The facilitating role of phycospheric heterotrophic bacteria in cyanobacterial phosphonate availability and Microcystis bloom maintenance.

Background: Phosphonates are the main components in the global phosphorus redox cycle. Little is known about phosphonate metabolism in freshwater ecosystems, although rapid consumption of phosphonates has been observed frequently. Cyanobacteria are often the dominant primary producers in freshwaters; yet, only a few strains of cyanobacteria encode phosphonate-degrading (C-P lyase) gene clusters.

Phylogenomics Uncovers Evolutionary Trajectory of Nitrogen Fixation in Cyanobacteria.

Biological nitrogen fixation (BNF) by cyanobacteria is of significant importance for the Earth's biogeochemical nitrogen cycle but is restricted to a few genera that do not form monophyletic group. To explore the evolutionary trajectory of BNF and investigate the driving forces of its evolution, we analyze 650 cyanobacterial genomes and compile the database of diazotrophic cyanobacteria based on the presence of nitrogen fixation gene clusters (NFGCs). We report that 266 of 650 examined genomes are NFGC-carrying members, and these potentially diazotrophic cyanobacteria are unevenly distributed across the phylogeny of Cyanobacteria, that multiple independent losses shaped the scattered distribution.

The widespread capability of methylphosphonate utilization in filamentous cyanobacteria and its ecological significance.

Aquatic ecosystems comprise almost half of total global methane emissions. Recent evidence indicates that a few strains of cyanobacteria, the predominant primary producers in bodies of water, can produce methane under oxic conditions with methylphosphonate serving as substrate. In this work, we have screened the published 2 568 cyanobacterial genomes for genetic elements encoding phosphonate-metabolizing enzymes.

Comparative genomics reveals insights into cyanobacterial evolution and habitat adaptation.

Cyanobacteria are photosynthetic prokaryotes that inhabit diverse aquatic and terrestrial environments. However, the evolutionary mechanisms involved in the cyanobacterial habitat adaptation remain poorly understood. Here, based on phylogenetic and comparative genomic analyses of 650 cyanobacterial genomes, we investigated the genetic basis of cyanobacterial habitat adaptation (marine, freshwater, and terrestrial).

Prediction of different stages of rectal cancer: Texture analysis based on diffusion-weighted images and apparent diffusion coefficient maps.

Background: It is evident that an accurate evaluation of T and N stage rectal cancer is essential for treatment planning. It has not been extensively investigated whether texture features derived from diffusion-weighted imaging (DWI) images and apparent diffusion coefficient (ADC) maps are associated with the extent of local invasion (pathological stage T1-2 T3-4) and nodal involvement (pathological stage N0 N1-2) in rectal cancer.

Aim: To predict different stages of rectal cancer using texture analysis based on DWI images and ADC maps.

Cyanobacterial fossils from 252 Ma old microbialites and their environmental significance.

The end-Permian mass extinction was followed by the formation of an enigmatic rock layer with a distinctive macroscopic spotted or dendroid fabric. This deposit has been interpreted as microbial reef rock, digitate dendrolite, digital thrombolite, dendritic thrombolite, or bacterial deposits. Agreement has been reached in considering them as microbialites, but not in their formation.

[Dianchi Lake macroinvertebrate community succession trends and retrogressive analysis].

Historical records and data from yield surveys conducted in 2009 and 2010 were used to investigate macroinvertebrate community succession trends in Dianchi Lake. Species richness has declined from 57 in the 1980s to 32 in 2010, representing a species loss of 44%. Among the major benthic groups, the highest rate of loss was recorded for mollusks (75%) and aquatic insects (39%).

[Recruitment ability of Microcystis aeruginosa under low light-low temperature combination].

The responses of growth and PS II activities in Microcystis aeruginosa (FACHB 905) have been studied under a condition of low light-temperature combination use orthogonal experiment method. The contents and proportions of chlorophyll and carotenoid were determined by colorimetry, the PS II activities were assayed with a Water-PAM, and also, the photosynthesis recovery of M. aeruginosa was verified via reculture under a normal condition.

Quantitative assessment of toxic and nontoxic Microcystis colonies in natural environments using fluorescence in situ hybridization and flow cytometry.

