bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mating competition in artificial populations ofDrosophila melanogasterpolymorphic forebony: II. A test for minority male mating advantage
Authors: Søndergaard Leif 
Published: September 2009

SummaryMating competition experiments withD. melanogasterwere performed in light and darkness under conditions mimicking those under which artificial populations show a stable polymorphism for theebonygene (e). In both light and darkness a minority male mating advantage was found fore/ + males in competition with wild-type males, but in light only when ebony was in the majority. Homozygous wild-type males showed minority advantage only in light and ebony males only in darkness.
Heritable variation and heterozygosity under a balance between mutations and stabilizing selection
Authors: Slatkin Montgomery 
Published: September 2009

SummaryA model of the balance between mutations and stabilizing selection affecting a quantitative character is developed and analysed. This model is essentially a discretized version of the continuum-of-alleles models analysed previously by Kimura, Lande, Turelli and others, and is formally similar to the stepwise mutation models used to interpret electrophoretic data. The complete model cannot be solved even for a haploid species, but there are useful approximations for most parameter values of interest. The ‘house-of-cards’ approximation can be used when selection is strong relative to mutation, and a normal approximation can be used when selection is relatively weak. For intermediate levels of selection a new ‘five-allele’ approximation provides accurate results over a wide range of parameter values. The house-of-cards and five-allele approximations applied to recessive alleles in a diploid population show that, for a given mutation rate, a somewhat larger genetic variance is maintained at equilibrium than in a comparable model of additive alleles. Under directional selection, the increase in genetic variance is largest for alleles of large effect and is much smaller for alleles of intermediate or small effect. At an equilibrium under stabilizing selection, homozygotes would tend to have a higher average fitness than heterozygotes when each mutation has a relatively large effect (the house-of-cards approximation), with the reverse if each mutation has a small effect (the normal approximation).
Correlation of compound autosome segregation and sex-chromosome disjunction in femaleLucilia cuprina(Wied.) (Diptera: Calliphoridae)
Authors: Foster G. G. , Maddern R. H. 
Published: September 2009

SummaryInLucilia cuprina(Wiedemann) females, non-segregation of compound fifth-chromosomes is correlated with non-disjunction of theXchromosomes. Approximately two-thirds of eggs which inherit both maternal compound elements are nullo-X, suggesting that meiotic pairing betweenXchromosomes and compound autosomes has occurred. There was no evidence for pairing of the compounds and theXorYchromosome in males. A limited amount of data suggests that high non-segregation frequencies may occur in the offspring of putativeX/X/XandX/Ofemales. These results suggest the existence of non-homologous (distributive) pairing inL. cuprinafemales.
Autosomal assignment of OTC in marsupials and monotremes: implications for the evolution of sex chromosomes
Authors: Sinclair Andrew H. , Wrigley Jacyln M. , Graves Jennifer A. Marshall 
Published: September 2009

SummaryThe OTC gene coding for ornithine transcarbamylase is sex linked and subject toXinactivation in humans and mice. We have used a rat cDNA probe to localize OTC byin situhybridization in marsupials and monotremes. The gene maps to an autosomal site in two distantly related marsupial species and in one monotreme (the platypus); the first demonstration that a geneX-linked in one mammalian species may be autosomal in another. Since the conservation of the mammalianXis thought to be a consequence of its isolation by the inactivation mechanism, we propose that an autosomal or pseudoautosomal segment containing OTC has been recruited into the inactivated region of theXrather recently in eutherian evolution while it remained autosomal, or was translocated to an autosome, in metatherian and prototherian mammals.
An allele at the triose phosphate isomerase,Tpi-1locus on chromosome 6 recovered from feral mice
Authors: Bulfield Grahame , Ball Simon T. , Peters Josephine 
Published: September 2009

