Effect of fenvalerate on protein and amino acid contents and enzyme activities in the ostracod Chrissia halyi

The short-term effect of fenvalerate on some metabolites and enzymes of protein metabolism in the ostracod Chrissia halyi was studied. The ostracods were subjected to two different concentrations of fenvaierate and the alterations in total proteins, total free amino acids, transaminases i.e. aspartate amino transferase (AAT)/glutamate oxaloacetate transaminase (GOT) and alanine amino transferase (ALAT)/glutamate pyruvate transaminase (GPT) and glutamate dehydrogenase (GDH) after one and three days were noted. Total protein and free amino acid contents in the organisms were found to be depleted, whereas both the transaminases and GDH levels were elevated. The results indicate that exposure of C. halyi to fenvalerate leads to metabolic adaptations to suit the functional need of the animal.     

Sulfonylurea herbicides: Growth inhibition in soybean cell suspension cultures and in bacteria correlated with block in biosynthesis of valine,leucine, or isoleucine

The sulfonylurea herbicides chlorsulfuron (CS) and sulfometuron methyl (SM) inhibit the growth of soybean cells (Glycine max L. var. Amsoy 71) in suspension culture with 50% inhibition at 170 and 62 ppb, respectively, relative to the initial cell dry weight, and CS is not rapidly metabolized in these cultures. In Glycine max L. cv Merrill var. Mandarin, CS inhibits the growth by 50% at 4 ppm on the basis of initial cell dry weight. This inhibition is partially reversed by valine, leucine, or 2-ketoisovalerate, but not by pyruvate, isoleucine, or any other single amino acid. CS drastically reduces the content of free valine and leucine in soybean cells without significant effect on the amount of other free amino acids. Deoxyribonucleosides alleviate a portion of the CS growth inhibition in soybean cells in vivo, though CS and SM do not inhibit ribonucleoside diphosphate reductase in vitro. CS and SM are bacteriostats for Escherichia coli and Salmonella typhimurium in minimal growth medium. E. coli growth is retarded at CS concentrations (100–300 μg/ml) that inhibit RNA and protein synthesis but not DNA synthesis. CS growth inhibition in E. coli is enhanced by cysteine and valine and partially alleviated by isoleucine and the aromatic amino acids, but not by leucine. The sulfonylureas appear to act in soybean by blocking the synthesis of valine and leucine between pyruvate and 2-ketoisovalerate and in E. coli by inhibiting isoleucine biosynthesis.     

Mode of action of sodium sulfanilate for control of groundnut rust (Puccinia arachidis S.) and its toxicity to the host plant (Arachis hypogaea L.)

Protection of groundnut plants against leaf rust by sodium sulfanilate is reversed by both p-aminobenzoic acid and folic acid, indicating an antifungal action based on interference with folic acid biosynthesis. Folic acid is required for growth of the pathogen. However, protection may also be associated with induced disease resistence because amino acids, particularly aspartic acid and glycine, accumulated in the host plant while there was a reduction in content of threonine and proline. These conditions are possibly unfavorable for growth of the rust fungus and susceptibility of the host plant. Sodium sulfanilate causes phytotoxicity at high concentrations by reducing chlorophyll content. This phytotoxicity is reversed by addition of p-aminobenzoic acid.     

Multiple effects of a naturally occurring proline to threonine substitution within acetolactate synthase in two herbicide-resistant populations of Lactuca serriola

Two populations of Lactuca serriola L. with resistance to acetolactate synthase (ALS)-inhibiting herbicides were discovered in wheat fields at two locations more than 25 km apart in South Australia. Both resistant populations carried a single base change within a highly conserved coding region of the ALS gene that coded for a single amino acid modification within ALS. The modification of proline 197 to threonine resulted in an enzyme that was highly resistant (>200-fold) to inhibition by sulfonylurea herbicides and moderately resistant to triazolopyrimidine and imidazolinone herbicides. The herbicide-resistant ALS was also less sensitive to inhibition by the branched-chain amino acids valine and leucine. In addition, the resistant enzyme had a lower K_m for pyruvate. However, extractable ALS activity was similar between resistant and susceptible plants. The substitution of threonine for proline 197 within ALS has multiple impacts on ALS enzyme activity in L. serriola that may influence the frequency of this resistant allele in the environment.     

