Applied Biology and Biochemistry Conference Papers

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A study of scavenging poultry gastrointestinal and ecto-parasites in rural areas of Matebeleland Province, Zimbabwe.
(Asian Network for Scientific Information, 2010) Dube, S.; Zindi, P.; Mbanga, J.; Dube, C.
A study was carried out to determine endo and ecto-parasites in Matebeleland North and South from free range chickens (Gallus domesticus). Only adult chickens were selected for determination of parasite. For intestinal parasites microscopic studies of eggs and faecal egg counts were done using the salt floatation technique. The endo parasites encountered in the study were Tetrameres americana, Acuaria hamulosa, Ascaridia galli, Heterakis gallinarum, H. dispar, Allodapa suctoria, Capillaria annulate, Raillietina echinobothrida and R. tetragona. A commercially prepared insecticide constituted as follows (0.02% Tetamethrin, 0.03% pramethrin and 0.034% Imiprothrin) was applied for 2 seconds and feathers were then gentle unruffled so that ectoparasites could be counted and identified. Ecto parasites recorded in this study were Menopon gallinae, Menacanthus stramineus, Dermanyssus gallinae, Argas persicus, Ornithonyssus bursa, Cnemidocoptes mutans, Echidnophaga gallinacean, Gonocoites gallinae and Gonocoites hologester.
Activities of glutamate dehydrogenase and aspartate and alanine aminotransferases in freshwater snails Helisoma duryi and Lymnaea natalensis exposed to copper.
(Biomarkers, 2003) Masola, B.; Chibi, M.; Naik, Yogeshkumar S.; Kandere, E.; Zaranyika, M.F.
In this paper we investigate the potential of glutamate dehydrogenase (GDH) and aspartate and alanine aminotransferases (AST and ALT) as biomarkers of water pollution due to copper in the freshwater snails Helisoma duryi and Lymnaea natalensis. Snails were dosed with copper(II) ion concentrations of 0.01, 0.1 and 1 mg kg(-1) breeding water for a period of 96 h, after which those surviving were shelled. The copper content in the breeding water, in whole snail tissue and in the snail shells was determined at the end of the period of exposure. For enzyme determinations, whole snail tissue was first homogenized and fractionated by centrifugation at 500 g to remove the nuclei. The resulting supernatant was then centrifuged at 10,000 g to give a pellet fraction representing the mitochondrial fraction and a supernatant representing the cytosolic fraction. Copper was very toxic to both snail species at concentrations above 0.2 mg l(-1), with only 3% of the Helisoma and 12% of the Lymnaea surviving at concentrations of approximately 1 mg l(-1). The copper content in the shells and tissues of snails rose with increasing copper concentration in the breeding water, and was 2.1- to 4.9-fold in snails exposed to copper ion at a dose of 1 mg kg(-1) water compared with undosed snails. Similarly, the activities of GDH and AST rose by up to 4.7-fold in the homogenate and the mitochondrial and cytosolic fractions with increasing concentrations of copper. These activities, however, fell at copper concentrations of approximately 1 mg l(-1), which coincided with massive death of snails. Mitochondrial ALT disappeared at copper ion concentrations of approximately 0.2 mg l(-1) for Lymnaea and 1 mg l(-1) for Helisoma, possibly indicating mitochondrial degeneration. These results show that GDH, AST and ALT have the potential to be biomarkers of sublethal copper pollution in these two snail species, since their activities were significantly altered by low copper concentrations.
Aflatoxin carryover during large scale peanut butter production.
(Scientific Research Publishing, 2011) Andrew H, S.; Kudzayishe J, M.; Nozipo, N.
Peanut butter was monitored for aflatoxin contamination at different stages during its large-scale production starting from raw shelled peanuts up to the final product. Twenty five samples, weighing 2 kg each, were taken from each of the following stages: roasting at 160?C, blanching/de-skinning and grinding. The sub-samples were ground, thoroughly mixed and further reduced by the quartering technique until a 1 kg sub-sample was obtained. This was then analyzed for aflatoxins using reverse phase HPLC incorporating pre-column trifluoroacetic acid derivatization. The results showed a total aflatoxin percentage reduction of 51% after roasting, 27% after blanching/de-skinning followed by a further 11% after grinding to make peanut butter. This meant that there was a cumulative total reduction of 89% of aflatoxin concentration during the production process of peanut butter. These results show that there is a significant reduction of aflatoxin levels at the roasting and blanching stages in the process of producing peanut butter.
