Genes involved in spermatogenesis: Genes involved in spermatogenesis

Single-Cell RNA Sequencing of the Testis of Ciona intestinalis Reveals the Dynamic Transcriptional Profile of Spermatogenesis in Protochordates

Spermatogenesis is a complex and continuous process of germ-cell differentiation. This complex process is regulated by many factors, of which gene regulation in spermatogenic cells plays a decisive role. Spermatogenesis has been widely studied in vertebrates, but little is known about spermatogenesis in protochordates. Here, for the first time, we performed single-cell RNA sequencing (scRNA-seq) on 6832 germ cells from the testis of adult Ciona intestinalis. We identified six germ cell populations and revealed dynamic gene expression as well as transcriptional regulation during spermatogenesis. In particular, we identified four spermatocyte subtypes and key genes involved in meiosis in C. intestinalis. There were remarkable similarities and differences in gene expression during spermatogenesis between C. intestinalis and two other vertebrates (Chinese tongue sole and human). We identified many spermatogenic-cell-specific genes with functions that need to be verified. These findings will help to further improve research on spermatogenesis in chordates.

Silica nanoparticles cause spermatogenesis dysfunction in mice via inducing cell cycle arrest and apoptosis

The widespread use of silica nanoparticles (SiNPs) has increased the risk of human exposure, which raised concerns about their adverse effects on human health, especially the reproductive system. Previous studies have shown that SiNPs could cause damage to reproductive organs, but the specific mechanism is still unclear. In this study, to investigate the underlying mechanism of male reproductive toxicity induced by SiNPs, 40 male mice at the age of 8 weeks were divided into two groups and then intraperitoneally injected with vehicle control or 10 mg/kg SiNPs per day for one week. The results showed that SiNPs could damage testicular structure, perturb spermatogenesis and reduce serum testosterone levels, leading to a decrease in sperm quality and quantity. In addition, the ROS level in the testis of exposed mice was significantly increased, followed by imbalance of the oxidative redox status. Further study revealed that exposure to SiNPs led to cell cycle arrest and apoptosis, as shown by downregulation of the expression of positive cell cycle regulators and the activation of TNF-α/TNFR Ⅰ-mediated apoptotic pathway. The results demonstrated that SiNPs could cause testicles injure via inducing oxidative stress and DNA damage which led to cell cycle arrest and apoptosis, and thereby resulting in spermatogenic dysfunction.

Silica nanoparticles induce start inhibition of meiosis and cell cycle arrest via down-regulating meiotic relevant factors

Silica nanoparticles have been shown to induce reproductive toxicity, but the mechanism is unknown. To investigate the toxic mechanism of SiNPs, 60 male mice were randomly divided into three groups: a control group, a saline group and a SiNPs group, with two evaluation time points (45 and 75 days after the first dose) per group. Mice in the SiNPs group were treated with SiNPs at a dose of 2.0 mg kg-1 every three days, a total of 15 times in 45 days, mice in the saline group were given the same volume of physiological saline, and the control group was treated with nothing. Then, half of the mice in each group were sacrificed for tissue samples on days 45 and 75. In vitro, GC-2spd cells were exposed to various concentrations of SiNPs for 24 h. The results showed that SiNPs damaged seminiferous epithelium, leading to a decrease in sperm quality and an increase in the sperm abnormality rate. Moreover, expressions of Sohlh1/cyclin A1/cyclin B1/CDK1/CDK2 were greatly down-regulated and the ROS level in the testicular tissue of the mice was significantly increased on day 45. However, these changes were reversed by day 75. In vitro, SiNPs induced G0/G1-phase cell cycle arrest and proliferation inhibition in GC-2spd cells. These results suggested that SiNPs might induce cell cycle arrest and inhibit cell proliferation by down-regulating expressions of meiotic regulators, whereas DNA damage caused by oxidative stress may be associated with meiosis and sperm production. In addition, damage to the male reproductive system caused by SiNPs may be reversible.

