• The Korean Journal of Zoology
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• v.31 no.3
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• pp.191-206
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• 1988

Chick embryos which have received a single injection of the organophosphate compound,malathion (0.1 mg, 0.5 mg, 1.0 mg or 2.0 mg in 0.05 ml of corn oil) via the yolk sac at certain times (2 daya, 4 days or 6 days after incubation) have been investigated. After 9 days of incubation, chick embryos were harvested to investigate the effects of malathion on the development of cerebrum morphologically and biochemically. The effects of simultaneous injection of malathion and nicotinamide were also compared. On ultrastructural examination, neurons in cerebral cortex showed to be inhibited in their differentiation by malathion; nuclear irregularity, swelling of endoplasmic reticulum, and cytoplasmic vacuoles were observed. On cytochemical study of acetylcholinesterase(AChE) by electron microscope, the positive reaction products of this enryme were localized at the membrane of nucleus and endoplasmic reticulum of neurons. Inhibition of AChE activty was severe in groups treated with relatively low doses, which was consistent with the results of spectrophotometric analysis. The activity of lactate dehydrogenase(LDH) of cerebrum in groups treated with malathion was higher than that of the control group. The nicotinamide adenine dinucleotide(NAD) content of chick embruo treated with malathioti decreased significantly, and nicotinamide coinjection raised the NAD level as compared with the control group, thus preventing malathion-induced momhological alteration. In conclusion, it is suggested that malathion changes the ultrastructure of differentiating neurons and alters some enzyme activities in chick embryo cerebrum, and the severity of which is consistently dose-or age-dependent.

• Applied Microscopy
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• v.18 no.1
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• pp.60-76
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• 1988

Chick embryos which have received a single injection of the organophosphate compound, malathion (0.1 mg/0.05 ml, 0.5 mg/0.05 ml, 1.0 mg/0.05 ml or 2.0 mg/0.05 ml) via the yolk sac at certain times (2 days, 4 days or 6 days after incubation) have been investigated. After 9 days of incubation, chick embryos were harvested to examine the effects of malathion on the ultrastructure and the acetylcholinesterase(AChE) activity of the developing spinal cord. The effects of simultaneous injection of malathion and nicotinamide were also compared. On ultrastructural findings, neurons in the ventral horn of spinal cord showed to be inhibited in their differentiation by malathion; nuclear irregularity, separation of nuclear membranes, reduction of ribosomal distribution, and cytoplasmic vacuoles were observed. In the younger embryos treated with relatively high doses of malathion, nucleus and cytoplasmic organelles of neurons were severely destroyed, and the neurons were shown to be necrotic. On cytochemical study of AChE by electron microscope, the positive reaction products of AChE were localized at the membranes of nucleus and endoplasmic reticulum of neurons. Inhibition of AChE activity was severe in groups treated with relatively low doses of malathion. Nicotinamide (5.0 mg/0.05 ml) alleviated malathion-induced morphological alterations. In conclusion, it is suggested that malathion changes the ultrastructure and reduces. AChE activity in differentiating neurons, and the severity of which is consistently dose- and age-dependent.

• Korean journal of applied entomology
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• v.14 no.2 s.23
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• pp.53-58
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• 1975

The local variabilities of resistance to Malathion and NAC (Sevin) were studied during 1973 with the strains of small brown planthopper (Laodelphax striatellus Fallen) collected from Jinjoo, Sunsan, Milyang, Kwangjoo and Iri districts of southern part of Korea. The susceptible lab strain used for this study has been reared successively in the laboratory without exposure to any insecticide since 1970. The insecticides were applied topically in acetone to the thoracic sternum of the adult insects. $LD_{50}$ values of Malathion to the insect were varied with the locality of the planthoppers. Relatively high levels of resistance to Malathion were observed in the strains of Jinjoo and Suntan; showing 27.7 times in female and 24.9 times in male for Jinjoo stram and 18.4 times in female and 13.8 times in male for Sunsan strain as compared with the susceptible lab strain, and in other strains of Milyang, Kwangjoo and Iri the levels of resistance to Malathion were still less than 5 times. However, there was no any specific difference among the strains in susceptibility to NAC. The malathion-resistant strain of the small brown planthopper seemed to be still localized in some regions of· Korea. The susceptibility of the planthoppers to Malathion was varied with the sex; $LD_{50}$ values based on the individual (ug/insect) were higher in female than in male, while the values based on the body weight (ug/g) conversely higher in male than in female.

