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[role of propionic acid, yeasts and ethyl alcohol in regulating the activity of h-factor in drosophila simulans].effects of yeast, propionic acid and ethanol on the activity of h-factor, which sharply increases the frequency of somatic recombination in x-chromosomes of dorsal prothoracal disc cells in drosophila simulans are studied. the frequency of yellow and singed mosaic spots in heterozygous yw ++/++sn1vhd. melanogaster females, inherited h-factor from the father (the stock sn1v) is estimated. the results of the varience analysis have shown that yeast and propionic acid regulate the activity of h-fact ...1977355052
transmission of the hereditary s character in drosophila simulans: effects of aging and temperature treatments.the expression of the s character of drosophila simulans associated to hereditary reovirus dsv is affected by the rearing temperature. the transmission of the s character and the consequences of the length of high temperature (28 degrees c) treatments on that transmission were investigated. larvae treated at 28 degrees c from eclosion to imaginal emergence produce few s individuals in the offspring. the offspring of larvae treated between the 144th hr of development (middle of the pupal stage) a ...19921607670
cytoplasmic incompatibility in drosophila simulans: dynamics and parameter estimates from natural populations.in drosophila simulans, cytoplasmically transmitted wolbachia microbes cause reduced egg hatch when infected males mate with uninfected females. a wolbachia infection and an associated mtdna variant have spread northward through california since 1986. pcr assays show that wolbachia infection is prevalent throughout the continental us and central and south america, but some lines from florida and ecuador that are pcr-positive for wolbachia do not cause incompatibility. we estimate from natural po ...19957498773
cloning and characterization of an ftsz homologue from a bacterial symbiont of drosophila melanogaster.a 1194 bp open reading frame that codes for a 398 amino acid peptide was cloned from a lambda gt11 library of drosophila melanogaster genomic dna. the predicted peptide sequence is very similar to three previously characterized protein sequences that are encoded by the ftsz genes in escherichia coli, bacillus subtilis and rhizobium meliloti. the ftsz protein has a major role in the initiation of cell division in prokaryotic cells. using a tetracycline treatment that eradicates bacterial parasite ...19937689140
replacement of the natural wolbachia symbiont of drosophila simulans with a mosquito counterpart.inherited rickettsial symbionts of the genus wolbachia occur commonly in arthropods and have been implicated in the expression of parthenogenesis, feminization and cytoplasmic incompatibility wolbachia from the asian tiger mosquito, aedes albopictus, to replace the natural infection of drosophila simulans by means of embryonic microinjection techniques. the transferred wolbachia infection behaves like a natural drosophila infection with regard to its inheritance, cytoskeleton interactions and ab ...19947906391
evolutionary inferences from dna variation at the 6-phosphogluconate dehydrogenase locus in natural populations of drosophila: selection and geographic differentiation.several allozyme-coding genes in drosophila melanogaster show patterns suggesting that polymorphisms at these loci are targets of balancing selection. an important question is whether these genes have similar distributions of underlying dna sequence variation which would indicate similar evolutionary processes occurring in this class of loci. one such locus, 6-phosphogluconate dehydrogenase (pgd), has previously been shown to exhibit clinal variation for fast/slow electromorph variation in the u ...19948138153
variability within the seychelles cytoplasmic incompatibility system in drosophila simulans.in drosophila simulans, we described a cytoplasmic incompatibility (ci) system (seychelles) restricted to insular populations that harbor the mitochondrial type sii. since then, these populations have been shown to be heterogeneous, some being infected by one wolbachia genetic variant only (wha), while others are infected simultaneously by wha and by another variant (wno) always found in association with wha. we have experimentally obtained two d. simulans strains only infected by the wno varian ...19958582608
wolbachia superinfections and the expression of cytoplasmic incompatibility.strains of drosophila simulans from riverside, california (dsr) and hawaii (dsh) harbour distinct strains of the cytoplasmic incompatibility microorganism wolbachia, resulting in the expression of bidirectional incompatibility when crossed. d. simulans lines carrying both of these (superinfected) wolbachia strains were generated by the transfer of infected dsh cytoplasm into dsr embryos by microinjection. the superinfected flies were unidirectionally incompatible with both dsr and dsh individual ...19958587875
