Biology and conservation of the genus Scylla in India subcontinent.

Mud crabs usually inhabit brackish water bodies of South-East Asia including India. The biological significance of the species is its survibility in wide range of hydro-biological fluctuating environments including salinity. The life cycle of the species includes two important larval stages at which they are vulnerable to various predators. Pathophysiological status of the species is a challenge for its aquaculture. Inspite of a huge economical and high food values, informations on biochemical, molecular, physiological, ecological and taxonomical aspects of mud crabs (Scylla sp.) in comparison to other important aquaculture candidates are very limited. The present review is an attempt to string together various informations available on mud crabs (S. serrata) so that it will provide a platform to have all the basic informations regarding the species for interested workers. It is believed that understanding the pathology, ecophysiology, genetics and reproduction of the species in its natural environment will not only help in its conservation but also will help in its enhanced production.

Effect of T3 treatment on glutathione redox pool and its metabolizing enzymes in mitochondrial and post-mitochondrial fractions of adult rat testes.

T3 (3,3', 5-triiodo-L-thyronine; 20 microg/100 g body weight/day in 0.01 N NaOH, i.p for 1, 3 and 5 days) treatment modulated reduced (GSH) and oxidized (GSSG) glutathione contents along with the activities of its metabolizing enzymes (such as glutathione peroxidase, glutathione reductase and glutathione S-transferase) in the testis of Wistar rats. However, the magnitude and nature of changes in the above biochemical parameters in response to T3 treatment were noticed to be different between mitochondrial and post-mitochondrial fractions. This was accompanied with elevated levels of lipid hydroperoxide and ascorbic acid in the crude homogenate of testis. The level of hydrogen peroxide in the post-mitochondrial fractions of testes did not change on first day, decreased on 3rd day and increased on 5th day of the hormone treatment when compared to respective controls. Nevertheless, its content in mitochondria was significantly elevated in response to all the three durations of the hormone treatment having the highest induction on 3rd day. The changes observed in the levels of GSH and GSSG and its metabolizing enzymes in response to T3 treatment reflect an alteration in the redox state of testis, which may be a causative factor for the impairment of testicular physiology as a consequence of oxidative stress.

Kinetics and mechanism of reduction of ferricytochrome c by glutathione and L-cysteine: a comparative study.

The kinetics and mechanism of the reduction of ferricytochrome c [Cyt c(III)] by substrates namely glutathione (GSH) and L-cysteine (L-cys) have been investigated spectrophotometrically employing [substrate]T > [Cyt c(III)]T. The reaction exhibits first order dependence in [substrate]T and [Cyt c(III)]T. The pseudo-first order rate constant increases with an increase in pH, indicating that the conjugate base form of the HCyt c(III) is a better oxidant than the parent HCyt c(III). The electron transfer rate constants between the oxidants and GSH for both the k1 and k2 paths are found to be greater than that with L-cysteine. Hence, GSH is a better reductant of Cyt c(III) as compared to L-cysteine. A suitable mechanism has been proposed on the basis of experimental findings. The deprotonation constant for HCyt c(III) and the second order rate constants of k1 and k2 paths for the present reaction at 25 degrees C have been determined.

Experimental hyperthyroidism-induced oxidative stress and impairment of antioxidant defence system in rat testis.

Short-term hyperthyroidism, induced by daily administration of T3 (20 microg/100g body weight) for one, three, and five days consecutively, modulates oxidative stress and antioxidant defence parameters in mitochondrial and postmitochondrial fractions of testis in adult rats. Alteration in antioxidant defences along with oxidative stress parameters in testis by thyroid hormone was found to be associated with a decline in the number of sperms and disturbances in histoarchitecture of seminiferous tubules in the testes; the results indicated that induced hyperthyroid state altered testicular physiology by influencing antioxidant defence system of testes.

Effects of hypothyroidism induced by 6-n-propylthiouracil and its reversal by T3 on rat heart superoxide dismutase, catalase and lipid peroxidation.

The present study critically evaluates the effects of hypothyroid and hyperthyroid states on lipid peroxidation and two enzymes of active oxygen metabolism, namely superoxide dismutase (SOD) and catalase (CAT) in the rat heart mitochondrial and post-mitochondrial fractions. Lipid peroxidation, an index of oxidative stress, was elevated in the heart tissue in hypothyroid state but reduced upon T3 supplementation. Hyperthyroidism registered increased SOD activity in post-mitochondrial fraction. Mitochondrial SOD activity was reduced in hypothyroid state, which was further reduced by T3 administration. In contrast, different thyroid states had no effect on catalase activity in the mitochondrial fraction. The hypothyroid state however, significantly augmented catalase activity in post-mitochondrial fraction. The results suggest that the antioxidant defence status of cardiac tissue is well modulated by thyroid hormone.

Specific limb abnormalities induced by hydrogen peroxide in tadpoles of Indian jumping frog, Polypedates maculatus.

