Aquatic invertebrates contribute significantly to environmental impact assessment of contaminants in aquatic ecosystems. Much effort has been made to identify viable and ecologically relevant invertebrate test organisms to meet rigorous... more
Aquatic invertebrates contribute significantly to environmental impact assessment of contaminants in aquatic ecosystems. Much effort has been made to identify viable and ecologically relevant invertebrate test organisms to meet rigorous regulatory requirements. Copepods, which are ecologically important and widely distributed in aquatic organisms, offer a huge opportunity as test organisms for aquatic toxicity testing. They have a major role not only in the transfer of energy in aquatic food chains, but also as a medium of transfer of aquatic pollutants across the tropic levels. In this regard, a supratidal and benthic harpacticoid copepod Tigriopus japonicus Mori (order Harpacticoida) has shown promising characteristics as a test organism in the field of ecotoxicology. Because there is a need to standardize a battery of test organisms from species in different phylogenetic and critical ecosystem positions, it is important to identify another unrelated planktonic species for wider a...
Research Interests: Genomics, Ecotoxicology, Aquatic Toxicology, Biomarkers, Biology, and 15 moreEcology, Environmental Monitoring, Medicine, Biological Sciences, Copepoda, Antioxidants, Aquatic Ecosystem, Environmental Sciences, Animals, Ecotoxicity, Organism, Behavioral Animal Models, CHEMICAL SCIENCES, Copepod, and Biological Assay
In environmental risk assessments (ERA), biomarkers have been widely used as an early warning signal of environmental contamination. However, biomarker responses have limitation due to its low relevance to adverse outcomes (e.g.,... more
In environmental risk assessments (ERA), biomarkers have been widely used as an early warning signal of environmental contamination. However, biomarker responses have limitation due to its low relevance to adverse outcomes (e.g., fluctuations in community structure, decreases in population size, and other similar ecobiologically relevant indicators of community structure and function). To mitigate these limitations, the concept of adverse outcome pathways (AOPs) was developed. An AOP is an analytical, sequentially progressive pathway that links a molecular initiating event (MIE) to an adverse outcome. Recently, AOPs have been recognized as a potential informational tool by which the implications of molecular biomarkers in ERA can be better understood. To demonstrate the utility of AOPs in biomarker-based ERA, here we discuss a series of three different biological repercussions caused by exposure to benzo(a)pyrene (BaP), silver nanoparticles (AgNPs), and selenium (Se). Using mainly a...
Research Interests: Earth Sciences, Biomarkers, Biology, Environmental Monitoring, Risk assessment, and 15 moreMedicine, Metal Nanoparticles, Aquatic Ecosystem, Environmental Sciences, Population, Animals, Fishes, CHEMICAL SCIENCES, Biomarker, Bioindicator, Aquatic organisms, Neoplasms, Pollutant, Risk Assessment, and Environmental Exposure
Expressed sequence tags (ESTs) and differentially expressed cDNAs from the self-fertilizing fish, Kryptolebias marmoratus were mined to develop alternative biomarkers for endocrine-disrupting chemicals (EDCs). 1,577 K. marmoratus cDNA... more
Expressed sequence tags (ESTs) and differentially expressed cDNAs from the self-fertilizing fish, Kryptolebias marmoratus were mined to develop alternative biomarkers for endocrine-disrupting chemicals (EDCs). 1,577 K. marmoratus cDNA clones were randomly sequenced from the 5'-end. These clones corresponded to 1,518 and 1,519 genes in medaka dbEST and zebrafish dbEST, respectively. Of the matched genes, 197 and 115 genes obtained Unigene IDs in medaka dbEST and zebrafish dbEST, respectively. Many of the annotated genes are potential biomarkers for environmental stresses. In a differential display reverse transcriptase-polymerase chain reaction (DD RT-PCR) study, 56 differential expressed genes were obtained from fish liver exposed to bisphenol A. Of these, 16 genes were identified after BLAST search to GenBank, and the annotated genes were mainly involved in catalytic activity and binding. The expression patterns of these 16 genes were validated by real-time RT-PCR of liver tiss...
