurse cell regression does not occur, yet the follicle cells around the small oocyte continue their normal developmental program and produce an egg shell with micropylar cone and often deformed operculum and respiratory appendages. Neither the influx of nurse cell cytoplasm into the oocyte nor the few follicle cells covering the nurse cells are apparently required for the formation of the egg shell. In the tumor mutant benign gonial cell neoplasm (bgcn) the follicle cells can also differentiate to some extent although the germ-line cells remain morphologically undifferentiated. Vitelline membrane material was synthesized by the follicle cells in some bgcn chambers and in rare cases a columnar epithelium, which resembled morphologically that of wild-type stage-9 follicles, formed around the follicle's posterior end. The normal polarity of the follicular epithelium that is characteristic for mid-vitellogenic stages may, therefore, be established in the absence of morphologically differentiating germ-line cells. However, the tumorous germ-line cells do not constitute a homogeneous cell population since in about 30% of the analyzed follicles a cell cluster at or near the posterior pole can be identified by virtue of its high number of concanavalin A binding sites. This molecular marker reveals an anteroposterior polarity of the tumorous chambers. In follicles mutant for both bgcn and the polarity gene dicephalic the cluster of concanavalin A-stained germ-line cells shifts to more anterior positions in the follicle.
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  • 34
    ISSN: 1432-1939
    Keywords: Drosophila ; Microbial associations ; Resource partitioning
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    Topics: Biology
    Notes: Summary The distributions of five Drosophila species and four components of the microflora have been compared across a total of 48 traps baited with four different fruit and vegetable substrates in two domestic compost heaps in Canberra (Australia). Large and consistent differences are found, both among the Drosophila and among the microbial classes, in their distributions across traps baited with different substrates. Moreover the distribution of each Drosophila species shows a unique set of strong associations with the microbial distributions. Thus the distributions of both D. simulans and D. melanogaster are found to be strongly negatively correlated with the abundance of bacteria while D. simulans is also strongly positively correlated with the titre of fermenter yeasts. D. immigrans is strongly positively correlated both with bacteria and with non-fermenter yeasts. D. hydei is positively correlated with nonfermentery yeasts and D. busckii is negatively correlated with fermenter yeasts. Moulds are the only microbial class not consistently associated with the distribution of any of the Drosophila species. The correlations with the other microbial classes are sufficient to explain the majority of the abundance differences of the Drosophila species among the trap types. It is therefore proposed that the clear partitioning of the fruit resources by the Drosophila is due to their differing primary interactions with the microflora.
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  • 35
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    Journal of comparative physiology 166 (1989), S. 179-187 
    ISSN: 1432-1351
    Keywords: Blowfly ; Drosophila ; Photoreceptor ; Lanthanum ; trp mutant
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    Topics: Biology , Medicine
    Notes: Summary The effect of lanthanum on the light response of blowfly (Calliphora erythrocephala) photoreceptors was studied. The electrophysiological behaviour of the photoreceptors in the presence of La can be summarized as follows: 1. Upon long stimulation the photoreceptors responded with a ‘transient receptor potential’, i.e. the cells depolarized at the onset of the stimulus and then repolarized to (or below) the resting potential. This effect was dependent on stimulus intensity and occurred only at high intensities. During illumination membrane noise was reduced. 2. The light-induced changes in membrane potential were paralleled by changes in membrane resistance. 3. The time course of the receptor response was slowed down. 4. Light adaptation led to an increase in response latency. 5. The recovery of the receptor response after light adaptation was slowed down. 6. The sensitivity of the receptor cells measured by the response to short light stimuli was reduced. In summary, the electrophysiological behaviour of Calliphora photoreceptors in the presence of La was very similar to that of the photoreceptors of the trp (transient receptor potential) mutant of Drosophila melanogaster. This result suggests that La and trp mutation affect the same cellular processes in the photoreceptors.
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  • 36
    ISSN: 1432-072X
    Keywords: Saccharomyces cerevisiae ; Yeast ; Phospholipase B ; Lysophospholipase ; Enzyme inhibition ; AMP ; Unesterified fatty acids
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    Notes: Abstract Divalent cations activate the lysophospholipase and transacylase reactions catalyzed by the same enzymes in the yeast Saccharomyces cerevisiae. The activation was observed at neutral pH, but not at the pH optimum of lysophospholipase/transacylase, near 3.5. Adenine nucleotides, especially AMP and ADP, are strong inhibitors of the same group of enzymes. Half maximal inhibition by AMP was found at a concentration of about 20 μM. The inhibition by nucleotides in low concentrations is enhanced by divalent cations.
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  • 37
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    Archives of microbiology 151 (1989), S. 198-202 
    ISSN: 1432-072X
    Keywords: Sexual agglutination ; Mating ; Saccharomyces cerevisiae ; Yeast
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    Topics: Biology
    Notes: Abstract Genetic regulation of the inducibility of sexual agglutination ability in the yeast Saccharomyces cerevisiae was studied. Detailed analysis of the degree of sexual agglutination was carried out; it showed that a greater number of genes are involved in the regulation of inducible sexual agglutination in strain H1-0 than previously assumed. Although dominancy of inducible phenotype over constitutive was confirmed, the effectiveness of one gene changing the constitutive phenotype to the inducible seemed to be somewhat low. Quantity per cell of agglutination substances responsible for sexual agglutination increased as the agglutination ability became greater.
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  • 38
    ISSN: 1432-072X
    Keywords: d-Xylose fermentation ; Aeration level ; Xylose reductase ; Xylitol dehydrogenase ; Yeast ; Candida shehatae ; Candida tenuis ; Pichia stipitis
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    Topics: Biology
    Notes: Abstract The relationship between the degree of aerobiosis, xylitol production and the initial two key enzymes of d-xylose metabolism were investigated in the yeasts Pichia stipitis, Candida shehatae and C. tenuis. Anoxic conditions severely curtailed growth and retarded ethanol productivity. This, together with the inverse relationship between xylitol accumulation and aeration level, suggested a degree of redox imbalance. The ratios of NADH- to NADPH-linked xylose reductase were similar in all three yeasts and essentially independent of the degree of aerobiosis, and thus did not correlate with their differing capacities for ethanol production, xylitol accumulation or growth under the different conditions of aerobiosis. Under anoxic conditions the enzyme activity of Pichia stipitis decreased significantly, which possibly contributed to its weaker anoxic fermentation of xylose compared to C. shehatae.
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  • 39
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    Archives of microbiology 152 (1989), S. 564-566 
    ISSN: 1432-072X
    Keywords: l-Malate ; Schizosaccharomyces malidevorans ; Yeast
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    Topics: Biology
    Notes: Abstract The yeast Schizosaccharomyces malidevorans utilizes l-malate when grown on glucose as the carbon source. A mutant of this yeast has been isolated which is dependent on the presence of both l-malate and glucose for growth. The mutant utilizes l-malate as rapidly as the wildtype and the utilization of glucose is greatly reduced. Other TCA cycle intermediates do not relieve the malate dependence.
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  • 40
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    Ecological research 4 (1989), S. 209-218 
    ISSN: 1440-1703
    Keywords: Annual life cycle ; Drosophila ; Fungus preference ; Nematode parasitism
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    Topics: Biology
    Notes: Abstract Food preferences and nematode parasitism were studied in natural populations of mycophagousDrosophila in and near Sapporo, northern Japan. Species which preferred fresh mushrooms showed species-specific responses toPleurotus mushrooms:D. pirka bred only onPleurotus cornucopiae, D. trivitata onP. cornucopiae andP. ostreatus, D. trilineata on these twoPleurotus mushrooms and some other mushrooms, whileD. sexvittata bred on a wide variety of mushrooms but seldom onPleurotus mushrooms. Species which preferred decayed mushrooms (D. quadrivittata, D. histrioides, D. testacea and species of thequinaria species-group) showed host preferences different from those of the above species. The rate of parasitism by nematodes was generally higher in species which prefer decayed mushrooms than in species which prefer fresh mushrooms. Among species which prefer fresh mushrooms, onlyD. trilineata was parasitized frequently by nematodes. It was not clear what factors determine the rate of parasitism in these mycophagousDrosophila. D. pirka, D. trivittata andD. trilineata passed through three or four generations per year and entered reproductive diapause in early September in and near Sapporo.
