Key Laboratory of Bio-resources and Eco-environment (Ministry of Education), College of Life Sciences, Sichuan University, Chengdu, P.R. China.
Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, P.R. China.
DNA Cell Biol. 2020 Oct;39(10):1872-1885. doi: 10.1089/dna.2020.5537. Epub 2020 Sep 16.
Hyenas (family Hyaenidae) occupy a variety of different niches, of which the striped hyena () scavenges mainly on the carcasses of animals. We compared its genome with the genomes of nine other mammals, focusing on similarities and differences in chemoreception, detoxification, digestive, and immune systems. The results showed that the striped hyena's immune and digestive system-related gene families have significantly expanded, which was likely to be an adaptive response to its scavenging lifestyle. In addition, 88 and 26 positive selected genes (PSGs) were identified in the immune system and digestive system, respectively, which may be the molecular basis for immune defense system to effectively resist pathogen invasion. Functional enrichment analysis of PSGs revealed that most of them were involved in the immune regulation process. Among them, eight specific missense mutations were found in two PSGs ( class II antigen and class II antigen ), suggesting important reorganization of the immune system in the striped hyena. Moreover, we identified one cathelicidin gene and four defensin genes in the striped hyenas by genome mining, which have high-efficiency and broad-spectrum antimicrobial activity. Of particular interest, a striped hyena-specific missense mutation was found in the cathelicidin gene. PolyPhen-2 classified the missense mutation as a harmful mutation, which may have aided in immune adaptation to carrion feeding. Our genomic analyses on the striped hyena provided insights into its success in the adaptation to the scavenging lifestyle.
鬣狗（鬣狗科）占据了多种不同的生态位，其中条纹鬣狗主要以动物尸体为食。我们将其基因组与其他 9 种哺乳动物的基因组进行了比较，重点研究了嗅觉、解毒、消化和免疫系统的相似性和差异。结果表明，条纹鬣狗的免疫和消化系统相关基因家族显著扩张，这可能是对其食腐生活方式的一种适应性反应。此外，在免疫系统和消化系统中分别鉴定出 88 个和 26 个正选择基因（PSG），这可能是免疫防御系统有效抵抗病原体入侵的分子基础。PSG 的功能富集分析表明，它们大多数参与了免疫调节过程。其中，在两个 PSG（类 II 抗原和类 II 抗原）中发现了 8 个特定的错义突变，表明条纹鬣狗的免疫系统发生了重要的重组。此外，我们通过基因组挖掘在条纹鬣狗中鉴定到一个 cathelicidin 基因和四个 defensin 基因，它们具有高效广谱的抗菌活性。特别有趣的是，在 cathelicidin 基因中发现了一个条纹鬣狗特异性的错义突变。Polyphen-2 将该错义突变归类为有害突变，这可能有助于免疫适应食腐生活。我们对条纹鬣狗的基因组分析为其成功适应食腐生活方式提供了新的见解。
