Antifeedant activity of a novel 6-(4,7-hydroxy-heptyl) quinone? from the leaves of the milkweed Pergularia daemia on the cotton bollworm Helicoverpa armigera (Hub.) and the tobacco armyworm Spodoptera litura (Fab.)

The effects of crude extracts and an isolated compound from the leaves of milkweed, Pergularia daemia (Forssk) Choiv., on the antifeedant activity against two important lepidopteran pests, Helicoverpa armigera (Hub.) and Spodoptera litura (F.), were studied. Maximum antifeedant activity was recorded in ethyl acetate crude extract against H. armigera (70.3%) and S. litura (71.82%) at 1% concentration. Ethyl acetate crude extract was further subjected to column chromatography, which was performed using hexane as initial solvent and then by increasing the polar strength using ethyl acetate. Fractions collected at hexane and ethyl acetate (80:20) yielded 6-(4,7-hydroxy-heptyl) quinone, a novel compound which showed significant antifeedant activity against H. armigera (80.22% at 2000 ppm) and S. litura (68.31% at 2000 ppm).     

Genetic resources for arcelin,a stored product insect antimetabolic protein from various accessions of pulses of Leguminosae

Pulses, the most important source of high-quality dietary proteins are prone to serious damage due to insect pests, of which 20–25% damage was inflicted by stored product bruchid pest, Callosobruchus maculatus (F.). An alternative approach to control these insect pests apart from fumigation is the use of primary metabolites involved in plant defense mechanism. In the present study, one of such molecule, an insect anti-metabolic protein, arcelin was screened from nine different wild and cultivated varieties of pulses. Insect feeding bioassay with C. maculatus revealed that seven of these seed varieties were not infested by the bruchid insect pest. Additionally, the presence of arcelin polypeptide subunits (27–42 kDa) was demonstrated in the seeds of Phaseolus limensis L. and Phaseolus lunatus L. whereas, an insignificant amount was observed in Lablab purpureus L. Besides, seed kernel extract of P. lunatus registered a highest HA activity against native human-A erythrocytes and this activity was increased to several fold when the erythrocytes were treated with proteolytic enzymes revealing the characteristic feature of arcelin. Similarly, HA activity was observed when rat and mouse erythrocyte was treated with pronase, whereas, no titer value was observed upon treatment with its native erythrocytes. Of the 24 carbohydrates tested, only acetylated amino sugar, N-acetyl-d-galactosamine inhibited the agglutinating activity of crude seed extract against human-A RBC. Among the three glycoproteins tested, none were found potential to competitively inhibit the agglutination activity against human-A erythrocytes. Overall, this study reveals the presence of arcelin, an anti-metabolic insecticidal protein in seeds of P. lunatus.     

Sudden cardiac death in a dog during Holter recording—R on T phenomenon

A 6-year-old castrated male Golden Retriever was diagnosed with severe subaortic stenosis with severe left atrial enlargement and high heart rate due to atrial fibrillation. Treatment with digoxin and diltiazem to control ventricular response rate was initiated. Ambulatory electrocardiographic monitoring (Holter monitoring) was performed at the beginning of treatment and was repeated to evaluate the patient's response to drug therapy. Drug dose adjustments were made based on response to therapy as assessed by Holter monitoring. The dog experienced sudden death at home 19 days after beginning treatment while wearing the Holter monitor. Analysis of the Holter recording revealed marked increase in number and complexity of ventricular arrhythmias. A ventricular premature complex occurring on a T wave (R on T) was noted preceding the polymorphic ventricular tachycardia. This arrhythmia immediately degenerated into ventricular fibrillation followed by asystole. This case report describes the arrhythmia that preceded cardiac arrest and reviews the risk factors that could have potentiated the fatal arrhythmia in this dog.     

Protein Hydrolysates from Shrimp (Metapenaeus dobsoni) Head Waste: Optimization of Extraction Conditions by Response Surface Methodology

Utilization of shrimp head waste from the processing industry offers a solution to environmental pollution and also produces valuable bioactive peptides. The present study was aimed to optimize the alcalase assisted extraction conditions by response surface methodology (RSM) to obtain protein hydrolysates from shrimp (Metapenaeus dobsoni) head waste with maximum antioxidant activity. Based on the models derived by RSM, the optimized conditions for maximum degree of hydrolysis (DH) were pH 8.2, temperature of 45.4°C, and enzyme/substrate (E/S) of 1.8%. Meanwhile, the optimized conditions for maximum antioxidant activity of protein hydrolysates as measured by 2, 2-diphenyl-1-picrylhydrozyl (DPPH) and ferric reducing antioxidant power (FRAP) assays were pH 8.2 and 8.1, temperatures of 49.7 and 59.4°C, and E/S of 2.1 and 2.7%, respectively. The maximum predicted values for DH, DPPH, and FRAP were 42.44%, 39.64% inhibition, and 8.3 μM Fe (II)/g wet wt. of sample, respectively. The extraction of protein hydrolysates at optimal conditions derived by these models resulted in DH, DPPH, and FRAPs of 40.31%, 38.93%, and 8.21 μM Fe (II)/g of sample, respectively, demonstrating the fitness of the models. The present study demonstrates the potential of Metapenaeus dobsoni head waste as a source of protein hydrolysates with prospective antioxidant activity.     