SummaryAn animal with low erythrocyte triose phosphate isomerase (TPI) activity was found amongst mice trapped on a farm in Leicestershire. The low TPI activity was caused by the segregation of a single co-dominant gene which also affected theKmfor glyceraldehyde-3-phosphate and heat stability of the enzyme. We designate the geneTpi-1, the structural locus for TPI, with theaallele in the common inbred strains and theballele derived from the wild-caught mouse.Tpi-1was known to be on chromosome 6 by somatic cell techniques and, as shown in a preliminary report (Peters & Bulfield, 1984), we have confirmed and extended this finding using three chromosome-6 marker genes giving the order:Sig-28-Lc-11-Miwh-16-Tpi-1.
Estimating the recombination parameter of a finite population model without selection
Authors: Hudson Richard R. 
Published: September 2009

SummaryAn estimator is proposed for the parameter C = 4Nc. where N is the population size andcis the recombination rate. The estimator is appropriate for use with sequence or restriction site data from random samples from within populations. Properties of the estimator are investigated for an infinite-sites neutral model using Monte Carlo simulations. The median and mode of the distribution of the estimator are close to the true value for all parameter values examined, but large data sets are required to obtain reliable estimates.
The murine cataractogenic mutation, Cat Fraser, segregates independently of the gamma crystallin genes
Authors: Rupert Jim L. , Kuliszewki Maciek , Tsui Lap-Chee , Breitman Martin L. , Gold Reynold J. M. 
Published: September 2009

SummaryThe murine mutation, Cat Fraser (CatFr), causes dominantly inherited ocular cataracts. Lenses of adult mice bearing this mutation contain reduced amounts of all seven γ-crystallin proteins and their corresponding transcripts. Levels of other lens proteins and transcripts appear normal and no extra-ocular effects of the mutation have been observed. The selective effect of this mutation on the γ-crystallins is consistent with the possibility that the site at which it occurs is involved in the coordinated regulation of the family of genes which encodes them. We have shown that several restriction fragment length polymorphisms in the γ-crystallin genes segregate independently of the CatFr mutation. Therefore, despite its selective effect on the expression of the γ-crystallin genes, the mutation is not linked to them. This observation rules out the possibility that the mutation is in a cis-acting regulatory site.
Three ENU-induced alleles of the murine quaking locus are recessive embryonic lethal mutations
Authors: Justice Monica J. , Bode Vernon C. 
Published: September 2009

SummaryThe quaking (qk) locus on mouse chromosome 17 has been defined by a single viable quaking allele. Three new alleles of quaking were selected after ENU mutagenesis by their failure to complement the quaking phenotype. Theqkk2allele was induced on wild-type chromatin and theqkkt1andqkkt4alleles were induced ont-chromatin. Each is a recessive embryonic lethal mutation. They fail to complement each other and are not complemented by the deletion,TtOrl. Homozygotes and hemizygotes die at 8–9·5 days gestation, but not at a single precise time. Because the classical quaking mutation complements the lethality of these new alleles, but they fail to complement its quaking phenotype (myelination defect), we conclude that the quaking+function is required for embryonic survival as well as for myelination.
Identification of two genes controlling kasugamycin resistance in the filamentous fungusPodospora anserina
Authors: Kieu-Ngoc An , Coppin-Raynal Evelyne 
Published: September 2009

SummaryWe have investigated the effect of the ribosome-targeted antibiotic kasugamycin (ksg) inPodospora anserina. While ksg inhibits both growth and sporulation, it has a stronger inhibitory effect on the sporulation process. It was previously reported that sporulation ofPodosporacould be impaired when ribosomes translate with a too high accuracy, and since ksg was demonstrated to increase the ribosomal accuracy inE. coli, we wondered whether it would act similarly inPodospora. As a first approach we have isolated two mutations at different loci,Ks1andKs2, that increase the resistance to ksg at the level of both growth and sporulation. InterestinglyKs1−1also confers a decreased resistance to paromomycin, which is a mistranslation inducer. Characterization ofKs1−1andKs2−1mutants suggests that they could be ribosomal mutants.
Geographical variation in house-fly (Musca domesticaL.) sex determinants within the British Isles
Authors: Denholm I. , Franco M. G. , Rubini P. G. , Vecchi M. 
Published: September 2009