Aneuploidies level in sperm nuclei in patients with infertility

Male infertility is a relevant social and medical problem. Male infertility is mostly caused by genetic disorders. The purpose of the study was to analyze the correlation of chromosome aberrations, as well as DNA fragmentation and various manifestations of spermatogenesis disorder. Sperm samples of 58 males with infertility and 23 conditionally healthy males were studied. All patients diagnosed with asthenozoospermia, teratozoospermia, oligoasthenozoospermia and oligoteratozoospermia underwent subsequent analysis of sperm DNA fragmentation. Sperm DNA fragmentation was examined with sperm chromatin dispersion test (sperm chromatin dispersion, Spermprocessor, India) with an Axioscope 40 fluorescent microscope. Fluorescence in situ hybridization with fluorescent probes (Vysis Multi Vysion PGT, Abbot Molecular) was used to study chromosome abnormalities in sperm nuclei with regard to X and Y chromosomes, as well as to chromosomes 18 and 21. It was found that the development of pathospermia was characterized by genetic discontinuity, which manifests as DNA fragmentation and disjunction of chromosomes in meiosis with spermatogenesis. It was also found that the prevailing type of pathospermia in men with infertility was oligozoospermia. In addition, this group also had the highest rate of numerical chromosome abnormalities. This was caused by the degeneration of spermatozoids with aneuploidies in chromosomes.

Transition of basic protein during spermatogenesis of Fenneropenaeus chinensis (Osbeck, 1765)

According to the ultrastructural characteristic observation of the developing male germ cells, spermatogenesis of the crustacean shrimp, Fenneropenaeus chinensis, is classified into spermatogonia, primary spermatocytes, secondary spermatocyte, four stages of spermatids, and mature sperm. The basic protein transition during its spermatogenesis is studied by transmission electron microscopy of ammoniacal silver reaction and immunoelectron microscopical distribution of acetylated histone H4. The results show that basic protein synthesized in cytoplasm of spermatogonia is transferred into the nucleus with deposition on new duplicated DNA. In the spermatocyte stage, some nuclear basic protein combined with RNP is transferred into the cytoplasm and is involved in forming the cytoplasmic vesicle clumps. In the early spermatid, most of the basic protein synthesized in the new spermatid cytoplasm is transferred into the nucleus, and the chromatin condensed gradually, and the rest is shifted into the pre-acrosomal vacuole. In the middle spermatid, the nuclear basic protein linked with DNA is acetylated and transferred into the proacrosomal vacuole and assembled into the acrosomal blastema. At the late spermatid, almost all of the basic protein in the nucleus has been removed into the acrosome. During the stage from late spermatid to mature sperm, some de novo basic proteins synthesized in the cytoplasm belt transfer into the nucleus without a membrane and almost all deposit in the periphery to form a supercoating. The remnant histone H4 accompanied by chromatin fibers is acetylated in the center of the nucleus, leading to relaxed DNA and activated genes making the nucleus non-condensed.

[Research on modular organization of gene regulatory network]

Gene regulatory network is very important for researchers to understand biological processes and gene functions. It can deliver complex information about how could large amount of genes be regulated by transcriptional factors and translated into proteins which can carried out biological functions. Generally, knowledge of network topological structure and organization formation can be used to find the regulatory mechanism of genes in the regulatory network. It can illuminate the local characters of the network and reveal the constructing methods of regulatory network; moreover, it can also analyze regulatory pathway completely and systemically. Now, more and more researchers approbate the hierarchy structure of gene regulatory network: regulatory component, Motif, module and the whole network. Here, we discuss the middle two levels: motif and module. We compared various research results of network organization carried out in recent years, explicated their biology signification and pointed out the existing disadvantages and problems. According these problems, we also bring up some possible research trend. And at last, we discuss the prospect of gene regulatory network modular organization researching work.