Reproductive Suppression Caused by Spermatogenic Arrest: Transcriptomic Evidence from a Non-Social Animal

The DNA methylation status of the vitamin A signaling associated with testicular degeneration induced by long-day photoperiods in Magang geese

Magang geese are typical short-day breeders whose reproductive behaviors are significantly influenced by photoperiod. Exposure to a long-day photoperiod results in testicular regression and spermatogenesis arrest in Magang geese. To investigate the epigenetic influence of DNA methylation on the seasonal testicular regression in Magang geese, we conducted whole-genome bisulfite sequencing and transcriptome sequencing of testes across 3 reproductive phases during a long-day photoperiod. A total of 250,326 differentially methylated regions (DMR) were identified among the 3 comparison groups, with a significant number showing hypermethylation, especially in intronic regions of the genome. Integrating bisulfite sequencing with transcriptome sequencing data revealed that DMR-associated genes tend to be differentially expressed in the testes, highlighting a potential regulatory role for DNA methylation in gene expression. Furthermore, there was a significant negative correlation between changes in the methylation of CG DMRs and changes in the expression of their associated genes in the testes. A total of 3,359 DMR-associated differentially expressed genes (DEG) were identified; functional enrichment analyses revealed that motor proteins, MAPK signaling pathway, ECM-receptor interaction, phagosome, TGF-beta signaling pathway, and calcium signaling might contribute to the testicular regression process. GSEA revealed that the significantly enriched activated hallmark gene set was associated with apoptosis and estrogen response during testicular regression, while the repressed hallmark gene set was involved in spermatogenesis. Our study also revealed that methylation changes significantly impacted the expression level of vitamin A metabolism-related genes during testicular degeneration, with hypermethylation of STRA6 and increased calmodulin levels indicating vitamin A efflux during the testicular regression. These findings were corroborated by pyrosequencing and real-time qPCR, which revealed that the vitamin A metabolic pathway plays a pivotal role in testicular degeneration under long-day conditions. Additionally, metabolomics analysis revealed an insufficiency of vitamin A and an abnormally high level of oxysterols accumulated in the testes during testicular regression. In conclusion, our study demonstrated that testicular degeneration in Magang geese induced by a long-day photoperiod is linked to vitamin A homeostasis disruption, which manifests as the hypermethylation status of STRA6, vitamin A efflux, and a high level of oxysterol accumulation. These findings offer new insights into the effects of DNA methylation on the seasonal testicular regression that occurs during long-day photoperiods in Magang geese.

Spermatocytes are the terminals of germ cell differentiation in plateau zokor (Eospalax baileyi) during the non-breeding season

Plateau zokor (Eospalax baileyi) is a subterranean rodent and seasonal breeder. During the non-breeding season, the testicles regress, leading to the arrest of spermatogenesis and loss of fertility. The identification of the specific germ cell type at which spermatogenesis is arrested, as well as potential regulatory factors during the non-breeding season, is important for understanding seasonal spermatogenesis in subterranean species. This study analyzed genes in spermatocytes of plateau zokor by referring to single-cell RNA results in mice. We discovered that spermatogenesis is arrested at the spermatocyte during the non-breeding season, which was corroborated via immunofluorescence staining results. The analysis of gene expression during different stages of meiotic prophase I has revealed that germ cell development may be arrested, starting from zygonema, during the non-breeding season. Meanwhile, we discovered that the apoptosis genes were up-regulated, leading to apoptosis in spermatocytes. To confirm that the germ cell differentiation was blocked during the non-breeding season due to a decrease in the androgen level, we used androgen receptor antagonist (flutamide) to intervene in the breeding season and found that the inner diameter of the seminiferous tubules was significantly reduced, spermatogenesis was arrested, and spermatocytes underwent apoptosis. This study revealed that spermatocytes are the terminal of germ cell differentiation in plateau zokor during the non-breeding season and that the arrest of differentiation is attributed to a decline in androgen levels. Our results complement the theoretical basis of seasonal reproduction in plateau zokor.

Two plants improve stress response of a subterranean herbivore by downregulating amphetamine addiction pathways

Introduction

Captivity serves as the primary method for enhancing animal survival and productivity. However, the stress induced by confinement can hinder animal growth and reproduction. The administration of drugs to captive animals can effectively regulate their stress response and can also be used inartificial breeding, reproduction, and experimental animalization of wild species. The plateau zokor (Eospalax baileyi), a subterranean herbivore, experiences significant stress during the captive process owing to its unique habitat.

Methods

In our study, we utilized Radix astragali (RA) and Acanthopanax senticosus (AS) extracts to intervene in the stress response of plateau zokors.

