酿酒酵母细胞增殖对Ca~(2+)需求的新证据

本文研究了酿酒酵母细胞增殖对Ca2+需求的证据。结果表明:SD-Ca培养基中外加1mmol/L的Ca2+明显促进酿酒酵母细胞增殖,外源Ca2+浓度在0~20mmol/L范围内变动时,随Ca2+浓度增加,细胞生长到达稳定期的终浓度也越大;5、10mmol/L的EGTA可明显延缓细胞生长的延滞期,但是最终不能抑制细胞增殖;酿酒酵母在SD-Ca培养基中继代培养4次,随增殖代数增加,细胞总钙含量没有明显变化,说明酵母能够在低钙介质中生长可能是因为具有捕捉和富集钙的功能;以Fluo-3作为胞质Ca2+指示剂,通过激光扫描共聚焦显微镜观察,发现随胞外Ca2+浓度增加,胞质中游离Ca2+浓度也相应增加。这些证据都揭示了Ca2+在酿酒酵母细胞增殖过程中是必需的。

NEW EVIDENCE OF CALCIUM REQUIREMENT FOR CELL PROLIFERATION OF SACCHAROMYCES CEREVISIAE

Cell proliferation of Saccharomyces cerevisiae was evidently stimulated by adding 1mmol/L Ca2+ to SD-Ca medium. 0~20 mmol/L exogenous Ca2+ stimulated the cell proliferation of S.cerevisiae mainly by accelerating the growth rate and increasing the cell density on the stationary phase. 5 and 10 mmol/L EGTA prolonged the lag phase of the cell growth. However, with the increase of cell density, the inhibiting effect by EGTA disappeared. When S.cerevisiae reinoculated to SD-Ca medium for 4 times, the total calcium content of cell kept stable, which showed that yeast might have high ability to enrich Ca2+ from low-Ca2+ medium. Fluo-3 as the Ca2+ fluorescent indicator was applied to detect the cytosolic free calcium concentration under laser scanning confocal microscopy(LSCM). With the increase of exogenous Ca2+ concentration, the cytosolic free Ca2+ concentration increased. All the results proved Ca2+ was required in the proliferation of S.cerevisiae.