Altered Esterase Activity Due To Pesticide Exposure In The Aquatic Snail Physa Acuta.
(2013-03-14) Maredza, Alice; Naik, Yogeshkumar S.
The effect ofpesticides on the xenobiotic metabolising enzymes of the aquatic snail Physa acuta was studied. Adult snails reared in the laboratory were exposed daily for three days to the following pesticides: 2,4-dichlorophenoxyacetic acid, deltamethrin, endosulphan, malathion and pirimiphos-methyl. Cytosolic fractions prepared from the snails showed that pesticide exposure had no effect on the glutathione or glutathione dependent enzyme activities. General esterase activity using two different substrates was reduced significantly by exposure to the organophosphate pesticides malathion and pirimiphos. Exposure to the other pesticides did not cause any substantial changes in the esterases activities. The nature of this inhibition is not yet apparent. It is likely, however, that the changes are due to a competitive type inhibition by the pesticides for the active site of the enzyme.
Altered esterase activity due to pesticide exposure in the aquatic snail Physa acuta.
(2013-09-24) Maredza, Alice; Naik, Yogeshkumar S.
The effect of pesticides on the xenobiotic metabolising enzymes of the aquatic snail Physa acuta was studied. Adult snails reared in the laboratory were exposed daily for three days to the following pesticides: 2,4-dichlorophenoxyacetic acid, deltamethrin, endosulphan,malathion and pirimiphos-methyl, Cytosolic fractions prepared from the snails showed that pesticide exposure had no effect on the glutathione or glutathione dependent enzyme activities. General esterase activity using two different substrates was reduced significantly by exposure to the organophosphate pesticides malathion and pirimiphos. Exposure to the other pesticides did not cause any substantial changes in the esterases activities. The nature of this inhibition is not yet apparent. It is likely, however, that the changes are due to a competitive type inhibition by the pesticides for the active site of the enzyme.
Antioxidant enzyme profiles in a species of ornamental fish (koi)
(2013-03-11) Naik, Yogeshkumar S.
The aim of this work was to determine whether, and at what levels, antioxidant enzymes are expressed in the various organs of the koi. The activity of the antioxidant enzymes catalase (CAT), glutathione peroxidase (GPX), NAD(P)H: :' quinone oxidoreductase (NQOR) and malondialdehyde (MDA) content were determined in tissue homogenates of liver, kidney, pectoral muscle, gills, eggs, blood, heart and intestine. There was a marked variability (up to tenfold difference) in enzyme activity in the various organs, but much less individual variability ( - three fold difference). NQOR activity was highest in eggs (- 5.56(A/min/mg). Catalase activity also found heterogeneously in all organs had its highest activity in the liver ( - 5.02(A/min/mg). GPX (selenium dependent) activity was highest in the liver (5.14(A/min/mg). Thiobarbituric acid reactive substances (MDA) content, a measure of lipid peroxidation was, significantly low in all organs and tissues with an A535/mg of 0.00145(0.0027. The results suggest that antioxidant enzymes are expressed in most organs of the koi and that this species of fish is likely to be protected when exposed to compounds that either undergo redox cycling or that exerl a direct oxidative stress.
“Appropriate Technology for the 21st Century: Technological Innovation to Empower Africa”
(2014-11-25) Dube, Donatus; Parekh, Champaklal T.; Siangwata, Sherpherd; Nyathi, Makhosazana
Low-income earners in Zimbabwe’s rural areas currently depend, to a very large extent, on water from rivers, wells, dams and boreholes. Water from all these sources is contaminated in one form or the other by the anthropogenic as well as natural pollutants and in many cases is unsuitable for human consumption. Over the past decade, an increasing number of field-based studies have been undertaken to determine the success of point – of – use (POU) treatment measures in reducing waterborne diseases. However for poor communities in rural areas of Zimbabwe such interventions have remained largely ineffective due to availability and application challenges, lack of support, resistance due to cultural stigmas and mere ignorance. The aim of this research was to provide a simple POU solution to water quality problems in the rural communities of Zimbabwe. Thermally converted magnetite particle material with nanoporosity was used to construct rudimentary filters for use by villagers. Both laboratory and village scale tests were conducted. Results revealed that filters constructed using nano-porous magnetite material were very effective for microbiological and chemical pollution control in water and can be used successfully and sustainably by poor communities in the rural areas.
