Cell biology analyses on the synthesis and localization of the proteins in fungal cells

1.白念珠菌胞内分泌型天冬氨酸蛋白酶检测的生化研究白念珠菌在含有牛血清白蛋白作为唯一氮源的培养基中分泌酸性蛋白酶(EPR)。用EPR抗血清免疫印迹检测，从不同的膜组分回收的胞质组分中分别检测到43和45 kDa的蛋白。45 kDa可能是分泌43 kDa蛋白的前体。2.碱性铋染色法和免疫细胞化学法对胰蛋白酶分泌细胞的超微结构研究我们发现在蛋白酶分泌细胞的细胞外围有许多絮状颗粒，但这些颗粒并不是分泌所特有的。这是从碱性铋染色、分泌抑制剂Brefeldin A的效果以及使用抗EPR血清的免疫电子显微镜观察得出的。3.白念珠菌胞外蛋白酶(EPR)诱导的生化研究结果表明，只要以葡萄糖为碳源，不加氮源即可诱导EPR，无论有无氮源，pH>6.0时EPR均不能诱导。提示EPR的产生和胚管的形成在侵袭过程中起着不同的作用。4.用荧光显微镜和电子显微镜研究F-肌动蛋白在裂殖酵母中的行为。(I)在蒸馏水中饥饿使细胞末端的肌动蛋白点分散成遍布细胞质的厚片和索状物。(Ii)细胞松弛素A在隔膜形成前抑制细胞赤道处肌动蛋白环的出现，并使细胞质中的小泡和二体变为致密小体。肌动蛋白网络维持着包括腺体和囊泡在内的分泌途径的组织。

1. Biochemical studies on the detection of intracellular forms of secreted aspartic proteinase in Candida albicans. C. albicans secretes acid proteinase (EPR) in the medium which contains bovine serum albumin as a sole source of nitrogen. By immunoblotting with anti-EPR serum, 43 and 45 kDa proteins were detected in the cytoplasmic fraction, which recovered from the different membrane fractions. 45 kDa would be a precursor of the secreting 43 kDa protein. 2. Ultrastructure studies on the proteinase secreting cells by alkaline bismuth staining and immunocytochemistry. We found many flocculent granules at the cell periphery of the proteinase-secreting cells, but the granules were not specific for the secretion. This was deduced from observations of alkaline bismuth staining, of effects of a secretion inhibitor Brefeldin A, and of immunoelectron microscopy using anti-EPR serum. 3. Biochemical studies on the induction of extracellular proteinase (EPR) in Candida albicans. It was shown that EPR was induced without the addition of nitrogen source so long as glucose as a carbon source is present, and not induced at a pH greater than 6.0 irrespective of the presence of nitrogen source. the results suggested EPR production and germ tube formation play different roles in the invasive process. 4. Studies on the behavior of F-actin in Schizosaccharomyces pombe by fluorescent and electron microscopy. (i) Starvation in distilled water dispersed the actin dots localized at the cell ends into thick patches and cables throughout the cytoplasm. (ii) Cytochalasin A inhibited the appearance of actin ring at a cell equator before septum formation and cytoplasmic vesicles and dictyosomes were altered in to dense bodies in the cytoplasm. Actin network maintains the organization of the secretory pathway involving dictyosomes and vesicles.