Zoology
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Item Use of liver histological alterations and erythrocytic nuclear abnormalities of two native fish in Kelani River, Sri Lanka as biomarkers for pollution impact assessments(Journal of the National Science Foundation of Sri Lanka, 2020) Ruvinda, K.; Pathiratne, A.Multi-biomarker approach is recognised as a complementary tool for environmental monitoring studies to better appraise how pollutants affect ecosystems. This study examined histological alterations in the liver tissues and nuclear abnormalities in the peripheral erythrocytes of two native fish species inhabiting the Kelani River (Etroplus suratensis and Dawkinsia singhala) as ‘effect biomarkers’ for assessing pollution impacts. Surface water and native fish were sampled from two polluted sites in the lower reach (Kaduwela and Mattakkuliya) and a less polluted site in the upper reach (Ruwanwella) of the river covering rainy and dry periods. Physico-chemical analyses of surface water confirmed an increasing trend of pollution towards the lower reach of the river. Significantly greater liver histopathologic condition indices and erythrocytic nuclear abnormality frequencies (p < 0.05) were found in the fish inhabiting lower reaches of the river compared to those in the upper catchment at Ruwanwella. Biomarker responses revealed that the fish populations inhabiting the polluted sites in the river are under stress especially due to hepatic damage and genotoxicity. The results suggest that endemic and nationally threatened fish species in the riverine ecosystem may be at risk due to the contaminant stress under long term exposure. This study supports utility of erythrocyte nuclear abnormality and liver histopathological biomarker responses of native fish as cost effective tools for the identification of potential biological hazards of river pollution.Item Toxic hazards of industrial waste receiving canal system in the lower catchment of Kelani River basin, Sri Lanka(2020) Kuruppuarachchi, H.; Pathiratne, A.Assessing toxic hazards associated with polluted riverine ecosystems is essential for the development of effective strategies for their management. The present study explored the combined utility of bioassay responses of the plant, Allium cepa and surface water physico-chemical characteristics to assess the toxic hazards of an industrial waste receiving canal system located in the lower catchment of the Kelani River basin, Sri Lanka. Surface water samples from seven sites, viz. Maha Ela upstream (Site A), Manikagara Ela (Site B), Manikagara Ela - Maha Ela confluence (Site C), Maha Ela downstream (Site D), Maha Ela - Kelani River confluence (Site E), River downreach (Site F) and upper-reach (Site R) were analysed on three occasions in 2015 covering dry and wet periods. Irrespective of the sampling periods, exposure of A. cepa bulbs to water from the Sites B, C, D and E resulted in root growth retardation and mitosis depression (p < 0.05) in the root meristem signifying toxic/cytotoxic hazards. Occasional micronuclei evolution and nuclear bud induction were also found in the root cells exposed to Site B and C samples indicating genotoxicity. Toxic hazards were somewhat reduced towards down-reach of the river, which may be associated with self-depuration effects. The principal component analysis based on surface water characteristics and bioassay responses revealed clear separations of Sites B and C from the other sites. The results revealed that water quality of Manikagara Ela and Maha Ela needs improvements considering toxic hazards to the riverine ecosystem and human healthItem Comparison of Sensitivity of Tropical Freshwater Microalgae to Environmentally Relevant Concentrations of Cadmium and Hexavalent Chromium in Three Types of Growth Media(Bull Environ Contam Toxicol, 2020) Munagamage, T.; Rathnayake, I.V.N.; Pathiratne, A.Sensitivity of tropical freshwater microalgae (Mesotaenium sp., Chlorococcum sp. and Scenedesmus sp.) to environmentally relevant concentrations of hexavalent chromium (Cr6+) and cadmium (Cd2+) was compared individually in three growth media viz. Bold’s Basal Medium (BBM), Test Medium 1 (TM1) and Test Medium 2 (TM2) based on fluorescence reduction. Free metal content of growth media was determined by Visual MINTEQ (version 3.1). After 24 h, relative fluorescence of microalgae in the three media decreased with increased metal concentration showing a concentration dependent graded toxicity response. All microalgae were more sensitive to the metals when grown in TM1, when compared, more sensitive to Cr6+ than Cd2+. Metal speciation indicated that TM1 and TM2 media have higher percentage of bioavailable Cd2+ than BBM, and chromium was present mainly as CrO42− and HCrO4−. The results suggest that the TM1 medium is more suitable under short term exposure of microalgae to metals in environmental monitoring.Item Cadmium and arsenic levels in edible fi shes, Oreochromis niloticus (Nile tilapia) and Ompok bimaculatus (butter catfi sh) from Padaviya Reservoir, Sri Lanka and human health risk assessment associated with their dietary exposure(2020) Weerasekara, K. A. W. S.; Pathiratne, A.; Kithsiri, H. M. P.Consumption of fi sh contaminated with toxic heavy metals is a threat to human health. Cadmium and arsenic are suspected as potential risk factors for chronic kidney disease of unknown aetiology (CKDu), which is highly prevalent in agricultural settlements in dry zone districts of Sri Lanka causing a severe public health crisis. Objectives of this study were (i) to determine cadmium and arsenic levels in muscle, liver and kidney of two edible fi shes (Nile tilapia and butter catfi sh) from the Padaviya reservoir located