Search

Sperm biomolecules impact the reproductive success of a bull in many ways from fertilization to the health of the offspring. The energy produced within the sperm enables them to remain motile and allows them to participate in fertilization events. In this study, we deciphered the genes associated with energy production and their influence on the fertility rate. Post-thaw buffalo semen samples (n=21) were analysed for sperm kinematics and field fertility for selecting high (n=5) and low (n=5) fertile samples. Sperm total RNAs were extracted using a double lysis method followed by column-based extraction and sequenced using the Illumina platform. The expression levels of the genes involved in energy-regulating pathways were analyzed. Among these genes, 14.6% were significantly (p<0.05) differentially expressed between high and low fertile sperm. The expression levels of up-regulated genes such as JAK3, DDX5, PRKCZ, CHD4, CHD5, and ADCY3 had a strong positive correlation (r>0.5) with progressive motility and velocities. The up-regulated genes were involved in chemokine signaling (ADCY2 and JAK2, p=0.0001), calcium signaling (AGTR1 and SLC25A4,p=0.0002) and oocyte meiosis (ADCY2 and ADCY3, p=0.049). The increase in the expression of ATP-producing genes substantiate the improved progressive motility (64.51±5.79 vs 33.07±3.34 %), curvilinear velocity (70.58±4.32 vs 50.15±4.92 μm/sec), straight-line velocity (39.84±3.16 vs 26.02±2.52 μm/sec) and average path velocity (49.46±3.59 vs 32.99±3.45 μm/sec) in high fertile bulls compared to low fertile bulls. The study suggests that the expression level of differentially expressed genes associated with energy-regulating pathways influences the fertilizing ability of sperm. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify the sperm-expressed genes and their pathways in maintaining acrosomal integrity for elucidating the regulatory genes involved in determining bull fertility. Semen samples collected from Holstein-Friesian bulls (n=12) were analyzed for acrosomal integrity and were grouped into high acrosomal integrity (n=6) and low acrosomal integrity (n=6). In these sperm samples, total RNA was isolated and subjected to whole transcriptome profiling using Illumina platform. Bioinformatic analyses led to the identification of 1601 up-regulated (TMCO2, GTSF1, SWI5, CCDC174 and CABS1) and 567 down-regulated (MYCB, RPS21 and PPIA) genes. The study also validated the expression levels of CCDC174 and TMCO2 using real-time PCR. The pathways [log2 (p-value)] such as spermatid development (12.17), protein transport (9.57) and mitochondrial electron transport (10.20) were enriched in the up-regulated genes. These identified pathways and their associated transcripts in high acrosome integrity group suggest that these pathways are essential for maintaining acrosome integrity and sperm fertility in bulls. [ABSTRACT FROM AUTHOR]

Background: Terminally differentiated mammalian sperm are exposed to gradients of viscosity, pH, and osmolality both in the male and female reproductive tract during their perilous journey to quest the ovum. The complex physicochemical factors play an integral role in preparing sperm for the fertilization process. Objectives: To elucidate the influence of the reproductive tract microenvironment especially viscosity, pH, and osmolality in regulating sperm functional and fertilization competence. Materials and Methods: The data used in this review were collected from the research papers and online databases focusing on the influence of viscosity, pH, and osmolality on sperm function. Discussion: The gradients of viscosity, pH, and osmolality exist across various segments of the male and female reproductive tract. The changes in the viscosity create a physical barrier, pH aid in capacitation and hyperactivation, and the osmotic stress selects a progressive sperm subpopulation for accomplishing fertilization. The sperm function tests are developed based on the concept that the male genotype is the major contributor to the reproductive outcome. However, recent studies demonstrate the significance of sperm genotype‐environment interactions that are essentially contributing to reproductive success. Hence, it is imperative to assess the impact of physicochemical stresses and the adaptive ability of the terminally differentiated sperm, which in turn would improve the outcome of the assisted reproductive technologies and male fertility assessment. Conclusion: Elucidating the influence of the reproductive tract microenvironment on sperm function provides newer insights into the procedures that need to be adopted for selecting fertile males for breeding, and ejaculates for the assisted reproductive technologies. [ABSTRACT FROM AUTHOR]

