Effects of a transient increase or decrease in temperature during in ovo development on epigenetic, transcriptomic and metabolic features of day-old broilers and laying chicks

点击翻译按钮获取中文摘要

There is evidence from our own and numerous other published studies that modulation of incubation temperature has direct effects on in ovo and sustained effects on ex ovo development in poultry. Studies related to the concepts of prenatal programming and the “thrifty phenotype hypothesis” have mainly focused on the negative effects that prenatal events may exert later in life (Hales & Barker 1992). However, prenatal "aberrations" may also have a positive influence on adaptation to postnatal conditions. The targeted modulation of conditions during in ovo development could be a means for improving productive adaptability in terms of health and well-being, growth and thermotolerance. However taking advantage of these programming phenomena requires a comprehensive knowledge of the underlying molecular mechanisms. The in ovo development of birds is a valuable model for studying molecular routes mediating environmental influences on early development and their long-term consequences. In this study, we aim to investigate the effects of increased and decreased incubation temperatures (37.8°C +/- 1°C) within a specific treatment period (embryonic day (ED) 10-13; phase of development of secondary myofibres and satellite cells) on metabolic, biochemical and histological traits, as well as on gene expression and epigenetic changes in male and female day-old chicks of broilers and layers. In addition to the factors of production type and sex, the study design also takes into account the influence of muscle type by examining the M. pectoralis, which consists only of glycolytic muscle fibres, and the M. gastrocnemius, which also consists of oxidative muscle fibres, thus forming different niches of satellite cell development. Analyses of carbohydrate- and fat-related energy metabolism will be complemented by holistic metabolome and mRNA expression profiling. Comparative ATACseq analyses will be performed to identify treatment-, lineage- and sex-associated epigenetic modifications. In addition, ATACseq will be used in single cells to generate prototype genome-wide chromatin accessibility maps in the heterogeneous tissues of the M gastrocnemius of broiler and layer hens. The aim is to uncover functional relationships along the genotype-phenotype map from the genome to the metabolome via the epigenome and transcriptome in response to changes in incubation temperature. Experimental modulation of temperature during in ovo development in combination with observation of its effects on metabolic phenotypes, gene expression and epigenetic changes will allow the identification of genes and pathways involved in fetal programming processes related to metabolism, health and well-being and productive adaptability.