Transcriptome response of proliferating muscle satellite cells to thermal challenge in commercial turkey

Genome-wide association study to identify biological and metabolic pathways associated with carcass portion weights in turkeys: GWAS OF TURKEY CARCASS PORTION WEIGHTS

The application of genetic and genomic improvement strategies in the poultry industry has been widely successful at improving meat yield and efficiency, however some challenges persist. As demand for larger and leaner birds increases, we have not fully assessed how selection for growth affects various carcass portions. The objective of this study was to conduct a genome wide association study (GWAS) and functional analysis on turkey carcass portion weights. Phenotypic data consisted of carcass portion weights (fillets, tenders, drums, thighs) obtained at processing (N = 646 - 1,478). Genotypic records were available from a proprietary 65 K single nucleotide polymorphism (SNP) chip. A linear mixed model was used to estimate SNP effects and a 30-SNP sliding window approach was used. Across all traits, 14 functional candidate genes (FCGs) were identified, and these were predominately associated with protein metabolism and immune function. Interestingly, carcass portions did not share FCGs, except for the thighs and drums, which shared one functional candidate gene (PDGFB). These results add to the understanding of the genetic architecture of carcass portion weights, and this could be applied in a turkey breeding program.

Molecular characterization of the heterogeneity of satellite cell populations isolated from an individual Turkey pectoralis major muscle

Satellite cells (SCs) are myogenic stem cells responsible for post hatch muscle growth and the regeneration of muscle fibers. Satellite cells are not a homogenous population of cells within a muscle and have variable rates of proliferation and differentiation even within a single fiber type muscle like the turkey pectoralis major muscle. In this study, the single satellite cell clones derived from the same turkey pectoralis major muscle with different proliferation rates were compared. The clones were classified as either fast-growing (early clone) or slow-growing (late clone) SCs. To thoroughly examine the molecular differences between these two groups, RNA sequencing was conducted to compare their transcriptomes following 72 h of proliferation. Principal Component Analysis confirmed that the transcriptomic profiles of early- and late-clones are markedly distinct. Differential gene expression analysis identified over 5,300 genes that were significantly differentially expressed between the two groups of cells. Gene ontology analysis showed that genes highly expressed in early clones are responsible for the fundamental aspects of muscle biology, including muscle tissue development and structural maturation. Conversely, genes upregulated in late clones are involved in cell-cell communication, extracellular matrix interactions, signal ligand activity, and cytokine activity-key components for forming an extracellular niche essential for functional satellite cells maintenance. Further examination of specific gene ontology categories such as muscle structure development and extracellular matrix components indicated significant differences in gene expression patterns between early- and late-clones. These findings highlight the genetic and functional diversity of SCs in turkeys. The distinct roles of these satellite cell populations indicate that a balance between them is necessary for preserving the normal physiological functions of SCs.

Integrated Genomic Approaches to Characterize and Mitigate Heat Stress in Poultry

With the burgeoning human population, climate change, and expansion of poultry production in hot climates, it is imperative to aid global food security by enhancing the resilience of thermally challenged poultry. As a complement to management approaches used to mitigate heat stress, we give selected examples of recent studies on heat stress in poultry using various omics technologies. An integrated analysis of positional and functional candidate genes is provided, highlighting the most prominent pathways involved in the heat stress response. We finish by discussing efficient strategies to enhance thermal tolerance of poultry by genomics approaches, advocating for preservation of biodiversity that may provide beneficial allelic variation, and identifying current and future challenges in producing climate-resilient poultry.

Circular RNA expression in turkey skeletal muscle satellite cells is significantly altered by thermal challenge

Introduction

Understanding the genetic mechanisms behind muscle growth and development is crucial for improving the efficiency of animal protein production. Recent poultry studies have identified genes related to muscle development and explored how environmental stressors, such as temperature extremes, affect protein production and meat quality. Non-coding RNAs, including circular RNAs (circRNAs), play crucial roles in modulating gene expression and regulating the translation of mRNAs into proteins. This study examined circRNA expression in turkey skeletal muscle stem cells under thermal stress. The objectives were to identify and quantify circRNAs, assess circRNA abundance following RNAse R depletion, identify differentially expressed circRNAs (DECs), and predict potential microRNA (miRNA) targets for DECs and their associated genes.

Materials and methods

Cultured cells from two genetic lines (Nicholas commercial turkey and The Ohio State Random Bred Control 2) under three thermal treatments: cold (33°C), control (38°C), and hot (43°C) were compared at both the proliferation and differentiation stages. CircRNA prediction and differential expression and splicing analyses were conducted using the CIRIquant pipeline for both the untreated and RNase R depletion treated libraries. Predicted interactions between DECs and miRNAs, as well as the potential impact of circRNA secondary structure on these interactions, were investigated.

Results

A total of 11,125 circRNAs were predicted within the treatment groups, between both untreated and RNase R treated libraries. Differential expression analyses indicated that circRNA expression was significantly altered by thermal treatments and the genetic background of the stem cells. A total of 140 DECs were identified across the treatment comparisons. In general, more DECs within temperature treatment comparisons were identified in the proliferation stage and more DECs within genetic line comparisons were identified in the differentiation stage.

Discussion

This study highlights the significant impact of environmental stressors on non-coding RNAs and their role in gene regulation. Elucidating the role of non-coding RNAs in gene regulation can help further our understanding of muscle development and poultry production, underscoring the broader implications of this research for enhancing animal protein production efficiency.

Transcriptome Response of Differentiating Muscle Satellite Cells to Thermal Challenge in Commercial Turkey

Early muscle development involves the proliferation and differentiation of stem cells (satellite cells, SCs) in the mesoderm to form multinucleated myotubes that mature into muscle fibers and fiber bundles. Proliferation of SCs increases the number of cells available for muscle formation while simultaneously maintaining a population of cells for future response. Differentiation dramatically changes properties of the SCs and environmental stressors can have long lasting effects on muscle growth and physiology. This study was designed to characterize transcriptional changes induced in turkey SCs undergoing differentiation under thermal challenge. Satellite cells from the pectoralis major (p. major) muscle of 1-wk old commercial fast-growing birds (Nicholas turkey, NCT) and from a slower-growing research line (Randombred Control Line 2, RBC2) were proliferated for 72 h at 38 °C and then differentiated for 48 h at 33 °C (cold), 43 °C (hot) or 38 °C (control). Gene expression among thermal treatments and between turkey lines was examined by RNAseq to detect significant differentially expressed genes (DEGs). Cold treatment resulted in significant gene expression changes in the SCs from both turkey lines, with the primary effect being down regulation of the DEGs with overrepresentation of genes involved in regulation of skeletal muscle tissue regeneration and sarcomere organization. Heat stress increased expression of genes reported to regulate myoblast differentiation and survival and to promote cell adhesion particularly in the NCT line. Results suggest that growth selection in turkeys has altered the developmental potential of SCs in commercial birds to increase hypertrophic potential of the p. major muscle and sarcomere assembly. The biology of SCs may account for the distinctly different outcomes in response to thermal challenge on breast muscle growth, development, and structure of the turkey.