Fallahsharoudi Amir, de Kock Neil, Johnsson Martin, Bektic Lejla, Ubhayasekera S J Kumari A, Bergquist Jonas, Wright Dominic, Jensen Per
AVIAN Behavioural Genomics and Physiology Group, Department of Physics, Chemistry and Biology, Linköping University, 58183, Sweden.
Department of Chemistry, BMC, Analytical Chemistry and Neurochemistry, University of Uppsala, 75124, Sweden.
G3 (Bethesda). 2017 Feb 9;7(2):497-504. doi: 10.1534/g3.116.037721.
The stress response has been largely modified in all domesticated animals, offering a strong tool for genetic mapping. In chickens, ancestral Red Junglefowl react stronger both in terms of physiology and behavior to a brief restraint stress than domesticated White Leghorn, demonstrating modified functions of the hypothalamic-pituitary-adrenal (HPA) axis. We mapped quantitative trait loci (QTL) underlying variations in stress-induced hormone levels using 232 birds from the 12th generation of an advanced intercross between White Leghorn and Red Junglefowl, genotyped for 739 genetic markers. Plasma levels of corticosterone, dehydroepiandrosterone (DHEA), and pregnenolone (PREG) were measured using LC-MS/MS in all genotyped birds. Transcription levels of the candidate genes were measured in the adrenal glands or hypothalamus of 88 out of the 232 birds used for hormone assessment. Genes were targeted for expression analysis when they were located in a hormone QTL region and were differentially expressed in the pure breed birds. One genome-wide significant QTL on chromosome 5 and two suggestive QTL together explained 20% of the variance in corticosterone response. Two significant QTL for aldosterone on chromosome 2 and 5 (explaining 19% of the variance), and one QTL for DHEA on chromosome 4 (explaining 5% of the variance), were detected. Orthologous DNA regions to the significant corticosterone QTL have been previously associated with the physiological stress response in other species but, to our knowledge, the underlying gene(s) have not been identified. had an expression QTL (eQTL) colocalized with the corticosterone QTL on chromosome 5 and had an eQTL colocalized with the aldosterone QTL on chromosome 2. Furthermore, in both cases, the expression levels of the genes were correlated with the plasma levels of the hormones. Hence, both these genes are strong putative candidates for the domestication-induced modifications of the stress response in chickens. Improved understanding of the genes associated with HPA-axis reactivity can provide insights into the pathways and mechanisms causing stress-related pathologies.
在所有家养动物中，应激反应都有很大改变，这为基因定位提供了有力工具。在鸡中，野生原鸡对短暂束缚应激在生理和行为方面的反应比家养白来航鸡更强，这表明下丘脑 - 垂体 - 肾上腺（HPA）轴的功能发生了改变。我们使用白来航鸡和原鸡高级杂交第12代的232只鸡，对739个遗传标记进行基因分型，来定位应激诱导激素水平变化的数量性状基因座（QTL）。使用液相色谱 - 串联质谱法（LC - MS/MS）测量所有基因分型鸡的皮质酮、脱氢表雄酮（DHEA）和孕烯醇酮（PREG）的血浆水平。在用于激素评估的232只鸡中的88只鸡的肾上腺或下丘脑测量候选基因的转录水平。当基因位于激素QTL区域且在纯种鸡中差异表达时，对其进行表达分析。5号染色体上一个全基因组显著QTL和两个提示性QTL共同解释了皮质酮反应中20%的变异。在2号和5号染色体上检测到两个醛固酮的显著QTL（解释19%的变异），以及4号染色体上一个DHEA的QTL（解释5%的变异）。与显著皮质酮QTL的直系同源DNA区域先前已与其他物种的生理应激反应相关，但据我们所知，其潜在基因尚未确定。 在5号染色体上有一个表达数量性状基因座（eQTL）与皮质酮QTL共定位， 在2号染色体上有一个eQTL与醛固酮QTL共定位。此外，在这两种情况下，基因的表达水平都与激素的血浆水平相关。因此，这两个基因都是鸡应激反应驯化诱导修饰的有力候选基因。更好地理解与HPA轴反应性相关的基因可以深入了解导致应激相关病理的途径和机制。