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  • 41
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    Molecular and cellular biochemistry 90 (1989), S. 27-35 
    ISSN: 1573-4919
    Keywords: zerknullt gene ; homeobox protein ; Drosophila ; filter binding
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    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The region upstream from the zerknullt (zen) gene contains three sites that specifically bind the zen protein product of the gene. Evidence for these binding sites was obtained by the filter binding technique and the DNase footprinting technique. The filter binding technique was used to scan various segments of DNA for the presence of possible specific binding sites. Segments that were selectively retained by the filter binding technique invariably contained one or more specific binding sites according to the DNase footprinting technique. Two of the zen protein binding sites were spaced only 30 base pairs apart. These sites could be separated without any loss in their specific binding properties. It is concluded that these two sites function independently in the binding of zen protein.
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  • 42
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    Biochemical genetics 27 (1989), S. 507-520 
    ISSN: 1573-4927
    Keywords: Drosophila ; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) ; glue proteins ; glycosylation
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of theDrosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins inD. n. nasuta andD. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas inD. melanogaster and inD. hydei the fraction is only 32 and 35%, respectively.
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  • 43
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    Biochemical genetics 27 (1989), S. 507-520 
    ISSN: 1573-4927
    Keywords: Drosophila ; sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) ; glue proteins ; glycosylation
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The patterns of protein fractions from total salivary glands and from glue plugs were compared in seven members of theDrosophila nasuta subgroup by the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The glue protein patterns are member specific concerning the numbers and the electrophoretic mobilities of major and minor glue protein fractions. However, the major fractions of all subgroup members could be grouped into five SDS-PAGE domains according to the homologies of their electrophoretic mobilities, prominence of Coomassie blue staining, and PAS reaction. In all subgroup members, major fractions are involved in posttranslational modifications into larger protein molecules of the final glue. Quantitative estimations of the glue proteins inD. n. nasuta andD. n. albomicans reveal that they constitute between 55 and 60% of the total salivary gland proteins, whereas inD. melanogaster and inD. hydei the fraction is only 32 and 35%, respectively.
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  • 44
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    Biochemical genetics 27 (1989), S. 263-277 
    ISSN: 1573-4927
    Keywords: Drosophila ; kinetic plate reader ; enzyme polymorphism
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    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Techniques for performing numerous enzyme kinetic assays with minimum time and effort would be valuable to studies of the evolutionary genetics of metabolic control and the quantitative genetics of determinants of kinetic parameters. Microtiter plate readers have been used for a variety of repetitious analytical techniques, and instruments are available that can take repetitive readings with sufficient speed to perform kinetic assays. The ability of these instruments to assay rapidly the kinetic properties of small samples makes them potentially useful for a number of problems in population genetics. While the ability to handle large numbers of samples is very attractive, the small sample volumes and optical imprecision of microtiter plates result in some sacrifice in accuracy. This paper presents methods for performing kinetic assays on individual field-caughtDrosophila, quantifies the precision of these methods, and characterizes differences amongDrosophila melanogaster andD. simulans from samples caught in California and Pennsylvania. Comparisons between field-caught and laboratory rearedD. melanogaster show that most of the characters are very similar, with the exception of αGPDH, which has a threefold higher mean activity among field-caught flies. The phenotypic correlations are presented with a brief discussion of their relevance to assessing the evolution of metabolic control of these enzymes.
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  • 45
    ISSN: 1573-4927
    Keywords: Drosophila ; aldox-2 ; molybdoenzymes ; sulfite oxidase ; molybdenum ; tungsten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mutation at thealdox-2 locus inDrosophila melanogaster affects the specific activities of four molybdoenzymes differentially during development. Sulfite oxidase activity is normal during late larval and pupal stages but is reduced during early adult stages inaldox-2 organisms. There was complete concordance among the effects ofaldox-2 on sulfite oxidase, aldehyde oxidase, xanthine dehydrogenase, and pyridoxal oxidase, when 38 stocks were analyzed which were derived from single recombination events betweenc andpx, markers which flankaldox-2. Several different biochemical analyses indicate that the active molybdoenzymes present in thealdox-2 strain are normal with respect to size, shape,pH-activity profile,K m , and molecular weight. Significant differences were found between thealdox-2 strain and the OR control strain in their responses to dietary Na2MoO4 and Na2WO4. The mutant strain is much more resistant to the effects of dietary Na2WO4 and much more responsive to the administration of Na2MoO4 than the OR control strain when these effects are quantitated by measurements of molybdoenzyme specific activities. This evidence suggests that thealdox-2 + gene product has a molybdenum binding site which can also bind tungsten and that this site is altered in the mutant strain. The hypothesis presented explains the observed effects of thealdox-2 mutation and relates them to the other mutations reported in this gene-enzyme system.
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  • 46
    ISSN: 1573-3297
    Keywords: Drosophila ; circadian clock ; ultradian oscillations ; disconnected mutant ; visual system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Free-running locomotor activity and eclosion rhythms ofDrosophila melanogaster, mutant at thedisconnected (disco) locus, are substantially different from the wild-type phenotype. Initial periodogram analysis revealed little or no rhythmicity (Dushayet al., 1989). We have reanalyzed the locomotor activity data using high-resolution signal analysis (maximum-entropy spectral analysis, or MESA). These analyses, corroborated by autocorrelograms, uncovered significant residual circadian rhythmicity and strong ultradian rhythms in most of the animals tested. In this regard thedisco mutants are much like flies expressing mutant alleles of theperiod gene, as well as wild-type flies reared throughout life in constant darkness. We hypothesize that light normally triggers the coupling of multiple ultradian oscillators into a functional circadian clock and that this process is disrupted indisco flies as a result of the neural lesion.
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  • 47
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    Theoretical and applied genetics 77 (1989), S. 123-127 
    ISSN: 1432-2242
    Keywords: Inbreeding depression ; Drosophila ; Natural selection
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    Topics: Biology
    Notes: Summary This experiment was designed to study the relationship between rate of inbreeding and observed inbreeding depression of larval viability, adult fecundity and cold shock mortality in Drosophila melanogaster. Rates of inbreeding used were full-sib mating and closed lines of N=4 and N=20. Eight generations of mating in the N=20 lines, three generations in the N=4 lines and one generation of full-sib mating were synchronised to simultaneously produce individuals with an expected level of inbreeding coefficient (F) of approximately 0.25. Inbreeding depression for the three traits was significant at F=0.25. N=20 lines showed significantly less inbreeding depression than full-sib mated lines for larval viability at approximately the same level of F. A similar trend was observed for fecundity. No effect of rate of inbreeding depression was found for cold shock mortality, but this trait was measured with less precision than the other two. Natural selection acting on loci influencing larval viability and fecundity during the process of inbreeding could explain these results. Selection is expected to be more effective with slow rates of inbreeding because there are more generations and greater opportunity for selection to act before F=0.25 is reached. Selection intensities seem to have been different in the three traits measured. Selection was most intense for larval viability, less intense for fecundity and, perhaps, negligible at loci influencing cold shock mortality.
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  • 48
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    Theoretical and applied genetics 77 (1989), S. 253-259 
    ISSN: 1432-2242
    Keywords: Heterosis ; Selection ; Drosophila ; Genotype x environment
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    Topics: Biology
    Notes: Summary Experiments were designed to examine whether heterosis would occur in crosses of Drosophila melanogaster populations adapted to 18 °C or 28 °C environments. Crosses were examined in parental environments, an intermediate environment (23 °C) and a mixed environment (alternating 18°/28°C). Parental populations did not show divergence for larval viability, cold shock or high temperature mortalities when tested in a common environment. However, the 28 °C population was less fecund than the 18 °C population, but had higher larval competitive ability and higher adult longevity. Heterosis for viability, cold shock mortality and high temperature mortality occurred in crosses between a population adapted to 18 °C and another adapted to 28 °C, but not in crosses between two populations adapted to the same temperature. The results suggest that, in the absence of drift, heterosis is expected in crosses between lines or populations with different histories of selection but not between lines with the same selection histories.
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  • 49
    ISSN: 1617-4623
    Keywords: Drosophila ; Vestigial ; Dihydrofolate reductase ; Aminopterin
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    Topics: Biology
    Notes: Summary Vestigial (vg) mutants of Drosophila melanogaster are characterized by atrophied wings. In this paper we show that: (1) aminopterin an inhibitor of dihydrofolate reductase (DHFR) and fluorodeoxyuridine (FUdR), an inhibitor of thymidylate synthetase induce nicks in the wings of wild-type flies and phenocopies of the vg mutant phenotype when vg/+ and vg B/+ flies are reared on these substances (vgB is a deficiency of the vg locus). Only thymidine and thymidylate can rescue the flies from the effect of aminopterin. We propose that the vg phenotype is due to a decrease in the dTMP pool in the wings. (2) Mutant vg strains yield more offspring on medium containing aminopterin than on normal medium. The resistance of vg larvae to the inhibitor seems specific to the gene. This is the first case of aminopterin resistance in living eucaryotes. In contrast sensitivity of the vg larvae to FUdR is observed. (3) An increase in the activity and amount of DHFR is observed in mutant strains as compared with the wild-type flies. Our data suggest that the vg + gene is a regulatory gene acting on the DHFR gene or a structural gene involved in the same metabolic pathway.
