Zoology

Now showing 1 - 10 of 21

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.
Effect of abate on fingerlings of Arbochromis mossambicus (Peters)
(Sri Lanka Association for the Advancement of Science, 1991) Ranasinghe, J.; Pathiratne, A.
Haematological changes associated with epizootic ulcerative syndrome in the Asian Cichlid fish, Etroplus suratensis
(Asian Fisheries Society, Manila, Philippines, 1998) Pathiratne, A.; Rajapaksha, W.
Effects of physicochemical parameters of pond water on the occurrence of white spot disease in Penaeus monodon cultured in the North Western province, Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 1999) Hettiarachci, M.; Pathiratne, A.; Somathilake, R.P.H.
Studies on the Epizootic Ulcerative Syndrome (EUS) affecting freshwater fish in Bellanwila-Attidiya wetlands, Sri Lanka
(Sri Lanka Association for Fisheries and Aquatic Resources, 1998) Jayasinghe, P.K.; Pathiratne, A.
Composition, abundance and distribution of aquatic Oligochaeta in Colombo (Beira) Lake
(Sri Lanka Association for Fisheries and Aquatic Resources, 1996) Weerasundara, G.A.; Pathiratne, A.; Costa, H.H.
Toxicity of Chlorpyrifos and Dimethoate to fingerlings of Nile Tilapia, Oreochromis niloticus: Cholinesterase inhibition
(Sri Lanka Association for Fisheries and Aquatic Resources, 1998) Pathiratne, A.; Athauda, P.
Comparison of xenobiotic metabolizing enzymes of Tilapia with those of other fish species and interspecies relationships between gene families
(Marine Environmental Research, 1996) Pathiratne, A.; George, S.G.
Baseline data for hepatic xenobiotic metabolizing biomarker enzyme activities were obtained for artificially reared tilapia Oreochromis niloticus, and were compared with those of the plaice (Pleuronectes platessa) and rainbow trout (Onchorynchus mykiss). Basal activities exhibited species variations with notably higher CYP1A and phenol UGT activities and lower GST activity in plaice than the freshwater species. Interspecies relationships between gene families determined by immunoblotting and substrate-activity profiles demonstrated the presence of homologous CYP1A and CYP3A enzymes in all three species, alpha class GSTs in plaice and trout, mu and pi class GSTs in trout and theta class GSTs in plaice and tilapia. CYP1A of tilapia was induced by 3-MC or PBO treatment, whilst CYP3A was induced by PCN treatment. Copyright © 1996 Published by Elsevier Ltd.
Toxicity of malathion to nile tilapia, Oreochromis niloticus and modulation by other environmental contaminants
(Aquatic Toxicology, 1998) Pathiratne, A.; George, S.G.
Deliberate or accidental contamination of ponds by widely utilised organophophorous (OP) insecticides such as malathion is a potential problem for aquaculture in tropical countries. The aim of the study was to investigate potential synergistic or protective effects of common environmental pollutants on malathion toxicity in the Nile tilapia (Oreochromis niloticus) and by correlation of acute toxicity (LC50) studies with biochemical parameters, identify potential enzyme systems involved in malathion toxicity. Tilapia were very sensitive to malathion (96h LC50 2ppm) and in vitro data indicated that malaoxon, formed by oxidation of malathion, was the effective toxicant. Exposure of fish to an environmentally relevant dose of the insecticide synergist and CYP inhibitor, piperonyl butoxide (PBO) markedly reduced both the sublethal and the acute toxicity of malathion by 2-fold. Correlation of toxicity data with inducer effects and biochemical analyses failed to provide any evidence for CYP1-, CYP2B- or CYP3A-mediated malathion activation or detoxication in this species, thus the effect of PBO could not be attributed to inhibition of these enzymes. Whilst interspecies comparisons implicate hepatic θ class GST and non-specific carboxylesterase in malathion detoxication there was no evidence for alterations in malathion toxicity to tilapia by inducers of these enzymes. Treatment of fish with concentrations of a prototypical polyaromatic hydrocarbon, or cadmium, exceeding those producing effects in field situations, did not alter malathion toxicity indicating a lack of interaction of other common classes of environmental pollutants with OP toxicity
Investigations on toxic, antifeedant and repellent properties of the defensive secretion of Coridiusjanus (Hemiptera: Pentatomidae) and a synthetic mixture of its major volatile constituents
(Journal of National Science Council of Sri Lanka, 1991) Pathiratne, A.; Gunawardene, N.E.; Liyanage, S. K. J.

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