Toxicity phenotype does not correlate with phylogeny of Cylindrospermopsis raciborskii strains |
| |
Authors: | Karina Stucken Alejandro A Murillo Katia Soto-Liebe Juan J Fuentes-Valdés Marco A Méndez Mónica Vásquez |
| |
Institution: | 1. Laboratorio de Ecología Microbiana y Toxicología Ambiental, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331010 Santiago, Chile;2. Millennium Nucleus on Microbial Ecology and Environmental Microbiology and Biotechnology, Alameda 340, 6513492 Santiago, Chile;3. Laboratorio de Genómica Evolutiva, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile |
| |
Abstract: | Cylindrospermopsis raciborskii is a species of freshwater, bloom-forming cyanobacterium. C. raciborskii produces toxins, including cylindrospermopsin (hepatotoxin) and saxitoxin (neurotoxin), although non toxin-producing strains are also observed. In spite of differences in toxicity, C. raciborskii strains comprise a monophyletic group, based upon 16S rRNA gene sequence identities (greater than 99%). We performed phylogenetic analyses; 16S rRNA gene and 16S-23S rRNA gene internally transcribed spacer (ITS-1) sequence comparisons, and genomic DNA restriction fragment length polymorphism (RFLP), resolved by pulsed-field gel electrophoresis (PFGE), of strains of C. raciborskii, obtained mainly from the Australian phylogeographic cluster. Our results showed no correlation between toxic phenotype and phylogenetic association in the Australian strains. Analyses of the 16S rRNA gene and the respective ITS-1 sequences (long L, and short S) showed an independent evolution of each ribosomal operon. The genes putatively involved in the cylindrospermopsin biosynthetic pathway were present in one locus and only in the hepatotoxic strains, demonstrating a common genomic organization for these genes and the absence of mutated or inactivated biosynthetic genes in the non toxic strains. In summary, our results support the hypothesis that the genes involved in toxicity may have been transferred as an island by processes of gene lateral transfer, rather than convergent evolution. |
| |
Keywords: | Phylogeny Cylindrospermopsis raciborskii PFGE ITS lateral gene transfer 16S Rdna |
本文献已被 ScienceDirect 等数据库收录! |
|