Assessing the impact of coal mining activities on soils and terrestrial organisms using land snail Achatina fulica as a bioindicator
(2022) Ndebele, D.
A lack of evaluation of soil quality in Zimbabwe's coal mining regions threatens the soil's ability to support biological productivity. Reports from the Environmental Management Agency of Zimbabwe and the Centre for Natural Resources Governance showed that the river (Deka) that flows through the study area was polluted. Pollutants in the Deka River were possibly emanating from land, but there was no scientific evidence. Hence it was important to evaluate pollution on land in the coal mining area. The biochemical response of the land snail Achatina fulica, exposed to soils collected from the coal mining area, was used to assess soil health. The level of selected heavy metals and polyaromatic hydrocarbon (PAH) levels were determined in soil samples obtained from 7 different sites at a coal mining area over a 2-year period (2018 to 2019). Soils obtained from the coal mining area were used to expose land snails acquired from a comparatively pure environment and acclimated to laboratory settings (for 1 year). The coal mining region's soils were determined to be mildly acidic (pH 5.53). Solubility of some metal elements increases when soils are acidic thus making such metals bioavailable and possibly increasing metal toxicity. The concentrations of heavy metals in soil samples from the coal mining area were significantly higher than in control soils (p < 0.05). The concentrations of zinc and cadmium were found to be above the World Health Organisation maximum permissible limits of 50 and 0.8 mg/kg respectively in the study period. Zinc and cadmium had mean concentrations of 164.40±81.82 and 0.97±0.27 mg/kg respectively. Results of regression analysis indicated that cadmium, lead and zinc were highly bioaccumulated with regression coefficients of 0.90, 0.94 and 0.95 respectively. Metallothionein induction in snail tissue often happen upon exposure of snails to certain metals such as cadmium. The highest levels of metallothioneins were observed in snail tissue exposed to soils with the highest concentration of heavy metal levels. The concentrations of naphthalene, acenaphthene, phenanthrene, anthracene, flouranthene, pyrene, benzo(k)fluoranthene, benzo(a)pyrene and indeno(1,2,3-c,d)pyrene in soils from the thermal power plant area were higher compared to soil from the control site (p < 0.05). High molecular weight (HMW) polycyclic aromatic hydrocarbons were predominant in soil samples from the coal mining area compared to low molecular weight polyaromatic hydrocarbons. High molecular weight polyaromatic hydrocarbons are carcinogenic and benzo(a)pyrene is the most potent. The thermal power plant area had the highest proportion of HMW polyaromatic hydrocarbons thus organisms around the area were likely to be at high risk of cancer and mutations. The sum of 14 polyaromatic hydrocarbons (Σ14 PAHs) at all sites was significantly higher than the 1000 µg/kg allowable in soil by United States Environmental Protection Agency. The ratio of anthracene to the sum of anthracene and phenanthrene was above 1 in soils from the disused coal processing area (Site C), active coal processing area (Site E) and thermal power plant area (Site F). This indicated that polyaromatic hydrocarbons in soils from Site C, E and F mostly emanated from wood, grass and coal combustion. There was a general increase in heavy metal and PAH levels from 2018 to 2019. This was probably because the study area is semi-arid hence leaching and runoff was minimal in soils from the coal mining area. Antioxidant enzyme (superoxide dismutase, catalase, glutathione peroxidase and NAD(P)H quinone reductase) and xenobiotic metabolising enzyme (glutathione S-transferase and ethoxyresorufin O-deethylase) activities were significantly increased in snails exposed to soils from the coal mining area compared to the control soil (p < 0.05). The high antioxidant enzyme activities showed that the snails were adapting to the effects of reactive oxygen species or experiencing oxidative stress. The highest xenobiotic metabolising enzyme activities were observed in snails exposed to soil from the coal tailing and power plant area. Persistent exposure (45 days) of land snails to contaminated soils markedly increased biomarker responses in land snails. Results showed ii that land snails are sensitive bioindicators and may be used to monitor pollution on land. Further more, results showed that combining biomarker measurements and chemical analysis can be a useful approach in evaluating the health of invertebrates in terrestrial ecosystems and the soil quality. The data obtained in this study can be included in soil ecotoxicological data and used in formulating soil quality management frameworks of the area.