Research Interests: Computational Biology, Biology, Environmental Monitoring, Medicine, Expressed Sequence Tags, and 15 moreEndocrine disruptors, Animals, Gene, Phenols, Fertilization, GenBank, Environmental Stress, Biological markers, Endocrine Disruptors, Killifishes, Differential Display, Biochemistry and cell biology, Gene Expression Regulation, Gene expression profiling, and reverse transcriptase polymerase chain reaction
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Research Interests: Chemistry, Biomarkers, Environmental Monitoring, Comparative Study, Aquatic Ecosystem, and 15 moreKidney, Liver, Animals, Glutathione, Catalase, Glutathione Peroxidase, Freshwater Fish, Enzyme, Gills, Biological markers, Dissolved Oxygen, Chemical Oxygen Demand, Gill, Glutathione Reductase, and Biochemical Oxygen Demand
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In recent years, there has been a decline in the wild populations of river pufferfish, Takifugu obscurus. Besides overexploitation for commercial purposes, environmental pollution is believed to have contributed to its decline. However,... more
In recent years, there has been a decline in the wild populations of river pufferfish, Takifugu obscurus. Besides overexploitation for commercial purposes, environmental pollution is believed to have contributed to its decline. However, almost no information exists about genes involved in metabolism of xenobiotics by this species. Nevertheless, there is interest in fugu fishes, since they possess the smallest genome among vertebrates. We cloned and characterized the full-length cDNA sequence of a cytochrome P450 1A (CYP1A) gene from T. obscurus. Phylogenic relationship of T. obscurus CYP1A was also compared to other fish species. The tissue distribution and time-dependant induction of CYP1A mRNA were studied by real-time PCR in T. obscurus exposed to an aryl hydrocarbon receptor (Ahr) agonist, beta-naphthoflavone (BNF). The greatest basal expression in livers of control as well as BNF-treated individuals. However, brain, gill, gonad, intestine, and kidney also expressed CYP1A. Muscles expressed the least CYP1A. The results of the time-course study revealed induction in brain and gills after 6h and at 12h in most tissues. Except for gills, all other organs retained induced expression of CYP1A mRNA up to 96h.
Research Interests: Biology, Environmental Pollution, Medicine, Multidisciplinary, real time PCR, and 14 morePhylogeny, Xenobiotic metabolism, Animals, Aryl Hydrocarbon Receptor, Molecular cloning, Time Dependent, Population Decline, Gill, Amino Acid Sequence, Base Sequence, Time Course, Full Length Movies, Molecular Sequence Data, and Tissue distribution
To evaluate the effect of pre‐ or posttreatment of selenium (6 μmol/kg b.w., single intraperitoneal injection) in mercury intoxication, rats were exposed to mercury (12 μmol/kg b.w., single intraperitoneal injection). Exposure to mercury... more
To evaluate the effect of pre‐ or posttreatment of selenium (6 μmol/kg b.w., single intraperitoneal injection) in mercury intoxication, rats were exposed to mercury (12 μmol/kg b.w., single intraperitoneal injection). Exposure to mercury resulted in induced oxidative stress in liver, kidney, and brain tissues. Marked changes in serum biochemical parameters together with alterations in histopathology and an induction in metallothionein‐I and metallothionein‐II mRNA expression in the liver and kidney were observed. Pretreatment with selenium to mercury‐exposed animals had protective effect on the liver, whereas posttreatment had partial protection on restoration of altered oxidative stress parameters. In the kidney, pretreatment with selenium showed partial protection on restoration of altered biochemical parameters, whereas no protection was observed in posttreatment. The pretreatment with selenium resulted in restoration of mercury‐induced metallothionein‐I and metallothionein‐II mR...
