bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of ecd1 mutation on the expression of genes mapped at the Drosophila melanogaster 3C11-12 intermoult puff
Authors: Furia Maria , D'avino Pier Paolo , Digilio Filomena A. , Crispi Stefania , Giordano Ennio , Polito Lino C. 
Published: September 2009

SummaryThe Drosophila melanogasterecd1 mutation causes a severe temperature-sensitive deficiency in the titre of the steroid hormone eedysone. This mutation was used to investigate the role of eedysone in both the transcription of the genes mapped at the 3C11–12 intermoult puff region and the puff formation. Thoroughly synchronized ecd1 larvae were shifted to the non-permissive temperature at various times of the development; after 24 or 48 h, the levels of the transcripts derived from Sgs-4, Pig-1 and ng-1, the three genes located at the 3C11–12 polytene bands, were determined. The results showed that the levels of the transcripts encoded by Pig-1 and ng-1 are unaffected by the drop in the ecdysone titre occurring in non-permissive conditions whereas the amount of Sgs-4 mRNA is greatly reduced. These data clearly indicate that transcription of the three genes mapped within the puff region is affected differently by the hormone. Furthermore, ecd1 larvae cultured at the non-permissive temperature show a prominent puff at the 3C11–12 polytene bands, indicating that eedysone is not essential for puff induction and that puff size is not simply correlated with high-level Sgs-4 transcription.
The effect of linkage and population size on inbreeding depression due to mutational load
Authors: Charlesworth D. , Morgan M. T. , Charlesworth B. 
Published: September 2009

SummaryUsing a stochastic model of a finite population in which there is mutation to partially recessive detrimental alleles at many loci, we study the effects of population size and linkage between the loci on the population mean fitness and inbreeding depression values. Although linkage between the selected loci decreases the amount of inbreeding depression, neither population size nor recombination rate have strong effects on these quantities, unless extremely small values are assumed. We also investigate how partial linkage between the loci that determine fitness affects the invasion of populations by alleles at a modifier locus that controls the selfing rate. In most of the cases studied, the direction of selection on modifiers was consistent with that found in our previous deterministic calculations. However, there was some evidence that linkage between the modifier locus and the selected loci makes outcrossing less likely to evolve; more losses of alleles promoting outcrossing occurred in runs with linkage than in runs with free recombination. We also studied the fate of neutral alleles introduced into populations carrying detrimental mutations. The times to loss of neutral alleles introduced at low frequency were shorter than those predicted for alleles in the absence of selected loci, taking into account the reduction of the effective population size due to inbreeding. Previous studies have been confined to outbreeding populations, and to alleles at frequencies close to one-half, and have found an effect in the opposite direction. It therefore appears that associations between neutral and selected loci may produce effects that differ according to the initial frequencies of the neutral alleles.
Mapping and characterization of a ‘speciation gene’ inDrosophila
Authors: Orr H. Allen 
Published: September 2009

SummaryAlmost nothing is known about the identity of the genes causing reproductive isolation between species. As a first step towards molecular isolation of a ‘speciation gene’, I mapped and partly characterized a gene causing hybrid male sterility inDrosophila. This analysis shows that sterility ofD. melanogastermales who carry the ‘dot’ fourth chromosome fromD. simulansis due entirely to a very small region of theD. simulanschromosome (including only about 5 salivary gland bands or approximately 250 kb of DNA). Thus the hybrid sterility effect of theD. simulansfourth chromosome is almost surely due to a single gene of very large effect (here namedhms, hybrid male sterile).Hmsis zygotically acting, and theD. simulansallele ofhmsis completely recessive. Furthermore, complementation tests suggest thathmsis not an allele of any known locus inD. melanogaster.
Further observation of paternal transmission ofDrosophilamitochondrial DNA by PCR selective amplification method
Authors: Kondo Rumi , Matsuura Etsuko T. , Chigusa Sadao I. 
Published: September 2009

