Applied Biology and Biochemistry Publications

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An Assessment of the Extent of Bovine Milk Pollution by DDT used in Public Health in Zimbabwe
(Scientia Research Library, 2016) Basopo, N.; Brock, Gerome; Mnkandla, Sanele
Indoor residual spraying of dichlorodiphenyltrichloroethane (DDT) has been widely used in the control of malaria, and has been appreciated for its low cost and high effectiveness. Prolonged use, however, has adverse effects as DDT and its metabolites persist for long in the environment, resulting in human and animal contamination. Contamination in animals such as cattle may result from consuming contaminated water, feed and fodder. The aim of the study was to evaluate the extent of contamination of DDT and its metabolites in cow’s milk from five towns in Zimbabwe. Samples were collected from farms around Bulawayo, Chiredzi, Esigodini, Harare and Mutare with a total of n=24 samples. The pesticide residues were extracted using the quick, easy, cheap, rugged and safe (Quechers®) method and solid phase extraction and analysed using gas chromatography with electron capture detector. Total DDT was detected in all samples at levels higher than the maximum allowable residue limit. Harare and Mutare samples had the highest DDT levels of 0.38 μg/ml and 0.26 μg/ml respectively, as compared with samples from other regions (0.08-0.13 μg/ml). The DDT metabolite residues,1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) and 1,1-dichloro- 2,2-bis(p-dichlorodiphenyl)ethylene (DDE), were also detected at varying levels in the samples. The results show the presence of DDT and its metabolite contaminants in bovine milk, posing a serious health risk to consumers. Alternatives to DDT may therefore need to be employed in the control of the malaria vector.
Carbaryl and Dimethoate Induced Alterations of the Antioxidant Defense System in Two Freshwater Pulmonate Snails Helisoma Duryi and Lymnaea Natalensis
(Scholars Research Library, 2016) Basopo, N.; Naik, Yogeshkumar S.
Organophosphates and carbamates are extensively used to increase the quality and quantity of field crops. These pesticides may indirectly enter water bodies where they affect aquatic organisms. Once absorbed by aquatic organisms the pesticides are metabolised and normal metabolic processes may produce reactive oxygen species that have adverse effects on the aquatic organisms. The effects of exposure to carbaryl and dimethoate pesticides on antioxidant enzymes of two freshwater snail species Helisoma duryi and Lymanea natalensis were evaluated. Groups of snails were exposed to 25 ppb of carbaryl and/or dimethoate for 72 hours. After the exposure duration they were then analysed for their effects on the oxidative defense systems of the snails. Increased thiobarbituric acid reactive substances levels and activities of catalase, superoxide dismutase, glutathione peroxidase and glutathione S-transferase in both snail species were observed, probably as a means of combating oxidative stress due to pesticide poisoning. Increased lipid peroxidation, coupled with altered levels of oxygen free radical scavenging enzymes in snail homogenates are discussed in relation to oxidative stress.
Effects of Industrial Effluent on Aquatic Organisms: A Study Using Zebra Fish (Danio Rerio) as a Model Of Evaluation
(African Journal of Science and Research, 2016-09-24) Mnkandla, Siphile; Ndebele, Donald; Teta, Charles; Basopo, N.
Industrial and municipal wastewaters are among the major contributors of chemical pollutants that enter aquatic bodies and affect aquatic biota, accounting for several thousand types of chemicals released into the environment. We exposed adult zebrafish (Danio rerio) to 3 dilutions of effluent (0.1 %, 0.5% and 1.0%)v/v and tap water (control) for 14 days to assess potential effects of industrial effluent on aquatic vertebrates. Antioxidant enzyme activities namely; superoxide dismutase, catalase, glutathione S-transferase and glutathione peroxidase were determined to evaluate oxidative stress effects in effluent exposed fish. The endocrine disrupting capability of the effluent was also investigated using vitellogenin assay. The results showed highest enzymatic antioxidant activity in fish exposed to the lowest industrial effluent concentration of 0.01% and increasing industrial effluent concentration reduced the antioxidant enzyme activity in exposed fish. A significant vitellogenin induction was observed in male fish that were exposed to the 0.01%, 0.1 %, 0.5% and 1.0% effluent concentrations compared the control. A non-linear dose response curve in vitellogenin induction was observed in male fish exposed to increasing effluent concentrations, indicating that complex interactive effects associated with high levels of chemicals in mixtures. The results showed that industrial effluent contain potent oxidative-stress-inducers and endocrine-disrupting-substances which affect the well-being of aquatic organisms.
The Effects of Sub Lethal Levels of Lead on Acetylcholinesterase Activity in the Rock Pigeon, (Columba Livia)
(Zimbabwe Journal of Science & Technology, 2017) Muusha, Yeukai; Mnkandla, Sanele; Basopo, N.
