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 some species. These flies are of additional interest because their X chromosome is derived largely from an autosomal arm in other flies. To 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 in the sexually monomorphic diopsid, Teleopsis quinqueguttata. We use probe sequence divergence to evaluate cross-species ascertainment bias and chromosome assignment to determine if sex linkage influence expression. Microarray analysis revealed sex-biased expression for only 1.9% of 3,748 genes expressed in eye-antennal imaginal discs. Analysis of probe sequences between species indicates that the lack of sex-biased expression is not due to ascertainment bias. These findings indicate that the the majority of sex-biased gene expression observed in developing heads of the dimorphic species, T. dalmanni, is causally related to development of dimorphic head shape. Two-condition experiment, female vs. male RNA using larval eye discs and adult heads for one species (Teleopsis quinqueguttata)
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 some species. These flies are of additional interest because their X chromosome is derived largely from an autosomal arm in other flies. To 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 in the sexually monomorphic diopsid, Teleopsis quinqueguttata. We use probe sequence divergence to evaluate cross-species ascertainment bias and chromosome assignment to determine if sex linkage influence expression. Microarray analysis revealed sex-biased expression for only 1.9% of 3,748 genes expressed in eye-antennal imaginal discs. Analysis of probe sequences between species indicates that the lack of sex-biased expression is not due to ascertainment bias. These findings indicate that the the majority of sex-biased gene expression observed in developing heads of the dimorphic species, T. dalmanni, is causally related to development of dimorphic head shape.
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.
Project description:We utilized Comparative Genomic Hybridization (CGH), using probes designed from de novo assembly of a testes transcriptome, to identify genes located on the sex chromosomes and autosomes of a stalk-eyed fly, Teleopsis quinqueguttata. Analysis of X chromosome gene content revealed the evolution of a neo-X chromosome that originated prior to the diversification of the family. Comparison of X-linkage across three species spanning the phylogenetic breadth of the family indicates abundant chromosomal gene movement, particularly for genes expressed exclusively in the testes.
Project description:Data from whole-body, head, thorax, abdomen, ovaries, testes and accessory glands was used to assess possible causes of a non-random distribution of sex-biased genes (sexually dimorphic expression). All samples were derived from virgin adult flies.
Project description:Objective: Sexually dimorphic phenotypes arise largely from sex-specific gene expression, which has mainly been characterized in sexually naïve adults. However, we expect sexual dimorphism in transcription to be dynamic and dependent on factors such as reproductive status. Mating induces many behavioral and physiological changes distinct to each sex and is therefore expected to activate regulatory changes in many sex-biased genes. Methods: Using RNA-seq we first characterized sexual dimorphism in gene expression, for the first time in Callosobruchus maculatus seed beetles. We then examined how females and males respond to mating and how it affects sex-biased expression, both in more sex-limited (abdomen) and sex-shared (head and thorax) tissues. Results: Mating responses were largely sex-specific and, as expected, females showed more numerous changes compared to males. Of the sex-biased genes present in virgins, 16% (1,041 genes) in the abdomen and 17% (243 genes) in the head and thorax altered their relative expression between the sexes. Sex-bias status changed in 2% of the genes in the abdomen and 4% in the head and thorax following mating. Mating responses involved de-feminization of females and, to a lesser extent, de-masculinization of males relative to their virgin state: mating decreased rather than increased dimorphic expression of sex-biased genes.
Project description:We utilized Comparative Genomic Hybridization (CGH), using probes designed from de novo assembly of a testes transcriptome, to identify genes located on the sex chromosomes and autosomes of a stalk-eyed fly, Teleopsis quinqueguttata. Analysis of X chromosome gene content revealed the evolution of a neo-X chromosome that originated prior to the diversification of the family. Comparison of X-linkage across three species spanning the phylogenetic breadth of the family indicates abundant chromosomal gene movement, particularly for genes expressed exclusively in the testes. Two-condition experiment, female vs. male DNA, for one species with 3 biological replicates