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temperature sensitive events between photoreceptor and circadian clock?the phase shifting action of low temperature pulses of 6 degrees c and 2 h duration administered to the various phases of the drosophila pseudoobscura circadian rhythm and the action of light pulses given 30 min after the beginning of these low temperature pulses have been investigated. the phase response curve obtained from experiments with light pulses during low temperature cannot be explained on the basis of a straightforward and sequential phase shifting of the oscillation by the various tr ...2002125969
frequency-dependent selection at the pgm-1 locus of drosophila pseudoobscura.frequency-dependent fitness was studied at the pgm-1 locus of drosophila pseudoobscura with respect to two fitness components: rate of development and larva-to-adult survival. the pgm-1 locus is very polymorphic with only two alleles, pgm-1(100) and pgm-1(104), occurring at high frequencies. for each of these two alleles, 20 homozygous strains were obtained from a sample of 1,140 wild-inseminated females. first-instar larvae of the two genotypes were combined in a set of eight different frequenc ...1979161241
extent of genetic variation at a highly polymorphic esterase locus in drosophila pseudoobscura.the esterase-5 locus of drosophila pseudoobscura has been screened for variation by using a wide variety of electrophoretic conditions and by testing heat sensitivity. among 50 isogenic lines from 17 populations, 21 genetic variants were found at the locus, 18 by electrophoresis and 3 by heat denaturation. including alleles previously known, there are a total of 30 alleles at this locus in natural populations. this represents a doubling of the previous estimates of polymorphism at this locus. th ...1978283418
evidence for selection by male mating success in natural populations of drosophila pseudoobscura.gene arrangement frequencies were determined at two stages in the life history of drosophila pseudoobscura taken from nature. three populations in the central highlands of mexico were each sampled twice during 1976. gene arrangement frequencies were measured in adult males and in larvae that were the offspring of females collected at the same time. the adult males were in all likelihood a representative sample of those who fathered the larvae produced by the wild females. differences in gene arr ...1979286338
population genetics of drosophila amylase. i. genetic control of tissue-specific expression in d. pseudoobscura.drosophila pseudoobscura is polymorphic for tissue-specific expression of alpha-amylase in adult midguts. this enzyme is encoded by a single locus, amy, on the third chromosome. in this paper we show: (1) up to about 12 days post-eclosion, the midgut activity patterns remain stable; after 12 days areas not showing activity previously begin to show activity. thus, the genes controlling the expression of amy are temporally acting. (2) diet affects the quantitative, but not the qualitative, express ...1979488706
population genetics of drosophila amylase. ii. geographic patterns in d. pseudoobscura.morph frequencies of three related polymorphisms were determined in ten natural populations of drosophila pseudoobscura. they are the well-known inversion polymorphism of the third chromosome and the polymorphism for alpha-amylase produced by the structural gene amy (which resides on the third chromosome). the third polymorphism was for tissue-specific expression of amy in adult midguts; a total of 13 different patterns of activity have been observed. the preceding paper (powell and lichtenfels ...1979488707
inbreeding and mating patterns in drosophila pseudoobscura. 2004539969
genic heterogeneity within electrophoretic "alleles" and the pattern of variation among loci in drosophila pseudoobscura.an investigation, similar to our previously reported xanthine dehydrogenase study, was undertaken to examine the extent of hidden genic variation at nine loci (five larval proteins, three esterases and one aldehyde oxidase) by sequential application of various electrophoretic criteria employing ph, gel concentration and buffer variation. polymorphic loci appear to fall into two distinct groups: weakly polymorphic, including larval protein 6, 7, 8, 10 and 13 and esterase-1 and -6; and highly poly ...1966546677
positive and negative geotaxis: sex-linked traits in drosophila pseudoobscura.using a hirsch classification maze, selection was made for positive and negative geotactic behaviors in three different strains of drosophila pseudoobscura. hybridization studies were then carried out with flies from the diverged strains. the geotactic scores of the parents and f1 flies indicate that both negative and positive geotactic behaviors in these strains are strongly influenced by genes in the x chromosome. additional hybridization studies using flies from strains with similar phenotype ...1978565202
a test for rare male mating advantage at an "enzyme locus" in drosophila.matings between drosophila pseudoobscura strains differing at the amylase (amy) locus were observed in elens-wattiaux chambers. males homozygous for either amy1.00 or amy0.84 alleles in the ch gene arrangement enjoyed a mating advantage when moderately rare, but none when quite rare. the minority male advantage for strains differing at the amy locus, and other loci linked to it, was comparable in size to that observed between strains carrying the st or ch gene arrangements, and either alike or d ...1977603476
study of the charge-state model for electrophoretic variation using isoelectric focusing of esterase-5 from drosophila pseudoobscura. 1978683345
gene frequencies of an isolated population of drosophila pseudoobscura.allozyme and karyotype frequencies were determined for an isolated population of drosophila pseudoobscura on san miguel island off the california coast. this population was not very different from that of the mainland, and seems to indicate that isolation does not necessarily lead to genetic differentiation.2003731008
substrate-specific enzyme variation in natural populations of drosophila pseudoobscura.by using a number of different alcohols as substrates, eight alcohol dehydrogenase loci were discovered in drosophila pseudoobscura. each of these loci can take more than one substrate. several of these loci differed in their tissue specificities and activity patterns during development. the genic variation in natural populations was studied at four of these loci and three of them were polymorphic. a quantitative study of substrate-specific differences among alleles of the same locus produced ne ...1976773744
