Bahlibi Weldegebriall Sahlu

Spermatogenesis is a complex, tightly regulated biological process crucial for male fertility in mammals. MicroRNAs (miRNAs) and messenger RNAs (mRNAs) play essential functions in regulating gene expression during spermatogenesis, and their specific roles in Holstein bull testicular development remain unclear. The study analyzed testicular tissues from young and mature Holstein bulls, unveiling the post-sexual maturation transcriptome landscape with a focus on spermatogenesis-associated miRNAs and mRNA profiles. The cDNA libraries from the testicular tissues of three young Holstein bulls (X1, X2, and X3; group YB) and three mature Holstein bulls (D5, D6, and D7; group AB) were established for RNA-sequencing analysis using Illumina high-throughput sequencing technology, followed by bioinformatics analysis. A total of 1114 miRNAs were identified in the X vs. D groups: 683 known miRNAs and 431 novel miRNAs. Notably, 221 known miRNAs exhibit differential expression between the X and D groups, with 118 up-regulated and 103 down-regulated genes. Moreover, a total of 237 previously unidentified novel miRNAs were also observed to exhibit differential expression between X and D, with 77 up-regulated and 160 down-regulated miRNA genes. These miRNA genes were linked to Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to male reproduction and spermatogenesis. The DE analysis of miRNA genes identified the top five up-regulated miRNAs (bta-miR-127, bta-miR-495, bta-miR-493, bta-miR-432, and bta-miR-3956) and down-regulated miRNAs (bta-miR-34c, bta-miR-34b, bta-miR-449a, bta-miR-449b, and 23_28233-5p (hsa-miR-6774-3p)) between the young bull and adult bull groups. The miRNA-mRNA network analysis also identified 17_16057-5p, X_45311-3p (cpo-miR-12072-3p), bta-miR-34c, bta-miR-375, 17_15431-5p (eca-miR-8912), 10_2547-3p (isc-miR-5313), bta-miR-449b, and mRNA genes such as BCL2L11, ADAMTSI1, MED1, and PRDM1; these genes were associated with reproductive system development. The mRNA genes (STRB and BCL2L11) and miRNA genes (bta-miR-134, bta-let-7e, bta-miR-181b, and bta-miR-214) were also found to have a significant correlation with the spermatogenic process. Thus, the comprehensive analysis of miRNA and mRNA enhances our knowledge of the regulatory networks involved in testicular development and identifies potential targets for further investigation and manipulation to improve cattle reproductive efficiency and genetic selection.

Long noncoding RNAs (lncRNAs) are composed of nucleotides located in the nucleus and cytoplasm; these are transcribed by RNA polymerase II and are greater than 200 nt in length. LncRNAs fulfill important functions in a variety of biological processes, including genome imprinting, cell differentiation, apoptosis, stem cell pluripotency, X chromosome inactivation and nuclear transport. As high throughput sequencing technology develops, a substantial number of lncRNAs have been found to be related to a variety of biological processes, such as development of the testes, maintaining the self-renewal and differentiation of spermatogonial stem cells, and regulating spermatocyte meiosis. These indicate that lncRNAs can be used as biomarkers and potential therapeutic targets for male infertility. However, only a few comprehensive reviews have described the role of lncRNAs in male reproduction. In this paper, we summarize recent findings relating to the role of lncRNAs in spermatogenesis, their potential as biomarkers for male infertility and the relationship between reproductive arrest and transgenerational effects. Finally, we suggest specific targets for the treatment of male infertility from the perspective of lncRNAs.

