title: Sporadic distribution and distinctive variations of cylindrospermopsin genes in cyanobacterial strains and environmental samples from Chinese freshwater bodies.
abstract: Increasing reports of cylindrospermopsins (CYNs) in freshwater ecosystems have promoted the demand for identifying all of the potential CYN-producing cyanobacterial species. The present study explored the phylogenetic distribution and evolution of cyr genes in cyanobacterial strains and water samples from China. Four Cylindrospermopsis strains and two Raphidiopsis strains were confirmed to produce CYNs. Mutant cyrI and cyrK genes were observed in these strains. Cloned cyr gene sequences from eight water bodies were clustered with cyr genes from Cylindrospermopsis and Raphidiopsis (C/R group) in the phylogenetic trees with high similarities (99%). Four cyrI sequence types and three cyrJ sequence types were observed to have different sequence insertions and repeats. Phylogenetic analysis of the rpoC1 sequences of the C/R group revealed four conserved clades, namely, clade I, clade II, clade III, and clade V. High sequence similarities (>97%) in each clade and a divergent clade IV were observed. Therefore, CYN producers were sporadically distributed in congeneric and paraphyletic C/R group species in Chinese freshwater ecosystems. In the evolution of cyr genes, intragenomic translocations and intergenomic transfer between local Cylindrospermopsis and Raphidiopsis were emphasized and probably mediated by transposases. This research confirms the existence of CYN-producing Cylindrospermopsis in China and reveals the distinctive variations of cyr genes.
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China University of Chinese Academy of Sciences, Beijing, People's Republic of China.
authors.forename: Yongguang
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China University of Chinese Academy of Sciences, Beijing, People's Republic of China.
authors.forename: Peng
authors.initials: P
authors.lastname: Xiao
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China.
authors.forename: Gongliang
authors.initials: G
authors.lastname: Yu
authors.affiliation: Resources and Environment College, Hunan Agricultural University, Changsha, People's Republic of China.
authors.forename: Jihai
authors.initials: J
authors.lastname: Shao
authors.affiliation: Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization, Hunan Agricultural University, Changsha, People's Republic of China.
authors.forename: Deming
authors.initials: D
authors.lastname: Liu
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Cidade Universitária, Rio de Janeiro, Brazil.
authors.forename: Sandra M F O
authors.initials: SM
authors.lastname: Azevedo
authors.affiliation: Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, People's Republic of China reli@ihb.ac.cn.
authors.forename: Renhui
authors.initials: R
authors.lastname: Li
mesh_terms: D000470:Alkaloids; D001427:Bacterial Toxins; D002681:China; D016000:Cluster Analysis; D000458:Cyanobacteria / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D000087522:Cyanobacteria Toxins; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005618:Fresh Water / Q000382:microbiology*; D005838:Genotype; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014498:Uracil / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000470:Alkaloids; D001427:Bacterial Toxins; D000087522:Cyanobacteria Toxins; D004269:DNA, Bacterial; C089595:cylindrospermopsin; D014498:Uracil