bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetics of morphological differences and hybrid sterility betweenDrosophila sechelliaand its relatives
Authors: Coyne Jerry A. , Rux John , David Jean R. 
Published: September 2009

SummaryWe conducted classical genetic analysis of the difference in male genitalia and hybrid sterility between the island-dwelling sibling speciesDrosophila sechelliaandD. mauritiana. At least two loci (one on each autosome) are responsible for the genital difference, with the X chromosome having no significant effect. In contrast, male hybrid sterility is caused by at least four gene loci distributed among all major chromosomes, with those on the X chromosome having the largest effect.We also show that the large difference in ovariole number betweenD. sechelliaand its mainland relativeD. simulansis due to at least two gene substitutions, one on each major autosome. The X and the left arm of the second chromosome, however, have no significant effect on the character. This implies that the evolution of reduced ovariole number involved relatively few gene substitutions.These results extend previous findings that morphological differences betweenDrosophilaspecies are caused by genes distributed among all chromosomes, while hybrid sterility and inviability are due primarily to X-linked genes. Because strong X-effects on male sterility have been found in all three pairwise hybridizations amongD. simulans, D. sechelliaandD. mauritiana, these effects must have evolved at least twice independently.
Isolation and characterization of a cDNA clone corresponding to the mouse t-complex gene Tcp-1x
Authors: Dudley Keith , Shanahan Francis , Burtenshaw M. , Evans E. P. , Ruddy S. , Lyon M. F. 
Published: September 2009

SummaryThe mouse t complex on chromosome 17 is known to harbour many genes which have an important role in spermatogenesis. One of these, Tcp-1 has been cloned and shown to code for a protein probably essential for acrosome formation. During the isolation of a cDNA for Tcp-1 two other homologous sequences were recognized and described as Tcp-1x and Tcp-1y. In this paper we describe the isolation of a cDNA which has been shown by in situ hybridization to correspond to the Tcp-1x gene. Sequence analysis has confirmed that a 140 bp region of homology between Tcp-1 and Tcp-1x lies in the 3′ portion of both genes. Northern blotting has revealed that the Tcp-1x gene is expressed abundantly in liver where two transcripts are detectable and hybrid selection shows that the gene codes for a 37 kDa protein. A search of the DNA databases has failed to find any significant homology between Tcp-1x and any other sequences apart from Tcp-1.
The apparent selection on neutral marker loci in partially inbreeding populations
Authors: Charlesworth D. 
Published: September 2009

SummaryDeterministic computer calculations were used to investigate the effects on the fitnesses of genotypes at neutral loci that are caused by associations with several linked or unlinked selected loci, in partially self fertilizing populations. Both mutation to partially recessive alleles and heterozygote advantage at the selected loci were studied. In the heterozygote advantage models, either arbitrary linkage between all loci was modelled, with a single neutral locus, or many unlinked selected and neutral loci were modelled. Large apparent overdominance could be generated in all types of model studied. As has previously been suggested, these types of effect can explain the observed associations between fitness and heterozygosity in partially inbreeding populations. There were also apparent fitness differences between the genotypes at the neutral locus among the progeny produced by selfing, especially with linkage between the neutral and selected loci. There is thus no genotype-independent fitness value for these progeny. Marker based methods for estimating the relative fitness of selfed and outcrossed progeny assume equality of these fitnesses, and will therefore be inaccurate (with in most cases a bias towards overestimating the degree of inbreeding depression) when there is linkage between the neutral marker loci and loci determining fitness.
Multilocus models of inbreeding depression with synergistic selection and partial self-fertilization
Authors: Charlesworth B. , Morgan M. T. , Charlesworth D. 
Published: September 2009

