内质网在细菌周膜形成中的作用

ROLE OF ENDOPLASMIC RETICULUM IN THE FORMATION OF PERIBACTEROID MEMBRANES

在大豆根瘤侵染细胞中,细胞器的变化以内质网最引人注目,不仅数量大大增多,而且常常膨大形成较宽的腔隙。内质网的膨大以端部尤为明显,并在此形成各种各样的小泡,有时也形成一种葫芦形结构。小泡和葫芦形结构一般都含有纤维状物质,然后它们脱离内质网而掉入寄主细胞质中。掉入寄主细胞质中的小泡不断向细菌移动,逐渐靠近细菌周膜,进而与细菌周膜融合,在细菌周膜上形成一种乳头状突起,突起中常有纤维状物质。随着细菌周膜的发育,这些突起及其里面的纤维状物质也日趋消失,其被膜便发育为细菌周膜的一部分。

The relation between the endoplasmic reticulum and peribacteroid membranes during the development of infected cells of Chinese soybean (Glycine max L. cv. Harvest 11) root nodules by transmission electron microscopy was observed. After the host cells are infected by bacteria, the ultrastructures of the infected cells appear to have many changes, such as that their cytoplasm becomes thicker, the vacuoles decrease in size and organelles rapidly increase in number, among these organeIle changes are more obvious than the others. However, changes of endoplasmic reticulum is mostly striking. It is not only increases greatly in number but often swells and forms wider inter-spaces. The swelling of endoplasmie reticulum is especially conspicuous at its ends and often form various vesicles. Sometimes, the front part of the endoplasmic reticulum also forms a gourd-shaped structure, which together with the vesicles usually contain fibrillar material. After they are released from the endoplasmic reticulum to the host cytoplasm, they continuously move towards neighbouring bacteria and close to the peribacreroid membranes. The gourd-shaped structures always locate near but never fuse with the peri- bacteroid membranes. However, the vesicles can do that and form a kind of papillae, often containing fibrillar material, on the peribacter oid membranes. These papillae and their fibrillar material gradually disappear whilst the membrane of the vesicle derived from endoplasmic reticulum becomes one part of the peribacteroid membrane by way of fusing with the latter to form a papilla on it.