Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| sex-ratio meiotic drive in drosophila simulans is related to equational nondisjunction of the y chromosome. | the sex-ratio trait, an example of naturally occurring x-linked meiotic drive, has been reported in a dozen drosophila species. males carrying a sex-ratio x chromosome produce an excess of female offspring caused by a deficiency of y-bearing sperm. in drosophila simulans, such males produce approximately 70-90% female offspring, and 15-30% of the male offspring are sterile. here, we investigate the cytological basis of the drive in this species. we show that the sex-ratio trait is associated wit ... | 2000 | 10628983 |
| location of shfr, a new gene that rescues hybrid female viability in crosses between drosophila simulans females and d. melanogaster males. | as a rule, progeny of crosses between drosophila simulans females and d. melanogaster males are formed by sterile males, because females die as embryos. however, populations of these species have been found that produce a certain frequency of viable hybrid females. we have found that 94% of the females of a d. simulans population from tel aviv gave hybrid progenies with both sexes. the segregation of phenotypes with different rescue success adjusts to the action of a single, dominant, zygotic-ac ... | 2000 | 10886378 |
| developmental expression of the 412 retrotransposon in natural populations of d. melanogaster and d. simulans. | we analysed the pattern of expression of retrotransposon 412 through developmental stages in various populations of drosophila simulans and d. melanogaster differing in 412 copy number. we found that the 412 expression pattern varied greatly between populations of both species, indicating that such patterns were not entirely species-specific. in d. simulans, total transcripts increased with number of 412 copies in the chromosomes when this number was low, and then decreased for high copy numbers ... | 2000 | 11204969 |
| the population genetics of the origin and divergence of the drosophila simulans complex species. | the origins and divergence of drosophila simulans and close relatives d. mauritiana and d. sechellia were examined using the patterns of dna sequence variation found within and between species at 14 different genes. d. sechellia consistently revealed low levels of polymorphism, and genes from d. sechellia have accumulated mutations at a rate that is approximately 50% higher than the same genes from d. simulans. at synonymous sites, d. sechellia has experienced a significant excess of unpreferred ... | 2000 | 11102384 |
| offsetting effects of wolbachia infection and heat shock on sperm production in drosophila simulans: analyses of fecundity, fertility and accessory gland proteins. | infection in drosophila simulans with the endocellular symbiont wolbachia pipientis results in egg lethality caused by failure to properly initiate diploid development (cytoplasmic incompatibility, ci). the relationship between wolbachia infection and reproductive factors influencing male fitness has not been well examined. here we compare infected and uninfected strains of d. simulans for (1) sperm production, (2) male fertility, and (3) the transfer and processing of two accessory gland protei ... | 2000 | 10790392 |
| comparative genomics of mitochondrial dna in drosophila simulans. | the current study compares the nucleotide variation among 22 complete mitochondrial genomes of the three distinct drosophila simulans haplotypes with intron 1 of the alcohol dehydrogenase-related locus. this is the first study to investigate the sequence variation of multiple complete mitochondrial genomes within distinct mitochondrial haplotypes of a single species. patterns of variation suggest distinct forces are influencing the evolution of mitochondrial dna (mtdna) and autosomal dna in d. s ... | 2000 | 10903373 |
| high copy numbers of multiple transposable element families in an australian population of drosophila simulans. | sudden mobilization of transposable elements in drosophila is a well-reported phenomenon but one that usually affects no more than a few elements (one to four). we report here the existence of a d. simulans natural population (canberra) from australia, which had high copy numbers for various transposable elements (transposons, ltr retrotransposons and non-ltr retrotransposons). the impact of transposable elements on the host genome and populations is discussed. | 2000 | 11006639 |
| wolbachia segregation rate in drosophila simulans naturally bi-infected cytoplasmic lineages. | wolbachia are maternally transmitted endocellular bacteria infecting several arthropod species. in order to study wolbachia segregation rate, drosophila simulans females from an indo-pacific population (seychelles) bi-infected by the two wolbachia variants wha and wno were backcrossed to uninfected males in two conditions. in the first case, seychelles males from a stock cured from its wolbachia by tetracycline treatment were used. in the second case, the males came from a naturally uninfected t ... | 2000 | 11012722 |
| expression of cytoplasmic incompatibility in drosophila simulans and its impact on infection frequencies and distribution of wolbachia pipientis. | the aim of this study is to examine the expression of cytoplasmic incompatibility and investigate the distribution and population frequencies of wolbachia pipientis strains in drosophila simulans. nucleotide sequence data from 16s rdna and a wolbachia surface protein coding sequence and cytoplasmic incompatibility assays identify four distinct wolbachia strains: wha, wri, wma, and wau. the levels of cytoplasmic incompatibility between six lines carrying these strains of bacteria and three contro ... | 2000 | 11108593 |
| wolbachia neither induces nor suppresses transcripts encoding antimicrobial peptides. | wolbachia are intracellular maternally inherited microorganisms that are associated with reproductive abnormalities such as cytoplasmic incompatibility (ci), feminization and parthenogenesis in the various arthropod species they infect. surveys indicate that these bacteria infect more than 16% of all insect species as well as isopods, mites and nematodes, making wolbachia one of the most ubiquitous parasites yet described. however, nothing is known about the interactions of this bacterium with t ... | 2000 | 11122472 |
| mechanisms of conspecific sperm precedence in drosophila. | the postmating, prezygotic isolating mechanism known as conspecific sperm precedence (csp) may play an important role in speciation, and understanding the mechanism of csp is important in reconstructing its evolution. when a drosophila simulans female mates with both a d. simulans male and a d. mauritiana male, the vast majority of her progeny are fathered by d. simulans, regardless of the order of mating. the dearth of hybrid progeny does not result from inviability of eggs fertilized by hetero ... | 2000 | 11209779 |
| the phylogeny of closely related species as revealed by the genealogy of a speciation gene, odysseus. | molecular differentiation between races or closely related species is often incongruent with the reproductive divergence of the taxa of interest. shared ancient polymorphism and/or introgression during secondary contact may be responsible for the incongruence. at loci contributing to speciation, these two complications should be minimized (1, 2); hence, their variation may more faithfully reflect the history of the species' reproductive differentiation. in this study, we analyzed dna polymorphis ... | 2000 | 10779562 |