Toxic cyanobacterial blooms constitute a threat to human safety because Microcystis sp. releases microcystins during growth, and particularly during cell death. Therefore, analysis of toxic and nontoxic Microcystis in natural communities is required in order to assess and predict bloom dynamics and toxin production by these organisms.

Characterization of a monomeric heat-labile classical alkaline phosphatase from Anabaena sp. PCC7120.

Alkaline phosphatases (APs), known inducible enzymes of the Pho regulon and poorly characterized in cyanobacteria, hydrolyze phosphomonoesters to produce inorganic phosphate (P(i)) during P(i) starvation. In this study, two predicted alkaline phosphatase genes in the genome of Anabaena sp. PCC 7120, all2843 and alr5291, were apparently induced during P(i) starvation.

[Physiological character and the ratio of the sinking Microcystis in Lake Dianchi].

Aimed to explore the relationship between Microcystis cells sinking and water bloom development, the physiological status of the sinking cells was characterized by comparing with the floating cells. The sinking ratio and the 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide (MTT) staining were also employed in surface and bottom samples to substantiate the character. The dynamics of the sinking ratio and the chlorophyll a concentration were also compared.

[One step time-resolved fluorescence immunoassay for direct estimation of microcystins].

A direct-competitive time-resolved fluorescence immunoassay (TRFIA) for microcystin detection was established, which was based on europium labeled MCLR-BSA conjugant and microtiter plates coated with anti-mouse IgG. The optimal dilution of europium labeled MCLR-BSA conjugant is 1/50 and most appropriate titration of anti-microcystin-LR (MCLR) monoclonal antibodies is 100 ng/mL. The standard curve under the optimal conditions shows that the quantitative range is from approximately 0.

Response of microcystis to copper stress: do phenotypes of microcystis make a difference in stress tolerance?

To elucidate the role of phenotype in stress-tolerant bloom-forming cyanobacterium Microcystis, two phenotypes of M. aeruginosa - unicellular and colonial strains were selected to investigate how they responded to copper stress. Flow cytometry (FCM) examination indicated that the percents of viable cells in unicellular and colonial Microcystis were 1.

[Microcystin-LR induces apoptosis in L-02 cell line].

Objective: To investigate the toxicological mechanism of microcystin-LR (MCLR) on L-02 cells.

Methods: L-02 cells was treated with MCLR at different concentrations and the subsequent changes such as cell proliferation (MTT assay), morphology, lactate dehydrogenase (LDH) leakage, apoptosis rate and apoptosis-related gene expression were examined.

Results: MTT assay showed that MCLR mildly inhibited the cell growth within the initial 24 h of treatment but enhanced the cell viability after that till 60 h in a time- and dose-dependent manner.

[Acute toxicity of microcystin-LR in BALB/c mice].

Objective: To investigate acute toxicity of microcystin-LR in BALB/c mice.

Methods: BALB/c mice were subjected to intraperitoneal injection of microcystin-LR at the half lethal dose (LD50) and 1/2 LD50, and the organ weight indices and various biochemical indices were determined 30 min and 4 h after the treatment, respectively.

Results: Significant increase in liver or kidney weight index occurred in the treated mice, indicating hemorrhagic conditions of the two organs.

Reactive oxygen species and antioxidant enzymes activity of Anabaena sp. PCC 7120 (Cyanobacterium) under simulated microgravity.

It was found that reactive oxygen species in Anabaena cells increased under simulated microgravity provided by clinostat. Activities of intracellular antioxidant enzymes, such as superoxide dismutase, catalase were higher than those in the controlled samples during the 7 days' experiment. However, the contents of glutathione [correction of gluathione], an intracellular antioxidant, decreased in comparison with the controlled samples.

An ELISA-like time-resolved fluorescence immunoassay for microcystin detection.

Background: A time-resolved fluorescence immunoassay (TRFIA), based on anti-microcystin-LR (MCLR) monoclonal antibodies (MAbs) and europium-labeled antimouse IgG conjugate, was first developed for microcystin detection.

Methods: Anti-MCLR MAbs were prepared by a standard method, and the attained MAbs showed a good cross reactivity with MCLR, MCRR and MCYR. The TRFIA was performed in an indirect competitive mode.

[Lipid peroxidation in microalgae cells under simulated microgravity].

Objective. To provide direct evidences for effects of microgravity on structure and function of plasma membrane. Method.