Project description:In this work, we evaluated the genetic stabilization process, of the intra- (Saccharomyces cerevisiae) and interspecific (S. cerevisiae x Saccharomyces kudriavzevii) hybrids obtained by different non-GMO techniques, under fermentative conditions. Large-scale transitions in genome size, detected by measuring total DNA content, and genome reorganizations in both nuclear and mitochondrial DNA, evidenced by changes in molecular markers, were observed during the experiments. Interspecific hybrids seem to need fewer generations to reach genetic stability than intraspecific hybrids. The largest number of molecular patterns among the derived stable colonies was observed for intraspecific hybrids, particularly for those obtained by rare-mating in which the total amount of initial DNA was larger. Finally, a representative intraspecific stable hybrid underwent a normal industrial process to obtain active dry yeast production as an important point at which inducing changes in genome composition was possible. No changes in hybrid genetic composition after this procedure were confirmed by comparative genome hybridization. According to our results, fermentation steps 2 and 5 –comprising between 30 and 50 generations- suffice to obtain genetically stable interspecific and intraspecific hybrids, respectively. This work aimed to develop and validate a fast genetic stabilization method for newly generated Saccharomyces hybrids under selective enological conditions. A comparison of the whole stabilization process in intra- and interspecific hybrids showing different ploidy levels, as a result of using different hybridization methodologies, was also made.
Project description:we identify Scml2, a subunit of a germ cell-specific polycomb repressive complex 1 (PRC1), as a critical epigenetic modifier that establishes the germline-specific epigenome through two distinct functions. One of these functions is in the stem cell phase of spermatogonia and the other is on meiotic sex chromosomes. During the stem cell phase of spermatogonia, Scml2 establishes Rnf2- dependent ubiquitination of H2A (Rnf2-ubH2A) as an epigenetic memory that subsequently ensures programmed repression of somatic genes during the late stages of spermatogenesis. Additionally, during meiosis, Scml2 interacts with M-NM-3H2AX and works downstream of the DNA damage response factor Mdc1 on the sex chromosomes and, contrary to autosomes, suppresses Rnf2-ubH2A for proper epigenetic programming of the sex chromosomes. Taken together, Scml2 positively regulates Rnf2-ubH2A on autosomes and negatively regulates Rnf2-ubH2A on the sex chromosomes to establish the germline-specific epigenome in spermatogenesis. Our study reveals a novel layer of epigenetic regulation in the male germline and adds further insight into the functionality of the polycomb proteins. RNA-seq and ChIP-seq analyses using wild-type and Scml2 KO spermatogenic cells
Project description:In this work, we evaluated the genetic stabilization process, of the intra- (Saccharomyces cerevisiae) and interspecific (S. cerevisiae x Saccharomyces kudriavzevii) hybrids obtained by different non-GMO techniques, under fermentative conditions. Large-scale transitions in genome size, detected by measuring total DNA content, and genome reorganizations in both nuclear and mitochondrial DNA, evidenced by changes in molecular markers, were observed during the experiments. Interspecific hybrids seem to need fewer generations to reach genetic stability than intraspecific hybrids. The largest number of molecular patterns among the derived stable colonies was observed for intraspecific hybrids, particularly for those obtained by rare-mating in which the total amount of initial DNA was larger. Finally, a representative intraspecific stable hybrid underwent a normal industrial process to obtain active dry yeast production as an important point at which inducing changes in genome composition was possible. No changes in hybrid genetic composition after this procedure were confirmed by comparative genome hybridization. According to our results, fermentation steps 2 and 5 –comprising between 30 and 50 generations- suffice to obtain genetically stable interspecific and intraspecific hybrids, respectively. This work aimed to develop and validate a fast genetic stabilization method for newly generated Saccharomyces hybrids under selective enological conditions. A comparison of the whole stabilization process in intra- and interspecific hybrids showing different ploidy levels, as a result of using different hybridization methodologies, was also made. A stable hybrid strain was compared with itself before and after ADY (active dry yeast) production in order to evaluate the genetic stability of this strain.
Project description:Here, we set out to understand the extent and nature of epigenomic changes associated with sexual differentiation in the brown alga Ectocarpus, which has a well described UV system. Five histone modifications, H3K4me3, H3K27Ac, H3K9Ac, H3K36me3, H4K20me3, were quantified in near-isogenic male and female lines, leading to the identification of 13 different chromatin states across the Ectocarpus genome that showed different patterns of enrichment at transcribed, silent, housekeeping or narrowly-expressed genes. Chromatin states were strongly correlated with levels of gene expression indicating a relationship between the assayed marks and gene transcription. The relative proportion of each chromatin state across the genome remained stable in males and females, but a subset of genes exhibited different chromatin states in the two sexes. In particular, males and females displayed distinct patterns of histone modifications at sex-biased genes, indicating that chromatin state transitions occur preferentially at genes involved in sex-specific pathways. Finally, our results reveal the unique chromatin landscape of the U and V sex chromosomes compared to autosomes. Taken together, our observations reveal a role for histone modifications in sex determination and sexual differentiation in a UV sexual system, and suggest that the mechanisms of epigenetic regulation of genes on the U/V sex chromosomes may differ from those operating on autosomal genes.