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  • 50
    ISSN: 1617-4623
    Keywords: Autoregulation ; LacZ fusion protein ; Northern hybridization ; Regulatory circuit ; Yeast
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    Topics: Biology
    Notes: Summary The mode of expression was investigated for two positive regulatory genes PHO2 and PHO4, whose products are indispensable for the transcriptional control of the structural genes of repressible acid phosphatase and the inorganic phosphate (Pi) transport system in Saccharomyces cerevisiae. Northern analysis of poly(A)+ RNA of the wild-type and the pho regulatory mutants with PHO4 DNA as hybridization probe and expressional analysis of a pho4′-'lacZ fused gene on a YEp plasmid revealed that PHO4 is expressed at a low level, constitutively, and independently of the PHO regulatory system and Pi in the medium. Similar analyses with PHO2 DNA indicated that PHO2 is expressed at an even lower level than PHO4, and is repressed by Pi and by the active PHO2 product, possibly at the translational level, while retaining a substantial level of basal activity.
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  • 51
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    Molecular genetics and genomics 216 (1989), S. 276-286 
    ISSN: 1617-4623
    Keywords: Methionine ; Initiator tRNA ; tRNA(met) ; Yeast ; Multigene family
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    Topics: Biology
    Notes: Summary Standard laboratory yeast strains have from four to five genes encoding the methionine initiator tRNA (IMT). Strain S288C has four IMT genes with identical coding sequences that are colinear with the RNA sequence of tRNA I Met . Each of the four IMT genes from strain S288C is located on a different chromosome. A fifth IMT gene with the same coding sequence is present in strain A364A but not in S288C. By making combinations of null alleles in strain S288C, we show that each of the four IMT genes is functional and that tRNA I Met is not limiting in yeast strains with three or more intact genes. Strains containing a single IMT2, 3 or 4 gene grow only after amplification of the remaining IMT gene. Strains with only the IMT1 gene intact are viable but grow extremely slowly; normal growth is restored by the addition of another IMT gene by transformation, providing a direct test for IMT function.
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  • 52
    ISSN: 1617-4623
    Keywords: Yeast ; Nuclear genes ; Mitochondrial translation ; Mitochondrial splicing ; Suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have cloned three distinct nuclear genes, NAM1, NAM7, and NAM8, which alleviate mitochondrial intron mutations of the cytochrome b and COXI (subunit I of cytochrome oxidase) genes when present on multicopy plasmids. These nuclear genes show no sequence homology to each other and are localized on different chromosomes: NAM1 on chromosome IV, NAM7 on chromosome XIII and NAM8 on chromosome VIII. Sequence analysis of the NAM1 gene shows that it encodes a protein of 440 amino acids with a typical presequence that would target the protein to the mitochondrial matrix. Inactivation of the NAM1 gene by gene transplacement leads to a dramatic reduction of the overall synthesis of mitochondrial protein, and a complete absence of the COXI protein which is the result of a specific block in COXI pre-mRNA splicing. The possible mechanisms by which the NAM1 gene product may function are discussed.
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  • 53
    ISSN: 1617-4623
    Keywords: Yeast ; Mitochondrial 15 S rRNA ; Ribosomal frameshifting ; Paromomycin resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The leaky expression of the yeast mitochondrial geneoxi1, containing a frameshift mutation (+1), is caused by natural frameshift suppression, as shown previously (Fox and Weiss-Brummer 1980). A drastic decrease in the natural level of frameshifting is found in the presence of thepar r-454 mutation, localized at the 3′ end of the 15 S rRNA gene. This mutation causes resistance to the antibiotic paronomycin in the yeast strains D273-10B and KL14-4A (Li et al. 1982; Tabak et al. 1982). The results of this study imply that in the yeast strain 777-3A this mutation alone is sufficient for restriction of the level of natural frameshifting but is insufficient to confer resistance to paromomycin. A second mutation, arising spontaneously with a frequency of 10−4 leads, in combination with thepar r-454 mutation, to full paromomycin resistance in strain 777-3A.
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  • 54
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    Molecular genetics and genomics 218 (1989), S. 118-126 
    ISSN: 1617-4623
    Keywords: Drosophila ; Regulation ; yellow gene ; Germline transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have assessed the DNA sequence requirements for the correct spatial pattern and phenotypic expression of y in the late embryo/larvae. The wild-type larval phenotype requires both the regions between-294 bp and-92 bp and a portion of the intron; the sequence element(s) located within the intron can act in a position independent manner to effect the wild-type larval phenotype. The larval expression pattern was examined by tissue experiments in situ and by staining germline transformants derived from various y/lacZ fusion constructs. The larval expression of y is restricted to the mouthparts, microsetae and anal plates. While the-495 bp to+194 bp region alone cannot effect a wild-type larval expression pattern, this region in conjunction with the intron appears to be sufficient to drive β-gal expression in an essentially wild-type pattern. Our data further suggest that the-294 bp to-92 bp region contains elements which specify the larval pattern and that the element(s) in the intron normally act to enhance the level of expression necessary for the wild-type larval phenotype. We also present a phenotypic analysis of the adult cuticle structures of germline transformants derived from a variety of deletion and rearrangement constructs of the y gene. This analysis has revealed several new features associated with the regulation of y expression.
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  • 55
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    Molecular genetics and genomics 215 (1989), S. 281-285 
    ISSN: 1617-4623
    Keywords: Drosophila ; achaete-scute complex ; myc ; Protein domains ; Genomic search
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several genes of the achaete-scute complex (ASC) of Drosophila melanogaster encode a 60 amino acids long conserved domain which shares a significant homology with a region of the vertebrate myc proteins. Based on these results, the existence of a family of Drosophila genes that would share both this conserved domain and the neurogenic function of the AS-C has been postulated. To test this proposal, we have searched a D. melanogaster genomic library with a probe that encodes the conserved domain. Only under very low stringency hybridization conditions, clones not belonging to the AS-C cross-hybridized with the probe. Those that gave the strongest signals were characterized. Sequencing of the cross-hybridizing regions showed that they had no significant homology with the conserved domain, the sequence similarity extending at the most for 37 nucleotides. Although our results do not conclusively disprove the existence of a family of AS-C-like genes, they indicate that the conservation of the domain would be lower than that found for shared motifs in other families of Drosophila developmental genes.
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  • 56
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    Molecular genetics and genomics 215 (1989), S. 425-430 
    ISSN: 1617-4623
    Keywords: Yeast ; DNA repair ; RAD18 ; Chromosomal deletions ; Mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The RAD18 gene of Saccharomyces cerevisiae is involved in mutagenic DNA repair. We describe its isolation from a yeast library introduced into the centromeric YCp50 vector, a low copy number plasmid. The insert was sublconed into YCp50 and into the multicopy YRp7 plasmid. RAD18 is not toxic when present in multiple copies but the UV survival response indicates an heterogeneity in the cell population, a fraction of it being more sensitive. A DNA segment, close to RAD18, is toxic on the multicopy plasmid and may correspond to the tRAN sup61 known to be tightly linked to RAD18. Chromosomal deletions of RAD18 were constructed. The gene is not essential and the deleted strains have the properties of single site mutants. Thus, RAD18 appears to be essentially involved in DNA repair metabolism.
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  • 57
    ISSN: 1573-8477
    Keywords: Genetic elements ; isozymes ; life span ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Analysis of electrophoretic loci shows that at least four differences exist in isozymes of long- and short-lived populations ofD. melanogaster, descended by selection from a common ancestral stock. Adults of longlived populations differ in gene dosage of phosphoglucomutase (PGM), NAD malate dehydrogenase (MHD), NADP malic enzyme (ME) and by additional mobility variants of glucose-6-phosphate dehydrogenase (G6PD). Larvae, however, differ only by variants of G6PD. The differences in these enzymes, considered together with the greater flight endurance that long-lived populations have shown elsewhere, suggest that increased glycogen synthesis plays a significant role in the improved life span of selected populations. Adaptation to selection for increased life span may, therefore, derive from an improved ability to use dietary sucrose in the media provided. The distribution of electrophoretic loci agrees with the results of a study indicating the position of genetic elements contributing to life span.
