Estuarine Crab Scylla Serrata Research Articles

Vicissitudes of oxidative stress biomarkers in the estuarine crab Scylla serrata with reference to dry and wet weather conditions in Ennore estuary, Tamil Nadu, India

The primary objective of this study was to understand the impact of monsoon and summer seasons on the Polychlorinated Biphenyls (PCB's) and petroleum hydrocarbon compounds (PHC's) load in Ennore estuary and how the physiological response of estuarine Scylla serrata inhabiting in this estuary changed with reference to antioxidant defense. Seasonal levels of PCB's and PHC's were assessed in the water along with their bioaccumulation in gills, hemolymph, hepatopancreas and ovary of S. serrata. Concentration of PCB's and PHC's in water and their bioaccumulation was found to be higher in summer season when compared to monsoon season. Enzymic antioxidant assays [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), glutathione-S-transferase (GST)]; non-enzymic antioxidant assays [glutathione (GSH), vitamin C, vitamin E] and macromolecular alterations [membrane lipid peroxidation (LPO), and DNA Damage (strand breaks)] were assessed in the gills, hemolymph and hepatopancreas of S. serrata. There was a significant (p<0.05) upregulation in lipid peroxidation activity and DNA damage activity collected during the summer season when compared to the pre- and post-monsoon seasons. On the contrary, the enzymic and non-enzymic antioxidants exhibited significant (p<0.05) down regulation in the gills, hemolymph, hepatopancreas and ovary of S. serrata. Oxidative stress biomarkers represented a significant (p<0.05) maximum in gills when compared to hemolymph and hepatopancreas of S. serrata. Present study provided scientific evidences of how the antioxidant defense status of S. serrata responded to PCB's and PAH's stress with reference to seasonal vicissitudes, which indirectly represented the environmental health conditions of the estuary.

Tn/T Specific Agglutinin from Estuarine Crab Scylla Serrata with Potent Mitogenic Activity on Mouse Splenocytes and Antiproliferative Effect on Hepatocellular Carcinoma (HepG2) Cell

A lectin was purified from the hemolymph of esturarine crab Scylla serrata by successive 40% (NH4)2SO4 precipitation, affinity chromatography on asialo fetuin- Sepharose column, Resource Q anion-exchanger in FPLC system and designated as scyllin-2. Scyllin-2 was a homogeneous monomeric protein of molecular mass 75 kD judged by SDS-PAGE and confirmed by ESI-MS-Q-ToF. Its activity was Ca+2 dependent being maximum at pH 7.5 and at 20 °C. N-terminal sequence of scyllin-2 showed close resemblance to peanut lectin and histidine kinase A. It agglutinated human O, A, B and AB blood group erythrocytes equally well and showed maxi- mum inhibition with α-Gal by hapten-inhibition study. The detailed carbohydrate specificity of scyllin-2 was determined at the macro-molecular level based on the Gal/GalNAc structural units in the mammalian glycoproteins by enzyme-linked lectinosorbent (ELLSA) and inhibition assays. It revealed that scyllin-2 binds specifically to tumor-associated carbohydrate antigens GalNAcα1→Ser/Thr (Tn) and Galβ1→3GalNAcα1→Ser/Thr (Tα). It showed very weak binding with Galβ1→3/4GlcNAc (I/II) glycotopes on glycoproteins and T/Tn covered by sialic acid. Multivalancy of Tn/Tα containing glycoproteins tested resulted in higher binding of 102–104 order than the respective Gal and GalNAc monomer. Scyllin-2 stimulated proliferation of mouse splenocytes. Analysis of expression of receptors for scyllin-2 on HepG2 by flow cytometry showed the binding of FITC-scyllin-2 to HepG2 was 86.51%, which was nearly comparable to Artocarpus lakoocha agglutinin (ALA) (66.41%), another Tn/Tα specific lectin indicating that the glycan structure on HepG2 cell surface shows prevalence of Tn/Tα units. It inhibited proliferation of HepG2 cells (61 µg/ml). The inhibitory effect was comparable to ALA (80 µg/ml). Thus, we have characterized a Tn/T specific invertebrate lectin with biological significance.

RETRACTED: Fluctuations of certain biochemical constituents and markers enzymes as a consequence of monocrotophos toxicity in the edible freshwater fish, Channa punctatus

This article has been removed at the request of the Editor-in-Chief. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). Reason: this article has been retracted at the request of the Editor-in-Chief as the authors have plagiarized part of a paper that has previously been published in the journal Ecotoxicol. Environm. Safety , Volume 63, Issue 1, January 2006, pages 141-147; "Fluctuations of biochemical constituents and marker enzymes as a consequence of naphthalene toxicity in the edible estuarine crab Scylla serrata" by K. Vijayavel and M.P. Balasubramanian.

DNA damage and cell necrosis induced by naphthalene due to the modulation of biotransformation enzymes in an estuarine crab Scylla serrata

The sublethal effect of naphthalene (2.5, 5, and 10 mg L(-1)) was studied in an estuarine crab Scylla serrata with reference to macromolecular changes. Biotransformation enzymes such as cytochrome P450, cytochrome b(5), NADPH cytochrome P450 reductase, aryl hydrocarbon hydroxylase, glutathione-S-transferase, and UDP-glucuronyl transferase were elevated in the hepatopancreas of naphthalene-exposed crabs in comparison with control. Remarkable amount of DNA damage and cell necrosis was observed in hepatopancreas, hemolymph, and ovary of the crabs exposed to naphthalene, when compared with control. For all the parameters studied, a concentration-dependent gradient of the changes was observed. The expression of DNA damage and cell necrosis suggests an increased production of oxidants during naphthalene metabolism.