SummaryBy designing 3′ ends of primers in PCR (polymerase chain reaction), a specific DNA fragment was selectively amplified in the presence of a 103-fold excess of highly homologous (sequence differenceca.2 %) opponent DNA. This technique was applied in detecting paternal leakage of mitochondrial DNA (mtDNA) in intraspecific crosses ofDrosophila simulansand interspecific crosses ofDrosophila simulansandDrosophila mauritiana. The mtDNA types of their progeny were analysed by selective amplification of the paternal mtDNA fragment possessing a polymorphic restriction site and detecting its cleaved fragments. Paternal mtDNA was detected in the progeny of 14 out of 16 crosses. The present result indicates small but frequent inheritance of sperm mtDNA inDrosophila, which is supportive to our previous finding.
Regulation of fitness in yeast overexpressing glycolytic enzymes: responses to heat shock and nitrogen starvation
Authors: Rosenzweig R. F. 
Published: September 2009

SummaryCurrent models based on the analysis of linear metabolic pathways at steady-state predict that large increases over wild type in the activity of one enzyme will not alter an organism's fitness. This prediction is tested at steps in a highly branched pathway under two conditions known to alter steady-state: heat shock and nitrogen starvation.Saccharomyces cerevisiaetransformants overproducing 1 of 4 enzymes in glycolysis (hexokinase B, phosphoglucose isomerase, phosphofructokinase, or pyruvate kinase) were subjected to heat shock in both exponential and stationary phases of growth. In neither phase does enzyme overexpression alter heat shock sensitivity. When starved for nitrogen in acetate medium, transformants overproducing hexokinase, phosphoglucose isomerase, and phosphofructokinase sporulate at the same rate and with the same frequency as cells harbouring only the plasmid vector. Current models therefore correctly predict the relationship between activity and components of fitness for 3 of 4 enzymes. By contrast, cells overexpressing pyruvate kinase sporulate poorly. This defect is not observed among cells transformed with a plasmid containing a Tn5 disrupted copy of thePYKgene. These findings are consistent with reports that implicate thePYKlocus in yeast cell cycle control and suggest that it may be challenging to model relations between fitness and activity for multifunctional proteins.
A particular P-element insertion is correlated to the P-induced hybrid dysgenesis repression inDrosophila melanogaster
Authors: Higuet Dominique , Anxolabéhére Dominique , Nouaud Danielle 
Published: September 2009

SummaryTransposable P elements inDrosophila melanogastercause hybrid dysgenesis if their mobility is not repressed. The ability to regulate the dysgenic activity of the P elements depends on several mechanisms, one of which hypothesized that a particular deleted P element (the KP element) results in a non-susceptibility which is biparentally transmitted. In this study totally nonsusceptible lines, and susceptible lines containing exclusively KP elements (IINS2 line and IIS2 line) were isolated from a M' strain. We show that non-susceptibility is correlated with a particular insertion of one KP element located at the cytological site 47D1. The repression ability of the GD sterility is determined by a recessive chromosomal factor, and cannot be due to the KP-element number. Here the repression of the P mobility is associated with reduction of the P transcripts and the inhibition of P promoter activity.
Comparative evolution of P–M system and infection by the sigma virus in French and Spanish populations ofDrosophila melanogaster
Authors: Fleuriet Annie , Kalmes Robert , Pascual Luis , Periquet Georges 
Published: September 2009

SummaryIn 1983, an extensive survey of populations ofD. melanogasterwas started in a southern French region (Languedoc) in two non-Mendelian systems: the P–M system of transposable elements and the hereditary Rhabdovirus sigma. Unexpectedly fast-evolving phenomena were observed and interesting correlations were noted, giving similar geographical pattern to the region in both systems. For these reasons, the analysis was continued and extended towards the north (Rhône Valley) and the south (Spain). In the P–M system, all the Languedoc populations evolved from 1983 to 1991 towards the Q type which is characteristic of the Rhône Valley populations. In contrast, M′ strains are currently observed in the southernmost French populations and in all Spanish ones, so that there is a clear pattern in their geographical distribution.The frequency of flies infected by the sigma virus dramatically increased from 1983 to 1988 in Languedoc; this increase was clearly correlated with some viral characteristics. But, in northern France, similar characteristics did not trigger any increase in the frequency of infected flies. The data presented here show that the distinctive features of Languedoc extend northwards through the Rhone Valley up to Lyon and disappears southwards before the Spanish border.
Chromosome interactions in P-M dysgenic male recombination ofDrosophila melanogaster
Authors: Eggleston P. , Exley K. A. 
Published: September 2009

