Purification and properties of cytoplasmic malate dehydrogenase from Taenia crassiceps (Zeder, 1800) cysticerci

Malate dehydrogenase (L-malate: NAD oxidoreductase, EC 1.1.1.37) from the cytoplasm of Taenia crassiceps cysticerci was purified and the basic kinetic parameters of this enzyme were determined. The pH optimum range of enzyme reaction was found to be very wide: 8.8-11.0 for malate oxidation and 6.0-8.5 for oxaloacetate reduction. KM values for oxaloacetate, malate, NAD, and NADH were 7.8.10(-5) M, 1.4.10(-4) M, 1.2.10(-4) M, and 6.10(-5) M, respectively. Malate dehydrogenase activity was inhibited by malate excess. Molecular weight of malate dehydrogenase was 70,800. A comparison of the data obtained with those from other organisms including vertebrates showed that the cytoplasmic malate dehydrogenase from T. crassiceps is almost identical with the enzymes from other sources in its kinetic and regulatory properties, as well as in its molecular weight.     

DDT and BHC residues in some body tissues of goats, buffalo, and chickens, Lucknow, India

Muscle, liver, brain, and abdominal body fat samples of goats, buffalo, and chickens, all common meat sources in India, were analyzed by gas-liquid chromatography (GLC) for residues of DDT and benzene hexachloride (BHC). A few samples of goat and buffalo bone marrow were also included. Relatively high residue levels were found in body fat and bone marrow compared with other tissues. DDT and BHC residue levels were highest in chicken body fat, averaging 4.157 ppm sigma DDT and 3.879 ppm BHC. DDT content was much higher in goat and buffalo bone marrow than in the corresponding body fat. DDT levels in brain samples were highest (0.138 ppm) in buffalo. p,p'-TDE levels were higher than p,p'-DDE levels in buffalo; overall DDT levels were lowest in goats. BHC residues were generally low in buffalo; alpha-BHC accounted for most BHC residues in brain tissues. Greater accumulations of DDT and BHC were found in leg muscles than in breast muscles of chickens.     

Electrophoretic analysis of gene-enzyme systems in Chabertia ovina

In Chaberia ovina species an electrophoretic study of 15 loci of the following enzymes has been conducted: glucose phosphate isomerase, mannose phosphate isomerase, glucose-6-phosphate dehydrogenase, glutamate-oxaloacetate transaminase, superoxide dismutase, isocitrate dehydrogenase, hexokinase, adenylate kinase, malate dehydrogenase, malic enzyme, carbonic anhydrase and 6-phosphogluconate dehydrogenase. The genetic variability has been relatively high, with 40% polymorphism values noted, an 0.10 mean heterozygosity observed and an 0.17 mean heterozygosity expected. The greater part of the allele frequencies were not in Hardy-Weinberg equilibrium.     

Glucose metabolism in hepatopancreas and gill of Lamellidens marginallis during methyl parathion toxicity

Changes in glucose metabolism were studied in hepatopancreas and gill of freshwater mussel, Lamellidens marginalis, exposed to a sublethal concentration (8 ppm) of methyl parathion. A slight decrease in glycogen and pyruvate and an increase in lactate levels were observed. An increase in phosphorylase and aldolase suggested increased formation of trioses during methyl parathion toxicity. The decrease in lactate dehydrogenase activity and increase in lactate content indicated reduced mobilization of pyruvate into the citric acid cycle. Glucose-6-phosphate dehydrogenase activity was increased, suggesting enhanced oxidation of glucose by the HMP shunt pathway. Citric acid cycle enzymes such as isocitrate, succinate, and malate dehydrogenases were found to be decreased, suggesting abnormality in mitochondrial oxidative metabolism as a consequence of methyl parathion toxicity. The decreased cytochrome c oxidase and Mg²⁺-ATPase, apart from citric acid cycle enzymes, indicated impaired energy synthesis as a result of reduced aerobic oxidation of glycose. The increase in acid and alkaline phosphatase activities suggested enhanced breakdown of phosphate to release energy in view of inhibition of the ATPase system during methyl parathion stress. The changes were more pronounced in hepatopancreas as compared to gill of mussel exposed to methyl parathion.     

