Polyphasic characterization of four species of Pseudanabaena (Oscillatoriales, Cyanobacteria) from China and insights into polyphyletic divergence within the Pseudanabaena genus

Abstract

Current cyanobacterial taxonomic studies are mainly performed through polyphasic characterization at the genus and/or species levels. In this study, eleven Pseudanabaena strains isolated in China were taxonomically and phylogenetically evaluated by investigating several characteristics, including morphological features, cellular ultrastructures, pigment composition, and 16S rRNa gene sequences. The strains were identified as four morphospecies, namely, Pseudanabaena mucicola, P. galeata, P. limnetica, and P. minima. The cellular ultrastructures of these species showed that peripheral thylakoids with 4-8 parallel layers were parietally distributed. Phylogenetic results based on 16S rRNa gene sequences indicated that most of the Pseudanabaena strains used in this study, including the eleven from China and three Pseudanabaena catenata strains from Genbank, gathered into one large cluster that represents the core of the genus Pseudanabaena. Several Pseudanabaena species/strains that represent different extreme environments were phylogenetically located outside the main stream cluster and should be removed under the genus Pseudanabaena on the basis of the role of the main stream species. Limnothrix strains were divided into two clades, and the taxonomic solution for these clades was discussed. This study is the first to report on the morphology and phylogeny of Pseudanabaena species in China, providing new insights into the taxonomy of the genera Pseudanabaena and Limnothrix.

Molecular specificity and detection for Pseudanabaena (cyanobacteria) species based on rbcLX sequences

“…A total of 105 uni-algal strains were isolated and identified at the Pseudanabaena (Yu et al, 2015) or Limnothrix (Zhu et al, 2012) genus (Supplementary Material 1: Table S1) level based on the morphological criteria described by Anagnostidis and Kom arek (Kom arek and Anagnostidis, 2005).…”

Effect of tributyltin chloride (TBT-Cl) exposure on expression ofHSP90β1in the river pufferfish (Takifugu obscurus): evidences for its immunologic function involving in exploring process

“…The program ClustalW2 was used to perform multiple sequence alignment (Chenna et al, 2003; Thompson et al, 2002). The phylogenic tree was constructed with MEGA 6.0 through a neighbor-joining (NJ) algorithm based on the deduced amino acid sequence of HSP90 for some other species (Kelly et al, 2006; Yu et al, 2015).…”

Dynamics and polyphasic characterization of odor-producing cyanobacterium Tychonema bourrellyi from Lake Erhai, China

“…The strains during the exponential growth phase were fixed following a procedure similar to that described by Shao et al (2011). Briefly, the strains in the exponential growth phase were fixed at room temperature for 2 h in 2.5 % glutaraldehyde buffered with phosphate buffer (pH 7.0), then postfixed in 1 % osmium tetraoxide, dehydrated, and embedded in Spurr's resin (Yu et al 2015). The fixed samples were observed under a TEM (Philips TECNAI G2) at an accelerating voltage of 80 kV.…”

“…The absorption spectra of the strains were measured by dual beam spectrophotometer using the filter membrane methods (Yu et al 2015). The procedure is described as follows.…”