Project description:The goals of this study are to compare genome-wide DNA methylation levels in young and aged oocytes,and to investigate the transgenerational inheritance of methylome profiles in oocytes during natural aging. We apply a novel protocol of rapamycin to overcome the DNA methylation drift associated with oocyte aging. 8-week-old female mice were injected intraperitoneally with rapamycin or vehicle for 40 weeks. At the end of the experiment, females (48 weeks, F0) were paired with young adult (~4 mo old) males to produce F1 offspring (OF1 and ORaF1). An F2 generation (OF2 and ORaF2) resulted from mating F1 female at 44~48 weeks of age with young adult males. To generate YF1 and YF2 as normal control (offspring of young mother), we mated females (~8 weeks) with young adult males. Then we collect oocytes (F0,F1 and F2 generations),sperm ( F1 and F2 generations) and hippocampus (F1 female offspring) from different groups to investigate the transgenerational inheritance of DNA methylome profiles associated with oocyte aging by the single cell whole-genome methylation sequencing (sc-WGBS). We found that oocytes from aged mother exhibited increased DNA methylation levels in CpG sites. Maternal aging related methylome changes can be inherited transgenerationally though oocyte to the germ line of F1 and F2 offspring. The application of rapamycin during the course of oocyte aging could reverse these DNA methylation alterations, and it can ameliorate several neurobehavioral aging trails that were in observed in aged oocyte offspring. WGBS-seq on DNA from hippocampal tissue revealed a number of differentially methylated (P<0.05) genes in OF1 and ORaF1 compared with YF1, and some of the enriched pathways were associated with aging process, such as PI3K-Akt signaling pathway (akin to transcriptional alterations above), MAPK signaling and Ras signaling pathway .
Project description:Oocyte maturation refers to oocytes at the germinal vesicle stage progressing into metaphase II (MII) stage of development. Even though numerous studies have shown key genes and potential important signalling cascades, which drive the GV to MII transition, a system-wide analysis of underlying differences at gene level and especially at transcript level between the two developmental stages of the oocyte is still lacking. For this, we profiled and analysed RNA from pig oocytes across meiotic maturation (GV, MII and damaged, n=15). We detected 22,516 genes for each sample across meiotic maturation. Principal Component analysis of the data clustered the samples in three stages of development (GV, MII and damaged). Differential expression of genes between the three stages will then be used to delineate the pathways which are up-/down-regulated during these developmental stages. Besides, differential transcript usage will be used to identify the difference of oocytes at distinct developmental stages at isoform level, which might be ignored by traditional differential gene expression analysis.
Project description:Somatic cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from late vitellogenic females (LV), C1 samples from post-vitellogenic females (PV), and C2 samples from females undergoing meiotic maturation (Germinal Vesicle Breakdown) Global transcriptional profiling was performed using somatic cells collected from rainbow trout ovarian follicles during in vivo oocyte developmental competence acquisition. Somatic cells were collected at 3 stages of oogenesis: NC1 stage follicles (LV, late vitellogenic, prophase I arrested oocytes, meiotically incompetent and developmentally incompetent, n=6), C1 stage follicles (PV, post-vitellogenic, prophase I arrested oocytes, meiotically competent and developmentally competent, n=16). Ovulatory follicles were also collected during oocyte maturation after in vivo induction (metaphase II arrested oocytes, developmentally fully competent, n=6).
Project description:Whole genome bisulfite sequencing (WGBS) was used to assess the effect of M. bovis infection on the bAM DNA methylome (5-methylcytosine). The methylomes of bAM infected with M. bovis (n = 8) were compared to those of non-infected control bAM (n = 8) at 24 hours post-infection (hpi). No differences in DNA methylation (CpG or non-CpG) were observed between control and infected bAM. Analysis of DNA methylation at proximal promoter regions uncovered >250 genes harbouring intermediately methylated (IM) promoters (average methylation = 33–66%). Gene ontology (GO) analysis, focusing on genes with low, intermediate or highly methylated promoters, revealed that genes with IM promoters were enriched for immune-related GO categories; this enrichment was not observed for genes in the high or low methylation groups. Targeted analysis of two non-imprinted genes in the IM category, C1QB and IL2RA, confirmed the WGBS observation. This study is the first in cattle to examine genome-wide DNA methylation at single nucleotide resolution in an important bovine cellular host-pathogen interaction model and provides evidence for intermediate promoter methylation in bAM.