in the North Central Province, Sri Lanka where CKDu is highly prevalent and (ii) to assess the potential human health risks associated with the dietary exposure through edible muscle of these fi shes. Cadmium and arsenic levels of the tissues in the two fi sh species were determined using inductively coupled plasma mass spectrometry. In both fi sh species, highest cadmium levels were found in kidney (p < 0.05) whereas no signifi cant tissue specifi c diff erences (p > 0.05) were evident for arsenic. In the edible muscle, the maximum detected cadmium level in Nile tilapia was 0.1 mg/kg in wet weight. However, cadmium levels in the muscle of all Butter catfi sh were < 0.05 mg/kg. Arsenic levels in the muscle of all Nile tilapia and Butter catfi sh were < 0.05 mg/kg. Cadmium contents in muscle of most fi shes and arsenic contents in all fi shes (n = 60) were within the maximum permissible limits set by the international food standards regulatory authorities. Based on the estimated daily intake and target hazard quotients (< 1) for lifetime exposure, it is highly unlikely that cadmium and arsenic contents of the muscle meat of these fi shes would pose human health risks to moderate level consumers.Item Application of cytogenetic model Allium cepa for screening potential cytogenotoxicity of herbal-based hair dyes(Journal of Environmental Science and Health, 2020) Nawalage, K. S.; Pathiratne, A.Plant models may be useful as test organisms for initial screening of potential toxicity of personal care products. The objective of the present study was to assess the efficacy of the Allium cepa (common onion) test system as a bioanalytical tool for screening potential cytotoxicity and genotoxicity of herbal-based hair dye formulations. Exposure of black hair dye formulations for 48 hours resulted in root growth retardation and mitosis suppression in the root meristems of A. cepa bulbs indicating concentration dependent cytotoxicity. At the 72 hour post exposure, cytotoxic effects on the roots were reduced but not recovered completely signifying prolong toxic action of the hair dyes. The condensed nuclei was the most frequent nuclear abnormality found in the dye exposed root meristematic cells indicating the cell death process. Induction of micronuclei and chromosomal aberrations in the root meristematic cells even at the post exposure stage indicates persistent genotoxicity of the hair dyes which may be attributed to the interactive effects of chemical mixtures present in the commercial hair dye formulations. The results revealed that A. cepa test system is an effective bioanalytical tool for screening cytogenotoxicity of commercial hair dye formulations.Item In vitro metabolism of benzene, toluene, and xylene in rat liver(North Dakota State Univ., Fargo (USA)., 1985) Pathiratne, A.A headspace gas chromatographic method was used to study the metabolism of benzene, toluene, and m-xylene in rat liver. Metabolism of benzene was lower than that of toluene, or m-xylene. Investigating metabolic rates of subcellular fractions, it was found that glutathione and glutathione S-transferase in the cytosol are involved in metabolism of benzene and toluene by microsomes. When both benzene and toluene are present in the incubation medium, they act as inhibitors of each others metabolism. Toluene and m-xylene metabolism were induced by the pretreatment of rats with phenobarbital (75 mg/kg), or 3-methylcholanthrene (25 mg/kg), or Aroclor 1254 (75 mg/kg) for 3 days, whereas benzene metabolism was not induced by all pretreatments. Another series of experiments was conducted to compare the effects of benzene, toluene, and xylene pretreatment on liver metabolism. In vivo metabolism of /sup 14/C-toluene and possible covalent binding of /sup 14/C-toluene to microsomes were also investigated. /sup 14/C-toluene when incubated with liver microsomes in the presence of a NADPH generating system formed benzylalcohol and cresols. Some of the radioactivity was covalently bound preferentially to microsomal proteins. The binding process required cytochrome P-450 dependent mixed function oxidases. This study suggests that toluene is metabolized to several reactive intermediates by liver microsomal enzymes and these metabolites are responsible for the covalent binding to macromolecules which represents a subcellular mechanism by which toluene may express its own in vivo toxicity.Item Bioassessment of the Effluents Discharged from Two Export Oriented Industrial Zones Located in Kelani River Basin, Sri Lanka Using Erythrocytic Responses of the Fish, Nile Tilapia (Oreochromis niloticus)(Springer US., 2017) Hemachandra, C.K.; Pathiratne, A.Complex effluents originating from diverse industrial processes in industrial zones could pose cytotoxic/genotoxic hazards to biota in the receiving ecosystems which cannot be revealed by conventional monitoring methods. This study assessed potential cytotoxicity/genotoxicity of treated effluents of two industrial zones which are discharged into Kelani river, Sri Lanka combining erythrocytic abnormality tests and comet assay of the tropical model fish, Nile tilapia. Exposure of fish to the effluents induced erythrocytic DNA damage and deformed erythrocytes with serrated membranes, vacuolations, nuclear buds and micronuclei showing cytotoxic/genotoxic hazards in all cases. Occasional exceedance of industrial effluent discharge regulatory limits was noted for color and lead which may have contributed to the observed cytotoxicity/genotoxicity of effluents. The results demonstrate that fish erythrocytic responses could be used as effective bioanalytical tools for cytotoxic/genotoxic hazard assessments of complex effluents of industrial zones for optimization of the