Effect of combined inoculation of Azospirillum and Rhizobium on nodulation and N2-fixation of winged bean and soybean

Different strains of winged bean and soybean Rhizobium were tested with several strains of Azospirillum for combined inoculation in winged bean and soybean under temperate and tropical conditions.Substantial increases in nodulation, N₂-fixation, shoot dry matter production and N-gain due to the mixed inoculation were obtained in some combinations of these bacteria.The response to combined inoculation was mainly dependent upon the genotypes (strains) of these organisms. The influence of Rhizobium-genotype in expressing the associative effect was more decisive than that of Azospirillum. Cell-free extract of Azospirillum produced the same effect as that of the organism itself, while the culture supernatant also showed the same in some instances. The cell-free extract of Azospirillum strain KUL-X considerably reduced nodulation, N₂-fixation and N-gain of the Rhizobium strain RRIM-56, which was not otherwise affected by mixed inoculation. The combination of Azospirillum strain KUL-Y and Rhizobium strain KUL-BH produced the highest values of nodulation, N₂ - fixation and N-gain of all the Azospirillum—Rhizobium combinations in winged bean.     

In vitro studies on the selective cytotoxic effect of crocetin and quercetin

Crocetin (5-20 microg/ml), quercetin (10-40 microg/ml), and cisplatin (60-180 microg/ml) used as a positive control drug, were tested against human rhabdomyosarcoma (RD) cells and African green monkey kidney (Vero) cells. The cell viability, morphological changes, and lactate dehydrogenase activity were assessed. RD cell growth was found to be inhibited dose dependently by the three tested compounds. Morphological observation by phase contrast microscopy revealed that both crocetin and quercetin caused intense damage only on the malignant (RD) cells, whereas mild toxic effect was seen with cisplatin also on normal (Vero) cells.     

Neem oil as a potential seed dresser for managing Homopterous sucking pests of Okra (Abelmoschus esculentus (L.) Moench)

Insecticidal seed treatment is an alternative method to spray and granular applications. It can protect the crop right from germination to reproductive stage. Recurrent use of chemical insecticides destabilizes the ecosystem and enhances the development of resistance in pest population. Use of biopesticides like neem oil (NO) is a promising one in this situation. Two field experiments were conducted to test the efficacy of NO as a seed dresser (20 ml kg⁻¹) and the effect was compared with systemic chemical insecticides imidacloprid (7 g kg⁻¹) and carbosulfan (7 g kg⁻¹) and Pseudomonas fluorescens (10 g kg⁻¹). Field studies revealed that the neem oil 60EC (C) (NO 60EC (C)) recorded minimum population of sucking pests Leafhopper—Amrasca biguttula biguttula Ishida and Aphids—Aphis gossypii Glover (Homoptera: Cicadellidae and Aphididae), i.e., below the ETL (2 number per leaf) up to 45 days after sowing and provided better yield compared to control. Although the systemic chemical insecticide imidacloprid performed better by recording 11,280 and 11,580 kg ha⁻¹ of marketable fruit yield, NO 60EC (C) also recorded about twofold increase in marketable fruit yield 11,000 and 10,620 kg ha⁻¹, respectively, in 2001 and 2002 experiments. Results of this study suggest that NO could be used as a potential seed dresser for managing sucking pests in okra.     

Arcelins from an Indian wild pulse, Lablab purpureus, and insecticidal activity in storage pests

A partially purified protein fraction was isolated from seed flour of the Indian wild bean, Lablab purpureus, by ion exchange and size-exclusion chromatographies. Partially purified L. purpureus proteins had hemagglutination and glycoslyation properties similar to those of lectins or lectin-like proteins from other pulses. Data obtained from two-dimensional gel electrophoresis, MALDI-TOF, and MALDI-TOF/TOF and N-terminal protein sequencing of the isolated polypeptides from L. purpureus demonstrated that the extract contained proteins similar to isoforms of arcelins 3 and 4 and pathogenesis-related protein 1 (PvPR1) of Phaseolus vulgaris. L. purpureus proteins were resistant to degradation by the commercial enzymes trypsin and chymotrypsin and were moderately resistant to pepsin, but were readily hydrolyzed to smaller peptides by papain. Insect feeding bioassays of the extract with the storage pests Rhyzopertha dominica and Oryzaephilus surinamensis, internal and external feeders of grain, respectively, demonstrated that L. purpureus proteins at 2% in the diet resulted in retarded development. However, a 5% dose of the L. purpureus fraction resulted in complete mortality of all larvae in both species. This study has demonstrated that proteins in the partially purified L. purpureus extract have the potential to control storage pests in cereals transformed with L. purpureus defense-related genes, but the need for more studies regarding efficacy and safety is discussed.     

The response of phosphine-resistant lesser grain borer Rhyzopertha dominica and rice weevil Sitophilus oryzae in mixed-age cultures to varying concentrations of phosphine

The response of Rhyzopertha dominica and Sitophilus oryzae (both phosphine-resistant) in mixed-age cultures to phosphine at fixed concentration-time products (CT) of 10,500 to 168,000 microliters litre 1 h (ppm h) with either constant, rising or falling concentrations for 7 days was studied at 27 (+/- 2) degrees C. At lower CT products, rising concentrations of phosphine led to significantly fewer survivors of R dominica and S oryzae. Conversely, exposure to falling concentrations of phosphine resulted in significantly more survivors. The influence of changing concentrations of phosphine was more pronounced in S oryzae than in R dominica. In the latter, at the lower CT products of 21,000 and 42,000 microliters-1 h, the adult stage proved to be most tolerant, contrary to the accepted belief that the egg or pupal stage are always more tolerant to phosphine. The results indicate that application of phosphine in rising concentrations is more effective than in constant or falling concentrations.