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    Evolutionary ecology 3 (1989), S. 189-201 
    ISSN: 1573-8477
    Keywords: Developmental homeostasis ; life history traits ; Drosophila ; breeding site variation ; cactus ; Sonoran desert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Variation in life histories among populations of cactophilicDrosophila mojavensis has been hypothesized to be a by-product of a shift to one of two alternate host plants. When cultured on the ancestral and a secondary host cactus, a Baja population expressed shorter development times and smaller thorax sizes than a mainland population, but viability did not differ. Comparisons with all reciprocal F1 and F2 crosses between populations revealed that genetic differences in development time and thorax size were largely additive. Homeostasis in these life history traits was population specific, except for viability. Homeostasis in development time was greater in the Baja population than in the other crosses, suggesting dominance for decreased homeostasis in the mainland population. Underdominance in viability homeostasis of the F1 hybrids suggested some incompatibility between populations. Homeostasis in thorax size was greater in females than in males and differed among parental populations. Maintenance of heritable differences and genetic variation for homeostasis in these traits suggested a role for cactus-specific differences in environmental uncertainty caused by variation in breeding site duration and abundance in nature.
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  • 59
    ISSN: 1617-4623
    Keywords: Chromosomal walking ; Cut locus ; Drosophila ; Unstable mutations
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    Notes: Abstract We have cloned from the Oregon R strain of Drosophila melanogaster a 240 kb segment of DNA that contains the cut (ct) locus, and characterized the region for the presence of repetitive elements. Within this region at least five copies of the suffix element were detected, as well as several putatively novel mobile elements. A number of mutations obtained from the unstable ct MR2 strain and its derivatives were mapped within the cut locus. Comparison between parental and daughter strains indicates that frequently two or more independent transposition events involving the cut locus occur simultaneously within a single germ cell, thus providing a molecular basis for the transposition explosion phenomenon.
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  • 60
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    Molecular genetics and genomics 219 (1989), S. 397-403 
    ISSN: 1617-4623
    Keywords: Drosophila ; Pyrimidine biosynthesis ; Dihydroorotate dehydrogenase ; Molecular mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The dhod locus encodes dihydroorotate dehydrogenase, the fourth enzymatic step of de novo pyrimidine biosynthesis. This locus was cloned previously by a chromosome walk in cytogenetic region 85A. The location of dhod within 85A DNA has been determined by mapping two rearrangement mutations to a small DNA region. A nearly full-length cDNA clone of the dhod transcript was isolated and partially sequenced, to confirm its identity. The cDNA clone was also used to map the transcribed DNA. A 1.5 kb dhod RNA is described which is most abundant in embryos and displays minor length heterogeneity in pupae and adults. The developmental expression of this transcript is discussed relative to the expression of dihydroorotate dehydrogenase activity and other genes of the pyrimidine biosynthetic pathway.
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  • 61
    ISSN: 1617-4623
    Keywords: Chromosome fragmentation ; Mapping ; PHO13 sequence ; Phosphatase ; Yeast
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    Notes: Summary The structural gene, PHO13, for the specific p-nitrophenyl phosphatase of Saccharomyces cerevisiae was cloned and its nucleotide sequence determined. The deduced PHO13 protein consists of 312 amino acids and its molecular weight is 34635. The disruption of the PHO13 gene produced no effect on cell growth, sporulation, or viability of ascospores. The PHO13 locus was mapped at 1.9 centimorgans from the HO locus on the left arm of chromosome IV. By chromosome fragmentation, the PHO13 locus was found to be located about 72 kb from the left-hand telomere of chromosome IV and distal to the HO locus.
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  • 62
    ISSN: 1617-4623
    Keywords: Centromere ; Chromatin ; Hypersensitive sites ; Yeast
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary Isolated nuclei of Saccharomyces cerevisiae were incubated with five restriction nucleases. Out of the twenty-one recognition sequences for these nucleases in the centromere region of chromosome XIV, only five are accessible to cleavage. These sites map 11 by and 74 by to the left and 27 bp, 41 by and 290 by to the right, respectively, of the boundaries of the 118 by functional CEN14 DNA sequence. The distance between the sites accessible to cleavage and closest to CEN14 is 156 bp, suggesting this is the maximal size of DNA protected in CEN14 chromatin. The DNA in CEN14 chromatin protected against cleavage with DNase I and micrococcal nuclease overlaps almost completely with this region. Hypersensitive regions flanking both sides are approximately 60 by long. Analyses of other S. cerevisiae centromeres with footprinting techniques in intact cells or nucleolytic cleavages in isolated nuclei are discussed in relation to our results. We conclude that structural data of chromatin obtained with restriction nucleases are reliable and that the structure of CEN14 chromatin is representative for S. cerevisiae centromeres.
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  • 63
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    Molecular genetics and genomics 215 (1989), S. 190-199 
    ISSN: 1617-4623
    Keywords: Mutagen sensitivity ; Recombination ; Gene structure ; Drosophila ; mei-41
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mutagen-sensitive mutant mus(1)104 D1 of Drosophila melanogaster maps to a position on the X chromosome very close to the meiotic mutant mei-41 D5 . Both mutants have been characterized as mutagen-sensitive and defective in post-replication repair. In the present report we show by complementation studies that mus(1)104 and mus(1)103 are allelic with mei-41. In addition, two reported alleles of mus(1)104 lie between the mei-41 alleles A10 and D5. The size of the mei-41 locus is estimated to be about 0.1 centimorgans (cM). Because several alleles of mei-41 have been shown to reduce recombination and increase meiotic chromosome loss and nondisjunction, mus(1)104 D1 females were examined for defects in meiosis. Although there was no evidence for reduced recombination on the second chromosome in homozygous mus(1)104 D1 females, heterozygous mus(1)104 D1 /mei-41 〉D5 and mus(1)104 D1 /deficiency females showed reduced levels of recombination. However, there was no evidence of an increase in nondijunction in these females.
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  • 64
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    Molecular genetics and genomics 215 (1989), S. 257-265 
    ISSN: 1617-4623
    Keywords: Drosophila ; Maternal effect ; Syngamy ; Embryonic development ; Molecular cloning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The maternal effect locus fs(1) Ya is required for the fusion of the apposed sperm and egg pronuclei (syngamy) following fertilization in Drosophila. It is tightly linked to another complementation group, fs(1) Yb, needed for both oogenesis and embryogenesis. We have isolated a set of overlapping cloned sequences in the 3B4-6 region of the X chromosome encompassing the fs(1) Ya-fs(1) Yb region. A single 2.4 kb maternal transcript is encoded with-in this region, and an 8.5 kb DNA fragment that contains this transcript complements both fs(1) Ya and fs(1) Yb mutations. Northern and in situ hybridization analyses show that the maternal transcript is only present in nurse cells and oocytes beginning in previtellogenic stages, and is evenly distributed in the cytoplasm of 0–2 h syncytial embryos. The transcript is not detected in later stages of embryonic development. This expression pattern correlates closely with the genetic and developmental characteristics expected of the fs(1) Ya gene product.
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  • 65
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    Molecular genetics and genomics 215 (1989), S. 469-477 
    ISSN: 1617-4623
    Keywords: Drosophila ; Y chromosome ; Repetitive DNA ; Testis RNA ; Transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A cDNA clone bank was constructed from testis poly(A)+ RNA of Drosophila hydei and screened for clones which hybridize to Y chromosomal DNA sequences. The insert of clone cDhT14 hybridizes to a family of repeated DNA sequences with members distributed within the Y chromosome and elsewhere in the genome. This type of sequence has earlier been described as the Y-associated class of DNA. Southern blot analysis of DNA from different wild-type strains of D. hydei suggests that members of the T14 family of repeated DNA sequences are parts of a family of transposable elements. The genomic localization of the T14 family of repeated DNA sequences was revealed by in situ hybridization to metaphase and polytene chromosomes, and to transcripts of Y chromosomal lampbrush loops. Approximately 10–15 members (20%–30%) of the T14 sequence family reside in 8.3 kb PstI restriction fragments. A genomic clone of one of these DNA fragments, DhT14-8.3, hybridizes to transcripts on the Y chromosomal lampbrush loop “cones”, and in conventional in situ hybridization experments to region 12D/13A of the X chromosome and to region 112 of chromosome 5. The cDNA clone cDhT14 represents a part of an abundant testis RNA species of 5.0 kb. This RNA is also present in ovaries and in 0–3 h, 3–6 h and 6–12 h embryos, but less abundantly than in testes. Both the Y chromosomal site of the 8.3 kb PstI fragments and sites elsewhere in the genome are actively transcribed. At least one of the latter genomic sites is transcribed into the 5.0 kb RNA species. This poly(A)+ RNA is present in the cytoplasm of primary spermatocytes as shown by transcript in situ hybridization. The potential function of transcripts from Y chromosomal lampbrush loops is discussed.