| nucleotide variation at the yellow gene region is not reduced in drosophila subobscura: a study in relation to chromosomal polymorphism. | in contrast to drosophila melanogaster and drosophila simulans, the yellow (y) gene region of drosophila subobscura is not located in a region with a strong reduction in recombination. in addition, this gene maps very close to the breakpoints of different inversions that segregate as polymorphic in natural populations of d. subobscura. therefore, levels of variation at the y gene region in this species relative to those found in d. melanogaster and d. simulans may be affected not only by the cha ... | 2000 | 11110911 |
| characterization of defects in adult germline development and oogenesis of sterile and rescued female hybrids in crosses between drosophila simulans and drosophila melanogaster. | crosses between drosophila melanogaster and d. simulans normally result in progeny that are either inviable or sterile. recent discovery of strains that rescue these inviability and sterility phenotypes has made it possible to study the developmental basis of reproductive isolation between these two species in greater detail. by producing both rescued and unrescued hybrids and examining the protein product staining patterns of genes known to be involved in early germline development and gametoge ... | 2000 | 11069139 |
| nonrandom mating in drosophila melanogaster laboratory populations derived from closely adjacent ecologically contrasting slopes at "evolution canyon". | ecological differentiation of natural populations of drosophila melanogaster, drosophila simulans, and another drosophilid, zaprionus tuberculatus, in "evolution canyon," mount carmel, israel, is well established. the fitness complex of d. melanogaster includes oviposition temperature preferences, tolerance to high temperature, drought stress and starvation, and different longevity patterns. this remarkable differentiation has evolved despite small interslope distances (only 100-400 m), within e ... | 2000 | 11050149 |
| variations of male cuticular hydrocarbons with geoclimatic variables: an adaptative mechanism in drosophila melanogaster? | 7-tricosene (7t) and 7-pentacosene (7p) are the major components of cuticular hydrocarbons in drosophila simulans and d. melanogaster males. a chemical study of 16 isofemale lines of d. melanogaster sampled at the first and eighth generations in laboratory conditions showed the stability of chromatographical profiles. then a large scale study of male 7t/7p polymorphism was performed with 85 populations of d. melanogaster and 29 of d. simulans collected all over the world. there were significant ... | 2000 | 11678502 |
| high density of long dinucleotide microsatellites in drosophila subobscura. | we isolated 96 dinucleotide repeats with five or more tandemly repeated units from a subgenomic drosophila subobscura library. the mean repeat unit length of microsatellite clones in d. subobscura is 15, higher than that observed in other drosophila species. population variation was assayed in 32-40 chromosomes from barcelona, spain, using 18 randomly chosen microsatellite loci. positive correlation between measures of variation and perfect repeat length measures (mean size, most common, and lon ... | 2000 | 10908646 |
| reduced x-linked nucleotide polymorphism in drosophila simulans. | population genetic theory predicts that selectively driven changes of allele frequency for both beneficial and deleterious mutants reduce polymorphism at tightly linked sites. all else being equal, these reductions in polymorphism are expected to be greater when recombination rates are lower. therefore, the empirical observation of a positive correlation between recombination rates and amounts of dna polymorphism across the drosophila melanogaster genome can be explained by two very different ty ... | 2000 | 10823947 |
| the evolution of an alpha-esterase pseudogene inactivated in the drosophila melanogaster lineage. | previous analyses of the alpha-esterase cluster of drosophila melanogaster revealed 10 active genes and the dmalphae4a-psi pseudogene. here, we reconstruct the evolution of the pseudogene from the sequences of 12 alleles from widely scattered d. melanogaster populations and single alleles from drosophila simulans and drosophila yakuba. all of the dmalphae4a-psi alleles contain numerous inactivating mutations, suggesting that pseudogene alleles are fixed in natural populations. several lines of e ... | 2000 | 10742048 |
| genetic analysis of speciation by means of introgression into drosophila melanogaster. | in the last decade, the genetic basis of reproductive isolation has been shown to be surprisingly polygenic, and yet even the most efficient system currently in use could lend itself to molecular analysis only in highly selected cases. by extending the recent discovery of fertility rescue between drosophila melanogaster and drosophila simulans, we show that this hybridization can permit systematic and precise delineation of the genetic and molecular basis of speciation. in a region of 5% of the ... | 2000 | 10706624 |
| molecular evolutionary analysis of a histone gene repeating unit from drosophila simulans. | a repeating unit of the histone gene cluster from drosophila simulans containing the h1, h2a, h2b and h4 genes (the h3 gene region has already been analyzed) was cloned and analyzed. a nucleotide sequence of about 4.6 kbp was determined to study the nucleotide divergence and molecular evolution of the histone gene cluster. comparison of the structure and nucleotide sequence with those of drosophila melanogaster showed that the four histone genes were located at identical positions and in the sam ... | 2001 | 11922104 |
| contrasting patterns of x-linked and autosomal nucleotide variation in drosophila melanogaster and drosophila simulans. | surveys of molecular variation in drosophila melanogaster and drosophila simulans have suggested that diversity outside of africa is a subset of that within africa. it has been argued that reduced levels of diversity in non-african populations reflect a population bottleneck, adaptation to temperate climates, or both. here, i summarize the available single-nucleotide polymorphism data for both species. a simple "out of africa" bottleneck scenario is consistent with geographic patterns for loci o ... | 2001 | 11230529 |
| recombination and the frequency spectrum in drosophila melanogaster and drosophila simulans. | most "tests of neutrality" assess whether particular data sets depart from the predictions of a standard neutral model with no recombination. for drosophila, where nuclear polymorphism data routinely show evidence of genetic exchange, the assumption of no recombination is often unrealistic. in addition, while conservative, this assumption is made at the cost of a great loss in power. perhaps as a result, tests of the frequency spectrum based on zero recombination suggest an adequate fit of droso ... | 2001 | 11230530 |
| circadian rhythms of female mating activity governed by clock genes in drosophila. | the physiological and behavioral activities of many animals are restricted to specific times of the day. the daily fluctuation in the mating activity of some insects is controlled by an endogenous clock, but the genetic mechanism that controls it remains unknown. here we demonstrate that wild-type drosophila melanogaster display a robust circadian rhythm in the mating activity, and that these rhythms are abolished in period- or timeless-null mutant flies (per(01) and tim(01)). circadian rhythms ... | 2001 | 11470898 |
| the sibling species drosophila melanogaster and drosophila simulans differ in the expression profile of glutathione s-transferases. | two major forms of glutathione s-transferase are known in drosophila melanogaster: gst d and gst 2. in the present paper we report the existence of a third major form of glutathione s-transferase in drosophila simulans. induction with phenobarbital revealed a different regulation of gst between these species. despite the fact that these two species are closely related, there was a difference in the expression profile of the enzyme implicated in the detoxification system, suggesting variations in ... | 2001 | 11435138 |