waste treatment process in order to reduce biological impacts.Item Survival and cholinesterase activity of Asian common toad (Duttaphrynus melanostictus) tadpoles following short term exposure to a carbosulfan-based pesticide(Sri Lanka Association of Fisheries and Aquatic Resources., 2017) Samarakoon, H.M.T.R.; Pathiratne, A.Carbosulfan, a carbamate pesticide widely used in agriculture especially in the Asian region has received less attention in ecological impact assessments particularly to non-target amphibians. In this study, short term effects of a carbosulfan-based pesticide (Marshal®) on survival and cholinesterase (ChE) activity of tadpoles of Duttaphrynus melanostictus, a non-target amphibian in tropical Asia were evaluated. Based on the concentration-toxicity response patterns, estimated median lethal concentration (LC50) and median ChE inhibitory concentration (IC50) for 96 h were 24 and 2.1 mg/L carbosulfan respectively. For the ChE inhibition for 96 h, the lowest observable effect concentration and no observable effect concentrations of carbosulfan were 0.6 and 0.3 mg/L respectively. Upon transfer to pesticide-free water by 14 days, ChE activities of the tadpoles were restored to normal levels. Since the tadpoles exposed to 0.3 mg/L carbosulfan have not exhibited lethality, morphological deformities, abnormal behavior or statistically significant ChE depression, it is unlikely that the carbosulfan-based pesticide could induce neurotoxic effects for D. melanostictus tadpoles at the concentration of ≤ 0.3 mg/L of active ingredient under short term exposure.Item Cytogenotoxicity screening of source water, wastewater and treated water of drinking water treatment plants using two in vivo test systems: Allium cepa root based and Nile tilapia erythrocyte based tests(Pergamon., 2017) Hemachandra, C.K.; Pathiratne, A.Biological effect directed in vivo tests with model organisms are useful in assessing potential health risks associated with chemical contaminations in surface waters. This study examined the applicability of two in vivo test systems viz. plant, Allium cepa root based tests and fish, Oreochromis niloticus erythrocyte based tests for screening cytogenotoxic potential of raw source water, water treatment waste (effluents) and treated water of drinking water treatment plants (DWTPs) using two DWTPs associated with a major river in Sri Lanka. Measured physico-chemical parameters of the raw water, effluents and treated water samples complied with the respective Sri Lankan standards. In the in vivo tests, raw water induced statistically significant root growth retardation, mitodepression and chromosomal abnormalities in the root meristem of the plant and micronuclei/nuclear buds evolution and genetic damage (as reflected by comet scores) in the erythrocytes of the fish compared to the aged tap water controls signifying greater genotoxicity of the source water especially in the dry period. The effluents provoked relatively high cytogenotoxic effects on both test systems but the toxicity in most cases was considerably reduced to the raw water level with the effluent dilution (1:8). In vivo tests indicated reduction of cytogenotoxic potential in the tested drinking water samples. The results support the potential applications of practically feasible in vivo biological test systems such as A. cepa root based tests and the fish erythrocyte based tests as complementary tools for screening cytogenotoxicity potential of the source water and water treatment waste reaching downstream of aquatic ecosystems and for evaluating cytogenotoxicity eliminating efficacy of the DWTPs in different seasons in view of human and ecological safety.Item Combination of physico-chemical analysis, Allium cepa test system and Oreochromis niloticus erythrocyte based comet assay/nuclear abnormalities tests for cyto-genotoxicity assessments of treated effluents discharged from textile industries(Academic Press., 2016) Hemachandra, C.K.; Pathiratne, A.Bioassays for cyto-genotoxicity assessments are generally not required in current textile industry effluent discharge management regulations. The present study applied in vivo plant and fish based toxicity tests viz. Allium cepa test system and Oreochromis niloticus erythrocyte based comet assay and nuclear abnormalities tests in combination with physico-chemical analysis for assessing potential cytotoxic/genotoxic impacts of treated textile industry effluents reaching a major river (Kelani River) in Sri Lanka. Of the treated effluents tested from two textile industries, color in the Textile industry 1 effluents occasionally and color, biochemical oxygen demand and chemical oxygen demand in the Textile industry 2 effluents frequently exceeded the specified Sri Lankan tolerance limits for discharge of industrial effluents into inland surface waters. Exposure of A. cepa bulbs to 100% and 12.5% treated effluents from both industries resulted in statistically significant root growth retardation, mito-depression, and induction of chromosomal abnormalities in root meristematic cells in comparison to the dilution water in all cases demonstrating cyto-genotoxicity associated with the treated effluents. Exposure of O. niloticus to the 100% and 12.5% effluents, resulted in erythrocytic genetic damage as shown by elevated total comet scores and induction of nuclear abnormalities confirming the genotoxicity of the treated effluents even with 1:8 dilution. The results provide strong scientific evidence for the crucial necessity of incorporating cyto-genotoxicity impact assessment tools in textile industry effluent management regulations considering human health and ecological health of the receiving water course under chronic exposure.