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    Molecular genetics and genomics 217 (1989), S. 40-46 
    ISSN: 1617-4623
    Keywords: Gene dosage ; Gene expression ; Regulatory circuit ; Signal transmission ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Expression of the repressible acid phosphatase (rAPase) gene, PHO5, of Saccharomyces cerevisiae is repressed by a certain level of inorganic phosphate (Pi) in the medium and is derepressed when the Pi concentration is lowered. The Pi signals are conveyed to PHO5 by a regulatory system consisting of proteins coded for by the PHO2, PHO4, PHO80 and PHO81 genes. We have found that the transcription of PHO81 is regulated by Pi through the PHO regulatory system. Increasing the dosage of PHO4 and PHO81 by ligating each gene to YEP13 gives rise to, respectively, considerable and weak synthesis of rAPase by cultivation of the transformants in high-Pi medium; but in low-Pi medium, increased dosage of PHO4 stimulates the rAPase synthesis significantly, whereas PHO81 has no effect. Increased dosage of PHO2 stimulates rAPase synthesis considerably in low-Pi but not in high-Pi. A coordinate increase of PHO80 cancels the dosage effect of PHO4, but not that of PHO81. Coordinate increases of PHO80 and PHO2 give rise to the same phenotype as an increased dosage of PHO80 alone. The level of the PHO4 protein was found to be the limiting factor of the rAPase synthesis and the copy number of the PHO5 gene not to be. These facts accord with the idea that the PHO80 protein transmits the Pi signals to the PHO5 gene via the PHO4 protein, whereas the PHO2 protein does not have a direct function in the signal transmission.
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  • 67
    ISSN: 1617-4623
    Keywords: Yeast ; MFα1 leader ; Gene fusion ; Secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The constuction of two fused genes is described. One involves the in-frame fusion of the yeast prepro-α-factor coding sequence, and the Escherichia coli lac Z gene. The second gene fusion utilizes a 103 bp yeast invertase NH2-terminal coding sequence at the fusion junction of the hybrid gene described above. The gene fusions, under the control of the α-factor promoter, expressed active β-galactosidase in α haploid yeast cells. The activity could be regulated in a temperature-sensitive sir3 mutant. The incorporation of the invertase coding sequence at the MFα1-lacZ fusion junction provided significantly higher levels of β-galactosidase activity. A substantial quantity of the hybrid proteins generated from the gene fusions was primarily localized in the intracellular membranes of yeast cells, while a processed form could be secreted into the periplasm.
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    Journal of bioenergetics and biomembranes 21 (1989), S. 439-450 
    ISSN: 1573-6881
    Keywords: Yeast ; yeast mutant ; mitochondrial porin ; mitochondrial outer membrane ; lipid bilayer ; ion-channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Reconstitution experiments were performed on lipid bilayer membranes in the presence of purified mitochondrial porin from yeast and of detergent-solubilized mitochondrial outer membranes of a porin-free yeast mutant. The addition of the porin resulted in a strong increase of the membrane conductance, which was caused by the formation of ion-permeable channels in the membranes. Yeast porin has a single-channel conductance of 4.2 nS in 1 M KCl. In the open state it behaves as a general diffusion pore with an effective diameter of 1.7 nm and possesses properties similar to other mitochondrial porins. Surprisingly, the membrane conductance also increased in the presence of detergent extracts of the mitochondrial outer membrane of the mutant. Single-channel recordings of lipid bilayer membranes in the presence of small concentration of the mutant membranes suggested that this membrane also contained a pore. The reconstituted pores had a single-channel conductance of 2.0 nS in 1 M KCl and the characteristics of general diffusion pores with an estimated effective diameter of 1.2 nm. This means that the pores present in the mitochondrial outer membranes of the yeast mutant have a much smaller effective diameter than “normal” mitochondrial porins. Zero-current membrane potential measurements suggested that the second mitochondrial porin is slightly cation-selective, while yeast porin is slightly anion-selective in the open state but highly cation-selective in the closed state. The possible role of these pores in the metabolism of mitochondria is discussed.
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    Journal of comparative physiology 159 (1989), S. 237-242 
    ISSN: 1432-136X
    Keywords: Amylase ; Mosquitofish ; Rat ; Drosophila ; Structure ; Function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Amylases from the mosquitofish (Gambusia affinis holbrooki, Pisces: Poeciliidae) and rat were purified and compared withDrosophila amylases in terms of structure and function. At the structural level, amino acid compositions of the three amylases were compared. At the functional level, amylase activities were compared on various substrates and in the presence of inhibitors. While the amylases from all three organisms had properties typical of alpha-amylases, both structural and functional differences were observed. Using resemblance coefficients of distance and similarity from numerical taxonomy, it was determined that the amylases from the rat andDrosophila were more similar to each other than either was to amylase from the mosquitofish, and that structural differences between the amylases did not reflect functional differences, i.e. there was no correlation between amylase structural and functional distances.
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    Journal of chemical ecology 15 (1989), S. 663-676 
    ISSN: 1573-1561
    Keywords: Drosophila ; Diptera ; Drosophilidae ; triterpene glycosides ; cactus ; fitness components ; host-plant relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effects of pentacyclic triterpene glycosides extracted from agria and organ pipe cacti on three fitness parameters of the cactophilic fruit fly,Drosophila mojavensis were tested. Triterpene glycosides from organ pipe increased development time and reduced larval viability while those from agria produced smaller adults (reduced fecundity). In addition, the microbial communities in the organ pipe saponin media were less dense than those in the media to which agria saponins had been added. The role of cactus triterpene glycosides in the ecology of thisDrosophila species is discussed.
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    Journal of industrial microbiology and biotechnology 3 (1988), S. 9-14 
    ISSN: 1476-5535
    Keywords: Single cell protein ; Sucrose ; Yeast ; Thermotolerance ; Fermentation ; Kluyveromyces marxianus var.marxianus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Amino acid analyses were undertaken on single cell protein (SCP) produced by thermotolerant strains ofKluyveromyces marxianus var.marxianus grown on sugar cane molasses at 40°C. The maximum conversion of available sugars to biomass at 45°C was only 10.8% (g dry wt.·g−1 total sugars). The amino acid composition of the SCP did not differ markedly from that reported for other yeast species.
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    Journal of insect behavior 1 (1988), S. 3-15 
    ISSN: 1572-8889
    Keywords: host preference ; habitat selection ; experience ; learning ; Drosophila ; host races ; population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A field experiment with Drosophila melanogasterrevealed that when flies encounter a particular food type soon after emergence, the probability of their subsequently being attracted to such a resource is increased. In this experiment, the length of time flies experienced their postemergence environments was under the control of the flies themselves. The experiment thus realistically mimicked one form of experiential effect that may be important in nature. A theoretical model is developed which shows that enhanced adult preferences for the types of resources fed on as larvae can substantially increase the degree of host-based genetic subdivision within a polyphagous population.
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    Entomologia experimentalis et applicata 47 (1988), S. 81-88 
    ISSN: 1570-7458
    Keywords: imaginal diapause ; male mating activity ; genetics ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les femelles de D. triauraria Bock & Wheeler (Dipt. Drosophilidae) sont connues pour présenter une diapause reproductrice aux photophases courtes. Les mâles eux aussi ont révélé une activité sexuelle réduite aux photophases courtes, c'est-à-dire qu'ils sont entrés comme les femelles en diapause reproductive. Les photophases critiques pour l'induction de la diapause des mâles et des femelles n'ont pas présenté de différences. Les diapause des mâles et des femelles s'achèvent même sous courtes photophases, mais la diapause mâle était quelque peu plus faible que la diapause femelle. La photophase critique et le taux de diapause ont varié en fonction de l'origine géographique dans l'espèce actuelle. Lors de croisements entre lignées diapausantes et non-diapausantes, la photophase critique et la durée de la diapause ont été héritées quantitativement. A partir de ces expériences et d'expériences précédentes de croisements (Kimura, 1983), quelques modèles de méchnisme d'induction de la diapause de cette espèce sont proposés.
    Notes: Abstract In Drosophila triauraria Bock & Wheeler (Diptera: Drosophilidae) of which females were known to enter reproductive diapause at short daylengths, males also showed reduced mating activity at short daylengths, i.e., males as well as females entered reproductive diapause. The critical daylength for diapause induction did not differ between females and males. Both male and female diapause ended even under short daylengths, but the male diapause was somewhat weaker than the female diapause. The critical daylength and the diapause rate varied geographically in this species. In the cross between diapausing and non-diapausing strains, the critical daylength and the diapause duration inherited in a quantitative manner. On the basis of the present and previous crossing experiments, some models are proposed on the mechanism of diapause induction of this species.
