Prion protein testis specific (PRNT) gene polymorphisms and transcript level in ovine spermatozoa: Implications in freezability, fertilization and embryo production

Paternal Effects in Mammalian Reproduction: Functional, Environmental, and Clinical Relevance of Sperm Components in Early Embryos and Beyond

In addition to widely recognized contributions of the paternal genome, centriole, and oocyte-activation factors, sperm deliver a wide range of macromolecules to the fertilized embryo. The impacts of these factors on the embryo, progeny, and even subsequent generations have become increasingly apparent, along with an understanding of an extensive potential for male health and environmental exposures to exert both immediate and long-term impacts on mammalian reproduction. Available data reveal that sperm factors interact with and regulate the actions of oocyte factors as well as exerting additional direct effects on the early embryo. This review provides a summary of the nature and mechanisms of paternal effects in early mammalian embryos, long-term effects in progeny, susceptibility of sperm components to diverse environmental factors, and potential approaches to mitigate adverse effects of such exposures.

Effect of Urolithin A on Bovine Sperm Capacitation and In Vitro Fertilization

Reactive oxygen species (ROS) play a critical role in the functional competence of sperm cells. Conversely, excessive generation of ROS can impair sperm function, including their fertilization ability. Urolithin A (UA), a gut bacteria-derived metabolite produced from the transformation of ellagitannins, with anti-aging and antioxidant properties, was investigated for the first time in bovine sperm cells in the present study. Firstly, different doses of UA (0, 1, and 10 μM; 8-16 sessions) were used during the capacitation process of frozen-thawed bovine sperm. Sperm motility was assessed using optical microscopy and CASA. Sperm vitality (eosin-nigrosin), ROS, and ATP levels, as well as mitochondrial membrane potential (JC1) and oxygen consumption were evaluated. A second experiment to test the effect of different doses of UA (0, 1, and 10 μM; 9 sessions) in both the capacitation medium, as above, and the fertilization medium, was also implemented. The embryonic development and quality were evaluated. UA, at a concentration of 1 μM, significantly improved sperm movement quality (p < 0.03). There was a trend towards an increase in the oxygen consumption rate (OCR) of capacitated sperm with 1 μM and 10 μM UA supplementation. Moreover, an increase in ATP levels (p < 0.01) was observed, accompanied by a reduction in ROS levels at the higher UA concentration. These results suggest that UA may enhance spermatozoa mitochondrial function, modifying their metabolic activity while reducing the oxidative stress. Also, the number of produced embryos appears to be positively affected by UA supplementation, although differences between the bulls may have mitigated this effect. In conclusion, presented results further support previous findings indicating the potential therapeutic value of UA for addressing reproductive sub/infertility problems and improving ART outcomes. In addition, our results also reinforce the important bull effect on ART and that male sperm bioenergetic parameters should be used to predict spermatozoa functionality and developmental potential.

Physiology of Cellular Prion Proteins in Reproduction

Cellular prion protein (PrPC) encoded at Prnp gene is well-known to form a misfolded isoform, termed scrapie PrP (PrPSC) that cause transmissible degenerative diseases in central nervous system. The physiological role of PrPC has been proposed by many studies, showing that PrPC interacts with various intracellular, membrane, and extracellular molecules including mitochondrial inner membrane as a scaffold. PrPC is expressed in most cell types including reproductive organs. Numerous studies using PrPC knockout rodent models found no obvious phenotypic changes, in particular the clear phenotypes in development and reproduction have not demonstrated in these knockout models. However, various roles of PrPC have been evaluated at the cellular levels. In this review, we summarized the known roles of PrPC in various cell types and tissues with a special emphasis on those involved in reproduction.

Effect of a Novel Hydroxybenzoic Acid Based Mitochondria Directed Antioxidant Molecule on Bovine Sperm Function and Embryo Production

Sperm cells are particularly vulnerable to reactive oxygen species (ROS), impairing their fertilizing ability. Our objective was to study the effect of a novel mitochondrial-directed antioxidant, AntiOxBEN2, on bovine sperm function. This antioxidant was added to the semen capacitation medium (CAP), during the swim-up process, and to the fertilization medium (FERT) during the co-incubation of matured oocytes and capacitated spermatozoa, in concentrations of 0 (control), 1, and 10 µM. After the swim-up, sperm motility (CASA and visual analysis), vitality (eosin-nigrosin), mitochondrial membrane potential (JC1), intracellular ROS, adenosine triphosphate (ATP) levels, and basal metabolism (Seahorse Xfe96) were evaluated. Embryo development and quality were also assessed. Higher cleavage rates were obtained when 1 µM AntiOxBEN2 were added to CAP and FERT media (compared to control, p < 0.04). A positive effect of AntiOxBEN2 on intracellular ROS reduction (p = 0.01), on the increment of mitochondrial membrane potential (p ≤ 0.003) and, consequently, on the sperm quality was identified. However, the highest dose impaired progressive motility, ATP production, and the number of produced embryos. The results demonstrate a beneficial effect of AntiOxBEN2 (1 µM) on sperm capacitation and fertilization processes, thus improving embryonic development. This may constitute a putative novel therapeutic strategy to improve the outcomes of assisted reproductive techniques (ART).

