Biomedical subjects

M Gresík

Publications and source records attributed to M Gresík.

3 recordsLinked to original sources

PubMed1992

Light-activated adenyl cyclase from Trichoderma viride.

The effect of light on adenyl cyclase (E.C. 4.6.1.1) and 3':5'-cyclic-AMP-phosphodiesterase (E.C. 3.1.4.17) activity of Trichoderma viride was investigated. Adenyl cyclase proved to be a membrane-associated enzyme, requiring Mn2+ and was activated by light. In contrast, 3':5'-cyclic-AMP-phosphodiesterase showed no light-stimulated activity. The activity of 3':5'-cyclic-AMP-phosphodiesterase was present mainly in the cytosol and was stimulated by Mg2+.

1-Methyl-3-isobutylxanthine↗

PubMed1991

Hyperpolarization and intracellular acidification in Trichoderma viride as a response to illumination.

Using indirect methods based on uptake of [3H]tetraphenylphosphonium cation and [14C]benzoic acid by cells of the fungus Trichoderma viride we found that the illumination-induced transient hyperpolarization of the plasma membrane is followed immediately by a rapid temporary decrease in intracellular pH. Hyperpolarization and intracellular acidification were completely suppressed by 150 mM-KCl and by the K(+)-ionophore valinomycin. The light-induced acidification of the cytoplasm was not observed in the presence of the cytochrome respiratory chain inhibitors antimycin A and mucidin. Based on these results, we hypothesize that the hyperpolarization of the cells is the consequence of an efflux of K+ through a light-activated K(+)-channel in the plasma membrane. The loss of positive charge in the cytoplasm caused by this efflux of cations is counterbalanced by H+ originating from the light-activated mitochondrial respiratory chain.

Hydrogen-Ion Concentration↗

PubMed1989

Light-stimulated phosphorylation of proteins in cell-free extracts from Trichoderma viride.

When illuminated by visible light, cell-free extracts from the fungus Trichoderma viride catalysed the phosphorylation of at least two proteins with molecular masses of 18 and 114 kDa which were practically absent when the phosphorylation was performed in the dark. The effect of light could be substituted by 3mM cyclic AMP, not only in the cell-free extract, but also in the separated cytosol. It is concluded that the process of photoinduced conidiation in Trichoderma involves phosphorylation of conidiation-specific proteins by (a) cyclic AMP-dependent protein kinase(s) present in the cytosol.

Autoradiography↗