Hydrogen peroxide (H2O2), one of the reactive oxygen intermediates (ROI) and a potential inducer of nuclear transcription factors induces consistent type of abnormal limb development (truncated with bent skeletal elements) in the tadpoles of Indian jumping frog, Polypedates maculatus.

In vitro stimulation of chick brain lipid peroxidation by aluminium, and effects of tiron, EDTA and some antioxidants.

In vitro effect of aluminium (Al) on Fe(2+)-induced lipid peroxidation (LPX) in various subcellular fractions from the cerebral hemispheres (CH) of 7- and 30-day old chicks was studied. Stimulation of Fe(2+)-induced LPX by Al was observed to be the highest in microsomal fraction. The magnitude of elevation of Fe(2+)-induced LPX in various subcellular fractions of brain showed age related variation. Of the six chemicals tested for their influence on Al-induced lipid peroxidation, both doses of 1,2-dihydroxybenzene-3,5-disulphonic acid disodium salt (Tiron), ethylene diamine tetra acetic acid disodium salt (EDTA), and ascorbic acid prevented the Al-induced LPX in crude homogenates of the CH, whereas only at a higher dose inhibition by 1,4-diazabicyclo (2.2.2.) octan (DABCO) was observed. On the contrary, mannitol and dimethyl sulfoxide did not inhibit the induction of LPX by Al in crude homogenate. The effect of test chemicals on Al-induced LPX in both the ages of chick tissue was almost similar. The results suggest that Al further augments Fe(2+)-induced LPX in various compartments of the cell due to generation of free radicals. The results also showed that Tiron, EDTA and antioxidants, such as ascorbic acid and DABCO can prevent LPX induced by Al.

Age-related differences of hexachlorocyclohexane effect on hepatic oxidative stress parameters of chicks.

Acute hexachlorocyclohexane (HCH; 50 mg/kg body wt, i.p.) treatment in young (30-day-old) chicks resulted in elevation of lipid peroxidation (LPX) only in nuclear fractions of livers while the same treatment in immature (7-day-old) chicks resulted in elevation of LPX in various liver subcellular fractions. Treatment of various subcellular fractions of livers with HCH in vitro stimulated increased LPX in young chicks than in immature ones. Hepatic cytoplasmic CN-sensitive and -resistant superoxide dismutase activities in immature chicks were inhibited significantly by HCH but no effect was observed in case of young chicks. The pesticide treatment in both immature and young chicks did not influence hepatic catalase activity. The level of glutathione in the liver of young chicks increased in response to the pesticide treatment but remained unaffected in the case of immature chicks. The results of the present study show that HCH-induced changes in hepatic oxidative stress parameters in chicks are age dependent.

Hexachlorocyclohexane-induced changes in lipid peroxidation, superoxide dismutase and catalase activities and glutathione content in chick liver.

An elevation in the level of lipid peroxides in nuclear, mitochondrial and microsomal fractions of chick liver was recorded 6 hr after hexachlorocyclohexane (HCH; 50 mg/kg body wt., ip) treatment. The magnitude of increase remained more or less same even 24 hr after the pesticide treatment. Total glutathione content also increased by 6 hr of HCH treatment and did not change even 24 hr after the pesticide treatment. Protein content of crude homogenate and 10000 g supernatant decreased significantly 6 hr after the pesticide treatment. The magnitude of decrease was more or less same even 24 hr after the pesticide treatment. Although cytoplasmic superoxide dismutase and catalase activities (expressed as units/mg protein) did not change 24 hr after HCH treatment, a small but significant increase in superoxide dismutase activity was recorded 6 hr after HCH treatment. On the other hand when activities were expressed as units/mg tissue wt., a significant decrease in the activities of both the enzymes was recorded 6 and 24 hr after HCH treatment. Therefore, the decrease in the activities of both the enzymes in response to HCH in chick liver may be due to decrease in tissue protein content in general rather than specific decrease in the activities of the enzymes.

Follicular growth rate and lack of influence of oestradiol valerate, testosterone propionate and aminoglutethimide phosphate on ovarian follicular development in the musk shrew, Suncus murinus L.

Growth rate of follicles and effects of administration of oestradiol valerate (EV), testosterone propionate (TP) and aminoglutethemide phosphate (AGP) on the development of ovarian follicles of the adult musk shrew were investigated. The follicular growth rate was estimated by mitotic index before and 2 hr after colchicine treatment to the shrews. Mitotic index of granulosa cells increased linearly with the increase in the follicular diameter. The calculated mean duration of mitosis was 0.48 hr. The mean time taken for follicle to pass from primary follicle stage to preovulatory stage was estimated to be 12 days. Treatment of both the steroids EV and TP, failed to produce any noticeable effect on the atretic follicle of the musk shrew. The results indicate that neither EV or TP, nor the potent steroid inhibitor AGP had any influence on the growth of large follicles in this primitive eutherian mammal.