Some hematological,biochemical, and enzymological parameters of a fresh-water teleost fish, Channa punctatus, exposed to sublethal concentrations of quinalphos

Alterations in the levels of hemoglobin, total plasma proteins, glucose, and lactic acid in the blood; glycogen and lactic acid content of liver and white skeletal muscle; and the activities of lactate dehydrogenase, pyruvate dehydrogenase, and succinate dehydrogenase in liver, kidney, intestine, brain, gills, and muscles were examined in the fresh-water snake-head fish, Channa punctatus, after exposure to a sublethal concentration (25 μg/liter) of quinalphos for 60 and 120 days. Hemoglobin, plasma protein, glucose, and lactic acid decreased in pesticide-exposed fish. The glycogen content of the liver and muscles increased but lactic acid decreased. Lactate dehydrogenase activity decreased in all six tissues. Pyruvate dehydrogenase activity of liver, kidney, gill, and muscle decreased, but the enzyme activity was elevated in intestine and brain. In intestine, succinate dehydrogenase activity was elevated, and in the remaining five tissues the enzyme activity was significantly reduced. The present study showed that formation of glycogen and its breakdown was impaired in the liver, and aerobic oxidation of nutrients was adversely affected in quinalphos-exposed fish.     

Effects of Melia azedarach on nutritional physiology and enzyme activities of the rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

Laboratory assays were done to evaluate the effect of Melia azedarach L. (Rutales: Meliaceae) seed extract on nutritional indices and gut enzymes acid phosphatases, alkaline phosphatases, adenosinetriphosphatases, and lactate dehydrogenase of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Larvae were fed a treated rice-leaf diet containing the seed extract and their midgut was used for enzyme determination. Laboratory experiments showed that the seed extract suppressed the larval activity of C. medinalis even at a low dose. Gross dietary utilization (efficiency of conversion of ingested and digested food) of RLF decreased after ingesting the treated rice-leaf diet. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined significantly. As compared to the control, consumption of the extract containing rice-leaf diet resulted in a 69% reduction of the acid phosphatases activity, a 71% reduction of the alkaline phosphatases activity, a 46% reduction of the adenosine triphosphatases activity, and a 52% inhibition of the lactate dehydrogenase activity.     

Seasonal Fluctuations in the Concentration of BHC Residues in Butter

Marked seasonal changes in the BHC content of butter in Northern Ireland are reported. Levels of alpha-BHC rise to a maximum of between 0.5 and 0.9 mg/kg on a fat basis in January and February, falling to between 0.02 and 0.04 mg/kg in late summer and early autumn. The use of veterinary preparations containing technical BHC for the control of lice infection in the winter months would appear to be responsible for such fluctuations. Maximum BHC contamination of milk in January and February probably arises by direct ingestion or skin absorption of externally applied BHC and subsequent transfer from the bloodstream to the milk fat. A later smaller contamination peak in the April/May period is probably due to mobilisation of BHC stored in the body fat of the animals during the first weeks after parturition.     