protein synthesis inhibition alters drosophila mating behavior.fruit fly drosophila pseudoobscura virgin ar females mate preferentially with ar males given a choice between ar and or males. however, ar females which mated with or males when young show a significant change in sexual selection in favor of or over ar males in subsequent simultaneous choice tests. ingestion of food moistened with 4 ml cycloheximide (400 microng/ml) produces 75% protein synthesis inhibition in the female flies. females exposed to cycloheximide (cxm) immediately after their initi ...1977857258
a comparative study of the esterase-5 locus in drosophila pseudoobscura, d. persimilis and d. miranda.electrophoretic phenotypes of the esterase-5 locus were examined in the sibling species d. pseudoobscura, d. persimilis and d. miranda. d. persimilis alleles were found to have uniformly higher charge on monomers than corresponding alleles of either d. pseudoobscura or d. miranda. consequently, d. persimilis shares no alleles in common with either d. pseudoobscura or d. miranda, while the latter two species share a number of alleles. it was discovered that by increasing the concentration of acry ...1977863241
further studies on gene polymorphism in the mainbody and geographically isolated populations of drosophila pseudoobscura.we have examined polymorphism at 22 additional loci in the populations from the mainbody of drosophila pseudoobscura and an isolated population from bogotá, columbia, which also shows partial reproductive isolation from mainbody populations. these studies extend our previous observations of reduced gene polymorphism and apparent lack of unique allele in the bogotá population.1977863242
chromosomal and allozymic diagnosis of three species of drosophila. drosophila pseudoobscura, d. persimilis, and d. miranda.techniques are presented for distinguishing the sibling species d. pseudoobscura, d. persimilis, and d. miranda in two ways: by differences in the banding sequence of salivary chromosomes, and by the frequencies of allozymes at certain diagnostic loci.2009874309
hyperactivity and faster replicating property of the two arms of the male x of drosophila pseudoobscura.the two arms of the x chromosome of drosophila pseudoobscura have different phylogenetic origin, the xl being homologous to the x and the xr homologous to the 3l of d. melanogaster. the replicative and transcriptive activities of the two arms have been examined in order to understand how such phylogenetically different components of the x contribute toward the chromosomal basis of dosage compensation. the 3h-uridine labelled autoradiograms of the polytene chromosomes of larval salivary glands re ...1976946831
recongition and sexual selection in drosophila: classification, quantification, and identification.drosophila pseudoobscura females show a positive bias toward mating with males whose proportion in the population is low. they can perform this discrimination even when three strains of males are present. the olfactory recognition required for this discrimination entails a hierarchically ordered recognition system and a natural unit of olfactory strength.1976948745
homeostatic drive counteracting selection for positive and negative phototaxis and geotaxis in drosophila pseudoobscura.tested in hirsch-hadler mazes, drosophila pseudoobscura is on the average geoneutral and photoneutral. strongly geo- and photopositive and geo- and photonegative populations can be obtained by artificial selection, but upon relaxation of the selection they tend to relapse toward neutrality. this genetic homeostasis is due to natural selection favoring neutrality. experiments are described in which artificial selection for positivity and for negativity was deliberately made so weak that it only c ...1976973830
genetic heterogeneity within electrophoretic "alleles" of xanthine dehydrogenase in drosophila pseudoobscura.an experimental plan for an exhaustive determination of genic variation at structural gene loci is presented. in the initial steps of this program, 146 isochromosomal lines from 12 geographic populations of d. pseudoobscura were examined for allelic variation of xanthine dehydrogenase by the serial use of 4 different electrophoretic conditions and a head stability test. the 5 criteria revealed a total of 37 allelic classes out of the 146 genomes examined where only 6 had been previously revealed ...19761001881
the frequency and allelism of lethal chromosomes in isolated desert populations of drosophila pseudoobscura.second-chromosome lethals were extracted from four populations of drosophila pseudoobscura in southern california. two of the populations were from desert oases and two from the classic habitat on mt. san jacinto, previously studied by dobzhansky. allelism tests were made on the lethals within and between all locations. the frequency of lethal second-chromosomes in each location was 0.18, and this was not different from the results of other workers for samples throughout the species range. inter ...19761010313
a biometrical analysis of a mating characteristic in drosophilia.a model is described for the biometrical analysis of interaction behavioural characteristics. the model is illustrated by analysis of the mating speed of drosophila pseudoobscura derived from crosses of fast and of slow mating strains generated through artificial selection.19751054670
allelic heterogeneity within allozymes separated by electrophoresis in drosophila pseudoobscura.electrophoretic separation of esterase-5 allozymes of drosophila pseudoobscura in gels of different acrylamide concentrations and in different buffer systems has revealed the existence of six different alleles within the most frequent class, esterase-5(1.00), and three alleles in the other most frequent class, esterase-5(1.07). two of the alleles affect subunit binding. esterase-5 allozyme classes based on electrophoresis in 5% acrylamide gels are therefore highly heterogeneous.19761069304
fitness of karyotypes in drosophila pseudoobscura.in the dynamics of the survival of chromosomal polymorphism selection may be operating at the genic level, at the chromosomal level or at the supergene level. tests designed to distinguish between these levels were run on drosophila pseudoobscura. there was no evidence for heterosis, a necessary requirement for gene-determined chromosomal polymorphism a strong chromosmal selection was observed. no evidence was found for the presence within one locality of more than a single superallele for each ...19751126618
