Cytological studies on the mechanism of hydrocarbon synthesis by a green alga, Botryococcus braunii

丛生绿藻--布氏芽孢杆菌会产生异常高水平的碳氢化合物，相当于其干重的30%-60%，并聚集在细胞表面。通常，碳氢化合物的合成发生在细胞分裂之后，但在多糖细胞壁形成之前。在本研究中，我们将相间细胞的诱导系统发展为活性碳氢化合物合成。活性碳氢化合物的合成是在间期细胞(球形体)的细胞壁被消化后发生的，而不是通过去除已经积累的碳氢化合物而发生的。球形体诱导的碳氢化合物合成量是正常间期细胞的12倍。球体中高尔基体和跨高尔基网络(TGN)的形态与正常间期细胞不同，而是细胞分裂后的形态。这一结果有力地支持了TGN参与烃类合成的假说。然后，我们克隆了β-COP的编码基因，它是一种介导囊泡通过高尔基体和TGN的囊泡运输的外壳蛋白。该基因编码一个由947个氨基酸组成的蛋白质，预测分子质量为109 kDa。用抗β-COP抗体进行免疫电子显微镜分析。为了生产布氏芽孢杆菌的球形体，我们对其细胞壁的多糖和糖组成进行了检测，明确了布氏巴氏杆菌具有特征性的特征。

The colonial green alga Botryococcus braunii produces unusually high levels of hydrocarbons, amounting to 30%-60% of its dry weight, and accumulates them around the cell surfaces. Usually, the hydrocarbon synthesis occurrs just after cell division but before the formation of polysaccharide cell wall. In this study, we developed the induction-system of interphase cells into an active hydrocarbon synthesis. Active hydrocarbon synthesis occurred after the digestion of cell walls in interphase cells (spheroplasts), but didn't occur by the removal of already accumulated hydrocarbons. Maximally, we could induce 12 times of hydrocarbon synthesis by spheroplasts than those by normal interphase cells. The morphologies of Golgi bodies and the trans-Golgi networks (TGN) in spheroplasts were not similar to those in normal interphase cells, but those in cells just after cell division. The result strongly supports our hypothesis that the TGN is participated in the hydrocarbon synthesis. Then, we have isolated a cDNA coding for β-COP that is a coat-protein of transport vesicles mediating the vesicular transport through the Golgi apparatus and the TGN. The cDNA encodes a protein of 947 amino acids with a predicted molecular mass of 109 kDa. Immunoelectron microscopic analysis was also carried out with the anti-body against β-COP. To produce spheroplasts of B. braunii, we examined the polysaccharide and sugar compositions of the cell wall, and it was clarified that B.braunii had a characteristic one.