Aplicações de técnicas moleculares de nova geração (NGS) para o estudo do desempenho reprodutivo de touros e vacas leiteiras

Abstract

Study 1 aimed to produce a methylation profile in genome in both populations, and to identify differential epigenetic signatures between high motility (HM) and low motility (LM) sperm. Study 2 aimed to characterize the metabolic pathways associated to early lactation in Holstein cows using RNA-seq data obtained from subcutaneous fat tissue samples collected at three time points: at 2 (T0), 30 (T1) and 90 (T3) days postpartum. In study 1, we explored the methylation of cytosine-guanine dinucleotides (CpGs) in HM and LM sperm populations in Bos taurus separated by Percoll. Methylation patterns of high and low motility sperm were investigated by bisulphite sequencing. The comparison between the populations of HM and LM sperm revealed that the variation of methylation affects the genes involved in the organization of chromatin and that methylation occurred in genes associated with the remodeling of the DNA structure, as well as in a repetitive element BTSAT4 in pericentromeric regions. Thus, it is suggested that the maintenance of chromosome structure through epigenetic regulation is crucial for the correct functionality of sperm. For study 2, total RNA was extracted from subcutaneous adipose tissue on the day of birth (D0), 30 days postpartum (D30) and ninety days postpartum (D90) and comparisons were made between the groups mentioned. A total of 12.294 genomes were identified and subjected to a filtering, identifying a total of 405.435.505 genes, in which differentially expressed genes were analyzed using the False Discovery Rate (FDR = 0.05). Metabolic pathways associated to the early lactation in Holstein cows were characterized using RNA-seq data obtained from subcutaneous fat tissue samples collected at three time points: at 2 (T0), 30 (T1) and 90 (T3) days postpartum. The enrichment analysis identified 142 metabolic pathways. The most significative were insulin secretion, oxytocin signaling, glycolysis/gluconeogenesis, pyruvate metabolism, insulin resistance, calcium signalling, GnRH (Gonadotropin releasing hormone), MAPK (mitogen-activated protein kinase), adipocytokine signaling, and the renin−angiotensin system. All these pathways are important metabolic routes in lactating dairy cattle.