Martinez J P, Gil M L, Casanova M, Lopez-Ribot J L, Garcia De Lomas J, Sentandreu R
Departamento de Microbiología, Facultad de Farmacia, Universitat de València, Spain.
J Gen Microbiol. 1990 Dec;136(12):2421-32. doi: 10.1099/00221287-136-12-2421.
Candida albicans ATCC 26555 switched at high frequency (10(-1) to 10(-3)) between several phenotypes identified by colony morphology on a defined mineral amino-acid-containing agar medium supplemented with arginine and zinc (LAZ medium). When cells taken from colonies exhibiting distinct morphologies were plated directly onto LAZ agar, spontaneous conversion to all the variant phenotypes occurred at combined frequencies of 2.1 x 10(-1) to 9.5 x 10(-3). However, when cells taken from the different colonial phenotypes were plated directly onto an undefined medium (yeast extract/peptone/dextrose; YPD medium), or first incubated in liquid YPD medium and then cloned on YPD agar, all colonies observed exhibited the same phenotype (smooth-white). When cells from the smooth-white colonies were plated as clones on LAZ agar, the original switch phenotype reappeared. These results suggest that environmental conditions such as the growth medium (and possibly the temperature) influence switching by suppressing phenotype expression, but have no effect on genotype. The variant colony morphologies also appeared to be associated with differences in the relative proportions of yeast and mycelial cells. Zymolyase digests of wall preparations obtained from cells belonging to different colonial phenotypes were analysed by SDS-PAGE. After blotting to nitrocellulose paper, the mannoproteins were stained with Concanavalin A, with a polyclonal antiserum enriched in antibodies against mycelium-specific wall components, and with a monoclonal antibody raised against a high-molecular-mass mannoprotein band (260 kDa) specific to the walls of mycelial cells. The results suggest that phenotypic switching might be associated with changes in the degree of glycosylation in high-molecular-mass mannoproteins, or in the way these mannoproteins are bound to other cell wall components.
白色念珠菌ATCC 26555在添加了精氨酸和锌的特定含矿物质氨基酸的琼脂培养基（LAZ培养基）上，能以较高频率（10⁻¹至10⁻³）在几种通过菌落形态鉴定的表型之间转换。当从呈现不同形态的菌落中取出细胞直接接种到LAZ琼脂上时，自发转换为所有变异表型的总频率为2.1×10⁻¹至9.5×10⁻³。然而，当从不同菌落表型中取出的细胞直接接种到成分不明确的培养基（酵母提取物/蛋白胨/葡萄糖；YPD培养基）上，或者先在液体YPD培养基中培养然后在YPD琼脂上克隆时，观察到的所有菌落都呈现相同的表型（光滑白色）。当将光滑白色菌落中的细胞作为克隆接种到LAZ琼脂上时，原来的转换表型又重新出现。这些结果表明，诸如生长培养基（可能还有温度）等环境条件通过抑制表型表达来影响转换，但对基因型没有影响。变异的菌落形态似乎也与酵母细胞和菌丝体细胞的相对比例差异有关。通过SDS-PAGE分析了从属于不同菌落表型的细胞制备的细胞壁的溶菌酶消化产物。将其印迹到硝酸纤维素纸上后，用伴刀豆球蛋白A、富含针对菌丝体特异性细胞壁成分的抗体的多克隆抗血清以及针对菌丝体细胞壁特有的高分子量甘露糖蛋白条带（260 kDa）产生的单克隆抗体对甘露糖蛋白进行染色。结果表明，表型转换可能与高分子量甘露糖蛋白的糖基化程度变化或这些甘露糖蛋白与其他细胞壁成分的结合方式变化有关。