| evolutionary est analysis identifies rapidly evolving male reproductive proteins in drosophila. | sequence comparisons of genomes or expressed sequence tags (ests) from related organisms provide insight into functional conservation and diversification. we compare the sequences of ests from the male accessory gland of drosophila simulans to their orthologs in its close relative drosophila melanogaster, and demonstrate rapid divergence of many of these reproductive genes. nineteen ( approximately 11%) of 176 independent genes identified in the est screen contain protein-coding regions with an ... | 2001 | 11404480 |
| patterns of dna sequence variation suggest the recent action of positive selection in the janus-ocnus region of drosophila simulans. | levels of nucleotide polymorphism in three paralogous drosophila simulans genes, janusa (jana), janusb (janb), and ocnus (ocn), were surveyed by dna sequencing. the three genes lie in tandem within a 2.5-kb region of chromosome arm 3r. in a sample of eight alleles from a worldwide distribution we found a significant departure from neutrality by several statistical tests. the most striking feature of this sample was that in a 1.7-kb region containing the jana and janb genes, 30 out of 31 segregat ... | 2001 | 11606541 |
| dynamics of r1 and r2 elements in the rdna locus of drosophila simulans. | the mobile elements r1 and r2 insert specifically into the rrna gene locus (rdna locus) of arthropods, a locus known to undergo concerted evolution, the recombinational processes that preserve the sequence homogeneity of all repeats. to monitor how rapidly individual r1 and r2 insertions are turned over in the rdna locus by these processes, we have taken advantage of the many 5' truncation variants that are generated during the target-primed reverse transcription mechanism used by these non-ltr ... | 2001 | 11514447 |
| sex-ratio segregation distortion associated with reproductive isolation in drosophila. | sex-ratio distortion is the most common form of non-mendelian segregation observed in natural populations. it may occur even more frequently than direct observations suggest, because the dysgenic population consequences of a biased sex ratio are expected to result in the rapid evolution of suppressors, resulting in suppressed or "cryptic" segregation distortion. here we report evidence for cryptic sex-ratio distortion that was discovered by introgressing segments of the genome of drosophila maur ... | 2001 | 11687638 |
| wolbachia-mediated sperm modification is dependent on the host genotype in drosophila. | estimates of wolbachia density in the eggs, testes and whole flies of drosophilid hosts have been unable to predict the lack of cytoplasmic incompatibility (ci) expression in so-called mod(-) variants. consequently, the working hypothesis has been that ci expression, although related to wolbachia density, is also governed by unknown factors that are influenced by both host and bacterial genomes. here, we compare the behaviour of the mod(-) over-replicating wolbachia popcorn strain in its native ... | 2001 | 11749711 |
| two novel pao-like retrotransposons (kamikaze and yamato) from the silkworm species bombyx mori and b. mandarina: common structural features of pao-like elements. | to characterize the structural features common to pao-like retrotransposons, we analyzed two lambda phage clones which contain the pao-like elements from the silkworm species bombyx mori and b. mandarinia, and copies of pao itself and ninja of drosophila simulans, amplified by pcr. we previously identified two randomly amplified polymorphic dnas (rapds), w-kamikaze and w-yamato, from b. mori and b. mandarina, which are part of two novel pao-like retrotransposons, kamikaze and yamato, respectivel ... | 2001 | 11361350 |
| dna variation at the rp49 gene region of drosophila simulans: evolutionary inferences from an unusual haplotype structure. | an approximately 1.3-kb region including the rp49 gene plus its 5' and 3' flanking regions was sequenced in 24 lines of drosophila simulans (10 from spain and 14 from mozambique). fifty-four nucleotide and 8 length polymorphisms were detected. all nucleotide polymorphisms were silent: 52 in noncoding regions and 2 at synonymous sites in the coding region. estimated silent nucleotide diversity was similar in both populations (pi = 0.016, for the total sample). nucleotide variation revealed an unu ... | 2001 | 11454763 |
| the frequency distribution of nucleotide variation in drosophila simulans. | patterns of codon bias in drosophila suggest that silent mutations can be classified into two types: unpreferred (slightly deleterious) and preferred (slightly beneficial). results of previous analyses of polymorphism and divergence in drosophila simulans were interpreted as supporting a mutation-selection-drift model in which slightly deleterious, silent mutants make significantly greater contributions to polymorphism than to divergence. frequencies of unpreferred polymorphisms were inferred to ... | 2001 | 11420372 |
| the y chromosomes of drosophila simulans are highly polymorphic for their ability to suppress sex-ratio drive. | the sex-ratio trait, known in several species of drosophila including d. simulans, results from meiotic drive of the x chromosome against the y. males that carry a sex-ratio x chromosome produce strongly female-biased progeny. in d. simulans, drive suppressors have evolved on the y chromosome and on the autosomes. both the frequency of sex-ratio x and the strength of the total drive suppression (y-linked and autosomal) vary widely among geographic populations of this worldwide species. we have i ... | 2001 | 11392391 |
| cryptic reproductive isolation in the drosophila simulans species complex. | forms of reproductive isolation that act after copulation but before fertilization are potentially important components of speciation, but are studied only infrequently. we examined postmating, prezygotic reproductive isolation in three hybridizations within the drosophila simulans species complex. we allowed females to mate only once, observed and timed all copulations, dissected a subset of the females to track the storage and retention of sperm, examined the number and hatchability of eggs la ... | 2001 | 11263748 |
| adaptive protein evolution in drosophila. | for over 30 years a central question in molecular evolution has been whether natural selection plays a substantial role in evolution at the dna sequence level. evidence has accumulated over the last decade that adaptive evolution does occur at the protein level, but it has remained unclear how prevalent adaptive evolution is. here we present a simple method by which the number of adaptive substitutions can be estimated and apply it to data from drosophila simulans and d. yakuba. we estimate that ... | 2002 | 11875568 |
| protein variation in drosophila simulans, and comparison of genes from centromeric versus noncentromeric regions of chromosome 3. | 2002 | 11801748 | |
| genomic effects of nucleotide substitutions in drosophila simulans. | selective fixation of beneficial mutations reduces levels of linked, neutral variation. the magnitude of this "hitchhiking effect" is determined by the strength of selection and the recombination rate between selected and neutral sites. thus, depending on the values of these parameters and the frequency with which directional selection occurs, the genomic scale over which directional selection reduces levels of linked variation may vary widely. here we present a permutation-based analysis of nuc ... | 2002 | 12524346 |
