The Functional Significance of Sporopollenin in the Morphogenesis of the Cellular Slime Moulds

在细胞黏菌达到顶峰的形态发生过程中，茎鞘和细胞壁的生物合成和沉积对于了解形态发生的机制以及细胞形状和刚性的建立具有特别重要的意义。一种耐碱和耐酸的聚合物(孢粉蛋白)位于子实体的柄鞘上，形成一束细纤维(约4纳米厚)。多种化学分析表明，构成茎鞘的聚合物(简称SSM)和完整的茎细胞壁都是葡萄糖的均聚体。如前所述，茎细胞壁似乎是由纤维素组成的。然而，SSM不太可能是纤维素，因为它对广泛的纤维素酶处理相当抵抗，而且对PAS(高碘酸希夫)反应也是阴性的。综合这些结果，推测SSM是一个紧密的葡萄糖均聚体网络，具有大量的分支，因此对各种化学处理具有高度的抗性。讨论了SSM的生物学意义，特别是对黏菌细胞发育后期的影响。

During the morphogenetic events of culmination of the cellular slime moulds, the biosynthesis and deposition of stalk sheath and cell wall are of particular for an understanding of the mechanism of morphogenesis as well as the establishment of cell shape and rigidity. An alkali- and acid-resistant polymer (sporopollenin) is located on the stalk sheath of fruiting bodies as a bundle of fine fibrils (ca. 4 nm thick). Both the stalk sheath-constituting polymer (referred as to SSM) and the intact stalk cell wall were shown by several kinds of chemical analysis to be a homo-polymer of glucose. The stalk cell wall seemed to be composed of cellulose, as described previously. However, it is unlikely that the SSM is cellulose, because it is quite resistant to extensive cellulase-treatment and also is negative to PAS (periodic acid Schiff) reaction. Taken together these results, it is supposed that the SSM is a tight network of homo-polymer of glucose with a great many of branchings, thus being highly resistant to various chemical treatments. The biological significance of SSM is discussed, with special reference to the late developmental stages of slime mould cells.