a molecular taxonomy for cricket paralysis virus including two new isolates from australian populations of drosophila (diptera: drosophilidae).two new isolates of cricket paralysis virus, tar and sim, are described that were originally isolated from laboratory colonies of drosophila melanogaster and drosophila simulans respectively. using a combination of biological, serological and molecular characters it was possible to distinguish the sim isolate from all other isolates and it is thus described as a new strain; crpvsim. the tar isolate however, was indistinguishable from the crpv reference isolate crpvvic/gm/d2(2)/gm/d2(2) (teleogry ...19968856030
overcoming cytoplasmic incompatibility in drosophila.the endocellular microbe wolbachia pipientis infects a wide variety of invertebrate species, in which its presence is closely linked to a form of reproductive failure termed cytoplasmic incompatibility (ci). ci renders infected males unable to father offspring when mated to uninfected females. because ci can dramatically affect fitness in natural populations, mechanisms that abate ci can have equally large impacts on fitness. we have discovered that repeated copulation by wolbachia-infected male ...19989523438
infection of the gonads of the simes strain of drosophila simulans by the hereditary reovirus dsv.the s character of drosophila simulans simes-st strain undergoes a non-mendelian transmission. it has been postulated that a virus, drosophila s virus (dsv), could be the causative agent. electron microscopy analysis of gonads of flies showing a strong s phenotype revealed the presence of virus in or near the germ cells. the s character transmission rate is greater in females than that in males. similarly, the level of infection by dsv is higher in ovaries than that in testes. flies treated at a ...19979281403
reduced variation in drosophila simulans mitochondrial dna.we investigated the evolutionary dynamics of infection of a drosophila simulans population by a maternally inherited insect bacterial parasite, wolbachia, by analyzing nucleotide variability in three regions of the mitochondrial genome in four infected and 35 uninfected lines. mitochondrial variability is significantly reduced compared to a noncoding region of a nuclear-encoded gene in both uninfected and pooled samples of flies, indicating a sweep of genetic variation. the selective sweep of mi ...19968978041
horizontal transfer of wolbachia between phylogenetically distant insect species by a naturally occurring mechanism.wolbachia is a genus of alpha-proteobacteria found in obligate intracellular association with a wide variety of arthropods, including an estimated 10-20% of all insect species [1]. wolbachia represents one of a number of recently identified 'reproductive parasites' [2] which manipulate the reproduction of their hosts in ways that enhance their own transmission [3] [4] [5] [6] [7] [8] [9]. the influence of wolbachia infection on the dynamics of host populations has focused considerable interest o ...199910209097
interspecific and intraspecific horizontal transfer of wolbachia in drosophila.cytoplasmic incompatibility (ci) in drosophila simulans is related to infection of the germ line by a rickettsial endosymbiont (genus wolbachia). wolbachia were transferred by microinjection of egg cytoplasm into uninfected eggs of both d. simulans and d. melanogaster to generate infected populations. transinfected strains of d. melanogaster with lower densities of wolbachia than the naturally infected d. simulans strain did not express high levels of ci. however, transinfected d. melanogaster e ...19938511587
centromeres from telomeres? the centromeric region of the y chromosome of drosophila melanogaster contains a tandem array of telomeric het-a- and tart-related sequences.cytological and cytogenetic studies have previously defined the region needed for centromeric function in the y chromosome of drosophila melanogaster. we have identified a yac clone that originated from this region. molecular analysis of the yac and genomic dnas has allowed the description of a satellite dna made of telomeric het-a- and tart-derived sequences and the construction of a long-range physical map of the heterochromatic region h18. sequences within the yac clone are conserved in the c ...199910454639
a combined classical genetic and high resolution two-dimensional electrophoretic approach to the assessment of the number of genes affecting hybrid male sterility in drosophila simulans and drosophila sechellia.we have attempted to estimate the number of genes involved in postzygotic reproductive isolation between two closely related species, drosophila simulans and drosophila sechellia, by a novel approach that involves the use of high resolution two-dimensional gel electrophoresis (2de) to examine testis proteins in parents, hybrids and fertile and sterile backcross progenies. the important results that have emerged from this study are as follows: (1) about 8% of about 1000 proteins examined showed d ...19938224814
properties of drosophila simulans strains experimentally infected by different clones of the bacterium wolbachia.maternally inherited bacteria of the genus wolbachia are responsible for reproductive incompatibilities between strains of drosophila simulans. such incompatibilities are known in several types of crosses, including both directions of crossing between two types of infected strains, 'r' and 's'. to determine whether the bidirectional incompatibility between r and s flies is due only to differences between their bacteria, flies from an uninfected strain have been experimentally infected with bacte ...19948200813
