Changes in colostrum ingredients of Hu sheep, as well as the missense mutation genes associated with colostrum yield.

This study focused on the changes in the composition and immune evolution in milk from birth to 144 h postpartum and the genes associated with the colostrum yield of Hu sheep. Twelve Hu sheep, which were bred carefully under animal health standards and have a litter size of two kids and similar gestation length (149 ± 1 days), were used. Lambs were transferred into their own cots to avoid interference. The compositional content (i.e., fat, protein, and lactose) and some other properties, including daily colostrum yield, DM, and SNF, were determined. In addition, immunity molecules (IgG, IgA, and IgM concentrations) received remarkable attention. The DM, SNF, fat, and protein contents were higher in the first days postpartum and then dropped quickly from the time of birth to 144 h postpartum. However, the lactose content displayed an increasing pattern and reached normal milk percentage at 48 h. The highest IgG (103.17 mg/mL), IgA (352.82 µg/mL), and IgM (2.79 mg/mL) colostrum concentrations were observed at partum, decreased quickly, and finally stabilized. The change law of concentration of IgA and IgM in colostrum are the same with IgG. Furthermore, the whole-genome resequencing was performed, and a missense variant locus in the SRC gene and two missense locus variants in the HIF1A gene were significantly associated with the colostrum yield of sheep by using the whole-genome selection signal detection analysis. In conclusions, colostrum contains abundant nutrients especially immunoglobulin, and the HIF1A gene may be used as candidate genes for colostrum yield, which has important information as a basic knowledge for the Hu sheep breeding program.

The c.612A>G mutation of MC4R affects constitutive activity and signaling in domestic goats.

As a key gene for balancing energy and regulating feeding behavior, MC4R is relevant to the growth of ruminants. In this presentation, a highly conserved c.612A>G site in the coding sequence (CDS) of MC4R has been selected during a selective sweep analysis of 35 Yiling goats and 20 other wild goats. This site mutation results in an amino acid change from Ile to Met. The genotyping analysis of the c.612A>G site revealed that the A allele was the dominant allele in the domestic goat populations, while the wild goat individuals only had the G allele. For a better understanding of the biological significance of this site, we examined the protein localization and signal detection to explain the function of the two MC4R receptors. The results showed that both the M204 and I204 receptors can normally localize on the membrane. When stimulating the M204 type without α-MSH, it was defective at the level of basal cAMP and decreased significantly against the I204 type. In contrast, the signaling capacity of the M204 receptor was also lower than that of I204 under the stimulation of α-MSH. In the ERK1/2 pathway, stimulating MC4R with NDP-α-MSH, both the M204 and I204 receptors had normal pERK1/2 levels. These results indicate that the p.I204M mutation may change the function by damaging the constitutive activity and signaling, and thus may regulate goats' appetite. This study has potential application for rearing domestic goats.

Contribution of the mutation T865G in TPH1 gene to the genetic potentiality of housed Mongolian sheep to year-round breeding.

Seasonal breeding is widespread in sheep and significantly affects the development of the housed sheep industry. To improve and balance the reproduction performance of sheep, year-round breeding has the goal of modern sheep farming. The tryptophan hydroxylase (TPH), which initiates and regulates biosynthesis of melatonin, is an important player in the formation of mammalian year-round breeding. However, little is known about its role in regulation of sheep seasonal breeding. In this study, a missense mutation, T865G in TPH1 gene was detected in 328 individuals of six Mongolian sheep groups. It was positively selected among Mongolian sheep. This mutation may appear between 13,683 and 350,973 years ago and only exist in Hu sheep now. In Hu sheep, the frequency of allele T was 89.66%, and that of allele G was 10.34%. The TPH1 protein structure and property analysis suggested that this mutation from T to G affect the three-dimensional structure and reduce the hydropathicity of catalytic core. When the allele is T, the protein activity is twice that of the allele G, and their difference was significant (p < .05). In conclusion, T865G is an ancient mutation of TPH1 gene and affects the function of TPH protein, which may contribute to the genetic potentiality of Mongolian sheep to year-round breeding.

Polygenic co-expression changes the testis growth, hormone secretion and spermatogenesis to prompt puberty in Hu sheep.

In most male mammals, testis undergoes increased proliferation activity and the onset of spermatogenesis during pubertal development. However, their gene expression patterns and roles in sheep remain unclear. Therefore, we used Illumina Hiseq 2000 sequencing to identify differentially expressed genes (DEGs) from 0, 30, 60, 90, 120, 150 and 180 postnatal days and characterize the transcriptional level of sheep testicular development. Among them, the DEGs changed the most in 90-150 stages. a total of 2546 (1454 up and 1092 down) and 6867 (4683 up and 2184 down) DEGs were identified in D120 vs. D90 and D150 vs. D120, respectively. Functional enrichment analysis revealed that in earlier pubertal development, testis showed higher gene expression in organ morphogenesis, vasculogenesis, neurogenesis and hormone secretion, while in later pubertal development, genes with higher expression mainly concentrated in regulating spermatogenesis process. These results indicated that testis development undergoes the transition from organ growth to spermatogenesis and the genes related to hormone secretion were expressed highly earlier than spermatogenesis during pubertal process. In addition, we found several genes such as ZFP36, TNF, HSD3B1, HSD11B2 played key roles in androgen secretion and SPAG family, SYCP family, SPATA family, SPO11, CABYR, TNP1, TNP2 and CFAP43 performed functions during spermatogenesis process. Taken together, multi-genes cooperation prompt testis development in pubertal process. Our transcriptional atlas of sheep testis provides a comprehensive insight about testicular development and pubertal process.