Project description:Purpose: Accurate identification of sex-biased genes requires precise measurement of gene expression levels in gonads. This study is designed to provide such data for various Drosophila species to enhance studies of sex-biased gene expression and evolution across the genus. Methods: Virgin flies were collected and aged 6-10 days before dissecting 2-3 replicates of testes or ovaries. Total RNA was extracted using the Arcturus® PicoPure® kit . Illumina® TruSeq® RNA library kits were used to poly-A+ select and reverse-transcribe mRNA, shear cDNA into ~120 bp fragments, and produce libraries for 1x50 bp sequencing on an Illumina GAIIx or HiSeq2000. Illumina®’s Real Time Analysis v1.13 module processed images, called bases, and provided base qualities. Reads were mapped to the current reference genomes using Bowtie v2.1.0 (Langmead and Salzberg, 2012, Nat Meth) with default settings. Differentially expressed genes were detected using Cufflinks v 2.1.0 (Trapnell et al., 2010, Nat Biotech; default settings) or edgeR (Robinson et al., 2010, Bioinformatics; full-quantile GC-content normalization and full-quantile between-sample normalization). Genes were called differentially expressed at a Benjamini-Hochberg false discovery rate of 0.01. Results: Thousands of male- and female-biased genes were detected for each species using both DE detection methods. These results provide a significant improvement in sensitivity of sex-biased gene detection relative to using whole-body RNA-sequencing data. These data provide a foundation for accurate identification of sex-biased genes throughout the Drosophila genus.
Project description:Purpose: Accurate identification of sex-biased genes requires precise measurement of gene expression levels in gonads. This study is designed to provide such data for various Drosophila species to enhance studies of sex-biased gene expression and evolution across the genus. Methods: Virgin flies were collected and aged 6-10 days before dissecting 2-3 replicates of testes or ovaries. Total RNA was extracted using the Arcturus® PicoPure® kit . Illumina® TruSeq® RNA library kits were used to poly-A+ select and reverse-transcribe mRNA, shear cDNA into ~120 bp fragments, and produce libraries for 1x50 bp sequencing on an Illumina GAIIx or HiSeq2000. Illumina®’s Real Time Analysis v1.13 module processed images, called bases, and provided base qualities. Reads were mapped to the current reference genomes using Bowtie v2.1.0 (Langmead and Salzberg, 2012, Nat Meth) with default settings. Differentially expressed genes were detected using Cufflinks v 2.1.0 (Trapnell et al., 2010, Nat Biotech; default settings) or edgeR (Robinson et al., 2010, Bioinformatics; full-quantile GC-content normalization and full-quantile between-sample normalization). Genes were called differentially expressed at a Benjamini-Hochberg false discovery rate of 0.01. Results: Thousands of male- and female-biased genes were detected for each species using both DE detection methods. These results provide a significant improvement in sensitivity of sex-biased gene detection relative to using whole-body RNA-sequencing data. These data provide a foundation for accurate identification of sex-biased genes throughout the Drosophila genus. Testis and ovary samples from Drosophila species were sequenced 1 x 50 bp in duplicate from 6-10 day old virgin, Wolbachia-free adult flies on an Illumina GAIIx or HiSeq2000.
Project description:A microarray study of sex- and gonad-biased gene expression was conducted to determine whether zebrafish demonstrate male-specific patterns consistent with those observed in other animals. We identified a large number of genes (5899) demonstrating statistical differences in transcript abundance between male and female Danio rerio. All sex-biases in gene expression were due to differences between testis and ovary, although differences between male and female body likely went undetected due to constraints imposed by study design and statistical criteria. Male-enriched genes were more abundant than female-enriched genes, and the magnitude of expression bias for male-enriched genes was greater than that for female-enriched genes. We also identified a large number of candidate reproductive genes based on elevated transcript abundance in testes and ovaries, relative to male body and female body, respectively. Gene expression patterns in adult zebrafish from this study are consistent with the male-biased patterns typical of most animal taxa studied to date. Recent zebrafish studies designed to address more specific questions have not reported the same findings, but major methodological and analytical differences across these studies could explain discrepancies.
