Biogenesis of silver nanoparticles using endophytic fungus Pestalotiopsis microspora and evaluation of their antioxidant and anticancer activities.

An endophytic fungal strain isolated from the leaves of Gymnema sylvestre was identified as Pestalotiopsis microspora VJ1/VS1 based on nucleotide sequencing of internal transcribed spacer region (ITS 1-5.8S-ITS 2) of 18S rRNA gene (NCBI accession number KX213894). In this study, an efficient and ecofriendly approach has been reported for the synthesis of silver nanoparticles (AgNPs) using aqueous culture filtrate of P. microspora. Ultraviolet-visible analysis confirmed the synthesis of AgNPs by showing characteristic absorption peak at 435 nm. Fourier transform infrared spectroscopy analysis revealed the presence of phenolic compounds and proteins in the fungal filtrate, which are plausibly involved in the biosynthesis and capping of AgNPs. Transmission electron microscopy (TEM) showed that the AgNPs were spherical in shape of 2-10 nm in size. Selected area electron diffraction and X-ray diffraction studies determined the crystalline nature of AgNPs with face-centered cubic (FCC) lattice phase. Dynamic light scattering analysis showed that the biosynthesized AgNPs possess high negative zeta potential value of -35.7 mV. Biosynthesized AgNPs were proved to be potential antioxidants by showing effective radical scavenging activity against 2,2'-diphenyl-1-picrylhydrazyl and H2O2 radicals with IC50 values of 76.95±2.96 and 94.95±2.18 µg/mL, respectively. The biosynthesized AgNPs exhibited significant cytotoxic effects against B16F10 (mouse melanoma, IC50 =26.43±3.41 µg/mL), SKOV3 (human ovarian carcinoma, IC50 =16.24±2.48 µg/mL), A549 (human lung adenocarcinoma, IC50 =39.83±3.74 µg/mL), and PC3 (human prostate carcinoma, IC50 =27.71±2.89 µg/mL) cells. The biosynthesized AgNPs were found to be biocompatible toward normal cells (Chinese hamster ovary cell line, IC50 =438.53±4.2 µg/mL). Cytological observations on most susceptible SKOV3 cells revealed concentration-dependent apoptotic changes that include cell membrane blebbing, cell shrinkage, pyknotic nuclei, karyorrhexis followed by destructive fragmentation of nuclei. The results together in this study strongly provided a base for the development of potential and versatile biomedical applications of biosynthesized AgNPs in the near future.

Toxicomorphomics and toxicokinetics of quinalphos on embryonic development of zebrafish (Danio rerio) and its binding affinity towards hatching enzyme, ZHE1.

This study outlines the toxic effects of Quinalphos (QP), an organophosphrous insecticide on the development of zebrafish (Danio rerio) embryos, with special emphasis on toxicomorphomics and toxicokinetics of target enzyme, AChE. A range of concentrations was used to elucidate the median lethal concentration (LC50) of Quinalphos. Furthermore, embryos were exposed to two sub-lethal concentrations LC10 (0.66mg/L) and LC20 (1.12mg/L) along with a median lethal concentration (3.0mg/L) for 96h. Several morphological aberrations like lordosis, kyphosis, scoliosis, heart edema, breaks in the neuronal tube and underdeveloped facial parts were noticed, which were of concentration and time dependent. The QP has adequately hindered hatching process during the course of exposure which was upheld by the in silico docking studies with hatching enzyme, ZHE1. The length of hatchlings at 96h in LC50 concentration was significantly reduced to 47% compared to control. A significant pericardial effusion (5 to 16 fold) was observed in >90% of LC50 treated groups. Morphological changes in heart lead to the bradycardia, which ultimately leading to heart failure in some cases. The swimming behavior was significantly diminished in relation to the inhibition of AChE levels. From the in vitro kinetic studies, the kinetic constants Km, Vmax and inhibitory concentration Ki (4.45×10-5M) was determined which supported the competitive nature of QP.