SummaryMean fitness and inbreeding depression values in multi-locus models of the control of fitness were studied, using both a model of mutation to deleterious alleles, and a model of heterozygote advantage. Synergistic fitness interactions between loci were assumed, to find out if this more biologically plausible model altered the conclusions we obtained previously using a model of multiplicative interactions. Systems of unlinked loci were assumed. We used deterministic computer calculations, and approximations based on normal or Poisson theory. These approximations gave good agreement with the exact results for some regions of the parameter space. In the mutational model, we found that the effect of synergism was to lower the number of mutant alleles per individual, and thus to increase the mean fitness, compared with the multiplicative case. Inbreeding depression, however, was increased. Similar effects on mean fitness and inbreeding depression were found for the case of heterozygote advantage. For that model, the results were qualitatively similar to those previously obtained assuming multiplicativity. With the mutational load model, however, the mean fitness sometimes decreased, and the inbreeding depression increased, at high selfing rates, after declining as the selfing rate increased from zero. We also studied the behaviour of modifier alleles that changed the selfing rate, introduced into equilibrium populations. In general, the results were similar to those with the multiplicative model, but in some cases an ESS selfing rate, with selfing slightly below one, existed. Finally, we derive an approximate expression for the inbreeding depression in completely selfing populations. This depends only on the mutation rate and the dominance coefficient and can therefore be used to obtain estimates of the mutation rate to mildly deleterious alleles for plant species.
Differential susceptibility to a trematode parasite among genotypes of the Mytilus edulis/galloprovincialis complex
Authors: Coustau Christine , Renaud François , Maillard Claude , Pasteur Nicole , Delay Bernard 
Published: September 2009

SummaryWe show that parasitism by the trematode Prosorhynchus squamatus in parental and introgressed Mytilus edulis/galloprovincialis (Bivalvia) mussels occurs in individuals with a predominantly M. edulis genome. This result suggests that the restricted specificity of P. squamatus is dependent on genetic factor(s) present in M. edulis. Because of its strong pathogenic effects (i.e. total castration and possible death), this parasite may be a source of intense selection against M. edulis genomes when they are present in a site. As a consequence, it may favour the geographic extension of the M. galloprovincialis genome. Previous studies have indicated that, in hybrid zones, recombinant genotypes are more susceptible to parasitic infections than either parental genotype. We demonstrate that this is not the case for the M. edulis/M. galloprovincialis system, and that the parental genotype alone determines susceptibility.
Inheritance ofP-element regulation inDrosophila melanogaster
Authors: Raymond John D. , Ojala Todd A. , White Jennifer , Simmons Michael J. 
Published: September 2009

SummaryThe ability to repress P-element-induced gonadal dysgenesis was studied in 14 wild-type strains ofD. melanogasterderived from populations in the central and eastern United States. Females from each of these strains had a high ability to repress gonadal dysgenesis in their daughters. Reciprocal hybrids produced by crossing each of the wild-type strains with an M strain demonstrated that repression ability was determined by a complex mixture of chromosomal and cytoplasmic factors. Cytoplasmic transmission of repression ability was observed in all 14 strains and chromosomal transmission was observed in 12 of them. Genomic Southern blots indicated that four of the strains possessed a particular type of P element, called KP, which has been proposed to account for the chromosomal transmission of repression ability. However, in this study several of the strains that lacked KP elements exhibited as much chromosomal transmission of repression ability as the strains that had KP elements, suggesting that other kinds of P elements may be involved.
Fertility and viability at theSodlocus inDrosophila melanogaster: non-additive and asymmetric selection
Authors: Milosevic Mirjana , Moya Andrés , Ayala Francisco J. 
Published: September 2009

SummaryExperiments were designed to test inDrosophila melanogasterthe effect of mating type at theSodlocus on fertility and viability. The experiments show that fertility is neither additive (or multiplicative) nor symmetric, i.e. that the fertility of a mating type cannot be predicted from the average fertility of the two genotypes involved in the mating. There is no significant male x female interaction with respect or progeny viability; but the interaction is significant for productivity, i.e. when fertility and viability are jointly taken into account. There is overdominance with respect to female fertility, but not with respect to male fertility or to viability. There also is alloprocoptic selection with respect to fertility and with respect to productivity, i.e. matings between like homozygotes are less fertile and productive than matings between dissimilar homozygotes. Selection at theSodlocus yields stable polymorphic equilibria, with the frequency of theFallele predicted atP= 0·641 or 0·695, respectively for low and high larval density.
Restriction enzyme banding in Atlantic salmon (Salmo salar) and brown trout (Salmo trutta)
Authors: Hartley S. E. 
Published: September 2009