Dose-dependent sub-chronic toxicity of diethyl phthalate in female Swiss mice

The experiment was conducted to study the after effects of administering DEP at different doses to female Swiss mice for a period of 90 days. Group I mice were fed on normal diet and water ad libitum. Group II mice were maintained on normal diet mixed with corn oil at 8.25 mg/kg of the diet/day as oil control. Group III, IV and V mice were given diethyl phthalate dissolved in corn oil mixed with the diet at 10, 25 and 50 mg/kg of the diet/day, which is approximately equal to 1.25, 3.125 and 6.25 mg/kg body weight/day. A significant dose dependent increase was observed in serum acid phosphatase (ACP) whereas, serum and liver triglycerides levels showed a significant increase only in the high-dose treated group. Significant dose-dependent increase in serum aspartate and alanine aminotransferase (AST and ALT) and liver glycogen was observed. Serum lactate dehydrogenase (LDH) was significantly increased only in 25 and 50 ppm DEP-treated mice. Liver cholesterol was significantly increased in all the treated groups. Liver histology by light microscopy showed intracellular vacuolations in all the treated groups which was much more evident in the 25 and 50 ppm DEP-treated mice while hepatocellular degeneration and hypertrophy of the hepatocytes was evident in 50 ppm DEP-treated mice. Proliferation of mitochondria and peroxisomes was evident in the electron micrographs of the 10 ppm DEP-treated mice while 25 and 50 ppm DEP-treated mice showed increase in lipid droplets and severe mitochondrial proliferation.     

Effect of endosulfan in female rats growing on low- and high-protein cereal diet

Endosulfan (α,β-1,2,3,4,7,7-hexachlorobicyclo(2,2,1)-heptene-(2)-bis-hydroxymethylene(5,6)sulfite) fed daily 0.5 and 100 ppm in the diet proved significantly toxic to female rats (initial weight 40–50 g) growing on a low-protein (5%) diet as compared to those growing on a high-protein (24%) diet. The toxic symptoms which developed exclusively in low-protein-fed rats included growth retardation, low blood counts, low RNA and protein levels in liver, and high glutathione levels in liver and blood. However, no changes in the activities of liver RNase, blood glucose-6-phosphate dehydrogenase, and glutathione reductase were observed. Liver glucose-6-phosphatase activity increased significantly. Endosulfan induced an increased accumulation of perirenal adipose in rats raised both on low- and high-protein diets. Endosulfan elicited cumulative toxic manifestations as evident from the relative degree of toxicity caused by 0.5 ppm and 18 weeks feeding. α-Endosulfan, β-endosulfan, and endosulfan sulfate were recovered from adipose tissue, the recovery being higher in adipose tissue of rats raised on a low-protein diet.     

Fate of endosulfan in rats and toxicological considerations of apolar metabolites

[¹⁴C]Endosulfan, α or β isomers separately, was administered to rats as a single oral dose and as a dietary supplement for 14 days. No appreciable differences were observed in the fate of the two isomers. Five days after the single dose, 75% of the dose had been voided in the feces and 13% in the urine. Of the total radiocarbon consumed in the diet after 14 days, 56% had been eliminated in the feces and 8% in the urine. Bile collection studies showed that up to 47% of a single oral dose was eliminated from the liver via this route; enterohepatic circulation was not apparent. Maximum [¹⁴C]endosulfan equivalents in body tissue occurred in the kidney and liver, 3 and 1 ppm, respectively, after 14 days of feeding 5 ppm of endosulfan. Apolar metabolites in the excreta and/or tissues were a minor portion of the total residues and consisted of the sulfate, diol, α-hydroxy ether, lactone, and ether derivatives of endosulfan. The sulfate was slightly more toxic to mice than endosulfan, while the other products were less toxic. Neither endosulfan nor its metabolites were active in the Salmonella mutagenicity test. Endosulfan in the diet of rats for 28 days at 50 ppm did not induce liver oxidase enzymes, alter liver or kidney weights, or influence the rate of weight gain of the animals.     

Oxidative damage, biochemical and histopathological alterations in rats exposed to chlorpyrifos and the antioxidant role of zinc

