ABSTRACT
Polycyclic aromatic hydrocarbons [PAHs] in the priority controlling list of US EPA were systematically evaluated in surface sediments in Dianchi Lake and its estuaries. Total PAH concentrations [IPAHs] varied from 210 to 11,070 ng/gdry weight [d.w] in Dianchi Lake, and from 230 to 12,271 microg/g d.w. in the estuaries. IPAHs in sediments from Caohai section were higher than those from Waihai section. The occurrences of PAHs in the Lake were closely related to the distributions of rivers, indicating that the river runoff was an important pathway of PAHs into the Lake. Compared with the US Sediment Quality Guidelines [SQGs], IPAHs in most area were below the effect range low [ERL], which implied that the adverse biological effects would occur rarely. The toxic equivalent concentrations of potentially carcinogenic PAHs [TEQ[carc]] varied from 19to967ngTEQ/gd.w., and the higher values were found in northern Caohai area. The proportions of the toxic equivalent quantity [TEQ[carc]] to the total TEQs in sediments were all above 96%, suggesting that the carcinogenicity of PAHs could be occurred. Significantly positive correlations between total organic carbon [TOC] and less molecular weight PAHs [2, 3-ring] [LPAHs] were observed in the Lake. Diagnostic ratios showed that the primary source of PAHs in Dianchi Lake and most estuaries is biomass combustion, but is petroleum combustion or petrogenic origin in several other estuaries
ABSTRACT
Toxoplasmosis is one of the most common parasitic infections of humans and other mammals. This study was aimed to understand the mechanism of action of veterinary medicine-sulfachloropyrazine [SPZ, 99.97%] against Toxop/asma gondii. T. gondii tachyzoites were soaked in PBS [as a control] or SPZ [250 mg/mL] for 2 h at 37 °C. After being processed, any ultrastructural changes of the tachyzoites that had occurred were observed by Scanning Electron Microscopy [SEM] and Transmission Electron Microscopy [TEM]. The tachyzoites from control groups with a uniform size had a smooth surface and intact cell or nuclear membranes. In addition, an oval-shaped nucleus, conoids and micronemes were also observed. By contrast, many parasites from the SPZ-treated groups were detrimentally affected by the treatment. Some appeared to be of the vacuolization in their cytoplasm, with the substantial reduction in the number of dense granules and the blur of some organelles. The morphology and ultrastructure of tachyzoites can be affected significandy by SPZ, which might kill the parasite by inhibiting its energy metabolism, inducing apoptosis and damaging its structure. The study provides an experimental basis for further study on the mechanism of SPZ against T. gondii