cytoplasmic incompatibility in australian populations of drosophila melanogaster.in drosophila melanogaster, weak incompatibility in crosses between infected and uninfected strains is associated with a wolbachia microorganism. crosses between infected males and uninfected females show a reduction (15-30%) in egg hatch. progeny tests indicated that the infection is widespread in australian d. melanogaster populations and that populations are polymorphic for the presence of the infection. the infection status of 266 lines from 12 populations along the eastern coast of australi ...19948005448
a prokaryotic dnaa sequence in drosophila melanogaster: wolbachia infection and cytoplasmic incompatibility among laboratory strains.using oligonucleotide primers derived from the aligned polypeptide sequences of several prokaryotic dnaa genes, we amplified from drosophila melanogaster dna a 557 bp fragment containing a single open reading frame. the predicted peptide sequence shows a significant similarity to previously characterized protein sequences that are encoded by the dnaa genes of several prokaryotes. the dnaa sequences are also detectable by pcr in dna from drosophila simulans and nasonia vitripennis flies which are ...19947894745
mating propensity of indian drosophila melanogaster populations with d. simulans: a nonadaptive latitudinal cline.crosses were investigated between a single strain of drosophila simulans and 28 natural indian populations of d. melanogaster. in each case, a mass culture and 10 isofemale lines of d. melanogaster were studied. crosses were much easier between d. melanogaster females and d. simulans males than in the reciprocal case. also, hybrid offspring were easier to obtain by using d. melanogaster flies (either males or females) from isofemale lines than from mass cultures. finally, the crossability, estim ...19957759292
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 ...200011122472
evidence for a wolbachia symbiont in drosophila melanogaster.the bacterial cell division gene, ftsz, was used as a specific probe to show the presence of a symbiotic bacterium in two wild type strains of drosophila melanogaster. under stringent hybridization conditions we have shown that the bacterium is transferred to the progeny of these strains from infected mothers and can be eradicated by treatment with the antibiotic tetracycline. we have characterized this bacterium, by amplifying and sequencing its 16s rrna gene, as being a member of the genus wol ...19937691685
genetic variability at the esterase-6 locus in natural populations of drosophila simulans in relation to environmental heterogeneity.the allozymic variation at at the esterase-6 locus examined in fourteen samples of natural populations of drosophila simulans collected in two different localities. the samples were collected from different species of fruits in the two localities and from banana baits located some meters apart from the fruits. the analysis was done by sequential electrophoresis, using varied gel concentrations and buffers. by this technique, we detected 27 alleles at the esterase-6 locus, where only five alleles ...19817327390
estimation of genetic variability in natural populations of drosophila simulans by two-dimensional and starch gel electrophoresis.genic variation in natural populations of drosophila simulans was surveyed using allozymic and two-dimensional electrophoretic techniques. consistent with some previous reports, allozymic heterozygosity appeared lower than in the sibling species d. melanogaster (0.07 vs. 0.16). no variation was detected by two-dimensional electrophoresis of 19 lines scored for 70 abundant proteins. this is consistent with reported reductions in estimates of genic heterozygosity by two-dimensional electrophoresis ...19827095420
factors affecting the distribution of cytoplasmic incompatibility in drosophila simulans.in drosophila simulans a wolbachia-like microorganism is responsible for reduced egg-hatch when infected males mate with uninfected females. both incompatibility types have previously been found in north america, europe and africa. some california populations have remained polymorphic for over two years, and the infection is apparently spreading in central california. egg hatch proportions for wild-caught females from polymorphic populations show that the incompatibility system acts in nature, b ...19902076821
the effect of heteroplasmy on cytoplasmic incompatibility in transplasmic lines of drosophila simulans showing a complete replacement of the mitochondrial dna.unidirectional cytoplasmic incompatibility has been observed in crosses between different strains of drosophila simulans when the males, but not the females, involved in the crosses are infected with intracellular rickettsia-like microorganisms. in contrast to what is known about this system an unexpected partial incompatibility has been observed between two infected strains. transplasmic lines have been constructed in the laboratory to investigate this phenomenon. the injection of a foreign inf ...19912010316