SummaryGenetic and cytological analyses of house-flies collected from 12 pig-breeding farms throughout the British Isles demonstrated that the non-standard sex determination mechanism prevailing in South-East England, involving a dominant female determinant (F) and virtual homozygosity for a male determinant on theXchromosome (Xm, both males and females morphologicallyXX), was not typical of the country as a whole. Instead there was a gradual decrease in the frequency of F,Xmand a rarer male determinantMIII, and a concomitant increase in the standard male determiningYchromosome, on moving north, east and west of this region. Only the Scottish and probably the Irish populations were fully standard (XXfemalesXYmales), although one from the East Anglian coast in which non-standard determinants were rare was predominantly of this type. Populations from intermediate areas possessed complex multifactorial mechanisms in whichY, FXmandMIII coexisted. It is hypothesized that this radial cline in sex determinants, like the latitudinal cline known from mainland Europe, represents a transient polymorphism caused by the recent and continuing invasion of non-standard determinants into originally standard populations. The cause(s) of this apparently rapid evolutionary change, however, remain unclear.
Genetic analysis of theY-chromosome of the mouse: evidence for two loci affecting androgen metabolism
Authors: Jutley Jaswant K. , Stewart Alistair D. 
Published: September 2009

SummaryMale mice from congenic lines carryY-chromosomes derived from two pairs of inbred strains (CBA/FaCamSt and C57BL/FaSt; PHL/St and PHL-YH/St) on various genetic backgrounds were compared. Serum testosterone levels, and the response of target organs in castrated animals to graded doses of exogenous testerone propionate were measured. These comparisons produced evidence for twoY-chromosomal loci influencing androgen metabolism. One of these affects serum testosterone levels, with variant alleles on theY-chromosomes derived from the PHL and PHL-YH strains. The other locus influences the response to testosterone of target organs, most significantly seminal vesicle, and variant alleles are found in the CBA and C57 strains. The effects of both loci are modulated by the genetic background. The relationship of these loci to otherY-chromosomal loci in the mouse is briefly discussed.
A quantitative genetic analysis of fitness and its components inDrosophila melanogaster
Authors: Mackay Trudy F. C. 
Published: September 2009

SummaryForty-one third chromosomes extracted from a natural population ofDrosophila melanogasterwere assessed for net fitness and for the quantitative characters viability, net fertility, female productivity, male weight, abdominal bristle number, and sternopleural bristle number. Net homozygous and heterozygous fitness of the third chromosomes was estimated by competition against a marked balancer third chromosome. Average fitness of the homozygous lines relative to wild-type heterozygotes was 0·13, indicating substantial inbreeding depression for net fitness. All significant correlations of quantitative characters with fitness and with each other were high and positive. Homozygous fitness is strongly correlated with net fertility, viability, and female productivity, moderately associated with male weight, and not significantly associated with bristle traits. The combination of metric traits which best predicts homozygous fitness is the simple multiple of viability and female productivity. Heterozygous fitness is not correlated with homozygous fitness; furthermore, the relative contribution of metric traits to fitness in a heterozygous population is likely to be different from that deduced from homozygous lines. These observations are consistent with a model of genetic variation for fitness in natural populations caused by segregation of rare deleterious recessive alleles.
Effect of multiple copies ofrpoBCon the rate of RNA synthesis inEscherichia coli
Authors: Guzman Elena C. , Jimenez-Sanchez Alfonso 
Published: September 2009

SummaryThe cloning of therpoBandrpoCgenes in a high copy number vector inE. coliincreased the amount of the encoded gene products, the β and β′ subunits of RNA polymerase. However, this unexpectedly caused a 30–50% decrease in RNA synthetic activity which alternatively induced a reduction of growth rate and enlargement of cell size, and decreased the DNA replication time. The results can be explained by autogenous regulation of the RNA polymerase genes by the ββ′ subunits. A relation between the decrease in number of transcription units and the observed higher rate of movement of DNA replication forks is discussed.
Genetic divergence between transposable elements
Authors: Charlesworth Brian 
Published: September 2009