Research Interests: Chemistry, Oxidative Stress, Medicine, Kidney, Liver, and 15 moreMercury, Animals, Male, Glutathione, Catalase, Glutathione Peroxidase, Metallothionein, Biochemical, Lipid peroxidation, mRna expression levels, Rats, Biochemical and Molecular Toxicology, Gene Expression Regulation, Pharmacology and pharmaceutical sciences, and mRNA expression
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Cyclophosphamide (CP) is one of the most popular alkylating anticancer drugs in spite of its toxic side effects including immunotoxicity, hematotoxicity, mutagenicity and a host of others. The present study was undertaken to assess the... more
Cyclophosphamide (CP) is one of the most popular alkylating anticancer drugs in spite of its toxic side effects including immunotoxicity, hematotoxicity, mutagenicity and a host of others. The present study was undertaken to assess the protective effects of total aqueous extract of a medicinal plant, Indian gooseberry (Emblica officinalis Gaertn.) in mice treated with CP. These protective effects were studied on immunological parameters and kidney and liver antioxidants. Plant extract treatment at a dose of 100 mg/kg body weight per os (p.o.) for 10 days resulted in the modulation of these parameters in normal as well as CP (50 mg/kg)-treated animals. Plant extract in particular was very effective in reducing CP-induced suppression of humoral immunity. Plant extract treatment in normal animals modulated certain antioxidants of kidney and liver. In CP-exposed animals, plant pretreatment provided protection to antioxidants of kidney. Not only were the reduced glutathione levels signif...
Research Interests: Biology, Human, Antioxidants, Female, Animals, and 15 moreAntioxidant, Bone marrow, Human Experimentation, Antioxidant enzyme, Cancer Patient, Body Weight, Combination drug therapy, Emblica Officinalis, Aqueous Extract, Cyclophosphamide, Anticancer Drug, Humoral Immunity, Combination Therapy, Hypersensitivity Delayed, and Guinea pigs
The corticotropin-releasing hormone (CRH) plays a critical role in stress-response regulation in vertebrates. The activity of CRH depends on CRH-binding protein (CRH-BP). CRH-BP is considered to play a chaperoning role in stress. Limited... more
The corticotropin-releasing hormone (CRH) plays a critical role in stress-response regulation in vertebrates. The activity of CRH depends on CRH-binding protein (CRH-BP). CRH-BP is considered to play a chaperoning role in stress. Limited information mainly from the insects is available on the molecular structure and functions of invertebrate CRH and CRH-BP. We cloned and sequenced a CRH-BP gene from the intertidal copepod, Tigriopus japonicus which was expressed at all the stages of development. Molecular phylogenetic analysis showed that T. japonicus CRH-BP was closely related to CRH-BP of honeybee and other insects. The highest level of CRH-BP transcripts was expressed in adult males followed by nauplius stage 1. The expression of CRH-BP was upregulated when T. japonicus was subjected to temperature or salinity stress. This study demonstrates that CRH-BP in T. japonicus might play a role in stress-response. However, establishing such a role demands further studies on CRH-BP from other invertebrates and their expression under stress.
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Research Interests: Environmental Toxicology, Ecotoxicology, Biology, Medicine, Biological Sciences, and 15 moreCopepoda, Heavy metals, Environmental Sciences, Pesticides, Endocrine disruptors, Animals, Polychlorinated Biphenyls, Ecotoxicity, CHEMICAL SCIENCES, Phenols, Copepod, Pacific ocean, Endocrine Disruptors, Lethal Dose, and Acute Toxicity
The pyrethroid class of insecticides, including deltamethrin, are being used as substitutes for organochlorines and organophosphates in pest-control programs because of their low environmental persistence and toxicity. Ecotoxicological... more
The pyrethroid class of insecticides, including deltamethrin, are being used as substitutes for organochlorines and organophosphates in pest-control programs because of their low environmental persistence and toxicity. Ecotoxicological consequences of deltamethrin, particularly its effects on antioxidants in fish and other aquatic organisms, are not well understood. We investigated the effect of deltamethrin (0.75 microg/L) on antioxidants in a freshwater fish, Channa punctatus Bloch, using standard laboratory conditions. A single exposure for 48 h caused induction of various antioxidant enzymes and nonenzymatic antioxidants in kidney and liver. The induction of these antioxidants was not very prominent in gills. In fact, certain antioxidants were found to be depleted in gills. Catalase activity was decreased in all the tissues. Deltamethrin also induced lipid peroxidation in all the tissues, gills showing the highest levels. Glutathione, which is an established nonenzymatic antioxidant in fish, was significantly (P<0.001) increased in all the tissues. Ascorbic acid content increased in kidney and liver while it decreased in gills. The findings of the present investigation show that deltamethrin has oxidative-stress-inducing potential in fish, and gills are the most sensitive organs. It is also interesting to note that gills are the primary sites of deltamethrin absorption and their antioxidant potential is also very poor. The various parameters studied in this investigation can also be used as biomarkers of exposure to deltamethrin. It is suggested that appropriate ecotoxicological risk assessment should be made in the areas where deltamethrin is proposed to be used in pest control activities.