Biomarkers of Environmental Pollution
(2013-03-14) Naik, Yogeshkumar S.
The threat to our environment due to human activity continues as the need for increased agricultural and industrial output continues. Agrochemicals currently used include pesticides such as organochlorines, organophosphates (OP's), neonicotinoids and pyrethroids. Industrial activity continues to generate an increasing diversity and volume of chemicals, such as PCB's and dioxins, that find their way into our natural and manmade water bodies. Metals such as lead, chromium and cadmium are either mined or are discharged as by-products of human activity. When used safely or disposed of properly these compounds are not always hazardous. However, their improper disposal or use poses a hazard to the health of humans, wildlife and the ecosystem as a whole. They are known to cause a variety of toxic effects such as genetic damage, organ toxicity and several physiological changes such as endocrine disruption. There is.a need to identify such toxic compounds and also to monitor their presence particularly in water bodies of Southern Africa where freshwater is scarce. Some of the methods, currently available to detect such toxins, include the measurement of parameters such as esterase activity (or its inhibition) for OP's, the extent of DNA damage (using the COMET assay) and induction/inhibition of detoxication enzymes (cytochrome P-450, glutathione S-transferase, antioxidant enzymes etc.) and induction of vitellogin synthesis (in fish). However, all these methods are not reliable or sufficiently sensitive. A summary of the data presented in the literature as well as that generated in our own laboratory will be presented.
Current Status of Mycotoxin Contamination of Food Commodities in Zimbabwe
(MDPI, 2018) Nleya, N.; Adetunji, M.C.; Mwanza, M.
Agricultural products, especially cereal grains, serve as staple foods in sub-Saharan Africa. However, climatic conditions in this region can lead to contamination of these commodities by moulds, with subsequent production of mycotoxins posing health risks to both humans and animals. There is limited documentation on the occurrence of mycotoxins in sub-Saharan African countries, leading to the exposure of their populations to a wide variety of mycotoxins through consumption of contaminated foods. This review aims at highlighting the current status of mycotoxin contamination of food products in Zimbabwe and recommended strategies of reducing this problem. Zimbabwe is one of the African countries with very little information with regards to mycotoxin contamination of its food commodities, both on the market and at household levels. Even though evidence of multitoxin occurrence in some food commodities such as maize and other staple foods exist, available published research focuses only on Aspergillus and Fusarium mycotoxins, namely aflatoxins, deoxynivalenol (DON), trichothecenes, fumonisins, and zearalenone (ZEA). Occurrence of mycotoxins in the food chain has been mainly associated with poor agricultural practices. Analysis of mycotoxins has been done mainly using chromatographic and immunological methods. Zimbabwe has adopted European standards, but the legislation is quite flexible, with testing for mycotoxin contamination in food commodities being done voluntarily or upon request. Therefore, the country needs to tighten its legislation as well as adopt stricter standards that will improve the food safety and security of the masses.
Differential Effects Of Some Quinoline Antimalarial Drugs On Rat Antioxidant Enzyme Activities
(2013-03-12) Naik, Yogeshkumar S.; Magwere, Tapiwanashe; Hasler, Julia A.
Quinoline-based antimalarial drugs have played a crucial role in the fight against malaria for decades. However, with the resurgence in drug tolerance among malaria parasites worldwide. The onus is on drug designers to synthesize more effective and less toxic drugs. In this study we sought to determine the effects of quinine, and the synthetic quinolines primaquine and chloroquine, on antioxidant enzymes so as to gain a better understanding of their effects on various enzyme systems which might be of value in the development of new, safe and more effective drugs. We used the Sprague-Dawley rat as a model to study the effects of these drugs on various hepatic and renal antioxidant enzymes. Our results show that primaquine administration increased the activities of some antioxidant enzymes (superoxide dismutase, glutathione peroxidase, and catalase), whereas chloroquine increased the activity of only superoxide dismutase while decreasing that of glutathione peroxidase and catalase. These results indicate a predisposition of the organs towards oxidative damage as evidenced by increases in parameters of lipid peroxidation in the same organs. Unlike the two synthetic drugs, however, quinine did not appear to cause any significant alterations in the activities of the antioxidant enzymes and neither did it cause any oxidative damage in rat organs. From these results, we conclude that since quinoline is still an effective drug against some chloroquine-resistant strains of malaria,the renewed interest in quinoline drugs should aim to design and synthesize quinine analogues which are less toxic and have enhanced antimalarial activity.
