Samar Gourav Pati

The journal retracts the article titled, “Allantoin and Tissue Specific Redox Regulation in Mud Crab Scylla serrata under Varied Natural Water Physico-Chemical Parameters”

Effects of varied sediment and physico-chemical properties of water on allantoin content in tissues of Scylla serrata and its role in antioxidant homeostasis were investigated. Tissues of crabs were sampled from different coastal natural habitats of S. serrata of India during summer, winter, and rainy seasons and were analyzed to detect the variation in allantoin content and lipid peroxidation (LPx) and oxidative stress (OS) neutralizing antioxidant factors. High allantoin content in hepatopancreas over muscle tissue was observed in all seasons and sampling sites. The correlation coefficient values between allantoin and environmental factors, i.e., temperature, pH, salinity, organic carbon, Mg, and Ca, strongly support the stress-induced allantoin variation level in tissues. The level of allantoin had a negative correlation with levels of ROS, which was probably due to the upregulation of the activity of major antioxidant enzymes and assisting enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), and biotransforming enzyme glutathione -s- transferases (GST). A significant seasonal variation in the level of allantoin was correlated with the activity of including superoxide dismutase, catalase, GPx, GR, and GST, which was clearly noticed as a function of abiotic factors. Additionally, the level of allantoin did not correlate with small antioxidant molecules, such as ascorbic acid and reduced glutathione. Discriminant function analysis revealed that the level of allantoin and CAT and GR activities were the major contributing factors for the clear discrimination of groups. Therefore, allantoin can be considered as a significant factor for the seasonal modulation of OS physiology in mud crab Scylla serrata.

The oxidative stress (OS) condition and antioxidant level as a function of pH, few major elements, temperature, turbidity, organic carbon, sediment, and water salinity are vital to understanding the redox homeostasis of inhabiting animals. These parameters are also used to monitor environmental health. A spatiotemporal redox antioxidant system, followed by discriminant function analysis about the aforementioned abiotic factors, was investigated in the muscle, gill, and hepatopancreas of the mud crab, Scylla serrata, sampled from the Indian coastal belt along the Bay of Bengal (Tamil Nadu and Odisha) and the Arabian Sea (Gujarat) as a measure of environmental health assessment. Results revealed that the redox homeostasis of mud crabs significantly varied with seasonal fluctuations of abiotic factors and sediment chemistry. The level of superoxide dismutase and the non-protein-SH group were negatively correlated, whereas other antioxidant molecules with lipid peroxidation levels were positively correlated with abiotic factors. Only the activities of glutathione peroxidase and glutathione reductase were strongly correlated with all the abiotic factors. The hepatopancreas was found to be the most susceptible organ to OS. The lipid peroxidation level was 20–25 times higher in hepatopancreatic tissue than that in other tissues. The antioxidant level was elevated to 200% during the summer compared to the rainy season. Thus, the results of redox homeostasis in S. serrata may be useful for monitoring the ecotoxic effects of estuarine and marine environments and managing the inhabiting species.

The water of the mangrove ecosystem and surrounding coastal areas are gradually shrinking due to the intense destruction. Therefore, the effects of the physicochemical properties of the habitat water on the in-habitant species must be studied. Scylla sp. is involved in the food chain and bioturbation structure formation in mangrove forests. Five major electronic databases, such as PubMed, Scopus, Web of Science, AGRICOLA, and Google Scholar, were systematically searched to review the cause and effects of influencing abiotic factors, mainly physicochemical properties of habitat water, including water pollution on Scylla sp. Responses of mud crabs at biochemical, molecular, physiological, growth, reproduction, and production level were independently reviewed or in relation to physicochemical properties of habitat water, pathogens, heavy metals, and harmful chemicals present in their habitat water. Review results suggest that these crabs are mostly under threats of overfishing, varied physicochemical properties of habitat water, pathogens, heavy metals, and chemical toxicants in water, etc. At low temperatures, the expression of calreticulin and heat shock protein-70 mRNA expression is elevated. Like melatonin, the hormone serotonin in mud crabs controls ecdysteroids and methyl farnesoate at 24 °C, 26 ppt salinity, and pH 7.2 of habitat water, facilitating their reproduction physiology. Xenobiotics in habitat water induce toxicity and oxidative stress in mud crabs. These crabs are prone to infection by white spot and rust spot diseases during the winter and spring seasons with varied water temperatures of 10–30 °C. However, elevated (65%) weight gain with higher molting at the juvenile stage can be achieved if crabs are cultured in water and kept in the dark. Their larvae grow better at 30 ± 2 °C with salinity 35 ppt and 12 hL/12 hD day length. So, monitoring habitat water quality is important for crab culture.