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  • 74
    ISSN: 1432-0983
    Keywords: Ribosomal protein ; Immunological homology ; Yeast ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Polyclonal antibodies raised against ribosomal protein (r-protein) L2 of Schizosaccharomyces pombe were used to check for cross-reaktions with total r-proteins of rat liver. Using this procedure, the rat liver r-proteins, L4 and L24, were identified as being immunologically related to yeast L2. In addtional, homologies between rat liver L4 and L24 were detected. The possible implications for the regulation of r-protein synthesis are discussed.
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    Current genetics 13 (1988), S. 291-297 
    ISSN: 1432-0983
    Keywords: Yeast ; Nuclear matrix ; Plasmid stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acentric yeast plasmids are mitotically unstable, apparently because they cannot freely diffuse after replicating and therefore are not included in the daughter nucleus. This behavior could result if plasmids remain attached to structural elements of the nucleus after replicating. Since DNA replication is believed to take place on the nuclear matrix, we tested whether there was a correlation between the mitotic stability of a given plasmid and the extent to which it was found associated with residual nuclear structures. Residual nuclei were prepared from yeast nuclei by extraction with either high salt, 2 M NaCl, or low salt, 10 mM lithium diiodosalicylate (LIS). Hybridization analysis was used to estimate the fraction of plasmid molecules remaining after nuclei were extracted. We examined the extent of matrix association of three ARSI plasmids, Trpl-RI circle (1.45 kb), YRp7 (5.7 kb) and pXBAT (45.1 kb) with mitotic loss rates ranging from 3–25%. In addition we examined the matrix binding of the endogenous 2 μm plasmid and the 2 μm-derived YEp 13 which is relatively stable in the presence of 2 μm and less stable in cir° strains. Among the ARS1 plasmids we observed a negative correlation between stability and matrix association, consistent with models in which binding to the nuclear matrix prevents passive segregation of ARS1 plasmid molecules. No such correlation was observed among the 2 μn plasmids. Among all plasmids examined there is a positive correlation between size and matrix association.
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  • 76
    ISSN: 1432-0983
    Keywords: Yeast ; Cloning ; ODC ; Complementation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A DNA fragment containing the gene encoding orotidine 5′-phosphate decarboxylase (ODC) from the yeast, Schwanniomyces occidentalis (formerly castellii) has been isolated from a genomic library constructed in the S. cerevisiae expression vector, pYcDE8. A recombinant plasmid, p2-lA, containing a 2.47 kb insert was shown to complement the ura3-52 mutation of several strains of S. cerevisiae. This DNA insert was shown to be from Schwanniomyces occidentalis by Southern hybridization analysis. A restriction enzyme cleavage map of the insert has been derived and the ODC gene localized to a 1.1 kb region by deletion analysis. In addition, we have demonstrated that expression of ODC is not dependent on the ADHI promoter carried on pYcDE8. This is the first report of the cloning of a gene from a member of the genus Schwanniomyces.
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  • 77
    ISSN: 1432-0983
    Keywords: Yeast ; Gene regulation ; Saccharomyces cerevisiae ; PDCI promoter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 870 by promoter fragment of the PDC1 gene that includes the carbon source dependent regulatory regions was investigated using 5′ and 3′ promoter deletions. The results indicate that glucose and ethanol regulation of PDC1 transcription are independently controlled by distinct cis-acting regions. The consensus sequence AAATCGATA may play a role in this regulation, while the sequence (ATCA)AACCT may be important in transcription initiation.
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    ISSN: 1432-0983
    Keywords: Gene regulation ; Cell cycle ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Expression of the thymidylate synthase gene (TMPI) of Saccharomyces cerevisiae increases during the late G1 phase of the cell cycle. Using a series of gene fusions, which have placed the Escherichia coli lacZ gene under transcriptional and translational control of different portions of the TMPI gene, we have demonstrated the existence of three different regions which are important for expression. One of these regions, which was localized to within 270 base pairs of the translation start codon, is involved in the periodic expression of TMPI transcript. A second region, the deletion of which resulted in reduced levels of TMPI expression, is at least partially encoded by DNA sequences between 270 and 377 base pairs upstream of the translation start codon. A third region, located within the N-terminal 112 codons of the TMPI gene, apparently encodes information involved in a post-translational control mechanism.
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  • 79
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    Current genetics 13 (1988), S. 455-460 
    ISSN: 1432-0983
    Keywords: Yeast ; Gene conversion and mutation ; CDC8 locus ; Cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The induction of mitotic recombination in theCDC8 locus was studied in a diploid strain heteroallelic forcdc8 mutations (cdc8-1/cdc8-3); mitotic reversion was studied in strainscdc8-1/cdc8-1 andcdc8-3/cdc8-3. Conversion and reversion did not occur in those cells blocked at the S stage of the cell cycle by exposure to a nonpermissive temperature. In stationary phase cells irradiated just prior to exposure to temperature stress, the induction of recombinants was rather low and the induction of revertants was minimal. Conversely, a significant induction ofcdc + occurred in logarithmic phase cells subjected to the same treatment. Irradiation of synchronously dividing cultures revealed that intragenic recombination occurs at all three stages of the cell cycle- G1, S and G2. It was also found that UV-induced gene reversion can occur during the S and G2 stages, but not during the G1 stage of the cell cycle.
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  • 80
    ISSN: 1432-0983
    Keywords: Mitotic recombination ; DNA repair ; Yeast ; RAD52
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The RAD52 gene is required for much of the recombination that occurs in Saccharomyces cerevisiae. One of the two commonly utilized mutant alleles, rad52-2, increases rather than reduces mitotic recombination, yet in other respects appears to be a typical rad52 mutant allele. This raises the question as to whether RAD52 is really necessary for mitotic recombination. Analysis of a deletion/insertion allele created in vitro indicates that the null mutant phenotype is indeed a deficiency in mitotic recombination, especially in gene conversion. The data also indicate that RAD52 is required for crossing-over between at least some chromosomes. Finally, examination of the behavior of a replicating plasmid in rad52-1 strains indicates that the frequency of plasmid integration is substantially reduced from that in wild type, a conclusion consistent with a role for RAD52 in reciprocal crossing-over. Analysis of recombinants arising in rad52-2 strains suggests that this allele may result in the increased activity of a RAD52-independent recombinational pathway.
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  • 81
    ISSN: 1432-0983
    Keywords: Informational suppressors ; Modifier ; Yeast ; tRNAs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mutants of Saccharomyces cerevisiae were selected that would interact with ochre (UAA) suppressors so as to allow ochre -suppressor dependant amber (UAG) suppression, but which do not exhibit opal (UGA) suppression. Strains mutant at four distinct loci were isolated, and two of these are recessive mutations while the other two behave as dominants or semidominants. MOS3 has some suppressor activity in the absence of a resident SUP4-o gene and shares other characteristics with previously described omnipotent suppressors. MOS4, mos1 and mos2, on the other hand, exhibit no suppressor activity in the absence of a resident SUP4-o gene but do exhibit suppression of UAG alleles when there is a resident SUP4-o gene. These latter modifier strains do not interact with a SUP4-o gene to suppress UGA alleles. By genetic and physiological criteria the MOS4, mosl, and most mutations appear to be different than previously described allosuppressors or modifiers of suppression.
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  • 82
    ISSN: 1432-0983
    Keywords: Yeast ; CDC8 gene ; DNA replication, recombination, mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The conditional cdc8 mutant is known to be defective, under restrictive conditions, in the elongation of DNA during synthesis. In yeast the CDC8 gene encodes thymidylate kinase. We show here that UV-induced gene conversion and gene mutation events require the participation of this CDC8 gene. Thus, the same thymidylate kinase is incolved both in DNA replication and in UV-induced gene conversion and gene mutation in yeast.
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  • 83
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    Journal of molecular evolution 28 (1988), S. 145-150 
    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase ; Drosophila ; Enzyme kinetics ; Product inhibition ; Microevolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Because natural populations ofDrosophila melanogaster are polymorphic for different allozymes of alcohol dehydrogenase (ADH) and becauseD. melanogaster is more tolerant to the toxic effects of ethanol than its sibling speciesD. simulans, information regarding the sensitivities of the different forms of ADH to the products of ethanol degradation are of ecological importance. ADH-F, ADH-S, ADH-71k ofD. melanogaster and the ADH ofD. simulans were inhibited by NADH, but the inhibition was relieved by NAD+. The order of sensitivity of NADH was ADH-F〈ADH-71k, ADH-S〈ADH-simulans with ADH-F being about four times less sensitive than theD. melanogaster enzymes and 12 times less sensitive than theD. simulans enzyme. Acetaldehyde inhibited the ethanolto-acetaldehyde activity of the ADHs, but at low acetaldehyde concentrations ethanol and NAD+ reduced the inhibition. ADH-71k and ADH-F were more subject to the inhibitory action of acetaldehyde than ADH-S and ADH-simulans, with ADH-71k being seven times more sensitive than ADH-S. The pattern of product inhibition of ADH-71k suggests a rapid equilibrium random mechanism for ethanol oxidation. Thus, although the ADH variants only differ by a few amino acids, these differences exert a far larger impact on their intrinsic properties than previously thought. How differences in product inhibition may be of significance in the evolution of the ADHs is discussed.