Effect Of Cadmium On The Activltes Of Glutamate Dehydrogemase, Alanine And Aspartate Aminotransferase In Fresh Water Snails, Helisoma Duryi And Lymnea Natalensis
(2013-03-14) Naik, Yogeshkumar S.; Masola, B.; Chibi, M.; Kandere, E.; Zaranyika, M.F.
Snails are known to accumulate metal ion pollutants in their tissues this being attributed to induction of metal binding proteins (Petering and Fowler. 1986). A consequence of the presence of pollutants in water inhabited by aquatic organisms may be the induction of enzymes required to metabolise or degrade the pollutants in such organisms. Other enzymes may also be induced in response to toxic effects of these pollutants on metabolic pathways in which these enzymes are involved. We are investigating the potential use of key enzymes of amino acid metabolism as markers of pollution due to metal ions in fresh water snails. Helisoma dllryi and Lnnl1ea natalensis. Experimental snails were drawn from concrete breeding tanks where they were regularly fed on lettuce. The snails were exposed for 96 hours to 0.0 1. 0.1 and I ppm concentrations of cadmium ion as a chloride salt. After exposure. snails were shelled excluding any dead snails. The tissue was homogenised and centrifuged at 500 x g for 10 minutes at 4PC to pellet nuclei and unbroken cells. The post nuclear supernatant was centrifuged at 10 000 x g for 10 minutes at 4uC. After suspension of the resulting pellet in buffer. both the pellet fraction ("mitochondria'" fraction) and the supernatant (cytosolic fraction) were aliquoted and stored at -82uC. The samples \vere assayed for the activities of glutamate dehydrogenase. and aspartate and alanine aminotransferases. The concentration of cadmium in breeding waters and in shells and tissues (not homogenised) was also determined. The concentration of cadmium in tissues rose with increasing concentTation the metal ion in breeding waters. In the absence of Cd added i.e. 0.03 and 0.02 1lg./ml Cd concentration in the breeding waters of Helisoma and Ll'lIlI1t!a respectively. the concentration of Cd was 0.08Ilg/g. in Helisvma and Ln7lnea tissues. This concentration rose to 0.47 and 0.37 Ilg/g. at I ppm added Cd for Helisoma and L.1'ml1ea respectively. showing 5.9 and 4.6 fold increases over initial concentration. Cadmium was also found to accumulate in shells of the two snail species. In general the activities of glutamate dehydrogenase (GDH). aspartate and alanine aminotransferases (AST and ALT) increased with concentration of cadmium but then decreased at Ippm added metal for GDH and AST. and at 0.1 ppm for ALT. In both snails consistent changes in GDH activity were seen in the homogenate and 10 000 x g pellet. At 0.1 ppm added cadmium the increased activity of GDH in the 10 000 x g pellet was 2.5 and 3.6 fold over initial activities for Helisol11a and Ll'Il1l1ea respectively. AST however showed consistent changes in the homogenates and 10 000 x g supernatants for both snails. At 0.1 ppm added cadmium the increased activity of AST in the 10 000 x g sup ematant was 3.4 and 1.8 over initial activities for Helisol11o and (1'IIlI1ea respectively. ALT also showed a similar pattern of activity change in the homogenate and 10 000 x g supernatant although decrease in activity staned much earlier at 0.1 ppm added metal. In the 10 000 x g pellets ALT activity progressively declined froin the initial values to reach 3-t°'0 and 43% of these values at I ppm added Cd for Helisol11a and (Hl/l1ea respectively. Since alanine and aspanate aminotransferases are known to be dually localised in the mitochondria and cy10so1 in a number of species. a possibility that enzyme could have redistributed due to organelle damage is unlikely in view of the low initial activities in the pellets. Funher the increase in enzyme activit. with metal ion concentration also occurred in the homogenates. The increases in enzyme activities were therefore likely to be due to induction of enzymes. Homogenate enzyme activities as well as those of pellet GDH and ALT. and supernatant AST could be sensitive indicators of Cd pollution
The Effect of Schistosoma Mansoni Infection on the Hepatic Drug Metabolizing Enzymes of Mice and Hamsters
(South African Journal of Science, 1998) Naik, Yogeshkumar S.; Hasler, Julia A.
