title: Transcriptome analysis revealed positive selection of immune-related genes in tilapia.
abstract: High-throughput sequencing of transcriptome promises a new approach for detecting evolutionary divergence among species. Up to now, the information about evolution of immune genes in cultured fish, especially in tilapias which would aid to understand the molecular basis of immune phenotypic differentiation is still lack. Thus, in the present study, we used high-throughput sequencing to obtain large amount of gene sequences in blue tilapia and characterized the diversity of orthologs among Nile tilapia, blue tilapia and zebrafish. A total of 52,424,506 raw reads, representing 31,404 unigenes were obtained from blue tilapia cDNA library of mixed tissues, including brain, pituitary, gill, heart, liver, spleen, kidney, intestine, muscle, testis and ovary. Based on Ks value, we calculated that the divergence time between Nile tilapia and blue tilapia is 2.93 million years ago. And the tilapias are both apart from zebrafish in 197 million years ago. Furthermore, the positive selected genes were identified by calculating of Ka/Ks ratio. Several immune-related genes were identified as positively selected genes, such as Notch2 and nfatc3b. Considering that these genes play crucial role in immune regulating function, the immune system genes met a great variation under environment selection in tilapias which suggests fast evolution in immune system of cultured tilapias.
authors: Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Sciences, Nanning, Guangxi 530021, China.
authors: Jun
authors: J
authors: Xiao
authors: Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Sciences, Nanning, Guangxi 530021, China.
authors: Huan
authors: H
authors: Zhong
authors: Department of Biotechnology and Environmental Science, Changsha University, Changsha 410003, China.
authors: Zhen
authors: Z
authors: Liu
authors: Key Laboratory for Genetic Breeding of Aquatic Animals, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, Jiangsu 214081, China.
authors: Fan
authors: F
authors: Yu
authors: Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Sciences, Nanning, Guangxi 530021, China.
authors: Yongju
authors: Y
authors: Luo
authors: Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Sciences, Nanning, Guangxi 530021, China.
authors: Xi
authors: X
authors: Gan
authors: Guangxi Key Laboratory of Aquatic Genetic Breeding and Healthy Aquaculture, Guangxi Academy of Fishery Sciences, Nanning, Guangxi 530021, China; Department of Biotechnology and Environmental Science, Changsha University, Changsha 410003, China. Electronic address: zhouyi1982cn@126.com.
authors: Yi
authors: Y
authors: Zhou
mesh_terms: D000818:Animals; D023681:Cichlids / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D012641:Selection, Genetic; D059467:Transcriptome
chemical_list: D029941:Fish Proteins
keywords: Blue tilapia; Divergence time; High-throughput sequencing; Immune genes; Positive selection