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Metallothionein (MT) gene expression was studied in different tissues, development stages and gender types of the mangrove killifish (Kryptolebias marmoratus). MT expression was also studied in a time-series experiment after exposure to... more
Metallothionein (MT) gene expression was studied in different tissues, development stages and gender types of the mangrove killifish (Kryptolebias marmoratus). MT expression was also studied in a time-series experiment after exposure to trace metals and endocrine-disrupting chemicals (EDCs). The brain showed the highest level of MT transcripts. Although all the development stage showed some level of MT expression, the adult hermaphrodites showed the highest expression which was significantly higher than the secondary males. In the trace metal-exposed fish, cadmium caused the strongest induction of MT. However, other trace metals such as copper and zinc also caused MT gene induction. All the EDCs suppressed the expression of MT gene, and the effect of EDCs were not gender-specific. K. marmoratus has previously shown its suitability as a model species for toxicity studies and cancer research. This study demonstrated utility of MT as biomarker in K. marmoratus. However, confounding factors such as age, gender, and tissue types appear to influence the MT expression. Response of trace and organic pollutants such as EDCs also varied greatly. These observations suggest that MT would be a specific biomarker of trace metal exposure in K. marmoratus and expression would be influenced by intrinsic factors.
Research Interests: Skeletal muscle biology, Biology, Breeding, Medicine, Gene expression, and 15 moreEnvironmental Sciences, Brain, Liver, Copper, Animals, Metallothionein, Cadmium, Eye, CHEMICAL SCIENCES, Biomarker, Cyprinidae, Gene Expression Regulation, Differential expression, reverse transcriptase polymerase chain reaction, and Medical and Health Sciences
The hermaphroditic fish Krytolebias marmoratus is a potential fish model for study of tumour development. Recently, sequences and expression of some oncogenes and tumor suppressor gene have been studied in K. marmoratus. To get a better... more
The hermaphroditic fish Krytolebias marmoratus is a potential fish model for study of tumour development. Recently, sequences and expression of some oncogenes and tumor suppressor gene have been studied in K. marmoratus. To get a better understanding of oncogene expression at different development stage, and in different tissues three R-ras genes were cloned and fully sequenced. Expression of these R-ras genes (R-ras1, R-ras2, R-ras3) was also studied in fish exposed to endocrine-disrupting chemicals (EDCs). Liver showed the highest level of expression compared to other tissues, even though each R-ras gene showed different expression patterns in tissues. Interestingly, in secondary male (ovary atresia stage), expression levels of three R-ras genes was lower compared to hermaphrodites. At different developmental stages, R-ras2 gene showed most pronounced expression at early embryogenesis but at stage 5 (hatchling stage) and juvenile stage, R-ras3 gene showed the highest expression. After the juvenile stage, R-ras1 gene was upregulated compared to other R-ras genes, which showed the highest expression at the hermaphroditic stage. When fish were exposed to 17-beta-estradiol (E2), a natural estrogen and tamoxifen, a nonsteroidal estrogen antagonist and three EDCs viz., 4-n-nonylphenol (NP), bisphenol A (BPA), and 4-tert-octylphenol (OP), all the three R-ras genes were induced, except in the fish exposed to tamoxifen. These results suggest that EDCs modulate the expression of R-ras genes and thus affect subsequent signal transduction and tumor development.
