The Comparative Analysis of Phenotypic and Whole Transcriptome Gene Expression Data of Ascites Susceptible Versus Ascites Resistant Chickens. The Comparative Analysis of Phenotypic and Whole Transcriptome Gene Expression Data of Ascites Susceptible Versus Ascites Resistant Chickens

Ascites syndrome (AS) is a metabolic disorder that mainly occurs at later ages of meat-type chickens. Despite many research, there is no consensus about the origin of this syndrome. Our main purpose were to investigate the syndrome using both phenotypic and RNA-Seq data to elucidate the most causative factors predisposing the birds to AS. Phenotypic data analysis showed that AS indicator traits (AITs) were moderate to high heritable. Inexistence of consistent direct genetic correlation between AITs and growth related traits (GRTs), indicated that neither faster growth rate nor heavier body weight is the most causative factor affecting the susceptibility of broilers to AS. However, respiratory capacity was revealed to be the most probable factor predisposing the birds to AS, as both lung weight and lung percentage were negatively correlated with AITs. Transcriptomic data analysis revealed 125 differentially expressed genes (DEGs) between the ascitic and healthy groups. Up-regulated genes in ascitic group enriched mainly in gas transport biological process, while down-regulated genes involved in defense response to bacteria, biological adhesion, cell adhesion, killing of cells of another organism and cell division. Genetic association of the DEGs with human cardiovascular diseases suggested an excessive heart problems of the ascitic chicks. Heart is, probably, the first tissue suffering from the incompetence of small respiratory system of the AS-susceptible chickens. In other word, tissue hypoxia, that cause free radicals to concentrate in heart cells, may be the commencement of events that finally result to heart failure, suffocation and death of chicks due to the AS. Overall design: Right heart ventricule mRNA profiles of 39-day old ascitic and healthy chickens were generated by deep sequencing, in duplicate using Illumina Hiseq 2000

腹水综合征（Ascites syndrome, AS）是一种主要发生于肉用鸡养殖后期的代谢紊乱性疾病。尽管已有诸多相关研究，但目前对于该综合征的致病起源尚未形成统一定论。本研究的核心目的旨在通过表型数据与RNA测序（RNA-Seq）数据，解析肉鸡易感腹水综合征的关键致病因素。表型数据分析结果显示，腹水综合征指示性状（Ascites indicator traits, AITs）具有中等至高等的遗传力。未发现AITs与生长相关性状（growth related traits, GRTs）之间存在稳定的直接遗传相关，这表明生长速率过快与体重过高均非影响肉鸡易感腹水综合征的核心致病因素。但研究发现呼吸功能才是肉鸡易感腹水综合征的最关键易感因素：肺脏重量与肺脏体重占比均与AITs呈负相关。转录组数据分析显示，腹水组与健康组肉鸡共鉴定得到125个差异表达基因（differentially expressed genes, DEGs）。腹水组上调基因主要富集于气体运输生物学过程，而下调基因则参与细菌防御反应、生物黏附、细胞黏附、异源细胞杀伤以及细胞分裂等生物学过程。差异表达基因与人类心血管疾病的遗传关联分析提示，腹水组肉鸡存在显著的心脏功能异常。心脏或许是腹水综合征易感肉鸡呼吸系统功能不全时首个受累的组织。换言之，组织缺氧会导致自由基在心肌细胞内蓄积，这一过程可能是最终引发肉鸡因腹水综合征出现心力衰竭、窒息乃至死亡的起始事件。研究整体设计：采用Illumina HiSeq 2000平台，对39日龄腹水组与健康组肉鸡的右心室心肌组织进行双重复深度测序，以获取其mRNA表达谱。