• Applied Biological Chemistry
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• v.14 no.3
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• pp.229-235
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• 1971

Kwanok, Fujisaka #5, Paldal, and Suwon #82 as japonica type and IR-262 and CP-slo as indica type of rice seeds were selected for this experiment among varieties grown in Korea. Activities of crude enzymes extracted from germinating seeds of these varieties on malathion and p-nitrophenyl acetate as substrates, esterase zymograms with 1-naphthyl acetate as substrate, and some observations are summarized as follows: 1. Activities per unit volume of crude enzyme preparations on malathion were in the order of Kwanok>IR-262>Fujisaka #5>CP-slo>Paldal>Suwon #82. 2. Esterase zymograms on agar-gel electrophoretograms exhibited three to four bands two electrodes with little difference among varieties, nevertheless showing a wide and strongly-colored band toward cathode. Suwon #82 has a somewhat different pattern from others. 3. Enzyme activities per milligram protein with p-nitrophenyl acetate as substrate were in the order of CP-slo>IR-262>Paldal>Kwanok>Suwon #82>Fujisaka #5, indicating that activities of indica type are much stronger than those of japonica type, but not in agreement with results with malathion. 4. Malathion did not much inhibit the esterase activity at the concentration of 0.2PPM on electrophoretograms. 5. It is supposed that there is a complex esterase system hydrolyzing malathion and p-nitrophenyl acetate in germinating rice seeds.

• Applied Biological Chemistry
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• v.2
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• pp.45-52
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• 1961

The decomposition of malathion in dust for mulations prepared from four Korean tales as carriers during storage period has been studied. Amberlite CG-120, a cation exchange resin . which has higher cation exchange capacity than tales, was also used as a carrier in hope of finding out the effect of nagative charge upon the decomposition of malathion. Besides the original talc powders obtained directly from the mines, the hydrogen ion saturated forms were also used as carriers for comparisonal study. The saturated ions for the resin were hydrogen, sodium and magnesium. As the physical properties of the tales, colloid content, water adsorption capacity, PH, specific surface, phosphate fixing capacity and exchangeable canons were determined, and these properties were correlated with the amount of the decomposition. Following results were obtained from the experiment. 1. The malathion in the talc in dust was found to decompose around 10-15% ofthe total withina month. About 50% of the decom position that took place after a month was found to occur within a week. 2. The resin which has higher cation exchange capacity than the tales was highly effective in the decomposition of malathion compared with the tales. 3. In every case the saturation of the exchange complexes with hydrogen ion greatly accelerated the decomposition of malathion. 4. The most highly correlated physical properties with the decomposition were colloid content and specific surface of the tales. 5. The water adsorption and phosphate fixing capacities of the tales were found not to correlate with the amount of malathion decomposed. From the experimental results it was concluded that the active negative spots on the colloidal tales or the resin attract the electropositive phosphorus atom in a malathion molecule thereby inducing the decomposition easier. The presence of hydrogen ion nearby might cause a catalytic effect in the decomposition of malathion.

• Korean journal of applied entomology
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• v.2
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• pp.22-26
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• 1963

1) This experiment was planned to determine the biological effectiveness and persistence of malathion residues on the polished rice under the natural storage conditions in Korea from June to September in 1963). 2) Whole kernel rice was treated with malathion as a spray. The test insects(21 days old were exposed) for a period of 8 days at given day intervals, 3) The biological effcetiveness and persistence of malathirm residues on the polished rice was determined as the mortality of the rice weevils, Sithophilus oryzas L. 4) It was observed from Table 1 and Fig. 1 that 100 per cent mortality was resulted in at 3 days from treatment in all dosages used in this experiment. At :1':days after treatment, the dosages of 16ppm and 8ppm gave still 100 per cent mortality, but the dosages of 4 ppm and 2 ppm resulted in $85.8\pm3.70\;and\; 43.3\pm10.77 per cent mortalities, respectively. After 32 days from the treatment,the mortalities in all dosages used did not show any 100 per cent mortality, At. 107 days after treatment, there was no any difference in the mortality of weevils inall dosages used. 5). It was observed from Fig. 1 and Table 2 that the half-life values of malathion residues on the polished rice was 33 days at 2 ppn!, 54 days at 4 ppm, 73 days at 8 ppm, and 93days at 16ppm, respectively. 6). To get a satisfactory control of the rice weevile with the malathion-residues for more than 5 months under the natural storage conditions, it may be necessary to use higher dosages than those used in this experiment.

