Syce1 and Syce3 regulate testosterone and dihydrotestosterone synthesis via steroidogenic pathways in mouse Sertoli and Leydig cells

Full-length transcriptome analysis of male and female gonads in Japanese Eel (Anguilla japonica)

BACKGROUND

The Japanese eel (Anguilla japonica) holds significant economic value in East Asia, but limitations in understanding its reproductive biology have hindered advancements in artificial breeding techniques. Previous research has primarily focused on conserved sex differentiation genes, offering limited insights into the broader molecular mechanisms driving gonadal development and sexual dimorphism. To address these limitations, this study aims to investigate key genes and pathways involved in gonadal development through a comprehensive transcriptomic analysis of male and female eel gonads.

RESULTS

PacBio Iso-Seq and Illumina RNA-Seq technologies were combined to conduct a full-length transcriptome analysis of male and female Japanese eel gonads at a post-differentiation, pre-maturation stage. A total of 24,661 unigenes were identified in ovaries and 15,023 in testes, along with genomic regulatory elements such as transcription factors, simple sequence repeats, and long non-coding RNAs. Additionally, 1,210 differentially expressed genes were detected. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed significant pathways involved in cell cycle regulation, metabolic processes, apoptosis, and hormone activity. Notably, several reproductive-related genes, including bambi, ccnb1, cdc20, gdf9, prlh, ccdc39, chrebp, tspo, syce3, and ngb, demonstrated significant dimorphic expression in eel gonads.

CONCLUSIONS

This study provides valuable insights into the molecular mechanisms of gonadal differentiation and sexual dimorphism in Japanese eels. The findings expand the genetic resources available for the eel breeding industry and could facilitate the development of improved artificial breeding techniques focused on reproductive development.

Whole-genome de novo sequencing reveals genomic variants associated with differences of sex development in SRY negative pigs

BACKGROUND

Differences of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. In more than 50% of human DSD cases, a molecular diagnosis is not available. In intensively farmed pig populations, the incidence of XX DSD pigs is relatively high, leading to economic losses for pig breeders. Interestingly, in the majority of 38, XX DSD pigs, gonads still develop into testis-like structures or ovotestes despite the absence of the testis-determining gene (SRY). However, the current understanding of the molecular background of XX DSD pigs remains limited.

METHODS

Anatomical and histological characteristics of XX DSD pigs were analysed using necropsy and HE staining. We employed whole-genome sequencing (WGS) with 10× Genomics technology and used de novo assembly methodology to study normal female and XX DSD pigs. Finally, the identified variants were validated in 32 XX DSD pigs, and the expression levels of the candidate variants in the gonads of XX DSD pigs were further examined.

RESULTS

XX DSD pigs are characterised by the intersex reproductive organs and the absence of germ cells in the seminiferous tubules of the gonads. We identified 4,950 single-nucleotide polymorphisms (SNPs) from non-synonymous mutations in XX DSD pigs. Cohort validation results highlighted two specific SNPs, "c.218T > C" in the "Interferon-induced transmembrane protein 1 gene (IFITM1)" and "c.1043C > G" in the "Newborn ovary homeobox gene (NOBOX)", which were found exclusively in XX DSD pigs. Moreover, we verified 14 candidate structural variants (SVs) from 1,474 SVs, identifying a 70 bp deletion fragment in intron 5 of the WW domain-containing oxidoreductase gene (WWOX) in 62.5% of XX DSD pigs. The expression levels of these three candidate genes in the gonads of XX DSD pigs were significantly different from those of normal female pigs.

CONCLUSION

The nucleotide changes of IFITM1 (c.218T > C), NOBOX (c.1043 C > G), and a 70 bp deletion fragment of the WWOX were the most dominant variants among XX DSD pigs. This study provides a theoretical basis for better understanding the molecular background of XX DSD pigs. DSD are conditions affecting development of the gonads or genitalia. These disorders can happen in many different types of animals, including pigs, goats, dogs, and people. In people, DSD happens in about 0.02-0.13% of births, and in pigs, the rate is between 0.08% and 0.75%. Pigs have a common type of DSD where the animal has female chromosomes (38, XX) but no SRY gene, which is usually found on the Y chromosome in males. XX DSD pigs may look like both males and females on the outside and have testis-like or ovotestis (a mix of ovary and testis) gonads inside. XX DSD pigs often lead to not being able to have piglets, slower growth, lower chance of survival, and poorer meat quality. Here, we used a method called whole-genome de novo sequencing to look for variants in the DNA of XX DSD pigs. We then checked these differences in a larger group of pigs. Our results reveal the nucleotide changes in IFITM1 (c.218T > C), NOBOX (c.1043 C > G), and a 70 bp deletion fragment in intron 5 of the WWOX, all linked to XX DSD pigs. The expression levels of these three genes were also different in the gonads of XX DSD pigs compared to normal female pigs. These variants are expected to serve as valuable molecular markers for XX DSD pigs. Because pigs are a lot like humans in their genes, physiology, and body structure, this research could help us learn more about what causes DSD in people.