Physiological responses of corn (Zea mays) to AC 243,997 in combination with valine,leucine, and isoleucine

Various physiological processes were measured in corn after treatment with AC 243,997. Neutral sugar levels in leaves increased 39% over the control 24 hr after application of AC 243,997. Protein synthesis, measured by [¹⁴C]leucine and [¹⁴C]cystine incorporation, and lipid synthesis were not inhibited 24 hr after application of 150 μM of AC 243,997, while respiration and RNA synthesis were inhibited 32 and 15%, respectively. DNA synthesis was severely inhibited (70–90%) by 150 μM of the herbicide 24 hr after application. The inhibition of DNA synthesis by AC 243,997 did not begin until 5 to 7 hr after application. Although protein synthesis rates were apparently unaffected by AC 243,997, the level of the soluble proteins decreased 40% while free amino acid levels increased 32% 24 hr after application of the herbicide. An exogenous supply of valine, leucine, and isoleucine to corn prevented the inhibition of growth and reversed the inhibition of DNA synthesis caused by AC 243,997. All three amino acids at a concentration of 1 mM were needed to provide maximum protection. The results support the hypothesis that AC 243,997 kills plants by interfering with the biosynthesis of valine, leucine, and isoleucine.     

Intoxication effects of lindane (γ-BHC) on the activities of aspartate and alanine aminotransferases of Anabas testudineus (Bloch)

Two transaminases, viz., aspartate aminotransferase and alanine aminotransferase, in six tissues of Anabas testudineus (Bloch) exposed to 0.075 mg/liter (120 hr LC₀) and 0.59 mg/liter (24 hr LC₁₀₀) of lindane were studied. An increase in the transaminase activity levels was observed in all the tissues except liver and muscle. Elevations observed in the later periods of exposure were higher than those observed in the initial periods of exposure in all the tissues except liver which showed an inverse trend. The significance of the results is discussed.     

Nitrogen metabolism disorder in watermelon leaf caused by fusaric acid

The effect of fusaric acid (FA) on the activity of leaf nitrogen (N) metabolism enzymes in watermelon seedlings supplied with different N forms was studied. The results showed that FA inhibited nitrogen uptake and caused decreased leaf amide and protein but increased the content of ammonium and amino acids. When treated with FA the activities of enzymes in the pathway for the synthesis of amino acid in leaves (GS, GOGAT, and GDH) were decreased by 15–23%, 13–40%, and 71–86%, respectively. The activity of asparagine synthetase was decreased by 34–57%. The proteinase activity was initially increased by 37–125% at 12 h after treatment of FA but then subsequently decreased. The activity of glutamate-pyruvate aminotransferase was increased by 280–400%, though the activity of glutamate-oxaloacetate aminotransferase was decreased by 30–63%. It was suggested that FA inhibited the uptake of ammonium in seedlings and suppressed the activities of amino acid and amide synthases, while stimulating proteinase activity.A new pathogenic mechanism of watermelon infection by Fusarium spp. was found as FA caused the complete disorder and collapse of the host plant's nitrogen metabolism. This work provides a new insight into the progression of watermelon wilting caused by Fusarium oxysporum f.sp. niveum.     

Oxidative parameters of Rhamdia quelen in response to commercial herbicide containing clomazone and recovery pattern

In this study, fish Rhamdia quelen, were exposed to different concentrations of herbicide clomazone: 0.0 (control), 0.45 and 0.91 mg L⁻¹. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery period (8 days). Oxidative stress indicators such as thiobarbituric acid reactive substances (TBARS) levels and protein carbonyl content, as well as antioxidant defenses, such as catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), ascorbic acid and non-protein thiols levels were studied, using the liver, brain and muscle tissues. Herbicide exposure increased TBARS in muscle and in liver at higher concentration. In liver protein carbonylation increased and catalase activity did not change in fish exposed to herbicide. SOD enhanced in liver at concentration of 0.91 mg L⁻¹. GST, ascorbic acid and non-protein thiols levels increase at both concentrations. At the end of the recovery period the most of the parameters recovered whereas GST and ascorbic acid remain elevated. The present study demonstrates the occurrence of disorders in antioxidant parameters and importance in the assessment of the potential risk of herbicides as clomazone on fish species.     