further evidence for selective differences between isoalleles in drosophila.a number of separate strains of drosophila pseudoobscura were inbred for 38 generations of brother-sister mating with forced heterozygosity for two alleles of either the octanol dehydrogenase or esterase-5 locus. crosses were set up within each of these inbred lines such that simple mendelian ratios were expected, and eggs from these crosses were placed on media with additions simple chemicals likely to interact with alleles of the two loci--octanol and ethanol for the odh locus and tributyrin a ...19751126619
fitness of allozyme variants in drosophila pseudoobscura. i. selection at the pgm-1 and me-2 loci.we have studied in drosophila pseudoobscura the effect of allozyme variation on seven fitness components: female fecundity, egg hatchability, egg-to-adult survival under near-optimal and under competitive conditions, rate of development under near-optimal and under competitive conditions, and mating capacity of males. three genotypes at each of two loci, pgm-1 and me-2, have been studied in various combinations. these two loci are highly polymorphic in natural populations of d. pseudoobscura. st ...19751126623
photobehavioral differentiation in natural populations of drosophila pseudoobscura and drosophila persimilis.the photoresponses of natural populations of d. pseudoobscura and d. persimilis, occurring sympatrically, are measured in two environmental conditions ("at rest" and "disturbed"). comparisons of the responses, intraspecifically and interspecifically, lead to the following conclusions. these must be considered within the confines of the operational nature of the measurement of laboratory photoresponses. (1) within each species population, significant nonenvironmental differentiation has been allo ...19751131147
population genetics of mexican drosophila. i. chromosomal variation in natural populations of drosophila pseudoobscura from central mexico.drosophila pseudoobscura populations of central mexico are chromosomally highly polymorphic. five gene arangements in the third chromosome are endemic, including the two newly described in the present article. the phylogenetic tree of the gene arrangements known in the species is shown in figure 1. the ones found in central mexico all belong to the santa cruz "phylad", while in the northern part of the species area both santa cruz and standard phylads are widespread. some inferences concerning t ...19751165399
chromosomal basis of dosage compensation in drosophila viii. faster replication and hyperactivity of both arms of the x-chromosome in males of drosophila pseudoobscura and their possible significance.3h-thymidine and 3h-uridine labeling patterns of the x-chromosome arms of drosophila pseudoobscura have been examined autoradiographically. results show that in all phases of replication, namely, initial, middle and terminal, both arms of the x-chromosome in the male are advanced by one or two steps of 3h-thymidine labeling in comparison with the autosomes, and both arms in the female show more or less similar labeling profile as the autosomes. both the arms in the male show pale stainability an ...19751201689
distribution among the chromosomes of drosophila pseudoobscura of the genes governing the response to light.most strains of drosophila pseudoobscura are neutral to light when tested in phototactic mazes. however, clear-cut photopositive and photogenative populations are obtained by selection over a series of generations. the genetic nature of the differences between the positive and negative populations has been studied in crosses in which the three large autosomes carried mutant markers. all chromosomes contain genes which influence the response to light. the third chromosome has the strongest effect ...19751205129
dna replication in polytene chromosomes of drosophila pseudoobscura: new facts & their implications. 19751218903
interchromosomal asynchrony of dna replication in polytene chromosomes of drosophila pseudoobscura.analysis of 3h-thymidine autoradiograms of late third instar larval salivary glands of drosophila pseudoobscura revealed a unique example of asynchrony of replication in the autosome complement. the two autosomal arms, 2 and 3, show similar labeling pattern during the initial phases, dd to 3c, and thereafter, the chromosome 3 has fewer labeled sites than chromosome 2 until the most terminal pattern, 1d. detailed sitewise analysis of 3h-thymidine labeling shows that while nearly 54% of the sites ...19761248337
polymorphism for dimerizing ability at the esterase-5 locus in drosophila pseudoobscura.three new alleles are reported at the esterase-5 locus of drosophila pseudoobscura. all three of these alleles are different from those previously reported in their ability to dimerize. one allele will not form heterodimers or homodimers and exists only as a monomer. a second allele does form heterodimers but will not form homodimers. the third allele forms both hetero- and homodimers as well as forming monomers. estimates of the frequency of these alleles in a natural population are given. the ...19761248736
genetics of natural populations, xliii. further studies on rates of dispersal of drosophila pseudoobscura and its relatives.the amount of gene flow among local populations of a species is determined by the dispersal capacity of that species. population samples of drosophila pseudoobscura, d. persimilis, d. azteca, and d. miranda were collected, marked with ultraviolet fluorescent dusts, and released as soon as possible after capture. one and two days after release, recaptures were made on baits placed at 40-meter intervals in straight lines intersecting the release point. on alternative days, the baits were placed in ...19761269906
molecular population genetics of an electrophoretically monomorphic protein in the alcohol dehydrogenase region of drosophila pseudoobscura.nucleotide sequence data from the alcohol dehydrogenase (adh) region of 18 isochromosomal strains of drosophila pseudoobscura were used to determine whether the lack of amino acid polymorphism in adh results from a low neutral mutation rate or a recent directional selection event. we estimated the neutral mutation parameter, 4nmu, in synonymous sites for 17 subregions of adh. the nucleotide diversity data were tested for departures from an equilibrium neutral model with two statistical tests. th ...19921398051
variable rates of evolution among drosophila opsin genes.dna sequences and chromosomal locations of four drosophila pseudoobscura opsin genes were compared with those from drosophila melanogaster, to determine factors that influence the evolution of multigene families. although the opsin proteins perform the same primary functions, the comparisons reveal a wide range of evolutionary rates. amino acid identities for the opsins range from 90% for rh2 to more than 95% for rh1 and rh4. variation in the rate of synonymous site substitution is especially st ...20051398053