An integrated approach for improving clinical management of non-obstructive azoospermia

BACKGROUND

Non-obstructive azoospermia is the most severe form of male infertility. A testicular biopsy is required for the diagnosis of non-obstructive azoospermia, and the causal factors for non-obstructive azoospermia remain unknown.

OBJECTIVES

To reduce the risk of multiple biopsies and identify factors that contribute to non-obstructive azoospermia, we proposed an integrated approach for the preoperative diagnosis and clinical management of non-obstructive azoospermia by applying the chromosome-spreading technique and whole-exome sequencing.

MATERIALS AND METHODS

Between July 2020 and December 2022, after ruling out definitive obstructive azoospermia and non-obstructive azoospermia patients with testicular volume < 6 mL, 20 patients with non-obstructive azoospermia who underwent preoperative testicular diagnostic biopsy using testicular sperm aspiration were subjected to retrospective analysis.

RESULTS

Microscopic examination identified four patients with sperm cells, and 16 without sperm cells. Routine pathological analysis classified one patient as normal spermatogenesis, three as hypospermatogenesis, five as maturation arrest, nine as Sertoli cell-only, and two as unable to judge. With chromosome-spreading technology using routine cell suspension samples for microscopic examination, 18 patient diagnoses were validated, and two patients without a definitive diagnosis were supplemented. Detection of the Y chromosome and a well-organized whole-exome sequencing analysis revealed potential genetic factors.

DISCUSSION AND CONCLUSION

The full use of testicular biopsy is beneficial for the diagnosis of azoospermia, as it avoids the risk of multiple biopsies. Moreover, in combination with whole-exome sequencing, clinicians can obtain more information regarding the pathogenesis of non-obstructive azoospermia, which may guide treatment.

Phthalates (PAEs) and reproductive toxicity: Hypothalamic-pituitary-gonadal (HPG) axis aspects

Phthalates (PAEs) are widely used for their excellent ability to improve plastic products. As an essential endocrine axis that regulates the reproductive system, whether dysfunction of the hypothalamic-pituitary-gonadal (HPG) axis is involved in reproductive toxicity mediated by environmental endocrine disruptors PAEs has become a hot topic of widespread concern. This study systematically reviewed the adverse effects of multiple PAEs on the HPG axis in different models and objectively discussed the possible underlying mechanisms. The abnormal release of gonadotropin-releasing hormone and gonadotropin, dysfunction of sex hormone receptors and steroid hormone synthesis, and general damage, including cell proliferation, oxidative stress, apoptosis, and autophagy have been confirmed to be involved in this process. Although it is widely established that PAEs induce HPG axis dysfunction, the specific mechanisms involved remain unclear. From a systematic review of relevant publications, it appears that the abnormal expression of peroxisome proliferator-activated, aryl hydrocarbon, and insulin receptors mediated by PAEs is key upstream event that induces these adverse outcomes; however, this inference needs to be further verified. Overall, this study aimed to provide reliable potential biomarkers for future environmental risk assessment and epidemiological investigation of PAEs.

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

Reproductive suppression is an adaptive strategy in animal reproduction. The mechanism of reproductive suppression has been studied in social animals, providing an essential basis for understanding the maintenance and development of population stability. However, little is known about it in solitary animals. The plateau zokor is a dominant, subterranean, solitary rodent in the Qinghai-Tibet Plateau. However, the mechanism of reproductive suppression in this animal is unknown. We perform morphological, hormonal, and transcriptomic assays on the testes of male plateau zokors in breeders, in non-breeders, and in the non-breeding season. We found that the testes of non-breeders are smaller in weight and have lower serum testosterone levels than those of breeders, and the mRNA expression levels of the anti-Müllerian hormone (AMH) and its transcription factors are significantly higher in non-breeder testes. Genes related to spermatogenesis are significantly downregulated in both meiotic and post-meiotic stages in non-breeders. Genes related to the meiotic cell cycle, spermatogenesis, flagellated sperm motility, fertilization, and sperm capacitation are significantly downregulated in non-breeders. Our data suggest that high levels of AMH may lead to low levels of testosterone, resulting in delayed testicular development, and physiological reproductive suppression in plateau zokor. This study enriches our understanding of reproductive suppression in solitary mammals and provides a basis for the optimization of managing this species.