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  • 84
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    Mycopathologia 102 (1988), S. 3-8 
    ISSN: 1573-0832
    Keywords: Yeast ; carbon assimilation profiles ; liquid medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Liquid medium assays for yeasts carbon assimilation tests are the more precise but longer methods. For rapid and automated yeasts identification purposes we analysed the assimilation of 34 carbon compounds by 149 reference strains. Assays were carried in liquid shaken medium (Autobac∘ system) and readings were nephelemetric. Valuable results are obtained in 72 hours and their analysis allowed us to classify substrates for their ability to minimize the number of doubtful results.
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  • 85
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    Development genes and evolution 197 (1988), S. 19-26 
    ISSN: 1432-041X
    Keywords: Drosophila ; Morphogenesis ; Appendages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The phenotype of rotund (rn) null alleles is described, and compared to wild type. The mutants are expressed zygotically and cause position specific defects in certain imaginal discs (antenna, legs, wing, haltere and proboscis) and their corresponding adult derivatives. In the discs, specific folds are absent in rn mutants compared to wild type. Clonal analysis shows that the rn + gene is partially autonomous in its expression in cells destined to form certain distal parts of the adult appendages. The results are consistent with the idea that the rn + gene is required for normal morphogenesis of specific distal parts of the adult appendages.
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  • 86
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    Development genes and evolution 197 (1988), S. 40-48 
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeosis ; Tumorous-head ; Bithorax-complex mutant ; Morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transformations of tumorous-head Drosophila melanogaster were examined in order to investigate whether head structures were replaced by specific abdominal structures. Heads selected for the presence of genital structures were analyzed in detail. Female abnormalities included any combination of vaginal teeth, vulvar papillae, sensilla trichodea, abdominal tergites 6 (T6), 7 (T7), 8 (T8) and anal plate. Anal plate was observed in the prefrons and rostral membrane, while all other genital structures were intimately associated with modified shingle cuticle. Male abnormalities included transformation of antennal structures to penis, clasper teeth, lateral plate, anal plate and eye to T6. The distribution of each type of homeotic structure was confined to general regions of the eye-antenna, with no precise dividing lines between them. However, the spatial sequence of homeotic structures in the eye-antenna was generally the same as the sequence of the same structures in the posterior abdomen.
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  • 87
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    Development genes and evolution 197 (1988), S. 457-470 
    ISSN: 1432-041X
    Keywords: Neurogenesis ; Neurogenic genes ; Achaetescute complex ; Daughterless ; Genetic interactions ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Drosophila melanogaster the neuroblasts separate from epidermoblasts to give rise to the neural primordium. This process is under the control of several genes. The group of the so-called neurogenic genes is required for epidermal development; other genes, comprising those of the achaete-scute complex and daughterless, are required for neural development. We have studied the relationships between both groups of genes in two different ways. We have analyzed the phenotype of double-mutant embryos and our results show that the neural hyperplasia caused by neurogenic mutations can be partially prevented if a mutation in one of the other genes is present in the same genome. Only the neural cells that do not require the function of a particular gene of the achaete-scute complex in the wild-type seem to develop to a neural fate in the double mutant embryos. At least some of the genetic interactions affect the transcriptional level, as shown by in situ hybridization, since the territories of transcription of the achaetescute genes are expanded in neurogenic mutants. All cells of the neurogenic region of the double mutants apparently initiate neural development. However, during later development some of these cells switch their fate either to epidermogenesis or to cell death and this leads to the final phenotype of the double mutants. We discuss these results with respect to the events of early neurogenesis.
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  • 88
    ISSN: 1432-041X
    Keywords: Drosophila ; shibire ; Neuronal development ; Muscle ; Giant fiber pathway
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The temperature-sensitive mutation shibire (shi) in Drosophila melanogaster is thought to disrupt membrane recycling processes, including endocytotic vesicle pinch-off. This mutation can perturb the development of nerves and muscles of the adult escape response. After exposure to a heat pulse (6 h at 30° C) at 20 h of pupal development, adults have abnormal flight muscles. Wing depressor muscles (DLM) are reduced in number from the normal six to one or two fibers, and are composed of enlarged fibers that appear to represent fiber fusion; large spaces devoid of muscle fibers suggested fiber deletion. The normal five motor axons are present in the peripheral nerve PDMN near the ganglion. However, while some motor axons pass dorsally to the extant fibers, other motor axons lacking end targets pass into an abnormal posterior branch and terminate in a neuroma, i.e., a tangle of axons and glia without muscle target tissue. Hemisynapses are common in axons of the proximal PDMN and within the neuroma, but they are rarely seen in control (no heat pulse) shi or wild-type flies. All surviving muscle fibers are innervated; no muscle tissue exists without innervation. Fibrillar fine structure and neuromuscular synapses appear normal. Fused fibers have dual innervation, suggesting correct and specific matching of target tissue and motor axons. Motor axons lacking target fibers do not innervate erroneous targets but instead terminate in the neuroma. These results suggest developmental constraints and rules, which may contribute to the orderly, stereotyped development in the normal flight system. The nature of the anomalies inducible in the flight motor system in shi flies implies that membrane recycling events at about 20 h of pupal development are critical to the formation of the normal adult nerve-muscle pattern for DLM flight muscles.
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  • 89
    ISSN: 1432-041X
    Keywords: Cell interactions ; Cell commitment ; Neurogenesis ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell-cell interactions are involved in mediating developmental fate. An example is the decision of the neuroectodermal cells of Drosophila to develop as neural or epidermal progenitors, where cellular interactions participate in the process of acquisition of either cell fate. The results of heterochronic cell transplantations we describe here suggest that both neuroblasts and epidermoblasts are not irreversibly committed to a particular developmental fate. Rather, they retain the ability to interact with neighbouring cells and, under our experimental conditions, are capable of switching their fate during a relatively long period of time, i.e. until the end of embryonic stage 11.
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  • 90
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    Development genes and evolution 197 (1988), S. 435-440 
    ISSN: 1432-041X
    Keywords: Drosophila ; Homoeotic genes ; Segment differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Regulator of bithorax (Rg-bx)−, or trithorax (trx)− lethal larvae occasionally show a homoeotic transformation of the dorsal prothorax to mesothoracic structures. This transformation suggests a reduced activity of the Sex combs reduced (Scr) gene on the basis of gene dosage studies, as well as enhanced expression of the phenotypes of the weak Scr − alleles in Rg-bx − larvae. Morphological observations of adult flies doubly heterozygous for Rg-bx and Scr mutations also suggest the enhancement of an aspect of Scr adult phenotypes. I conclude that the Rg-bx + gene function is required for the optimal expression of the Scr gene in larval and imaginai cells.
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    Development genes and evolution 197 (1988), S. 507-512 
    ISSN: 1432-041X
    Keywords: Drosophila ; Reporter gene ; hairy ; Segmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Random insertions of a promotor fused to a reporter gene, such as Lac-Z, reveal regulatory sequences that confer temporal and spatial patterns of gene expression in eukaryotes. These patterns may reflect the activity of a neighbouring gene and thus lead to the isolation of new genes essential for normal development. Here, we demonstrate that this hypothesis is true for an insertion into the well characterized segmentation gene, hairy, in Drosophila. The insertion is homozygous lethal and fails to complement other hairy alleles, giving the phenotype described for hairy mutations. The insertion is located at 66D on the polytene chromosome map, is within 300–600 bp 5′ to the first hairy exon, and is orientated in the same sense (5′-3′) as the hairy transcription unit. Expression of β-galactosidase (β-gal), deriving from the insertion, follows closely the spatio-temporal patterns of expression of hairy gene product during embryogenesis. In addition, other sites of β-galactosidase expression are shown in the third larval instar stage and in the adult ovary. The results show that some insertions, giving restricted patterns of reporter gene expression, will reflect the temporo-spatial activity of a nearby gene.