Immunogenicity of a new routine vaccination schedule for global poliomyelitis prevention: an open-label, randomised controlled trial.

BACKGROUND: Polio eradication needs a new routine immunisation schedule--three or four doses of bivalent type 1 and type 3 oral poliovirus vaccine (bOPV) and one dose of inactivated poliovirus vaccine (IPV), but no immunogenicity data are available for this schedule. We aimed to assess immunogenicity of this vaccine schedule. METHODS: We did an open-label, randomised controlled trial in four centres in India. After informed consent was obtained from a parent or legally acceptable representative, healthy newborn babies were randomly allocated to one of five groups: trivalent OPV (tOPV); tOPV plus IPV; bOPV; bOPV plus IPV; or bOPV plus two doses of IPV (2IPV). The key eligibility criteria were: full-term birth (≥37 weeks of gestation); birthweight ≥2·5 kg; and Apgar score of 9 or more. OPV was administered at birth, 6 weeks, 10 weeks, and 14 weeks; IPV was administered intramuscularly at 14 weeks. The primary study objective was to investigate immunogenicity of the new vaccine schedule, assessed by seroconversion against poliovirus types 1, 2, and 3 between birth and 18 weeks in the per-protocol population (all participants with valid serology results on cord blood and at 18 weeks). Neutralisation assays tested cord blood and sera collected at 14 weeks, 18 weeks, 19 weeks, and 22 weeks by investigators masked to group allocation. This trial was registered with the India Clinical Trials Registry, number CTRI/2013/06/003722. FINDINGS: Of 900 newborn babies enrolled between June 13 and Aug 29, 2013, 782 (87%) completed the per-protocol requirements. Between birth and age 18 weeks, seroconversion against poliovirus type 1 in the tOPV group occurred in 162 of 163 (99·4%, 95% CI 96·6-100), in 150 (98·0%, 94·4-99·6) of 153 in the tOPV plus IPV group, in 153 (98·7%, 95·4-99·8) of 155 in the bOPV group, in 155 (99·4%, 96·5-100) of 156 in the bOPV plus IPV group, and in 154 (99·4%, 96·5-100) of 155 in the bOPV plus 2IPV group. Seroconversion against poliovirus type 2 occurred in 157 (96·3%, 92·2-98·6) of 163 in the tOPV group, 153 (100%, 97·6-100·0) of 153 in the tOPV plus IPV group, 29 (18·7%, 12·9-25·7) of 155 in the bOPV group, 107 (68·6%, 60·7-75·8) of 156 in the bOPV plus IPV group, and in 121 (78·1%, 70·7-84·3) of 155 in the bOPV plus 2IPV group. Seroconversion against poliovirus type 3 was achieved in 147 (90·2%, 84·5-94·3) of 163 in the tOPV group, 152 (99·3%, 96·4-100) of 153 in the tOPV plus IPV group, 151 (97·4%, 93·5-99·3) of 155 in the bOPV group, 155 (99·4%, 96·5-100) of 156 in the bOPV plus IPV group, and 153 (98·7%, 95·4-99·8) of 155 in the bOPV plus 2IPV group. Superiority was achieved for vaccine regimens including IPV against poliovirus type 3 compared with those not including IPV (tOPV plus IPV vs tOPV alone, p=0·0008; and bOPV plus IPV vs bOPV alone, p=0·0153). 12 serious adverse events occurred (six in the tOPV group, one in the tOPV plus IPV group, three in the bOPV group, zero in the bOPV plus IPV group, and two in the bOPV plus 2IPV group), none of which was attributed to the trial intervention. INTERPRETATION: The new vaccination schedule improves immunogenicity against polioviruses, especially against poliovirus type 3. FUNDING: WHO, through a grant from Rotary International (grant number 59735).

Isolation, semi-synthesis and bio-evaluation of spatane derivatives from the brown algae Stoechospermum marginatum.

