title: The Rho GTPase Family Genes in Bivalvia Genomes: Sequence, Evolution and Expression Analysis.
abstract: BACKGROUND
  Rho GTPases are important members of the Ras superfamily, which represents the largest signaling protein family in eukaryotes, and function as key molecular switches in converting and amplifying external signals into cellular responses. Although numerous analyses of Rho family genes have been reported, including their functions and evolution, a systematic analysis of this family has not been performed in Mollusca or in Bivalvia, one of the most important classes of Mollusca.
  
  
  RESULTS
  In this study, we systematically identified and characterized a total set (Rho, Rac, Mig, Cdc42, Tc10, Rnd, RhoU, RhoBTB and Miro) of thirty Rho GTPase genes in three bivalve species, including nine in the Yesso scallop Patinopecten yessoensis, nine in the Zhikong scallop Chlamys farreri, and twelve in the Pacific oyster Crassostrea gigas. Phylogenetic analysis and interspecies comparison indicated that bivalves might possess the most complete types of Rho genes in invertebrates. A multiple RNA-seq dataset was used to investigate the expression profiles of bivalve Rho genes, revealing that the examined scallops share more similar Rho expression patterns than the oyster, whereas more Rho mRNAs are expressed in C. farreri and C. gigas than in P. yessoensis. Additionally, Rho, Rac and Cdc42 were found to be duplicated in the oyster but not in the scallops. Among the expanded Rho genes of C. gigas, duplication pairs with high synonymous substitution rates (Ks) displayed greater differences in expression.
  
  
  CONCLUSIONS
  A comprehensive analysis of bivalve Rho GTPase family genes was performed in scallop and oyster species, and Rho genes in bivalves exhibit greater conservation than those in any other invertebrate. This is the first study focusing on a genome-wide characterization of Rho GTPase genes in bivalves, and the findings will provide a valuable resource for a better understanding of Rho evolution and Rho GTPase function in Bivalvia.
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Li
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Ruijia
authors.initials: R
authors.lastname: Wang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Xiaogang
authors.initials: X
authors.lastname: Xun
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Wenqian
authors.initials: W
authors.lastname: Jiao
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Mengran
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Shuyue
authors.initials: S
authors.lastname: Wang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Wang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Huang
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Hu
authors.affiliation: Ministry of Education Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
authors.forename: Zhenmin
authors.initials: Z
authors.lastname: Bao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000235:genetics*; D019143:Evolution, Molecular; D015870:Gene Expression; D016678:Genome; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics*
chemical_list: D020741:rho GTP-Binding Proteins