Taxonomic and phylogenetic evaluation of Limnothrix strains (Oscillatoriales, Cyanobacteria) by adding Limnothrix planktonica strains isolated from central China

Six Limnothrix strains, isolated for the first time from a shallow eutrophic lake in central China, were taxonomically and phylogenetically evaluated by investigating their polyphasic characteristics, including morphological features, cellular ultrastructures, and 16S rRNA gene sequences. All the six strains were morphologically similar, and their trichomes were in average 1.7 mu m wide and cells 4.0 mu m long, and having small gas vesicles within cells, and therefore identified as Limnothrix planctonica (Woloszynska) Meffert. Cellular ultrastructures of them showed that peripheral thylakoids with 3-5 parallel layers were parietally distributed in the cells. The phylogenetic results based on the 16S rRNA gene sequences showed that all the Limnothrix strains, including the six in this study and those from the Genbank, formed two distinct clusters. The similarity in 16S rDNA sequences between these two clusters was lower than 90%, indicating that these Limnothrix strains belong to different genera. This is the first report on the morphology and phylogeny of L. planctonica strains, providing the new information on taxonomy of the genus Limnothrix.Six Limnothrix strains, isolated for the first time from a shallow eutrophic lake in central China, were taxonomically and phylogenetically evaluated by investigating their polyphasic characteristics, including morphological features, cellular ultrastructures, and 16S rRNA gene sequences. All the six strains were morphologically similar, and their trichomes were in average 1.7 mu m wide and cells 4.0 mu m long, and having small gas vesicles within cells, and therefore identified as Limnothrix planctonica (Woloszynska) Meffert. Cellular ultrastructures of them showed that peripheral thylakoids with 3-5 parallel layers were parietally distributed in the cells. The phylogenetic results based on the 16S rRNA gene sequences showed that all the Limnothrix strains, including the six in this study and those from the Genbank, formed two distinct clusters. The similarity in 16S rDNA sequences between these two clusters was lower than 90%, indicating that these Limnothrix strains belong to different genera. This is the first report on the morphology and phylogeny of L. planctonica strains, providing the new information on taxonomy of the genus Limnothrix

Remote Estimation of Chlorophyll-a in Inland Waters by a NIR-Red-Based Algorithm: Validation in Asian Lakes

Satellite remote sensing is a highly useful tool for monitoring chlorophyll-a concentration (Chl-a) in water bodies. Remote sensing algorithms based on near-infrared-red (NIR-red) wavelengths have demonstrated great potential for retrieving Chl-a in inland waters. This study tested the performance of a recently developed NIR-red based algorithm, SAMO-LUT (Semi-Analytical Model Optimizing and Look-Up Tables), using an extensive dataset collected from five Asian lakes. Results demonstrated that Chl-a retrieved by the SAMO-LUT algorithm was strongly correlated with measured Chl-a (R2 = 0.94), and the root-mean-square error (RMSE) and normalized root-mean-square error (NRMS) were 8.9 mg∙m−3 and 72.6%, respectively. However, the SAMO-LUT algorithm yielded large errors for sites where Chl-a was less than 10 mg∙m−3 (RMSE = 1.8 mg∙m−3 and NRMS = 217.9%). This was because differences in water-leaving radiances at the NIR-red wavelengths (i.e., 665 nm, 705 nm and 754 nm) used in the SAMO-LUT were too small due to low concentrations of water constituents. Using a blue-green algorithm (OC4E) instead of the SAMO-LUT for the waters with low constituent concentrations would have reduced the RMSE and NRMS to 1.0 mg∙m−3 and 16.0%, respectively. This indicates (1) the NIR-red algorithm does not work well when water constituent concentrations are relatively low; (2) different algorithms should be used in light of water constituent concentration; and thus (3) it is necessary to develop a classification method for selecting the appropriate algorithm

Genotypes of ITS region of rRNA in Microcystis (Cyanobacteria) populations in Erhai Lake (China) and their correlation with eutrophication level

Previous studies on spatiotemporal changes of Microcystis genotypes have shown that the existence and succession of dominant genotypes always occur in eutrophicated freshwater bodies. However, few studies have focused on the correlation between genotype composition and eutrophication level. In the present study, clone libraries of the internal transcribed spacer (ITS) of rrn operon were sequenced from Microcystis populations in Erhai Lake, a subtropical plateau lake in the preliminary eutrophication stage. The genotype composition of the Microcystis populations was highly variable at spatiotemporal scales, and 473 ITS genotypes were identified from the 800 ITS sequences obtained. However, no significantly dominant ITS genotypes existed in the lake. Comparison of Erhai Lake with four major lakes in China, namely, Taihu, Chaohu, Gucheng, and Shijiu Lakes, showed that the Microcystis ITS genotypes and genetic diversity were negatively correlated with eutrophication level. Extensive comparison of the Microcystis ITS genotypes from waters worldwide revealed that 440 ITS genotypes were unique to Erhai Lake, and no obvious phylogenetic correlations can be detected among the dominant genotypes from different water bodies. The high genetic diversity of the Microcystis populations in Erhai Lake may have resulted from the effect of the early stage of eutrophication

<i>Nodosilinea hunanesis</i> sp. nov. (Prochlorotrichaceae, Synechococcales) from a Freshwater Pond in China Based on a Polyphasic Approach

