Structure and function analyses of the Mmd2 gene in pacific white shrimp Litopenaeus vannamei

Monocyte to macrophage differentiation factor 2 gene (Mmd2) encodes a member of the progestin and adipoQ receptor (PAQR) family, and plays a key role in growth and development. Our previous studies had found Mmd2 (Monocyte to macrophage differentiation factor 2) is a new candidate gene for growth traits in Pacific white shrimp (Litopenaeus vannamei). For the purpose of understanding the underlying mechanism of LvMmd2 affecting the growth of shrimp, we analyzed the gene structure, phylogeny, expression profiles and RNA interference of this gene in L. vannamei. We found the LvMmd2 gene sequence was highly conserved in transmembrane regions, it was widely expressed in different tissues, with the highest expression level in the eye stalk. Knockdown LvMmd2 could significantly promote body length and body weight gain, suggesting it is a growth suppressor. Through transcriptome analysis we identified 422 differentially expressed genes (DEGs) between the dsMmd2 group and control group, among which 337 genes were upregulated in the dsMmd2 group, including numerous muscle-related genes and protein synthesis genes. Further bioinformatics analysis showed that growth, metabolism, and immune-related signal pathway had changed significantly. The above results greatly increase our understanding on the conservative structure and function of LvMmd2 gene, and provide potential application prospects in genetics and breeding.

Automated summary

Considering the important role of Monocyte to macrophage differentiation factor 2 gene (Mmd2) in growth and development, we analyzed the gene structure, expression profiles, and RNA interference of LvMmd2 in L. vannamei. LvMmd2 gene sequence was found to be highly conserved in transmembrane regions and widely expressed in different tissues, with the highest expression level in the eye stalk. Knockdown of LvMmd2 significantly promoted body length and body weight gain, indicating its role as a growth suppressor. Transcriptome analysis revealed significant changes in growth, metabolism, and immune-related signal pathways. These results enhance our understanding of the conservative structure and function of LvMmd2 gene and have potential applications in genetics and breeding.