estimates of gene flow in drosophila pseudoobscura determined from nucleotide sequence analysis of the alcohol dehydrogenase region.the genetic structure of drosophila pseudoobscura populations was inferred from a nucleotide sequence analysis of a 3.4-kb segment of the alcohol dehydrogenase (adh) region. a total of 99 isochromosomal strains collected from 13 populations in north and south america were used to determine if any population departed from a neutral model and to estimate levels of gene flow between populations. this study also included the nucleotide sequences from two sibling species, d. persimilis and d. miranda ...19921427038
nucleotide polymorphism at the xanthine dehydrogenase locus in drosophila pseudoobscura.sequential polyacrylamide electrophoresis has revealed 20 allozymes of xanthine dehydrogenase (xdh) in drosophila pseudoobscura. dna sequence determination of seven isolates of the xdh locus that represent six allozyme classes are presented here. of the 5,456 sites examined, 180 are polymorphic, with 27 polymorphisms occurring at nonsynonymous, or replacement, sites. an average of nine amino acids differ between xdh allozyme classes, with 85% of the polymorphic amino acids singly represented. th ...19921552841
the urate oxidase gene of drosophila pseudoobscura and drosophila melanogaster: evolutionary changes of sequence and regulation.the urate oxidase (uo) transcription unit of drosophila pseudoobscura was cloned, sequenced, and compared to the uo transcription unit from drosophila melanogaster. in both species the uo coding region is divided into two exons of approximately equal size. the deduced d. pseudoobscura and d. melanogaster uo peptides have 346 and 352 amino acid residues, respectively. the nucleotide sequences of the d. pseudoobscura and d. melanogaster uo protein-coding regions are 82.2% identical whereas the ded ...19921556745
sex chromosome loss induced by the "sex-ratio" trait in drosophila pseudoobscura males.frequencies of sex chromosome aneuploid sperm were measured for standard and "sex-ratio" drosophila pseudoobscura males with identical genetic backgrounds. the "sex-ratio" males produced a 15.6-fold higher frequency of nullo-xy sperm than the standard males produced, but diplo-xy sperm were produced at the same rate in the two types of males. "sex-ratio" males with the same sr chromosome but with different chromosome backgrounds were found to produce different frequencies of sterile sons. these ...20031578108
an evolutionary model for the duplication and divergence of esterase genes in drosophila.the esterase 5 (est-5 = gene, est 5 = protein) enzyme in drosophila pseudoobscura is encoded by one of three paralogous genes, est-5a, est-5b, and est-5c, that are tightly clustered on the right arm of the x chromosome. the homologous est-6 locus in drosophila melanogaster has only one paralogous neighbor, est-p. comparisons of coding and flanking dna sequences among the three d. pseudoobscura and two d. melanogaster genes suggest that two paralogous genes were present before the divergence of d ...19921593643
the effects of anthranilic acid on gene expression.1. a drosophila pseudoobscura amylase gene cloned in escherichia coli is expressed at high levels. the expression of this gene is repressed when glucose (0.5% final concentration) is added to a starch minimal medium culture of e. coli cells containing the amylase plasmid. 2. addition of anthranilic acid (5 and 7 mm final exogenous concentration) to catabolite repressed cells mimics the action of adenosine 3'5' cyclic monophosphate (camp) by depressing the expression of the amylase. 3. the result ...19901691993
dna sequence evolution of the amylase multigene family in drosophila pseudoobscura.the alpha-amylase locus in drosophila pseudoobscura is a multigene family of one, two or three copies on the third chromosome. the nucleotide sequences of the three amylase genes from a single chromosome of d. pseudoobscura are presented. the three amylase genes differ at about 0.5% of their nucleotides. each gene has a putative intron of 71 (amy1) or 81 (amy2 and amy3) bp. in contrast, drosophila melanogaster amylase genes do not have an intron. the functional amy1 gene of d. pseudoobscura diff ...19901699840
amylase gene expression in intraspecific and interspecific somatic transformants of drosophila.the amylase locus in drosophila melanogaster normally contains two copies of the structural gene for alpha-amylase, a centromere-proximal copy, amy-p, and a distal copy, amy-d. products of the two genes may display discrete electrophoretic mobilities, but many strains known to carry the amy duplication are characterized by a single amylase electromorph, e.g., oregon-r, which produces the mobility variant amy-1. a transient expression assay was used in somatic transformation experiments to test t ...19901699842
molecular analysis of evolutionary changes in the expression of drosophila esterases.drosophila melanogaster transformed with the esterase 5 (est-5) gene from drosophila pseudoobscura were used to assess the evolutionary basis for differences in the sex- and tissue-specific expression of the esterase 5 (est 5) enzyme in d. pseudoobscura relative to its homologue in d. melanogaster, est 6. est 5 is expressed in the eyes and hemolymph of transformed d. melanogaster just as it is in d. pseudoobscura, but it is not detectable in the ejaculatory duct, where the homologous enzyme, est ...19901700427
molecular evolution of inversions in drosophila pseudoobscura: the amylase gene region.the amylase region of the third chromosome of drosophila pseudoobscura has been cloned and localized to cytological band 73a. it is contained within a series of highly polymorphic inversions and serves as a convenient tool for a molecular evolutionary analysis of the inverted gene arrangements. amylase in d. pseudoobscura is a family of three genes, and some chromosomes have deletions for one or two of them. two overlapping clones covering 26 kilobases were isolated and used as probes to survey ...19911702542
coadaptation revisited.during the four decades or more since dobzhansky introduced the term "coadaptation" to refer to the commonly observed selective superiority of inversion heterozygotes in populations of drosophila pseudoobscura, the definition of the term has evolved, as have views concerning the rapidity with which coadaptation might occur. indeed, the paucity of demonstrated instances of linkage disequilibrium in natural populations has led many to dismiss coadaptation as a factor in evolutionary change. the pr ...20101901579
