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: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
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:In this study, we utilized Comparative Genomic Hybridization (CGH), using probes designed from EST sequence, to identify genes located on the X chromosome of four species in the stalk-eyed fly genus Teleopsis. Analysis of log ratio values from the CGH microarrays for over 3400 genes produces a strongly bimodal distribution that clearly differentiates autosomal from X-linked genes for all four species. Genetic mapping of 35 of these genes in T. dalmanni indicates the CGH results correctly identified chromosomal location in all cases. Syntenic comparison with Drosophila indicates that 90% of the X-linked genes in Teleopsis are homologous to genes located on chromosome 2L in D. melanogaster, suggesting the formation of a nearly complete neo-X chromosome from Muller element B in the Dipteran lineage leading to Teleopsis. Overall, this study demonstrates CGH is a useful technique for identifying chromosomal sex-linkage and should be applicable to other organisms with EST or partial genomic information.
Project description:In this study, we utilized Comparative Genomic Hybridization (CGH), using probes designed from EST sequence, to identify genes located on the X chromosome of four species in the stalk-eyed fly genus Teleopsis. Analysis of log ratio values from the CGH microarrays for over 3400 genes produces a strongly bimodal distribution that clearly differentiates autosomal from X-linked genes for all four species. Genetic mapping of 35 of these genes in T. dalmanni indicates the CGH results correctly identified chromosomal location in all cases. Syntenic comparison with Drosophila indicates that 90% of the X-linked genes in Teleopsis are homologous to genes located on chromosome 2L in D. melanogaster, suggesting the formation of a nearly complete neo-X chromosome from Muller element B in the Dipteran lineage leading to Teleopsis. Overall, this study demonstrates CGH is a useful technique for identifying chromosomal sex-linkage and should be applicable to other organisms with EST or partial genomic information. Two-condition experiment, female vs. male DNA, for four species, each with 4 biological replicates
Project description:Comparative Genomic Hybridization (CGH) reveals sex chromosome location and gene movement in stalk-eyed flies (family Diopsidae), Teleopsis quinqueguttata