SummaryFixed metaphase chromosomes of brown trout and Atlantic salmon were digested with various restriction enzymes and stained with Giemsa. C band-like patterns were produced in both species by Alu I, Dde I, Hae III and Mbo I. Alu I revealed extra chromosome bands in brown trout which allowed identification of additional chromosome pairs, while the other three enzymes produced patterns identical to C banding. In the Atlantic salmon Dde I revealed telomeric bands at all telomeres in addition to the conventional C bands and all four enzymes had differential effects on the nucleolar organizer-associated heterochromatin. The relevance of these findings to chromosome identification and constitutive heterochromatin organization in salmonid fishes is discussed.
Genome size in Tribolium flour-beetles: inter- and intraspecific variation
Authors: Alvarez-Fuster Asunción , Juan Carlos , Petitpierre Eduard 
Published: September 2009

SummaryEight species of Tribolium and the related species Alphitobius diaperinus have been microdensitometrically analysed by measuring the nuclear content (1C value) of their Feuigenstained spermatids. The range of mean genome sizes goes from 0·157 pg in T. audax to 0·388 pg in T. brevicornis, including five significantly different groups of values. Also, in ail but one species of Tribolium significant intraspecific heterogeneity of genome size was found. The resemblances in genome size are not generally correlated with genetic homologies among species, but there is a highly significant correlation between genome size and spermatid size.
hobotransposable elements inDrosophila melanogasterandD. simulans
Authors: Boussy I. A. , Daniels S. B. 
Published: September 2009

SummaryGenomic patterns of occurrence of the transposable elementhoboare polymorphic in the sibling speciesDrosophila melanogasterandD. simulans. Most tested strains of both species have apparently complete (3·0 kb) and smallerhoboelements (H lines), but in both species some strains completely lack such canonicalhoboelements (E lines). The occurrence of H and E lines inD. simulansas well as inD. melanogasterimplies that an hypothesis of recent introduction in the latter species is inadequate to explain the phylogenetic occurrence ofhobo. Particular internally deleted elements, the approximately 1·5 kbTh1andTh2elements, are abundant in many lines ofD. melanogaster, and an analogous 1·1 kb internally deleted element,h del sim, is abundant in most lines ofD. simulans. Besides the canonicalhobosequences, both species (and their sibling speciesD. sechelliaandD. mauritiana) have manyhobo-hybridizing sequences per genome that do not appear to be closely related to the canonicalhobosequence.
AXenopus laeviscreatine kinase isozyme (CK-III/III) expressed preferentially in larval striated muscle: cDNA sequence, developmental expression and subcellular immunolocalization
Authors: Robert Jacques , Barandun Benjamin , Kobel Hans Rudolf 
Published: September 2009

SummaryA cDNA containing the nearly complete coding sequence of CK-III subunit ofX. laeviswas isolated, sequenced and further identified by comparing the tissue distribution of CK-III/III isozyme with that of its messenger. Comparison of CK-III deduced amino acid sequence with other CK sequences published reveals its close homology to M-CK subunits. Results using both cDNA probes and monoclonal antibodies specific for CK-III subunits indicate that the appearance and the accumulation of CK-III occur in parallel with myoblast differentiation. Moreover, subcellular immuno-histolocalization shows that CK-III/III isozyme is especially concentrated on larval myofibres at the level of A-bands.
Sandy: a new mouse model for platelet storage pool deficiency
Authors: Swank Richard T. , Sweet Hope O. , Davisson Muriel T. , Reddington Madonna , Novak Edward K. 
Published: September 2009

