Epigenetic regulator Cfp1 safeguards male meiotic progression by regulating meiotic gene expression

A candidate sex determination locus in amphibians which evolved by structural variation between X- and Y-chromosomes

Most vertebrates develop distinct females and males, where sex is determined by repeatedly evolved environmental or genetic triggers. Undifferentiated sex chromosomes and large genomes have caused major knowledge gaps in amphibians. Only a single master sex-determining gene, the dmrt1-paralogue (dm-w) of female-heterogametic clawed frogs (Xenopus; ZW♀/ZZ♂), is known across >8740 species of amphibians. In this study, by combining chromosome-scale female and male genomes of a non-model amphibian, the European green toad, Bufo(tes) viridis, with ddRAD- and whole genome pool-sequencing, we reveal a candidate master locus, governing a male-heterogametic system (XX♀/XY♂). Targeted sequencing across multiple taxa uncovered structural X/Y-variation in the 5'-regulatory region of the gene bod1l, where a Y-specific non-coding RNA (ncRNA-Y), only expressed in males, suggests that this locus initiates sex-specific differentiation. Developmental transcriptomes and RNA in-situ hybridization show timely and spatially relevant sex-specific ncRNA-Y and bod1l-gene expression in primordial gonads. This coincided with differential H3K4me-methylation in pre-granulosa/pre-Sertoli cells, pointing to a specific mechanism of amphibian sex determination.

A novel regulatory sex-skewing method that inhibits testicular DPY30 expression to increase female rate of dairy goat offspring

The demand for goat milk products has increased exponentially with the growth of the global population. The shortage of dairy products will be addressed extraordinarily by manipulating the female rate of goat offspring to expand the goat population and goat milk yield. No studies have reported bioinformatic analyses of X- and Y-bearing sperm of dairy goats, although this will contribute to exploring novel and applied sex-skewing technologies. Regulatory subunit of the histone methyltransferase complex (DPY30) was determined to be the key differentially expressed protein (DEP) among 15 DEPs identified in the present study. The spatiotemporal expression of DPY30 strongly suggested a functional involvement of the protein in spermatogenesis. DPY30 promoted meiosis via upregulating SYCP3, which played a crucial role in mediating sex ratio skewing in goats. Although DPY30 suppressed the self-renewal of spermatogonia stem cells through AKT/PLZF, DPY30 inhibition in the testis did not induce testicular dysgenesis. Based on the biosafety assessment in mice testes, lentivirus-mediated DPY30 knockdown in bucks' testes increased X-bearing sperm proportion and female kids' rate (22.8 percentage points) without affecting sperm quality, pregnancy rate, and kidding rate. This study provides the first evidence of the DEGs in the sexed sperm of dairy goats. DPY30 inhibition in the testes of bucks increased the female kids' rate without influencing reproductive performance. The present study provides evidence for expanding the female dairy goat population to address the concern of dairy product shortage.

Epigenetic regulation during meiosis and crossover

Meiosis is a distinctive type of cell division that reorganizes genetic material between generations. The initial stages of meiosis consist of several crucial steps which include double strand break, homologous chromosome pairing, break repair and crossover. Crossover frequency varies depending on the position on the chromosome, higher at euchromatin region and rare at heterochromatin, centromeres, telomeres and ribosomal DNA. Crossover positioning is dependent on various factors, especially epigenetic modifications. DNA methylation, histone post-translational modifications, histone variants and non-coding RNAs are most probably playing an important role in positioning of crossovers on a chromosomal level as well as hotspot level. DNA methylation negatively regulates crossover frequency and its effect is visible in centromeres, pericentromeres and heterochromatin regions. Pericentromeric chromatin and heterochromatin mark studies have been a centre of attraction in meiosis. Crossover hotspots are associated with euchromatin regions having specific chromatin modifications such as H3K4me3, H2A.Z. and H3 acetylation. This review will provide the current understanding of the epigenetic role in plants during meiotic recombination, chromosome synapsis, double strand break and hotspots with special attention to euchromatin and heterochromatin marks. Further, the role of epigenetic modifications in regulating meiosis and crossover in other organisms is also discussed.

Epigenetic markers in the embryonal germ cell development and spermatogenesis

Spermatogenesis is the process of generation of male reproductive cells from spermatogonial stem cells in the seminiferous epithelium of the testis. During spermatogenesis, key spermatogenic events such as stem cell self-renewal and commitment to meiosis, meiotic recombination, meiotic sex chromosome inactivation, followed by cellular and chromatin remodeling of elongating spermatids occur, leading to sperm cell production. All the mentioned events are at least partially controlled by the epigenetic modifications of DNA and histones. Additionally, during embryonal development in primordial germ cells, global epigenetic reprogramming of DNA occurs. In this review, we summarized the most important epigenetic modifications in the particular stages of germ cell development, in DNA and histone proteins, starting from primordial germ cells, during embryonal development, and ending with histone-to-protamine transition during spermiogenesis.