Morphometric evaluation of seminiferous tubule and proportionate numerical analysis of Sertoli and spermatogenic cells indicate differences between crossbred and purebred bulls

LCRMP-1 is required for spermatogenesis and stabilises spermatid F-actin organization via the PI3K-Akt pathway

Long-form collapsin response mediator protein-1 (LCRMP-1) belongs to the CRMP family which comprises brain-enriched proteins responsible for axon guidance. However, its role in spermatogenesis remains unclear. Here we find that LCRMP-1 is abundantly expressed in the testis. To characterize its physiological function, we generate LCRMP-1-deficient mice (Lcrmp-1^-/-). These mice exhibit aberrant spermiation with apoptotic spermatids, oligospermia, and accumulation of immature testicular cells, contributing to reduced fertility. In the seminiferous epithelial cycle, LCRMP-1 expression pattern varies in a stage-dependent manner. LCRMP-1 is highly expressed in spermatids during spermatogenesis and especially localized to the spermiation machinery during spermiation. Mechanistically, LCRMP-1 deficiency causes disorganized F-actin due to unbalanced signaling of F-actin dynamics through upregulated PI3K-Akt-mTOR signaling. In conclusion, LCRMP-1 maintains spermatogenesis homeostasis by modulating cytoskeleton remodeling for spermatozoa release.

Genom-wide analysis identifies single nucleotide polymorphism variations and altered pathways associated with poor semen quality in breeding bulls

The reason for poor semen quality among the breeding bulls is not well understood. In the present study, we performed high-throughput RNAseq analysis of spermatozoa to identify the SNPs present in good and poor-quality semen-producing Holstein Friesian breeding bulls. A total of 21,360 and 44,650 SNPs were identified in good and poor-quality semen with a minimum read depth of 20, among which 4780 and 8710 novel variants were observed in good and poor-quality semen, respectively. Greater SNPs and indels variations were observed in poor compared to good-quality semen. In poor-quality semen, SNP variations were observed in ZNF280B, SLC26A2, DMXL1, OR52A1, MACROD2 and REV1 genes, which are associated with regulation of spermatogenesis, post-testicular maturation, Cl^- channel activity, V-ATPase-mediated intracellular vesicle acidification, a mono-ADP-ribosyl hydrolase and ATR-Chk1 checkpoint activation. GO analysis of filtered genes with significant variations between good and poor-quality semen showed enrichment in important pathways related to semen quality such as MAPK signalling pathway, Akt signalling pathway, focal adhesion, cAMP signalling pathway, and Rap1 signalling pathway. Network analysis of filtered genes in poor-quality semen showed variations in pathways of purine metabolism, pyrimidine metabolism, prolactin signalling pathway and RNA cap-binding complex. It is inferred that SNP in genes involved in maintaining sperm functions could be the reason for poor-quality semen production in bulls, and the identified SNPs hold potential to be used as biomarkers for semen quality in bulls.

Morphological Features of the Testis among Autoimmune Mouse Model and Healthy Strains

Autoimmune diseases play a critical role in the progression of infertility in both sexes and their severity has been reported to increase with age. However, few reports have discussed their effect on the morphological features of the testis. Therefore, we compared the morphological alterations in the testes of autoimmune model mice (MRL/MpJ-Faslpr) and the control strain (MRL/MpJ) with those of their background strain (C57BL/6N) at 3 and 6 months. Furthermore, we analyzed the changes in spermatocytes, Sertoli cells, immune cells, and Zonula occludens-1 junctional protein by immunohistochemical staining. The MRL/MpJ-Faslpr mice showed a significant increase in the serum Anti-double stranded DNA antibody level, relative spleen weight, and seminiferous luminal area when compared with other studied two strains. In contrast, a significant decrease in the relative testis weight, and numbers of both Sertoli, meiotic spermatocyte was observed in MRL/MpJ-Faslpr and MRL/MpJ mice compared with C57BL/6N mice especially at 6 months. Similarly, Zonula occludens-1 junctional protein positive cells showed a significant decrease in the same strains at 6 months. However, no immune cell infiltration could be observed among the studied three strains. Our findings suggest that the increase in autoimmune severity especially with age could lead to infertility through loss of spermatogenic and Sertoli cells, rather than the disturbance of the blood-testis barrier.