SummarySandy (sdy) is a mouse mutant with diluted pigmentation which recently arose in the DBA/2J strain. Genetic tests indicate it is caused by an autosomal recessive mutation on mouse Chromosome 13 near thecrandXtgenetic loci. This mutation is different genetically and hematologically from previously described mouse pigment mutations with storage pool deficiency (SPD). The sandy mutant has diluted pigmentation in both eyes and fur, is fully viable and has prolonged bleeding times. Platelet serotonin levels are extremely low although ATP dependent acidification activity of platelet organelles appears normal. Also, platelet dense granules are extremely reduced in number when analysed by electron microscopy of unfixed platelets. Platelets have abnormal uptake and flashing of the fluorescent dye mepacrine. Secretion of lysosomal enzymes from kidney and from thrombin-stimulated platelets is depressed 2- and 3-fold, and ceroid pigment is present in kidney. Sandy platelets have a reduced rate of aggregation induced by collagen. The sandy mutant has an unusually severe dense granule defect and thus may be an appropriate model for cases of human Hermansky-Pudlak syndrome with similarly extreme types of SPD. It represents the tenth example of a mouse mutant with simultaneous defects in melanosomes, lysosomes and/or platelet dense granules.
Further evidence for the importance of parental source of the Xce allele in X chromosome inactivation
Authors: Fowlis Deborah J. , Ansell John D. , Micklem H. Spedding 
Published: September 2009

SummaryUsing mice that were mosaics for bothXceand phosphoglycerate kinase (Pgk-1) alleles, we present further evidence that the parental source of the X chromosome may affect the probability of that X chromosome remaining active. The reciprocal cross differences in PGK-1 activity described here are intermediate between those published previously for other alleles ofXce.
Geographical patterns of gene frequencies in Italian populations ofOrnithogalum montanum(Liliaceae)
Authors: Pigliucci Massimo , Barbujani Guido 
Published: September 2009

SummaryGeographic variation was studied at 15 electrophoretic loci (40 alleles) in Italian populations ofOrnithogalum montanumCyr. ex Ten. (Liliaceae). Homogeneity of allele frequencies was assessed byGtests; gene-frequency patterns were described by spatial autocorrelation statistics; matrices of genetic and environmental distance were compared through a series of Mantel's tests, and the zones of highest overall gene-frequency change per unit distance (steep multi-locus clines, or genetic boundaries) were identified. Nineteen allele frequencies appear heterogeneously distributed, but only 3 of them show significant spatial structure. Only 2 allele frequencies are correlated with 1 environmental parameter. Large genetic differences are observed between spatially close populations. These findings support a model of differentiation in which the genetic relationships between isolates do not depend on their spatial distances, but reflect mainly population subdivision and restricted gene flow.
Heterochromatin as a factor affecting X-inactivation in interspecific female vole hybrids (Microtidae, Rodentia)
Authors: Zakian Suren M. , Nesterova Tatyana B. , Cheryaukene Olga V. , Bochkarev Michail N. 
Published: September 2009

SummaryFemale interspecific vole hybrids were examined for the expression of the G6PD and GALA genes on the X chromosomes. When one of the parents was a species with a heterochromatin block on the X, and the other parent was M. arvalis, without a heterochromatin block on the X, preferential expression of the genes of the M. arvalis X was consistently observed. When both parental species had heterochromatin on the X, the parental forms of G6PD and GALA were in about equal proportions in the hybrid females. The results of the cytological identification of the active and inactive X on the metaphase spreads in the hybrid females are in agreement with the biochemical results. It is suggested that the observed phenomenon may be due to a nonrandom inactivation of the X chromosome containing a heterochromatin block in crosses involving M. arvalis and by a random inactivation in those with both parents having heterochromatin blocks on the X chromosomes. These results support our previous suggestion that heterochromatin has an effect on X inactivation in female interspecific vole hybrids.
The Aedes aegypti genome: complexity and organization
Authors: Warren Ann M. , Crampton Julian M. 
Published: September 2009

SummaryWe describe the use of DNA reassociation kinetics to determine the total genome size and complexity together with the individual complexity and copy number of the single copy, middle repetitive and highly repeated DNA fractions of cell line and larval DNA from the mosquito, Aedes aegypti. The genome of Ae. aegypti is both large and complex, being one third the size of the human genome, and exhibits a short period interspersed repeat pattern. The implications of patterns of sequence arrangement and genome complexities for experiments aimed at isolating specific classes of DNA sequences, such as mobile genetic elements, are discussed.
The liver/erythrocyte pyruvate kinase gene complex [Pk-1] in the mouse: regulatory gene mutations
Authors: Fitton Lesley A. , Davidson Morag , Moore Karen J. , Charles Daniel J. , Pretsch Walter , Elston Robert C. , Bulfield Graham 
Published: September 2009

