Ca2+ fluxes in developing Trichoderma viride mycelium.
The properties of both Ca2+ influx and efflux in the mycelium during the life cycle of Trichoderma viride were studied by means of 45Ca2+ and by X-ray fluorescence spectroscopy measurements. The properties of the 45Ca2+ influx and effluxes indicate that they are mediated by different transport systems. The Ca2+ influx could be mediated by an electrogenic Ca2+/nH+ antiport, or by an Ca2+ uniport system. Both Ca2+ influx and efflux were stimulated by the uncouplers (and the treatment leading to the suppression of energy metabolism) and by azalomycin F, an antifungal agent. Salicylate stimulated the Ca2+ efflux, but inhibited the Ca2+ influx. In the isolated preparation of crude vacuolar/mitochondrial fraction, salicylate induced the Ca2+ release, as did A23187. Azalomycin F moderately released Ca2+ from the microsomal fraction. On the other hand, uncouplers did not release Ca2+ from the isolated organelles, but inhibited to a different extent the ATP-dependent and -independent Ca2+ influx. The results could be explained in terms of the capacitative Ca2+ influx mechanism. The rate of 45Ca2+ influx, or of the 40Ca2+ content, was maximal after about 30 h of submerged cultivation, and then decreased. The results show that loading of internal Ca2+ stores occurs in the early stages of the development of mycelium only, and the Ca2+ influx mechanism is developmentally down-regulated, being almost nonexistent during its later stages. In older mycelium, growth seems to be autonomous of the extracellular Ca2+ until the onset of conidiation.
Simkovic
M
M
Department of Biochemistry and Microbiology, Slovak University of Technology, Bratislava, Slovak Republic.
Krystofová
S
S
Varecka
L
L
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D018942:Macrolides; D012459:Salicylates / Q000494:pharmacology; D013052:Spectrometry, X-Ray Emission; D013347:Subcellular Fractions / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014242:Trichoderma / Q000254:growth & development* / Q000378:metabolism; D014475:Uncoupling Agents / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D002132:Calcium Radioisotopes; D007476:Ionophores; D018942:Macrolides; D012459:Salicylates; D014475:Uncoupling Agents; C000232:azalomycin-F; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000001:Calcimycin; D002118:Calcium