Viscera Characteristics of MSTN-Edited Heterozygous Pigs.

Yangli Pei,Yulian Mu,Zheng Feng,Hua Li,Bugao Li,Yuxin Song,Chujie Chen,Kui Li,Ziyao Fan

doi:10.3389/fgene.2022.764965

Abstract

Myostatin (MSTN) is a protein that negatively regulates growth of skeletal muscle, and inactivation of MSTN improves the mass of skeletal muscle. Our previous work found that MSTN +/− pigs have higher muscle depth and lower fat depth compared to wild type without any developmental problems. Therefore, MSTN-edited pigs are most likely to appear as heterozygotes in the potential future market, but the characteristics of organs in digestive and reproductive system of pigs with MSTN gene editing remains unclear. Here, we investigated the histological of the organs in the digestive system and reproductive system in MSTN gene heterozygotes at adult stages. The length of intestine was further compared between adult heterozygous and wild type pigs. We found no significant differences in histomorphology of organs, including heart, duodenum, jejunum, ileum, cecum, colon, testis, epididymis, ovaries, oviducts and uterus, between individuals from two genotypes. Moreover, there was no significant difference in the average length of intestine in adult pigs. Our data provide a reference for further clarifying the applications of MSTN gene edited pigs.

Highlights

The formalin-fixed paraffin-embedded heart tissue of MSTN+/− and wild type (WT) piglets were stained by Hematoxylin and Eosin (H&E) for histomorphological comparison
Results showed that the myocardial fibers of newborn WT and MSTN pigs were both short and cylindrical, branched and interconnected in a network, and there were intercalated discs at the junction between adjacent myocardial fibers (Figures 1A,B)
Knockout Large White/Landrace×Duroc piglets died within 24 h after birth, and weighed less at birth than WT piglets

Summary

Introduction

In 1997, McPherron first identified MSTN ( known as growth differentiation factor-8) as a member of the TGF-β (transforming growth factor-β) superfamily (McPherron et al, 1997). The MSTN mutation lead to a double muscling phenotype in cattle (Grobet et al, 1997; McPherron and Lee, 1997), mice (Bünger et al, 2004), sheep (Clop et al, 2006) and other animals (Schuelke et al, 2004; Mosher et al, 2007). Luo (2019) examined the organ weights of MSTN−/−, MSTN+/− and WT piglets and found that the visceral weight of MSTN−/− homozygous piglets was significantly lower than that of MSTN+/− heterozygotes and WT piglets (Luo et al, 2019) These studies show that animals with double site knockout of MSTN have lighter internal organs than WT individuals. The mechanism of how MSTN regulates visceral development remains unclear These findings all raise concerns about the health and welfare of MSTN edited animals

Methods

Results

Conclusion