The protective effects of zinc on liver and kidney injury induced by chlorpyrifos (CPF) were investigated in rats. Male and female rats were orally administered CPF at a dose of 6.75 mg kg⁻¹ body weight for 28 consecutive days. An additional CPF group received zinc (227 mg l⁻¹) in drinking water throughout the experimental duration. Two groups more served as controls. Administration of CPF resulted in a significant increase in serum lipid peroxidation (LPO) level, while induced significant decreases in the activities of plasma superoxide dismutase (SOD), glutathione-S-transferase (GST) and serum acetylcholinesterase (AChE) either in male or female rats. Similarly, a significant increase in the levels of various serum marker enzymes [e.g. aminotransferases (AST and ALT), lactate dehydrogenase (LDH) and gamma glutamyl transferase (GGT)] and increase the level of total protein, uric acid and creatinine. In contrast, co-administration of zinc to CPF-treated animals restored most of these biochemical parameters to within normal levels. In case of AChE, supplementation of zinc showed little alteration in the activity of this enzyme especially in male rats treated with CPF. CPF caused histopathological change in liver and kidneys of male and female rats. However, zinc administration to CPF-treated animals resulted in overall improvement in liver and kidneys damage, emphasizing its antioxidant role. In light of the available data, it can deduce that CPF-induced lipid peroxidation, oxidative stress, liver and kidneys damage in male and female rats, and conjunction supplementation of zinc has resulted in pronounced ameliorating effect.     

转cry1Ab和epsps基因玉米对斑马鱼生长和繁殖没有影响

为评估抗虫耐除草剂转基因玉米DBN9936对斑马鱼Danio rerio的饲用安全性,本研究将DBN9936及其非转基因对照玉米DBN9858以22%的比例添加到基础饲料中饲喂斑马鱼56d,检测转基因玉米饲料对斑马鱼体长、体质量和繁殖的影响,并使用Westernblot方法检测了外源Cry1Ab和EPSPS蛋白在斑马鱼肌肉、肝脏、肠道组织中的残留情况。结果显示,转基因玉米饲喂斑马鱼56 d后,转基因玉米组斑马鱼的体长、体质量和繁殖指标与非转基因玉米对照组相比没有显著性差异,斑马鱼不同组织样品中也没有检测到外源Cry1Ab和EPSPS蛋白。56 d饲喂结果表明转基因玉米DBN9936与DBN9858非转基因亲本玉米对斑马鱼具有同样的饲用安全性,本研究为转基因玉米的安全应用提供了科学数据支持。     

Metabolic differentiation of bloodstream forms of Trypanosoma brucei brucei into procyclic forms. Effect of hydroxyurea, arabinosyl adenine, and serum omission

Bloodforms of Trypanosoma brucei brucei STIB 247 taken from rats and containing more than 80 per cent short stumpy forms, differentiated in vitro to procyclic forms in medium SDM 79 (Brun and Sch?nenberger 1979), enriched with 3 mmol.dm-3 cis-aconitate. Cell division was abolished by the addition of hydroxyurea (200 micrograms.ml-1) or arabinosyl adenine (20 micrograms.ml-1 to the cultivation medium, or by the omission of serum from the medium. The ultrastructure of exponentially growing controls was rearranged within 24 h. The endogenous respiration and the respiration stimulated by proline, succinate, and 2-oxoglutarate were detectable within 12 h; after 48 h the respiration rates were comparable to those found in the established procyclic forms. After 12 h the respiration was inhibited by 200 mumol.dm-3 KCN, and by 20 mumol.dm-3 antimycin to the extent found in procyclic forms. Hydroxyurea did not significantly affect respiration. Activities of procyclic-stage enzyme markers malate dehydrogenase, threonine dehydrogenase, succinate: cytochrome c reductase, and NADH: cytochrome c reductase rose within 48 h of differentiation to values which were close to those found in established procyclic forms. The activity of glutamate dehydrogenase (NAD-specific), however, was only 1/3 of that in the procyclics, and no citrate synthase was detected in differentiating culture. Glycosomal malate dehydrogenase was detected after 6 h. In the presence of hydroxyurea or arabinosyl adenine, or in the absence of serum, respiration rates, marker enzyme activities, and glycosomal malate dehydrogenase developed to the extent comparable to the untreated controls. The results suggest that it is possible to separate the process of differentiation from cell proliferation. Cell division is not a necessary prerequisite of differentiation.     