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 ...200211823204
molecular identification of wolbachia, the agent of cytoplasmic incompatibility in drosophila simulans, and variability in relation with host mitochondrial types.sequences of a segment of the 16s ribosomal dna of wolbachia, a rickettsia-like microorganism responsible for cytoplasmic incompatibility in drosophila simulans, have been obtained after polymerase chain reaction (pcr) amplification. their comparison with other eubacterial sequences allows us to assign these endosymbionts to the alpha subdivision of purple bacteria. four related sequences have been obtained for microorganisms carried by eight isofemale lines representative of the three mitochond ...19921350096
wolbachia-induced delay of paternal chromatin condensation does not prevent maternal chromosomes from entering anaphase in incompatible crosses of drosophila simulans.the behavior of parental chromosomes during the first mitosis of drosophila simulans zygotes obtained from unidirectional incompatible crosses is described and it is demonstrated that the condensation of parental chromatin complements was asynchronous. the timing of paternal chromatin condensation appeared to be delayed in these embryos, so that condensed maternal chromosomes and entangled prophase-like paternal fibers congressed in the equatorial plane of the first metaphase spindle. at anaphas ...19979044057
cytological analysis of fertilization and early embryonic development in incompatible crosses of drosophila simulans.cytoplasmic incompatibility (ci) is a unique form of male sterility found in numerous insect species that harbor a bacterial endosymbiont wolbachia. ci is characterized by severe reduction in the progeny produced when infected males are crossed to uninfected females. the reduction in progeny correlates with developmental defects that arise during and immediately following fertilization, suggesting that sperm function is disrupted. to investigate the nature of the cellular defects associated with ...19968817452
the reproductive incompatibility system in drosophila simulans: dapi-staining analysis of the wolbachia symbionts in sperm cysts.any hitherto available technique used to detect the presence of wolbachia, a rickettsia-like endosymbiont of drosophila simulans, i.e., crossing with tester strains, electron microscope observations, dapi-staining of embryo, or amplification of specific sequences by pcr are notably time-consuming techniques. staining sperm cysts with the fluorochrome dapi is here shown to be a fast and reliable technique to detect the symbiont and evaluate the level of infection of individual males. wolbachia ce ...19937689622
bidirectional incompatibility between conspecific populations of drosophila simulans.cytoplasmic incompatibility (ci) describes the phenomenon whereby eggs fertilized by sperm from insects infected with a rickettsial endosymbiont fail to hatch. unidirectional ci between conspecific populations of insects is a well documented phenomenon. bidirectional ci has, however, only been described in mosquito populations, and recently between closely related species of parasitic wasps, where it is of interest as both an unusual form of reproductive isolation and as a potential means of ins ...19902234083
is there selection on rflp differences in mitochondrial dna?experimental populations of drosophila simulans were established for the purpose of detecting the presence or absence of selection on a restriction fragment length polymorphism in mitochondrial dna (mtdna). it was then discovered that the founding strains differed with respect to the rickettsia-mediated incompatibility system in this species, which is maternally transmitted together with the mtdna differences. a population model was constructed using the known fitness effects of the incompatibil ...19901974225
geographic distribution and inheritance of three cytoplasmic incompatibility types in drosophila simulans.wolbachia-like microorganisms have been implicated in unidirectional cytoplasmic incompatibility between strains of drosophila simulans. reduced egg eclosion occurs when females from uninfected strains (type w) are crossed with males from infected strains (type r). here we characterize a third incompatibility type (type s) which is also correlated with the presence of wolbachia-like microorganisms. despite the fact that the symbionts cannot be morphologically distinguished, we observed complete ...19911743484
a drosophila simulans mutant strain sensitive to benzo[a]pyrene and 2-acetylaminofluorene.we have identified a drosophila simulans mutant, 364 yu, that is sensitive to the toxic effects of the procarcinogens b(a)p and 2-aaf. heterozygotes obtained by crossing it to the wild resistant turku strain (female 364 yu x male turku) were more sensitive than heterozygotes obtained from the reciprocal cross (female turku x male 364 yu) to both the toxic and the mutagenic effects of b(a)p in drosophila tests that measured lethality and the induction of somatic mosaicism, respectively. the non-c ...19921378181