Project description:Using reduced representation bisulfite sequencing (RRBS), we have compared the methylomes of neuronal and non-neuronal cells from three female human and three chimpanzee cortices (Brodmann area 10). Differentially methylated regions (DMRs) with genome-wide significance were enriched in specific chromosomal regions. Intraspecific methylation differences between neuronal and non-neuronal cells were approximately three times more abundant than interspecific methylation differences between human and chimpanzee cell types. The vast majority (>90%) of human intraspecific DMRs (including DMRs with retrotransposons) were hypomethylated in neurons, compared to glia. Intraspecific DMRs were enriched in genes that have been associated with different neuropsychiatric disorders. Interspecific DMRs were enriched in genes showing human-specific brain histone modifications. Methylation differences between human and chimpanzee non-neuronal cells (N=666) were much more frequent than neuronal interspecific DMRs (N=96). More than 95% of interspecific non-neuronal DMRs were hypermethylated in humans.
Project description:A number of genes associated with sexual traits and reproduction evolve at the sequence level faster than the majority of genes coding for non-sex-related traits. Whole genome analyses allow this observation to be extended beyond the limited set of genes that have been studied thus far. We use cDNA microarrays to demonstrate that this pattern holds in Drosophila for the phenotype of gene expression as well, but in one sex only. Genes that are male-biased in their expression show more variation in relative expression levels between conspecific populations and two closely related species than do female-biased genes or genes with sexually monomorphic expression patterns. Additionally, elevated ratios of interspecific expression divergence to intraspecific expression variation among male-biased genes suggest that differences in rates of evolution may be due in part to natural selection. This finding has implications for our understanding of the importance of sexual dimorphism for speciation and rates of phenotypic evolution. Keywords: other
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:Sex differences in the brain as they relate to health and disease are often overlooked in experimental models. Many neurological disorders, like Alzheimer’s disease (AD), multiple sclerosis (MS), and autism, differ in prevalence between males and females. Sex differences originate either from differential gene expression on sex chromosomes or from hormonal differences, either directly or indirectly. To disentangle the relative contributions of genetic sex (XX v. XY) and gonadal sex (ovaries v. testes) to the regulation of hippocampal sex effects, we use the “sex-reversal” Four Core Genotype (FCG) mouse model which uncouples sex chromosome complement from gonadal sex. Transcriptomic and epigenomic analyses of hippocampal RNA and DNA from ∼12 month old FCG mice, reveals differential regulatory effects of sex chromosome content and gonadal sex on X- versus autosome-encoded gene expression and DNA modification patterns. Gene expression and DNA methylation patterns on the X chromosome were driven primarily by sex chromosome content, not gonadal sex. The majority of DNA methylation changes involved hypermethylation in the XX genotypes (as compared to XY) in the CpG context, with the largest differences in CpG islands, promoters, and CTCF binding sites. Autosomal gene expression and DNA modifications demonstrated regulation by sex chromosome complement and gonadal sex. These data demonstrate the importance of sex chromosomes themselves, independent of hormonal status, in regulating hippocampal sex effects. Future studies will need to further interrogate specific CNS cell types, identify the mechanisms by which sex chromosome regulate autosomes, and differentiate organizational from activational hormonal effects.
Project description:Blastocyst-derived embryonic stem cells (ESCs) and gonad-derived embryonic germ cells (EGCs) represent two classic types of pluripotent cell lines, yet their molecular equivalence remains incompletely understood. Here, we compare genome-wide methylation patterns between isogenic ESC and EGC lines to define epigenetic similarities and differences. Surprisingly, we find that sex rather than cell type drives methylation patterns in ESCs and EGCs. Cell fusion experiments further reveal that the ratio of X-chromosomes to autosomes dictates methylation levels, with female hybrids being hypomethylated and male hybrids being hypermethylated. We show that the X-linked MAPK phosphatase DUSP9 is upregulated in female compared to male ESCs, and its heterozygous loss in female ESCs leads to male-like methylation levels. Notably, male and female blastocysts are similarly hypomethylated, indicating that sex-specific methylation differences arise in culture. Collectively, our data demonstrate the epigenetic similarity of sex-matched ESCs and EGCs and identify DUSP9 as a regulator of female-specific hypomethylation.