title: Determination of dosage compensation and comparison of gene expression in a triploid hybrid fish.
abstract: Polyploidy and hybridization are both recognized as major forces in evolution. Most of our current knowledge about differences in gene regulation in polyploid hybrids comes from plant studies. The gene expression of diverged genomes and regulatory interactions are still unclear in lower vertebrates.
  
  
  
  We generated 229 million cleaned reads (42.23 Gbp) from triploid of maternal grass carp (Ctenopharyngodon idellus, Cyprininae, 2n = 48) × paternal blunt snout bream (Megalobrama amblycephala, Cultrinae, 2n = 48) and their diploid parents using next-generation sequencing. In total, 157,878 contigs were assembled and 15,444 genes were annotated. We examined gene expression level changes among the parents and their triploid offspring. The mechanisms of dosage compensation that reduced triploid expression levels to the diploid state were determined in triploid fish. In this situation, novel gene expression and gene silencing were observed. Then, we established a model to determine the extent and direction of expression level dominance (ELD) and homoeolog expression bias (HEB) based on the relative expression level among the parents and their triploid offspring.
  
  
  
  Our results showed that the genome-wide ELD was biased toward maternal genome in triploid. Extensive alterations in homoeolog expression suggested a combination of regulatory and epigenetic interactions through the transcriptome network. Additionally, the expression patterns of growth genes provided insights into the relationship between the characteristics of growth and underlying mechanisms in triploids. Regulation patterns of triploid state suggest that various expression levels from the initial genomic merger have important roles in adaptation.
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ren
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Chenchen
authors.initials: C
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Wuhui
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Jialin
authors.initials: J
authors.lastname: Cui
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Xingjun
authors.initials: X
authors.lastname: Tan
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Yafeng
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Min
authors.initials: M
authors.lastname: Tao
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Developmental Biology of Freshwater Fish, Hunan Normal University, Changsha, 410081, China. lsj@hunnu.edu.cn.
authors.forename: Shaojun
authors.initials: S
authors.lastname: Liu
mesh_terms: D000818:Animals; D004171:Diploidy; D004303:Dosage Compensation, Genetic; D005260:Female; D005399:Fishes / Q000235:genetics*; D018628:Gene Dosage; D015870:Gene Expression; D020869:Gene Expression Profiling; D005799:Genes, Dominant; D006824:Hybridization, Genetic; D008297:Male; D019655:Quantitative Trait, Heritable; D015203:Reproducibility of Results; D059467:Transcriptome; D057885:Triploidy
keywords: Biased expression; Dosage compensation; Genomic dominance; Transcriptome; Triploid