Publications

hidden effects of x chromosome introgressions on spermatogenesis in drosophila simulans x d. mauritiana hybrids unveiled by interactions among minor genetic factors.	one of the most frequent outcomes of interspecific hybridizations in drosophila is hybrid male sterility. genetic dissection of this reproductive barrier has revealed that the number of responsible factors is very high and that these factors are frequently engaged in complex epistatic interactions. traditionally, research strategies have been based on contrasting introgressions of chromosome segments that produce male sterility with those that allow fertility. few studies have investigated the p ...	1998	9755205
describing the evolution of reaction norm shape: body pigmentation in drosophila.	if phenotypic plasticity is a trait subject to selection and evolution, we need to quantify reaction norms and to identify the potential target(s) of selection. previously we proposed the use of polynomial coefficients as reaction norm descriptors. however, the interpretation of these coefficients is not straightforward if the reaction norm is not linear. therefore, we instead propose the use of characteristic values to describe reaction norms. we depict such characteristic values for linear, qu ...	1998	28565397
cytological characterization of premeiotic versus postmeiotic defects producing hybrid male sterility among sibling species of the drosophila melanogaster complex.	in accordance with haldane's rule, hybridizations between species of the drosophila simulans clade produce fertile females but sterile males. in this study, a comprehensive characterization was undertaken on the six types of f1 males that were the result of the crosses between d. simulans, d. sechellia, and d. mauritiana. with the use of light and electron microscopy, it was shown that while each particular hybrid genotype exhibited a specific sterility phenotype, these phenotypes fell into two ...	1998	28565214
duplication of the rdl gaba receptor subunit gene in an insecticide-resistant aphid, myzus persicae.	resistance to cyclodiene insecticides is associated with replacements of a single amino acid (alanine 302) in a gamma-aminobutyric acid (gaba) receptor subunit encoded by the single-copy gene resistance to dieldrin (rdl). alanine 302 is predicted to reside within the second membrane-spanning region of the rdl receptor, a region that is thought to line the integral chloride ion channel pore. in all cyclodiene-resistant insects studied to date, this same alanine residue is replaced either by a ser ...	1998	9862468
characterization of a hypermutable strain of drosophila simulans.	a hypermutable strain of drosophila simulans that originated from a single spontaneous mutant male was characterized. seven different mutations were isolated from roughly 100 generations of offspring. the genetic analysis of the viable mutants showed two mutations on the x chromosome, one in the lozenge locus and the other in the ruby gene. the autosomic mutations characterized were a dpp-heldout-like, a blistered-like and a homoeotic dominant mutant with an antenna-to-leg transformation and ect ...	1998	9849620
a temperature cline in copy number for 412 but not roo/b104 retrotransposons in populations of drosophila simulans.	the copy number of the retrotransposable element 412 of drosophila simulans from populations collected worldwide shows a negative correlation with minimum temperature. no association was detected for the roo/b104 element. the possibility that selective pressures might regulate the 412 copy number in these natural populations is supported by detection of selection against the detrimental effects of 412 insertions (estimated by the proportion of insertions on the x chromosome in comparison with th ...	1998	9699309
genetics of hybridization between drosophila simulans females and d. melanogaster males.	drosophila simulans and d. melanogaster are sibling cosmopolitan species with imperfect ethological isolation. hybridization is easy between d. melanogaster females and d. simulans males, but the reciprocal cross has been traditionally considered as very scarce and little is known about the environmental and genetic factors that affect it. we used classical genetic analyses to determine the influence of each major chromosome on the breakdown of sexual isolation between females of d. simulans and ...	1998	9474773
codon bias evolution in drosophila. population genetics of mutation-selection drift.	although non-random patterns of synonymous codon usage are a prominent feature in the genomes of many organisms, the relatives roles of mutational biases and natural selection in maintaining codon bias remain a contentious issue. in some species, patterns of codon bias and empirical findings on the biology of translation suggest 'major codon preference', a balance among mutation pressure, genetic drift, and weak selection in favor of translationally superior codons. population genetics theory ma ...	1997	9461401
the sex-ratio trait in drosophila simulans: genetic analysis of distortion and suppression.	the sex-ratio trait described in several drosophila species is a type of naturally occurring x-linked meiotic drive that causes males bearing a sex-ratio x chromosome to produce progenies with a large excess of females. we have previously reported the occurrence of sex-ratio x chromosomes in drosophila simulans. in this species, because of the co-occurrence of drive suppressors, the natural populations and the derived laboratory strains show an equal sex-ratio even when sex-ratio x chromosomes a ...	1997	9335600
chromosomal distribution of the 412 retrotransposon in natural populations of drosophila simulans.	the insertion site localization of the 412 retrotransposable element was analysed by in situ hybridization to the polytene chromosomes of 57 individual genomes from 25 natural populations of drosophila simulans. the 412 insertion sites along the chromosomes show a tendency to aggregate in the distal and proximal ends of the 2r arm, and in several local regions along the 3r arm. the distribution of the 412 insertion sites, weighted by dna content, along the chromosome arms reveals an overall tend ...	1997	9279009