length polymorphism in the threonine-glycine-encoding repeat region of the period gene in drosophila.single-fly polymerase chain reaction amplification and direct dna sequencing revealed high levels of length polymorphism in the threonine-glycine encoding repeat region of the period (per) gene in natural populations of drosophila melanogaster. dna comparison of two alleles of identical lengths gave a high number of synonymous substitutions suggesting an ancient time of separation. however detailed examination of the sequences of different thr-gly length variants indicated that this divergence c ...19911904500
dosage compensation of the drosophila pseudoobscura hsp82 gene and the drosophila melanogaster adh gene at ectopic sites in d. melanogaster.measurements were made of the amounts of larval rna transcribed from the autosomal adh gene of drosophila melanogaster and the x chromosomal hsp82 gene of drosophila pseudoobscura carried on the same p-element transposon inserted at various sites in the d. melanogaster genome. both genes were fully compensated at sites in euchromatic regions of the x chromosome but neither was compensated at a site in the centric beta-heterochromatin of the x chromosome. no compensation of the d. pseudoobscura h ...19911907376
the adh genomic region of drosophila ambigua: evolutionary trends in different species.the study of individual genes is essential to a comprehensive understanding of genome evolution. the wealth of information on alcohol dehydrogenase (adh) in drosophila makes this gene particularly suitable for such analysis. we have characterized more than 4 kb of the genomic adh region in drosophila ambigua and compared this region to drosophila mauritiana and drosophila pseudoobscura. the presence of two genes, adh and 3'orf (open reading frame), has been confirmed and some of their essential ...19911908016
perturbation-reperturbation test of selection vs. hitchhiking of the two major alleles of esterase-5 in drosophila pseudoobscura.a perturbation-reperturbation tests selective neutrality of 100/100/100/100/100 and 106/100/100/100/100, the two most common alleles at the highly polymorphic x-linked locus esterase-5 in drosophila pseudoobscura. a total of 22 replicate populations are set up in cages, 11 start at a high frequency of 76% (u) and 11 at a low frequency of 21% (n) of the 106 allele. allele frequencies change directionally and decrease in both u and n populations as groups and reach equilibria of 60 and 14%, respec ...19911936955
four decades of inversion polymorphism in drosophila pseudoobscura.we report data that continue the studies of dobzhansky and others on the frequencies of third-chromosome inversions in natural populations of drosophila pseudoobscura in north america. the common gene arrangements continue to be present in frequencies similar to those described four decades ago, and the broad geographic patterns also remain unchanged. there is only one pronounced trend over time: the increase in frequency of the tree line inversion in pacific coast populations.19911946458
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
molecular analysis of the bicoid gene from drosophila pseudoobscura: identification of conserved domains within coding and noncoding regions of the bicoid mrna.the specification of anterior positional information during drosophila embryogenesis is largely dependent upon the function of the maternal-effect gene bicoid (bcd). two aspects of bcd function are particularly striking. first, the bcd protein product forms a gradient during early embryogenesis, which regulates the transcription of at least one zygotic segmentation gene, hunchback, in a concentration dependent manner. secondly, formation of the bcd protein gradient is dependent upon the specific ...19901975239
male-sex-ratio trait in drosophila pseudoobscura: frequency of autosomal aneuploid sperm.males with the sr x chromosome show the "sex-ratio" (sr) phenotype in which they produce almost entirely daughters. the few sons (about 1%) are invariably sterile x/o males and result entirely from nullo-xy sperm. the "male-sex-ratio" (msr) phenotype is a modified form of sr in which sr/y males produce a higher frequency of sterile x/o sons. the msr trait is due to the presence of the sr x-chromosome in males which are also homozygous for one or more autosomes from the l116 strain. here the freq ...19912004709
interspecific comparisons of the structure and regulation of the drosophila ecdysone-inducible gene e74.the drosophila melanogaster e74 gene is induced directly by the steroid hormone ecdysone and is a member of a small set of "early" genes that appear to trigger the onset of metamorphosis. the gene consists of three overlapping transcription units encoding two proteins, e74a and e74b, which possess a common c terminus. according to the ashburner model for ecdysone's action, an e74 protein product potentially functions as a transcriptional activator of "late" genes as well as a repressor of early ...19912016053
species differences in the temporal pattern of drosophila urate oxidase gene expression are attributed to trans-acting regulatory changes.the drosophila melanogaster urate oxidase (uo)-encoding gene is expressed in the third-instar larva and adult. in contrast, the drosophila pseudoobscura uo gene is only expressed in the adult, whereas the drosophila virilis uo gene is expressed only in the third-instar larva. uo activity in these three drosophila species is detected exclusively within the malpighian tubules. by using p-element mediated germ-line transformation, uo genes from d. pseudoobscura and d. virilis were integrated into t ...19912062830
nucleotide sequence analysis of adh genes estimates the time of geographic isolation of the bogota population of drosophila pseudoobscura.the population of drosophila pseudoobscura at bogota, columbia, is geographically and partially reproductively isolated from populations in the main body of the species in north america. the degree of genetic differentiation and time of divergence between populations at bogota and apple hill, ca, were estimated by comparison of 3388 nucleotides in the alcohol dehydrogenase region (adh and adh-dup genes) of 18 strains. of the 146 polymorphic nucleotide sites detected, 68 and 31 were unique to the ...19912068088
conservatism of sites of trna loci among the linkage groups of several drosophila species.the sites of seven trna genes (arg-2, lys-2, ser-2b, ser-7, thr-3, thr-4, val-3b) were studied by in situ hybridization. 125i-labeled trna probes from drosophila melanogaster were hybridized to spreads of polytene chromosomes prepared from four drosophila species representing different evolutionary lineages (d. melanogaster, drosophila hydei, drosophila pseudoobscura, and drosophila virilis). most trna loci occurred on homologous chromosomal elements of all four species. in some cases the number ...19902107332