Project description:The contrasting dose of sex chromosomes in males and females potentially introduces a large-scale imbalance in levels of gene expression between sexes. In many organisms dosage compensation has thus evolved to equalize sex-linked gene expression in males and females1,2, in mammals achieved by X chromosome inactivation and in flies and worms by up- or down-regulation of X-linked expression, respectively. Another form of dosage compensation ensures that expression levels on the X chromosome and on autosomes are balanced3,4. While otherwise widespread in systems with heteromorphic sex chromosomes, the case of dosage compensation in birds (males ZZ, females ZW) remains an unsolved enigma5,6. Here we use a microarray approach to show that male day 18 chicken embryos generally express higher levels of Z-linked genes than female birds, both in soma and in gonads. The distribution of male-to-female fold-change values for Z chromosome genes is wide and has a mean of 1.4-1.6, which is consistent with absence of dosage compensation and sex-specific feedback regulation of gene expression at individual loci2. Intriguingly, without global dosage compensation, female chicken has significantly lower expression levels of Z-linked compared to autosomal genes, which is not the case in male birds. The pronounced sex difference in gene expression is likely to contribute to sexual dimorphism among birds, and potentially has implication to avian sex determination. Keywords: dosage compensation, sex-biased gene expression, soma and gonad
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:In this study, three small RNA libraries constructed from gonad tissues of XX female, XY male and YY super-male yellow catfish were sequenced by Solexa high-throughput sequencing technology to investigate the expression pattern of sex-biased microRNA. The sequencing data generated a total of 384 conserved miRNAs and 113 potential novel miRNAs, among which 23, 30 and 14 miRNAs were specifically detected in XX ovary, XY testis, and YY testis, respectively. Interestingly, more abundant piRNAs were found in ovary compared to testis in yellow catfish, which phenomenon is also observed in other fish species but opposite in mammalians. We detected a number of microRNAs differentially expressed between ovary and testis, such as miR-21, miR-462, miR-430 and -200 family. When compared the transcriptome between XY and YY testis, we observed relative lower expression of miR-141 and miR-429 in YY testis. Histological analysis indicated that YY super-males have more spermatids and less spermatocytes in spermatogenic cyst than XY males under the same age and culturing conditions. The expression level of miR-141 and 429 coincides with the progression of spermatogenesis both in yellow catfish and human. At last, The expression pattern of nine arbitrarily selected miRNAs detected by quantitative RT-PCR was consistent with the Solexa sequencing results. Our study provides a comprehensive miRNA transcriptome analysis for gonad of yellow catfish with different sex genotypes, and identifies a number of sex-biased miRNAs that are potentially involved in sex differentiation and spermatogenesis.
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. Drosophila melanogaster wandering third instar larvae were sexed using the visible gonad. RNA was isolated from three replicate samples of male and female larvae and one sample each of adult males and females. RNA was prepared following the manufacturer's instructions, using single color labelling. Each sample/replicate was hybridized to one sector of the Agilent 4 sector array (a total of two arrays were used), with the following design: Array 1 had one larval male sample, one larval female sample, one adult male sample, and one adult female sample; Array 2 had two larval male samples and two larval female samples.
Project description:Sexual dimorphism depends on sex-biased gene expression, but the contributions of microRNAs (miRNAs) have not been globally assessed. We therefore produced an extensive small RNA sequencing dataset to analyse male and female miRNA expression profiles in mouse, opossum and chicken. Our analyses uncovered numerous cases of somatic sex-biased miRNA expression, especially in the mouse heart and liver. Sex-biased expression is explained by miRNA-specific regulation, including sex-biased chromatin accessibility at promoters, rather than piggybacking of intronic miRNAs on sex-biased protein-coding genes. In mouse, but not opossum and chicken, sex bias is coordinated across tissues such that autosomal testis-biased miRNAs tend to be somatically male-biased, whereas autosomal ovary-biased miRNAs are female-biased, possibly due to broad hormonal control. In chicken, which has a Z/W sex chromosome system, expression output of genes on the Z chromosome is expected to be male-biased, since there is no global dosage compensation mechanism that restores expression in ZW females after almost all genes on the W chromosome decayed. Nevertheless, we found that the dominant liver miRNA, miR-122-5p, is Z-linked but expressed in an unbiased manner, due to the unusual retention of a W-linked copy. Another Z-linked miRNA, the male-biased miR-2954-3p, shows conserved preference for dosage-sensitive genes on the Z chromosome, based on computational and experimental data from chicken and zebra finch, and acts to equalise male-to-female expression ratios of its targets. Unexpectedly, our findings thus establish miRNA regulation as a novel gene-specific dosage compensation mechanism.
Project description:Although not all sex-dependent gene expression is adaptive, it is likely an important genomic mechanism that allows each sex to independently adapt to environmental changes. Among Drosophila species, sex-biased genes display remarkably consistent evolutionary patterns; male-biased genes evolve faster than unbiased genes in both coding sequence and expression level, suggesting sex-differences in selection through time. However, comparatively little is known of the evolutionary process shaping sex-biased expression within species. Latitudinal clines offer an opportunity to examine how changes in key ecological parameters also influence sex-specific selection and the evolution of sex-biased gene expression. We assayed male and female gene expression in Drosophila serrata along a latitudinal gradient in eastern Australia spanning most of its endemic distribution. Analysis of 11,631 genes across eight populations revealed strong sex differences in the frequency, mode, and strength of divergence. Divergence was far stronger in males than females and while latitudinal clines were evident in both sexes, male divergence was often population-specific, suggesting responses to localized selection pressures that do not covary predictably with latitude. While divergence was enriched for male-biased genes, there was no overrepresentation of X-linked genes in males. By contrast, X-linked divergence was elevated in females, especially for female biased genes. Many genes that diverged in D. serrata have homologs also showing latitudinal divergence in D. simulans and D. melanogaster on other continents, likely indicating parallel adaptation in these distantly related species. Our results suggest that sex differences in selection play an important role in shaping the evolution of gene expression over macro- and micro-ecological spatial scales.
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.