Discusses the effect of schistosome infection on hepatic drug metabolizing enzymes. Examples of drug metabolizing enzymes; Effect of liver disease of drug metabolism; Alterations in enzyme activity caused by infection; Perturbations in hepatic drug metabolizing enzyme activity with S. mansoni infection.
The 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.
Effects 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.
Effects Of Exposure To Lead And Zinc On Antioxidant Enzyme Activity In Lymnaea Natalensis And Helisoma Duryi.
(2013-03-14) Masola, B.; Zaranyika, M.F.; Naik, Yogeshkumar S.
Metals such as Zinc (Zn) are is found in high concentrations in mine drainage, while lead, as tetra-ethyl lead in petrol, causes contamination of water, soil and air can lead to severe health consequences. Zinc has been shown to reduce the efficiency of oxygen transport across the gill membrane of fish, as well as the respiration and ammonia excretion rates of freshwater shrimp. Molluscs have been shown to accumulate a wide variety of pollutants and have, in some instances, proposed as indicators of environmental pollution by metals. The effect of lead (Pb) and Zn on the antioxidant enzymes (AOE's) of two aquatic snail species, namely Lymnaea natalensis and Helisoma duryi was studied with a view to developing a biomarker of freshwater metal pollution. Adult snails reared in the laboratory were exposed daily for three days to 0.01 ppm, 0.1 ppm and 1.0 ppm of either Pb or Zn S-9 fractions were prepared form whole snails. The S-9 fractions were used to measure the activity of AOE's such as DT-diaphorase, catalase and glutathione-S-transferase as well as reduced glutathione (GSH) and the product of lipid peroxidation, malondialdehyde (MDA). Lead exposure tended to increase enzymatic activity several fold. Significant changes were observed after exposure to 0.01 ppm and 0.1 ppm in L. natalensis. Zinc also increased activity of the enzymes but to a lesser extent. Levels of markers of oxidative stress, MDA and glutathione GSH were also altered, with MDA generally decreased in L. natalensis. In H duryimetal exposure resulted in an increased GSH levels when exposed to 0.1 ppm and 1.0 ppm of Pb as well as by all three concentrations of Zn but not in a dose dependent manner. In H duryi, but not L. natalensis metal exposure resulted in an increased (up to 75'7'0) MDA level. Our data suggest that antioxidant status, as a result of exposure to heavy metals in aquatic snails metals is not altered in a dose dependent or manner and is also species specific. Thus, the alterations in AOE's using either L. natalensisor H duryi, are not sufficiently reliable to develop a biomarker of heavy metal pollution in aquatic systems.
Esterase 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.
Esterases And Antioxidant Enzymes Of The Cotton Pests Helicovepa Armigera And Diparopsis Castanea
(2013-03-14) Naik, Yogeshkumar S.; Chingwena, G.; Giga, D.P.
Helicoverpa armigera and Diparopsis castanea are pests of economic importance in a number of crops, such as cotton, in Zimbabwe. The excessive use of insecticides such as organophosphates and pyrethroids, in the control of H. armigera has subjected it to high selection pressure. Many detoxifying enzymes of insects are thought to be responsible for insecticide resistance. The enzymes include the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), OTdiaphorase (OTO) as well as the glutathione S-transferases (GST) and esterases (EST). This study was aimed at measuring these enzyme activities in H. armigera collected from two geographical sites in Zimbabwe. The effect of diet (natural vs artificial) and age (instar) on the activities was also determined. A comparison was also made between the enzyme activities in H. armigera and O. castanea in samples collected from the same geographical area. Whole insects were homogenised in buffer and the homogenate was centrifuged at 15,000 x g and the supernatant was used to measure enzyme activity. Esterase activity was measured using three different substrates to differentiate aryl (phenyl acetate) and carboxylesterase (alphanaphthyl acetate and 4-nitrophenyl acetate) activity. Neither H. armigera diet nor geographical location produced any significant change in SOD, CAT, OTO or GST activities. Diet and geographical location did, however, produce a difference in the esterase activities depending on the substrate used. Age did not affect SOD, CAT, OTD and GST activities. Esterase activity varied with age and the 3rd and 5th instars showed generally lower activity than the 4th instar. When 3rd and 4th instars of red bollworm Oiparopsis castanea and H. annigera were compared,the SOD, CAT and OTO activities again showed little differences while the GST activity washigher in H. arnligera than O. castanea. The esterase activity using all three substrates was also found to be higher in H. annigera. Thus, in general, antioxidant enzyme activity did not vary significantly while esterase activity varied with diet and age and was species dependent.Our data suggests that there is likely to be an age and species dependent susceptibility to organophosphate pesticides for H.annigera and D.castanea.