evolution of single and double wolbachia symbioses during speciation in the drosophila simulans complex.maternally inherited bacteria of the genus wolbachia are responsible for the early death of embryos in crosses between uninfected females and infected males in several insect species. this phenomenon, known as cytoplasmic incompatibility, also occurs between strains infected by different symbionts in some species, including drosophila simulans. wolbachia was found in two species closely related to d. simulans, drosophila mauritiana, and drosophila sechellia, and shown to cause incompatibility in ...19957604001
host-plant specialization in the drosophila melanogaster species complex: a physiological, behavioral, and genetical analysis.drosophila sechellia, endemic to the seychelles, breeds in a single resource, morinda citrifolia, whereas its close sympatric relative, drosophila simulans, is a cosmopolitan generalist breeding in a great variety of resources. the effects of morinda on various fitness traits of these two species, their f1 hybrids, and reciprocal backcrosses were analyzed. morinda fruit is highly toxic to drosophila species, except d. sechellia. the toxicity is expressed in adults, embryos, and larvae. in embryo ...19911900368
chromosomal monomorphism in brazilian and argentine populations of drosophila simulans and drosophila repleta. 196414239802
cross-order transfer of wolbachia from muscidifurax uniraptor (hymenoptera: pteromalidae) to drosophila simulans (diptera: drosophilidae).bacteria of the genus wolbachia are widespread in arthropods and can induce different effects on the host such as cytoplasmic incompatibility (ci), thelytoky (t) or feminization (f). in some wolbachia-infected hosts, no effect (n) has been found. successful transfer of wolbachia by microinjection from one host to an uninfected one has been established with ci, f, n-wolbachia but not with t-wolbachia. in this paper a transfer experiment of t-wolbachia from the parasitoid muscidifurax uniraptor to ...199910098265
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 ...200010903373
genetic variation and differentiation at microsatellite loci in drosophila simulans. evidence for founder effects in new world populations.drosophila simulans isofemale lines from africa, south america, and two locations in north america were surveyed for variation at 16 microsatellite loci on the x, second, and third chromosomes, and 18 microsatellites, which are unmapped. d. simulans is thought to have colonized new world habitats only relatively recently (within the last few hundred years). consistent with a founder effect occurring as colonizers moved into these new world habitats, we find less microsatellite variability in nor ...19989755208
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 ...200414711652
naturally-occurring wolbachia infection in drosophila simulans that does not cause cytoplasmic incompatibility.microbes of the genus wolbachia are transmitted by their hosts via the maternal parent and are responsible for cytoplasmic incompatibility among insect populations. this phenomenon can result in wolbachia spreading through natural populations as previously demonstrated in drosophila simulans. here we describe another wolbachia infection in d. simulans that does not cause cytoplasmic incompatibility. this is a property of the wolbachia rather than the nuclear background. the infection occurs at a ...19968575931
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 ...200415082554
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 ...200011012722
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 ...200312897857
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 ...200312522425
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 ...200211805302
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 ...200415157232
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 ...200312522428
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 ...200415242714
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 ...200010790392
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 ...200314704179
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 ...200011108593
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 ...200011209779
the sinbad retrotransposon from the genome of the human blood fluke, schistosoma mansoni, and the distribution of related pao-like elements.of the major families of long terminal repeat (ltr) retrotransposons, the pao/bel family is probably the least well studied. it is becoming apparent that numerous ltr retrotransposons and other mobile genetic elements have colonized the genome of the human blood fluke, schistosoma mansoni.200515725362
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 ...200111361350
[structural organization and distribution of the symbiotic bacteria wolbachia during spermatogenesis of drosophila simulans].electron microscopy and morphometric analysis have shown that the symbiotic bacteria wolbachia occur the testis cells during spermatogenesis and are absent in mature spermatids. bacteria did not affect the structural organization of testis cells, which have a typical morphology during morphogenesis. bacteria were distributed along the meiotic spindle microtubules near the mitochondria. they increased in number in spermatids at the stage of elongation. endosymbionts aggregated at the spermatid di ...200515807436