genetic basis of sperm and testis length differences and epistatic effect on hybrid inviability and sperm motility between drosophila simulans and d. sechellia.	results are reported from a genetic study of hybrid inviability and three 'fertilization traits' (sperm motility and length, and testis size) that affect hybrid sterility between the sibling species drosophila simulans and d. sechellia. the main findings are as follows. (i) for sperm length there was a dominant effect of the d. simulans genome over that of d. sechellia, and the y chromosome of d. sechellia in the background of d. simulans reduced the sperm length. (ii) in contrast, testis length ...	1997	9134705
an introgression analysis of quantitative trait loci that contribute to a morphological difference between drosophila simulans and d. mauritiana.	drosophila simulans and d. mauritiana differ markedly in morphology of the posterior lobe, a male-specific genitalic structure. both size and shape of the lobe can be quantified by a morphometric variable, pcl, derived from principal components and fourier analyses. the genetic architecture of the species difference in pcl was investigated previously by composite interval mapping, which revealed largely additive inheritance, with a minimum of eight quantitative trait loci (qtl) affecting the tra ...	1997	9071588
transposition rate of the 412 retrotransposable element is independent of copy number in natural populations of drosophila simulans.	the transposition and excision rates of the 412 retrotransposable element were estimated in five populations of drosophila simulans differing in their average 412 copy numbers, which ranged from 2 to 54. the transposition rate was found to equal 1 x 10(-3) to 2 x 10(-3), independently of copy number. no excision was detected. these values eliminate autoregulation as a force maintaining copy number of the 412 element in natural populations of d. simulans.	1997	9029796
conceptual translation of timeless reveals alternative initiating methionines in drosophila.	we have sequenced genomic fragments which encode the n-terminus of the timeless (tim) clock protein in drosophila simulans and d. yakuba. we observe that in these two species, the initiating methionine appears to lie downstream of the one proposed to encode the translational start ind.melanogaster, thereby truncating the n-terminus by 23 amino acids. we then sequenced the corresponding 5'fragment in a number of d. melanogaster individuals from different strains. we observed a polymorphism which ...	1997	9016581
quantitative genetic analysis of divergence in male secondary sexual traits between drosophila simulans and drosophila mauritiana.	the sibling species drosophila simulans and d. mauritiana differ significantly in a number of male secondary sexual traits, providing an ideal system for genetic analysis of interspecific morphological divergence. in the experiment reported here, f1 hybrids from a cross of two inbred lines were backcrossed in both directions and about 200 flies from each backcross were scored for several traits (bristle numbers and cuticle areas), as well as 18 markers distributed throughout the genome. each tra ...	1997	28568599
the sex-ratio trait in drosophila simulans: geographical distribution of distortion and resistance.	the sex-ratio trait we describe here in drosophila simulans results from x-linked meiotic drive. males bearing a driving x chromosome can produce a large excess of females (about 90%) in their progeny. this is, however, rarely the case in the wild, where resistance factors, including autosomal suppressors and insensitive y chromosomes, prevent the expression of the driver. in this study, we searched for drive and resistance factors in strains of drosophila simulans collected all over the world. ...	1997	28565112
adaptation and specialization in a two-resource environment in drosophila species.	we assayed two components of performance (development time and survivorship), on food medium with and without ethanol, in laboratory populations of drosophila simulans and d. melanogaster for which ethanol-medium was a novel food resource. these assays were done before and after 12 generations of rearing in either one-(regular medium only) or two-resource (regular medium and ethanol medium) environments. initially, d. simulans was highly susceptible to ethanol, whereas d. melanogaster was relati ...	1997	28568582
wolbachia infection in drosophila simulans: does the female host bear a physiological cost?	fitness traits of three drosophila simulans strains infected by endocellular bacteria belonging to the genus wolbachia have been compared with those of replicate stocks previously cured from the infection by an antibiotic treatment. the traits measured were development time, egg-to-adult viability, egg hatch, productivity, fecundity, and the number of functional ovarioles. individuals of the first strain were bi-infected by two wolbachia variants, wha and wno. the second strain was infected by w ...	1997	28568785
nonrandom partition of mitochondria in heteroplasmic drosophila.	in order to understand the status of heteroplasmy and its evolution within the drosophila melanogaster subgroup, cytoplasm microinjections between eggs were performed involving three lineages of drosophila simulans, carrying the sii, siii or siiii mtdna type, respectively, and two strains of drosophila mauritiana carrying the mai or maii mtdna type. progeny of eggs from all combinations of injection were analysed. the maii or sii molecules, when provided by the donor, were never detected in the ...	1997	9418268
nucleotide sequence divergence in the a+t-rich region of mitochondrial dna in drosophila simulans and drosophila mauritiana.	we have determined the nucleotide sequences of two regions within the a+t-rich region of mitochondrial dna (mtdna) in the siiii type of drosophila simulans and the mai type of d. mauritiana. the sequences of the two regions in siiii and mai are almost identical. the sequences include elements corresponding to the type i and type ii repeats elements and the t-stretches as reported in d. melanogaster; an approximately 340-bp region (a region) adjacent to the trna(ile) gene includes a part of the t ...	1997	9254919
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 ...	1997	9281403
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 ...	1997	9044057
