Effect of a chemical analogue of autoinducers of microbial anabiosis on the Ca super(2+) response of mycelial fungi

• Published in: Microbiology (New York) 2004-11, Vol.73 (6), p.635-642
• Main Authors: Kozlova, O V, Kupriyanova-Ashina, F G, Egorov, SYu, El-Registan, GI
• Format: Article
• Language: English
• Subjects: Aspergillus awamori; Micromycetes
• ISSN: 0026-2617; 1608-3237
• DOI: 10.1007/s11021-005-0003-1

The microbial alkylhydroxybenzenes (AHB), which are anabiosis autoinducers also termed d sub(1) factors, participate in the stress response of mycelial fungi, as determined from changes in intracellular Ca super(2+) concentration. By using the genetically modified strain Aspergillus awamori 66A, which produces the recombinant Ca super(2+)-dependent protein aequorin, the dynamics of Ca super(2+) was studied in the cytosol of cells exposed to mechanical shock in the presence of protective doses (0.001-0.01% w/vol) of a chemical AHB analogue, 4-n-hexylresorcinol. As under stressful conditions, Ca super(2+) concentration increases in the cell cytosol in response to an enhanced AHB level in a growing fungal culture; thus, AHB is perceived by cells as a stress signal. The level of cell response, which was determined from the amplitude of luminescence dependent on the Ca super(2+) concentration in the cytosol, was related to the physiological age of the cells and the AHB concentration. Micromycete preincubation with AHB was found to protect cells from subsequent stress; this was reflected in the Ca super(2+) response. The protective AHB effect was manifested as (1) a significant decrease in the amplitude of luminescence and, thus, in Ca super(2+) accumulation in the cytosol during subsequent mechanical stress (as compared to the control-mechanical stress only); (2) development of a secondary Ca super(2+) response, which was not observed in the control; and (3) a high level of Ca super(2+) retained in the cytosol for a long time in the presence of AHB (as compared to the control without preincubation with AHB). The mechanisms underlying the AHB effect on Ca super(2+) transport systems are discussed.