A comprehensive investigation of chemical constituents from brown algae Stoechospermum marginatum yielded ten known spatane compounds (1-10). To develop the compound libraries on these scaffolds, a series of semi synthetic derivatives was prepared (1a-1d, 2a, 4a, 11 and 12) and investigated for their anti-microbial and anticancer activities. The results indicated that compounds 2a, 4, 1b and 4a exhibited potent cytotoxic activities against B16F10 cancer cell line with IC50 values of 3.28, 3.45, 3.62 and 4.11 µg/ml respectively, which are comparable to the standard drug (etoposide IC50=4.12 µg/ml). In addition, 4 and 1b were also manifested potent antimicrobial activities against tested bacterial and fungal strains. This is the first Letter on the synthesis and biological activities of these novel derivatives.

The role of vitamin C as antioxidant in protection of biochemical and haematological stress induced by chlorpyrifos in freshwater fish Clarias batrachus.

The study was conducted to explore the modulatory effects of chlorpyrifos and protective role of vitamin C in tissues of Clarias batrachus. Treatments include E1 group (basal diet plus 1.65mgL(-1) CPF) and E2 group (basal diet+200mgkg body weight vitamin C and 1.65mgL(-1) CPF) along with a control group of fishes (fed on basal diet only). After 1, 7, 15, and 30d of treatment, fish tissues (brain, blood and liver) were used for the estimation of growth, biochemical and haematological parameters. The results of E1 group indicated significantly lower weight gain and survival rate. Brain AChE activity was inhibited. The RBC, Hb, respiratory burst activity, total protein and HSI were also reduced whereas WBC count, plasma glucose and haematocrit were elevated. In contrast, liver glycogen content, lactate dehydrogenase, alkaline and acid phosphatase activities were inhibited and malate dehydrogenase, aspartate, alanine amino transferase were enhanced. The E2 group of fish exhibited significant improvement in growth, survival, haematological indices, brain AChE, liver glycogen and oxidative enzyme activity. The findings support that dietary vitamin C supplementation might be helpful in abrogation of chlorpyrifos toxicity and improves growth, survival, biochemical and haematological conditions in fishes.

Toxicity effects of profenofos on embryonic and larval development of Zebrafish (Danio rerio).

The aim of the present study was to evaluate the developmental toxicity of profenofos to early developing Zebrafish (Danio rerio) embryos (4h post fertilization) in a static system at 1.0 to 2.25mg/L. Median lethal concentrations (LC50) of profenofos at 24-h, 48-h, 72-h and 96-h were determined as 2.04, 1.58, 1.57 and 1.56 mg/L, respectively. The hatching of embryos were recorded at every 12h interval and the median hatching time (HT50) was also calculated for each concentration. In a separate set of experiments, 96-h LC10 (0.74 mg/L) and LC50 (1.56 mg/L) concentrations were used to assess the developmental toxicity in relation to behavior, morphology, and interactions with the targeted enzyme acetylcholinesterase. Live video-microscopy revealed that the profenofos exposed embryos exhibited an abnormal development, skeletal defects and altered heart morphology in a concentration-dependent manner, which leads to alterations in the swimming behavior of hatchlings at 144-h, which indicate that developing zebrafish are sensitive to profenofos.

A Japanese Encephalitis Vaccine From India Induces Durable and Cross-protective Immunity Against Temporally and Spatially Wide-ranging Global Field Strains.