Research Interests: Biology, Modulation, Medicine, Gene expression, Biological Sciences, and 15 moreEnvironmental Sciences, FISH, Liver, bisphenol A, Endocrine disruptors, Female, Animals, Male, Gene, Endocrine Disruptors, Amino Acid Sequence, Estradiol, Estrogen antagonists, Medical and Health Sciences, and Expression pattern
The induction of heat shock proteins (Hsps) is considered as an important protective, ecophysiologically adaptive, and genetically conserved response to environmental stress in all organisms. Among the Hsps, the heat shock protein 70... more
The induction of heat shock proteins (Hsps) is considered as an important protective, ecophysiologically adaptive, and genetically conserved response to environmental stress in all organisms. Among the Hsps, the heat shock protein 70 (Hsp70) family members are most extensively studied for their characterization and induction in response to environmental stressors in a range of species. We studied expression of ten Hsp transcripts in response to heat treatment in an intertidal marine copepod Tigriopus japonicus and observed that expression of Hsp70 was more pronounced than other Hsps. Subsequently, cDNA and genomic sequences of T. japonicus Hsp70 (TJ-Hsp70) were worked out by molecular cloning techniques and phylogenetic relationship was analyzed. The bacterial expression of TJ-Hsp70 and its expression in response to metal and endocrine-disrupting chemical (EDC) exposures were also studied. The TJ-Hsp70 transformed bacteria showed increased thermotolerance compared to bacteria with vector only. All the trace metals (i.e. copper, silver, and zinc) caused a concentration-dependent increase in the expression of Hsp70 transcripts. Effect of EDCs on Hsp70 expression was differential. While 4-nonylphenol (NP) and 4-t-octylpheno (OP) caused downregulation, bisphenol A (BPA) caused upregulation. The promoter region of the genomic Hsp70 sequence contained putative xenobiotic response elements (XREs) indicating that TJ-Hsp70 regulation not only by temperature but also by xenobiotics. These findings suggest that in T. japonicus, Hsp70 has a conserved role of thermotolerance and its expression in response to xenobiotics exposure appears to be a protective response.
Research Interests: Genetics, Adaptation, Biology, Biological Sciences, Copepoda, and 15 moreEnvironmental Sciences, Copper, bisphenol A, Escherichia coli, Endocrine disruptors, Animals, Biomarker, Environmental Stress, Heat Shock, Endocrine Disruptors, Genome sequence, Heat Shock Protein, Amino Acid Sequence, Base Sequence, and Gene Expression Regulation
Research Interests: Genetics, Microbiology, Free Radicals, Biology, Medicine, and 15 moreGene expression, Free Radical, Biological Sciences, Environmental Sciences, Animals, Glutathione, Detoxification, Gene, Isoenzymes, Glutathione Transferase, Amino Acid Sequence, Full Length Movies, Enzyme Induction, Medical and Health Sciences, and Cadmium Chloride
Research Interests: Molecular Biology, Biology, Medicine, Biological Sciences, Antioxidants, and 15 moreEnvironmental Sciences, Copper, Escherichia coli, Animals, Glutathione, Biomarker, Biological markers, Enzyme activity, Amino Acid Profile, Glutathione Transferase, Amino Acid Sequence, Base Sequence, Full Length Movies, Medical and Health Sciences, and Expression pattern
Previous studies on the intertidal copepod Tigriopus japonicus have demonstrated that it is a suitable model species for the assessment of acute toxicities of marine pollutants. In order to standardize T. japonicus for use in... more
Previous studies on the intertidal copepod Tigriopus japonicus have demonstrated that it is a suitable model species for the assessment of acute toxicities of marine pollutants. In order to standardize T. japonicus for use in environmental risk assessment involving whole life cycle exposure, we tested nine pollutants for their effects on growth and reproduction during a two-generation life cycle exposure test. Nauplii (F 0) were exposed to a range of concentrations of each chemical in a static renewal culture system. Broods of the second generation (F1) were subsequently exposed to the same concentrations for one full life cycle. Of the seven traits (nauplius phase, development time, survival, sex ratio, number of clutch, nauplii per clutch and fecundity), only the length of the nauplius phase and development time showed a greater sensitivity to chemical exposure. Between the two sensitive traits, the period of the nauplius phase was more sensitive than cohort generation time. Biocides significantly increased the maturation period of nauplii as well as copepodids in F 0 generation. In this study, it was demonstrated that T. japonicus could also be used in reproduction and life cycle tests and it provides an opportunity for testing the chronic and subchronic toxic effects of marine pollutants. Further validation and harmonization in a multi-centric study involving other laboratories of the region will strengthen its use as a supplement to existing model species.
