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Oxidative stress damages the structure of sperm and affects its fertility. Further maturation and storage of spermatozoa occur in the epididymis. Thus, a balanced environment between free-radical production and the antioxidant-enzyme system is important. This study aimed to investigate differences in antioxidative activity in epididymis between high and low fertility levels of Hu sheep. A total of 179 Hu ram lambs aged 56 days were fed up to 6 months in the same environment. After feeding trial, all rams were slaughtered. According to the epididymis weight, cauda sperm concentration, and histo-morphological observation, 18 individuals were selected and divided into low fertility (n = 9) and high fertility (n = 9) groups. The RNA sequencing results showed 1404 differentially expressed genes (DEGs), with 735 genes upregulated and 669 genes downregulated in the high fertility group compared with the low fertility group. Sixteen DEGs related to lipid metabolism and oxidative stress, including GPX3, GPX5, LRP1, PLCB1, CRISP2, BSPH1, and ACSBG1, were screened by qPCR, and results were correlated well with the sequencing data. Antioxidative indices such as total antioxidant capacity (21.29 ± 5.97 vs. 30.23 ± 4.56 μM/gprot) and glutathione peroxidase (39.75 ± 7.61 vs. 68.84 ± 12.51 U/mgprot) increased in the high fertility group. However, the relative expression of mtDNA and malondialdehyde concentration (0.75 ± 0.15 vs. 0.54 ± 0.10 nmol/mgprot) and the reactive oxygen species (ROS) content significantly decreased (P < 0.05). Therefore, epididymis from high-fertility group had strong antioxidative activity and protected spermatozoa from ROS., (Copyright © 2022 Elsevier Inc. All rights reserved.)

ADP-dependent glucokinase (ADPGK) plays an important role instead of hexokinase in regulating energy metabolism via the Embden–Meyerhof–Parnas Pathway. And energy provided via glycolysis promotes testis development and spermatogenesis. In this study, 466 Hu sheep were screened for mutations in the ADPGK gene to examine the association of the ADPGK gene polymorphisms with the testis traits and spermatogenesis. The NC_056060.1: g.31295 C > T SNP was found in the 3′-UTR region, resulting in two genotypes CC and TC type with genotypic frequencies of 0.66 and 0.34, respectively. This mutation was significantly associated with testis weight, testis long circumference, testis short girth, epididymis weight, and sperm concentration (p < 0.05). Moreover, TC genotype individuals had an increased tendency in the expression of the ADPGK gene and had significant reproductive performance advantages compared with CC genotype individuals in the study. And compared with the small testes (<50 g), the ADPGK gene expression of big testes (>160 g) increased significantly. This indicates an association between the ADPGK gene and reproductive organ parameters and sperm count in selected Hu sheep breed, and this SNP may serve as an effective DNA molecular marker for marker-assisted selection in Hu sheep breeding programs. [ABSTRACT FROM AUTHOR]