SummaryThe probabilities of genetic identity between different members of the same family of transposable elements in a randomly mating host population are determined, under the assumption of statistical equilibrium between neutral mutations, random genetic drift, transposition and unbiased gene conversion. The method allows for variation in numbers of copies of the element between individuals within the host population, and for dependence of the probability of identity between a pair of elements on the frequencies of elements at the sites from which they were drawn. It is shown that, for the range of parameters under which the approximations used are valid, the effects of gene conversion on identity probabilities are relatively small, as are the effects of copy number variation and variation between sites in element frequencies.
Transcription of rDNA insertions in bobbed mutants ofDrosophila melanogaster
Authors: Terracol Régine 
Published: September 2009

SummaryInDrosophila melanogastera large number of the genes coding for 18S and 28S rRNA are interrupted in the 28S region by insertions of two types. Ribosomal insertion transcripts were compared in wild-type and bobbed strains. We found that the level of insertion transcripts increased in bobbed mutants after deletion of 50% of INS−genes, and inversely decreased in revertants when more than 50% of wild-type levels. Among type II insertion transcripts we found a predominant 3·5 kb RNA, precisely of the most frequent insertion size. No primary insertion transcript has been found, although it could be undetected if very fast splicing leads to mature 28S occurs.
Absence of Y-chromosome introgression across the hybrid zone between Mus musculus domesticus and Mus musculus musculus
Authors: Vanlerberghe F. , Dod B. , Boursot P. , Bellis M. , Bonhomme F. 
Published: September 2009

SummaryA cloned Y-specific sequence (Bishop et al. 1985) was used as a diagnostic probe to distinguish between Mus musculus domesticus and Mus musculus musculusY-chromosomes. Analysis of the RFLPs obtained with genomic DNA isolated from wild mice caught along the contact zone between M. m. domesticus and M. m. musculus in Bulgaria and Denmark showed that the Y-chromosome flow between the two semi-species is very limited. The degree of Y-chromosome penetration was compared with that of seven diagnostic autosomal loci and the mitochondrial DNA. Breeding experiments showed that the lack of Y-chromosome introgression from one semispecies to the other was not due to a major hybrid breakdown. The results suggest that the disruption of differentiated co-adapted gene systems could play a role in limiting Y-introgression.
Map position of dysgenetic lens (dyl) locus on chromosome 4 in the mouse
Authors: Sanyal S. , van Nie R. , de Moes J. , Hawkins R. K. 
Published: September 2009

SummaryThe autosomal recessive gene, dysgenetic lens (dyl) in the mouse has been mapped on chromosome 4. Two- and three-point crosses involving b (brown) and Mup-1 (Major urinary protein-1) indicate the following gene order: dyl–b–Mup-1. The approximate distance between dyl and b is 12 and between dyl and Mup-1 is 20 cM.
The range of amino acids whose limitation activates general amino-acid control inNeurospora crassa
Authors: Barthelmess Ilse B. , Kolanus Johanna 
Published: September 2009

SummarySeveral amino-acid synthetic enzymes, belonging to arginie, glutamine, leucine, lysine and phenylalanine biosynthesis, respectively, were investigated under conditions of reduced availability of any one of 16 out of the 20 amino acids represented in proteins. The enzymes showed simultaneous derepression under each condition, albeit to different degrees. Derepression was abolished and the remaining basal enzyme levels reduced by mutations at thecpc-1locus which governs general amino-acid control inNeurospora. Glutamine synthetase was shown to be undercpc-1and additional controls. The evidence emphasizes the global nature of general amino-acid control.
Search for differences amongthaplotypes in distorter and responder genes
Authors: Lyon Mary F. 
Published: September 2009

SummaryTransmission ratio distortion due to the mousetcomplex is thought to be due to harmful effects oftrans-acting distorter genes acting on a responder, with thetcomplex form of the responder being relatively resistant to this harmful action of the distorters. Previous work had indicated that naturally occurringthaplotypes differed in their responders or in distorters lying near the responder, with the result that animals doubly heterozygous for two responder-carrying haplotypes transmitted these haplotypes unequally. In the present workthaplotypes could be divided into three types on the basis of their transmission when doubly heterozygous with the responder-carrying partial haplotypetlowH. The majority,t0,t6,tw1,tw2andtw73, were transmitted equally withtlowH, a second group, includingtw5and two haplotypes derived from it, were transmitted less frequently thantlowH, and the single member of a third group,t32, was transmitted in excess oftlowHThis last result suggests that the underlying differences are in the responder itself, rather than in the distorters. Search for differences amongthaplotypes in distorters produced some equivocal results possibly resulting from effects of genetic background. In particular, results of others suggesting presence of a fourth distorter,Tcd-4, were not confirmed.
The induction of tail malformations in trisomy 16 mouse fetuses heterozygous for thecurly tailrecessive gene
Authors: Crolla John Anthony , Lakeman Sarah Katrine , Seller Mary J. 
Published: September 2009