A cyanobacterial strain (ZJJ01), morphologically identified as a Leptolyngbya-like species was isolated from a freshwater pond in Zhangjiajie National Forest Park, China, and it was characterized through a polyphasic study based on morphological, ecological, and molecular data. Morphologically, the strain fits the description of Leptolyngbya well, but under further examination, it formed a distinctive structure, namely nodules, which confirmed that it belonged to the genus of Nodosilinea. The 16S rRNA gene threshold value and 16S rRNA phylogenetic analyses clearly confirmed that the studied strain belongs to the genus Nodosilinea but that it is phylogenetically distinct from the 10 other species of Nodosilinea. Furthermore, The D1–D1’ and Box–B helix of the 16S–23S ITS region of the strain ZJJ01 were also different from those of previously described Nodosilinea species. On the basis of this polyphasic approach, here, we provide a description of the new taxon: Nodosilinea hunanesis sp. nov

The morphological and molecular detection for the presence of toxic Cylindrospermopsis (Nostocales, Cyanobacteria) in Beijing city, China

Cylindrospermopsis raciborskii and its highly similar relatives Raphidiopsis species have been recognized as globally invasive and expansive filamentous cyanobacteria causing water blooms. Reports on C. raciborskii/Raphidiopsis species and their harmful metabolites such as hepatotoxic cylindrospermopsins (CYNs) in Chinese waters have been increasing, but mostly restricted to the southern regions of China. To further explore the existence and distribution of C. raciborskii in China, six water samples from Beijing city were morphologically and molecularly examined. Five samples of the six were shown to have Cylindrospermopsis filaments with straight and spiral morphotypes. PCR detection targeting on Cylindrospermopsis/Raphidiopsis specific 16S rRNA gene region also showed the positive amplification, and such amplifications were confirmed by sequencing and phylogenetic analysis. As well, three of the five Cylindrospermopsis containing samples were shown to have cyrJ-a gene of CYN synthesis gene cluster. The results represented the presence of toxic Cylindrospermopsis at the most northern line in China so far, indicating rapid expansion of this harmful invasive cyanobacterium. It is strongly suggested that the monitoring on C. raciborskii/Raphidiopsis species and their production of cylindrospermopsin should be emphasized in Beijing and even more northern parts of China

The Golod-Shafarevich inequality for pro-p groups and abstract groups

Orientador: Dessislava Hristova KochloukovaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação CientíficaResumo: Neste trabalho estuda-se os principais resultados dados por J. Wilson no artigo "Finite Presentations of Pro-p Groups and Discrete Groups", relacionados à Desigualdade de Golod-¿afarevi? para uma ampla classe de grupos pro-p e abstratos infinitos. Apresentamos a teoria básica de grupos livres abstratos, levando à noção de apresentação de grupos, com foco em apresentações finitas. É feito um estudo sobre grupos profinitos, particularmente no caso pro-p. Abrange-se definições, propriedades algébricas e topológicas básicas, bem como o caso de finitos geradores com o subgrupo de Frattini, e conceitos de completamentos, de grupos pro-p livres, de apresentações de grupos pro-p e de álgebras de grupo completas. No capítulo final estudamos os resultados principais para grupos pro-p e abstratos finitamente apresentáveis, que incluem grupos solúveis e implicações na estrutura de certos grupos satisfazendo a Desigualdade. Os anexos relacionam a teoria aqui apresentada a grupos pro-p de posto finito e homologia e cohomologia de grupos pro-pAbstract: In this work we study the main results presented by J. Wilson in his paper "Finite Presentations of Pro-p Groups and Discrete Groups", which extend the Golod-¿afarevi? Inequality to a large class of infinite pro-p and abstract groups. In the first chapter we present the basic theory of abstract free groups, focusing on finite presentations. Next we study profinite groups, with focus on pro-p groups. This study ranges from definitions to basic algebraic and topological properties, as well as the cases of finitely generated groups and the Frattini subgroup, and notions of completion, free pro-p groups, presentations of pro-p groups and completed group algebras. In the last chapter we study the main results regarding finite presentations of pro-p and abstract groups, which include soluble groups and implications on the structure of certain groups for which the Inequality holds. In the appendixes we briefly relate the presented theory to pro-p groups of finite rank and homology and cohomology of pro-p groupsMestradoMatematicaMestre em Matemátic

Nodosilinea hunanesis sp. nov. (Prochlorotrichaceae, Synechococcales) from a Freshwater Pond in China Based on a Polyphasic Approach

A cyanobacterial strain (ZJJ01), morphologically identified as a Leptolyngbya-like species was isolated from a freshwater pond in Zhangjiajie National Forest Park, China, and it was characterized through a polyphasic study based on morphological, ecological, and molecular data. Morphologically, the strain fits the description of Leptolyngbya well, but under further examination, it formed a distinctive structure, namely nodules, which confirmed that it belonged to the genus of Nodosilinea. The 16S rRNA gene threshold value and 16S rRNA phylogenetic analyses clearly confirmed that the studied strain belongs to the genus Nodosilinea but that it is phylogenetically distinct from the 10 other species of Nodosilinea. Furthermore, The D1&ndash;D1&rsquo; and Box&ndash;B helix of the 16S&ndash;23S ITS region of the strain ZJJ01 were also different from those of previously described Nodosilinea species. On the basis of this polyphasic approach, here, we provide a description of the new taxon: Nodosilinea hunanesis sp. nov