Mitali Ray

Toxicity of sodium arsenite in the gill of an economically important mollusc of India.

Toxicity of arsenic was investigated in the gill of Lamellidens marginalis by exposing the animals to sublethal concentrations of sodium arsenite for a maximum period of 30 days in controlled laboratory conditions. Arsenite exposure inhibited the activities of acid phosphatase (ACP), alkaline phosphatase (ALP), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and acetylcholinesterase (AChE) in a dose and time dependent manner. Depletion in cytotoxic molecule like nitric oxide (NO) and suppression of phenoloxidase (PO) activity suggests an immune compromise in the animal. Inhibition in the activities of glutathione-s-transferase (GST) and catalase (CAT) in the species indicate impairment of its vital detoxification process and elevated oxidative stress respectively. Histopathology of the gill indicates arsenite induced damage of the organ leading to its possible dysfunction. The toxic exposure ravaged the structure and impaired the functions of the gill of the animal which might restrict its proper gaseous exchange, filter feeding and elicitation of immune responses against pathogens.

A comparative analyses of morphological variations, phagocytosis and generation of cytotoxic agents in flow cytometrically isolated hemocytes of Indian molluscs

A comparative analyses of hemocytes of molluscs, Pila globosa (Gastropoda: Prosobranchia), Bellamya bengalensis (Gastropoda: Prosobranchia) and Lamellidens marginalis (Bivalvia: Eulamellibranchiata) were carried out for morphotype and subpopulation identification, analyses of phagocytosis and generation of cytotoxic agents. Flow cytometry and microscopic analyses of hemocytes revealed the existence of agranulocytes (blast like cells, round hyalinocytes and spindle hyalinocytes), semigranulocytes (semigranular asterocytes and round semigranulocytes) and granulocytes (round granulocytes, spindle granulocytes and granular asterocytes) as three morphotypes. In P. globosa, granulocytes and semigranulocytes and in B. bengalensis granulocytes and agranulocytes are the chief phagocytes and major producers of superoxide anion and nitric oxide. In L. marginalis, granulocytes were identified as principal phagocytes with prominent activity of superoxide anion and nitric oxide. Highest activity of phenoloxidase was recorded in the agranulocytes of P. globosa with moderate activities among other morphotypes of all three species. Differential result may be due to species specific response, non-identical habitat preference and related adaptation of the species to their different ecological niches.

Phagocytic efficiency and cytotoxic responses of Indian freshwater sponge (Eunapius carteri) cells isolated by density gradient centrifugation and flow cytometry: a morphofunctional analysis.

The freshwater sponge Eunapius carteri (Porifera: Demospongiae: Spongillidae), a resident of Indian freshwater ecosystems, has pharmaceutical and ecological potential, but there is inadequate information on its cellular spectrum and cell-mediated immune responses. Microscopical analysis revealed the existence of eight distinct cellular variants, i.e. blast-like cells, choanocytes, small amoebocytes, granular cells, pinacocytes, large amoebocytes, archaeocytes and sclerocytes. The cells were isolated by density gradient centrifugation and flow cytometry and used for a morphofunctional analysis. We investigated the phagocytic efficiency of E. carteri cells under the challenge of yeast particles in vitro and spectrophotometrically quantified the generation of cytotoxic molecules (superoxide anions and nitric oxide) in different isolated cellular fractions. The two cell separating technologies did not yield any significant differences in the major findings on morphology, phagocytic response and generation of superoxide anions and nitric oxide. Archaeocytes, granular cells and large amoebocytes were identified as chief phagocytes with a high phagocytic potential as recorded by light microscopy. Archaeocytes were the principal generators of superoxide anions, whereas nitric oxide was recorded in the fractions rich in archaeocytes and large amoebocytes. The present investigation thus provides useful information regarding cellular variation, cytotoxic status and innate phagocytic response of the cells of E. carteri, a common but less studied sponge of India.

Cell to organ: physiological, immunotoxic and oxidative stress responses of Lamellidens marginalis to inorganic arsenite.