BACKGROUND: Japanese encephalitis (JE) is a vaccine-preventable acute disease. We report the results of a phase 2/3 trial of JENVAC, a Vero cell-derived vaccine developed using an Indian strain of JE virus (JEV). METHODS: JENVAC was administered in 2 doses 28 days apart, and immunogenicity was compared to that from a single dose of SA-14-14-2, the only approved JE vaccine and regimen at the time in India. RESULTS: After both the doses, seroconversion and seroprotection were >90% for JENVAC. For SA-14-14-2, seroconversion and seroprotection were 57.69% and 77.56%, respectively, on day 28 and 39.74% and 60.26%, respectively, on day 56. The geometric mean titers at day 28 and day 56 were 145.04 and 460.53, respectively, for JENVAC and 38.56 and 25.29, respectively, for SA-14-14-2. With a single dose of JENVAC, seroprotection titers lasted at least 12 months in >80% of the subjects. Following receipt of 2 doses, 61.17% of subjects retained seroprotection titers at 24 months, and immunogenicity criteria were higher than that for SA-14-14-2 at 12, 18, and 24 months each. Sera from JENVAC subjects neutralized JEV genotypes I, II, III, and IV equally well. Adverse events were not significantly different between the 2 vaccines. CONCLUSIONS: JENVAC elicits long-lasting, broadly protective immunity. CLINICAL TRIALS REGISTRATION: CTRI/2011/07/001855.

Evaluation of the biochemical stress response to chlorpyrifos in tissues of the edible crab Barytelphusa guerini: withdrawal of exposure improves the nutritional value.

The sublethal stress of the organophosphate insecticide chlorpyrifos was investigated in different tissues of the freshwater crab (Barytelphusa guerini). Crabs were exposed to 1/3 of LC50 concentrations for 7, 14, 21, and 28 days. After 28 days, they were released into fresh water and kept for 18 days for recovery. The study was conducted by estimating total proteins, amino acids, ammonia, urea, and glutamine levels, and protease, transaminases, and phosphatases activities. Total proteins level was decreased whereas amino acids and ammonia were increased. The urea content was decreased in all tissues and glutamine exhibited a mixed response. Protease activities and those of alanine and aspartate aminotransferase, respectively, were elevated. Acid phosphatase activity was reduced in hepatopancreas and brain and induced in gills and muscle. Alkaline phosphatase activity was enhanced in gills and hepatopancreas and reduced in muscle and brain. The crabs recovered from the biochemical stress caused by chlorpyrifos after their release into fresh water.

Hybrids of privileged structures benzothiazoles and pyrrolo[2,1-c] [1,4]benzodiazepin-5-one, and diversity-oriented synthesis of benzothiazoles.

Privileged structures like Benzothiazole and Pyrrolobenzodiazepine offer wonderful opportunity to explore in anti-cancer drug discovery as a mean to counter drug-resistance problem. BT-PBD hybrids and diverse BT derivatives have been synthesized and their in vitro cytotoxic activities were screened against five cancer cell lines have been discussed. The novel compounds showed promising results as compared with the marketed drug etoposide and could well be used in future anti-cancer drug development studies.

Synthesis and cytotoxic evaluation of thiourea and N-bis-benzothiazole derivatives: a novel class of cytotoxic agents.

Benzothiazolyl thiocarbamides has been achieved using a catalytic amount of 4-dimethylaminopyridine (DMAP) followed by its chemoselective oxidative cyclization with 1,3-di-n-butylimidazolium tribromide[bbim][Br(3)] to afford the N-bis-benzothiazole derivatives. All the synthesized compounds were evaluated for cytotoxic activity against two human monocytic cell lines (U 937, THP-1) and a mouse melanoma cell line (B16-F10). Based on their IC(50) values, the majority of the benzothiazolyl thiocarbamides and N-bis-benzothiazoles had significant antiproliferative activity on U 937 and B16-F10 cells, the compounds 3b, 3e, 3f, 3k, 6c and 6h were found to be the most active. The present findings indicate clearly that the compound 3e exhibited more antiproliferative activity on U 937 cells than the standard molecule, etoposide. Nevertheless, these compounds have shown comparatively less cytotoxicity towards THP-1 cells.

Toxic impact of two organophosphate insecticides on biochemical parameters of a food fish and assessment of recovery response.