SummaryThe frequency, distribution and structure of P elements on the second and third chromosomes of Texas 1, a wild-type inbred strain ofDrosophila melanogaster, were investigated byin situhybridization. These autosomes were isolated individually and used as P-element donors to study the frequency and distribution of male recombination events generated on recipient chromosomes which were originally devoid of P sequences. The P-element array of chromosome 2 was shown to generate higher male recombination frequencies on chromosome 3 than vice versa, despite having fewer P factors and fewer P elements in general. This is likely to be due to the presence and distribution of specific P-deletion derivatives, which vary in their ability to repress P mobility. The male recombination generated on recipient chromosomes is associated with the insertion of donated P sequences, but only in a small minority of cases could a novel P-element site be detected at, or near, the recombination breakpoint. The majority of such breakpoints appear to be associated either with unsuccessful P insertion, or with the action of P transposase attracted by P elements newly inserted elsewhere on the recipient chromosome. Recent evidence also suggests that a small proportion of the breakpoints may be associated with the action of P transposase alone. Male recombination breakpoints appear to be distributed effectively at random along the recipient autosomes, and their frequency of occurrence was shown to correlate with the physical length of DNA available between markers, as revealed by the polytene map distance.
The time of detection of recessive visible genes with non-random mating
Authors: Caballero Armando , Etheridge Alison M. , Hill William G. 
Published: September 2009

SummaryExpressions for the probability and average time of detection of a recessive visible gene in populations where there is partial selfing or partial full-sib mating are presented. A small increase in the proportion of inbred matings greatly reduces the average time until detection and increases the proportion detected. Unless the proportion of inbred matings or the population size is very small, the time and proportion detected are approximately independent of the population size.
A deleted hobo element is involved in the unstable thermosensitive vgal mutation at the vestigial locus in Drosophila melanogaster
Authors: Bazin C. , Williams J. , Bell J. , Silber J. 
Published: September 2009

SummaryWe have described a new unstable mutant of the vestigial locus isolated from a natural population. From this mutant, vestigialalmost (vgal), wild-type (vgal+), and extreme (vgext), alleles arose spontaneously. The molecular analysis of vgal shows that the mutation is due to a 1874 bp hobo element inserted in a vestigial intron. Two distinct kinds of events lead a wild-type phenotype. Three independent vgal+ alleles result from an excision of the hobo element and two other vgal+ alleles have further deletions of hobo sequence. The sequence of one of them shows a 1516 bp hobo insertion at the same place and in the same orientation as the 1874 bp insertion. In the vgext alleles, we found a 5′ or 3′ variably sized deletion of vg sequences. One of them, which has been cloned and sequenced, has a deletion finishing exactly at the left terminal repeat′ hobo element. The genetic implications of these different genetic structures are discussed.
Identification of ornithine decarboxylase as a trait gene for growth in replicated mouse lines divergently selected for lean body mass
Authors: Gray A. , Tait A. 
Published: September 2009

SummaryStudies of lines of mice selected for body mass have shown that there is a significant genetic component affecting this trait although the nature of the genes involved remains to be elucidated. Using replicate lines of mice, our studies have shown that two different variants of the mouse ornithine decarboxylase (ODCase) gene have been selected in replicate lines of mice selected for high and low lean body mass respectively. One variant is associated with an increased peak of ODCase activity in embryos (10–13 days of gestation) in all high mass lines and with a restriction fragment length polymorphism of the expressed gene. The increased ODCase activity coincides with increased ODCase mRNA levels in the high mass selected lines. These results provide evidence implicating ornithine decarboxylase as a major factor in cell growth, and as a candidate ‘trait gene’.
Linkage disequilibrium in thewhitelocus region ofDrosophila melanogaster
Authors: Miyashita Naohiko T. , Aguadé Montserrat , Langley Charles H. 
Published: September 2009

