Low dose and subchronic Aroclor 1254 induced histopathological changes in mice kidney

Present communication reports the low dose and subchronic duration-dependent histopathological changes afterexposure to Aroclor 1254 in the kidney tissue of Swiss albino mice. Polychlorinated biphenyls (PCBs) like Aroclor1254 congeners accumulate in tissues rich in lipids and remain inside for a long time, affecting the functionality of thecells in direct and indirect ways. The most commonly observed effects were skin ailments such as chloracne, rashes,and effects on kidney functions. Animal studies indicated that PCBs could affect the functionality of the kidney,thyroid, immune, and endocrine systems. Separate groups of mice were subjected to a daily oral dose of 0.1 mg/kgbody weight (BW)/day and 1 mg/kg BW/day Aroclor 1254, dissolved in corn oil, for four subacute exposure durations(7, 14, 21, and 28 days). Control groups were received only the corn oil (vehicle). Results revealed mainly exposureduration-dependent histopathological lesions such as dilation of the tubular cells, fragmentation of cytoplasm andloss of nuclear materials, formation of large vacuoles inside the cells, and necrosis even at very low doses of Aroclorintoxication. The present study reports predominantly exposure duration-dependent histopathological effects ofAroclor 1254 in the kidney tissue of mice. The study suggested that the subacute exposure to low doses of Aroclor1254 could cause significant irreparable structural deformities in the renal cells of the kidney tissue. Results alsoshowed that renal tubular cells were more affected showing severe necrosis

Effects of low concentrations of a polychlorinated biphenyl, Aroclor 1254 on membrane bound ion dependent ATPases in mice liver.

Aroclor 1254, a polychlorinated biphenyl, is present in the environment in low concentration but references on its toxic effects on liver cell membrane proteins and the mechanism of actions are not abundantly available. Therefore, the present study was undertaken to investigate the low level, sub-acute dose and exposure duration dependent effects of Aroclor 1254 on total, Na+, K+, Ca2+ and Mg2+-ATPases of the mouse liver. The hypotheses tested in the present study were, (a) whether the low, environmentally available dose and the exposure durations of Aroclor 1254 affects the membrane-bound ion dependent ATPases, and (b) if a response was observed, whether it is a direct or indirect effects of the toxicant. Groups of mice were exposed to different doses (0.1 and 1mg kg-1 body weight d-1) and exposure durations (4 d, 8 d and 12 d) of Aroclor 1254. The results indicated significant exposure duration dependent changes in the specific activity of the selected membrane bound ATPases. As the observed changes were mostly enzyme stimulation after toxication through oral administration, the effects of the Aroclor were possibly indirect, through complex chain of reactions.

Movement and bioaccumulation of chromium in an artificial freshwater ecosystem.

In the present study, a small fresh water aquatic ecosystem was created into a small test tank to evaluate the movement and bioaccumulation of Cr (VI) through water, sediment, a macrophyte Hydrilla, small fish guppy, and few key organs of magur, Clarias batrachus. The Cr (VI) intoxication was imposed of as a single dose of 30 mg/l concentration for a wide range of exposure durations like 1, 7, 14 and 21 days. After 1 day of exposure the total Cr (VI) load was very high in the water and sediment samples (5.187 microg/ml and 23.332 microg/g respectively) which were decreased with increasing exposure durations over their respective controls. In samples of macrophyte, Cr (VI) concentration showed a gradual increasing trend from 6.1797 microg/g in control to 21.1903 microg/g in 1 day exposure and reached up to 24.635 microg/g after 21 days exposure. In guppy, the Cr (VI) bioaccumulation showed an increasing trend but the rate was not statistically significant. However, in magur, the Cr (VI) uptake showed a significant gradual and increasing trend with increasing exposure durations in liver, brain, intestine and muscular tissues than gill and kidney over their respective controls. The movement of the Cr (VI) was found to be from sediment to water during pre-treatment phase, after intoxication, from water to macrophyte and to other phytoplankton and zooplankton. It then accumulated in the primary consumer guppy and finally moved to the secondary consumer the magur following the food web. The results reveal that the rate of movement and bioaccumulation of Cr (VI) varied from organism to organism and in C. batrachus, from tissue to tissue.

Regional variations in fibre growth dynamics of myotomal and caudal fin muscles in relation to body size of a freshwater teleost, Barbus sarana (Cuv. & Val.).

The growth of red fibres in anterior and middle myotomal regions of B. sarana was mainly by hyperplasia in smaller size classes. In higher size classes, growth by hyperplasia was greater in posterior myotomal region compared to the other two myotomal regions. The growth of pink fibres in anterior myotomal regions was mainly by hypertrophy. The middle and posterior myotomal regions showed fibre growth by hyperplasia. The growth dynamics of white fibres revealed more or less similar pattern in all three myotomal regions against the somatic development. White fibres grew by hyperplasia up to 8 cm F.L. size classes and thereafter by hypertrophy. However, in > 12 cm F.L. size classes, the mean diameter of white fibres did not increase significantly. Similar pattern of growth was found in the white fibres of caudal fin muscle. It is interesting to note that the hyperplasia was mostly completed in the white fibres of the smallest fish studies, whereas, it continued to quite larger fish size in red and pink fibres. Thus, hyperplasia and hypertrophy may be responsible for growth in all fibre types in all myotomal regions in relation to somatic development in this small and medium growing species.