Sublethal effects of chlorpyrifos (CPF) and monocrotophos (MCP) on fish biochemical constituents were investigated along with the assessment of recovery response after cessation of intoxication. The fish, Clarias batrachus were exposed to 1.656 mg(-l) and 2.114 mg(-l) of CPF and MCP for 28 days. After 28 days, they were released in freshwater and allowed to recover for 21 days. The CPF exposure resulted in the decrease of carbohydrate and glycogen content, whereas MCP intoxication caused mixed response. Pyruvate and lactate contents were altered under the stress of CPF and MCP. Recovery of these alterations was observed after the cessation of toxicity. Exposure of C. batrachus to CPF and MCP resulted in decreased activity of lactate dehydrogenase in the kidney, liver and muscle but its activity increased in the gills. The CPF caused inhibition of succinate dehydrogenase enzyme in all tissues. Induction in the activity of malate dehydrogenase was caused by both insecticides. Glycogen phosphorylase a was induced in all tissues, whereas glycogen phosphorylase ab showed both induction and inhibition. Of the two insecticides, CPF was more toxic and the recovery response was less. These results are important in the assessment of the risk caused by organophosphate insecticides on nontarget organisms, especially the food fish.

In vivo impact of monocrotophos on biochemical parameters of a freshwater fish during subacute toxicity and following cessation of exposure to the insecticide.

In vivo toxicity of monocrotophos on key metabolites and enzymes of the protein metabolism was investigated in important tissues of the freshwater fish Clarias batrachus. Fish were exposed to 1/10 and 1/20 of LC50 concentration for 28 days. After 28 days of exposure, some fish were transferred to monocrotophos-free water and kept in the same for 21 days (recovery period) in order to study the recovery response. Total protein, amino acid, and ammonia contents were decreased in gill, kidney, liver, and muscle tissues, and recovery was slight at the end of 21 days of transfer of fish into freshwater. Urea and glutamine levels were elevated, except in kidneys, and recovered at the end of the recovery period. The activities of protease, transaminase, and phosphatase enzymes were elevated in all tissues during 28 days of exposure and at both concentrations. Recovery of the activity of enzymes was more significant at the lower concentration as compared to the higher concentration.

Diversity-oriented synthesis of quinolines via Friedländer annulation reaction under mild catalytic conditions.

An efficient and practical method has been manifested for the diversity-oriented synthesis of quinolines via Friedländer annulation reaction for the generation of a wide range of structurally interesting and pharmacologically significant compounds by using ceric ammonium nitrate as a catalyst (10 mol %) at ambient temperature in 45 min. A variety of functional groups are introduced at various positions of the quinoline moiety, and further the diversity of the core skeleton was expanded at R(1) and R(2) positions by the synthesis of various hybrids. Initial screening of the compounds for cytotoxicity against a series of cancer cell lines showed promising results.

Toxic effects of chlorpyrifos on antioxidant enzymes and target enzyme acetylcholinesterase interaction in mosquito fish, Gambusia affinis.

The recovery effect of chlorpyrifos (CPF) on antioxidant enzymes, locomotor behaviour and the target enzyme acetylcholinesterase (AChE) interaction were studied after exposure to 297µgL(-1) (LC(50) for 96h) in mosquito fish, Gambusia affinis. Activities of the antioxidant enzymes-superoxide dismutase, catalase, glutathione reductase in viscera, and AChE in brain were inhibited at 96h of exposure. However, induction in lipid peroxidation was observed. The antioxidant levels were restored to near control by 16-18 days. Similarly, swimming speed and AChE were also recovered but comparatively needs longer period. In vitro AChE study indicated that CPF alters the apparent K(m) values, resulting in a competitive type of inhibition and the inhibitory constant K(i) was found to be 4.57×10(-4)M. The results showed that the organophosphate CPF besides its inhibitory effect on target enzyme AChE also inhibits antioxidant enzymes, which can be used as biomarkers in the pesticide-contaminated aquatic streams.