| sex-ratio drive in drosophila simulans: variation in segregation ratio of x chromosomes from a natural population. | the sex-ratio trait that exists in a dozen drosophila species is a case of naturally occurring x chromosome drive that causes males to produce female-biased progeny. autosomal and y polymorphism for suppressors are known to cause variation in drive expression, but the x chromosome polymorphism has never been thoroughly investigated. we characterized 41 x chromosomes from a natural population of drosophila simulans that had been transferred to a suppressor-free genetic background. we found two cl ... | 2002 | 12454068 |
| tissue-specificity of 412 retrotransposon expression in drosophila simulans and d. melanogaster. | we analyse the expression of the retrotransposon 412 in the soma, testes, and ovaries in populations of drosophila simulans and d. melanogaster, using rt-pcr and in situ hybridization. we find that expression of 412 is highly variable in the soma, confirming previous findings based on northern blots. no 412rna is detected in the ovaries by either in situ hybridization or rt-pcr, in any population of either species. transcripts are, however, detected in the male germline, which show a very charac ... | 2002 | 12242639 |
| testing models of selection and demography in drosophila simulans. | we analyze patterns of nucleotide variability at 15 x-linked loci and 14 autosomal loci from a north american population of drosophila simulans. we show that there is significantly more linkage disequilibrium on the x chromosome than on chromosome arm 3r and much more linkage disequilibrium on both chromosomes than expected from estimates of recombination rates, mutation rates, and levels of diversity. to explore what types of evolutionary models might explain this observation, we examine a mode ... | 2002 | 12242234 |
| an introgression approach to mapping differences in mating success and sperm competitive ability in drosophila simulans and d. sechellia. | the progeny of drosophila females doubly-mated to males from the same and a closely related species are mostly sired by conspecific males. we examined the genetic basis for conspecific mating preference and sperm precedence by using 186 drosophila lines in which random chromosomal fragments of d. sechellia were introgressed into d. simulans. sperm competition was measured for each of these lines by crossing ebony d. simulans female with ebony d. simulans males followed by wild-type males from th ... | 2002 | 11974604 |
| the distribution and proliferation of the intracellular bacteria wolbachia during spermatogenesis in drosophila. | wolbachia is a cytoplasmically inherited alpha-proteobacterium found in a wide range of host arthropod and nematode taxa. wolbachia infection in drosophila is closely associated with the expression of a unique form of post-fertilization lethality termed cytoplasmic incompatibility (ci). this form of incompatibility is only expressed by infected males suggesting that wolbachia exerts its effect during spermatogenesis. the growth and distribution of wolbachia throughout sperm development in indivi ... | 2002 | 11804774 |
| recurrent evolution of dna-binding motifs in the drosophila centromeric histone. | all eukaryotes contain centromere-specific histone h3 variants (cenh3s), which replace h3 in centromeric chromatin. we have previously documented the adaptive evolution of the drosophila cenh3 (cid) in comparisons of drosophila melanogaster and drosophila simulans, a divergence of approximately 2.5 million years. we have proposed that rapidly changing centromeric dna may be driving cenh3's altered dna-binding specificity. here, we compare cid sequences from a phylogenetically broader group of dr ... | 2002 | 11805302 |
| characterization of wolbachia host cell range via the in vitro establishment of infections. | maternally transmitted bacteria of the genus wolbachia are obligate, intracellular symbionts that are frequently found in insects and cause a diverse array of reproductive manipulations, including cytoplasmic incompatibility, male killing, parthenogenesis, and feminization. despite the existence of a broad range of scientific interest, many aspects of wolbachia research have been limited to laboratories with insect-rearing facilities. the inability to culture these bacteria outside of the invert ... | 2002 | 11823204 |
| wolbachia density and virulence attenuation after transfer into a novel host. | the factors that control replication rate of the intracellular bacterium wolbachia pipientis in its insect hosts are unknown and difficult to explore, given the complex interaction of symbiont and host genotypes. using a strain of wolbachia that is known to over-replicate and shorten the lifespan of its drosophila melanogaster host, we have tracked the evolution of replication control in both somatic and reproductive tissues in a novel host/wolbachia association. after transinfection (the transf ... | 2002 | 11880639 |
| dynamics of double and single wolbachia infections in drosophila simulans from new caledonia. | the bacterial symbiont wolbachia can cause cytoplasmic incompatibility in drosophila simulans flies: if an infected male mates with an uninfected female, or a female with a different strain of wolbachia, there can be a dramatic reduction in the number of viable eggs produced. here we explore the dynamics associated with double and single wolbachia infections in new caledonia. doubly infected females were compatible with all males in the population, explaining the high proportion of doubly infect ... | 2002 | 11920119 |
| spatially explicit models of turelli-hoffmann wolbachia invasive wave fronts. | this paper examines different mathematical models of insect dispersal and infection spread and compares these with field data. reaction-diffusion and integro-difference equation models are used to model the spatio-temporal spread of wolbachia in drosophila simulans populations. the models include cytoplasmic incompatibility between infected females and uninfected males that creates a threshold density, similar to an allee effect, preventing increase from low incidence of infection in the host po ... | 2002 | 12051989 |
| evolution of wolbachia-induced cytoplasmic incompatibility in drosophila simulans and d. sechellia. | the intracellular bacterium wolbachia invades arthropod host populations through various mechanisms, the most common of which being cytoplasmic incompatibility (ci). ci involves elevated embryo mortality when infected males mate with uninfected females or females infected with different, incompatible wolbachia strains. the present study focuses on this phenomenon in two drosophila species: d. simulans and d. sechellia. drosophila simulans populations are infected by several wolbachia strains, in ... | 2002 | 12389718 |
| cloning and characterization of a gene encoding glutathione-regulated potassium-efflux system protein kefkl from the endosymbiont wolbachia. | the maternally inherited intracellular symbiont wolbachia is well known for inducing a variety of reproductive and developmental abnormalities in the diverse arthropod hosts it infects. it has been implicated in causing cytoplasmic incompatibility (ci), parthenogenesis, feminization of genetic males and male killing in different hosts. however, the molecular mechanisms by which this fastidious bacterium causes these abnormalities have not yet been determined. in our study, representational diffe ... | 2002 | 12652910 |
