Gastrointestinal toxicity induced by microcystins.

Microcystins (MCs) are produced by certain bloom-forming cyanobacteria that can induce toxicity in various organs, including renal toxicity, reproductive toxicity, cardiotoxicity, and immunosuppressive effects. It has been a significant global environmental issue due to its harm to the aquatic environment and human health. Numerous investigators have demonstrated that MC exposure can induce a widespread epidemic of enterogastritis with symptoms similar to food poisoning in areas close to lakes. Both in vivo and in vitro studies have provided evidence of positive associations between MC exposure and gastrointestinal toxicity. The toxicity of MCs on the gastrointestinal tract is multidimensional. MCs can affect gastrointestinal barrier function and shift the structure of gut microbiota in different gut regions. Furthermore, MCs can inhibit the secretion of gastrointestinal digestive enzymes and the release of inflammatory cytokines, which affects the expression of immune-related genes in the intestine. The damage of the intestine is closely correlated to MC exposure because the intestine is the main site for the digestion and absorption of nutrients. The damage to the gastrointestinal tract due to MCs was summarized from different aspects, which can be used as a foundation for further exploration of molecular damage mechanisms.

[Research in the relation between telomerase reverse transcriptase expression in spermatogenic cells and serum levels of estradiol of fluorotic rats].

OBJECTIVE: To study the relation between telomerase reverse transcriptase (TERT) activity expression in spermatogenic cells and serum levels of estradiol of fluorotic rats. METHODS: We randomly divided thirty SD male rats into control group, low-dose group and high-dose group, then inject sodium fluoride (0, 10, 20 mg/kg bw) into celiac of rats. We respectively observed changes of estrogen and TERT using methods of radioimmunoassay, in situ hybridization. In addition, we observed the quality of spermatozoa. RESULTS: The level of estrogen, the expression of telomerase and the number and the livability of the spermatozoon in low-dose and high-dose fluorotic rats were lower than those of control rats (P < 0.05). Therefore,the above indexes decreased with the increase of dosage. In addition, sperm aberration of each fluorotic group was higher than control group (P < 0.05). And it increased with the increase of dosage. The content of E2 in serum of different fluoride treatment groups was positively correlated with the expression of telomerase in seminiferous tubule significantly, respectively (low-dose fluoride treatment groups, r = 0.941, P < 0.01, high-dose fluoride treatment groups, r = 0.929, P < 0.01). CONCLUSION: NaF possibly damaged the male reproductive system by the approach of E2/ER-TERT-spermatozoon, relation between TERT expression in spermatogenic cells and serum levels of estradiol is positive correlation.

[Investigation of algae pollution in Xiliu Lake and identification of toxic cyanobacteria by whole-cell PCR].

OBJECTIVE: To investigate the contaminative condition of the floating algae (especially toxic cyanobacteria) in Xiliu Lake, and establish a whole-cell PCR method for identifying the toxic cyanobacteria. METHODS: The surface water of Xiliu Lake was sampled by plastic sampler from March, 2004, and the number of algae was counted by using blood cell counter. The phycocyanin intergenic spacer region (PC-IGS) and microcystin synthetase gene B (mcyB) were identified by whole-cell PCR in water samples, and the amplified product of mcyB was inserted into T vector and sequenced. RESULTS: Cyanobacteria, Chlorophyta, Bacillariophyta and Euglenophyta were main algae, and cyanobacteria was the dominant algae in summer and autumn. From July 7 to September 27,2 004, PC-IGS was detected positively in 11 samples, and from July 29 to September 27, mcyB was-detieted positively in 9 samples. Compared with the reported mcyB of Microcystis aeruginosa in Genbank, the homology of gene sequence was more than 97 t he homology of amino acid sequence was more than 94%. CONCLUSION: In summer and autumn toxic cyanobacteria could be detected in Xiliu Lake. Toxic cyanobacteria could be identified successfully by whole-cell PCR.