Antifungal bioactivity of 6-bromo-4-ethoxyethylthio quinazoline

In order to create novel potent antifungal agents, the antifungal effects of 6-bromo-4-ethoxyethylthio quinazoline on plant pathogenic fungi were evaluated by mycelial growth rate method. The bioassay results showed that title compound possesses high antifungal activities on fungi with EC₅₀ values ranging from 17.47 to 70.79 μg/mL. The mechanism of action of 6-bromo-4-ethoxyethylthio quinazoline against fungi was studied in Gibberella zeae model. After treated with title compound at 100 μg/mL for 12 h, the mycelial reducing sugar, chitosan, soluble protein and pyruvate content, chitinase activity showed declining tendency.     

Role of phaseolotoxin production by Pseudomonas syringae pv. actinidiae in the formation of halo lesions of kiwifruit canker disease

Pseudomonas syringae pv. actinidiae, the causal bacterium of kiwifruit canker, induces the formation of chlorotic halo lesions on infected leaves and inhibits the growth of Escherichia coli. The inhibition ofE. coli growth was shown to be reversed by L -arginine or L -citrulline, but not by L -glutamine, suggesting that the pathogen produces a toxin similar to phaseolotoxin, which inhibits ornithine carbamoyltransferase. The toxin was purified from culture broth of P. syringae pv. actinidiae strain Kw11, and was shown by nuclear magnetic resonance to be identical to phaseolotoxin. Assays based on inhibition of E. coli growth and on amplification of a phaseolotoxin fatty acid desaturase gene (ptx) fragment revealed that, among the plant pathogenic bacteria examined, the production of phaseolotoxin is restricted to strains of P. syringae pv. phaseolicola and pv.actinidiae . A non-toxigenic mutant of strain Kw11 generated by disruption of the ptx gene induced the formation of necrotic lesions on kiwifruit leaves; however, the lesions were not surrounded by a chlorotic halo as were those induced by the parent strain. The growth rate of the non-toxigenic mutant in leaf tissue was similar to that of the parent strain. These results suggest that phaseolotoxin production contributes to the formation of chlorotic halo lesions in kiwifruit canker but is not required for multiplication of the pathogenic bacterium during infection.     

Toxic effects of novel organophosphorus insecticide (RPR-V) on certain biochemical parameters of euryhaline fish, Oreochromis mossambicus

The euryhaline fish, Oreochromis mossambicus was exposed to sub-lethal concentration (0.017 mg L⁻¹) of a novel phosphorothionate, 2-butenoic acid-3-(diethoxy phosphinothionyl) ethyl ester (RPR-V) for 30 days and allowed to recover for 7 days. Important biomarker enzymes were assayed in plasma, brain, gill, liver, kidney, and muscle during exposure tenures of day-3, -7, -15, -30, and also at 7 days (withdrawal) after stopping treatment. Acetylcholinesterase (AChE) activities of brain, gill, and muscle were strongly inhibited by 67, 75, and 66%, respectively, on day-30. Exposure (time) dependent increases in alanine aminotransferase (ALAT), and aspartate aminotransferase (ASAT), acid phosphatase (AcP), and alkaline phosphatase (AkP), activities in plasma and kidney; AcP and AkP activities in gill were noticed. However, significant decrease in ALAT, ASAT, AcP, and AkP activities in liver was observed. The depletion of glycogen was observed in liver, brain, and gill tissues, an indication of typical stress related response of the fish with pesticide. A significant increase in lactate dehydrogenase (LDH) activity in gill and brain was observed and decreased in liver and muscle, indicating tissue damage and muscular harm. Depletion of glutathione (GSH) was observed in the above tissues, there by enhancing the lipid peroxidation resulting in cell damage. The induction in hepatic glutathione-S-transferase (GST) levels indicates the protection against the toxicity of xenobiotic-induced lipid peroxidation. There was a significant recovery in all the above biochemical parameters, in all the tissues of fish after a recovery period of 7 days. These results revealed that RPR-V affects the intermediary metabolism of O. mossambicus and the increase of biomarker enzymes in plasma, might be due to the necrosis of liver.     

Glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) enzyme activities in different tissues of Sarotherodon mossambicus (Peters) exposed to a carbamate pesticide,carbaryl

The activity levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) enzymes were estimated in liver, muscle and brain tissues of the fish, Sarotherodon mossambicus (Peters), which had been exposed to sub-lethal (3 mg litre⁻¹) and lethal (25 mg litre⁻¹) concentrations of the carbamate insecticide carbaryl. Based on the results obtained, the changes in GOT and GPT levels in liver, muscle and brain following different periods of sub-lethal and lethal carbaryl exposures suggested that S mossambicus showed adaptive elevation in the activity levels of the two aminotransferase enzymes in the tissues, thereby probably aiding gluconeogenesis through transamination of glucogenic amino acids to meet the energy demand under carbaryl toxicity. © 1999 Society of Chemical Industry     

Amino acids in loose silky-bent (Apera spica-venti (L.) Beauv.) responding to prosulfocarb exposure and the correlation with physiological effects

Eleven free amino acids were identified in the grass weed loose silky-bent (Apera spica-venti) after exposure to four rates of the thiocarbamate herbicide prosulfocarb. A new HPTLC method was developed for quantification of amino acids in raw plant extracts. A pattern of significant changes in the content of glutamine, glycine, alanine, and proline due to exposure were detected. The content of all four amino acids increased at increasing exposure rates. Quantitative analyses 7 and 21 days after herbicide application showed that over time the amount of proline increased, the alanine and glycine content decreased, and that at high exposure rates the amount of glutamine increased. Visual effects were evaluated and the biomass was measured. The visual symptoms increased and the biomass decreased with increasing exposure rates. A significant correlation between the changes in the content of the four amino acids and the visual effects and the biomasses were found.     

Xenobiotic metabolism of plant secondary compounds in the English grain aphid, Sitobion avenae (F.) (Hemiptera: Aphididae)

Plant secondary compounds have been documented to be deleterious to insects and other herbivores in diverse ways. In this study, the effect of catechol (phenolics), gramine (alkaloid) and L-ornithine-HCI (non-protein amino acid) on the activities of xenobiotic metabolizing enzymes in English grain aphid, Sitobion avenae, was evaluated. Phase I enzymes investigated in this study included carboxylesterase (CarE), and oxidoreductase, whereas Phase II enzymes were represented by glutathione S-transferase (GST). In general, CarE and GST activities in S. avenae were positively correlated with the concentration of plant secondary compounds in artificial diets. Oxidoreductase activity, however, displayed a different profile. Specifically, peroxidase (POD) and polyphenol oxidase (PPO) activities in S. avenae were positively correlated with concentrations of dietary catechol and gramine, respectively, whereas catalase (CAT) activity was significantly suppressed by the higher concentration of catechol, gramine and L-ornithine-HCl. These combined results suggest that CarE and GST in S. avenae are key enzymes to breakdown a broad spectrum of plant secondary compounds, whereas oxidoreductase, including PPO and POD, degrades specific groups of plant secondary compounds.     

Effects of amino acids on the feeding behavior of the larva of the egyptian cotton leafworm,spodoptera littoralis boisd

The effect of 21 amino acids on the feeding response of larvae ofSpodoptera littoralis was investigated using the “Styropor method.” Lamellae of Styropor were treated(a) with different concentrations of amino acids,(b) different concentrations of amino acids mixed with 0.125 M sucrose, and(c) 0.125 M sucrose alone. The weight of Styropor consumed during 48 h served as the criterion of phagostimulation or phagodeterrency. With the sole exception of 0.125 M L-glutamic acid, no phagostimulation occurred in any of the amino acids tested in mixture with 0.125 M sucrose; none was phagostimulant when tested alone. Deterrency was found at 0.125 M in L-alanine, DL-alpha-amino-n-butyric acid, L-serine, L-cystine, L-methionine, L-tyrosine, and L-histidine, when mixed with an equimolar concentration of sucrose. Methionine was highly phagodeterrent also at 0.0625 M and, as was DL-alpha-amino-n-butyric acid, still active even at 0.0125 M. Chemical analysis showed that there was no decomposition of methionine applied on Styropor.     