behavior of wolbachia endosymbionts from drosophila simulans in drosophila serrata, a novel host.	many species harbor the incompatibility-inducing microbe wolbachia, a maternally inherited endoparasite that causes reduced egg hatch in crosses between infected males and uninfected females. infected females are immune to this effect, which gives them a relative fitness advantage that results in the spread of the infection. the strength of incompatibility, fitness deficits associated with the infection, and transmission rate from mother to offspring largely determine the rate and extent of spre ...	1997	18811258
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 ...	1996	8978041
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 ...	1996	8817452
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 ...	1996	8575931
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 ...	1996	8856030
naturally occurring variation in copia expression is due to both element (cis) and host (trans) regulatory variation.	significant differences in levels of copia [drosophila long terminal repeat (ltr) retrotransposon] expression exist among six species representing the drosophila melanogaster species complex (d. melanogaster, drosophila mauritiana, drosophila simulans, drosophila sechellia, drosophila yakuba, and drosophila erecta) and a more distantly related species (drosophila willistoni). these differences in expression are correlated with major size variation mapping to putative regulatory regions of the co ...	1996	8692951
a genome-wide survey of hybrid incompatibility factors by the introgression of marked segments of drosophila mauritiana chromosomes into drosophila simulans.	in hybrids between drosophila simulans and d. mauritiana, males are sterile and females are fertile, in compliance with haldane's rule. the genetic basis of this phenomenon was investigated by introgression of segments of the mauritiana genome into a simulans background. a total of 87 positions throughout the mauritiana genome were marked with p-element insertions and replicate introgressions were made by repeated backcrossing to simulans for 15 generations. the fraction of hemizgyous x chromoso ...	1996	8849890
genetics and the environment in interspecific competition: a study using the sibling species drosophila melanogaster and drosophila simulans.	the outcome of interspecific competition of two closely related species may depend upon genetic variation in the two species and the environment in which the experiment is carried out. interspecific competition in the two sibling species, drosophila melanogaster and d. simulans, is usually investigated using longterm laboratory stocks that often have mutant markers that distinguish them. to examine competition in flies that genetically more closely resemble flies in nature, we utilized freshly c ...	1996	28307735
genetics of a difference in male cuticular hydrocarbons between two sibling species, drosophila simulans and d. sechellia.	in seven of the eight species of the drosophila melanogaster group, the predominant cuticular hydrocarbon of males is 7-tricosene, but in the island endemic species d. sechellia it is 6-tricosene. the phylogeny of the group implies that the novel hydrocarbon profile of d. sechellia is a derived character. genetic analysis of hybrids between d. sechellia and its close relative d. simulans show that each of the five major chromosome arms carries at least one gene affecting the ratio of the two tri ...	1996	8844156
evolutionary changes in the expression pattern of a developmentally essential gene in three drosophila species.	the hypothesis that morphological evolution may largely result from changes in gene regulation rather than gene structure has been difficult to test. morphological differences among insects are often apparent in the cuticle structures produced. the dopa decarboxylase (ddc) and alpha-methyldopa hypersensitive (amd) genes arose from an ancient gene duplication. in drosophila, they have evolved nonoverlapping functions, including the production of distinct types of cuticle, and for ddc, the product ...	1996	8692952
indirect evidence of alteration in the expression of the rdna genes in interspecific hybrids between drosophila melanogaster and drosophila simulans.	crosses between drosophila melanogaster females and d. simulans males produce viable hybrid females, while males are lethal. these males are rescued if they carry the d. simulans lhr gene. this paper reports that females of the wild-type d. melanogaster population staket do not produce viable hybrid males when crossed with d. simulans lhr males, a phenomenon which we designate as the staket phenotype. the agent responsible for this phenomenon was found to be the staket x chromosome (xmel, stk). ...	1996	8569692
evolution of broad and specific competitive ability in novel versus familiar environments in drosophila species.	we used nine pairs of competing drosophila melanogaster and drosophila simulans populations to test three hypotheses. (1) weaker competitors undergo greater evolutionary increases in competitive ability, compared with stronger ones. (2) increased competitive ability against a specific competitor population causes a correlated increase in competitive ability against other competitor populations. (3) in a novel environment, adaptation to the abiotic environment contributes more to competitive abil ...	1996	28568885
growth temperature and adult pigmentation in two drosophila sibling species: an adaptive convergence of reaction norms in sympatric populations?	phenotypic plasticity of abdomen pigmentation was investigated in populations of the sibling species drosophila melanogaster and d. simulans, living in sympatry in two french localities. ten isofemale lines of each population and species were grown at different constant temperatures spanning their complete thermal range from 12 to 31°c. genetic variability between isofemale lines was not affected by growth temperature, but was consistently less in d. simulans. for all traits, the dark pigmentati ...	1996	28565663
genetics of sexual isolation in male hybrids of drosophila simulans and d. mauritiana.	sexual isolation between the sibling species d. simulans and d. mauritiana is due largely to the rejection of d. simulans males by d. mauritiana females. genetic analysis shows that genes on the x and third chromosomes contribute to the differences between males causing sexual isolation, while the y chromosome, second chromosome and cytoplasm have no effect. these chromosome effects differ from those observed in a previous analysis of sexual isolation in hybrid females, implying that different g ...	1996	9062078