Lead is one of the most abundant heavy metals that has become widely distributed and mobilised in the environment. It exists in various forms which are bioavailable to many organisms including birds, causing physiological changes upon exposure. The aim of this study was to investigate the effects of sub lethal levels of lead on acetylcholinesterase activity in the Rock pigeon (Columba livia). Twelve free range and two pen reared (control) pigeons were collected from breeders around the city of Bulawayo and placed in separate cages. Six free range and one pen reared birds were exposed to 1.25 ppm lead acetate spiked feed and water for 72 hrs, whilst the remaining birds served as the unexposed control. Spiked feed and water were changed daily. Both the exposed and unexposed birds were sacrificed and the muscle, heart and liver tissues isolated and assayed for acetylcholinesterase activity. There was significant inhibition of enzyme activity in all tissue samples obtained from lead exposed free range birds when compared to their unexposed counterparts. In the lead exposed free range birds, muscle and liver acetylcholinesterase activity was below 0.005 μg/min/mg protein while that of the heart was in the 0.02-0.07 μg/min/mg protein range. Enzyme activity was greater than 0.1 μg/min/mg protein in the unexposed free range birds. Comparing the acetylcholinesterase activity of the lead exposed pen reared control, with that of the lead exposed free range birds, the latter demonstrated significant inhibition (p<0.05). The results therefore highlight the inhibitory effect of sub lethal levels of lead on acetylcholinesterase activity which could also be possibly enhanced by prior exposure to other environmental contaminants.
Inhibition of Esterases of the Freshwater Snails Helisoma duryi and Lymnaea natalensis by Mixtures of Pesticides.
(World Academic Publishing., 2012-02-02) Basopo, N.; Naik, Yogeshkumar S.
Pesticides indirectly reach aquatic reservoirs via aerial drifts and as runoffs where they affect aquatic organisms. Aquatic reservoirs receive different pesticides from the different fields which usually surround them. However, studies i investigating effects of pesticide mixtures on aquatic biota is limited. The effects of six pesticides and their mixtures on esterase activity of two freshwater snail species were investigated. Groups of snails were exposed to individual as well as mixtures of the pesticides for 96 hours before analysing for esterase activity. All pesticides inhibited esterase activity in exposed snails. Binary mixtures of pesticides caused additive or synergistic inhibitions of esterase activities when compared to effects of individual pesticides. The results indicated the importance of chemical interactions on the overall effects of pesticides on aquatic organisms
Pollutants, Snails, Oxidative-Stress, Organophosphates, Metals.
(Advances in Biological Chemistry, 2015-01) Basopo, N.
Aquatic reservoirs remain the ultimate sink of chemical pollutants emanating from anthropogenic activities such as agriculture, mining and industry. Freshwater biota undoubtedly is at risk from the adverse effects of these water pollutants and there is therefore, a need to monitor effects of these chemical pollutants in order to safeguard the health of aquatic biota. We investigated the oxidative stress effects of chlorpyrifos and lead on the freshwater snail Helisoma duryi to assess the potential of using this enzyme system as a biondicator of exposure to environmental pollutants. Groups of snails were exposed to 5 ppb lead acetate and 25 ppb chlorpyrifos for 7 days after which half of the snails were sacrificed and the other half were allowed to recover in clean water and sacrificed after another 7 days. Post mitochondrial fractions were used to measure the activities of the following antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and diphosphotriphosphodiaphorase. Both pollutants enhanced the activities of all the antioxidant enzymes suggesting a defensive mechanism by the snail to combat the oxidative stress due to the organophosphate chlopryrifos and metal pollutant lead. There was a significant recovery of the antioxidant defense system of the snails allowed to recover in clean water shown by the reduced alteration of the antioxidant enzyme activities of the snails allowed to recover for 7 days. This suggests the need to minimize exposure of aquatic biota to chemical pollutants and remediate the polluted water reservoirs in order to safeguard the health of aquatic life.
Thionphosphate Inhibition Of Esterase Activity In Freshwater Snail Hellsoma Duryi
(2013-03-14) Basopo, N.; Naik, Yogeshkumar S.; Nyathi, C.B.