Expression of Rad51 and the histo-morphological evaluation of testis of the sterile male cattle-yak

Meiotic recombination is key to the repair of DNA double-strand break damage, provide a link between homologs for proper chromosome segregation as well as ensure genetic diversity in organisms. Defects in recombination often lead to sterility. The ubiquitously expressed Rad51 and the meiosis-specific DMC1 are two closely related recombinases that catalyze the key strand invasion and exchange step of meiotic recombination. This study cloned and sequenced the coding region of cattle-yak Rad51 and determined its mRNA and protein expression levels, evaluated its molecular and evolutionary relationship as well as evaluated the histo-morphological structure of testes in the yellow cattle, yak and the sterile cattle-yak hybrid. The Rad51 gene was amplified using PCR, cloned and sequenced using testicular cDNA from yak and cattle-yak. Real-time PCR was used to examine the expression levels of Rad51/DMC1 mRNA in the cattle, yak and cattle-yak testis while western blotting, immunofluorescence and immunohistochemistry were used to assess the protein expression and localization of Rad51/DMC1 protein in the testicular tissue sections. The results revealed that the mRNA and protein expression of Rad51 and DMC1 are extremely low in the male cattle-yak testis with a corresponding higher incidence of germ cell apoptosis. There was also thinning of the germinal epithelium possibly due to the depletion of the germ cells leading to the widening of the lumen area of the cattle-yak seminiferous tubule. Our findings provide support for the hypothesis that the low expression of Rad51 and DMC1 may contribute to the male hybrid sterility in the cattle-yak.

Cellular and Molecular Insights Into the Etiology of Subfertility/Infertility in Crossbred Bulls (Bos taurus × Bos indicus): A Review

Crossbreeding of indigenous cattle (Bos indicus) with improved (Bos taurus) breeds gained momentum and economic relevance in several countries to increase milk production. While production performance of the crossbred offspring is high due to hybrid vigor, they suffer from a high incidence of reproductive problems. Specifically, the crossbred males suffer from serious forms of subfertility/infertility, which can have a significant effect because semen from a single male is used to breed several thousand females. During the last two decades, attempts have been made to understand the probable reasons for infertility in crossbred bulls. Published evidence indicates that testicular cytology indices, hormonal concentrations, sperm phenotypic characteristics and seminal plasma composition were altered in crossbred compared to purebred males. A few recent studies compared crossbred bull semen with purebred bull semen using genomics, transcriptomics, proteomics and metabolomics; molecules potentially associated with subfertility/infertility in crossbred bulls were identified. Nevertheless, the precise reason behind the poor quality of semen and high incidence of sub-fertility/infertility in crossbred bulls are not yet well defined. To identify the underlying etiology for infertility in crossbred bulls, a thorough understanding of the magnitude of the problem and an overview of the prior art is needed; however, such systematically reviewed information is not available. Therefore, the primary focus of this review is to compile and analyze earlier findings on crossbred bull fertility/infertility. In addition, the differences between purebred and crossbred males in terms of testicular composition, sperm phenotypic characteristics, molecular composition, environmental influence and other details are described; future prospects for research on crossbred males are also outlined.

Comparative Transcriptomic Analysis of Spermatozoa From High- and Low-Fertile Crossbred Bulls: Implications for Fertility Prediction

Crossbred bulls produced by crossing Bos taurus and Bos indicus suffer with high incidence of infertility/subfertility problems; however, the etiology remains poorly understood. The uncertain predictability and the inability of semen evaluation techniques to maintain constant correlation with fertility demand for alternate methods for bull fertility prediction. Therefore, in this study, the global differential gene expression between high- and low-fertile crossbred bull sperm was assessed using a high-throughput RNA sequencing technique with the aim to identify transcripts associated with crossbred bull fertility. Crossbred bull sperm contained transcripts for 13,563 genes, in which 2,093 were unique to high-fertile and 5,454 were unique to low-fertile bulls. After normalization of data, a total of 776 transcripts were detected, in which 84 and 168 transcripts were unique to high-fertile and low-fertile bulls, respectively. A total of 176 transcripts were upregulated (fold change > 1) and 209 were downregulated (<1) in low-fertile bulls. Gene ontology analysis identified that the sperm transcripts involved in the oxidative phosphorylation pathway and biological process such as multicellular organism development, spermatogenesis, and in utero embryonic development were downregulated in low-fertile crossbred bull sperm. Sperm transcripts upregulated and unique to low-fertile bulls were majorly involved in translation (biological process) and ribosomal pathway. With the use of RT-qPCR, selected sperm transcripts (n = 12) were validated in crossbred bulls (n = 12) with different fertility ratings and found that the transcriptional abundance of ZNF706, CRISP2, TNP2, and TNP1 genes was significantly (p < 0.05) lower in low-fertile bulls than high-fertile bulls and was positively (p < 0.05) correlated with conception rate. It is inferred that impaired oxidative phosphorylation could be the predominant reason for low fertility in crossbred bulls and that transcriptional abundance of ZNF706, CRISP2, TNP2, and TNP1 genes could serve as potential biomarkers for fertility in crossbred bulls.