The emerging pollutants in diverse habitats have created a need for basic research towards profiling the structural and functional parameters ranging from cell to organs in a diversity of species, thus enabling realistic analyses of the risks imposed by the environmental stressors. In the present study, the circulating haemocytes and digestive gland of an edible bivalve mollusc from eastern India, Lamellidens marginalis, were investigated for morphological and functional attributes under the challenge of inorganic arsenite-an up-coming threat to the natural freshwater reserves of the Indo-Gangetic flood plains. The molluscs were exposed to three sublethal concentrations of sodium arsenite under controlled laboratory conditions for a maximum time span of thirty days. The toxic exposure caused significant alteration in the haemocytometric profile. It inhibited the activities of phosphatases, transaminases and acetylcholinesterase which are iconic for assessment of the physiological homoeostasis in the haemocytes and digestive tissue. At both cellular and tissue level, immune surveillance was compromised through inhibited generation of nitric oxide, phenoloxidase and superoxide anions. Moreover, exposure to sodium arsenite promoted xenometabolic and oxidative stress in both haemocytes and digestive gland by reducing the activity of glutathione S-transferase and catalase. It inflicted inflammatory damage and promoted neplasia in the digestive tissue as evident from the histopathological observations. The findings would be crucial to gauge the impending threats from inorganic arsenite exposure to the freshwater invertebrates. Further, it creates an avenue to speculate a new model for arsenic biomonitoring.

Evaluation of phagocytic activity and nitric oxide generation by molluscan haemocytes as biomarkers of inorganic arsenic exposure

The natural habitats of the freshwater bivalve Lamellidens marginalis face the risk of contamination by the toxic metalloid arsenic. Haemocyte-mediated non-self phagocytosis and generation of nitric oxide (NO) as reactive nitrogen intermediate were examined to establish the reliability of the parameters as biomarkers of sodium arsenite-induced stress on the animal at sublethal concentrations. The studies suggest imposition of a remarkable immune compromise/immune suppression on the animal by the natural contaminant. The animal expressed partial recovery in its phagocytic potential and NO generation over a period of 30 days. Quantitation of phagocytic efficiency and intrahaemocyte NO generation indicates the possibility of the parameters be accepted as cellular biomarkers to estimate and characterize the vulnerability of the freshwater organisms to sodium arsenite-induced stress.

Immunotoxicity of washing soda in a freshwater sponge of India.

The natural habitat of sponge, Eunapius carteri faces an ecotoxicological threat of contamination by washing soda, a common household cleaning agent of India. Washing soda is chemically known as sodium carbonate and is reported to be toxic to aquatic organisms. Domestic effluent, drain water and various human activities in ponds and lakes have been identified as the major routes of washing soda contamination of water. Phagocytosis and generation of cytotoxic molecules are important immunological responses offered by the cells of sponges against environmental toxins and pathogens. Present study involves estimation of phagocytic response and generation of cytotoxic molecules like superoxide anion, nitric oxide and phenoloxidase in E. carteri under the environmentally realistic concentrations of washing soda. Sodium carbonate exposure resulted in a significant decrease in the phagocytic response of sponge cells under 4, 8, 16 mg/l of the toxin for 96h and all experimental concentrations of the toxin for 192h. Washing soda exposure yielded an initial increase in the generation of the superoxide anion and nitric oxide followed by a significant decrease in generation of these cytotoxic agents. Sponge cell generated a high degree of phenoloxidase activity under the experimental exposure of 2, 4, 8, 16 mg/l of sodium carbonate for 96 and 192 h. Washing soda induced alteration of phagocytic and cytotoxic responses of E. carteri was indicative to an undesirable shift in their immune status leading to the possible crises of survival and propagation of sponges in their natural habitat.

Arsenic toxicity: A heart-breaking saga of a freshwater mollusc

The freshwater wetland systems of India is a complex habitat that supports a broad range of diverse species including molluscs, which play an important role in supplementing third world countries. In the arsenic affected flood plains of West Bengal, a huge amount of arsenic laden groundwater is raised for the purpose of irrigation. Agricultural runoffs and flood water movement during monsoon may cause accumulation of arsenic in the adjacent freshwater aquifers, the common habitat of Lamellidens marginalis (Mollusca; Bivalvia; Eulamellibranchiata), a filter feeder, sensitive to altered environmental conditions. To examine the nature of toxicity induced by inorganic arsenic on both the haemocytes and tissues of the invertebrate heart, the animals were exposed to five different sublethal concentrations of sodium arsenite for a maximum time span of 30 days in vitro. Significant differences were recorded in the total haemocyte count, biochemical and histopathological parameters of the heart of L. marginalis under the arsenic induced stress. Our observations indicate the development of profound haematopoietic and cardiac stress under the sublethal inorganic arsenite exposure and it also implies the nature of risk imposed on the freshwater aquatic ecosystem under potential arsenic contamination.