Investigation of Genetic Effects of Nucleotide Variants Within the Goat PRNT Gene on Growth Performance

Our previous study has firstly pointed that three nucleotide variants (g.-11C > T, g.117A > G, and g.149C > T) of the goat PRNT gene can significantly influence litter size. Given litter size is positively correlated with growth performance, we consider whether the PRNT gene also acts on the growth performance in goats. In this work, a correlation analysis among different litter size types and growth traits of Shaanbei white cashmere (SBWC) goats was performed, and results showed that a positive correlation did exist in our detected population (P < 0.01). Then, the association among different genotypes of three variations and goat growth performance was measured. Our results pointed to g.117A > G being significantly associated with the cannon circumference (P = 4.60E-05) while no significant effect was found between another two SNPs and growth traits after the Bonferroni's correction (P*n < 0.05). Together, this is the first report about the influence of the PRNT gene on the growth of goat and g.117A > G can be regarded as a possible DNA marker applying for MAS breeding.

The mRNA expression profile of the goat prion protein testis-specific (PRNT) gene and its associations with litter size

The goat PRNT gene was initially identified as a testis-specific gene with a role in spermatogenesis. In this study, we used quantitative real-time PCR (qPCR) to first determine the mRNA expression profile of this gene in different goat tissues. Surprisingly, we found that PRNT was expressed not only in the testis but also in nine other tissues in goats. Moreover, PRNT was weakly expressed in the testis, while its expression was strongest in the ovary. These results, combined with those of other studies, led us to hypothesize that the goat PRNT gene has a role in both male and female reproduction. We further used direct DNA sequencing to detect potential SNPs within this gene in Shaanbei whit cashmere (SBWC) rams and ewes, and identified three SNPs within the PRNT gene, namely, c.-58C > T, c.71A > G (p.Alanine24Valine), and c.102C > T (synonymous). In rams, c.-58C > T and c.102C > T were strongly linked with each other (D' = 1.000, r² = 0.504), whereas no significant association (P > 0.05) was found between the three SNPs and semen quality, which was consistent with the low expression of the PRNT gene in the testis. Interestingly, in ewes (n = 502), c.-58C > T and c.71A > G were also strongly linked with each other (D' = 0.973, r² = 0.537). Additionally, the c.71A > G locus, especially the AA genotype, had a significant influence on litter size (P = 0.006), consistent with the high PRNT expression in the ovary. Combined, the results of the expression profiling and analysis of the association between the SNPs and reproductive traits showed that two strongly linked nucleotide sequence variants within PRNT were significantly associated with goat litter size. These findings provide potential DNA markers for use in the marker-assisted selection (MAS) of goats with high-fertility traits.

Sperm Cryodamage in Ruminants: Understanding the Molecular Changes Induced by the Cryopreservation Process to Optimize Sperm Quality

Sperm cryopreservation represents a powerful tool for livestock breeding. Several efforts have been made to improve the efficiency of sperm cryopreservation in different ruminant species. However, a significant amount of sperm still suffers considerable cryodamage, which may affect sperm quality and fertility. Recently, the use of different “omics” technologies in sperm cryobiology, especially proteomics studies, has led to a better understanding of the molecular modifications induced by sperm cryopreservation, facilitating the identification of different freezability biomarkers and certain proteins that can be added before cryopreservation to enhance sperm cryosurvival. This review provides an updated overview of the molecular mechanisms involved in sperm cryodamage, which are in part responsible for the structural, functional and fertility changes observed in frozen–thawed ruminant sperm. Moreover, the molecular basis of those factors that can affect the sperm freezing resilience of different ruminant species is also discussed as well as the molecular aspects of those novel strategies that have been developed to reduce sperm cryodamage, including new cryoprotectants, antioxidants, proteins, nanoparticles and vitrification.

Prion-like protein gene (PRND) polymorphisms associated with scrapie susceptibility in Korean native black goats

The polymorphisms of the prion protein (PRNP) gene, which encodes normal prion proteins (PrP), are known to be involved in the susceptibility of prion diseases. The prion-like protein (Doppel) gene (PRND) is the paralog of the PRNP gene and is closely located downstream of the PRNP gene. In addition, the polymorphisms of PRND correlate with disease susceptibility in several animals. We analyzed the genotype and allele frequencies of PRND polymorphisms in 246 Korean native black goats and found a total of six single nucleotide polymorphisms (SNPs) with one novel SNP, c.99C>T. We observed linkage disequilibrium (LD) within and between loci. PRND c.28T>C, c.151A>G, and c.385G>C and PRND c.65C>T and c.286G>A were in perfect LD and we have reported for the first time strong LD between PRND and PRNP or prion-related protein gene (PRNT) loci. Specifically, between the PRND c.28T>C, c.151A>G and c.385G>C and the PRNP codon 143, PRND c.99C>T and the PRNP codon 102 or PRND SNPs (c.28T>C, c.151A>G and c.385G>C) and PRNT SNP (c.321T>C). Furthermore, we confirmed that the genotype distribution of the PRNP p.His143Arg was significantly different according to that of the PRND c.28T>C (P < 0.0001). Finally, using PolyPhen-2 and PROVEAN, we predicted that two non-synonymous SNPs, c.65C>T and c.286G>A, in the PRND gene can have a detrimental effect on Doppel. To the best of our knowledge, this is the first report of genetic characteristics of the PRND gene in Korean native black goats.