Homozygosity of long sequence genotypes are a result of parents transmitting identical haplotypes, which can be used to estimate their auto-zygosity. Therefore, we used high-density SNP Chip data to characterize the auto-zygosity of each breed according to the occurrence and distribution of runs of homozygosity (ROH). Subsequently, we identified the genomic regions with high runs of homozygosity frequencies within individuals of each breed. We selected 96 sheep samples from five local Chinese sheep breeds belonging to different geographical locations. We identified 3046 ROHs within the study breed individuals, among which the longer segments (>1–5 Mb) were dominant. On average, ROH segments covered about 12% of the genomes; the coverage rate of OAR20 was the lowest and that of OAR2 was the highest. The distribution analysis of runs of homozygosity showed that the detected ROH mainly distributed between >26 and 28 Mb. The Hetian and Hu sheep showed the lowest ROH distribution. The estimation of homozygosity level reflects the history of modern and ancient inbreeding, which may affect the genomes of Chinese indigenous sheep breeds and indicate that some animals have experienced recent self-pollination events (Yabuyi, Karakul and Wadi). In these sheep breeds, the genomic regions were assumed to be under selection signatures frequently in line with long ROH. These regions included candidate genes associated with disease resistance traits (5S_rRNA), the innate and adaptive immune response (HERC2 and CYFIP1), digestion and metabolism (CENPJ), growth (SPP1), body size and developments (GJB2 and GJA3). This study highlighted new insights into the ROH patterns and provides a basis for future breeding and conservation strategies of Chinese sheep breeds.

Anti-Mullerian hormone (AMH) is an important reproductive marker of ovarian reserve produced by granulosa cells (GCs) of pre-antral and early-antral ovarian follicles in several species, including cattle. This hormone plays a vital role during the recruitment of primordial follicles and follicle stimulating hormone (FSH)-dependent follicular growth. However, the regulatory mechanism of AMH expression in follicles is still unclear. In this study, we compared the expression of AMH, AMHR-II, BMP2, BMP6, FSHR, and LHCGR genes during follicular development. In-vitro expression study was performed with and without FSH for AMH, AMHR-II, BMP2, and BMP6 genes in bovine GCs which were isolated from 3–8 mm follicles. Association among the mRNA expression and hormone level was estimated. GCs were collected from small (3–8 mm), medium (9–12 mm) and large size (13 to 24 mm) follicles before, during onset, and after deviation, respectively. Further, mRNA expression, hormones (AMH, FSH, and LH), apoptosis of GCs, and cell viability were detected by qRT-PCR, ELISA, flow cytometry, and spectrophotometry. AMH, AMHR-II, BMP2, and FSHR genes were highly expressed in small and medium follicles as compared to large ones. In addition, the highest level of AMH protein (84.14 ± 5.41 ng/mL) was found in medium-size follicles. Lower doses of FSH increased the viability of bovine GCs while higher doses repressed them. In-vitro cultured GCs treated with FSH significantly increased the AMH, AMHR-II, and BMP2 expression levels at lower doses, while expression levels decreased at higher doses. We found an optimum level of FSH (25 ng/mL) which can significantly enhance AMH and BMP2 abundance (p < 0.05). In summary, AMH, AMHR-II, and BMP2 genes showed a higher expression in follicles developed in the presence of FSH. However, lower doses of FSH demonstrated a stimulatory effect on AMH and BMP2 expression, while expression started to decline at the maximum dose. In this study, we have provided a better understanding of the mechanisms regulating AMH, AMHR II, and BMP2 signaling in GCs during folliculogenesis, which would improve the outcomes of conventional assisted reproductive technologies (ARTs), such as superovulation and oestrus synchronization in bovines.

Anti-Müllerian hormone (AMH) is a reliable and easily detectable reproductive marker for the fertility competence of many farm animal species. AMH is also a good predictor of superovulation in cattle, sheep, and mares. In this review, we have summarized the recent findings related to AMH and its predictive reliability related to fertility and superovulation in domestic animals, especially in cattle. We focused on: (1) the dynamics of AMH level from infancy to prepubescence as well as during puberty and adulthood; (2) AMH as a predictor of fertility; (3) the association between antral follicle count (AFC) and plasma AMH level; (4) AMH as a predictor of superovulation; and (5) factors affecting AMH levels in domestic animals, especially cattle. Many factors affect the circulatory levels of AMH when considering the plasma, like nutrition, activity of granulosa cells, disease state and endocrine disruptions during fetal life. Briefly, we concluded that AMH concentrations are static within individuals, and collection of a single dose of blood has become more popular in the field of assisted reproductive technologies (ART). It may act as a potential predictor of fertility, superovulation, and ovarian disorders in domestic animals. However, due to the limited research in domestic animals, this potential of AMH remains underutilized.