Brugia malayi: status of host during different stages of infection

The status of glycogen, protein, lipid components, lipid peroxides and a few enzymes of energy metabolism was studied in liver of Mastomys natalensis during the development of Brugia malayi infection. Glycogen and lipid contents were decreased during the patent phase of infection while total protein was slightly altered in latent animals. Phospholipid and triglyceride contents declined at prepatent and patent phase of infection. The levels of lactate and malate dehydrogenases, as well as of adenosine triphosphatases (Na+K+, Mg2+, Ca2+), were significantly elevated and monoamine oxidase activity was decreased at patent phase of infection, while succinic dehydrogenase remained unaltered. The lipid peroxide formation was enhanced in liver during the development of filarial infection.     

Persistent sub-lethal chlorine exposure elicits the temperature induced stress responses in Cyprinus carpio early fingerlings

Thermal effluents discharged through cooling systems of nuclear power plants often contain chlorine (used to control bio-fouling), which may affect the metabolic status of fishes. In order to evaluate the hypothesis, we tested the effect of high temperature and a persistent sub-lethal chlorine exposure on stress responses in Cyprinus carpio advanced fingerlings. Fishes were acclimated to four different temperatures (26, 31, 33, and 36 °C) and maintained for 30 days in two different groups. Subsequently, one of the groups was exposed to persistent chlorine (0.1 mg L₋₁) for another 28 days and was compared with their respective temperature controls (without chlorine exposure). Sub-lethal doses of pollutants and increasing temperatures with in the tolerance range may not always register any morphological changes Therefore, we studied organ specific biochemical pathways viz. aspartate amino transferase, alanine amino transferase (enzymes of protein metabolism) in liver and muscle; fructose 1,6 diphosphatase (gluconeogenic pathway), in liver; pyruvate kinase, malate dehydrogenase, and lactate dehydrogenase (glycolytic pathway) in muscle; glucose-6-phosphate dehydrogenase (pentose phosphate pathway) in liver; alkaline phosphatase (phosphorus metabolism) in intestine, liver, and muscle; acetylcholine esterase (neurotransmitting enzyme) in brain, and adenosine triphosphate (for membrane transport) in gills at two different acclimation periods (14 and 28 days). The results indicate that C. carpio fingerlings demonstrated metabolic readjustments with increasing temperatures, in order to cope with energy demand of the cell. However, exposure to chlorine at higher temperatures affected protein metabolism, gluconeogenic pathway and subsequently glycolytic pathway, leading to an energy-limited condition. In addition, alteration of membrane transport and neurotransmission might be an early indication of cellular damage. Overall results indicate that persistent sub-lethal chlorine exposure elicits temperature induced stress response in C. carpio early fingerlings.     

Adrenalectomy and the adaptive liver response in mirex-treated rats

Mirex, an organochlorine compound, was administered as a single oral dose (100 mg/kg body wt) to both intact and adrenalectomized juvenile male Sprague-Dawley rats. Both mirex-treated intact and adrenalectomized animals (dosed 24 hr postsurgery) exhibited significant increases in liver weight to body weight ratios compared to controls. However, the liver weight to body weight ratios in mirex-treated intact animals were significantly greater than those observed in mirextreated adrenalectomized animals. Significant increases were observed in liver weight to body weight ratios in adrenalectomized animals treated with mirex 4 days after surgery. However, the 96-hr mortality in mirex-treated adrenalectomized animals increased from 20% (mirex dose given 1 day postadrenalectomy) to 56% (mirex dose given 4 days postadrenalectomy). Mirex treatment of intact and adrenalectomized animals had no significant effect upon either serum or hepatic activities of glutamic oxalacetic transminase, glutamic pyruvic transaminase, sorbitol dehydrogenase, or protein concentrations. Bromsulfophthalein clearance also was not affected by mirex treatment in adrenalectomized animals. Serum glucose concentrations were significantly decreased in both intact and adrenalectomized animals by mirex treatment. Daily corticosterone supplements to adrenalectomized animals restored liver hypertrophy and serum glucose concentrations to levels observed in mirex-treated intact animals. These results suggest that mirex-induced liver enlargement may be mediated by corticosterone.     