SummaryThe mouse mutantcurly tailis thought to be inherited as an autosomal recessive (ct/ct) with incomplete penetrance so that approximately 60% ofct/ctindividuals exhibit thecurly tail(CT) phenotype. By outcrossingct/ctwith mouse stock carrying specific heterozygous combinations of Robertsonian (Rb) chromosomes, trisomy 16 (Ts16) and Ts19 mouse fetuses (and their chromosomally balanced littermates) were derived which were heterozygous for thectgene. All of the Ts16 (ct/Rb;Rb) fetuses, studied between days 14–19 gestation had tail malformations, 86% of which were tail flexion defects (TFD) apparently very similar to thecurly tailphenotype. Neither Ts19 nor any of the chromosomally balanced (ct/Rb) littermates from both experimental crosses showed any type of tail or other spinal malformation. At the 27–29 somite stage of development, Ts16 (ct/Rb;Rb) fetuses did not show any significant delay in the closure of the posterior neuropore (PNP) compared with their littermate controls, suggesting that the tail malformation observed in Ts16 (ct/Rb;Rb) occur as a result of mechanisms which differ significantly from those thought to be responsible to causing thecurly tailmalformation.
Non-random chromosomal distribution ofAc-like sequences in inbred maize
Authors: Johns Mitrick A. , Fuerstenberg Susan I. , Hennelly Cheryl A. 
Published: September 2009

SummaryWe have searched for evidence of historical transpositions ofAc-like sequences in four standard maize lines using the recombinant-inbred mapping technique. Thirty restriction fragments were mapped usingEcoR I,EcoR V, andHindIII. The four inbreds contained 24 fragments which mapped to independent sites within each line; the other 6 fragments probably represented multiple mappings of the same element. Possible allelism between lines reduced this number to a minimum of 15 different sites containingAc-like elements. The distribution of these sequences does not fit the expected Poisson distribution; instead, an unusually large number of these elements were found on chromosome 4. The other sequences were scattered randomly throughout the genome. With few exceptions, each line had sequences in different locations; however, the overall distribution ofAc-like sequences was similar for all lines. The non-random distribution ofAc-like sequences suggests that they have undergone a limited number of transpositions in maize; the distribution is incompatible with either complete immobility or frequent transposition.
Genetic analysis of polymorphic proteins of the human malaria parasitePlasmodium falciparum
Authors: Fenton Brian , Walliker David 
Published: September 2009

SummaryFive polymorphic proteins, detected by two-dimensional electrophoresis, were analysed in the parents and progeny of a cross between two clones of the malaria parasitePlasmodium falciparum. The information obtained showed that different forms of each protein were determined by allelic variants of each respective gene. One protein was identified as the parasite enzyme adenosine deaminase. Recombinant parasites were produced at a higher than expected frequency.
Spontaneous induction of an homologous Robertsonian translocation, Rb(11.11) in a murine embryonic stem cell line
Authors: Crolla John Anthony , Brown David , Whittingham David G. 
Published: September 2009

SummaryKaryotype analysis of a series of established mouse embryonic stem cell (MESC) lines showed that the majority were aneuploid by the 7th and 9th passage and that all lines contained a single Robertsonian (Rb) translocation chromosome with a symmetrical, homologous, arm composition Rb(11.11). Although the chromosomal imbalance makes these MESC lines unsuitable for genetic manipulation in vitro and hence for subsequent production of transgenic animals, the spontaneous occurrence and stable retention of the homologous Rb(11.11) as the only metacentric chromosome in an otherwise all acrocentric karyotype, provides potentially useful cell lines for gene assignment and recombinant DNA studies.