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 ...200211804774
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 ...200211880639
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 ...200211920119
efficient procedure for purification of obligate intracellular wolbachia pipientis and representative amplification of its genome by multiple-displacement amplification.bacteria belonging to the genus wolbachia are obligatory microendocytobionts that infect a variety of arthropods and a majority of filarial nematode species, where they induce reproductive alterations or establish a mutualistic symbiosis. although two whole genome sequences of wolbachia pipientis, for strain wmel from drosophila melanogaster and strain wbm from brugia malayi, have been fully completed and six other genome sequencing projects are ongoing (http://www.genomesonline.org/index.cgi?wa ...200516269725
a stable triple wolbachia infection in drosophila with nearly additive incompatibility effects.drosophila simulans strains infected with three different wolbachia strains were generated by experimental injection of a third symbiont into a naturally double-infected strain. this transfer led to a substantial increase in total wolbachia density in the host strain. each of the three symbionts was stably transmitted in the presence of the other two. triple-infected males were incompatible with double-infected females. no evidence was obtained for interference between modification effects of th ...199910383683
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 ...200212389718
wolbachia infection suppresses both host defence and parasitoid counter-defence.endosymbiotic bacteria in the genus wolbachia have been linked to several types of reproductive parasitism, which enhance their own transmission, while their direct effects on the host vary from beneficial to neutral or detrimental. here, we report negative effects of infection on immunity-related traits of drosophila simulans and the parasitoid wasp leptopilina heterotoma. infected d. simulans showed a reduced ability to encapsulate parasitoid eggs, compared to a tetracycline-treated, bacterium ...200616618671
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 ...200111749711
interspecific transfer of wolbachia into the mosquito disease vector aedes albopictus.intracellular wolbachia bacteria are obligate, maternally inherited endosymbionts found frequently in insects and other invertebrates. the evolutionary success of wolbachia is due in part to an ability to manipulate reproduction. in mosquitoes and many other insects, wolbachia causes a form of sterility known as cytoplasmic incompatibility (ci). wolbachia-induced ci has attracted interest as a potential agent for affecting medically important disease vectors. however, application of the approach ...200616777718
a wolbachia-associated fitness benefit depends on genetic background in drosophila simulans.the alpha-proteobacteria wolbachia infect a number of insect species and influence host reproduction to favour the spread of infected females through a population. the fitness effect of this infection is important in understanding the spread and maintenance of wolbachia within and among host populations. however, a full elucidation of fitness effect requires careful control of host genetic background. here, i transferred a single clone of wolbachia (the wha strain) into three genetically distinc ...200616777731
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 ...200415073226
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 ...200211989683
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.200011006639
symbiotic bacteria in oocyte and ovarian cell mitochondria of the tick ixodes ricinus: biology and phylogenetic position.under natural conditions, eukaryote cells may contain bacteria. arthropods such as ticks, insects or mites are a group particularly favoured by the obligate intracellular bacteria. while arthropods are vectors for some of them, other bacteria inhabit invertebrate host cells having entered mutualistic interactions. such endosymbionts dwell usually in the host cell vacuoles or cytoplasm but have been also reported from tick oocyte mitochondria. the microorganisms contribute to mitochondria degrada ...200717226040
high divergence among drosophila simulans mitochondrial haplogroups arose in midst of long term purifying selection.we characterize the type of selection acting within and among mitochondrial lineages in five closely related drosophila species. we focus on d. simulans, where three genetically distinct mitochondrial haplogroups show high interhaplogroup divergence and low intrahaplogroup polymorphism. using maximum likelihood models we find that the branches leading to these three distinct mitochondrial groups show a significantly reduced rate of nonsynonymous relative to synonymous substitution. this interhap ...200515955513