Bendiocarbamate induced alterations in selected parameters of rabbit homeostasis after experimental peroral administration

The aim of this work was to determinate the effect of carbamate insecticide bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-yl N-methylcarbamate) on selected parameters of rabbit homeostasis. Animals were divided into four groups (control C, and experimental groups E1, E2 and E3 according to days of administration 10, 15 and 25 days). Animals from experimental groups received bendiocarb per os in a dose 5 mg/kg of body weight per day. Significant increase of creatinine content in E3 group (the longest administration of bendiocarb), increase of aspartate aminotransferase (E1 and E3 against control group) and gamma glutamyl transferase (E3 against control group) and decrease of glutamate dehydrogenase (E1 against control group) inform about possible failure of liver and/or kidney caused by bendiocarb. Decrease of haemoglobin (significantly in E3 group against control group), mean corpuscular haemoglobin (MCH) concentration (in all experimental groups), platelet count (in all experimental groups) can signify defection in haemoplastic system.     

Toxicity of brodifacoum to the rock hyrax,Procavia capensis

Rock hyraxes,Procavia capensis (Mammalia: Hyracoidea), were fed 0.005% brodifacoum in apple bait for 20 and 48 h in no-choice laboratory experiments. Death of three out of five animals took place (11-15 days after the feeding) after the consumption of 7.0-7.9 mg a.i./kg body weight in the 20-h feeding and in four out of four animals death occurred (6-9 days after the feeding) following the consumption of 5.7-15.4 mg/kg in the 48-h feeding.     

Impact of phorate on malate dehydrogenases, lactate dehydrogenase and proteins of epigeic, anecic and endogeic earthworms

The effects of an organophosphate pesticide phorate on cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH), lactate dehydrogenase (LDH), supernatant and mitochondrial proteins of an epigeic (Perionyx sansibaricus), anecic (Lampito mauritii) and endogeic (Metaphire posthuma) earthworms were studied. The treatment of different concentrations (20, 40, 80 and 160 ppm) of phorate for 16 days gradually decreased the specific activities of cMDH, mMDH and LDH as well as cytoplasmic and mitochondrial protein contents. This showed the inhibitory effect of phorate on metabolic enzymes and proteins in tropical earthworms. The inhibition was dose- and time-dependent. The inhibitory response in mitochondrial enzyme (mMDH) and protein was somewhat earlier and more as compared to the inhibitory effect of phorate on cytoplasmic enzymes (cMDH, LDH) and protein. This indicates a greater interference of phorate in cellular respiration of earthworms. The phorate related decreases in enzyme and protein profiles were about 60% and 58% in P. sansibaricus, 54% and 49% in L. mauritii and 47% and 42% in M. posthuma, respectively. It reflects phorate-induced substantial decline in protein synthesis and aerobic and anaerobic capacity of earthworms. The maximum effect of phorate was on epigeic earthworm followed by anecic and endogeic species. The present findings suggest the differential sensitivity of different earthworm species in enzymatic and protein responses to phorate and the sensitivity was associated with the ecophysiological categories of earthworms.     

Isozyme analysis of Plasmopara halstedii using cellulose-acetate gel electrophoresis

Isozyme analysis by cellulose-acetate gel electrophoresis was used for the first time on Plasmopara halstedii , the causal agent of sunflower downy mildew. Forty-five isolates originating from sunflower, cocklebur and Helianthus  ×  laetiflorus were used, comprising 10 field isolates and 35 single-spore lines of an additional 30 field isolates representing 10 different virulence phenotypes. Sixteen isozyme systems were analysed, of which three, isocitrate dehydrogenase, malate dehydrogenase and phosphoglucomutase, resulted in clear, reproducible banding patterns and revealed some polymorphism among the isolates. Phosphoglucomutase differentiated two groups among the isolates collected from cultivated sunflower, while the other enzymes were polymorphic between isolates from the different hosts. Polymorphisms were not related to virulence phenotype.