SummaryLinkage disequilibrium between molecular polymorphisms in a 10 kb region in thewhitelocus ofDrosophila melanogaster, revealed with a battery of four-cutter restriction enzymes, was investigated in 266 lines sampled from seven natural populations around the world. A total of 73 (35 restriction site, 37 insertion/deletion and 1 inversion) polymorphisms were detected, of which 55 non-unique polymorphisms were analysed for linkage disequilibrium. Clustering of significant linkage disequilibrium was observed in the transcriptional unit of thewhitelocus as in Miyashita & Langley (1988). It was shown that about two thirds of the 2-locus combinations showing significant linkage disequilibrium have similar degree and direction of association over different populations. Despite lower divergence in allelic frequencies of molecular polymorphisms among populations, an increase in the proportion of 2-locus pairs showing significant linkage disequilibrium is observed in the transcriptional unit. Large values of Ohta'sDmeasure ratio (1982a, b) cluster in the transcriptional unit, and correspond to significant linkage disequilibria. Although the exact molecular mechanism is not clear, these results suggest that epistatic selection is responsible for significant linkage disequilibrium in the transcriptional unit of this locus
The genetic basis of response in mouse lines divergently selected for body weight or fat content. I. The relative contributions of autosomal and sex-linked genes
Authors: Hastings Ian M. , Veerkamp Roel F. 
Published: September 2009

SummaryLines of mice have been divergently selected for over forty generations on either body weight or fat content. Reciprocal crosses were made between the divergent lines and the offspring backcrossed to the parental lines. The resulting data allowed us to investigate the genetic basis of response, including two features of particular interest: (i) the relative contribution of autosomal and sex-linked genes and whether any significant Y chromosome or cytoplasmic effects were present (ii) the mechanism of gene action, whether predominantly additive or whether significant dominance effects were present. A large additive sex-linked effect was observed in lines selected on body weight which accounted for approximately 25% of the divergence. The remaining 75% of the divergence appeared to be autosomal. There was no apparent sex-linked effect in lines selected on fat content and the response appeared to be entirely autosomal and additive.
Genotypically unbalanced diploid ↔ diploid foetal mouse chimaeras: possible relevance to human confined mosaicism
Authors: West John D. , Flockhart Jean H. 
Published: September 2009

SummaryTwo series of mouse chimaeras were produced by aggregating pairs of eight-cell embryos that differed at theGpi-1slocus, encoding glucose phosphate isomerase (GPI-1); the paired embryos were respectively homozygousGpi-1sa/Gpi-1saandGpi-1sb/Gpi-1sb. Chimaeric blastocysts were transferred to pseudopregnant females, that were homozygousGpi-1se/Gpi-1seand produced only GPI-1 C enzyme. Quantitative electrophoresis of GPI-1 was used to estimate the contribution of each embryo (GPI-1 A and GPI-1B enzyme activity) to the foetus, placenta and other extraembryonic tissues of 12½ day chimaericconceptuses. For both series of chimaeras, the distributions of %GPI-1A in different tissues were classified as (1) balanced and typical, (2) balanced but atypical or (3) unbalanced. One series of chimaeras was clearly unbalanced, so that the cells derived from the (C57BL × CBA/Ca)F2embryo (Gpi-1sb/Gpi-1sb) predominated over those derived from the BALB/c inbred strain (Gpi-1sa/Gpi-1sa) in most foetuses. Two significant observations were made concerning this unbalanced series. Firstly, the mean composition of the placenta and other extraembryonic tissues was similar to that in the foetus i.e. also unbalanced with (C57BL × CBA/Ca)F2(abbreviated to BF2) cells predominating. Secondly, despite this generalizeddeficiency of BALB/c cells, there were differences in the frequency of non-chimaeric tissues between different developmental lineages. In 20/34 chimaeric conceptuses in the unbalanced series only BF2cells were detected in the foetus, whereas both BF2and BALB/c cells were present in at least one of the extraembryonic tissues. This group of chimaeras, therefore, shows some similarities to human confined mosaicism. Although chimaerism occurred more often in the primitive endoderm (hypoblast) lineage (yolk sac endoderm and parietal endoderm) than in the placenta, this may also be the case in human mosaics. The mosaic status of the human yolk sac endoderm is usually unknown so it is possible that mosaicism often occurs in the yolk sac endoderm as well as the trophectoderm in human ‘confined placental mosaicism’. The uniformly unbalanced phenotype seen in the mouse chimaeras may be a result of generalized cell selection against BALB/c cells in all tissues. As an alternative explanation, we propose that most of the BALB/c cells in the blastocyst are allocated to the mural trophectoderm, which has a limited mitotic potential and so contributes little to the mid-gestation conceptus. Further work is required to test these possibilities.
Polymorphism and linkage analysis of the prothoracicotropic hormone gene in the silkmoth,Bombyx mori
Authors: Shimada Toru , Hasegawa Tsuyoshi , Matsumoto Kayoko , Agui Noriaki , Kobayashi Masahiko 
Published: September 2009