Reproductive dysfunction induced by naphthalene in an estuarine crab Scylla serrata with reference to vitellogenesis

Biomarkers are useful tools for understanding complex interactions that elicit organisms response to environmental pollutants and their sublethal effects on organisms health. Effect of naphthalene on vitellogenin (VTG) and vitellin (VTN) were assessed in hepatopancreas, haemolymph and ovary of an estuarine crab Scylla serrata with reference to vitellogenic phases. In addition, the gonadosomatic index (GSI) was also assessed. Significant reductions in VTG and VTN contents were observed in hepatopancreas, haemolymph (VTG) and ovary (VTN). The GSI exhibited a decreasing trend in crabs exposed to naphthalene irrespective of the vitellogenic phases. We attempted to use the alterations in vitellogenic proteins and GSI as biomarkers of reproductive disturbances occurred in the crab due to naphthalene stress.

Methionine-enkephalin induces hyperglycemia through eyestalk hormones in the estuarine crab Scylla serrata.

The hypothesis is tested that methionine-enkephalin, a hormone produced in and released from eyestalk of crustaceans, produces hyperglycemia indirectly by stimulating the release of hyperglycemic hormone from the eyestalks. Injection of methionine-enkephalin leads to hyperglycemia and hyperglucosemia in the estuarine crab Scylla serrata in a dose-dependent manner. Decreases in total carbohydrate (TCHO) and glycogen levels of hepatopancreas and muscle with an increase in phosphorylase activity were also observed in intact crabs after methionine-enkephalin injection. Eyestalk ablation depressed hemolymph glucose (19%) and TCHO levels (22%), with an elevation of levels of TCHO and glycogen of hepatopancreas and muscle. Tissue phosphorylase activity decreased significantly during bilateral eyestalk ablation. Administration of methionine-enkephalin into eyestalkless crabs caused no significant alterations in these parameters when compared to eyestalk ablated crabs. These results support the hypothesis that methionine-enkephalin produces hyperglycemia in crustaceans by triggering release of hyperglycemic hormone from the eyestalks.

In vivo binding of exogenous copper to haemolymph fractions of estuarine crab Scylla serrata (Forskal)

In vivo binding of exogenous Cu to different haemolymph fractions (plasma, haemocyanin, clarified plasma and haemocytes) was quantitatively determined in specimens of the estuarine crab Scylla serrata (Forskal) injected with Cu as cupric chloride. As a prerequisite to this study, a suitable amount of Cu for injection was empirically selected by injecting various amounts of Cu (5.0, 7.5, 10.0, 12.5 and 15.0 μM; injection volume: 0.2, 0.3, 0.4, 0.5 and 0.6 ml, respectively) into the haemocoel of crabs and monitoring the consequent changes in haemolymph-Cu level at different time intervals post-injection. Based on the amount of injected Cu present in circulation as well as the reaching of an apparent asymptote of the haemolymph-Cu level after injection, an injection dose of 10 μM was found to be suitable to investigate in vivo binding of exogenous Cu to different haemolymph fractions. In the haemolymph of uninjected crabs, no free Cu is detectable, 86% of the total haemolymph Cu is found in association with plasma proteins and 13% is associated with haemocytes (haemocyte lysate supernatant). Analysis of protein in haemocyanin fraction isolated from plasma revealed that 83% of the protein in plasma is haemocyanin. When the crabs were injected with 10 μM Cu, no free Cu was detectable in any of the haemolymph fractions tested at any time post-injection, the first haemolymph sample was analysed at 30 min post-injection. At 2 h post-injection, the Cu concentration in haemocyanin and haemocyte-lysate supernatant increased significantly and accounted for 63 and 20% of the total injected Cu, respectively. These observations demonstrate that haemocyanin and haemocytes play a significant role in binding exogenous Cu. The Cu level in these fractions decreased thereafter and reached almost the pre-injection level within 4 h post-injection. Concomitantly at this hour of post-injection, the protein level in haemocyanin and haemocytes decreased significantly. These observations clearly indicate the disappearance of excess Cu from circulation along with the carrier proteins and suggest a probable role of haemocyanin and haemocytes in transport of exogenous heavy metals.

Copper toxicity in the crab, Scylla serrata, copper levels in tissues and regulation after exposure to a copper-rich medium.

In the decapod crustaceans copper is distributed in various tissues. In these animals the tissue copper generally exists in four forms; ionic, bound to proteins, lipids and membrane. In the estuarine crab Scylla serrata, the haemolymph copper exists only in association with proteins, whereas in the hepatopancreas it exists in all the four forms and in gills it exists in all the forms except in combination with lipids. Although food is the major source of copper in decapod crustaceans evidence indicate that copper may be directly obtained from the environment. It was postulated earlier that in Scylla serrata the haemolymph and hepatopancreas may be involved in copper regulation. In the present work the authors have studied the nature and levels of copper in different tissues after exposing the crabs to copper-rich medium. The results indicate the relative importance of various tissues in accumulation an the possible mechanisms of regulation of the environmental copper. Besides, as a pre-requisite for studies of this kind, the toxic levels for different forms of copper were estimated since the form of toxicant is known to influence the toxicity to the decapod crustaceans.

Kinetic changes in flexor myosin ATPase of Scylla serrata adapted to different salinities

Kinetic properties such as the Michaelis-Menten constant and the activation energy of the flexor muscle myosin ATPase were investigated in the estuarine crab Scylla serrata. These properties varied at different salinities, but the extractability of the enzyme remained unaltered. The qualitative changes upon salinity adaptation are discussed with reference to estuarine conditions.