Abstract:  In poultries, muscle growth is a quantitative trait controlled by multiple genes. The regulatory mechanisms governing muscle tissue growth and develop ment in poultry, particularly during the early stages of growth, are intricate. Through the examination of leg muscle transcripts from Yili geese during various stages of development, this study offers valuable insights into the molecular mechanisms underlying the growth and development of Yili geese. This study aimed to perform a comparative analysis of the histological characteristics of leg muscles and the mRNA expression profiles of leg muscles in Yili geese at different ages (2, 4, 6, 8, and 10 wk). The objective was to identify differentially expressed genes related to muscle development in Yili geese and utilize bioinformatics to predict the potential biological functions of these genes. Through histological studies on leg muscle tissues, it was discerned that male geese at 4 wk exhibit a significantly reduced muscle fiber density in comparison to females (P < 0.01). In contrast, by the time they reach 6, 8, and 10 wk, their muscle fiber diameter and cross-sectional dimensions significantly outpace the females (P < 0.01). With the advancement in age, muscle fiber density tends to decrease. It is worth noting that 4- and 6-wk-old male geese have a substantially elevated muscle fiber density when matched against females (P < 0.01). Conversely, at the age of 10 wk, their muscle fiber density is notably inferior to the females (P < 0.01). Furthermore, male geese exhibit the most rapid increase in muscle fiber diameter and cross-sectional area between 4 and 6 wk of age. The density of muscle fibers in these geese significantly decreases from 4 to 8 wk. In contrast, female geese show the most pronounced growth in muscle fiber diameter and cross-sectional area between 2 and 6 wk, with a swift decline in density following the 6-wk mark, accompanied by a gradual reduction in the rate of muscle fiber growth. A comprehensive analysis of the leg muscle mRNA expression profiles from 12 Yili geese generated a cumulative total of 502,065,268 valid sequence reads, corresponding to a data volume of 75.30 Gb. In a comparative analysis between 4-wk-old and 2-wk-old groups (T4 vs. T2), 8-wk-old and 2-wk-old groups (T8 vs. T2), and 8-wk-old and 4-wk-old groups (T8 vs. T4), we identified 1,700, 1,583, and 221 differentially expressed genes (DEGs), respectively. Differentially expressed genes were signifi-cantly enriched in Gene Ontology (GO) terms such as organelle organization, cytoskeletal protein binding, cation transport, myosin complex, and actin cytoskeleton. Among the significantly enriched signaling pathways, 5 pathways were found to be significantly related to growth and development: adhesion patch, extracellular matrix receptor interaction, tight junction, TGF-β signaling pathway, and MAPK signaling pathway, with a total of 38 differentially differentiated genes contained in these 5 pathways, and it was hypothesized that the above pathways as well as the DEGs in  he pathways played an important role in the regulation of early growth and development of the Yili goose. This investigation serves as a foundational reference for elucidating the molecular regulatory mechanisms involved in the development of goose muscle. Furthermore, it contributes to the expansion of the theoretical framework concerning the genetic regulation of muscle growth in geese.

Keywords:  mRNA, goose, leg muscles, growth

Development of myofibers and muscle transcriptomic analysis in growing Yili geese.pdf