Shift in aggregation, ROS generation, antioxidative defense, lysozyme and acetylcholinesterase activities in the cells of an Indian freshwater sponge exposed to washing soda (sodium carbonate).

Washing soda, chemically identified as anhydrous sodium carbonate, is a popular cleaning agent among the rural and urban populations of India which often contaminates the freshwater ponds and lakes, the natural habitat of sponge Eunapius carteri. Present investigation deals with estimation of cellular aggregation, generation of ROS and activities of antioxidant enzymes, lysozyme and acetylcholinesterase in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Prolonged treatment of washing soda inhibited the degree of cellular aggregation. Experimental exposure of 8 and 16mg/l of sodium carbonate for 48h elevated the physiological level of reactive oxygen species (ROS) generation in the agranulocytes, semigranulocytes and granulocytes of E. carteri, whereas, treatment of 192h inhibited the ROS generation in three cellular morphotypes. Activities of superoxide dismutase, catalase and glutathione-S-transferase were recorded to be inhibited under prolonged exposure of washing soda. Washing soda mediated inhibition of ROS generation and depletion in the activities of antioxidant enzymes were indicative to an undesirable shift in cytotoxic status and antioxidative defense in E. carteri. Inhibition in the activity of lysozyme under the treatment of sodium carbonate was suggestive to a severe impairment of the innate immunological efficiency of E. carteri distributed in the washing soda contaminated habitat. Washing soda mediated inhibition in the activity of acetylcholinesterase indicated its neurotoxicity in E. carteri. Washing soda, a reported environmental contaminant, affected adversely the immunophysiological status of E. carteri with reference to cellular aggregation, oxidative stress, antioxidative defense, lysozyme and acetylcholinesterase activity.

Immunotoxicological Threats of Pollutants in Aquatic Invertebrates

Immunology deals with the physiological activity of organisms to defend against pathogen and toxin invasion. Invertebrates residing in aquatic ecosystems often face toxicological threat arises from habitat pollution. The aquatic habitat of invertebrates is in the precarious risk of pollution caused by diverse groups of environmental toxins. Immunotoxins have been considered as a special group of pollutants capable of affecting the immunological profile of organisms. Invertebrates residing in water bear ecological, economical, medicinal, industrial, nutritional and biotechnological significance. Global aquatic bioresource is largely composed of invertebrates belonging to multiple Phyla. These organisms, including insects, snails, clams, mussels, crabs and sponges, are physiologically dependent on innate immunological response for defense against pathogen and environmental contaminants. External physicochemical barriers of invertebrates act as primary line of defen against toxin entry. Principal barriers have been identified as shell, tunic, test, carapace, mucus, etc., in diverse species. Toxin-induced morphological damage of specialized immunocytes of invertebrates has been reported. Toxin-induced shift in density, surface adhesion efficacy and aggregation of blood cells or haemocytes have been identified as major xenobiotic stress in invertebrates. Various environmental toxins are capable of initiating alteration in the innate phagocytic response and cytotoxicity of blood cells. Lysosomes of invertebrate haemocytes are functionally involved in intracellular destruction of environmental pathogens. Toxins like arsenic, pyrethroid pesticides, azadirachtin and washing soda were reported to increase the relative fragility of

Morphological alteration, lysosomal membrane fragility and apoptosis of the cells of Indian freshwater sponge exposed to washing soda (sodium carbonate)

Washing soda is chemically known as sodium carbonate and is a component of laundry detergent. Domestic effluent, drain water and various anthropogenic activities have been identified as major routes of sodium carbonate contamination of the freshwater ecosystem. The freshwater sponge, Eunapius carteri, bears ecological and evolutionary significance and is considered as a bioresource in aquatic ecosystems. The present study involves estimation of morphological damage, lysosomal membrane integrity, activity of phosphatases and apoptosis in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Exposure to washing soda resulted in severe morphological alterations and damages in cells of E. carteri. Fragility and destabilization of lysosomal membranes of E. carteri under the sublethal exposure was indicative to toxin induced physiological stress in sponge. Prolonged exposure to sodium carbonate resulted a reduction in the activity of acid and alkaline phosphatases in the cells of E. carteri. Experimental concentration of 8 mg/l of washing soda for 192 h yielded an increase in the physiological level of cellular apoptosis among the semigranulocytes and granulocytes of E. carteri, which was suggestive to possible shift in apoptosis mediated immunoprotection. The results were indicative of an undesirable shift in the immune status of sponge. Contamination of the freshwater aquifers by washing soda thus poses an alarming ecotoxicological threat to sponges.