Salinity is a decisive abiotic factor that modulates the physiology of aquatic organisms. Salinity itself is modulated by various factors—most notably by anthropogenic factors. In coastal regions, increasing salinity is observed mostly due to the elevated rate of evaporation under high temperatures, especially under global warming. In addition, many other anthropogenic factors, climatic factors, chemicals, etc., also contribute to the changes in salinity in coastal water. Some of these include rainfall, regional warming, precipitation, moisture, thermohaline circulation, gaseous pollutants, dissolved chemicals, wind flow, and biocrusts. Salinity has been found to regulate the osmotic balance and, thus, can directly or indirectly influence the biomarkers of oxidative stress (OS) in aquatic organisms. Imbalances in OS potentially affect the growth, production, and reproduction of organisms; therefore, they are being studied in organisms of economic or aquacultural importance. Salinity-modulated OS and redox regulation as a function of phylum are covered in this review. The literature from 1960 to 2021 indicates that the altered OS physiology under changing salinity or in combination with other (anthropogenic) factors is species-specific, even within a particular phylum. Thus, knowing the response mechanisms of such organisms to salinity may be useful for the management of specific aquatic animals or their habitats.

The semi-sessile, ectothermic, amphibious mollusc Pila globosa receives less attention for studying its environmental aspects. Its ecological role, ecotoxic and physiological responses to environmental factors including pollution and during dormant periods such as hibernation and estivation to understand key information about many cellular metabolic events need to be revealed. We reviewed the ecotoxic and physiological responses of P. globosa to various abiotic and biotic stressors such as heavy metals, organophosphorous, carbamate and butachlor in relation its adaptation to energy expenditure, fat metabolism in the dormant period, desiccation, etc. The responses analysed in terms of oxidative stress, respiratory and antioxidant enzymes, carbohydrate metabolism and activities of neurotransmitter enzymes such as acetylcholinesterase to better understand the connection between environmental factors and metabolic events in P. globosa. Articles published in the English language from 1952 to July of 2022 in PubMed, Google search engine and AGRICOLA that describes any of the above-mentioned search terms in P. globosa were included in the review article. Articles not containing any of the above terms were excluded. The 41 results were found in PubMed and 10 results from AGRICOLA and about 80 filtered articles from Google, totaling about 80 articles published until July 2022 were included in this review. The varied enzymatic activities observed in this organism under the exposure to various chemicals imply their possible use as biomarkers of eco-toxicological studies in freshwater and grassland ecosystems, for example, alleviated body carbohydrate and protein contents are up to 32% and 37% during aestivation and hibernation, respectively. Similarly, activities of enzymes such as adenosine monophosphate deaminase, adenosine deaminase, succinic dehydrogenase, cytochrome-c-oxidase, and glutamate dehydrogenase are downregulated by 75.5%, 62.6%, 54%, 59%, and 62%, respectively, during above inactive periods. Acetylcholinesterase enzyme is found to be the most susceptible enzyme to be downregulated by 225%, 130%, 64%, 198%, 96.08% in this snail under exposure to environmental pollutants such as phorate (30 mg/L), formothion (37.5 mg/L), trichlorfon (2.5 mg/L), aldicarb (120 mg/L) and butachlor (100 µ moles), respectively. In conclusion, P. globosa can serve as a reliable ectothermic model for comparative ecotoxicological studies in grassland and freshwater environmental monitoring.

