Effects of sodium hypochlorite treatment on the chlorophyll fluorescence in photosystem II of microalgae.

Chlorophyll fluorescence-based method shows great potentials for on-site assessing the vitality of algae in treated ship's ballast water. However, there is very limited information on the mechanism of chlorophyll fluorescence in photosystem II (PSII) after the NaClO treatment. In this paper, the effects of NaClO treatments with five concentrations (0.01, 0.04, 0.08, 0.12 and 0.15 mg/L) and treating periods (6, 24 and 48 h) on the chlorophyll fluorescence kinetics and spectra of Chlorella vulgaris (C. vulgaris) and Platymonas helgolandica (P. helgolandica) were investigated. Experimental results showed that both exposure time and dose were important factors that affect the toxicity of NaClO to microalgae. Further analyses showed that the maximum photochemical quantum yield of PSII, photochemical quenching and yield decreased rapidly with the increase in NaClO concentrations in the range of 0.04 mg/L to 0.15 mg/L, suggesting that NaClO seriously inhibited PSII reaction centers of algae. In addition, the maxima value of fluorescence at excitation wavelength still appeared near 437 nm and 468 nm under NaClO stress, pointing to the pigments for fluorescence produced by algae were mainly chlorophyll a and chlorophyll b antenna. As compared to chlorophyll a, the relative fluorescence intensity of chlorophyll b decreased significantly in the all of NaClO treatments. According to the fluorescence emission spectra, treatment of NaClO resulted in a shift of the maximum peak of C. vulgaris and P. helgolandica from 685.2 nm to 681.9 nm and 685.2 nm to 680.5 within 6 h, respectively. This indicates that the structure of antenna light-absorbing pigments of PSII changed under NaClO stress. These results revealed that the chlorophyll fluorescence mechanism in PSII of damaged microalgae occurred variation, which was important for the reliable application of on-site analysis of ballast water indicator based on chlorophyll fluorescence detection.

Concise perspectives on some synthetic thiazolidine-2,4-dione derivatives and their specific pharmacodynamic aspects.

Glitazones are synthetic derivatives of thiazolidinedione, and are designated as oral anti-diabetic agents, primarily acting on peroxisome proliferator-activated receptor-gamma (PPAR-γ) receptors and driving some crucial metabolic pathways linked to glucose and lipid metabolism at transcriptional level. Despite presenting adverse effects, including weight gain, fluid retention, prostate hyperplasia, hyperinsulinemia, and myocardial infarction, they are still preferred in clinical settings due to their utmost efficacy and selectivity. However, these complications kept glitazones restrained for long-term usage. The present review briefly highlights some important synthetic derivatives of thiazolidine2,4-dione and emphasizes the influence of various structural manipulations on their bio-efficacy.