Project description:Background: Weaning of beef calves is a necessary husbandry practice and involves separating the calf from its mother, resulting in numerous stressful events including dietary change, social reorganisation and the cessation of the maternal-offspring bond and is often accompanied by housing. While much recent research has focused on the physiological response of the bovine immune system to stress in recent years, little is known about the molecular mechanisms modulating the immune response. Therefore, the objective of this study was to provide new insights into the molecular mechanisms underlying the physiological response to weaning at housing in beef calves using Illumina RNA-seq. Results: The leukocyte transcriptome was significantly altered for at least 7 days following either housing or weaning at housing. Analysis of differentially expressed genes revealed that four main pathways, cytokine signalling, transmembrane transport, haemostasis and G-protein-coupled receptor (GPRC) signalling, were differentially regulated between control and weaned calves and underwent significant transcriptomic alterations in response to weaning stress on day 1, 2 and 7. Of particular note, chemokines, cytokines and integrins were consistently found to be up-regulated on each day following weaning. Evidence for alternative splicing of genes was also detected, indicating that a number of genes involved in the innate and adaptive immune response may be alternatively transcribed, including those responsible for toll receptor cascades and T cell receptor signalling. Conclusions: This study represents the first application of RNA-Seq technology for genomic studies in bovine leukocytes in response to weaning stress. Weaning stress induces the activation of a number of cytokine, chemokine and integrin transcripts and may alter the immune system whereby the ability of a number of cells of the innate and adaptive immune system to locate and destroy pathogens is transcriptionally enhanced. Stress alters the homeostasis of the transcriptomic environment of leukocytes for at least 7 days following weaning, indicating long-term effects of stress exposure in the bovine. The identification of gene signature networks that are stress activated provides a mechanistic framework to characterise the multifaceted nature of weaning stress adaptation in beef calves. Thus, capturing subtle transcriptomic changes provides insight into the molecular mechanisms that underlie the physiological response to weaning stress. Examination of a time course (day 0, 1, 2 and 7) for 2 treatments, calves either housed with their dam (control) or housed and simultaneously weaned, using RNA-seq. The supplementary processed data file 'read_counts.txt' contains unnormalized read counts for each Ensembl bovine gene in each of the 48 samples. Unnormalized counts are required for input to EdgeR. Genome build: Btau4.0

Project description:Background: Weaning of beef calves is a necessary husbandry practice and involves separating the calf from its mother, resulting in numerous stressful events including dietary change, social reorganisation and the cessation of the maternal-offspring bond and is often accompanied by housing. While much recent research has focused on the physiological response of the bovine immune system to stress in recent years, little is known about the molecular mechanisms modulating the immune response. Therefore, the objective of this study was to provide new insights into the molecular mechanisms underlying the physiological response to weaning at housing in beef calves using Illumina RNA-seq. Results: The leukocyte transcriptome was significantly altered for at least 7 days following either housing or weaning at housing. Analysis of differentially expressed genes revealed that four main pathways, cytokine signalling, transmembrane transport, haemostasis and G-protein-coupled receptor (GPRC) signalling, were differentially regulated between control and weaned calves and underwent significant transcriptomic alterations in response to weaning stress on day 1, 2 and 7. Of particular note, chemokines, cytokines and integrins were consistently found to be up-regulated on each day following weaning. Evidence for alternative splicing of genes was also detected, indicating that a number of genes involved in the innate and adaptive immune response may be alternatively transcribed, including those responsible for toll receptor cascades and T cell receptor signalling. Conclusions: This study represents the first application of RNA-Seq technology for genomic studies in bovine leukocytes in response to weaning stress. Weaning stress induces the activation of a number of cytokine, chemokine and integrin transcripts and may alter the immune system whereby the ability of a number of cells of the innate and adaptive immune system to locate and destroy pathogens is transcriptionally enhanced. Stress alters the homeostasis of the transcriptomic environment of leukocytes for at least 7 days following weaning, indicating long-term effects of stress exposure in the bovine. The identification of gene signature networks that are stress activated provides a mechanistic framework to characterise the multifaceted nature of weaning stress adaptation in beef calves. Thus, capturing subtle transcriptomic changes provides insight into the molecular mechanisms that underlie the physiological response to weaning stress.

Project description:An abrupt transition from high forage to high fermentable diet may induce digestive disorders in the rumen. To date, the host mechanisms regulate the adaption to such dietary transition are largely unknown. To understand the molecular mechanisms involved in such phenomena, RNA-sequencing was performed to identify the changes in the transcriptomes of ruminal epithelia during a rapid high grain transition from 3% to 92% grain. In total, the expression of 11,044, 11,322 and 11,282 genes was detected in ruminal epithelia of beef heifers (n=15) fed 3%, 75% and 92% barley grain diet, respectively. When diet was changed from 75% to 92% grain, a significant difference was observed in the mean ruminal pH change among the individuals with five heifers decreased (DG; pH from 6.30 ± 0.09 to 5.87 ± 0.15, P < 0.01) and five other ones increased (UG; pH from 5.84 ± 0.42 to 6.35 ± 0.37, P < 0.05). In the ruminal epithelia of DG animals, the expression of genes involved in ketogenesis (HMGCL, P < 0.1) and lipid synthesis (SREBF2, P < 0.1; FABP4, P < 0.05) was increased, the abundance of genes involved in short chain fatty acid transporters (SMCT1, P < 0.1) and monocarboxylate transporters (MCT4, P < 0.1) was decreased. The function of “Concentration of lipid” was activated after 75% to 92% grain diet transition. Comparing to DG animals, the expression of ketogenesis (ACAT2, P < 0.05; HMGCS P < 0.1) and cholesterol synthesis related genes (HMGC and FDPs, P < 0.1) was deceased, while the expression of proton and cholesterol efflux related genes NHE3 and ABCA1 were increased (P < 0.05), and the function of “Storage of lipid” was inhibited in the ruminal epithelial of UG heifers. In addition, the function of differentially expressed (DE) genes in DG were involved in “T cell receptor signaling” and “complement and coagulation cascades” pathways, while the functions “metabolism of xenobiotics by cytochrome P450” and “p53 signaling pathway” were enriched for DE genes in UG animals. Furthermore, the single nucleotide polymorphisms (SNP) discovery by RNA-seq was performed, and SNP (g.46834311A > G) in FABP4 identified between two groups of animals (P < 0.1). The expression of genes involved in regulating lipid transport and fatty acid metabolism varied between DG and UG heifers during rapid 75% to 92% grain transition. The identified genes and SNP could be potential markers and may account for the varied ruminal pH responses between DG and UG heifers, which can be potentially applied in breeding and selecting beef cattle with more tolerance in dietary transition stress.

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