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  • 92
    ISSN: 1432-041X
    Keywords: Drosophila ; Injection of embryo ; Daudi conditioned medium ; Rudimentary ovaries ; Mean number of ovarioles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Drosophila melanogaster embryos were injected before the blastoderm stage with conditioned media from several male Burkitt's lymphoma human cell lines and the Daudi cell line. Such injections do not have any effect on the male genital apparatus or on the female tract. The Daudi conditioned medium modifies the ovarian morphogenesis of the flies and the rudimentary ovaries obtained look like nymphal gonads. Moreover, they have a drastically reduced number of germ cells. The ovaries that looked functional contain numerous necrotic germ cells and the mean number of ovarioles per fly is significantly smaller than that of the controls. The abnormalities observed resemble the results of experimental and genetic lack of germ cells. They disappear at very high dilution (1×10−6).
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    Development genes and evolution 197 (1988), S. 231-238 
    ISSN: 1432-041X
    Keywords: Drosophila ; Electrical polarity ; Ovarian follicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Distribution of rhodamine-conjugated lysozyme injected into the sixteen-cell syncytium comprising the germ-line portion of theDrosophila follicle is shown to be affected by charge. Positive molecules are able to migrate through intercellular bridges from the oocyte to the nurse cells, but are unable to migrate detectably from nurse cells to the oocyte. Their negatively charged counterparts can move from the nurse cells to the oocyte, but are unable to traverse the intercellular bridges in the counter direction. This charge-dependent movement of molecules is accompanied by an electrical potential difference, focused across the nurse cell-oocyte bridges, which makes the nurse cells negatively charged to the oocyte. The addition of insect hemolymph to the physiological salt solution in which the experiments were performed resulted in only a small increase in the transmembrane resistance, but enhanced the potential difference between oocyte and nurse cells from 0.2±0.3 (SE) mV (nurse cells negative) to 2.3±0.45 (SE) mV (nurse cells negative).
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  • 94
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeosis ; Epidermal development ; Embryology ; Clonal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The complex genetic locuspolyhomeotic (ph) is a member of thePolycomb (Pc)-group of genes and as such is required for the normal expression of ANT-C and BX-C genes. It also has probably other functions since amorphicph alleles display a cell death phenotype in the ventral epidermis of 12-h-old embryos. Here it is shown that lethal alleles ofph (amorph and strong hypomorph) show transformation of most of their segments towards AB8. Theph + product is required autonomously in imaginal cells. The total lack ofph + function prevents viability of the cuticular derivatives of these cells.ph has a strong maternal effect on segmental identity and epidermal development that can not be rescued by one paternally supplied dose ofph + in the zygote. These phenotypes differ substantially from those of previously describedPc-group genes. AmongPc-group genes,ph seems to be the only one that is strongly required both maternally and zygotically for normal embryonic development.
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  • 95
    ISSN: 1432-041X
    Keywords: Drosophila ; Ultrabithorax ; Development ; Regulation ; Protein distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Most viable alleles of homeotic genes cause partial transformations within given lineages in a topographically specific fashion. We study this phenomenon as a way to understand the normal mechanisms involved in the spatial regulation of homeotic gene expression. To this end we have investigated the distribution of Ultrabithorax (Ubx) proteins in imaginai discs mutant for hypomorphic and neomorphic alleles of Ubx and alleles of trans-acting genes. We find that the morphological discontinuities observed in the adult transformations are caused by corresponding new patterns of the Ubx proteins in the imaginai anlagen. These novel patterns of Ubx proteins are understood as a consequence of a process of reinforcement-extinction of Ubx expression. The evidence suggesting that this process results from a positive feed-back loop and cell-cell interactions is discussed.
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  • 96
    ISSN: 1432-041X
    Keywords: Bithorax complex ; Drosophila ; Abdominal-B mutations ; Genetic mosaics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The phenotypic effects in imaginal hypodermal tissue of a number of Abdominal-B mutations of the bithorax complex are described. Evidence is given from complementation analysis that the phenotypic heterogeneity in both the spatial limits and the nature of the homeotic transformations produced is not an arbitrary classification of allelic differences that we find. We have used genetic mosaic analysis to support the interpretation that the Abdominal-B genetic unit can exist in a number of alternative functional states of expression during development and that individual Abdominal-B mutations may abolish some states whilst leaving others unaffected.
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  • 97
    ISSN: 1432-041X
    Keywords: Drosophila ; Segment polarity gene ; Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fused is a segmentation gene belonging to the segment-polarity class. Mutations at thefused locus are known to display pleiotropic effects, causing zygotically determined anomalies of ovaries and of some adult cuticular structures, and maternally determined embryonic segmentation defects. In order to determine the amorphic phenotype offused and to study the genetical basis of its pleiotropy, newfused alleles (18 viable and 11 lethal) were isolated. The phenotype of these mutants and of others already known are described, taking into account zygotic and maternal effects. The main results provided by this analysis are as follows. Firstly, allfused alleles show the whole complex fused phenotype, and a good correlation is observed between the strength of the wing and segmentation defects, suggesting that a single function is involved in both processes. Secondly, all embryonic and larval lethals carry deficiencies which allow us to localizefused between the 17C4 and 17D2 bands of the X-chromosome. Thirdly, the 24 viable and 2 pupal lethals examined behave as point mutants, as shown cytologically or by Southern blot analysis. However, only one of them, the pupal lethalfu mH63 was proven to carry a nullfused allele, since it displays in germ-line clones a strong maternal phenotype and a very low zygotic rescue, similar to those of the small deficiencyDf(1)fu z4. The phenotype of the amorphic mutant indicates that zygotic ezpression offused is required for normal metamorphosis, while maternal expression is necessary for a normal segmentation pattern, since a complete loss offused expression during oogenesis cannot be compensated zygotically.
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    Development genes and evolution 197 (1988), S. 75-91 
    ISSN: 1432-041X
    Keywords: Drosophila ; Maternal effect mutation ; Pattern formation ; Gastrulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The gastrulation defective (gd) locus is a maternally expressed gene in Drosophila required for normal differentiation of structures along the embryonic dorso-ventral axis. Cuticular defects of the offspring from females with different combinations of gd alleles comprised a phenotypic continuum. Complementation among several alleles produced normal offspring while progressively more severe mutations produced a graded loss of structures from ventral, and then lateral, blastoderm cells. The most severely affected embryos consisted entirely of structures derived from dorsal blastoderm cells. Histological examination of staged siblings from selected allelic combinations showed that internal tissues were similarly affected. The tissues observed in amorphic embryos support new, more dorsal, assignments of fate map positions for blastoderm precursors of the cephalopharyngeal apparatus, hindgut and ventral nerve cord. The loss of ventral and lateral structures did not occur through cell death and appeared to involve a change in blastoderm cell fate. A direct effect of the mutations on blastoderm cell determination, however, was insufficient to explain the development of the dorsalized embryos. Intermediate phenotypes suggested that cell interactions or movements associated with morphogenesis are required for the determination of some cell fates in the dorsoventral axis. Thus, the developmental fate of all blastoderm cells may not be fixed at the time of blastoderm formation.
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    Development genes and evolution 197 (1988), S. 115-123 
    ISSN: 1432-041X
    Keywords: X-Chromosome Loci ; Dominant maternal effect ; Segmentation genes ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A systematic search for X chromosome loci showing a dominant maternal interaction with the segmentation genes Krüppel, hunchback, knirps and hairy was performed using deficiencies spanning 65% of the X chromosome. No interaction with the knirps gene was observed, but five regions of the X chromosome showed a maternal dominant interaction with the Krüppel gene. Two of these regions also show a maternal dominant interaction with either hunchback (region 10A7–10A8) or hairy (region 10E1–10F3). In all of these interactions dead embryos were observed which showed the same defects as embryos homozygous for the segmentation gene tested. These results suggest that a complex repartition of maternal products necessary for subsequent segmentation may occur in the Drosophila egg.
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    Oecologia 75 (1988), S. 400-404 
    ISSN: 1432-1939
    Keywords: Vectoring ; Drosophila ; Cactophilic yeasts ; Dispersal ; Community structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At two locations in the Sonoran Desert, yeasts were sampled from species of Drosophila, the flies' cactus hosts, and other neighboring sources of cactophilic yeasts to determine the relation between the yeasts vectored by the fly and the yeasts found in their breeding sites. D. mojavensis, D. nigrospiracula, and D. mettleri vectored yeast assemblages significantly more similar to the yeast species found on the rot from which the flies were collected than to the yeasts found on other rots from the flies host cactus or other rotting cactus at the same site. Rots with Drosophila had fewer yeast species than those without flies, suggesting that flies were associated with younger rots. Rots with flies and the Drosophila also had more yeast species with the capability to produce ethyl acetate than rots without flies. The results support the contention that cactophilic Drosophila feed on a subset of the yeasts available in an area, and may act to maintain differences among the yeast communities found on different species of cactus.
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