a female-biased expressed elongase involved in long-chain hydrocarbon biosynthesis and courtship behavior in drosophila melanogaster.drosophila melanogaster produces sexually dimorphic cuticular pheromones that are a key component of the courtship behavior leading to copulation. these molecules are hydrocarbons, with lengths of 23 and 25 carbons in males (mainly with one double bond) and 27 and 29 carbons in females (mainly with two double bonds). here, we describe an elongase gene, elof, with female-biased expression. the 771-bp orf encodes a 257-aa protein that shows the highest sequence identity with mouse ssc1 elongase (3 ...200717360514
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 ...200312559491
from parasite to mutualist: rapid evolution of wolbachia in natural populations of drosophila.wolbachia are maternally inherited bacteria that commonly spread through host populations by causing cytoplasmic incompatibility, often expressed as reduced egg hatch when uninfected females mate with infected males. infected females are frequently less fecund as a consequence of wolbachia infection. however, theory predicts that because of maternal transmission, these "parasites" will tend to evolve towards a more mutualistic association with their hosts. drosophila simulans in california provi ...200717439303
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 ...200212652910
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 ...200212051989
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 ...200414508499
sebida: a database for the functional and evolutionary analysis of genes with sex-biased expression.we describe sebida, a database of genes with sex-biased expression. the database integrates results from multiple, independent microarray studies comparing male and female gene expression in drosophila melanogaster, drosophila simulans and anopheles gambiae. sebida uses standard nomenclature, which allows individual genes to be compared across different microarray platforms and to be queried by gene name, symbol, or annotation number. in addition to ratios of male/female expression for each gene ...200616882652
induced paternal effects mimic cytoplasmic incompatibility in drosophila.wolbachia is an intracellular microbe found in a wide diversity of arthropod and filarial nematode hosts. in arthropods these common bacteria are reproductive parasites that manipulate central elements of their host's reproduction to increase their own maternal transmission in one of several ways. cytoplasmic incompatibility (ci) is one such manipulation where sperm are somehow modified in infected males and this modification must be rescued by the presence of the same bacterial strain in the eg ...200616489228
wolbachia infection influences the development of culex pipiens embryo in incompatible crosses.wolbachia are maternally inherited endosymbiotic bacteria that infect many arthropod species and have evolved several different ways for manipulating their host, the most frequent being cytoplasmic incompatibility (ci). ci leads to embryo death in crosses between infected males and uninfected females, as well as in crosses between individuals infected by incompatible wolbachia strains. in the mosquito culex pipiens, previous studies suggested developmental variation in embryos stemming from diff ...200616639421
wolbachia infection alters olfactory-cued locomotion in drosophila spp.wolbachia pipientis is an endosymbiotic bacterium present in diverse insect species. although it is well studied for its dramatic effects on host reproductive biology, little is known about its effects on other aspects of host biology, despite its presence in a wide array of host tissues. this study examined the effects of three wolbachia strains on two different drosophila species, using a laboratory performance assay for insect locomotion in response to olfactory cues. the results demonstrate ...200818456851
genetic and functional characterization of the type iv secretion system in wolbachia.a type iv secretion system (t4ss) is used by many symbiotic and pathogenic intracellular bacteria for the successful infection of and survival, proliferation, and persistence within hosts. in this study, the presence and function of the t4ss in wolbachia strains were investigated by a combination of genetic screening and immunofluorescence microscopy. two operons of virb-vird4 loci were found in the genome of wolbachia pipientis strain watab3, from the hymenoptera asobara tabida, and strain wri, ...200818502862
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 ...200415254259
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 ...200415088643
wolbachia infection reduces sperm competitive ability in an insect.the maternally inherited bacterium wolbachia pipientis imposes significant fitness costs on its hosts. one such cost is decreased sperm production resulting in reduced fertility of male drosophila simulans infected with cytoplasmic incompatibility (ci) inducing wolbachia. we tested the hypothesis that wolbachia infection affects sperm competitive ability and found that wolbachia infection is indeed associated with reduced success in sperm competition in non-virgin males. in the second male role, ...200616777737
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 ...200415088657
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 ...200415088659
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 ...200415088660