population genetics of silent and replacement variation in drosophila simulans and d. melanogaster: x/autosome differences?		1996	8952085
somatic activity of the mariner transposable element in natural populations of drosophila simulans.	the characteristics of the mariner transposable element in natural populations of drosophila simulans from different parts of the world were analysed. the somatic excision rate (estimated from a test-cross with a reference strain), the average number of copies (determined by southern blots), and the presence of deleted copies (detected by polymerase chain reaction amplification) were estimated for each population. there was a great variability in the somatic excision rate, measured as the percen ...	1996	8952091
discord between the phylogenies inferred from molecular versus functional data: uneven rates of functional evolution or low levels of gene flow?	according to measures of molecular divergence, the three species of the drosophila simulans clade are closely related to and essentially equidistant from each other. we introgressed 10% of the d. sechellia x chromosome into a pure d. simulans genetic background and found that males carrying this introgressed region were consistently fertile; in contrast, males carrying the same segment from d. mauritiana are sterile and suffer from incompatibilities at a minimum of four loci. together with other ...	1996	8913771
high nucleotide sequence variation in a region of low recombination in drosophila simulans is consistent with the background selection model.	we surveyed nucleotide sequence variation at glucose dehydrogenase (gld), in a region of low recombination on chromosome 3r, from a population sample of drosophila simulans. the levels of nucleotide variation were surprisingly high. there was no departure from the expectation of a neutral model for the level of polymorphism, indicating no evidence of a selective sweep in this region. there was a significant deficiency of singleton polymorphisms according to the fu and li test, although tajima an ...	1996	8865667
the genetics of reproductive isolation in the drosophila simulans clade: x vs. autosomal effects and male vs. female effects.	a strong effect of homozygous autosomal regions on reproductive isolation was found for crosses between the species in the drosophila simulans clade. second chromosome regions were introgressed from d. mauritiana and d. sechellia into d. simulans and tested for their homozygous effects on hybrid male and hybrid female sterility and inviability. most introgressions are fertile as heterozygotes, yet produce sterile male offspring when made homozygous. the density of homozygous autosomal factors co ...	1996	8807297
the relationship between structural variation and dysgenic properties of p elements in long-established p-transformed lines of drosophila simulans.	ten lines of drosophila simulans were investigated with respect to p activity, p susceptibility and the number and structure of their p copies, eight years after transformation with the p element. all 10 were found to have reached a steady state. they exhibited varying levels of p activity (from 0 per cent to 96 per cent gd sterility) and, with the exception of one line, were not p-susceptible. in contrast with p element behaviour in d. melanogaster: (i) no relationship was found between the mol ...	1996	8682694
cytoplasmic incompatibility in drosophila simulans: evolving complexity.		1996	21237786
genetic analysis of a morphological shape difference in the male genitalia of drosophila simulans and d. mauritiana.	two closely related species of drosophila, d. simulans and d. mauritiana, differ markedly in morphology of the posterior lobe of the male genital arch. both size and shape aspects of lobe variation can be quantified by a morphometric descriptor based on elliptical fourier and principal components analyses. the genetic architecture of this quantitative trait (pc1) was investigated by hybridizing inbred lines to produce two backcross populations approximately 200 individuals each, which were analy ...	1996	8846893
geographical variation in insertion site number of retrotransposon 412 in drosophila simulans.	the insertion site number of the retrotransposable element 412 was analyzed in natural populations of drosophila simulans of worldwide origin by in situ hybridization. we observe a gradient in copy number ranging from as high as 23 in europe to 1-10 in south africa, while populations in madagascar and the indian islands, which are the cradle of d. simulans, have only 3-7 copies. we find very different copy numbers in some local populations of australia and the pacific islands (with around 60 cop ...	1996	8642613
molecular structure of the transposable element ninja in drosophila simulans.	genetically unstable dna sequences of 16.1 kb in length were isolated from the white locus of the w(mky) strain of drosophila simulans. this insertional dna has some unique characteristics as a transposon. it is found in high numbers in this strain and its revertant strains w(psm1) and w(cho), but not elsewhere, and the sequence is a tandem triplication of a basic repeating unit. in order to determine the structure of the insert as whole and the functional unit as a transposon, we analyzed nine ...	1996	8925473
genetic studies on premating isolation in drosophila simulans. i.ad. simulans line highly crossable with d. melanogaster.	the s2 line of drosophila simulans, an isofemale line from a natural population at mishima, japan, was found to have high crossability with d. melanogaster. over 80% of the s2 females mated with d. melanogaster males, while only 2.4- 14.2% of control females from other d. simulans lines mated. the reciprocal mating (d. melanogaster female x s2 males) was in normal range (35-50%). the crossability of the f1 females between the s2 and other normal simulans lines was slightly higher than the contro ...	1995	7632441
haplotype test reveals departure from neutrality in a segment of the white gene of drosophila melanogaster.	restriction map studies previously revealed extensive linkage disequilibria in the transcriptional unit of the white locus in natural drosophila melanogaster populations. to understand the causes of these disequilibria, we sequenced a 4722-bp region of the white gene from 15 lines of d. melanogaster and 1 line of drosophila simulans. statistical tests applied to the entire 4722-bp region do not reject neutrality. in contrast, a test for high-frequency haplotypes ("haplotype test") revealed an 83 ...	1995	8601488