Project description:5-methylcytosine is a major epigenetic modification sometimes called "the fifth nucleotide". However, our knowledge of how offspring inherit the DNA methylome from parents is limited. We generated nine single-base resolution DNA methylomes including zebrafish gametes and early embryos. The oocyte methylome is significantly hypo-methylated compared to sperm. Strikingly, the paternal DNA methylation pattern is maintained throughout early embryogenesis. The maternal DNA methylation pattern is maintained until the 16-cell stage. Then, the oocyte methylome is gradually discarded through cell division, and progressively reprogrammed to a pattern similar to that of the sperm methylome. The passive demethylation rate and the de novo methylation rate are similar in the maternal DNA. By the midblastula stage, the embryo?s methylome is virtually identical to the sperm methylome. Moreover, inheritance of the sperm methylome facilitates the epigenetic regulation of embryogenesis. Therefore, besides DNA sequences, sperm DNA methylome is also inherited in zebrafish early embryos.
Project description:In order to obtain genome-wide profiles, base-resolution methylomes of oocytes and zygotes were generated using the bisulfite sequencing (BS-seq) method for small samples. We find that global loss of DNA methylation during zygotic development in HFD mice. A total of 412 DMRs were identified, of which 294 were hypomethylated (hypo-DMRs; 71.4%) and 118 were hypermethylated (hyper-DMRs; 28.6%) (Fig. 6A and 6B), showing a predominance of hypo-DMRs. Furthermore, we show that hyper-DMRs are significantly depleted from CGI, but enriched in short interspersed elements (SINEs) and non-CGI regions. Strikingly, hypo-DMRs are specifically depleted from SINEs, with a concurrent enrichment in DNA transposons.
Project description:Using WGBS we investigated blood DNA methylation profiles of German Shepherd and determined putative regulatory elements (unmethlated regions (UMRs) and lowly methylated regions (LMRs).
Project description:During female germline development oocytes become a highly specialized cell type, and form a maternal cytoplasmic store of crucial factors during oocyte growth. Oocyte growth is triggered at the primordial-primary follicle transition accompanied with dynamic changes in gene expression, yet the gene regulatory network underpinning oocyte growth remains elusive. Here we identified a set of transcription factors sufficient to trigger oocyte growth. By dissection of the change in gene expression and functional screening using an in vitro oocyte development system, we identified 8 transcription factors, each of which was essential for the primordial-primary follicle transition. Surprisingly, enforced expression of these transcription factors swiftly converted pluripotent stem cells to oocyte-like cells that were competent for fertilization and subsequent cleavage. These transcription factor-induced oocyte-like cells were formed without PGC specification, epigenetic reprogramming or meiosis, establishing that oocyte growth and lineage-specific de novo DNA methylation is separable from the preceding epigenetic reprogramming in PGCs. This study identifies a core set of transcription factors for orchestrating oocyte growth, and also provides an alternative source of ooplasm, which is a unique material for reproductive biology and medicine.
Project description:Using WGBS we investigated blood DNA methylation profiles of Cooinda the Alpine dingo and determined putative regulatory elements (unmethylated regions, UMRs, and lowly methylated regions, LMRs).
Project description:Somatic cells surrounding the oocyte were sampled at the following stages: developmentally incompetent or poorly competent prophase I oocytes (NC1 oocytes), developmentally competent prophase I oocytes (C1 oocytes), and developmentally competent metaphase II oocytes (C2 oocytes). NC1 samples were collected from late vitellogenic females (LV), C1 samples from post-vitellogenic females (PV), and C2 samples from females undergoing meiotic maturation (Germinal Vesicle Breakdown)