GH Overexpression Alters Spermatic Cells MicroRNAome Profile in Transgenic Zebrafish

Identification of potential candidate miRNAs related to semen quality in seminal plasma extracellular vesicles and sperms of male duck (Anas Platyrhynchos)

Semen quality is an important indicator that can directly affect fertility. In mammals, miRNAs in seminal plasma extracellular vesicles (SPEVs) and sperms can regulate semen quality. However, relevant regulatory mechanism in duck sperms remains largely unclear. In this study, duck SPEVs were isolated and characterized by transmission electron microscopy (TEM), western blot (WB), and nanoparticle tracking analysis (NTA). To identify the important molecules affecting semen quality, we analysed the miRNA expression in sperms and SPEVs of male ducks in high semen quality group ((DHS, DHSE) and low semen quality group (DLS, DLSE). We identified 94 differentially expressed (DE) miRNAs in the comparison of DHS vs. DLS, and 21 DE miRNAs in DHSE vs. DLSE. Target genes of SPEVs DE miRNAs were enriched in ErbB signaling pathway, glycometabolism, and ECM-receptor interaction pathways (P < 0.05), while the target genes of sperm DE miRNAs were enriched in ribosome (P < 0.05). The miRNA-target-pathway interaction network analyses indicated that 5 DE miRNAs (miR-34c-5p, miR-34b-3p, miR-449a, miR-31-5p, and miR-128-1-5p) targeted the largest number of target genes enriched in MAPK, Wnt and calcium signaling pathways, of which FZD9 and ANAPC11 were involved in multiple biological processes related to sperm functions, indicating their regulatory effects on sperm quality. The comparison of DE miRNAs of SPEVs and sperms found that mir-31-5p and novel-273 could potentially serve as biomarkers for semen quality detection. Our findings enhance the insight into the crucial role of SPEV and sperm miRNAs in regulating semen quality and provide a new perspective for subsequent studies.

Deciphering sex-specific miRNAs as heat-recorders in zebrafish

In the last decade, a plethora of microRNAs (miRNAs) has been reported in a wide variety of physiological processes, including reproduction, in many aquatic organisms. However, miRNAome alterations occurred by environmental cues due to water temperature increment have not yet been elucidated. With the aim to identify epigenetic regulations mediated by miRNAs in the gonads in a climate change scenario, the animal model zebrafish (Danio rerio) were subjected to high temperatures during sex differentiation, a treatment that results in male-skewed sex ratios in the adulthood. Once the fish reached adulthood, gonads were sequenced by high-throughput technologies and a total of 23 and 1 differentially expressed miRNAs in ovaries and testes, respectively, were identified two months after the heat treatment. Most of these heat-recorder miRNAs were involved in human sex-related cancer and about 400 predicted-target genes were obtained, some with reproduction-related functions. Their synteny in the zebrafish genome was, for more than half of the predicted target genes, in the chromosomes 7, 2, 4, 3 and 11 in the ovaries, chromosome 4 being the place where the sex-associated-region (sar) is localized in wild zebrafish. Further, spatial localization in the gonads of two selected heat-recorder miRNAs (miR-122-5p and miR-146-5p) showed exclusive expression in the ovarian germ cells. The present study expands the catalog of sex-specific miRNAs and deciphers, for the first time, thermosensitive miRNAs in the zebrafish gonads that might be used as potential epimarkers to predict environmental past events.