Avirulent mutants of Macrophomina phaseolina and Aspergillus fumigatus initiate infection in Phaseolus mungo in the presence of phaseolinone; levamisole gives protection.

To evaluate the role of phaseolinone, a phytotoxin produced by Macrophomina phaseolina, in disease initiation, three nontoxigenic avirulent mutants of the fungus were generated by UV-mutagenesis. Two of them were able to initiate infection in germinating Phaseolus mungo seeds only in the presence of phaseolinone. The minimum dose of phaseoli-none required for infection in 30% seedlings was 2 5 mg/ml. A human pathogen, Aspergillus fumigatus was also able to infect germinating seeds of P. mungo in the presence of 5 mg/ml concentration of phaseolinone. Phaseolinone seemed to facilitate infection by A. fumigatus, which is not normally phytopathogenic, by reducing the immunity of germinating seedlings in a nonspecific way. Levamisole, a non-specific immunopotentiator gave protection against infection induced by A. fumigatus at an optimum dose of 50 mg/ml. Sodium malonate prevented the effects of levamisole.

Kinetoplast DNA minicircle binding proteins in a Leishmania Spp: interference of protein DNA interaction by berenil.

A kinetoplast DNA minicircle of a Leishmania Spp. binds to several proteins of the kinetoplast Lysates of kinetoplasts of Leishmania grown in the presence of berenil show complete disappearance of some of these protein bands, while the rest of the proteins present appear as much less intense bands in South Western blots when probed with either the conserved or variable regions of the minicircle or whole minicircle DNA. The conserved region of minicircle DNA complexed with berenil in vitro also fails to interact with the DNA binding proteins of kinetoplast of untreated cell in South Western blots. Since berenil induces dyskinetoplasty of kinetoplastidae, the results indicate that interference of protein-DNA interaction in the presence of berenil may be the primary event in making organisms dyskinetoplastic.