Studies on oxidative stress physiology on molluscs to monitor the aquatic environment, influenced by pollutants and stressors are very limited in general and in Indian apple snails, P. globosa in particular. The main focus of the present study was to establish the baseline data on a redox regulatory system in P. globosa sampled across the Indian subcontinent. Snails were sampled from different zones of India in three seasons (rainy, summer and winter) and the redox regulatory system (levels of antioxidant enzyme activities and small redox regulatory molecules) and oxidative stress indicator (lipid peroxidation) were analyzed. The observed elevated lipid peroxidation level in the summer season accompanied with elevated pH, salinity and temperature indicates induction of stress. In the summer season, the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) enzymes were augmented, whereas the level of the free -SH group and the activities of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were found to be increased. Similarly, correlation analysis between the antioxidant system and aquatic parameters revealed that SOD, CAT and GR were influenced by pH as well as salinity, whereas CAT was strongly correlated with temperature. Collectively, our data indicate the use of P. globosa as a model organism to monitor and access the freshwater environment by determining the redox regulatory status of this animal.

Studies on the synergetic effects of soil and water parameters on Oxidative Stress (OS) physiology systems of the edible mud crab Scylla serrata sampled from different parts of East India are unknown. This study aimed to evaluate the effects of soil Ca, Mg, and organic carbon load and water physicochemical stressors induced spatio-temporal variation of tissue-specific OS and antioxidant parameters in S. serrata along the Bay of Bengal in Odisha. Spectrophotometric or Fourier-transform infrared spectroscopy methods were employed to measure the OS physiology and physicochemical parameters. Pedological and physicochemical factors of water were varied significantly in summer (38–42°C), rainy (25–35°C), and winter (12–20°C) seasons. Activities of antioxidant enzymes (AE) such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and the level of lipid peroxidation (LPx) were found to be higher in hepatopancreas as compared to other tissues irrespective of seasonal variation. Considering the impact of dry seasons, an average of 13.23% enhanced activities of AE were noticed in different tissues of S. serrata in response to temperature, salinity, organic carbon, Mg, and Ca load of sampling sites. However, about 11.26% decrease in the activities of AEs, including GR and GST in most of the tissues were recorded, along with a 21% alleviated level of LPx observed in the rainy season compared to other seasons. Among three coastal zones of the Bay of Bengal, the AEs in crabs sampled from Chandipur were elevated by 5.43% in winter, whereas a 7.05% enhanced level of LPx was found in summer compared to crabs sampled from Chilika and Jagatsinghpur. Overall, the levels of LPx, total antioxidant, and activities of AEs (CAT, GST, GPx, and GR) have shown a positive correlation, whereas ascorbic acid and GSH negatively correlate with habitat water pH, temperature, and salinity of soil and water. The results can be used for ecotoxic and environmental biomonitoring purposes using crabs as model organisms across tropical coastal regions.

Information on the oxidative stress physiology parameters (OSPP) in general and as a function of the fluctuation of Mg, Ca and organic carbon present in soil and aquatic physico-chemical factors such as pH, temperature and salinity in particular are scanty in the amphibious snail Pila globosa. A spatio-temporal analysis of redox metabolism (as OSPP) followed by discriminant function analysis of the obtained data were performed in P. globosa sampled from the east-coasts of Odisha state, India (mostly along the Bay of Bengal) for environmental health assessment purposes. Results revealed that the OSPP are susceptible to seasonal synergistic variation of soil and physico-chemical factors. Overall, lipid peroxidation, total antioxidant capacity, activities of catalase, glutathione reductase had positive correlation whereas ascorbic acid, the reduced glutathione and the activity of superoxide dismutase had non-significant correlation with the soil Mg, Ca, organic carbon, and pH, temperature and salinity of water. In the summer season, the snails had a marked 51.83% and 26.41% higher lipid peroxidation level and total antioxidative activity as compared to the other seasons. Spatial variation of OSPP indicates that snails residing away from the Bay of Bengal coast had at least 4.4% lower antioxidant level in winter and 30% higher lipid peroxide levels in summer as compared to the rest of the sampling sites. Results on OSPP in P. globosa may be useful for monitoring the ecotoxic effects of environment using molluscs in general and P. globosa in particular.