Evaluation of test-kits for the detection of Escherichia coli O157 in raw meats and cattle faeces
(2012) Nyati, H.; Heuvelink, A.; Van Heerwaarden, C.; Zwartkruis, A.
Escherichia coli O157 detection limits in artificially contaminated beef and cattle faeces samples were determined using Dynabeads anti E. coli O157 immunomagnetic beads, VIDAS-UP, VIDAS-ICE, and real-time PCR (GeneDisc and LightCycler) systems. Dynabeads anti-E. coli O157 immunomagnetic separation (IMS) and the GeneDisc cycler were the most sensitive methods, and could detect an initial 1 CFU in 25g beef samples after 6h of incubation in modified tryptone soya broth with novobiocin (mTSB+n) or buffered peptone water (BPW). The VIDAS-UP method could detect an initial 10 CFU, while VIDAS-ICE and the LightCycler methods could only detect an initial 100 CFU. Higher detection rates were achieved with 18 hour incubations, where an initial 1 CFU in a 25g sample could be detected with all five methods. For cattle faeces enrichments, Dynabeads anti-E. coli O157 IMS could detect an initial 1 CFU after a 6 h incubation in mTSB+n, while the VIDAS-UP and VIDAS-ICE methods could detect an initial 10 CFU and both PCR methods could only detect an initial 100 CFU. Detection rates were lower in BPW, compared to mTSB+n, with thresholds of 100 CFU for VIDAS-ICE, VIDAS-UP and GeneDisc methods, and >100 CFU for the LightCycler method.
Genotyping Human Papillomavirus in Women Attending Cervical Cancer Screening Clinic in Harare, Zimbabwe
(2023) Matuvhunye, T.; Dube-Mandishora, R.S.; Chin’ombe, N.; Chakafana, G.; Mbanga, J.; Zumbika, E.; Stray-Pedersen, B.
Aim: To determine the prevalence of human papillomavirus genotypes in women attending a cervical cancer screening VIAC (visual inspection with acetic acid) clinic. Study Design: Cross-sectional studyPlace and Duration of Study: VIAC clinic at Parirenyatwa Referral Hospital in Harare in Zimbabwe between February and April 2015. Methodology: Sexually active women were recruited and they provided their socio-demographic data and self-collected vaginal swabs. HIV status of the participants was determined. DNA was extracted from the swabs using the standard phenol-chloroform method. HPV DNA was detected using the standard consensus MY09/11-GP5+/GP6+ nested polymerase chain reaction. Amplicons were sequenced and sequences analyzed using bioinformatics tools to identify the HPV genotypes. Results: Sixty women were recruited. Their age ranged from 21-83 years, with a mean of 40.1 years. Most of the women were married and resided in the urban areas. Of the 60 participants, 50% (30/60) were HIV-positive. The prevalence of HPV genotypes in the study subjects was 56.7% (34/60). HPVs were most prevalent in women aged 30 years and below, and became less prevalent as the age increased. The predominant genotypes detected were HPV-16, -58, -52, -45, 18, -33, -51, -6, -81, -11, -70, -62, -32 and -40. Conclusion: A number of HPV genotypes were detected in half of women tested. There was no significance association between risk-factors (parity, level of education, residence, history of STI, contraceptive use and sexual debut) and HPV infection. The findings of this study showed that consensus nested PCR and DNA sequencing could be used to detect HPV genotypes in women in cervical cancer screening programs. Although this method is sensitive, it is inefficient at detecting multiple HPV infections.

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