evolutionary dynamics of the enhancer region of even-skipped in drosophila.	we report findings on naturally occurring variation in the regulatory region of even-skipped in drosophila. this pair-rule gene encodes a homeobox-containing transcription factor, is expressed as a series of seven transverse stripes in developing embryos, and defines parasegmental boundaries. the 5' flanking region of the gene contains a 671-bp enhancer governing stripe 2 expression. the stripe 2 enhancer contains multiple binding sites for four transcription factors that provide positional info ...	1995	8524036
localization of pheromonal sexual dimorphism in drosophila melanogaster and its effect on sexual isolation.	drosophila melanogaster is sexually dimorphic for cuticular hydrocarbons, with males and females having strikingly different profiles of the long-chain compounds that act as contact pheromones. gas-chromatographic analysis of sexual mosaics reveals that the sex specificity of hydrocarbons is located in the abdomen. this explains previous observations that d. melanogaster males display the strongest courtship toward mosaics with female abdomens. we also show that males of the sibling species dros ...	1995	7568163
the distribution of transposable elements on x chromosomes from a natural population of drosophila simulans.	the distribution of 13 transposable element families along 15 x chromosomes from an african natural population of drosophila simulans was determined by in situ hybridization to polytene chromosomes. the transposable elements cloned from drosophila melanogaster all hybridized with drosophila simulans chromosomes. the number of copies per family was 3.5 times lower in the latter species and correlated with the copy number per family in drosophila melanogaster. with the exception of 297, the copy n ...	1995	8522157
somatic movement of the mariner transposable element and lifespan of drosophila species.	the effect of somatic movement of the mariner transposable element on lifespan was measured in drosophila simulans and drosophila melanogaster males at 25 degrees c. in d. simulans this movement significantly decreased lifespan, whereas in d. melanogaster no correlation between transposon movement and lifespan was found. the results in d. simulans support the hypothesis that somatic genetic damage induced by dna element movement can reduce lifespan.	1995	7565881
nucleotide polymorphism in the 5' promoter region of esterase 6 in drosophila melanogaster and its relationship to enzyme activity variation.	a 974-bp region immediately 5' of the esterase 6 gene was sequenced in 17 field derived third chromosome isoallelic lines. twenty-three polymorphisms were identified, only two in the first 400 bp 5' but 16 in a 325-bp region from -494 to -819 bp. this distribution differs from previously published patterns in drosophila simulans and d. mauritiana, where the first 800 bp are highly conserved. fourteen common polymorphisms in the 325-bp region above are all in strong linkage disequilibrium with ea ...	1995	8536969
inferring weak selection from patterns of polymorphism and divergence at "silent" sites in drosophila dna.	patterns of codon usage and "silent" dna divergence suggest that natural selection discriminates among synonymous codons in drosophila. "preferred" codons are consistently found in higher frequencies within their synonymous families in drosophila melanogaster genes. this suggests a simple model of silent dna evolution where natural selection favors mutations from unpreferred to preferred codons (preferred changes). changes in the opposite direction, from preferred to unpreferred synonymous codon ...	1995	7713409
the distribution of the transposable element bari-1 in the drosophila melanogaster and drosophila simulans genomes.	the distribution of the transposable element bari-1 in d. melanogaster and d. simulans was examined by southern blot analysis and by in situ hybridization in a large number of strains of different geographical origins and established at different times. bari-1 copies mostly homogeneous in size and physical map are detected in all strains tested. both in d. melanogaster and in d. simulans a relatively high level of intraspecific insertion site polymorphism is detectable, suggesting that in both s ...	1995	8522166
nucleotide variation at the hypervariable esterase 6 isozyme locus of drosophila simulans.	esterase 6 (est-6/est6) is polymorphic in both drosophila melanogaster and d. simulans for two common allozyme forms, as well as for several other less common variants. parallel latitudinal clines in the frequencies of the common est6-f and est6-s allozymes in these species have previously been interpreted in terms of a shared amino acid polymorphism that distinguishes the two variants and is subject to selection. here we compare the sequences of four d. simulans est-6 isolates and show that ove ...	1995	7877486
malathion resistance levels in sympatric populations of drosophila simulans (diptera: drosophilidae) and d. melanogaster differ by two orders of magnitude.	malathion resistance levels were determined in populations of the sympatric species drosophila melanogaster (meigen) and drosophila simulans (sturtevant) from a collection site in tampa bay, fl, with a 20+ yr history of intensive malathion exposure. bioassays of insecticide resistance were done by using a desiccation technique that reduces both the effects of avoidance behavior on the results and the total time of the assay. resistance levels in isofemale lines of d. simulans are as much as 2 or ...	1995	7593892
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 ...	1995	7759292
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 ...	1995	7604001
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 ...	1995	7498773
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 ...	1995	8587875
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 ...	1995	8582608
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 ...	1994	8138153
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 ...	1994	7906391
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 ...	1994	7894745
