Rahul Kundu

Effects of chromium(VI) on some ion-dependent ATPases in gills, kidney and intestine of a coastal teleost Periophthalmus dipes.

The coastal teleost species, Periophthalmus dipes, commonly known as the mudskipper, was exposed to three sublethal concentrations (5, 10 and 15 mg/l) of potassium chromate for three exposure durations (2, 4 and 6 days). The study compares the dose- and duration-dependent effects of Cr(VI), as potassium chromate, on the ATPase systems in various organs of this fish species. In this study, effects of Cr(VI) stress on total ATPase, (Na+,K+)-ATPase, (Ca+2)-ATPase, (Mg+2)-ATPase, (Ca+2, HCO3-)-ATPase and (Mg+2,HCO3-)-ATPase in gills, kidney and intestine were estimated. A general dose- and duration-dependent inhibitory trend was observed. However, it is evident that exposure duration is more important then dose in the inhibition of the activity of the enzymes. At some concentrations, initial stimulation of the activity of some enzymes were also noticed. However, maximum inhibition was observed in higher Cr(VI) concentrations exposed for the longest time. It is possible that this inhibition of the ATPases by Cr(VI) blocked the active transport system of the gill epithelial as well as chloride cells, glomerular and epithelial cells of the tubules and thus altered the osmoregulatory mechanism of the fish. It appears that this heavy metal ion alters the membrane permeability of the intestinal epithelial cells and other layer of cells by altering the activity of ATPases, resulting in a breakdown of the active transport mechanism needed for the absorption of nutrients, ions and metabolites.

Mercuric chloride-induced inhibition of different ATPases in the intestine of mudskipper, Boleophthalmus dentatus

This paper deals with the toxicity of mercuric chloride to different ATPases in the intestine of mudskipper (Boleophthalmus dentatus). Mudskippers were exposed to four sublethal concentrations of mercuric chloride for three durations. The specific activities of Na+, K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase, Ca2+, HCO3(-)-ATPase, and Mg2+, HCO3(-)-ATPase were estimated. There was linear inhibition of all the enzymes with increasing mercuric chloride concentration as well as exposure duration. The Na+,K(+)-ATPase was found to be the enzyme most affected, followed by other ion-dependent ATPases. Inhibition of all the enzymes indicates severe damage to the intestinal cells, resulting in a blockage of the transport of substances across the membrane.

Seasonal variations in the water quality, diversity and population ecology of intertidal macrofauna at an industrially influenced coast

Present communication reports the physico-chemical and biological quality of seawater and status of benthos of a highly industrialized shore of the north-western coastline of India. The coastal area considered for the present study, encircled by a variety of industries, was divided into two sampling sites and monitored for two consecutive years. Results of the water quality suggest that the obtained values of the physical and chemical parameters of seawater were comparable with data reported earlier. However, data obtained in the biological parameters of the seawater showed a declining trend. Results of the intertidal macrofaunal diversity studies revealed that the muddy upper littoral zones were represented by few species of coelenterata, porifera, arthropoda and mollusca. In the rocky-muddy middle littoral zones, gastropods, stars fishes, corallites, crabs, polychetes and tubeworms were present, whereas, predominantly rocky lower littoral zones were comparatively rich in macrofaunal diversity with small patches of coral colonies. However, when the results obtained in the present study was compared with that of earlier reported data, it was clear that the macrofaunal diversity indeed declined considerably over the years. This may be due to habitat destruction and habitat alteration in the coastline caused by increased anthropogenic activities in the area. Seasonal variations in the population density and abundance were observed in most of the faunal groups except in sessile corals and sponges. This may be due to local migration of the faunal groups towards deeper regions of the Gulf, as supported by the analysis of similarity, to avoid influx of freshwater during monsoon, and high temperature during summer and post monsoon seasons. The overall assessment of different parameters of this study revealed that though the physico- chemical characteristics of the seawater did not varied much from the earlier reported status, the biological characteristics of the seawater and intertidal zone was affected possibly by a high degree of anthropogenic pressure.

SHORT-TERM PCB (AROCLOR 1254) TOXICITY ON FEW PHOSPHATASES IN MICE BRAIN

The present communication reports the dose and duration dependent toxicity of a PCB, Aroclor 1254, to a few ion dependent ATPases, Acid phosphatase, Alkaline phosphatase and Glucose-6-phosphatase in the whole brain tissue of mice. Two groups of mice were subjected to two sublethal doses (0.1 and 1 mg kgbw−1 day−1) of PCB orally and exposed for 4, 8 or 12 days. A separate control group received the corn oil vehicle for the same exposure times. The observed results indicated exposure duration dependent changes in the enzymatic levels in the brain. The results suggest that the alteration in the enzymatic activity was possibly due to imposed oxidative stress generated by Aroclor 1254 on membrane-bound ion-dependent ATPases and other phosphatases in the brain tissue.

