Understanding the genetic composition of indigenous goats is essential to promote the scientific conservation and sustainable utilization of these breeds. The Jianchang Black (JC) goat, a Chinese native breed, is solid black, exhibits crude feed tolerance, but is characterized by a low growth rate and small body size. Based on the whole-genome sequencing data for 30 JC, 41 Jintang Black (JT), and 40 Yunshang Black (YS) goats, and 21 Bezoar ibexes, here, we investigated the genetic composition of JC goats by conducting analyses of the population structure, runs of homozygosity (ROH), genomic inbreeding, and selection signature. Our results revealed that JT and YS showed a close genetic relationship with a non-negligible amount of gene flows but were genetically distant from JC, apart from Bezoars. An average of 2039 ROHs were present in the autosomal genome per individual. The ROH-based inbreeding estimates in JC goats generally showed moderate values ranging from 0.134 to 0.264, mainly due to rapid declines in the effective population size during recent generations. The annotated genes (e.g., IL2, IL7, and KIT) overlapping with ROH islands were significantly enriched in immune-related biological processes. Further, we found 61 genes (e.g., STIM1, MYO9A, and KHDRBS2) under positive selection in JC goats via three complementary approaches, which may underly genetic adaptations to local environmental conditions. Our findings provided references for the conservation and sustainable utilization of JC goats.

Brown adipose tissue (BAT) is an important component of energy expenditure and necessary to maintain body temperature for newborn mammals. In the previous study, we found that L‐carnitine was enriched in BAT and promoted BAT adipogenesis and thermogenesis in goat brown adipocytes. However, whether dietary L‐carnitine regulates BAT heat production and energy expenditure in lambs remains unclear. In this study, maternal L‐carnitine supplementation elevated the rectal temperature, as well as the expression of UCP1 and mitochondrial DNA content to promote BAT thermogenesis in newborn goats. Moreover, maternal L‐carnitine supplementation increased the levels of triglycerides (TG), non‐esterified fatty acids (NEFA), and lactate in plasma, as well as the content of lipid droplet and glycogen in BAT of newborn goats. Lipidomic analysis showed that maternal L‐carnitine supplementation remodeled the lipid composition of BAT in newborn goats. L‐carnitine significantly increased the levels of TG and diglyceride (DG) and decreased the levels of glycerophospholipids and sphingolipids in BAT. Further studies showed that L‐carnitine promoted TG and glycogen deposition in brown adipocytes through AMPKα. Our results indicate that maternal L‐carnitine supplementation promotes BAT development and thermogenesis in newborn goats and provides new evidence for newborn goats to maintain body temperature in response to cold exposure.

As a well-known cancer-related miRNA, miR-193b-3p is enriched in skeletal muscle and dysregulated in muscle disease. However, the mechanism underpinning this has not been addressed so far. Here, we probed the impact of miR-193b-3p on myogenesis by mainly using goat tissues and skeletal muscle satellite cells (MuSCs), compared with mouse C2C12 myoblasts. miR-193b-3p is highly expressed in goat skeletal muscles, and ectopic miR-193b-3p promotes MuSCs proliferation and differentiation. Moreover, insulin-like growth factor-2 mRNA-binding protein 1 (IGF2BP1) is the most activated insulin signaling gene when there is overexpression of miR-193b-3p; the miRNA recognition element (MRE) within the IGF1BP1 3′ untranslated region (UTR) is indispensable for its activation. Consistently, expression patterns and functions of IGF2BP1 were similar to those of miR-193b-3p in tissues and MuSCs. In comparison, ectopic miR-193b-3p failed to induce PAX7 expression and myoblast proliferation when there was IGF2BP1 knockdown. Furthermore, miR-193b-3p destabilized IGF2BP1 mRNA, but unexpectedly promoted levels of IGF2BP1 heteronuclear RNA (hnRNA), dramatically. Moreover, miR-193b-3p could induce its neighboring genes. However, miR-193b-3p inversely regulated IGF2BP1 and myoblast proliferation in the mouse C2C12 myoblast. These data unveil that goat miR-193b-3p promotes myoblast proliferation via activating IGF2BP1 by binding to its 3′ UTR. Our novel findings highlight the positive regulation between miRNA and its target genes in muscle development, which further extends the repertoire of miRNA functions.