How Genes and Epigenetics Shape Muscle Growth in Young Chickens

Jenn Hoskins
6th July, 2024

How Genes and Epigenetics Shape Muscle Growth in Young Chickens

During the 42-day postnatal period, Cornish (CC) broilers demonstrated superior growth in body and pectoral muscle weight compared to White Plymouth Rock (RR) broilers (a, b), a phenotype driven by muscle fiber hypertrophy (cā€“f) that provides the basis for the study's subsequent molecular investigation into rapid muscle development at key stages (g).

Image adapted from: Gu et al. / CC BY (Source)

Key Findings

  • The study, conducted at China Agricultural University, focused on muscle development in two broiler breeds, Cornish (CC) and White Plymouth Rock (RR), over a 42-day period
  • Researchers identified key genes and regulatory elements that are differentially expressed and accessible between day 21 (D21) and day 42 (D42), which are crucial stages for broiler growth
  • The study found that rapid muscle growth in broilers involves continuous muscle damage and subsequent regeneration, highlighting the roles of genes like ACTC1, FDPS, NRG1, TGFB3, MUSTN1, and FOS
Broilers are a key component of global meat production, known for their rapid growth rates. Despite their economic importance, the molecular and epigenetic mechanisms that drive this rapid growth are not fully understood. A recent study conducted by researchers at China Agricultural University aims to shed light on these mechanisms by exploring muscle development patterns and regulatory networks during the postnatal rapid growth phase of fast-growing broilers[1]. The study focused on two breeds of broilers, Cornish (CC) and White Plymouth Rock (RR), over a 42-day period. Researchers collected pectoral muscle samples at two critical time points, day 21 (D21) and day 42 (D42) post-hatching, for RNA sequencing (RNA-seq) and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) to understand gene expression and chromatin accessibility, respectively. Previous research has highlighted the importance of muscle fiber characteristics in meat quality and growth performance in broilers[2]. For instance, a study comparing Xueshan chickens (slow-growing) and Ross 308 broilers (fast-growing) found significant differences in muscle fiber density and glycolytic potential (GP) at just one day old. The fast-growing Ross 308 broilers exhibited lower fiber density and higher GP, indicating a predisposition for rapid muscle growth. This earlier study provides a foundational understanding of how muscle characteristics can influence growth rates and meat quality in broilers. The new study delved deeper into the molecular mechanisms by using advanced genomic techniques. RNA-seq allows researchers to measure the expression levels of thousands of genes simultaneously, providing a comprehensive view of the genetic activity in the muscle tissues. ATAC-seq, on the other hand, identifies regions of open chromatin, which are accessible to transcription factors and other regulatory proteins, thereby offering insights into the regulatory networks controlling gene expression. One of the significant findings of the new study was the identification of key genes and regulatory elements that are differentially expressed and accessible between D21 and D42 in both CC and RR breeds. These genes are involved in various biological processes, including muscle cell proliferation, differentiation, and metabolism. This aligns with previous findings that highlighted the role of growth and differentiation factors in muscle development[3]. For example, the administration of diamond nanoparticles combined with L-glutamine in fertilized broiler eggs has been shown to up-regulate genes related to muscle cell proliferation (FGF2) and differentiation (MyoD1), enhancing muscle growth and maturation. The new study also builds on our understanding of muscle regeneration and the role of satellite cells, which are essential for muscle repair and growth[4]. Satellite cells are muscle stem cells that can proliferate and differentiate to form new muscle fibers. The dynamic interplay between intrinsic factors within satellite cells and extrinsic factors in their microenvironment is crucial for muscle regeneration. The identification of regulatory networks in the current study provides new insights into how these processes are controlled at the molecular level in fast-growing broilers. In summary, the research conducted by China Agricultural University significantly advances our understanding of the molecular and epigenetic mechanisms driving rapid muscle growth in broilers. By integrating RNA-seq and ATAC-seq data, the study identifies key genes and regulatory elements involved in muscle development, offering potential targets for improving growth performance and meat quality in broilers. This study not only corroborates earlier findings on muscle fiber characteristics and growth factors but also provides a more detailed molecular framework for future research and practical applications in poultry farming.

GeneticsBiochemAnimal Science

References

Main Study

1) Transcriptomic and epigenomic landscapes of muscle growth during the postnatal period of broilers

Published 4th July, 2024

https://doi.org/10.1186/s40104-024-01049-w

Related Studies

2) Comparison of muscle fiber characteristics and glycolytic potential between slow- and fast-growing broilers.

https://doi.org/10.1016/j.psj.2021.101649

3) Nano-nutrition of chicken embryos. The effect of in ovo administration of diamond nanoparticles and L-glutamine on molecular responses in chicken embryo pectoral muscles.

https://doi.org/10.3390/ijms141123033

4) Satellite cells and the muscle stem cell niche.

https://doi.org/10.1152/physrev.00043.2011


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