| divergence of mitochondrial dna is not corroborated by nuclear dna, morphology, or behavior in drosophila simulans. | we ask whether the observed mitochondrial dna (mtdna) population subdivision of drosophila simulans is indicative of organismal structure or of specific processes acting on the mitochondrial genome. factors either intrinsic or extrinsic to the host genome may influence the evolutionary dynamics of mtdna. potential intrinsic factors include adaptation of the mitochondrial genome and of nucleomitochondrial gene complexes specific to the local environment. an extrinsic force that has been shown to ... | 2002 | 11989683 |
| molecular evolution of the est-6 gene in drosophila melanogaster: contrasting patterns of dna variability in adjacent functional regions. | we have investigated nucleotide polymorphism at the esterase 6 gene (est-6) gene, including the complete coding region (1686 bp), as well as the 5'-flanking (1183 bp) and 3'-flanking (193 bp) regions of the gene, in 30 strains of drosophila melanogaster and in one strain of drosophila simulans. the level of silent variation is similar in the coding and in the 3'-flanking region, but smaller in the 5'-flanking region. strong linkage disequilibrium occurs within each region; and also, although les ... | 2002 | 12034506 |
| [dna from drosophila melanogaster region 61c7/c8 has high evolution rate]. | the results of a comparative study of cloned dna fragments of drosophila simulans, d. mauritiana, d. teissieri, and d. erecta are presented. the fragments were amplified in pcr with primers specified to the region of d. melanogaster interband 61c7/c8. the uniqueness of all cloned fragments in the genomes of these species was confirmed. a comparative analysis of nucleotide sequences revealed that the rate of evolution of dna from d. melanogaster interband 61c7/c8 is close to the rate of neutral e ... | 2002 | 12018164 |
| linkage limits the power of natural selection in drosophila. | population genetic theory shows that the efficacy of natural selection is limited by linkage-selection at one site interferes with selection at linked sites. such interference slows adaptation in asexual genomes and may explain the evolutionary advantage of sex. here, we test for two signatures of constraint caused by linkage in a sexual genome, by using sequence data from 255 drosophila melanogaster and drosophila simulans loci. we find that (i) the rate of protein adaptation is reduced in regi ... | 2002 | 12370444 |
| testing the neutral theory of molecular evolution with genomic data from drosophila. | although positive selection has been detected in many genes, its overall contribution to protein evolution is debatable. if the bulk of molecular evolution is neutral, then the ratio of amino-acid (a) to synonymous (s) polymorphism should, on average, equal that of divergence. a comparison of the a/s ratio of polymorphism in drosophila melanogaster with that of divergence from drosophila simulans shows that the a/s ratio of divergence is twice as high---a difference that is often attributed to p ... | 2002 | 11875569 |
| variable modes of inheritance of morphometrical traits in hybrids between drosophila melanogaster and drosophila simulans. | we investigated body-size inheritance in interspecific sterile hybrids by crossing a drosophila simulans strain with 13 strains of drosophila melanogaster, which were of various origins and chosen for their broad range of genetic variation. a highly significant parent-offspring correlation was observed, showing that the d. melanogaster genes for size are still expressed in a hybrid background. superimposed on to this additive inheritance, the size of hybrids was always less than the mid-parent v ... | 2002 | 11798427 |
| evolution of genome size in drosophila. is the invader's genome being invaded by transposable elements? | genome size varies considerably between species, and transposable elements (tes) are known to play an important role in this variability. however, it is far from clear whether tes are involved in genome size differences between populations within a given species. we show here that in drosophila melanogaster and drosophila simulans the size of the genome varies among populations and is correlated with the te copy number on the chromosome arms. the tes embedded within the heterochromatin do not se ... | 2002 | 12082134 |
| [multiple allelism of the net gene in drosophila melanogaster and drosophila simulans]. | the net gene mutations are known to cause abnormal pattern of veining in all wing regions except for the first posterior cells. in natural populations of drosophila melanogaster, the net alleles were identified, which differ in phenotypic expression from standard mutations. the mutants net-extra-analis from a population belokurikha-2000 have only a single additional vein in the third posterior cell. a line from chernobyl-1986 population have another nontypical allele netch86 and shows a lower de ... | 2003 | 14964828 |
| genetics of drosophila simulans male mating discrimination in crosses with d. melanogaster. | the genetic bases of sexual isolation between drosophila melanogaster and d. simulans have been mainly studied in females, and there is little information about the role of the males in interspecific mating discrimination. using d. simulans synthetic lines with compound chromosomes from a population of the seychelles islands (high frequency of interspecific mating) and a multimarker strain (low frequency), we show that d. simulans males play an important role in discriminating d. melanogaster fe ... | 2003 | 12939619 |
| sex-dependent gene expression and evolution of the drosophila transcriptome. | comparison of the gene-expression profiles between adults of drosophila melanogaster and drosophila simulans has uncovered the evolution of genes that exhibit sex-dependent regulation. approximately half the genes showed differences in expression between the species, and among these, approximately 83% involved a gain, loss, increase, decrease, or reversal of sex-biased expression. most of the interspecific differences in messenger rna abundance affect male-biased genes. genes that differ in expr ... | 2003 | 12805547 |
| patterns of dna sequence polymorphism at sod vicinities in drosophila melanogaster: unraveling the footprint of a recent selective sweep. | we survey dna sequence polymorphisms at the sod locus and four neighboring regions of drosophila melanogaster, spanning 55,513 base pairs (bp), in 15 strains from a natural population, plus one reference laboratory strain and one strain of drosophila simulans. our objective is to characterize a proposed selective sweep that occurred at a locus close to sod in d. melanogaster and to characterize the strength of the selection event, its time, and the size of the hitchhiked region. two regions, 181 ... | 2003 | 12578968 |
| evolution of gene expression in the drosophila melanogaster subgroup. | little is known about broad patterns of variation and evolution of gene expression during any developmental process. here we investigate variation in genome-wide gene expression among drosophila simulans, drosophila yakuba and four strains of drosophila melanogaster during a major developmental transition--the start of metamorphosis. differences in gene activity between these lineages follow a phylogenetic pattern, and 27% of all of the genes in these genomes differ in their developmental gene e ... | 2003 | 12548287 |
| allometric and nonallometric components of drosophila wing shape respond differently to developmental temperature. | phenotypic plasticity of wing size and shape of drosophila simulans was analyzed across the entire range of viable developmental temperatures with procrustes geometric morphometric method. in agreement with previous studies, size clearly decreases when temperature increases. wing shape variation was decomposed into its allometric (24%) and nonallometric (76%) components, and both were shown to involve landmarks located throughout the entire wing blade. the allometric component basically revealed ... | 2003 | 14761056 |