Organophosphorus insecticides (OP's) are among the most commonly used pesticides in most African countries. These compounds are esters, amides or thiol derivatives of either phosphoric acid or thiophosphoric acids. The majority now in use such as azinphos methyl, chlorpyrifos, pirimiphos methyl and malathion contain the thiono moiety (=8) for (=0) on the phosphorus atom which increases the toxicity of the insecticide. There are six different chemical classes of OPls namely orthophosphates, thionphosphates, thiolphosphates, dithiophosphates, phosphonates and pyrophosphoramides (Hassall, 1990). When used in the vicinity of aquatic ecosystems the insecticides may enter in water bodies as a result of erosion and leaching in concentrations that I may affect non-target species such as fish and snails. Also the diversity in chemical structure of OP's that exist, results in variability in their toxicity. There is a need therefore to constantly monitor effects of these organic compounds on non-target organisms: The effects'of pirimiphos methyl, a thionphosphate on esterase activity in a freshwater snail Helisoma duryi was investigated with the aim of assessing its potential as a bioindicator of presence of OP's in water. Juvenile snails reared outdoors were exposed to pirimiphos methyl in either Matopos (pristi':le) dam water or Umguza (highly contaminated with industrial waste) dam water for 1, 7, or 14 days: Esterase activity determined in post mitochondrial supernatants was significantly depressed in',a dose dependent manner. Carboxylesterase activity measured using a-naphthyl acetate and'lpnitrophenyl acetate was reduced in the range (6-90 %) and (18-79 %) respectively while cholinesterase measured using acetylthiocholine iodide was inhibited in the range (19-85 %) depending on the water source. A decrease with time in degree of inhibition of esterase activity was also observed, suggesting a recovery with time of the snails from pesticide poisoning. This recovery of the snails was probably due to both natural and microbial decomposition of the pesticides with time. It's also possible that newly synthesized esterases replaced the inhibited ones. On comparing data from the two dams, higher inhibitions were observed in snails exposed to Matopos dam water than those exposed to Umguza dam water. Probably the higher microbial load in the contaminated Umguza dam resulted in increased pesticide decomposition and hence reduced inhibition of the snails in those waters whel} compared to those snails in Matopos, a pristine dam. Our results have shown that esterase activity altered by up to 90% is sensitive, to presence of pesticide pollutants and hence has a potential as a bio-indicator for detecting organophosphate pollution in water samples.
Toxicological Effects of Chlorpyrifos and Lead on the Aquatic Snail Helisoma duryi
(Scientific Research Publishing, 2015-10) Basopo, N.; Ngabaza, Thamsanqa
Aquatic reservoirs remain the ultimate sink of chemical pollutants emanating from anthropogenic activities such as agriculture, mining and industry. Freshwater biota undoubtedly is at risk from the adverse effects of these water pollutants and there is therefore, a need to monitor effects of these chemical pollutants in order to safeguard the health of aquatic biota. We investigated the oxidative stress effects of chlorpyrifos and lead on the freshwater snail Helisoma duryi to assess the potential of using this enzyme system as a biondicator of exposure to environmental pollu- tants. Groups of snails were exposed to 5 ppb lead acetate and 25 ppb chlorpyrifos for 7 days after which half of the snails were sacrificed and the other half were allowed to recover in clean water and sacrificed after another 7 days. Post mitochondrial fractions were used to measure the activi- ties of the following antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and diphosphotriphosphodiaphorase. Both pollutants enhanced the ac- tivities of all the antioxidant enzymes suggesting a defensive mechanism by the snail to combat the oxidative stress due to the organophosphate chlopryrifos and metal pollutant lead. There was a significant recovery of the antioxidant defense system of the snails allowed to recover in clean water shown by the reduced alteration of the antioxidant enzyme activities of the snails allowed to recover for 7 days. This suggests the need to minimize exposure of aquatic biota to chemical pol- lutants and remediate the polluted water reservoirs in order to safeguard the health of aquatic life.
Toxicological Effects of Differently Polluted Dam Waters Spiked with Pesticides on Freshwater Snails Lymnaea Natalensis
(Canadian Center of Science and Education, 2016) Mnkandla, Sanele; Basopo, N.; Tapfuma, Donald; Delfina, Majaya Rachel
Pesticides extensively used in agricultural fields to ensure high quality crop yields indirectly find their way to aquatic bodies where they affect aquatic biota. We investigated the effects of pesticides in different dam waters on esterase enzyme activity of the freshwater snail species Lymnaea natalensis. Groups of adult snails were exposed to 0.006 ppm chlorpyrifos and 0.003 ppm aldicarb in polluted water from Umguza dam and relatively pristine water from Hillside dam for 14 days. Carboxylesterase, acetylcholinesterase and arylesterase activities were measured. Both pesticides caused significant inhibition of esterase activity after the 14 day exposure period, with exposures to Umguza dam water showing higher inhibition as compared to exposures to Hillside dam water. Aldicarb and chlorpyrifos both showed a time-dependent inhibition of enzyme activity, the former causing a higher inhibitory effect as compared to the latter. Acetylcholinesterase was inhibited up to 80% following exposure to aldicarb while exposure to chlorpyrifos in Umguza water caused only 40% inhibition. Carboxylesterases were similarly inhibited with higher inhibition observed in snails exposed to Umguza dam water when compared to snails exposed to Hillside dam water, while arylesterases were inhibited in the range 80-90%, with an exception of chlorpyrifos spiked Hillside dam water which caused 45% inhibition. Contaminated Umguza dam water also appeared to enhance the effects of pesticides when compared to the relatively pristine Hillside dam water. Alteration of esterase activity can be used as an early warning signal indicating exposure to environmental pollutants. The results of this study therefore, highlight the adverse effects of pesticides on non-target aquatic organisms, evidenced by the inhibition of esterase activity.

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