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We report here the full-length cDNA sequence of metallothionein (MT) gene from an anadromous river pufferfish, Takifugu obscurus (order: Tetradotiformes; family: Tetradontidae). Phylogenetic relationship analysis revealed that the... more
We report here the full-length cDNA sequence of metallothionein (MT) gene from an anadromous river pufferfish, Takifugu obscurus (order: Tetradotiformes; family: Tetradontidae). Phylogenetic relationship analysis revealed that the identified MT has high sequence similarity with many Perciformes fish species. The tissue distribution and concentration- and time-dependent expression of MT mRNA were studied in fish exposed to cadmium. Liver showed the highest level of MT gene expression followed by other tissues (brain, gill and kidney) in response to cadmium exposure. Muscle showed a weak expression response of MT gene. Time-course study revealed highest early phase (at 6h) expression in the brain and late persistence of induction in the intestine. MT mRNA expression showed a concentration-dependent expression in all the tissues. However, induction in brain and liver occurred at much lower concentrations as compared to other tissues. Our results demonstrate that MT in T. obscurus is induced by cadmium exposure which indicates that it plays a functionally conserved function of metal detoxification.
Research Interests: Biology, Environmental Monitoring, Medicine, Gene expression, Multidisciplinary, and 15 morePhylogeny, Animals, Detoxification, Metallothionein, Gene, Cadmium, Molecular cloning, mRna expression levels, Biomarker, Amino Acid Sequence, Base Sequence, Full Length Movies, Molecular Sequence Data, reverse transcriptase polymerase chain reaction, and mRNA expression
Research Interests: Biochemistry, Biology, Gene expression, Copepoda, Antioxidants, and 15 moreCopper, Escherichia coli, Animals, Antioxidant, Heavy Metal, Glutathione, Detoxification, Hydrogen Peroxide, Copepod, Amino Acid Profile, Glutathione Transferase, Environmental Pollutants, Amino Acid Sequence, Base Sequence, and Full Length Movies
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Research Interests: Chemistry, Prostate Cancer, Oxidative Stress, Medicine, Free Radical, and 15 moreAntioxidants, Black Tea, Animals, Antioxidant, Male, Glutathione, Catalase, Prostate, Lipid peroxidation, Camellia sinensis, Antioxidant enzyme, Plant extracts, Oxidative Damage, Glutathione Transferase, and Glutathione Reductase
Research Interests: Ecotoxicology, Aquatic Toxicology, Crustacea, Biology, Gene expression, and 15 moreBiological Sciences, Copepoda, Environmental Sciences, Copper, Animals, Growth and development, Detoxification, Gene, CHEMICAL SCIENCES, Environmental Risk Assessment, Copepod, Environment, Chronic Toxicity, Gene Expression Regulation, and Gene expression profiling
Research Interests: Ecotoxicology, Aquatic Toxicology, Biology, Biological Sciences, Environmental Sciences, and 15 moreCopper, Escherichia coli, Animals, Heavy Metal, Glutathione, CHEMICAL SCIENCES, Biomarker, Biological markers, Amino Acid Profile, Glutathione Transferase, Amino Acid Sequence, Base Sequence, Geologic Sediments, Full Length Movies, and Dinitrochlorobenzene
Cancer of the prostate gland (CaP), the most common invasive malignancy and a major cause of cancer related deaths in male population in the USA, is an ideal candidate disease for chemoprevention because it is typically