Male hybrid sterility in the cattle-yak and other bovines: a review

Hybridization is important for both animal breeders attempting to fix new phenotypic traits and researchers trying to unravel the mechanism of reproductive barriers in hybrid species and the process of speciation. In interspecies animal hybrids, gains made in terms of adaptation to environmental conditions and hybrid vigor may be offset by reduced fertility or sterility. Bovine hybrids exhibit remarkable hybrid vigor compared to their parents. However, the F1 male hybrid exhibits sterility, whereas the female is fertile. This male-biased sterility is consistent with the Haldane rule where heterogametic sex is preferentially rare, absent, or sterile in the progeny of two different species. The obstacle of fixing favorable traits and passing them to subsequent generations due to the male sterility is a major setback in improving the reproductive potential of bovines through hybridization. Multiperspective approaches such as molecular genetics, proteomics, transcriptomics, physiology, and endocrinology have been used by several researchers over the past decade in an attempt to unravel the potential mechanisms underlying male hybrid sterility. However, the mechanism of sterility in the hybrid male is still not completely unravelled. This review seeks to provide an update of the mechanisms of the sterility in the cattle-yak and other bovines.

Effect of Zirconium oxide nanoparticle on serum level of testosterone and spermatogenesis in the rat: An experimental study

BACKGROUND

Zirconium nanoparticles are used as health agents, pharmaceutical carriers, and in dental and orthopedic implants.

OBJECTIVE

This studyaimed to investigate the effects of Zirconium oxide nanoparticles on the process of spermatogenesis in rat.

MATERIALS AND METHODS

In this experimental study, 32 male Wistar rats (150-200 gr), with range of age 2.5 to 3 months were used and divided into four groups of eight per each. The control group received 0.5 ml of distilled water and the three experimental groups received 50, 200, and 400 ppm doses of Zirconium oxide nanoparticles solution over a 30-day period, respectively. At the end of the experiment, tissue sections were taken from the testis and stained with hematoxylin-eosin. Serum concentration of testosterone was measured by enzyme-linked immunosorbent assay.

RESULTS

In the experimental group receiving 400 ppm Zirconium oxide nanoparticles, the number of Spermatogonia cells (p ≤ 0.01), Spermatocytes (p ≤ 0.01), Spermatids (p ≤ 0.001), and sertoli and Leydig cells (p ≤ 0.05) showed a significant decrease compared to the control group. Serum testosterone concentration did not change significantly in all experimental groups receiving Zirconium oxide nanoparticles compared to the control group. Experimental group received 400 ppm Zirconium oxide nanoparticles shrinkage of seminal tubules and reduced lumen space compared to control group.

CONCLUSION

Zirconium oxide nanoparticles are likely to damage the testes by increasing Reactive oxygen species production and free radicals.

A High Phosphorus Diet Impairs Testicular Function and Spermatogenesis in Male Mice with Chronic Kidney Disease

Hyperphosphatemia is a serious complication in chronic kidney disease (CKD) that occurs due to insufficient excretion of phosphorus during failure of renal function. Both CKD and an excessive phosphorus intake have been reported to increase oxidative stress and result in poor male fertility, but little is known about the reproductive function of the CKD under a poorly controlled phosphate intake. Eight-week-old C57BL/6 mice (n = 66) were randomly divided into four groups: a sham operation group received a chow diet as control (SC group, n = 14), CKD-induced mice received a chow diet (CKDC group, n = 16), control mice received a high phosphorus (HP) diet (SP group, n = 16), and CKD-induced mice received a HP diet (CKDP group, n = 20). CKD was induced by performing a 5/6 nephrectomy. The chow diet contained 0.6% phosphorus, while the HP diet contained 2% phosphorus. Impaired testicular function and semen quality found in the CKD model may result from increased oxidative stress, causing apoptosis and inflammation. The HP diet aggravated the negative effects of testicular damage in the CKD-induced mice.

Sub-fertility in crossbred bulls: deciphering testicular level transcriptomic alterations between zebu (Bos indicus) and crossbred (Bos taurus x Bos indicus) bulls

BACKGROUND

The incidence of poor semen quality and sub-fertility/infertility is higher in crossbred as compared to Zebu males. Several attempts have been made to understand the possible reasons for higher incidence of fertility problems in crossbred males, at sperm phenotype, proteome and genome level but with variable results. Since the quality of the ejaculated spermatozoa is determined by the testicular environment, assessing the testicular transcriptome between these breeds would help in identifying the possible mechanisms associated with infertility in crossbred bulls. However, such information is not available. We performed global transcriptomic profiling of testicular tissue from crossbred and Zebu bulls using Agilent Bos taurus GXP 8X60k AMADID: 29411 array. To the best of our knowledge, this is the first study comparing the testicular mRNAs between crossbred and Zebu bulls.

