Applied Biology and Biochemistry Conference Papers
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Browsing Applied Biology and Biochemistry Conference Papers by Author "Basopo, N."
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- ItemThe Effect Of Three Species Of Schistosomes On Hepatic Drug Metabolism In Male BALB/ Mice(Elsevier, 1990) Naik, Yogeshkumar S.; Basopo, N.Schistosomiasis is a parasitic disease that affects over 200 million people in the world. S.mansoni and S.haematobium are of medical importance while S.mattheei is primarily of veterinary concern. It is important to know the effect that the disease has on elimination of xenobiotics. The effect of S.mansoni infection on thiopental sleeping times and zoxazolamine paralysis times has previously been reported by other workers as well as by us. Similar work on S.mattheei and S.haematobium infected animals, however, has not been reported in the literature. The effect of S.mattheei and S.haematobium on thiopental sleeping times was therefore studied and compared to results obtained for animals infected with S.mansoni. Thiopental sleeping times and egg loads of infected animals are shown in Table 1. Although S.haematobium infected animals did not have detectable levels of parasite eggs in their livers at 8 weeks post-infection, significant numbers of eggs were detectable at 12 weeks post-infection. This is in agreement with the observed delayed maturation of S.haematobium schistosomulae in rodents as compared to S.mansoni or S.mattheei. The number of worm pairs in each group was as follows: S.mattheei 20-25, S.mansoni 8-10, and S.haematobium (both 8 and 12 weeks post infection) 3-10 pairs. The sleeping times of all infected animals were prolonged when compared to their respective controls. The reasons for this are not clear but it is likely that the parasite egg-induced granulomas as well as the physical obstruction to portal blood flow caused by migration of•worms from mesenteric to portal veins play a significant role. Data obtained in this laboratory on drug metabolism in vitro in S.mansoni infected animals indicate that the activity of hepatic drug metabolising enzymes is also altered, but generlllly only in animals that have developed parasite egg-induced granulomas in their livers.
- ItemEffects of chronic exposures of selected heavy metals on the glutathione S-transferase activity of freshwater snails Lymnaea natalensis in Zimbabwe(Taylor & Francis, 2019) Mnkandla, S.M.; Siwela, A.H.; Basopo, N.The effect of the heavy metals (cadmium, copper, mercury and lead) on snail glutathione S-transferase (GST) was investigated in 2015. Groups of Lymnaea natalensis snails were exposed to heavy metals for 28 days at concentrations reportedly found in the Mguza Dam. Water and food were changed daily. Samples were collected at days 1, 7, 14, 21 and 28 post exposure. Inhibition of GST activity, following cadmium exposures, ranged between 58 and 60%, with a decrease of 30% on day 28. When snails were exposed to copper, inhibition significantly decreased by 16%, 29%, 49% and 72% inhibition when tested on days 1, 7, 14 and 21, respectively. Inhibition on day 28 was 44%. Mercury exposures resulted in significant increases in GST inhibition, namely, 47%, 62% and 79% inhibition on days 1, 7 and 14, respectively. Inhibition on day 21 was 82%, whereas on day 28 it was significantly lower, at 29%. Concerning lead exposures, inhibition levels on day 1, 7 and 21 had mean inhibition of 60%. Inhibition on days 14 and 28 was significantly lower, with a mean inhibition of 30%. These results suggest that chronic exposures could inhibit GST activity for a certain period, after which inhibition is reduced, possibly as a result of adaptation.
- ItemEsterase Activity of Two Aquatic Snail Species Helisoma Duryi And Lymnaea Natalensis(2013-03-12) Nyathi, C.B.; Naik, Yogeshkumar S.; Basopo, N.Previous work has shown that inhibition of esterase activity is likely to be a useful parafrieter to develop as a biomarker of organophosphate pollutants. We have extended our preliminary study and have now tested for esterase activity with two new substrates (five in total) while measuring the esterase activity in a newly established colony of the aquatic snails Lymnaea natalensis and Helisoma duryi. Post mitochondrial fractions prepared from whole body homogenates were used to measure esterase activity with the following 5 substrates: p-nitrophenyl acetate ( PNPA), (-naphthyl acetate (ANA), phenyl acetate (pHA), carboxylic esterase activity and acetylthiocholine iodide (Ach!) and S-butyrylthiocholine iodide (BthI) cholinesterase activity. Our data shows that the carboxylic esterase (CbE) activity measured in our new stock of snails was decreased (depending on the substrate used a range from 30% to 50%) compared to values obtained previously. Since the cholinesterase (ChE) activity was measured for the first time in these two species a comparison could not be made. In general, the esterase activity was found to be slightly higher in H. duryi than in L.natalensis. The reasons for the altered activity in the new snail colony is not clear but nutrient and climatic factors are likely to be responsible.