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 ...	1994	8005448
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 ...	1994	8200813
molecular evolution of the metallothionein gene mtn in the melanogaster species group: results from drosophila ananassae.	three distinctly different alleles of the metallothionein gene mtn have been identified in natural drosophila melanogaster populations: mtn.3, mtn1, and dp(mtn1), where the latter designates a tandem duplication of mtn1. in drosophila simulans, only mtn.3-type alleles have been found. it has been suggested that mtn.3 is the ancestral allele and demonstrated that a presumed two-step transition from mtn.3 to mtn1 to dp(mtn1) is accompanied by an approximate 5-fold increase in rna levels. we analyz ...	1994	8001781
evidence for complex genic interactions between conspecific chromosomes underlying hybrid female sterility in the drosophila simulans clade.	f1 hybrid females between the sibling species drosophila simulans, drosophila mauritiana and drosophila sechellia are completely fertile. however, we have found that female sterility can be observed in f2 backcross females who are homozygous for d. simulans x chromosomes and homozygous for autosomal regions from either d. mauritiana or d. sechellia. our results indicate that neither d. mauritiana autosome (2 or 3) can cause complete female sterility in a d. simulans background. the simultaneous ...	1994	8056310
genetics of reproductive isolation in the drosophila simulans clade: complex epistasis underlying hybrid male sterility.	we have analyzed the sterility associated with introgressions of the distal one-fourth of the x chromosome from either drosophila mauritiana or drosophila sechellia into the genome of drosophila simulans using a series of visible and dna markers. because in drosophila hybrids, male sterility is usually complete and is often tightly linked with each of several markers used in crosses, a simple genetic basis has generally been assumed. in our low resolution mapping experiment, we were not able to ...	1994	8056308
genetics of hybrid male sterility between drosophila sibling species: a complex web of epistasis is revealed in interspecific studies.	to study the genetic differences responsible for the sterility of their male hybrids, we introgressed small segments of an x chromosome from drosophila simulans into a pure drosophila mauritiana genetic background, then assessed the fertility of males carrying heterospecific introgressions of varying size. although this analysis examined less than 20% of the x chromosome (roughly 5% of the euchromatic portion of the d. simulans genome), and the segments were introgressed in only one direction, a ...	1994	7828817
clonal analysis in hybrids between drosophila melanogaster and drosophila simulans.	we have analysed the viability of cellular clones induced by mitotic recombination in drosophila melanogaster/d. simulans hybrid females during larval growth. these clones contain a portion of either melanogaster or simulans genomes in homozygosity. analysis has been carried out for the x and the second chromosomes, as well as for the 3l chromosome arm. clones were not found in certain structures, and in others they appeared in a very low frequency. only in abdominal tergites was a significant n ...	1994	28305934
unraveling selection in the mitochondrial genome of drosophila.	we examine mitochondrial dna variation at the cytochrome b locus within and between three species of drosophila to determine whether patterns of variation conform to the predictions of neutral molecular evolution. the entire 1137-bp cytochrome b locus was sequenced in 16 lines of drosophila melanogaster, 18 lines of drosophila simulans and 13 lines of drosophila yakuba. patterns of variation depart from neutrality by several test criteria. analysis of the evolutionary clock hypothesis shows uneq ...	1994	7851772
meiosis in drosophila males. i. the question of separate conjunctive mechanisms for the xy and autosomal bivalents.	the conjunctive mechanism of the xy bivalent is believed to differ from that of the autosomal bivalents in the achiasmate drosophila melanogaster male. it has been proposed that hypothetical cohesive elements, termed collochores, hold the x and y chromosomes together at or near their nucleolar organizing regions (nors) and that collochores are not exhibited by autosomal bivalents. in electron micrographs, unique fibrillar material is observed between the x and y chromosomes at the synaptic site. ...	1994	7821091
neutral and non-neutral evolution of drosophila mitochondrial dna.	to test hypotheses of neutral evolution of mitochondrial dna (mtdna), nucleotide sequences were determined for 1515 base pairs of the nadh dehydrogenase subunit 5 (nd5) gene in the mitochondrial dna of 29 lines of drosophila melanogaster and 9 lines of its sibling species drosophila simulans. in contrast to the patterns for nuclear genes, where d. melanogaster generally exhibits much less nucleotide polymorphism, the number of segregating sites was slightly higher in a global sample of nine nd5 ...	1994	7851771
genetic and maternal variation for heat resistance in drosophila from the field.	in drosophila, field heritability estimates have focused on morphological traits and ignored maternal effects. this study considers heritable variation and maternal effects in a physiological trait, heat resistance. drosophila were collected from the field in melbourne, australia. resistance was determined using knock-down time at 37 degrees. drosophila melanogaster was more resistant than drosophila simulans, and males tended to be more resistant than females. field heritability and maternal ef ...	1994	8088524
differences in p element population dynamics between the sibling species drosophila melanogaster and drosophila simulans.	patterns of p element establishment and evolution were compared in populations of d. melanogaster and d. simulans. for each species, mixed populations were initiated with m strain flies lacking p elements together with p strain flies having similar p element copy numbers and phenotypes. the mixed populations were subsequently maintained under similar environmental conditions. on the basis of gonadal sterility assays, p elements tended to be significantly more active in d. melanogaster than in d. ...	1994	8206365