| the genetics of mating recognition between drosophila simulans and d. sechellia. | during courtship, visual and chemical signals are often exchanged between the sexes. the proper exchange of such signals ensures intraspecific recognition. we have examined the genetic basis of interspecific differences in male mating behaviour and pheromone concentration between drosophila simulans and d. sechellia by using drosophila simulans/d. sechellia introgression lines. our results show a majority of quantitative trait loci (qtls) explaining variation in both male mating behaviour and ph ... | 2003 | 14768896 |
| genetic dissection of hybrid incompatibilities between drosophila simulans and d. mauritiana. ii. mapping hybrid male sterility loci on the third chromosome. | hybrid male sterility (hms) is a rapidly evolving mechanism of reproductive isolation in drosophila. here we report a genetic analysis of hms in third-chromosome segments of drosophila mauritiana that were introgressed into a d. simulans background. qualitative genetic mapping was used to localize 10 loci on 3r and a quantitative trait locus (qtl) procedure (multiple-interval mapping) was used to identify 19 loci on the entire chromosome. these genetic incompatibilities often show dominance and ... | 2003 | 12930748 |
| genetic dissection of hybrid incompatibilities between drosophila simulans and d. mauritiana. i. differential accumulation of hybrid male sterility effects on the x and autosomes. | the genetic basis of hybrid incompatibility in crosses between drosophila mauritiana and d. simulans was investigated to gain insight into the evolutionary mechanisms of speciation. in this study, segments of the d. mauritiana third chromosome were introgressed into a d. simulans genetic background and tested as homozygotes for viability, male fertility, and female fertility. the entire third chromosome was covered with partially overlapping segments. many segments were male sterile, while none ... | 2003 | 12930747 |
| sperm chromatin remodelling and wolbachia-induced cytoplasmic incompatibility in drosophila. | wolbachia pipientis is an obligate bacterial endosymbiont, which has successfully invaded approximately 20% of all insect species by manipulating their normal developmental patterns. wolbachia-induced phenotypes include parthenogenesis, male killing, and, most notably, cytoplasmic incompatibility. in the future these phenotypes might be useful in controlling or modifying insect populations but this will depend on our understanding of the basic molecular processes underlying insect fertilization ... | 2003 | 12897857 |
| influence of two wolbachia strains on population structure of east african drosophila simulans. | drosophila simulans is hypothesized to have originated in continental east africa or madagascar. in this study, we investigated evolutionary forces operating on mitochondrial dna (mtdna) in populations of d. simulans from zimbabwe, malawi, tanzania, and kenya. variation in mtdna may be affected by positive selection, background selection, demographic history, and/or any maternally inherited factor such as the bacterial symbiont wolbachia. in east africa, the wri and wma wolbachia strains associa ... | 2003 | 14704179 |
| characterization of non-cytoplasmic incompatibility inducing wolbachia in two continental african populations of drosophila simulans. | wolbachia is an endocellular bacterium infecting arthropods and nematodes. in arthropods, it invades host populations through various mechanisms, affecting host reproduction, the most common of which being cytoplasmic incompatibility (ci). ci is an embryonic mortality occurring when infected males mate with uninfected females or females infected by a different wolbachia strain. this phenomenon is observed in drosophila simulans, an intensively studied wolbachia host, harbouring at least five dis ... | 2003 | 12522425 |
| superinfection of laodelphax striatellus with wolbachia from drosophila simulans. | wolbachia are maternally inherited, intracellular alpha-proteobacteria that infect a wide range of arthropods. they manipulate the reproduction of hosts to facilitate their spread into host populations, through ways such as cytoplasmic incompatibility (ci), parthenogenesis, feminization and male killing. the influence of wolbachia infection on host populations has attracted considerable interest in their possible role in speciation and as a potential agent of biological control. in this study, w ... | 2003 | 12522428 |
| wolbachia distribution and cytoplasmic incompatibility during sperm development: the cyst as the basic cellular unit of ci expression. | the growth and distribution of the intracellular microbe wolbachia pipientis during spermatogenesis in several different host/symbiont genetic combinations in drosophila melanogaster and drosophila simulans is described. considerable intra- and inter-strain variation in wolbachia density and tissue distribution was observed. wolbachia were found inside spermatocytes and spermatids or within the somatic cyst cells surrounding the germ cells. some strains displayed both tissue distributions. high ... | 2003 | 12559491 |
| genetic dissection of hybrid incompatibilities between drosophila simulans and d. mauritiana. iii. heterogeneous accumulation of hybrid incompatibilities, degree of dominance, and implications for haldane's rule. | the genetic basis of haldane's rule was investigated through estimating the accumulation of hybrid incompatibilities between drosophila simulans and d. mauritiana by means of introgression. the accumulation of hybrid male sterility (hms) is at least 10 times greater than that of hybrid female sterility (hfs) or hybrid lethality (hl). the degree of dominance for hms and hl in a pure d. simulans background is estimated as 0.23-0.29 and 0.33-0.39, respectively; that for hl in an f1 background is un ... | 2003 | 14686533 |
| mitochondrial genotype affects fitness in drosophila simulans. | drosophila simulans is known to harbor three distinct mitochondrial dna (mtdna) haplotype groups (sii, -ii, and -iii) with nearly 3.0% interhaplotypic divergence but <0.06% intrahaplotypic diversity. with the large amount of genetic variation in this system, the potential power to detect intraspecific fitness differences in fly lines that carry distinct haplotypes is great. we test three life-history traits on fly lines with known sequence differences in the mtdna genome after controlling the nu ... | 2003 | 12750331 |
| variability on the dot chromosome in the drosophila simulans clade. | a recent study suggested that recent nuclear gene introgression between drosophila simulans and d. mauritiana may have obscured efforts to estimate the phylogeny of the species of the d. simulans clade, which includes these two species and d. sechellia. here, we report sequence variation of an intron of the eyeless gene in this species group. this gene should introgress freely between these species because it is not linked to any known barriers to gene exchange. we have also reevaluated levels o ... | 2003 | 12733664 |
| the evolution of autosomal suppressors of sex-ratio drive in drosophila simulans. | sex-ratio drive, which results in males siring female-biased progeny, has been reported in several drosophila species, including d. simulans. it is caused by x-linked drivers that prevent the production of y-bearing sperm. in natural populations of d. simulans, the drivers are usually cryptic, because their spread has elicited the evolution of drive suppressors. we investigated autosomal suppression in flies from madagascar, réunion and kenya. autosomal suppressors were found in all three places ... | 2003 | 12656572 |
