Development and comparison of ELISA and PCR methods for the early detection of Ganoderma disease of coconut

Abstract

Molecular diagnosis, chemo-diagnosis and physiological parameter have been applied for detecting the Ganoderma disease of coconut. Polyclonal antibodies (PAbs) raised against mycelial protein of Ganoderma, specific mycelial protein (62 kDa) of Ganoderma isolates and basidiocarp protein of Ganoderma were used for detection. All the PAbs could detect Ganoderma in diseased coconut root tissues in early stage of the disease before symptom expression by indirect – ELISA at the antiserum dilution of 1:1000 for mycelial protein, 1:700 for specific protein and 1:3000 for basidiocarp protein. Low cross reactions were observed with saprophytic fungi occurring in coconut roots and also with other basidiomycetous fungi. For polymerase chain reaction tests, the primer was generated from the internal transcribed spacer region one (ITS 1) of rDNA of Ganoderma, which produced a PCR product of 167 bp in size. Utility of this method was confirmed at the field level.     

Biological control of onion leaf blight disease by bulb and foliar application of powder formulation of antagonist mixture

Abstract

Three antagonists: Pseudomonas fluorescens (Pf1), Bacillus subtilis and Trichoderma viride, were tested alone and in combination for suppression of onion leaf blight (Alternaria palandui) disease under glasshouse and field conditions. The average mean of disease reduction was 24.81% for single strains and 42.44% for mixtures. In addition to disease suppression, treatment with a mixture of antagonists promoted plant growth in terms of increased plant height and ultimately bulb yield. Though seed treatment of either single strain or strain mixtures alone could reduce the disease, subsequent application to root, leaves or soil further reduced the disease and enhanced the plant growth. The mixture consisting of Pseudomonas fluorescens Pf1 plus Bacillus subtilis plus Trichoderma viride was the most effective in reducing the disease and in promoting plant growth and bulb yield in greenhouse and field tests.     

Sexual Dimorphism in Juvenile Hormone Synthesis by Corpora Allata and in Juvenile Hormone Acid Methyltransferase Activity in Corpora Allata and Accessory Sex Glands of Some Lepidoptera

Summary

The kinetic profiles of vitellin accumulation in the oyster ovary during oocyte growth and the effects in vivo and in vitro of estradiol-17β (E₂) on vitellin formation were examined in this study. The relative vitellin content measured by an enzyme-linked immunosorbent assay (ELISA) shows an apparent increase as the oocyte develops. Immunoblotting of the vitellin using anti-vitellin indicated that two main bands (179 and 110 kD), which begin to accumulate at an early stage of maturation, become pronounced during oocyte growth. Meanwhile, the major peak of the intact form of vitellin (530 kD) in gel filtration also enlarges with oocyte growth, supporting the results of immunoblot analysis and vitellin determination. E₂ treatment in vivo causes significant increases in oocyte diameter and vitellin content in the female oyster. A similar trend was observed in ovarian tissues cultured in the presence of E₂. It is concluded that E₂ is one of the major factors which control the vitellogenesis in the oyster and that the ovary is undoubtedly the site of synthesis of vitellin.     

Food selection and utilization in a danid butterfly

Summary Larvae of the danid butterfly Danaus chrysippus, fed on the milkweeds Calotropis gigantea and Asclepias curassavica grew successfully during the 9-day feeding period and pupated. In the presence of these milkweeds, the larvae preferred to feed on C. gigantea. Their preference was more pronounced during the final 2 instars than during the initial 3 instars. They consumed 605 mg, defecated 308 mg, and converted 115 mg of C. gigantea; those receiving A. curassavica consumed 563 mg, defecated 287 mg and converted 85 mg. They assimilated either food with equal efficiency (: 46%; : 50%). But they differed significantly in their efficiency in converting the assimilated food. The presence of a greater amount of latex in C. gigantea than in A. curassavica and/or the nutritional inadequacy of the latter food may perhaps be the reason(s) for the preference of C. gigantea by D. chrysippus larvae over A. curassavica.     

A Structural Biology Approach to Understand Human Lymphatic Filarial Infection

The presence of aspartic protease inhibitor in filarial parasite Brugia malayi (Bm-Aspin) makes it interesting to study because of the fact that the filarial parasite never encounters the host digestive system. Here, the aspartic protease inhibition kinetics of Bm-Aspin and its NMR structural characteristics have been investigated. The overall aim of this study is to explain the inhibition and binding properties of Bm-Aspin from its structural point of view. UV-spectroscopy and multi-dimensional NMR are the experiments that have been performed to understand the kinetic and structural properties of Bm-Aspin respectively. The human aspartic proteases that are considered for this study are pepsin, renin, cathepsin-E and cathepsin-D. The results of this analysis performed with the specific substrate [Phe-Ala-Ala-Phe (4-NO₂)-Phe-Val-Leu (4-pyridylmethyl) ester] against aspartic proteases suggest that Bm-Aspin inhibits the activities of all four human aspartic proteases. The kinetics studies indicate that Bm-Aspin follows a competitive mode of inhibition for pepsin and cathepsin-E, non-competitive for renin and mixed mode for cathepsin-D. The triple resonance NMR experiments on Bm-Aspin suggested the feasibility of carrying out NMR studies to obtain its solution structure. The NMR titration studies on the interactions of Bm-Aspin with the proteases indicate that it undergoes fast-exchange phenomena among themselves. In addition to this, the chemical shift perturbations for some of the residues of Bm-Aspin observed from ¹⁵N-HSQC spectra upon the addition of saturated amounts of aspartic proteases suggest the binding between Bm-Aspin and human aspartic proteases. They also provide information on the variations in the intensities and mode of binding between the proteases duly corroborating with the results from the protease inhibition assay method.