the doc transposable element in drosophila melanogaster and drosophila simulans: genomic distribution and transcription.	the mobile element doc is similar in structure and coding potential to the line families found in various organisms. in this paper, we analyze the insertional and structural polymorphism of this element and show that it appears to have a long evolutionary history in the genome of d. melanogaster. like the family of i elements, the doc family seems to display three types of elements: full length elements, defective members that have recently transposed and long since immobilized members common to ...	1994	7813908
molecular polymorphism in the period gene of drosophila simulans.	the threonine-glycine (thr-gly) repeat region of the period (per) gene of eight natural populations of drosophila simulans from europe and north africa was analyzed by polymerase chain reaction, dna sequencing and heteroduplex formation. five different length alleles encoding 21, 23, 25 and two different kinds of 24 thr-gly pairs in the uninterrupted repeat were found. in the 3' region flanking the repeat 6 nucleotide substitutions (3 synonymous, 3 replacement) were observed in three different c ...	1994	7851767
nuclear background affects frequency dynamics of mitochondrial dna variants in drosophila simulans.	transplasmic lines, in which the original mitochondrial dna (mtdna) had been completely replaced by the mtdna of the donor, were constructed to test for selection on mtdna variants and to investigate the effects of nuclear-cytoplasmic interactions in drosophila simulans. these lines were used to set up 12 experimental populations putting in competition two mtdna variants with two different starting frequencies. population cages were maintained for 20 generations and periodically sampled to monit ...	1994	8056616
evolution of incompatibility-inducing microbes and their hosts.	in many insect species, males infected with microbes related to wolbachia pipientis are "incompatible" with uninfected females. crosses between infected males and uninfected females produce significantly fewer adult progeny than the other three possible crosses. the incompatibility-inducing microbes are usually maternally transmitted. thus, incompatibility tends to confer a reproductive advantage on infected females in polymorphic populations, allowing these infections to spread. this paper anal ...	1994	28568404
a multilevel approach to the significance of genetic variation in alcohol dehydrogenase of drosophila.	prior studies showed that differences in alcohol dehydrogenase (adh) activity across genotypes of drosophila are decisive for the outcome of selection by ethanol. in the present paper, the effect on adh activity and egg-to-adult survival of combinations of ethanol, propan-2-ol, and acetone in naturally occurring concentrations is examined. propan-2-ol is converted into acetone by adh in vitro. acetone is considered a competitive inhibitor of ethanol for the adh enzymes. the melanogaster-adh-s al ...	1994	28568248
the genetics of an isolating mechanism between two sibling species of drosophila.	matings between drosophila simulans females and males of the sibling species d. mauritiana are of abnormally short duration. these rapid matings interrupt the transfer of sperm, leading to substantial reproductive isolation in interspecific as compared to intraspecific copulations. genetic analysis of this behavior shows that it is influenced much more by the male than the female genotype, with genes from d. simulans being dominant. in males, shortened copulation is caused by interspecific diver ...	1993	28567909
the effects of interspecific y chromosome replacements on hybrid sterility within the drosophila simulans clade.	we attempted to introgress y chromosomes between three sibling species of drosophila: d. simulans, d. sechellia and d. mauritiana. four d. sechellia y chromosomes were introgressed into d. simulans without loss of fertility whereas the four reciprocal introgressions (d. simulans y introgressed into d sechellia) all result in sterility. both reciprocal y introgressions of d. simulans and d. mauritiana (four of each) also result in sterility. compared with d. simulans males, the males with the d. ...	1993	8244006
genetic control of pheromones in drosophila simulans. ii. kété, a locus on the x chromosome.	the production of drosophila cuticular hydrocarbons, including contact pheromones, is under polygenic control. to investigate x-linked loci, ems mutations were induced in drosophila simulans flies. a mutant strain was discovered which in both sexes show a reduction in the biosynthesis of both 7-tricosene (7-t) the species contact pheromone and all other linear hydrocarbons. the locus controlling this effect, kété, is recessive and was localized to i, 18.5. unlike a previously identified gene on ...	1993	8454203
analysis of drosophila chromosome 4 using pulsed field gel electrophoresis.	previous estimates of the size of drosophila melanogaster chromosome 4 have indicated that it is 1% to 4% of the genome or approximately 6 mb. we have used pulsed field gel electrophoresis (pfge) to separate megabase-sized molecules of d. melanogaster chromosomal dna. southern blots of these gels were probed with dna fragments from the cubitus interruptus and zfh-2 genes, which are located on chromosome 4. they each identify the same-sized distinct band that migrates at approximately 5.2 mb in d ...	1993	8149812
evidence for adaptive evolution of the g6pd gene in the drosophila melanogaster and drosophila simulans lineages.	proponents of the neutral theory argue that evolution at the molecular level largely reflects a process of random genetic drift of neutral mutations. under this theory, levels of interspecific divergence and intraspecific polymorphism are expected to be correlated across classes of nucleotide or amino acid sequences with different degrees of functional constraint, such as synonymous and replacement sites. nucleotide sites with reduced polymorphism should show comparably reduced levels of intersp ...	1993	8356041
noninvolvement of the long terminal repeat of transposable element 17.6 in insecticide resistance in drosophila.	waters and colleagues recently suggested [waters, l. c., zelhof, a. c., shaw, b. j. & ch'ang, l.-y. (1992) proc. natl. acad. sci. usa 89, 4855-4859] that an insertion of a long terminal repeat of transposable element 17.6 into the 3' untranslated region of a p450 gene leads to susceptibility to the insecticide ddt in drosophila melanogaster. we tested this hypothesis by screening lines from around the world and found that the presence or absence of a long terminal repeat was uncorrelated with re ...	1993	8390673