| worldwide distribution of transposable element copy number in natural populations of drosophila simulans. | transposable elements (tes), which promote various kinds of mutations, constitute a large fraction of the genome. how they invade natural populations and species is therefore of fundamental importance for understanding the dynamics of genetic diversity and genome composition. on the basis of 85 samples of natural populations of drosophila simulans, we report the distributions of the genome insertion site numbers of nine tes that were chosen because they have a low average number of sites. most p ... | 2003 | 12643577 |
| a mariner-like element with a 5' lesion in drosophila simulans. | the unstable white-s2 (ws2) allele of the white gene occurred spontaneously in the s2 strain of drosophila simulans. this mutation was caused by insertion of the submariner element, a mariner-like element with an abnormal tandem duplication of the 5' inverted terminal repeat (itr). although it has an incomplete itr, submariner excises efficiently. the rate of somatic reversion, estimated by the number of eye-color mosaic flies, was 79.9%, and the reversion frequency in the germline was 0.6%. the ... | 2003 | 14686602 |
| [random amplified polymorphic dna (rapd) analysis of drosophila simulans in the mainland of china]. | the widespread distribution of drosophila simulans in the mainland of china was found recently. random amplified polymorphic dna (rapd) was used to analyzed dna polymorphisms of 38 drosophila simulans populations collected from the mainland of china. the origins of d. simulans in china were also discussed. using 40 arbitary primers (10 bp), we made pcr amplifications under the optimized reaction conditions for rapd that had been established in our laboratory. our molecular phylogenetic tree cons ... | 2003 | 14579539 |
| large-scale adaptive hitchhiking upon high recombination in drosophila simulans. | natural selection is expected to leave a characteristic footprint on neighboring nucleotide variation through the effects of genetic linkage. the size of the region affected is proportional to the strength of selection and greatly reduced with the recombinational distance from the selected site. thus, the genomic footprint of selection is generally believed to be restricted to a small dna stretch in normal and highly recombining regions. here, we study the effect of selection on linked polymorph ... | 2003 | 14573496 |
| natural selection drives drosophila immune system evolution. | evidence from disparate sources suggests that natural selection may often play a role in the evolution of host immune system proteins. however, there have been few attempts to make general population genetic inferences on the basis of analysis of several immune-system-related genes from a single species. here we present dna polymorphism and divergence data from 34 genes thought to function in the innate immune system of drosophila simulans and compare these data to those from 28 nonimmunity gene ... | 2003 | 12930753 |
| genetic studies on premating isolation in drosophila simulans. ii. a d. simulans line highly crossable to males of d. yakuba and d. teissieri. | females of the s1 line of drosophila simulans, an isofemale line from a natural population at mishima, japan, were found to show high crossability to males of d. yakuba and d. teissieri. with d. yakuba males, 24.0-58.5% of the s1 females were inseminated, while the rate was only 0.0-6.3% for the control lines. the high crossability was ascribed to the genes on the x and third chromosomes. with d. teissieri males, 38.0-51.5% of the s1 females were inseminated, while the rate was only 0.0-6.2% for ... | 2003 | 12773816 |
| association of misexpression with sterility in hybrids of drosophila simulansand d. mauritiana. | recent studies have identified genes associated with hybrid sterility and other hybrid dysfunctions, but the consequences of introgressions of these "speciation genes" are often poorly understood. previously, we identified a panel of genes that are underexpressed in sterile male hybrids of drosophila simulans and d. mauritiana relative to pure species. here, we build on this reverse-genetics approach to demonstrate that the underexpression of at least five of these genes in hybrids is associated ... | 2004 | 15486701 |
| identification of a locus under complex positive selection in drosophila simulans by haplotype mapping and composite-likelihood estimation. | the recent action of positive selection is expected to influence patterns of intraspecific dna sequence variation in chromosomal regions linked to the selected locus. these effects include decreased polymorphism, increased linkage disequilibrium, and an increased frequency of derived variants. these effects are all expected to dissipate with distance from the selected locus due to recombination. therefore, in regions of high recombination, it should be possible to localize a target of selection ... | 2004 | 15454542 |
| wolbachia and cytoplasmic incompatibility in mosquitoes. | wolbachia are maternally inherited bacteria that induce cytoplasmic incompatibility in mosquitoes, and are able to use these patterns of sterility to spread themselves through populations. for this reason they have been proposed as a gene drive system for mosquito genetic replacement, as well as for the reduction of population size or for modulating population age structure in order to reduce disease transmission. here, recent progress in the study of mosquito wolbachia is reviewed. we now have ... | 2004 | 15242714 |
| wolbachia transfer from rhagoletis cerasi to drosophila simulans: investigating the outcomes of host-symbiont coevolution. | wolbachia is an endosymbiont of diverse arthropod lineages that can induce various alterations of host reproduction for its own benefice. cytoplasmic incompatibility (ci) is the most common phenomenon, which results in embryonic lethality when males that bear wolbachia are mated with females that do not. in the cherry fruit fly, rhagoletis cerasi, wolbachia seems to be responsible for previously reported patterns of incompatibility between populations. here we report on the artificial transfer o ... | 2004 | 14711652 |
| molecular evolution of x-linked accessory gland proteins in drosophila pseudoobscura. | in drosophila melanogaster and drosophila simulans, positive darwinian selection drives high rates of evolution of male reproductive genes, and accessory gland proteins (acps) in particular. here, we tested whether 13 x-linked male-specific genes, 4 acps and 9 non-acps, are under selective forces in the drosophila pseudoobscura species group, much as those in the d. melanogaster group. we observed a statistically significant correlation in relative rates of nonsynonymous evolution between the tw ... | 2004 | 15073226 |
| drosophila melanogaster, drosophila simulans: so similar yet so different. | during the last two decades, the two cosmopolitan species drosophila melanogaster and drosophila simulans have been compared with regard to numerous characteristics, ranging from their geographic distribution and ecology to their dna polymorphism. various traits have been compared, including morphology, physiology, sexual behavior, allozymes and other proteins, chromosomal inversions, mitochondrial and nuclear dna, transposable elements, wolbachia etc. such comparisons reveal similarities and di ... | 2004 | 15088643 |
| conservation and divergence of the genetic structure of larval foraging behaviour in two species of the drosophila simulans clade. | larvae of the sibling species drosophila simulans and d. mauritiana have rates of locomotor and feeding activity that are closely similar. comparisons of the trait means for intra- and interspecific hybrids show that significant epistatic interactions affect both characters when the genomes of the two species are combined. the phenotypic variances of progenies obtained by backcrossing the interspecific hybrids to their respective parent species show that appreciable genetic turnover affecting fo ... | 2004 | 14508499 |