SummaryNine enzyme activity variants and one charge variant of liver/erythrocyte pyruvate kinase have been found amongst laboratory and wild mice. Four of the enzyme activity variants were previously reported to be caused by allelic differences in the structural gene,Pk-ls. Analysis of two putative regulatory gene mutations is now reported, both of which map at, or close to, the structural gene on chromosome 3. One of these mutations, in the inbred strain SWR, is tissue specific, affecting enzyme concentration in the liver but not the erythrocyte the other, which arose in a mutation experiment, doubles the enzyme concentration in both tissues. The organization and the nomenclature in the [Pk-1] gene complex are discussed and are compared with the organization of other comprehensively analysed gene complexes in the mouse.
Multiple amylase genes inDrosophila ananassaeand related species
Authors: Da Lage J.-L. , Lemeunier F. , Cariou M.-L. , David J. R. 
Published: September 2009

SummaryThe number and organization of amylase genes inDrosophila ananassaewere investigated through classical genetic methods andin situand filter hybridizations. At least four genes may be active inD. ananassae, organized as two independent pairs of closely linked copies on the 2L and 3L chromosomal arms. Several other species of theD. ananassaesubgroup were studied and show the same chromosomal locations, suggesting an ancient duplication event. However, the number ofAmycopies seems to be higher in theD. ananassaemultigene family, and there is a striking intraspecific molecular differentiation.
Chromosomal localisation of the mouse and human peripherin genes
Authors: Moncla Anne , Landon Françoise , Mattei Marie-Genevieve , Portier Marie-Madeleine 
Published: September 2009

SummaryUsing a mouse cDNA probe encoding for the major part of peripherin, a type III intermediate filament protein, we have assigned, byin situhybridization, the mouse and human peripherin genes,Prph, to the E–F region of chromosome 15 and to the q12–q13 region of chromosome 12, respectively. These regions are known as homologous chromosomal segments containing other intermediate filament genes (keratins) and also other genes which could be co-ordinately regulated.
Chromosomal location of a barley malt endopeptidase gene
Authors: Guerin J. R. , Lance R. C. M. , Wallace W. 
Published: September 2009

SummaryExtracts of disomic wheat-barley addition lines were tested for the presence of a barley malt endopeptidase (MEP-1) by employing isoelectric focusing (IEF) and western blotting. The blots were probed with polyclonal antibodies raised against MEP-1 purified from the endosperms of 5-day-old germinated barley seedlings. The endopeptidase was detected in the Betzes barley cultivar and the addition line containing the full genome of the wheat cultivar Chinese Spring plus a chromosome 3 pair from Betzes barley. The endopeptidase was not expressed in Chinese Spring nor the addition lines containing other Betzes chromosome pairs. The endopeptidase was detected in a ditelosomic addition line containing the long arm of Betzes chromosome 3. We have concluded that the gene coding for MEP-1 (Cep-B) is located on the long arm of Betzes chromosome 3.
The segmentation generuntis needed to activateSex-lethal, a gene that controls sex determination and dosage compensation inDrosophila
Authors: Torres Miguel , Sanchez Lucas 
Published: September 2009

SummaryInDrosophila, sex is determined by the relative number of X chromosomes to autosomal sets (X: A ratio). The amount of products from several X-linked genes, calledsisterlesselements, is used to indicate toSex-lethalthe relative number of X chromosomes present in the cell. In response to the X: A signal,Sex-lethalis activated in females but remains inactive in males, being responsible for the control of both sex determination and dosage compensation. Here we find that the X-linked segmentation generuntplays a role in this process. Reduced function of runt results in femalespecific lethality and sexual transformation of XX animals that are heterozygous forSxlorsisloss-of-function mutations. These interactions are suppressed bySxlMI, a mutation that constitutively expresses femaleSex-lethalfunctions, and occur at the time when the X: A signal determinesSex-lethalactivity. Moreover, the presence of a loss-of-functionruntmutation masculinizes triploid intersexes. On the other hand,runtduplications cause a reduction in male viability by ectopic activation ofSex-lethal. We conclude thatruntis needed for the initial step ofSex-lethalactivation, but does not have a major role as an X-counting element.