mitochondrial dna evolution in the obscura species subgroup of drosophila.mitochondrial dna (mtdna) restriction site maps for nine species of the drosophila obscura subgroup and for drosophila melanogaster were established. taking into account all restriction enzymes (12) and strains (45) analyzed, a total of 105 different sites were detected, which corresponds to a sample of 3.49% of the mtdna genome. based on nucleotide divergences, two phylogenetic trees were constructed assuming either constant or variable rates of evolution. both methods led to the same relations ...19902120450
p-transposable vectors expressing a constitutive and thermoinducible hsp82-neo fusion gene for drosophila germline transformation and tissue-culture transfection.three p-transposable vectors (approx. 16, 12, and 9 kb) were constructed containing a hsp82-neo fusion gene encoding a truncated heat-shock protein 82 of drosophila pseudoobscura and the bacterial neomycin phosphotransferase (npt). in transgenic drosophila melanogaster, hsp82-neo exhibits high levels of housekeeping gene promoter and npt activities in all cells in the absence of heat-shock and is further induced (fivefold) by elevated temperatures (35 degrees-36 degrees c). the hsp82-neo selecti ...19902165019
cloning of the esterase-5 locus from drosophila pseudoobscura and comparison with its homologue in d. melanogaster.a clone of the esterase-5 (est-5) gene from drosophila pseudoobscura has been isolated by hybridization to the cloned est-6 gene of d. melanogaster. southern analysis and sequencing of the cloned dna revealed three regions of similarity to est-6 that have been tentatively identified as genes, est-5a, est-5b, and est-5c. introduction of each of the three genes separately into d. melanogaster by p-element transformation has demonstrated that est-5b encodes an enzyme with the same physical properti ...19902178209
developmental isolation and subsequent adult behavior of drosophila pseudoobscura.when isolated from all contact with other flies until the opportunity to exercise mating choices, drosophila pseudoobscura displays genetically-mediated compensatory behavior: heterokaryotypic females are more vulnerable than homokaryotes to wholly restricted contact with conspecifics. they are less able to demonstrate normal frequency-dependent sexual selection after isolation than their own homokaryotypes. however, the later the isolation in this holometabolous insect--eggs, first instars, sec ...19902288548
synthesis of an attached autosome, c(3)rm, in drosophila pseudoobscura.drosophila pseudoobscura has three acrocentric autosomes. in the experiments reported, homologous arms of the third chromosome were attached to the same centromere. this is a 'reversed metacentric compound' third chromosome, denoted by c(3)rm. this compound chromosome is relatively fertile in within-strain crosses (ca. 50% egg hatch) but sterile when outcrossed to a normal karyotype. when constructing translocations for this experiment, the behavior of the y-autosome translocations suggested tha ...20082323568
an amylase gene from drosophila pseudoobscura is expressed in escherichia coli. functional selection and biochemical comparisons of the fly- and clone-produced amylases.an amylase gene from drosophila pseudoobscura was isolated from a genomic library constructed in pbr322 and cloned in escherichia coli by selecting for the ability of its product to hydrolyze starch, a carbon source not normally utilized by e. coli. hybridization of pamy17f to d. pseudoobscura polytene chromosomes shows a positive signal at the amylase pseudogene locus (bank 78, chromosome 3). the chimeric plasmid pamy17f, has been altered in such a way as to increase amylase expression. souther ...19872443177
nucleotide sequence of the xdh region in drosophila pseudoobscura and an analysis of the evolution of synonymous codons.the nucleotide sequence of the xdh region of drosophila pseudoobscura is presented. the xdh gene structure and organization are compared with the homologous region in d. melanogaster. this locus is shown to have similar organization in the two species, although an additional intron and three insertion/deletion events are described for the d. pseudoobscura coding region. the encoded proteins are predicted to have very similar charges and hydrophobic/hydrophilic domains even though 11% of the amin ...19892493563
distinguishing the forces controlling genetic variation at the xdh locus in drosophila pseudoobscura.fifty-eight isochromosomal lines sampled from two natural populations of drosophila pseudoobscura in california and one from bogota, colombia, were examined using four-cutter restriction mapping. a 4.6-kb region of the xanthine dehydrogenase locus was probed and 66 of 135 restriction sites scored were polymorphic. this predicts that on average every 12th bp would be polymorphic in this region for the genes surveyed if polymorphism occurred randomly along the coding region. in addition, there wer ...20082583480
selection in natural and experimental populations of drosophila pseudoobscura.the inverted gene arrangements of drosophila pseudoobscura were used by th. dobzhansky in pioneering analyses of natural selection. recent experiments have shed light on the mechanisms of selection contributing to the balanced polymorphism for the gene arrangements. in experimental populations, both major components of fitness, viability and fertility, are frequency dependent, and rare genotypes often have a selective advantage. viabilities are also density dependent. the frequency dependence an ...19892687095
localization of genes causing postzygotic isolation in two hybridizations involving drosophila pseudoobscura.the genes causing postzygotic isolation in two drosophila hybridizations were localized to regions of the x chromosome. the x has a large effect on d. pseudoobscura pseudoobscura ("u.s.a.")-d. pseudoobscura bogotana ("bogota") hybrid male sterility. recombination analysis shows that this effect is due entirely to a small chromosome region representing less than 20 per cent of the x. this result suggests that a single x-linked gene may be involved. a maximum likelihood mapping procedure places th ...19892807977
restriction-map variation in the alcohol dehydrogenase region of drosophila pseudoobscura.a 32-kb region including the adh structural gene was analyzed with six restriction endonucleases in 20 lines of drosophila pseudoobscura, one line of d. persimilis, and one line of d. miranda. nineteen lines of d. pseudoobscura from a single population were estimated to be polymorphic at one in every 15 nucleotides (p = 0.066). any two homologous chromosomes chosen at random were heterozygous at one in 48 (h = 0.021) nucleotides. two small insertions of 50 and 200 bp were found approximately 7 k ...19872833670
