Identification of heat shock protein70-2 and protamine-1 mRNA, proteins, and analyses of their association with fertility using frozen-thawed sperm in Madura bulls

Sperm HSP70: may not be an age-dependent gene but is associated with field fertility in Bali bulls (Bos sondaicus)

This study aimed to analyze the characteristics of the HSP70 gene and protein in spermatozoa of Bali bulls of different age groups and to examine its potential as a biomarker determining bull fertility. This study used frozen semen produced from six Bali bulls divided into two groups based on age (≤ 9 years and ≥ 12 years). Parameters of frozen semen quality analyzed included sperm motility and kinetics using computer-assisted semen analysis, sperm morphological defects using Diff-Quick staining, acrosome integrity using FITC-PNA staining, and DNA fragmentation using acridine orange staining. HSP70 gene expression characterization was analyzed using qRT-PCR, and HSP70 protein abundance was analyzed using enzyme immunoassays. Fertility field data were obtained by analyzing the percentage conception rate for each bull based on the artificial insemination service data contained in the Indonesian-integrated system of the National Animal Health Information System (iSIKHNAS). The results showed significant differences (P<0.05) in total and progressive motility, morphological defects of the neck and midpiece, and tail of sperm, and acrosome integrity between the age groups of Bali bulls. HSP70 gene expression and protein abundance showed no significant differences (P>0.05) in different age groups. HSP70 gene expression correlated with fertility rate (P<0.05). Age affected several semen quality parameters but did not affect HSP70 gene expression and protein abundance. The HSP70 gene molecule could be a biomarker that determines the fertility of Bali bulls.

Bovine nucleoprotein transitions genes and protein abundance as valuable markers of sperm motility and the correlation with fertility

Bovine nucleoprotein transitions (TNPs), specifically TNP1 and TNP2, are essential molecules in sperm nucleus rich in arginine and lysine. These molecules act in the phase between histone expulsion and before incorporation of protamine in the spermatid nucleus. Therefore, this study aimed to analyze genes and protein abundance of TNP1 and TNP2 in sperm to determine the potential as motility markers and correlation with fertility in the field. An objective evaluation method, CASA-Sperm Vision, was used to separate 22 bulls into two groups (mg-A and mg-B) based on their increasing motility. Sperm quality parameters were also examined including velocity, mitochondrial membrane potential (MMP) by the JC-1 method, head defects using William staining, and DNA fragmentation by Halomax. TNPs genes abundance was performed using the RT-qPCR method, and the protein abundance was examined with the EIA approach. The fertility rate was also analyzed based on the conception rate generated from each bull in the field, with the data obtained from iSIKHNAS. The results showed that TNPs genes and protein abundance were significantly higher (P < 0.05) in mg-A compared to mg-B, followed by various sperm quality parameters and fertility rates (P < 0.05). Positive correlations were found in TNPs genes and protein abundance with motility, velocity, MMP, and fertility (P < 0.01). Meanwhile, a negative correlation (P < 0.01) was found between head defects and DNA fragmentation. These results showed the potential of TNPs as sperm motility markers and bull fertility.

A proteomic approach to identifying spermatozoa proteins in Indonesian native Madura bulls

Proteins assist sperm mature, transit the female reproductive tract, and recognise sperm oocytes. Indigenous Indonesian bulls, Madura bulls, have not been studied for reproductive proteomics. As local Indonesian beef livestock, Madura cattle assist in achieving food security; hence, their number must be improved. Thus, the identification of molecular proteomics-based bull fertility biomarkers is needed. This study aimed to characterise the sperm fertility function of the superior Madura bull (Bos indicus × Bos Javanicus) spermatozoa proteome. Frozen semen from eight Madura superior bulls (Bos indicus × Bos javanicus) aged 4-8 years was obtained from the artificial insemination centre (AIC) in Singosari and Lembang. Madura superior bulls are those that have passed the bull breeding soundness evaluation. Frozen sperm were thawed and centrifuged at 3000 × g for 30 min. Proteins in sperm were characterised through proteomic analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The resulting gene symbols for each protein were then subjected to bioinformatics tools, including UniProt, DAVID, and STRING databases. Regarding sperm fertility, the analysis revealed that 15 proteins were identified in the sperm of Madura bulls. Amongst the identified proteins, the superior Madura bull sperm contained several motilities, energy-related proteins, and chaperone proteins. A substantial portion of characterised proteins are linked to metabolic pathways and the tricarboxylic acid (TCA) cycle, contributing to sperm energy production. In conclusion, the first in-depth proteome identification of sperm related to sperm quality and bull fertility of a unique indigenous Madura breed of Indonesia was performed using the LC-MS/MS proteomic method. These findings may serve as a reference point for further studies related to the functions of bovine sperm and biomarkers of fertility and sperm quality.

Sperm Head Morphology Alterations Associated with Chromatin Instability and Lack of Protamine Abundance in Frozen-Thawed Sperm of Indonesian Local Bulls

This study aimed to analyze various alterations in the morphology of the sperm head and its association with nucleus instability and insufficient sperm protamine. Frozen-thawed semen from twenty local Indonesian bulls was used for all stages in this study. The results of sperm head defect assessments are used for bull grouping, high (HD) and low (LD). Sperm DNA damage was assessed using Acridine Orange and Halomax. The PRM1 protein abundance was carried out using an enzyme immunoassay, while PRM1 gene expression was carried out using the RT-qPCR. PRM deficiency was performed using CMA3. Several kinds of sperm head defects in the HD were significantly higher (p < 0.05) than in the LD bulls. Sperm DNA damage showed a significant (p < 0.05) difference between the HD and LD bulls. PRM1 abundance was significantly (p < 0.05) decreased in HD bulls. PRM deficiency was significantly (p < 0.05) higher in HD bulls than in LD bulls. PRM deficiency in bulls correlated significantly (p < 0.01) with sperm head defects, DNA damage, and PRM1 abundance. The lack of sperm protamine might affect the sperm nucleus's stability and induce morphological alterations in the sperm head.