Alterations of organ histopathology and metallolhionein mRNA expression in silver barb,Puntius gonionotus during subchronic cadmium exposure

Common silver barb, Puntius gonionotus, exposed to the nominal concentration of 0.06 mg/L Cd for 60 d, were assessed for histopathological alterations （gills, liver and kidney）, metal accumulation, and metallothionein （MT） mRNA expression. Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae, vacuolization in hepatocytes, and prominent tubular and glomerular damage in the kidney. In addition, kidney accumulated the highest content of cadmium, more than gills and liver. Expression of MT mRNA was increased in both liver and kidney of treated fish. Hepatic MT levels remained high after fish were removed to Cd-free water. In contrast, MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water. The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.

Phytoextraction of Metal Contaminants by Typha Angustifolia: Interaction of Lead and Cadmium in Soil-Water Microcosms

A greenhouse study was conducted on phytoextraction and accumulation of lead (Pb) and cadmium (Cd) from contaminated soil – water microcosms by the narrow-leaved cattail, Typha angustifolia. The plants were grown in sandy loam soil containing 1,666 and 38.5 mg/L of Pb(NO3)2 and Cd(NO3)2 respectively. The trends of lead and cadmium by T. angustifolia for all soil – water microcosms suggested interaction effects as decreased soil lead concentrations and increased water cadmium concentrations over time. T. angustifolia expressed trends as increased biomass in all contaminated shoots and roots examined. Cadmium uptake in shoot and root biomass slightly decreased when lead was initially added to the soil but cadmium uptake in root biomass increased after 30 days. Data suggested an interaction between lead and cadmium and possible that lead uptake was inhibited when cadmium was present.

Evaluations of larvicidal activity of medicinal plant extracts to Aedes aegypti （Diptera： Culicidae） and other effects on a non target fish

A preliminary study was conducted to investigate the effects of the extracts of 112 medicinal plant species, collected from the southern part of Thailand, on Aedes aegypti. Studies on larvicidal properties of plant extracts against the fourth instar larvae revealed that extracts of 14 species showed evidence of larvicidal activity. Eight out of the 14 plant species showed 100% mosquito larvae mortality. The LC50 values were less than 100μg/mL （4.1μg/ mL-89.4μg/mL）. Six plant species were comparatively more effective against the fourth instar larvae at very low concentrations. These extracts demonstrated no or very low toxicity to guppy fish （Poecilia reticulata）, which was selected to represent most common non-target organism found in habitats ofAe. aegypti, at concentrations active to mosquito larvae. Three medicinal plants with promising larvicidal activity, having LC50 and LC50 values being 4.1 and 16.4 μg/mL for Mammea siamensis, 20.2 and 34.7 μg/mL forAnethum graveolens and 67.4 and 110.3μg/mL forAnnona muricata, respectively, were used to study the impact of the extracts on the life cycle ofAe. aegypti. These plants affected pupal and adult mortality and also affected the reproductive potential of surviving adults by reducing the number of eggs laid and the percentage of egg hatchability. When each larval stage was treated with successive extracts at the LC50 value, the first instar larvae were found to be very susceptible to A. muricata and the second instar larvae were found to be susceptible to A. graveolens, while the third and fourth instar larvae were found to be susceptible to M. siamensis. These extracts delayed larval development and inhibited adult emergence and had no adverse effects on P. reticulata at LC50 and LC50 values, except for the M. siamensis extract at its LC50 value.

Phytoremediation potential of charophytes:Bioaccumulation and toxicity studies of cadmium,lead and zinc

The ability for usage of common freshwater charophytes,Chara aculeolata and Nitella opaca in removal of cadmium （Cd）,lead （Pb） and zinc （Zn） from wastewater was examined.C.aculeolata and N.opaca were exposed to various concentrations of Cd （0.25 and 0.5 mg/L）,Pb （5 and 10 mg/L） and Zn （5 and 10 mg/L） solutions under hydroponic conditions for 6 days.C.aculeolata was more tolerant of Cd and Pb than N.opaca.The relative growth rate of N.opaca was drastically reduced at high concentrations of Cd and Pb although both were tolerant of Zn.Both macroalgae showed a reduction in chloroplast,chlorophyll and carotenoid content after Cd and Pb exposure,while Zn exposure had little effects.The bioaccumulation of both Cd and Pb was higher in N.opaca （1544.3 μg/g at 0.5 mg/L Cd,21657.0 μg/g at 10 mg/L Pb） whereas higher Zn accumulation was observed in C.aculeolata （6703.5 μg/g at 10 mg/L Zn）.In addition,high bioconcentration factor values （〉 1000） for Cd and Pb were observed in both species.C.aculeolata showed higher percentage of Cd and Pb removal （〉 95%） than N.opaca and seemed to be a better choice for Cd and Pb removal from wastewater due to its tolerance to these metals.