historical effective size and the level of genetic diversity in drosophila melanogaster and drosophila pseudoobscura.we report the results of a sequential gel electrophoretic study of protein variation in drosophila melanogaster and its comparison with d. pseudoobscura. the number of alleles and mean heterozygosity were lower in d. melanogaster than in d. pseudoobscura. on the other hand, geographical populations of drosophila melanogaster have been shown to be much more differentiated than those of d. pseudoobscura. the results suggest that in d. melanogaster low-frequency alleles have been lost during the co ...19873107543
conserved arrangement of nested genes at the drosophila gart locus.the drosophila melanogaster gart gene encodes three enzymatic activities in the pathway for purine de novo synthesis. alternative processing of the primary transcript leads to the synthesis of two overlapping polypeptides. the coding sequence for both polypeptides is interrupted by an intron that contains a functional cuticle protein gene encoded on the opposite dna strand. here we show that this nested organization also exists at the homologous locus of a distantly related species, drosophila p ...19873123310
evidence for non-neutrality of mitochondrial dna haplotypes in drosophila pseudoobscura.mitochondrial dna (mtdna) haplotypes usually are assumed to be neutral, unselected markers of evolving female lineages. this assumption was tested by monitoring haplotype frequencies in 12 experimental populations of drosophila pseudoobscura which were polymorphic for mtdna haplotypes. populations were maintained for at least 10 generations, and in one case for 32 generations, while tests of mtdna selective neutrality were conducted. in an initial population, formed from a mixture of two strains ...19883197957
rare male mating advantage in a natural population of drosophila pseudoobscura.the natural selection acting on chromosomal inversions was studied in a natural population of drosophila pseudoobscura. females from this population were allowed to produce offspring from their matings in nature. they were then remated to males from a laboratory strain and again allowed to produce offspring. offspring were also produced from matings of males from nature to laboratory females. diagnosis of salivary chromosomes in these several sets of larval offspring allowed us to deduce the kar ...19883200863
interspecific comparison of the period gene of drosophila reveals large blocks of non-conserved coding dna.we have cloned and sequenced the coding region of the period (per) gene from drosophila pseudoobscura and d. virilis. a comparison with that of d. melanogaster reveals that the conceptual translation products consist of interspersed blocks of conserved and non-conserved amino acid sequence. the non-conserved portion, comprising approximately 33% of the protein sequence, includes the perfect thr-gly repeat of d. melanogaster, which is absent from the d. pseudoobscura and d. virilis proteins. base ...19883208754
cytogenetic mapping of marker genes on the chromosome elements c and e of drosophila pseudoobscura and d. subobscura.enzyme loci, visible marker genes and lambda-cloned dna-sequences from a d. miranda library were mapped cytologically on the chromosome elements c and e of d. pseudoobscura and d. subobscura. new data are incorporated into the linkage maps of the two species. homologous segments can now be localized in the polytene chromosomes with these markers. a comparison of the chromosome elements e of d. melanogaster and d. subobscura shows 12 conserved subsections which have been rearranged by paracentric ...20123504805
genetic divergence under uniform selection. iii. selection for knockdown resistance to ethanol in drosophila pseudoobscura populations and their replicate lines.replicate d. pseudoobscura lines from populations collected at different geographic locations were selected for increased knockdown resistance to ethanol. population background affected the initial rate of response but not the extent that lines responded. lines were tested for physiological traits contributing to increased knockdown resistance. populations showed different correlated responses for two traits (tolerance of ethanol, and of acetone), suggesting that they had responded to selection ...19873597126
macromolecular interaction and the electrophoretic mobility of esterase-5 from drosophila pseudoobscura.esterase-5 is one of the most polymorphic loci in drosophila pseudoobscura. some variants reportedly produce a dimeric enzyme, while a few produce a monomeric form. this paper reports the finding that during electrophoresis esterase-5 exists in a dynamic equilibrium between monomers and dimers, an equilibrium that is dependent on the running temperature of the gels. this is shown by a series of analytical electrophoresis experiments in which the apparent molecular weights of several variants are ...20133606564
genetics of male and female sterility in hybrids of drosophila pseudoobscura and d. persimilis.the genetic basis of male and female sterility in hybrids of drosophila pseudoobscura-drosophila persimilis was studied using backcross analysis. previous studies indirectly assessed male fertility by measuring testis size; these studies concluded that male sterility results from an x chromosome-autosome imbalance. by directly scoring for the production of motile sperm, male sterility is shown to be largely due to an incompatibility between genes on the x and y chromosomes of these two species. ...20133623079
nucleotide sequence of the adh gene region of drosophila pseudoobscura: evolutionary change and evidence for an ancient gene duplication.the alcohol dehydrogenase (adh) locus (adh; alcohol: nad+ oxidoreductase, ec 1.1.1.1) of drosophila pseudoobscura was cloned and sequenced. forty-five percent of the "effectively silent sites" have changed between adh in d. pseudoobscura of the obscura species group and the homologous dna sequence in d. mauritiana, the latter representing the melanogaster species group. the untranslated leader sequence of the adult transcript of d. pseudoobscura has two deletions relative to the d. mauritiana me ...20133666441
habitat choice by drosophila pseudoobscura: the roles of genotype and of experience. 19863718416
laboratory-induced changes in the mate recognition system of drosophila pseudoobscura. 19863718418