This study aimed to assess the effect of the insulin-like grow factor 1 (IGF-1) treatment during in vitro maturation on the gene expression and developmental ability of ovine oocytes. Ovine cumulus-oocyte complexes (COC) were matured in vitro without (control) or with the supplementation of IGF-1 (100 ng/ml) and then subjected to in vitro fertilization and culture. The rate of oocyte maturation and embryo development was recorded and expression of the selected genes (involved in the PI3K/Akt and apoptosis signaling) was assessed in the matured oocytes. The IGF-1 treatment significantly (p <.05) improved the oocyte maturation rate (%) as compared to the control (81.5 ± 2.40 vs. 73.6 ± 0.94). Similarly, as compared to the control, the IGF-1 treatment significantly (p <.05) improved the rate (%) of cleavage (54.7 ± 1.58 vs. 67.2 ± 3.65) and the formation of 4–8 cell embryos (30.7 ± 2.89 vs. 44.1 ± 4.01) and morula (20.7 ± 2.08 vs. 32.8 ± 2.78). The IGF-1 treatment significantly (p <.05) upregulated the expression of IGF1R, PI3KR1, AKT1 and BCL2 and downregulated the expression of GSK3β, FOXO3 and CASP9 in the matured oocytes. In conclusion, the IGF-1 treatment significantly improved the developmental competence of ovine oocytes through the regulation of the PI3K/Akt and apoptosis signaling. [ABSTRACT FROM AUTHOR]

The influence of CL on follicular development and the changes in the follicular fluid composition leading to attainment of follicular dominance and ovulation has not been intensively studied in the buffalo. In the present study, the buffalo ovarian follicular fluids were collected from live animals by transvaginal ultrasound guided follicular aspiration. Based on the size of the follicles and stage of the estrous cycle, follicles were classified into 3-5 mm (small), 5-8 mm (medium) and >8 mm (large ovulatory and non-ovulatory). The follicles were classified into healthy and atretic follicles based on nuclear quality as assessed by histological staining. The stage and health status of the follicles were confirmed by the serum progesterone and follicular fluid hormonal concentration. Hormone concentration (serum and follicular fluid) and HDL cholesterol were estimated in follicular fluids, and expression of LH and 3β hydroxysteroid dehydrogenase (3β-HSD) receptors was studied in granulosa cells of different sizes. The study revealed that the presence of CL influences the growth of the follicles of all stages. Significantly high follicular fluid progesterone in the ovulatory follicles indicated that the luteinization of granulosa cells starts even before ovulation of the dominant follicle. The medium-sized follicles with high estradiol concentration may attain dominance, whereas the follicle with high progesterone concentration may undergo atresia. A significantly low HDL cholesterol level in healthy follicles indicates effective steroidogenesis as evidenced by the higher expression of LH and 3β-HSD receptors in the granulosa cells. [ABSTRACT FROM AUTHOR]

Bulls with acceptable semen quality vary in actual field fertility and this can be elucidated by studying the expression levels of mRNAs in the sperm. The present study aimed at assessing the variations in the sperm gene expression levels of PRM1, CCDC174, RPL36A, TMCO2, SWI5 and OIT3 in bulls differing in fertility status. Frozen semen samples from Holstein-Friesian bulls were classified into high-fertile (n = 8, average field conception rate = 46.1 ± 0.51, p < 0.001) and sub-fertile (n = 7, average field conception rate = 39.4 ± 0.69) groups. In the post-thaw semen samples, sperm kinematics, structural and functional membrane integrities, mitochondrial membrane potential and chromatin distribution were analyzed. The sperm total RNA was subjected to gene expression studies by Real-Time PCR. Multivariate regression analysis was performed using gene expression levels and conception rates. The sperm functional attributes did not differ significantly between the groups. The relative mRNA levels (fold change) of CCDC174 (6.20), RPL36A (4.66), SWI5 (1.86) and OIT3 (1.53) were higher in high-fertile bulls. Further, the expression level of the CCDC174 gene was significantly (p = 0.02) up-regulated in high-fertile bulls. The fertility prediction multivariate model with genes, CCDC174, RPL36A, TMCO2 and OIT3 had the maximum coefficient of determination (R2 = 0.68) with the field conception rate. This model had 93.3% bull fertility prediction accuracy with 100% sensitivity and 87.5% specificity. The study suggests that the expression level of CCDC174 can be used as a potential marker for assessing bull fertility. [ABSTRACT FROM AUTHOR]