title: The transcriptomes of the crucian carp complex (Carassius auratus) provide insights into the distinction between unisexual triploids and sexual diploids.
abstract: Both sexual reproduction and unisexual reproduction are adaptive strategies for species survival and evolution. Unisexual animals have originated largely by hybridization, which tends to elevate their heterozygosity. However, the extent of genetic diversity resulting from hybridization and the genomic differences that determine the type of reproduction are poorly understood. In Carassius auratus, sexual diploids and unisexual triploids coexist. These two forms are similar morphologically but differ markedly in their modes of reproduction. Investigation of their genomic differences will be useful to study genome diversity and the development of reproductive mode. We generated transcriptomes for the unisexual and sexual populations. Genes were identified using homology searches and an ab initio method. Estimation of the synonymous substitution rate in the orthologous pairs indicated that the hybridization of gibel carp occurred 2.2 million years ago. Microsatellite genotyping in each individual from the gibel carp population indicated that most gibel carp genes were not tri-allelic. Molecular function and pathway comparisons suggested few gene expansions between them, except for the progesterone-mediated oocyte maturation pathway, which is enriched in gibel carp. Differential expression analysis identified highly expressed genes in gibel carp. The transcriptomes provide information on genetic diversity and genomic differences, which should assist future studies in functional genomics.
authors.affiliation: Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150001, China. xiaoyz0511@163.com.
authors.forename: Chun-Yan
authors.initials: CY
authors.lastname: Li
authors.affiliation: The Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China. lijt83@gmail.com.
authors.forename: Jiong-Tang
authors.initials: JT
authors.lastname: Li
authors.affiliation: Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150001, China. youyikuang@hotmail.com.
authors.forename: You-Yi
authors.initials: YY
authors.lastname: Kuang
authors.affiliation: The Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China. sdxuru@163.com.
authors.forename: Ru
authors.initials: R
authors.lastname: Xu
authors.affiliation: The Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China. zhaozx@cafs.ac.cn.
authors.forename: Zi-Xia
authors.initials: ZX
authors.lastname: Zhao
authors.affiliation: The Centre for Applied Aquatic Genomics, Chinese Academy of Fishery Sciences, Beijing 100141, China. hougy@cafs.ac.cn.
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Hou
authors.affiliation: Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China. lianghw@yfi.ac.cn.
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Liang
authors.affiliation: Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150001, China. sunxw2002@163.com.
authors.forename: Xiao-Wen
authors.initials: XW
authors.lastname: Sun
mesh_terms: D000818:Animals; D002347:Carps / Q000235:genetics* / Q000502:physiology; D004171:Diploidy; D005260:Female; D014644:Genetic Variation; D019656:Loss of Heterozygosity; D008297:Male; D011110:Polymorphism, Genetic; D012098:Reproduction; D059467:Transcriptome; D057885:Triploidy