- ItemIn Vitro Effects of Carbaryl and Dimethoate on Esterases of Lymnaea Natalensis.(2013-03-12) Basopo, N.; Naik, Yogeshkumar S.; Nyathi, C.B.Agrochemicals have adverse biochemical and physiological effects on organisms and can ultimately cause disturbances in ecosystems. It is therefore important that sensitive techniques are available to monitor their presence and persistence in the environment be monitored. We are pursuing the possibility of developing modified esterase activity in aquatic snails as a potential biomarker for the detection of organophosphate and carbamate pesticides in contaminated waters. We have previously reported that exposure in vivo of the aquatic snail Lymnaea natalensis to a number of organophosphorus and carbamate pesticides causes inhibition of esterase activity to varying degrees in a pesticide and esterase substrate specific manner. Here we report on the effects of two commonly used pesticides, dimethoate and carbaryl in vitro, on the esterase activity of an aquatic snail L. natalensis. Post mitochondrial fractions were prepared from adult L. natalensis bred in outdoor cement aquaria. Esterase activity was measured in the presence of various concentrations of dimethoate or carbaryl. Our results showed a non-linear, but dose dependent, inhibition of esterase activity with both pesticides using 5 different substrates which were used to differentiate (choline and non-choline) esterase activity. Esterase activity was reduced significantly, depending on the substrate used, in the presence of both dimethoate (11 "10 - 78'Yo) and carbaryl (l5'Yo-93"1o). Both dimethoate and carbaryl showed similar IC50 values but variations were noted depending on the substrate used to determine esterase activity. Dimethote was, however, the mor'e potent of the two pesticides as shown by the its lower IC50 values when compared to carbaryl. Our data suggests there is a potential for the use of esterase activity in L. natalensis as a biomarker of organophosphorus and carbamate pesticides
- ItemMolluscan Esterase Activity As a Biomarker of Aquatic Pollution Caused By Monocrotophos.(2013-03-12) Naik, Yogeshkumar S.; Basopo, N.; Nyathi, C.B.There are many analytical protocols for detecting levels of agrochemicals~inaquatic systems. Methods of analytical chemistry can provide information of the exact concentrations in water samples. However they do not provide information on the potentially harmful effects on the organisms in the aquatic environment as biological markers have been shown to. Biomarkers of environmental quality should be tested under field situations if they are to be accepted outside academic circles and become part of national policies in environmental monitoring programs. We have previously shown that exposure of Lymnaea natalensis to organophosphates caused dose and time dependent inhibition of esterase activity. Here we report on the effects of monocrotophos on esterase activity in L. natalensis under field simulated conditions.Juvenile snails reared outdoors were exposed to single dose (5, 12, 15, 20 and 25ppb) of monocrotophos dissolved in either Matopos (pristine) or Umguza (polluted)dam water for 1, 7 or 14 days. Water was not changed for the duration of exposure. Post mitochondrial supernatants of whole snail homogenates were used to measure esterase activity. Cholinesterase activity was measured using acetylcholine iodide while carboxylesterase activity was measured using a-naphthyl acetate and 4nitrophenyl acetate. Esterase activity was significantly reduced in a dose responsive manner for aIr substrates. The degree of inhibitioll. varied depen,ding on the water source. Our results also indicated a decrease with time in degree of inhibition of esterase activity, suggesting a recovery with time of the snails from pesticide poisoning. 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. Umguza dam water is highly contaminated with industrial effluents and therefore expected to have a higher microbial load and increased pesticide decomposition rate when compared to Matopos dam water, which is relatively pristine. Our results have shown that esterase activity is very sensitive to presence of organophosphates with inhibitions of up to 92 % observed within 24 hours of exposure. Altered esterase activity therefore has a potential use as a biomarker for detecting organophosphatepollution in water samples.
