Project description:Background : The Blonde Aquitaine (BA) is a French beef breed with enhanced muscularity of unknown genetic origin. Targeted sequencing has shown that the BA is not a carrier of any of the bovine MSTN mutations. At the protein level the BA shows a transition to a faster muscle isoform phenotype with a greater proportion of type IIX and a smaller proportion of type I fibres than comparison Charolais (CH). Associated modifications in the activity of oxidative and glycolytic enzymes were also previously detected. Collectively, these changes are often observed in breeds of production species selected for enhanced growth and efficiency, but the underlying molecular mechanisms are unknown. Method : We examined the transcriptome of the Longissimus thoracis muscle at 4 gestational stages (110, 180, 210, and 260 dpc) in BA and CH foetuses. These time points coincide with primary and secondary myogenesis and functional differentiation. Total RNA was hybridised to the Agilent one-colour microarray platform containing 45,220 probes mapped to 17646 protein coding bovine genes. Following normalisation, we used a combination of differential expression (limma method, Smyth & al 2005) and a network theory method based on differential co-expression analysis (Hudson & al 2009) to compare and contrast the two muscle transcriptomes. Conclusions : In both breeds the most developmentally-regulated genes included: embryonic muscle subunit isoforms (e.g. MYL4) whose expression dropped dramatically prior to birth when they are replaced by the adult isoforms; metabolic enzymes (e.g. the mitochondrially-localised sarcomeric creatine kinase CKMT2) that prepare the foetus for functional independence postpartum, and 1 probe out of 4 representing a gene of unknown function (C13H20ORF194) also previously published as highly developmentally regulated in Wagyu by Hereford longissimus muscle (Hudson & al 2013). In contrasting the breeds, MSTN was the 2nd most differentially expressed muscle gene between the breeds, being approximately 4-fold down-regulated in CH at each of the time points. Given MSTN is a growth inhibitor, this result may reflect either divergent muscle mass or fibre composition in foetuses and could account for the low muscle development of BA calves at birth. Among the most differentially connected transcriptional regulators we prioritised expected molecules like MSTN, but also unexpected ones like PROX1, NMI, MBD1, NRIP2 and TAF12. Although not differentially expressed at the transcript level these molecules are transcriptionally rewired between the breeds and may form attractive new candidates for the development of differential muscle mass and fibre composition in cattle.

Project description:Background : The Blonde Aquitaine (BA) is a French beef breed with enhanced muscularity of unknown genetic origin. Targeted sequencing has shown that the BA is not a carrier of any of the bovine MSTN mutations. At the protein level the BA shows a transition to a faster muscle isoform phenotype with a greater proportion of type IIX and a smaller proportion of type I fibres than comparison Charolais (CH). Associated modifications in the activity of oxidative and glycolytic enzymes were also previously detected. Collectively, these changes are often observed in breeds of production species selected for enhanced growth and efficiency, but the underlying molecular mechanisms are unknown. Method : We examined the transcriptome of the Longissimus thoracis muscle at 4 gestational stages (110, 180, 210, and 260 dpc) in BA and CH foetuses. These time points coincide with primary and secondary myogenesis and functional differentiation. Total RNA was hybridised to the Agilent one-colour microarray platform containing 45,220 probes mapped to 17646 protein coding bovine genes. Following normalisation, we used a combination of differential expression (limma method, Smyth & al 2005) and a network theory method based on differential co-expression analysis (Hudson & al 2009) to compare and contrast the two muscle transcriptomes. Conclusions : In both breeds the most developmentally-regulated genes included: embryonic muscle subunit isoforms (e.g. MYL4) whose expression dropped dramatically prior to birth when they are replaced by the adult isoforms; metabolic enzymes (e.g. the mitochondrially-localised sarcomeric creatine kinase CKMT2) that prepare the foetus for functional independence postpartum, and 1 probe out of 4 representing a gene of unknown function (C13H20ORF194) also previously published as highly developmentally regulated in Wagyu by Hereford longissimus muscle (Hudson & al 2013). In contrasting the breeds, MSTN was the 2nd most differentially expressed muscle gene between the breeds, being approximately 4-fold down-regulated in CH at each of the time points. Given MSTN is a growth inhibitor, this result may reflect either divergent muscle mass or fibre composition in foetuses and could account for the low muscle development of BA calves at birth. Among the most differentially connected transcriptional regulators we prioritised expected molecules like MSTN, but also unexpected ones like PROX1, NMI, MBD1, NRIP2 and TAF12. Although not differentially expressed at the transcript level these molecules are transcriptionally rewired between the breeds and may form attractive new candidates for the development of differential muscle mass and fibre composition in cattle. 2 beef breeds: Blond Aquitaine (BA) and Charolais (CH) ; 4 gestational stages per breed (110, 180, 210, and 260 dpc); 3 animals (biological replicats) per stage and per breed, except for BA 180 dpc, BA 260 dpc and CH 110 dpc (only 2 animals due to technical problem during hybridization).

Project description:BACKGROUND: The muscle fiber number and fiber composition of muscle is largely determined during prenatal development. In order to discover genes that are involved in determining adult muscle phenotypes, we studied the gene expression profile of developing fetal bovine longissimus muscle from animals with two different genetic backgrounds using a bovine cDNA microarray. Fetal longissimus muscle was sampled at 4 stages of myogenesis and muscle maturation: primary myogenesis (d 60), secondary myogenesis (d 135), as well as beginning (d 195) and final stages (birth) of functional differentiation of muscle fibers. All fetuses and newborns (total n = 24) were from Hereford dams and crossed with either Wagyu (high intramuscular fat) or Piedmontese (GDF8 mutant) sires, genotypes that vary markedly in muscle and compositional characteristics later in postnatal life. RESULTS: We obtained expression profiles of three individuals for each time point and genotype to allow comparisons across time and between sire breeds. Quantitative reverse transcription-PCR analysis of RNA from developing longissimus muscle was able to validate the differential expression patterns observed for a selection of differentially expressed genes, with one exception. We detected large-scale changes in temporal gene expression between the four developmental stages in genes coding for extracellular matrix and for muscle fiber structural and metabolic proteins. FSTL1 and IGFBP5 were two genes implicated in growth and differentiation that showed developmentally regulated expression levels in fetal muscle. An abundantly expressed gene with no functional annotation was found to be developmentally regulated in the same manner as muscle structural proteins. We also observed differences in gene expression profiles between the two different sire breeds. Wagyu-sired calves showed higher expression of fatty acid binding protein 5 (FABP5) RNA at birth. The developing longissimus muscle of fetuses carrying the Piedmontese mutation shows an emphasis on glycolytic muscle biochemistry and a large-scale up-regulation of the translational machinery at birth. We also document evidence for timing differences in differentiation events between the two breeds. CONCLUSION: Taken together, these findings provide a detailed description of molecular events accompanying skeletal muscle differentiation in the bovine, as well as gene expression differences that may underpin the phenotype differences between the two breeds. In addition, this study has highlighted a non-coding RNA, which is abundantly expressed and developmentally regulated in bovine fetal muscle.

Dataset Information

Molecular regulation of high muscle mass in developing Blonde d'Aquitaine cattle foetuses.

Publications

Molecular regulation of high muscle mass in developing Blonde d'Aquitaine cattle foetuses.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets