Project description:Investigation of sex-biased expression across species have relied on measurements from whole flies which sample the extensive expression differences found in the germline and gonads of females and males. We wanted to examine genes with sex-biased expression in a somatic tissue to analyze patterns of genes with sex-biased expression in the context of a tissue more phenotypically similar between females and males. We used a Nimblegen microarray designed for Drosophila melanogaster and two custom micoarrays designed for D. pseudoobscura and D. mojavensis to survey gene expression differences in heads of females and males.
Project description:Investigation of sex-biased expression across species have relied on measurements from whole flies which sample the extensive expression differences found in the germline and gonads of females and males. We wanted to examine genes with sex-biased expression in a somatic tissue to analyze patterns of genes with sex-biased expression in the context of a tissue more phenotypically similar between females and males. We used a Nimblegen microarray designed for Drosophila melanogaster and two custom micoarrays designed for D. pseudoobscura and D. mojavensis to survey gene expression differences in heads of females and males. PolyA+ mRNA was isolated in quadruplicate from dissected heads of 8 day old adult females and males. Female and male mRNA were labeled with Cy3 or Cy5 dyes separately and co-hybridized to species-specific microarrays. We analyzed a total of 24 channels of data.
Project description:Background: Stalk-eyed flies (family Diopsidae) are a model system for studying sexual selection due to the presence of elongated and sexually dimorphic eye-stalks in many species. Recent genomic studies on these flies have revealed a neo-X chromosome and evidence of gene movement onto or off of this X chromosome. To determine if sex linkage and gene movement are related to sexual dimorphism and sexual conflict, we compared gene expression between males and females using oligonucleotide microarrays and RNA from either developing eyestalk tissue or adult heads from a dimorphic species, Teleopsis dalmanni, or from developing eyestalk tissue in a congeneric monomorphic species, T. quinqueguttata. Results: Comparison of gene expression between the sexes for 3,748 genes indicates that dosage compensation is present due to elevated expression of X-linked genes in males. However, sex-biased expression was detected in 26% of the genes present in eye-antennal imaginal discs of larval T. dalmanni. Functional annotation reveals that female-biased genes are associated with transcription, anatomical development and cell communication in the nucleus, while male-biased genes are associated with metabolism and the mitochondria. Comparison of gene expression between experiments identified 140 genes with concordant sex-biased expression in the larval and adult tissues of T. dalmanni and 17 genes with identical sex-biased expression between species. There were only five reversals of sex-biased expression across experiments. In T. dalmanni, male-biased genes are more common on autosomes than on the X while female-biased genes are more common on the X in T. quinqueguttata. Female-biased expression is especially common among genes that moved onto the ancestral X while male-biased expression is more common among genes that moved onto an autosome. Conclusions: Genes with sex-biased expression exhibit different functions in each sex as expected if sexual conflict has influenced their evolution. The strong relationship between sex-biased expression and gene movement found in this study is consistent with resolution of sexual conflict by an RNA- or DNA-mediated process that moves genes between chromosomes. Measurement of gene expression in additional species should provide a more complete picture of how gene expression change occurs over evolutionary time in these extraordinary flies. Two-condition experiment, female vs. male RNA using larval eye discs for two species (Teleopsis dalmanni, Teleopsis quinqueguttata), and adult heads for one species (Teleopsis dalmanni).
Project description:Extensive sex-biased expression has been seen in multiple surveys D. melanogaster. We were interested in broadly sampling sex-biased expression of orthologs and species- or lineage-specific genes in the Drosophila genus. To appropriately assay gene expression in multiple species, we used custom microarrays designed against each of six species that broadly sample the phylogenetic space represented by the newly completed genomes (D. simulans, D. yakuba, D. ananassae, D. pseudoobscura, D. virilis and D. mojavensis) and an array designed against D. melanogaster to determine the overall patterns of sex-biased expression in those species and their chromosome linkage. Keywords: other
Project description:Investigatation into how genes with sex-differential expression profiles are distributed among the chromosomes in Drosophila. Assayed the expression of 14,142 predicted transcripts in competitive hybridizations and found a dramatic underrepresentation of X-chromosome genes showing high relative expression in male. This is the first report of sex-biased expression of the full (predicted) genome. Findings indicate that there is significant sex-biased expression, especially in gonads. Genes showing sex-biased gene expression profiles are likely to have sex-biased functions. Keywords: other
Project description:Extensive sex-biased expression has been seen in multiple surveys D. melanogaster. We were interested in broadly sampling sex-biased expression of orthologs and species- or lineage-specific genes in the Drosophila genus. To appropriately assay gene expression in multiple species, we used custom microarrays designed against each of six species that broadly sample the phylogenetic space represented by the newly completed genomes (D. simulans, D. yakuba, D. ananassae, D. pseudoobscura, D. virilis and D. mojavensis) and an array designed against D. melanogaster to determine the overall patterns of sex-biased expression in those species and their chromosome linkage. Keywords: other PolyA+ mRNA in duplicate were isolated from 5-7 day old adult females and males of seven drosophila species. Male and female mRNA was labeled by Cy3 or Cy5 dye separately and hybridized simultaneously to the appropriate species-specific arrays. We performed at least four two-channel hybridizations for each species including two biological replicates and dye-swaps for each of them. Only single channels which passed stringent pre-processing quality control were used. A total of 67 channels of data were used in the final analysis.
Project description:Genes with sex-biased expression in adults experience unique evolutionary dynamics. It is unclear, however, whether the selection pressures responsible for these well documented patterns also act upon genes with sex-biased expression in other developmental stages. To examine this, we measured expression in male and female Drosophila melanogaster larvae.
Project description:The effect of germline tissue on somatic sex-biased expression is examined. Expression is assayed in various adult tissues with germline ablated directly or genetically. The effect of germline signalling on sex-biased expression in the Drosophila head is also examined. Keywords: Expression profiling
Project description:Stalk-eyed flies (family Diopsidae) are a model system for studying sexual selection due to the elongated and sexually dimorphic eye-stalks found in many species. These flies are of additional interest because their X chromosome is derived largely from an autosomal arm in other flies. To identify candidate genes required for development of dimorphic eyestalks and investigate how sex-biased expression arose on the novel X we compared gene expression between males and females using oligonucleotide microarrays and RNA from developing eyestalk tissue or adult heads in the dimorphic diopsid, Teleopsis dalmanni. Microarray analysis revealed sex-biased expression for 26% of 3,748 genes expressed in eye-antennal imaginal discs and concordant sex-biased expression for 86 genes in adult heads. Overall, 415 female-biased and 482 male-biased genes were associated with dimorphic eyestalk development but not differential expression in the adult head. Functional analysis revealed that male-biased genes are disproportionately associated with growth and mitochondrial function while female-biased genes are associated with cell differentiation and patterning or are novel transcripts. With regard to chromosomal effects, dosage compensation occurs by elevated expression of X-linked genes in males. Genes with female-biased expression were more common on the X and less common on autosomes than expected, while male-biased genes exhibited no chromosomal pattern. Rates of protein evolution were lower for female-biased genes but higher for genes that moved on or off the novel X chromosome. These findings cannot be due to meiotic sex chromosome inactivation or by constraints associated with dosage compensation. Instead, they could be consistent with sexual conflict in which female-biased genes on the novel X act primarily to reduce eyespan in females while other genes increase eyespan in both sexes. Additional information on sex-biased gene expression in other tissues and related sexually monomorphic species could confirm this interpretation.