| sequential evolution of a symbiont inferred from the host: wolbachia and drosophila simulans. | this study aims to unravel the biogeography of a model symbiont/host system by exploiting the prediction that a symbiont will leave a signature of infection on the host. specifically, a global sample of 1,442 drosophila simulans from 33 countries and 64 sampling localities was employed to infer the phylogeography of the maternally inherited alpha-proteobacteria wolbachia. phylogenetic analyses, from three symbiont genes and 24 mtdna genomes (excluding the a + t-rich region), showed that each of ... | 2004 | 14660690 |
| bacteriophage flux in endosymbionts (wolbachia): infection frequency, lateral transfer, and recombination rates. | the highly specialized genomes of bacterial endosymbionts typically lack one of the major contributors of genomic flux in the free-living microbial world-bacteriophages. this study yields three results that show bacteriophages have, to the contrary, been influential in the genome evolution of the most prevalent bacterial endosymbiont of invertebrates, wolbachia. first, we show that bacteriophage wo is more widespread in wolbachia than previously recognized, occurring in at least 89% (35/39) of t ... | 2004 | 15254259 |
| linking phylogenetics with population genetics to reconstruct the geographic origin of a species. | reconstructing ancestral geographic origins is critical for understanding the long-term evolution of a species. bayesian methods have been proposed to test biogeographic hypotheses while accommodating uncertainty in phylogenetic reconstruction. however, the problem that certain taxa may have a disproportionate influence on conclusions has not been addressed. here, we infer the geographic origin of drosophila simulans using 2,014 bp of the period locus from 63 lines collected from 18 countries. w ... | 2004 | 15288072 |
| incipient evolution of wolbachia compatibility types. | cytoplasmic incompatibility (ci) is induced in arthropods by the maternally inherited bacterium wolbachia. when infected males mate with uninfected females or with females bearing a different wolbachia variant, paternal chromosomes behave abnormally and embryos die. this pattern can be interpreted as resulting from two bacterial effects: one (usually termed mod, for modification) would affect sperm and induce embryo death, unless wolbachia is also present in the egg, which implies the existence ... | 2004 | 15521450 |
| strain-specific quantification of wolbachia density in aedes albopictus and effects of larval rearing conditions. | the density of the endosymbiont wolbachia can influence the expression of the crossing sterilities known as cytoplasmic incompatibility (ci), and also its rate of maternal transmission. aedes albopictus mosquitoes contain a superinfection with the wolbachia strains walba and walbb. a strain-specific real-time quantitative pcr assay was developed and used to quantify relative wolbachia strain densities within individual mosquitoes. the walbb strain was consistently found to be at higher density t ... | 2004 | 15157232 |
| signature of selective sweep associated with the evolution of sex-ratio drive in drosophila simulans. | in several drosophila species, the xy mendelian ratio is disturbed by x-linked segregation distorters (sex-ratio drive). we used a collection of recombinants between a nondistorting chromosome and a distorting x chromosome originating from the seychelles to map a candidate sex-ratio region in drosophila simulans using molecular biallelic markers. our data were compatible with the presence of a sex-ratio locus in the 7f cytological region. using sequence polymorphism at the nrg locus, we showed t ... | 2004 | 15082554 |
| ecological and genetic interactions in drosophila-parasitoids communities: a case study with d. melanogaster, d. simulans and their common leptopilina parasitoids in south-eastern france. | drosophila species are attacked by a number of parasitoid wasps, which constitute an important factor of population regulation. since drosophila melanogaster and drosophila simulans share common parasitoid species, their ecology and evolution can hardly be understood without considering parasitoids. after a short review of data available on drosophila-parasitoid interactions involving d. melanogaster and d. simulans as hosts, we report field and laboratory experiments investigating the ecologica ... | 2004 | 15088657 |
| molecular analysis of circadian clocks in drosophila simulans. | the drosophila simulans per gene is polymorphic for the length of a repeat that encodes a series of thr-gly pairs. we have examined the circadian behaviour of flies derived from isofemale lines that carry the major variants, and find some significant differences in the way that the clock responds to temperature challenge, that might relate to the observed frequencies of these alleles in nature. we also observe that circadian thermal behaviour is also predictably influenced by subtle differences ... | 2004 | 15088659 |
| a mutation in drosophila simulans that lengthens the circadian period of locomotor activity. | the length of the thr-gly repeat within the period gene of drosophilids, coevolves with its immediate flanking region to maintain the temperature compensation of the fly circadian clock. in drosophila simulans, balancing selection appears to maintain a polymorphism in this region, with three repeat lengths carrying 23, 24 or 25 thr-gly pairs, each in complete linkage disequilibrium with a distinctive flanking region amino acid moiety. we wondered whether separating a specific length repeat from ... | 2004 | 15088660 |
| differential fitness of mitochondrial dna in perturbation cage studies correlates with global abundance and population history in drosophila simulans. | mitochondria are often referred to as the powerhouse of the cell. however, research linking intraspecific differences in organismal fitness with genotypic mitochondrial dna (mtdna) variation has been hampered by the lack of variation in experimentally tractable species. this study examines whether fly lines harbouring three distinct drosophila simulans mtdna types (sii, -ii and -iii) exhibit differential fitness in laboratory perturbation cages. comparison of the pre-perturbation and post-pertur ... | 2004 | 15306370 |
| [structural organization and distribution of symbiotic bacteria wolbachia in early embryos and ovaries of drosophila melanogaster and d. simulans]. | electron microscopic and morphometric analyses of wolbachia distribution in early embryos of drosophila flies have demonstrated that the number of bacteria in the embryo remains constant from fertilization to blastoderm, and that afterwards the symbionts could be observed only in the polar cells. each bacterium has a three-layer envelope, makes contacts with microtubules and moves through the cytoplasm following the actively dividing nuclei. it has been found for the first time that wolbachia co ... | 2004 | 15214166 |
| a reanalysis of protein polymorphism in drosophila melanogaster, d. simulans, d. sechellia and d. mauritiana: effects of population size and selection. | comparison of synonymous and nonsynonymous variation/substitution within and between species at individual genes has become a widely used general approach to detect the effect of selection versus drift. the sibling species group comprised of two cosmopolitan (drosophila melanogaster and drosophila simulans) and two island (drosophila mauritiana and drosophila sechellia) species has become a model system for such studies. in the present study we reanalyzed the pattern of protein variation in thes ... | 2004 | 15088651 |