Results

Our findings demonstrated that RA and AS treatment considerably improved food intake and reduced weight loss, stress-related behavior, and stress hormone levels in plateau zokors. Furthermore, the excitatory pathway of amphetamine addition in the hypothalamus was suppressed by RA and AS treatment, acting through the Grin and Prkc gene families. Notably, after RA treatment, the extracellular matrix-receptor interaction pathway, enriched by the Col1a1/3a1/1a2/6a1 gene, was significantly upregulated, potentially enhancing the immune function of captive plateau zokors.

Discussion

In conclusion, our research demonstrates that RA and AS treatment can effectively alleviate the stress response of plateau zokors in captive environments. The downregulation of the excitation pathway and upregulation of the immune pathway offer valuable insights into the response and potential mechanisms of plant-based drugs in mitigating animal stress.

Seasonal patterns of miRNA and mRNA expression profiles in the testes of plateau zokors (Eospalax baileyi)

The gonads of seasonal breeding animals undergo periodic annual changes in morphology, physiological hormones, and gene expression levels. To clarify the regulatory mechanism of miRNAs in the seasonal testicular development and spermatogenesis of plateau zokors, the miRNA expression profiles in their testicles during breeding and non-breeding seasons were analyzed. In total, 447 miRNAs, including 366, 81, and 167 known, novel, and differentially expressed (DE) miRNAs, respectively, were determined in the testes. Compared to the non-breeding season, 90 DE miRNAs were upregulated and 77 DE miRNAs were downregulated during the breeding season. By analysing the miRNA and mRNA expression profiles, we predicted 2096 significant target mRNAs. According to the miRNA-mRNA interaction network, target mRNAs with DE miRNAs were related to testicular development and spermatogenesis. GO indicated that target mRNAs were enriched in spermatogenesis, cell differentiation, multicellular biological development, and flagellated sperm movement and were associated with regulating testicular development and spermatogenesis. KEGG suggested that target mRNAs were enriched in lipid and fructose metabolism and provided energy and material for spermatogenesis. The target mRNA of rno-miR-24-3p was determined to be Polyubiquitin-B (UBB). Our results provide a reference for revealing the mechanism by which miRNAs regulate testicular development and spermatogenesis in plateau zokors, which has important implications for understanding the regulation of seasonal reproduction in animals.

Comparative analysis of microRNA and messengerRNA expression profiles in plateau zokor testicular cells under reproductive suppression

Introduction

Reproductive suppression is an adaptive strategy that affects the success rate and reproductive efficiency in animals, which in turn affects population continuation and evolution. However, no studies on the miRNAs in testicular development and spermatogenesis regulatory mechanisms under reproductive suppression have been reported.

Methods

In this study, the differentially expressed (DE) miRNAs, miRNA-mRNA interaction network and function of the plateau zokor testicular cells of non-breeders and breeders during the breeding season were comprehensively analyzed by transcriptomics.

Results

In total, 381 known and 94 novel miRNAs were determined. Compared with that in the breeders, 70 downregulated and 68 upregulated DE miRNAs were identified in the non-breeders. We predicted 1670 significant target mRNAs by analyzing the miRNA and mRNA expression profiles. According to the miRNA-mRNA interaction network, the target mRNAs of the DE miRNAs were related to testicular development and spermatogenesis. GO indicate that the target mRNAs were related to testicular development and spermatogenesis. KEGG indicate that pathways of target mRNAs enrichment related to testicular development, spermatogenesis, and energy metabolism. PROK2 was determined as the target mRNA of rno-miR-143-3p.

Discussion

Our study offers a basis for the regulatory mechanisms of miRNAs in testicular development and spermatogenesis in plateau zokor under reproductive suppression and offers a reference for reproductive regulation.

Potential Role of Anti-Müllerian Hormone in Regulating Seasonal Reproduction in Animals: The Example of Males

Seasonal reproduction is a survival strategy by which animals adapt to environmental changes to improve their fitness. Males are often characterized by a significantly reduced testicular volume, indicating that they are in an immature state. Although many hormones, including gonadotropins, have played a role in testicular development and spermatogenesis, research on other hormones is insufficient. The anti-Müllerian hormone (AMH), which is a hormone responsible for inducing the regression of Müllerian ducts involved in male sex differentiation, was discovered in 1953. Disorders in AMH secretion are the main biomarkers of gonadal dysplasia, indicating that it may play a crucial role in reproduction regulation. A recent study has found that the AMH protein is expressed at a high level during the non-breeding period of seasonal reproduction in animals, implying that it may play a role in restricting breeding activities. In this review, we summarize the research progress on the AMH gene expression, regulatory factors of the gene's expression, and its role in reproductive regulation. Using males as an example, we combined testicular regression and the regulatory pathway of seasonal reproduction and attempted to identify the potential relationship between AMH and seasonal reproduction, to broaden the physiological function of AMH in reproductive suppression, and to provide new ideas for understanding the regulatory pathway of seasonal reproduction.