- ItemPollutant mixtures as stressors of selected enzyme activities of the aquatic snail Halisoma duryi(Academic Journals, 2014-07) Basopo, N.; Mumbamarwo, L. T; Mkandla, D; Naik, Yogeshkumar S.This study involves an investigation on the effects of a pesticide, metal and a detergent as individual and mixtures on esterase and antioxidant enzyme activity of the freshwater snail Helisoma duryi. Adult snails were exposed to sublethal concentrations of copper (5ug/L), industrial detergent, oxyfoam (15ug/L), carbaryl (25ug/L) as well as mixtures of these pollutants for 96hours. Carboxylesterase and cholinesterase activities were measured using 4-nitropheny/acetate and acetylthiocholine as substrates respectively. The activities of superoxide dismutase, catalase, glutathione perioxidase and glutathione S-transferase were also measured as indices of oxidative stress. Esterase activity was inhibited in snails exposed to carbaryl, copper or detergent. Mixtures of the different chemicals also caused inhibitions of esterase activity when compared to the controls. All the chemicals individually antioxidant enzyme activity alteration of enzyme activity in the mixture-exposed snails though the increase was less than sum of effects of individual pollutants. More studies on the effects of a wider range of pollutant mixtures on aquatic organisms are needed however, for the full appreciation of reactive interactions that take place in complex mixtures which ultimately affect the health of aquatic biota.
- ItemPotential Use of Esterases As Markers of Aquatic Pollution By Organophosphate and Carbamate Pesticides(2013-03-12) Naik, Yogeshkumar S.; Basopo, N.Potential Use of Esterases As Markers of Aquatic Pollution By Organophosphate and Carbamate Pesticides Pesticides are used to widely in agriculture in Southern Africa. Many of these pesticides fall into the category of either organochlorines, pyrethroids, organophosphates or carbamates. We have been interested in the possible use of esterase is as biomarkers of environmental water pollution. Amongst the compounds we have studied are dimethoate, pirirniphos, malathione and monocrotophos. We have studied the effects of these pesticides on the esterase of aquatic molluscan species such as Lymnaea natalensis and Helisoma duryi and Physa acuta. The esterases studied include choline and non-choline esterases and activity was measured using different substrates namely, a-naphthyl acetate, phenyl acetate, 4-nitrophenyl acetate, acetyl thiocholine and S-butyryl thiocholine. Our data indicates that there is a marked species difference in the response to these pesticides. In addition we have found that carbamate pesticides inhibit esterase activity to a lesser extent than do organophosphates and that this inhibition is time and dose dependent. In general esterase activity has been shown to be inhibited by as little as one ppm within eight hours of exposure. Our date supports the results of studies conducted elsewhere in freshwater, estuarine, as well as marine organisms that suggest inhibition of esterase activity in aquatic organisms is a potential biomarker of water pollution. A review of the literature will be provided in addition to data generated in our laboratory.
- ItemRecovery Of Choline And Non-Cholinesterase Activity Of The Freshwater Snail Lymnaea Natalensis Following Exposure To Six Pesticides(2013-03-12) Naik, Yogeshkumar S.; Basopo, N.; Nyathi, C.B.Organophosphates and carbamates are the most widely used insecticides mainly because they are readily biodegradable in the environment. We investigated the recovery of esterase activity of an aquatic snail L. natalensis following a 24-hour exposure to 6 different pest.icides. A third of the snails were sacrificed after 24 hours while another third was allowed to recover in clean water for 14 days and the remainder for 28 days. All pesticides caused significant inhibition of esterase activity. Aldicarb caused the highest inhibition in esterase activity 98 % while thiamethoxam caused the least 61 %. Esterase activity improved significantly in the recovery period and 14 days in the recovery period, aldicarb and thiamethoxam exposed snails had recovered to 57 % and 67 % of control. After 28 days of recovery, aldicarb exposed snails had only 62 % esterase activity in comparison to controls. The results show that even after 28 days of recovery, esterase activity was still reduced by up to 38 % depending on the pesticide, an indication that recovery of the snails depends on the pesticide. From the results we suggest that where pesticides need to be applied more than once, a time gap between applications should be allowed to enable non-target organisms in soil and aquatic systems to recover from effects of previous applications thereby ensuring the good health of non-target organisms.