SummaryWe looked for polymorphism of the prothoracicotropic hormone gene locus (Ptth) among inbred strains of the silkmoth,Bombyx mori, by invitroDNA amplification (polymerase chain reaction), and found three alleles,PtthA,PtthBandPtthC. ThePtthAallele contained a third intron consisting of 680 bp and a fourth intron of 350 bp.PtthBcontained the same size third intron but a longer fourth intron of 490 bp, while Ptthc had a longer third intron of 1080 bp and a shorter fourth intron of 350 bp. In 29 strains which we examined, 9 strains hadPtthA, 8 strains hadPtthB, and 2 strains had Ptthc. The other 10 strains had heterogeneous genotypes with the same 3 alleles.
IR hybrid dysgenesis increases the frequency of recombination inDrosophila melanogaster
Authors: Chaboissier Marie-Christine , Lemeunier Françoise , Bucheton Alain 
Published: September 2009

SummaryThe I factor is a LINE-like transposable element responsible for the I-R system of hybrid dysgenesis inDrosophila melanogaster. Inducer strains of this species contain several I factors whereas reactive strains do not. I factors are stable in inducer strains, but transpose at high frequency in the germ-line of females, known as SF females, produced by crossing reactive females and inducer males. Various abnormalities occur in SF females, most of which result from this high rate of transposition. We report here that recombination is increased in the germ-line of these females. This is a new characteristic of the I-R system of hybrid dysgenesis that might also be associated with transposition of the I factor.
Recent evolution of mousethaplotypes at polymorphic microsatellites associated with thetcomplex responder (Tcr) locus
Authors: Ardlie Kristin G. , Silver Lee M. 
Published: September 2009

SummaryMicrosatellites closely associated with each member of theTcp1Ogene family were amplified simultaneously fromthaplotype and wild-type forms of mouse chromosome 17, by PCR. Thetcomplex responder (Tcr) locus, which plays a central role in transmission ratio distortion, maps within theTcp10cluster on thethaplotype. Thus the amplified set of microsatellite loci (referred to collectively asTcp10ms) provides a direct marker for this central component of the meiotic drive system associated with all naturally occurringthaplotypes. A uniqueTcp10mspattern of microsatellite alleles was obtained for a number of independent, laboratory-maintained complete and partialthaplotypes. Independenttchromosomes found in wild mice from US populations also had unique patterns, even when they were classified within the same lethal complementation group. Wild and laboratory chromosomes in thetw5group showed similarly-sized but non-identical Tcp10ms patterns, suggesting they share a recent common ancestor. These chromosomes are likely to have derived from an ancestral chromosome within the founding population of North American house mice. The Tcp10ms pattern was also shown to be useful in field studies for distinguishing among independentthaplotypes, when more than one is present within a single population.