Polymorphisms of four candidate genes and their correlations with growth traits in blue fox (Alopex lagopus)

Cloning, distribution, and effects of growth regulation of MC3R and MC4R in red crucian carp (Carassius auratus red var.)

Background

Melanocortin-3 and -4 receptors (MC3R and MC4R), G protein-coupled receptors, play vital roles in the regulation of energy homeostasis. To understand the functions of mc3r and mc4r in the energy homeostasis of red crucian carp (Carassius auratus red var., RCC), we cloned mc3r and mc4r, analyzed the tissue expression and localization of the genes, and investigated the effects of knockout of mc3r (mc3r +/-) and mc4r (mc4r +/-) in RCC.

Results

The full-length cDNAs of RCC mc3r and mc4r were 1459 base pairs (bp) and 1894 bp, respectively. qRT-PCR indicated that mc3r and mc4r were profusely expressed in the brain, but lower expressed in the periphery tissues. ISH revealed that mc3r and mc4r were located in NPP, NPO, NAPv, NSC, NAT, NRL, NLTl, and NLTp of the brain, suggesting that mc3r and mc4r might regulate many physiological and behavioral aspects in RCC. To further verify the roles of mc3r and mc4r in energy homeostasis, the mc3r+/- and mc4r+/- fish were obtained by the CRISPR/Cas9 system. The average body weights, total lengths, body depths, and food intake of mc4r+/- fish were significantly higher than those of mc3r+/- and the normal wild-type (WT) fish, but there was no difference between the mc3r+/- and WT fish, indicating that the RCC phenotype and food intake were mainly influenced by mc4r but not mc3r. Interestingly, mc4r+/- fish displayed more visceral fat mass than mc3r+/- and WT fish, and mc3r+/- fish also exhibited slightly more visceral fat mass compared to WT. RNA-seq of the liver and muscle revealed that a large number of differentially expressed genes (DEGs) differed in WT vs. mc3r+/-, WT vs. mc4r+/-, and mc3r+/- vs. mc4r+/-, mainly related to lipid, glucose, and energy metabolism. The KEGG enrichment analysis revealed that DEGs were mainly enriched in pathways such as steroid biosynthesis, fatty acid metabolism, fatty acid biosynthesis, glycolysis/gluconeogenesis, wnt signaling pathway, PPAR signaling pathway, and MAPK signaling pathway, thereby affecting lipid accumulation and growth.

Conclusion

In conclusion, these results will assist in the further investigation of the molecular mechanisms in which MC3R and MC4R were involved in the regulation of energy homeostasis in fish.

Mutations in melanocortin-4 receptor: From fish to men

Melanocortin-4 receptor (MC4R), expressed abundantly in the hypothalamus, is a critical regulator of energy homeostasis, including both food intake and energy expenditure. Shortly after the publication in 1997 of the Mc4r knockout phenotypes in mice, including increased food intake and severe obesity, the first mutations in MC4R were reported in humans in 1998. Studies in the subsequent two decades have established MC4R mutation as the most common monogenic form of obesity, especially in early-onset severe obesity. Studies in animals, from fish to mammals, have established the conserved physiological roles of MC4R in all vertebrates in regulating energy balance. Drug targeting MC4R has been recently approved for treating morbid genetic obesity. How the MC4R can be exploited for animal production is highly worthy of active investigation.

Integrative Genome-Wide DNA Methylome and Transcriptome Analysis of Ovaries from Hu Sheep with High and Low Prolific

DNA methylation plays an important role in biological processes by affecting gene expression. However, how DNA methylation regulates phenotypic variation in Hu sheep remains unclear. Therefore, we generated genome-wide DNA methylation and transcriptomic profiles in the ovaries of Hu sheep with different prolificacies and genotypes (FecBB and FecB+). Results showed that ovary DNA methylome and transcriptome were significantly different between high prolificacy and low prolificacy Hu sheep. Comparative methylome analyses identified 10,644, 9,594, and 12,214 differentially methylated regions and 87, 1,121, and 2,375 genes, respectively, showing differential expression levels in three different comparison groups. Female reproduction-associated differentially methylated regions-related genes and differentially expressed genes were enriched, thereby the respective interaction networks were constructed. Furthermore, systematical integrative analyses revealed a negative correlation between DNA methylation around the transcriptional start site and gene expression levels, which was confirmed by testing the expression of integrin β2 subunit (ITGB2) and lysosome-associated protein transmembrane-4 beta (LAPTM4B) in vivo and in vitro. These findings demonstrated that DNA methylation influences the propensity for prolificacy by affecting gene expression in the ovaries, which may contribute to a greater understanding of the epigenome and transcriptome that will be useful for animal breeding.

Genome-wide association studies for growth traits in broilers

BACKGROUND

The identification of markers and genes for growth traits may not only benefit for marker assist selection /genomic selection but also provide important information for understanding the genetic foundation of growth traits in broilers.

RESULTS

In the current study, we estimated the genetic parameters of eight growth traits in broilers and carried out the genome-wide association studies for these growth traits. A total of 113 QTNs discovered by multiple methods together, and some genes, including ACTA1, IGF2BP1, TAPT1, LDB2, PRKCA, TGFBR2, GLI3, SLC16A7, INHBA, BAMBI, APCDD1, GPR39, and GATA4, were identified as important candidate genes for rapid growth in broilers.

CONCLUSIONS

The results of this study will provide important information for understanding the genetic foundation of growth traits in broilers.