RESULTS

Out of the 14,419 transcripts detected in bovine testis, 1466 were differentially expressed between crossbred and Zebu bulls, in which 1038 were upregulated and 428 were downregulated in crossbred bulls. PI4KB and DPY19L2 genes, reported to be involved in sperm capacitation and acrosome formation respectively, were among the top 10 downregulated transcripts in crossbred testis. Genes involved in ubiquitination and proteolysis were upregulated, while genes involved in cell proliferation, stem cell differentiation, stem cell population maintenance, steroidogenesis, WNT signalling, protein localization to plasma membrane, endocannabinoid signalling, heparin binding, cAMP metabolism and GABA receptor activity were downregulated in crossbred testis. Among the 10 genes validated using qPCR, expression of CCNYL, SOX2, MSMB, SPATA7, TNP1, TNP2 and CRISP2 followed the same trend as observed in microarray analysis with SPATA7 being significantly downregulated and transition proteins (TNP1, TNP2) being significantly upregulated in crossbred bulls.

CONCLUSIONS

Abundant proteolysis by ubiquitination and downregulation of WNT signaling, cell proliferation, differentiation and steroidogenesis might be associated with higher incidence of poor semen quality and/or sub-fertility/infertility in crossbred bulls as compared to Zebu bulls. Downregulation of SPATA7 (Spermatogenesis Associated 7) and upregulation of transition proteins (TNP1 and TNP2) in crossbred bull testis might be associated with impaired spermatogenesis processes including improper chromatin compaction in crossbred bulls.

Effects of a standardized 40% ellagic acid pomegranate (Punica granatum L.) extract on seminiferous tubule histopathology, diameter, and epithelium thickness in albino Wistar rats after heat exposure

Background and Aim:

It has long been known that the spermatogenic tissue is very sensitive to temperatures higher than its physiologic temperature and causing cessation of activity and resulting in sterility. This study investigated the effect of a standardized 40% ellagic acid extract of pomegranate on the histopathology, diameter, and epithelial thickness of seminiferous tubules in albino rats exposed to heat.

Materials and Methods:

Twenty-five male albino Wistar rats were randomized at 7-8 months of age to five treatment groups. Group C was not treated; Group T0 was treated with 0.5% of Na carboxymethyl cellulose (CMC) 2 ml/day and exposed to heat. T1, T2, and T3 were treated with 75, 150, and 300 mg/kg/day of a standardized 40% ellagic acid extract of pomegranate (Punica granatum L.), respectively. The animals were orally administered Na CMC or pomegranate extract and were exposed to sunlight for 15 min at 40°C-42°C for 14 days. The animals were sacrificed on day 15 and the testes were removed for histological evaluation and measurement of seminiferous tubule diameter and epithelium thickness.

Results:

The diameter of seminiferous tubules from rats exposed to heat and treated with 300 mg/kg/day pomegranate extract was larger and the epithelia thicker than those in the other groups (p<0.05). The protective effects of the standardized 40% ellagic acid extract may have been mediated by its antioxidant activity.

Conclusion:

Compared with controls, administration of 300 mg/kg/day of a standardized 40% ellagic acid extract of P. granatum L. for 14 days increased seminiferous tubule diameter and epithelium thickness in albino Wistar rats exposed to heat.

Ellagic acid: A promising protective remedy against testicular toxicity induced by arsenic

Chronic exposure to arsenic, an inducer of oxidative stress, is one of the major causes of male infertility. Therefore, the present study investigated the protective role of Ellagic acid (EA), as a natural antioxidant, against testicular toxicity evoked by arsenic. Thirty-five male Wistar rats were divided into 5 treatment groups. Group 1 served as control, group 2 were orally exposed to sodium arsenite (SA, 10 mg/kg; 21 days), groups 3 and 4 were initially exposed to SA for 7 days and then were treated with both EA (10 and 30 mg/kg) and SA up to 21 days, and group 5 was treated with EA for 14 days. After this period, biochemical and histopathological parameters were evaluated in serum samples and testicular tissue. SA markedly reduced levels of serum testosterone, total antioxidant capacity, reduced glutathione as well as the activity of antioxidant enzymes. Furthermore, SA enhanced levels of malondialdehyde, tumor necrosis factor-α, interleukin-1β and nitric oxide in testes. Treatment with EA was found to reduce testicular arsenic accumulation and oxidative stress parameters. In addition, EA improved the serum testosterone level, testicular antioxidant markers and histological parameters after exposure to SA. EA may emerge as a promising therapeutic option to protect testes from arsenic-induced toxicity through reducing oxidative stress and inflammatory responses.