• Applied Biological Chemistry
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• v.7
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• pp.15-19
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• 1966

In order to investigate the stability of the major component of malathion E.C. product, dimethyl S-(1, 2-dicarboxyethoxyethyl) dithiophosphate, toward the quality of glasswares as container, the amount of extractable inorganic components, change of pH and decomposition of the major component of the product were examined during the storage in brown-colored bottles of 100 ml. volume from 3 different companies in comparison with that in a Pyrex flask. 1. Malathion E.C. product was put in three containers A,B and C, and any changes occurring in storage were analyzed at three intervals of 60, 120 and 240 days. 2. It was shown that the amounts of Si, Mg, K, Ca, and Na extracted during these periods of storage differed markedly depending on the qualify of container. Container A revealed ten times higher extraction of Na and Ca than container B and C in a 8-month period. 3. Three commercial containers revealed the shift of pH from 6.5 to alkaline reaction in the storage whereas the Pyrex flask did not show any detectable change. In particular, the pH in container A changed to 9.2 in 60 days and 9.9 in 240 days. 4. The decomposition of malathion was the greatest in container A which showed the decomposition of 7.37% in 240 days. On the other hand, 0.5% was decomposed in the Pyrex flask. 5. The decemposition of malathion had a high correlation with the change of pH of water· in the same container, $r^2$ being 0.899. From the above results, it is concluded that about 10% of malathion E.C. product is decomposed in a year due to the alkaline metallic salts extracted from the container when it is stored in glassware bottles of lower quality.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1050-1053
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• 2000

Biological evaluation of residual malathion after 168 hrs of single dipping exposure of White Leghorn hens to different concentrations (0, 0.5, 1.0 and 1.5%) of pesticides was investigated. Thirty-two male albino rats divided into four groups of eight each were kept on 20% isoproteinous diet prepared from the meat of these malathion dipped hens. After 30 days feeding trial, the rats were killed by decapitation. No significant change was found in erythrocytes. However, the triglyceride concentration in brain tissue was increased significantly (p<0.05) when dose level of pesticide was 1% in dipping solution. Similarly, malathion exposed poultry meat failed in altering any significant change in the pancreatic amylase and lipase activities of rats. This study concludes the virtual absence of toxic accumulation of pesticide in the meat of birds after 168 hrs of exposure in usual concentration range upto 1.5%.

• Journal of Environmental Health Sciences
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• v.5 no.1
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• pp.58-60
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• 1978

This experiment was carried out to determine the amount of organophosphorous pesticides accumulated in farmer's blood during the farming season. The Blood had been collected for about 5ml from farmer's, and extraction was purified on a Avicel/Darco G-Co (1:10) column and determined by Gas Chromatography using AFID supported on 2% EGA. The Gas chromatographic detection yielded recoveries from the blood of 88% for smithion 94% for malathion. The amount of average contamination shows 0.045ppm for smithion. 0.054ppm for malathion.

• Korean Journal of Environmental Agriculture
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• v.8 no.1
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• pp.47-54
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• 1989

This study was conducted to investigate insecticide toxicities to a honeybee, Apis cerana F. being raised in Korea and its detoxifying enzyme activities. In order to determine the appropriate usage of insecticides, median effective dose and detoxifying enzyme activities to seven insecticides were observed. Various detoxifying enzymes, including microsomal oxidases, glutathione S-transferases, esterases, and DDT-dehydrochlorinase were assayed in the midguts of adult worker bees as the enzyme source. Of the insecticides used, $LC_{50}$ value in DDT treatment was the highest as 19ppm, and that in EPN treatment was the lowest as 0.75ppm. Sublethal exposures of honeybees to various insecticides had some effects on microsomal enzyme activities. Aldrin epoxidase activity was inhibited by malathion and demeton S-methyl treatment. N-demethylase activity was induced by carbaryl treatment. Of the glutathione S-transferases, aryltransferase(DCNB conjugation) activity was significantly induced by diazinon, and moderately induced by malathion. Of the esterases, ${\alpha}-NA$ esterase activity was moderately inhibited by malathion and permethrin. Carboxylesterase and acetylcholinesterase activity were not affected by the sublethal exposure of honeybee to the insecticides. Sublethal exposure of honeybee to the insecticides had no effect on DDT- dehydrochlorinase activity, except carbaryl, malathion and demeton S-methyl were inhibited.