Induced resistance againstPhytophthora capsici in pepper plants in response to DL-β-amino-n-butyric acid

Treatment of pepper plants with the nonprotein amino acid, DL-ß-amino-n-butyric acid (BABA) induced resistance to subsequent infection byPhytophthora capsici. In contrast, theα-, andγ-isomers of aminobutyric acid were ineffective as inducers of resistance. A relatively high concentration of BABA at 1,000μg ml^?1, which had no antifungal activityin vitro againstP. capsici, was required to induce resistance against Phytophthora blight with a foliar and stem spray, thus leading to complete control of the disease. About 1 day interval between BABA-treatment and challenge inoculation was sufficient to induce resistance in pepper plants. High inoculum levels ofP. capsici caused Phytophthora development slowly in pepper stems treated with BABA, especially at early plant growth stage, which suggests that the induced resistance in pepper plants may be more quantitative rather than qualitative. BABA applied to the root system also protected pepper stems fromP. capsici infection.     

Resistance to azoxystrobin in Alternaria isolates from pistachio in California

Failure to control Alternaria late blight in a few California pistachio orchards was observed after only 3-4 years of consecutive applications of azoxystrobin-based fungicide programs. A total of 72 isolates of Alternaria alternata, Alternaria tenuissima, and Alternaria arborescens, the causal organisms of Alternaria late blight, were collected from pistachio orchards with (58 isolates) and without (14 isolates) a prior history of azoxystrobin applications. The sensitivity to azoxystrobin was determined in conidial germination assays. Isolates from orchards with a history of azoxystrobin applications had EC₅₀ values greater than 100 μg/ml, whereas isolates from orchards without a prior history of azoxystrobin usage had EC₅₀ values ranging from 0.008 to 0.045 μg/ml. Azoxystrobin resistance correlated with a single mutation in the cytochrome b (cyt b) gene causing a change of glycine to alanine at amino acid position 143. A pair of PCR primers AF and AR was developed that amplified a 226-bp DNA fragment of the cyt b gene containing the mutation site from all three Alternaria species but not from 30 other fungal species frequently found on pistachio. PCR-restriction fragment length polymorphism (PCR-RFLP) analysis using the restriction enzyme Fnu4HI allowed differentiation of the PCR fragment of wild type cyt b gene from that of mutated gene. This method will aid in a fast detection of azoxystrobin resistance in these three Alternaria species.     

Translocation of mal secco toxin in lemons and its effect on electrolyte leakage,transpiration, and citrus callus growth

A bioassay test was developed for quantifying mal secco toxin based on electrolyte loss from treated carrot discs. A linear relationship was established between toxin concentration and electrolyte leakage as measured by conductivity of the bathing solution. The lowest amount of toxin which could be detected by this method was 32 μg/ml. The toxin decreased transpiration rate of tomato cuttings. A hyperbolic plot was obtained when reduction in transpiration rate was followed as a function of time. C¹⁴-labeled toxin was obtained by growing the fungus in the presence of radioactive amino acids. The purified radioactive toxin had a specific activity of 5.5 x 10⁴ cpm/mg toxin. Radioactivity was readily translocated in lemon cuttings. The detection of radioactivity in the leaves was correlated with symptoms’ appearance. Callus growth of a lemon cultivar highly susceptible to mal secco (Eureka) was inhibited by 0.3 mg toxin/ml, whereas an orange cultivar (Shamouti) was not affected by the toxin.     

Dynamic changes in pod and fungal physiology associated with the shift from biotrophy to necrotrophy during the infection of Theobroma cacao by Moniliophthora roreri

Theobroma cacao pods were inoculated with meiospores of Moniliophthora roreri (Mr), a hemibiotrophic basidiomycete causing frosty pod rot. Pods were malformed 30 days after inoculation (DAI) and sporulation was observed 60 DAI. Glucose and asparagine concentrations decreased and mannitol and malonate increased in infected pods 30 DAI. By 60 DAI, most carbohydrates, amino acids, and organic acids were drastically reduced by infection. Mannitol and succinic acid levels increased 60 DAI and likely originated from Mr. RT-qPCR analysis of cacao ESTs indicated a strong response to infection 30 DAI in malformed pod. Evidence indicated that biotrophic hyphae colonized pods and a shift to necrotrophic growth occurred later (during the end stages of infection). Expression of cacao ESTs associated with plant hormone biosynthesis and action was altered. Changes in the expression of Mr ESTs in response to nutrient deficiency in pure culture were small. Changes in Mr gene expression patterns and levels of specific metabolites in necrotic sporulating pods 60 DAI compared to malformed pods 30 DAI indicated that the glyoxylate cycle of Mr was up regulated during the shift from biotrophic to necrotrophic phases of the disease cycle.