Locomotor behavioral response of mosquitofish (Gambusia affinis) to subacute mercury stress monitored by video tracking system.

Locomotor behavior is commonly affected by contaminants, and the pattern of fish swimming is a highly organized species-specific response. In the current study, we examined the locomotor behavioral response of the mosquitofish, Gambusia affinis, which was exposed to a sublethal concentration (LC(5), 20 microg/L) of mercuric chloride (HgCl2) for 28 days and monitored using a computer vision system. The EthoVision video tracking system for automation of behavioral studies at regular intervals revealed abnormal locomotor behavior such as reduction in swimming speed (cm/s) and distance traveled per unit time. The effects of this metal on the gill morphology and bioaccumulation in different body parts were also investigated. High-resolution microscopy studies revealed abnormal gill morphology, with fusion of primary lamellae along with deep lesions and erosions in the secondary lamellae. The bioaccumulation concentrations in head, body, and viscera were determined by cold vapor atomic absorption spectrometric technique at regular intervals. The results indicated that the accumulation of mercury was the highest in viscera followed by head and body, with bioconcentration factors (BCFs) of 3.99, 2.18, and 1.57 and uptake rate constants (k1) of 17.91, 11.02, and 8.13, respectively. These observations indicate that alterations in fish behavior under subacute stress can provide important information useful in predicting the stress.

Acetylated pseudoguaianolides from Parthenium hysterophorus and their cytotoxic activity.

Chemical examination of the flowers of Parthenium hysterophorus has resulted in the isolation of four acetylated pseudoguaianolides along with several known constituents. The structures of the compounds were derived from detailed studies of their spectral (1D and 2D NMR and FABMS) data and by comparison of the values with those of parthenin, a major known constituent of the plant. The cytotoxic activity of parthenin and the constituents was evaluated using Jurkat (human: T lymphocyte; acute T cell leukemia), HL-60 (human leukemia) and Hela (human cervical carcinoma) cells.

Biochemical alterations in euryhaline fish, Oreochromis mossambicus exposed to sub-lethal concentrations of an organophosphorus insecticide, monocrotophos.

The euryhaline fish, Oreochromis mossambicus was exposed to sub-lethal concentration (1.15 mg l(-1)) of a organophosphorus insecticide, monocrotophos (MCP) for 30 days and allowed to recover for seven days. Alanine aminotransferase (ALAT), aspartate aminotransferase (AAT), acid phosphatase (AcP), alkaline phosphatase (ALP), glycogen, lactate dehydrogenase (LDH), Reduced glutathione (GSH), gluthathione-S-transferase (GST) and acetylcholinesterase (AChE), were assayed in plasma and different tissues at regular intervals of day -3, -7, -15, -30 and after recovery period of seven days. The ALAT and AAT activities were increased in plasma and kidney, where as liver and gill showed decrease. Increase in AcP and ALP activities were observed in plasma, gill and kidney, and reduction of 42% and 50% was observed in liver. Glycogen was depleted in plasma, liver and gill indicates of typical stress related response of the fish with pesticide. LDH activity was decreased in liver and muscle, indicating tissue damage and muscular harm, but a significant increase in LDH activity in gill and brain was observed. Depletion in GSH activity was observed in all the tissues, there by enhancing the lipid peroxidation resulting in cell damage. The induction in hepatic GST levels indicates the protection against the toxicity of xenobiotic-induced lipid peroxidation. There was a significant recovery in all the above biochemical parameters studied in plasma and different tissues, after seven days recovery period. These results revealed that MCP affects the intermediary metabolism of O. mossambicus and that the assayed enzymes can work as good biomarkers of organophosphorus contamination.

Petrosia testudinaria as a biomarker for metal contamination at Gulf of Mannar, southeast coast of India.