lack of correlation between interspecific divergence and intraspecific polymorphism at the suppressor of forked region in drosophila melanogaster and drosophila simulans.	levels of dna sequence polymorphism at the suppressor of forked [su(f)] region in natural populations of drosophila melanogaster and drosophila simulans are estimated by restriction map analysis. su(f) is located at the base of the euchromatic portion of the x chromosome where the level of crossing-over per physical length is extremely low. in a survey of 55 alleles from three natural populations of d. melanogaster, only 2 restriction sites of 27 hexanucleotide and 108 tetranucleotide restrictio ...	1993	8095333
hybrid lethal systems in the drosophila melanogaster species complex. i. the maternal hybrid rescue (mhr) gene of drosophila simulans.	hybrid females from drosophila simulans females x drosophila melanogaster males die as embryos while hybrid males from the reciprocal cross die as late larvae. the other two classes are sterile adults. letting c, x, and y designate egg cytoplasm, x, and y chromosomes, respectively, and subscripts m and s stand for melanogaster and simulans, cmxmys males are lethal in the larval stage and are rescued by the previously reported genes, lhr (lethal hybrid rescue) in simulans or hmr (hybrid male resc ...	1993	8436276
a single-amino acid substitution in a gamma-aminobutyric acid subtype a receptor locus is associated with cyclodiene insecticide resistance in drosophila populations.	resistance to cyclodiene insecticides, documented in at least 277 species, is perhaps the most common kind of resistance to any pesticide. by using cyclodiene resistance to localize the responsible gene, a gamma-aminobutyric acid type a receptor/chloride ion-channel gene was previously cloned and sequenced from an insecticide-susceptible drosophila melanogaster strain. we now describe the molecular genetics of the resistance allele. a single-base-pair mutation, causing a single-amino acid substi ...	1993	8095336
dna sequence variation at the period locus within and among species of the drosophila melanogaster complex.	a 1.9-kilobase region of the period locus was sequenced in six individuals of drosophila melanogaster and from six individuals of each of three sibling species: drosophila simulans, drosophila sechellia and drosophila mauritiana. extensive genealogical analysis of 174 polymorphic sites reveals a complex history. it appears that d. simulans, as a large population still segregating very old lineages, gave rise to the island species d. mauritiana and d. sechellia. rather than considering these spec ...	1993	8436278
hybrid lethal systems in the drosophila melanogaster species complex. ii. the zygotic hybrid rescue (zhr) gene of d. melanogaster.	hybrid females from drosophila simulans females x drosophila melanogaster males die as embryos while hybrid males from the reciprocal cross die as larvae. we have recovered a mutation in melanogaster that rescues the former hybrid females. it was located on the x chromosome at a position close to the centromere, and it was a zygotically acting gene, in contrast with mhr (maternal hybrid rescue) in simulans that rescues the same hybrids maternally. we named it zhr (zygotic hybrid rescue). the gen ...	1993	8436277
evolution of postmating reproductive isolation: measuring the fitness effects of chromosomal regions containing hybrid male sterility factors.	at least six regions of the x chromosome can cause male sterility when introgressed from drosophila mauritiana into drosophila simulans. in this article, we present the results of the other fitness effects caused by two x-linked regions that contain hybrid male sterility factors. in both regions, females that are heterozygous for an introgression with such a sterility factor produce substantially-fewer offspring than females heterozygous for an introgression that lacks the sterility factor. thus ...	1993	19425976
regulatory aspects of esterase 6 activity variation in sibling drosophila species.	esterase 6 in drosophila melanogaster, drosophila simulans and drosophila mauritiana is produced in several life stages and diverse tissues, but the major pulse of expression is in the sperm ejaculatory duct of adult males. comparison of est6 activity levels among several lines of d. melanogaster, d. simulans and d. mauritiana reveals two major quantitative differences among the species. first, newly eclosed females of both d. simulans and d. mauritiana show significantly higher est6 activity th ...	1993	8360077
genetics of reproductive isolation in the drosophila simulans clade: dna marker-assisted mapping and characterization of a hybrid-male sterility gene, odysseus (ods).	in this study, we address the question of whether there exist major genes that cause complete male sterility in the interspecific hybrids of drosophila and, if they do, how these genes may be characterized at the molecular level. our approach is to introgress small segments of the x chromosome from drosophila mauritiana (or drosophila sechellia) into drosophila simulans by repeated backcrosses for more than 20 generations. the introgressions are monitored by both visible mutations and a series o ...	1993	8514135
the genetic basis of haldane's rule and the nature of asymmetric hybrid male sterility among drosophila simulans, drosophila mauritiana and drosophila sechellia.	haldane's rule (i.e., the preferential hybrid sterility and inviability of heterogametic sex) has been known for 70 years, but its genetic basis, which is crucial to the understanding of the process of species formation, remains unclear. in the present study, we have investigated the genetic basis of hybrid male sterility using drosophila simulans, drosophila mauritiana and drosophila sechellia. an introgression of d. sechellia y chromosome into a fairly homogenous background of d. simulans did ...	1993	8514134
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 ...	1993	7689622
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 ...	1993	8511587
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 ...	1993	8224814