Relationship between preformed/post-infectional antifungal substances in leaves of Panicum repens L. and compatibility with Pyricularia spp

Preformed and post-infectional antifungal substances appear to be involved in the compatibility of pyricularia spp. with panicum repens L. Diffusates and extracts of 'uninoculated' or leaves inoculated with the compatible or incompatible isolates showed antifungal activity. However, the antifungal activity was found to be localized. Antifungal activity was also evident in mechanically injured leaves or leaves treated to cell free germination fluid of an incompatible isolate. The presence of preformed and post-infectional protectants was confirmed by thin-layer chromatography. Post-infectional protectants appeared earlier in leaves inoculated with the incompatible isolate than in leaves inoculated with the compatible isolate. The incompatible isolate was more sensitive than the compatible isolate to preformed and post-infectional protectan's

Studies on the toxins of Pyricularia spp.-the phytotoxicity of culture filtrates

Filtrates from cultures of 5Pyricularia spp. from different graminaceous hosts and, isolates of P. oryzae from rice belonging to 10 races were analysed for phytotoxic components by thin-layer chromatography and bioassay techniques. A number of phytotoxic components including pyriculol was detected. A component which was apparently the reduced form of pyriculol was also detected in some of the toxic eluates of the chromatograms. The components could be distinguished by their characteristic UV absorption spectra. Most of the components appeared to be unsaturated and phenolic in nature. The number and nature of the components varied with the isolate, medium and cultural condition

Treatment compliance in relation to source of referral and initial reaction to the diagnosis of tuberculosis

The source of referral and patient’s reaction to diagnosis were studied in relation to regularity of treatment in 107 patients attending Tuberculosis Research Centre (TRC), Chennai. In all, 29% of the patients were referred by family members, 27% by neighbours and friends, 11% attended on their own, private practitioners referred 18% and government facilities/NGOs referred 15%. The initial reactions to diagnosis of tuberculosis were anxiety, fear, worry and/or shock in 59%. Only 31% of the patients were hopeful of cure at the time. All those who attended on their own completed > 80% of treatment as did 90% of those who were hopeful of cure at the time of diagnosis. And, 86% of those who experienced a negative reaction (fear of death, anxiety and worry) completed > 80% of treatment

Reentrant spin glass behavior in a layered manganite La1.2Sr1.8Mn2O7 single crystals

We report here a detailed study of AC/DC magnetization and longitudinal/transverse transport properties of La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystals below $T_{c}$ = 121 K. We find that the resistivity upturn below 40 K is related to the reentrant spin glass phase at the same temperature, accompanied by additional anomalous Hall effects. The carrier concentration from the ordinary Hall effects remains constant during the transition and is close to the nominal doping level (0.4 holes/Mn). The spin glass behavior comes from the competition between ferromagnetic double exchange and antiferromagnetic superexchange interactions, which leads to phase separation, i.e. a mixture of ferromagnetic and antiferromagnetic clusters, representing the canted antiferromagnetic state.Comment: 5 pages, 5 figures, submitted to Phys. Rev.

Sporulation of Pyricularia spp. in culture. effect of some aromatic compounds

The effect of L-tyrosine, DL-phenylalanine, shikimic acid and chlorogenic acid on sporulation was studied with six isolates of Pyricularia from different gramineous hosts. In general, the isolates from cultivated gramineae sporulated better than the isolates from the wild grasses. The effect of the compounds on sporulation varied with the isolate. Possible genetic differences among the isolates are invoked to explain the results

Resistive relaxation in field-induced insulator-metal transition of a (La0.4_{0.4}Pr0.6_{0.6})1.2_{1.2}Sr1.8_{1.8}Mn2_{2}O7_{7} bilayer manganite single crystal

We have investigated the resistive relaxation of a (La$_{0.4}$Pr$_{0.6}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystal, in order to examine the slow dynamics of the field-induced insulator to metal transition of bilayered manganites. The temporal profiles observed in remanent resistance follow a stretched exponential function accompanied by a slow relaxation similar to that obtained in magnetization and magnetostriction data. We demonstrate that the remanent relaxation in magnetotransport has a close relationship with magnetic relaxation that can be understood in the framework of an effective medium approximation by assuming that the first order parameter is proportional to the second order one.Comment: 6 pages,5 figure

Role of nitrogen in host susceptibility to piricularia oryzae cav

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Stretched exponential behavior in remanent lattice striction of a (La,Pr)1.2_{1.2}Sr1.8_{1.8}Mn2_{2}O7_{7} bilayer manganite single crystal

We have investigated the time dependence of remanent magnetostriction in a (La,Pr)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$ single crystal, in order to examine the slow dynamics of lattice distortion in bilayered manganites. A competition between double exchange and Jahn-Teller type orbital-lattice interactions results in the observed lattice profile following a stretched exponential function. This finding suggests that spatial growth of the local lattice distortions coupled with e$_{g}$-electron orbital strongly correlates with the appearance of the field-induced CMR effect.Comment: 3 figure

Tracer techniques in plant pathology

Isotope techniques have been valuable in understanding many fundamental aspects of plant disease, particularly these caused by obligate parasites like rusts and mildews. Autoradiography, microautoradiography and other tracer techniques have thrown considerable light on the mobilization of materials to the infection court, shifts in metabolic pathways, RNA and protein synthesis in the host-parasite complex as well as on the metabolic machinery of uredospores. The present article summarizes current knowledge on obligate parasitism gained through tracer techniques