Coastal marine ecosystems in many parts of the world are under unrelenting stress caused by urban development, pollutants and other ecological impacts such as building of infrastructure, land reclamation for port and industrial development, habitat modification, tourism and recreational activities. The present work is a first extensive field study using the marine sponge, Petrosia testudinaria as a biomarker to detect heavy metal pollution between near and off shore environment of 'Gulf of Mannar', India. Sponges were collected from near shore (0.5-1 km) and offshore (5-7 km), locations and their metal concentrations were determined by inductively coupled plasma-mass spectrometry (ICPMS). Our results show that the near shore sponge accumulated greater concentrations of heavy metals (Al, Fe, Mn, As, Ni, Co, Cu, Se) ranging from 0.13 to 64 times higher concentration than the sponges located away from the shore. The results indicate that the accumulated metals alter the macromolecule composition (sugars, proteins and lipids) in near shore sponges. Frequent monitoring is necessary to assess the eco-health of the marine environment by choosing bioindicator species like sponges, which provide accurate, reliable measurement of environmental quality.

Sublethal effects of monocrotophos on locomotor behavior and gill architecture of the mosquito fish, Gambusia affinis.

Subacute studies of monocrotophos [Dimethyl (E)-1-methyl-2-(methyl-carbamoyl) vinyl phosphate] on mosquito fish, Gambusia affinis, were carried out in vivo for 24 days to assess the locomotor behavior, structural integrity of gill, and targeted enzyme acetylcholinesterase (AChE, EC: 3.1.1.7) interactions. Monocrotophos (MCP) can be rated as moderately toxic to G. affinis, with a median lethal concentration (LC(50)) of 20.49 +/- 2.45 mgL(-1). The fish exposed to sublethal concentration of LC(10) (7.74 mgL(-1)) were under stress and altered their locomotor behavior, such as distance traveled per unit time (m min(-1)) and swimming speed (cm sec(-1)) with respect to the length of exposure. Inhibition in the activity of brain AChE and deformities in the primary and secondary lamellae of gill may have resulted in failure of exchange of gases. The maximum inhibition of 95% of AChE activity was observed on days 20 and 24. Morphological aberrations in the gills were also studied during exposure to the sublethal concentration of monocrotophos for a period ranging from 8 to 24 days. The extent of damage in gill was dependent on the duration of exposure. The findings revealed that inhibition in brain AChE activity and structural alteration in gill were responsible for altering the locomotor behavior of exposed fish.

Changes in behavior and brain acetylcholinesterase activity in mosquito fish, Gambusia affinis in response to the sub-lethal exposure to chlorpyrifos.

Sub-lethal studies of chlorpyrifos, O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate on mosquito fish, Gambusia affinis were carried out in vivo, for 20 days to assess the locomotor behavior in relation to bioaccumulation and interaction with a targeted enzyme, acetylcholinesterase (AChE, EC: 3.1.1.7). Fish exposed to sub-lethal concentration of 60 microg/L (1/5 of LC 50) were under stress, and reduced their locomotor behavior like distance travelled per unit time (m/min) and swimming speed (cm/sec) with respect to the length of exposure. The alteration in locomotor behavior of fish may be due to an accumulation of acetylcholine (ACh), a neurotransmitter at synaptic junctions, due to the inhibition of AChE enzyme activity (40 to 55%) in brain and also bioaccumulation of the toxicant in different parts of fish. The bioaccumulation values indicated that the accumulation of chlorpyrifos was maximum in viscera followed by head and body. The average bio-concentration values are 0.109, 0.009 and 0.004 microg/g for viscera, head and body with depuration rates of 2.24, 1.69 and 0.39 ng/h respectively. It is evident from the results that the sub-lethal concentration [1/5 of LC 50; equivalent to Lowest Observed Effect Concentration (LOEC)] of chlorpyrifos can able to alter the locomotor behavior of G. affinis in relation to the length of exposure. The findings revealed that the locomotor activity of test organism could be considered as a suitable marker to evaluate the affect of toxicant even at LOEC levels.