Effects of Low Dose Dioxin on Membrane Bound Ion Dependent ATPases in Mice Kidney

The present communication reports the dose and exposure dependent effects of a dioxin on few ion dependent membrane bound ATPases of mice kidney. Effects of TCDD on the specific activity of few membrane bound ATPases viz., Total ATPase, Na + K + ATPase, Ca ++ ATPase, Mg ++ ATPase, Ca ++ , HCO3 - ATPase, Mg ++ , HCO3 - ATPase were observed. Two basic hypotheses were tested viz., (a) the sublethal in vivo exposure of TCDD evokes a dose and duration dependent effects on the membrane bound ATPases of the renal cells of mice and (b) TCDD possibly has a direct effect on the membrane bound ATPase system. Two groups were exposed to two sublethal doses (0.004 mg/kg bw/d, 0.04 mg/kg bw/d) of TCDD by a daily oral administration for 2, 4 and 6 days. A separate control group received corn oil for same exposure duration. The results indicated predominant exposure duration dependent alterations in membrane bound ATPases. In conclusion, the results suggested that the membrane bound ATPases were indeed influenced by the TCDD exposure. However, the effects were possibly indirect, by complex chains of reactions exhibited by the cells when subjected to the toxic stress. Keywords: ATPases, Dose & Duration dependent toxicity, Kidney, mice, TCDD

Low Dose Tcdd Affects Membrane Bound Ion Dependent Atpases in Mice Liver

Present communication reports in vivo dose and duration dependent effects of a dioxin (2,3,7,8 TCDD) on few membrane bound ion dependent ATPases of mice hepatocytes. Two hypotheses were tested in this study. Separate groups of mice were exposed to two very low sublethal doses (0.004 mg/kg bw, 0.04 mg/kg bw) of TCDD by daily oral administration for 2, 4 and 6 days. Separate control groups were also maintained which received only corn oil, the vehicle. The results indicated a significant exposure duration dependent alterations in the membrane ATPases. No clear dose dependent effects were observed. The results suggested that the observed alteration in the enzyme activity was possibly due to the oxidative stress generated by TCDD on the membrane-bound ion-dependent ATPases. The results also indicated that the membrane bound hydrophilic ATPases were indeed influenced by the hydrophobic TCDD. However, the effects were possibly indirect through complex chain of reactions exhibited by the cells under in vivo conditions. ROS was suspected to have played an important role in the alterations of membrane transport systems and permeability which caused cellular injury, and thereby exhibiting exposure duration dependent effects.

Growth of Pectoral Muscle Fibres in Relation To Somatic Growth in Some Marine Fishes

In the present communication, growth dynamics of pectoral muscle fibres of four marine fishes are described in relation to their somatic growth and the results are comparedwith our earlier findings on Caranx malabaricus. Over the entire investigated size range, the growth of red fibres was principally by hyperplasia. In pink fibres, cessation of hyperplasia was found in three of the five investigated species, whereafter further growth was only by hypertrophy of existing fibres. In white fibres, hypertrophy is a more important mode of growth than in other muscle fibre types. This was apparent from a smaller fish size at which addition of new fibres ceased or from a steeper slope of the relationship between muscle fibre diameter and fish fork length for most of the investigated fishes. However, Boleophthalmus dentatus seems to be an exception. The observed fibre growth dynamics of these fishes are similar to those of myotomal and caudal muscles.

Identification of a group of cryptic marine limpet species, Cellana karachiensis (Mollusca: Patellogastropoda) off Veraval coast, India, using mtDNA COI sequencing

Abstract Present communication reports the phylogenetic relationship between three groups of a marine limpet having different color banding patterns using COI sequencing. Samples were sequenced for mtDNA COI gene using universal primer. Comparative BLAST revealed that all three types were around 99.59% identical with Cellana karachiensis, first record of this species from Indian coasts. Apart from the morphological variations, the mtDNA COI gene analysis revealed around 1% nucleotide variations between these three types. The observed dissimilarity in COI sequences was possibly too little to consider these types as three different species. The derivation of amino acid positions indicated that these types could possibly be a complex of three cryptic species of C. karachiensis. The study proposes that the Oman and Indian populations of C. karachiensis might have derived by allopatric speciation due to geographical isolation. The group of these three cryptic species, sharing same habitat between themselves, possibly showed sympatric speciation.

Low Doses of a PCB (Aroclor 1254) Affect the Body Weight by Decreasing the Activity of Glucose-6-Phosphatase in the Liver and Kidney Cells of Mice

In this communication, toxicity of very low doses of Aroclor 1254, the most potent PCB, was evaluated in respect to gross body weight and glucose-6-phosphatase (G6Pase) activity in liver and kidney cells of mice. The study was designed to test three hypotheses. Groups of adult male Swiss albino mice were subjected to two very low and environmentally available doses (0.1 & 1 mg/kg bw/d) of Aroclor 1254 exposed for three durations (4, 8 & 12 d). The toxicant was administered orally and the specific activity of glucose-6- phosphatase was estimated from the liver and kidney cells of mice. The doses selected were significantly lower than the lethal dose but comparable to possible human exposure from different sources. The results revealed significant dose and exposure duration dependent effects of Aroclor on total body weight and the activity of glucose-6-phosphatase in liver and kidney cells of mice. The observed results suggested that all three hypotheses were true. It may be possible that the activation of AhR mediates the suppression of body weight and the activity of glucose-6-phosphatase, which suggested a role for these pollutants as disruptors of energy metabolism.

Probing the phylogenetic relationships of a few newly recorded intertidal zoanthids of Gujarat coast (India) with mtDNA COI sequences

Abstract The present study reports the phylogenetic relationship of six zoanthid species belonging to three genera, Isaurus, Palythoa, and Zoanthus identified using systematic computational analysis of mtDNA gene sequences. All six species are first recorded from the coasts of Kathiawar Peninsula, India. Genus: Isaurus is represented by Isaurus tuberculatus, genus Zoanthus is represented by Zoanthus kuroshio and Zoanthus sansibaricus, while genus Palythoa is represented by Palythoa tuberculosa, P. sp. JVK-2006 and Palythoa heliodiscus. Results of the present study revealed that among the various species observed along the coastline, a minimum of 99% sequence divergence and a maximum of 96% sequence divergence were seen. An interspecific divergence of 1–4% and negligible intraspecific divergence was observed. These results not only highlighted the efficiency of the COI gene region in species identification but also demonstrated the genetic variability of zoanthids along the Saurashtra coastline of the west coast of India.