desiccation resistance in two species of drosophila.three populations of drosophila pseudoobscura, each one represented by 12 isofemale lines, and one laboratory strain of d. melanogaster were tested for desiccation resistance at two time periods. except in the case of one population of d. pseudoobscura, the ability to withstand drying was significantly greater in females than in the corresponding males. the males of the three populations of d. pseudoobscura differed significantly among themselves in their resistance to desiccation, as did the fe ...20073772067
nearly identical allelic distributions of xanthine dehydrogenase in two populations of drosophila pseudoobscura.in a previous study, keith (1983) showed by sequential gel electrophoresis of the esterase-5 protein in drosophila pseudoobscura that a highly polymorphic locus with many alleles can have very similar frequency distributions in populations separated by 500 km. the present work studies another highly polymorphic locus, xanthine dehydrogenase, in the same california population samples, using the same technique to distinguish allelic classes. twelve electromorphs were found in one population and 15 ...19853871004
mitochondrial dna variation in drosophila pseudoobscura and related species in pacific northwest populations.we have analysed mitochondrial dna (mtdna) from pacific northwest populations of drosophila pseudoobscura, d. persimilis, and d. miranda using six restriction enzymes. we find that hpaii restriction sites are hypervariable compared to the other enzymes used. this hypervariability allows construction of a maximum parsimony map linking each mtdna genotype. small insertions, possibly tandem duplications, appear to have arisen concomitantly with, or subsequent to, speciation events, perhaps within t ...19853880378
chromosomal and behavioral studies of mexican drosophila. iii. inversion polymorphism of d. pseudoobscura.four new gene arrangements of chromosome 3 of drosophila pseudoobscura are reported, as well as an updated phylogenetic sequence of the inversion polymorphism in this species. evidence that the tree line gene arrangement of chromosome 3 was the original form in d. pseudoobscura, and that central mexico is the center of distribution of this species is discussed.19854031462
natural selection vs. random drift: evidence from temporal variation in allele frequencies in nature.we have obtained monthly samples of two species, drosophila pseudoobscura and drosophila persimilis, in a natural population from napa county, california. in each species, about 300 genes have been assayed by electrophoresis for each of seven enzyme loci in each monthly sample from march 1972 to june 1975. using statistical methods developed for the purpose, we have examined whether the allele frequencies at different loci vary in a correlated fashion. the methods used do not detect natural sele ...19854054608
rates of dispersal of drosophila pseudoobscura and its relatives. 19744154451
early and late subjective night phases of the drosophila pseudoobscura circadian rhythm require different energies of blue light for phase shifting. 20094273696
developmental studies in drosophila. ii. ultrastructural analysis of the salivary glands of drosophila pseudoobscura during some stages of development. 19724335117
developmental studies in drosophila. vi. ultrastructural analysis of the salivary glands of drosophila pseudoobscura during the late larval period. 19724340674
genetic analysis of hybrid sterility within the species drosophila pseudoobscura. 19744413557
light dependence in matings of drosophila pseudoobscura. 19744414479
gene differences between the sex ratio and standard gene arrangements of the x chromosome and linkage disequilibrium between loci in the standard gene drosophila pseudoobscura.the standard and sex ratio gene arrangements of the x chromosome of d. pseudobscura differ from each other in allele frequencies at the four x chromosome loci, esterase-5, adult acid phosphatase-6, phosphoglucomutase-1 and octanol dehydrogenase-3. the standard arrangement which is the common arrangement in all populations is polymorphic at these loci in varying degrees, the geographically less widespread sex ratio arrangement has little polymorphism and is genically predominantly e-5(1.04) ap-6( ...19744417060
selection by fertility in drosophila pseudoobscura.fertility, the component of selection due to female fecundity and male mating success, differed significantly among the st/st, st/ar, and ar/ar karyotypes in experimental populations and varied with karyotypic frequency. in relation to st/ar, st/st females and males had higher fertilities at low frequency; ar/ar males and females were at a significant fertility disadvantage at intermediate frequency, while at low and at high frequencies their fertilities matched or exceeded that of the heterokar ...19744426507
fitness of allozyme variants in drosophila pseudoobscura. ii. selection at the est-5, odh and mdh-2 loci. 19744452479
esterases of drosophila. ii. biochemical studies of esterase-5 in d. pseudoobscura.in vitro enzyme hybridization was carried out with combinations of six allozymic variants of esterase-5 from drosophila pseudoobscura. studies on heat stability and specific activity changes accompanying hybridization were done to examine the possible expression of overdominance at the biochemical level. in 11 of 15 combinations no significant change in specific activity was found following hybridization. in two cases hybridization resulted in a decrease in activity in the mixture, while in two ...19744455554
genetic background and the fitness of allozymes.experimental perturbations of gene frequency at the esterase-5 locus in drosophila pseudoobscura were carried out in a series of population cages started with differing numbers of founder chromosomes. cages founded with few chromosomes showed changes in gene frequency at the allozyme locus. such changes were less marked in cages founded with a larger sample of chromosomes. these experiments show the importance of linkage disequilibrium in affecting allozyme frequencies, and emphasize the necessi ...19744455555
dosage compensation of genes on the left and right arms of the x chromosome of drosophila pseudoobscura and drosophila willistoni.we have investigated the occurrence of dosage compensation in d. willistoni and d. pseudoobscura, two species whose x chromosome is metacentric with one arm homologous to the x and the other homologous to the left arm of chromosome 3 of d. melanogaster. crude extracts were assayed for isocitrate dehydrogenase (xr), glucose-6-phosphate dehydrogenase (xl?), 6-phosphogluconate dehydrogenase (xl?), and alpha-glycerophosphate dehydrogenase (chromosome 2) in d. willistoni, and for esterase-5 (xr), glu ...19744455556
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