wolbachia interferes with ferritin expression and iron metabolism in insects.wolbachia is an intracellular bacterium generally described as being a facultative reproductive parasite. however, wolbachia is necessary for oogenesis completion in the wasp asobara tabida. this dependence has evolved recently as a result of interference with apoptosis during oogenesis. through comparative transcriptomics between symbiotic and aposymbiotic individuals, we observed a differential expression of ferritin, which forms a complex involved in iron storage. iron is an essential element ...200919851452
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 ...200414660690
monitoring long-term evolutionary changes following wolbachia introduction into a novel host: the wolbachia popcorn infection in drosophila simulans.wolbachia may act as a biological control agent for pest management; in particular, the wolbachia variant wmelpop (popcorn) shortens host longevity and may be useful for dengue suppression. however, long-term changes in the host and wolbachia genomes can alter wolbachia spread and/or host effects that suppress disease. here, we investigate the phenotypic effects of wmelpop in a non-native host, drosophila simulans, following artificial transinfection approximately 200 generations ago. long-term ...201020219740
nuclear-mitochondrial epistasis and drosophila aging: introgression of drosophila simulans mtdna modifies longevity in d. melanogaster nuclear backgrounds.under the mitochondrial theory of aging, physiological decline with age results from the accumulated cellular damage produced by reactive oxygen species generated during electron transport in the mitochondrion. a large body of literature has documented age-specific declines in mitochondrial function that are consistent with this theory, but relatively few studies have been able to distinguish cause from consequence in the association between mitochondrial function and aging. since mitochondrial ...200616219776
artificial triple wolbachia infection in aedes albopictus yields a new pattern of unidirectional cytoplasmic incompatibility.obligately intracellular wolbachia bacteria infect numerous invertebrates and often manipulate host reproduction to facilitate the spread of infection. an example of reproductive manipulation is wolbachia-induced cytoplasmic incompatibility (ci), which occurs commonly in insects. this ci has been the focus both of basic scientific studies of naturally occurring invasion events and of applied investigations on the use of wolbachia as a vehicle to drive desired genotypes into insect populations (" ...201020601501
evolution of gene expression in the drosophila olfactory system.host plant shifts by phytophagous insects play a key role in insect evolution and plant ecology. such shifts often involve major behavioral changes as the insects must acquire an attraction and/or lose the repulsion to the new host plant's odor and taste. the evolution of chemotactic behavior may be due, in part, to gene expression changes in the peripheral sensory system. to test this hypothesis, we compared gene expression in the olfactory organs of drosophila sechellia, a narrow ecological sp ...200818296696
infection with the wmel and wmelpop strains of wolbachia leads to higher levels of melanization in the hemolymph of drosophila melanogaster, drosophila simulans and aedes aegypti.introduction of the life-shortening strain of wolbachia pipientis, wmelpop, into the key dengue vector, aedes aegypti, and the anti-pathogen effects in wolbachia-infected hosts highlights the need for more research into its interactions with its original host, drosophila melanogaster, and the novel mosquito host. the visual difference in darkness between the eggs of wmelpop wolbachia-infected and uninfected mosquito hosts after egg deposition led to further investigation into melanization levels ...201021075139
wolbachia infections in anopheles gambiae cells: transcriptomic characterization of a novel host-symbiont interaction.the endosymbiotic bacterium wolbachia is being investigated as a potential control agent in several important vector insect species. recent studies have shown that wolbachia can protect the insect host against a wide variety of pathogens, resulting in reduced transmission of parasites and viruses. it has been proposed that compromised vector competence of wolbachia-infected insects is due to up-regulation of the host innate immune system or metabolic competition. anopheles mosquitoes, which tran ...201121379333
sympatric drosophila simulans flies with distinct mtdna show difference in mitochondrial respiration and electron transport.the role of mitochondrial dna (mtdna) in mitochondrial metabolism is understudied yet humans harboring specific mtdna types age at dissimilar rates, are unequally susceptible to various diseases, and differentially adapt to various environmental conditions. this study compares mitochondrial respiration, proton leak and electron transport of drosophila simulans males with distinct mtdna haplogroups (siii and -iii) that were collected in sympatry in kenya. despite the large divergence among haplog ...200717296496
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 ...200415521450
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