Kropf D L, Coffman H R, Kloareg B, Glenn P, Allen V W
Department of Biology, University of Utah, Salt Lake City 84112.
Dev Biol. 1993 Dec;160(2):303-14. doi: 10.1006/dbio.1993.1309.
The developmental potentials of the rhizoid and thallus cells of two-celled Pelvetia embryos were investigated. Ablation of either the thallus or the rhizoid cell was accomplished by puncture with a micropipette. Thallus cells continued to divide repeatedly after rhizoid ablation, and in no case did the thallus initiate new rhizoid growth. In the reciprocal experiment, rhizoid cells elongated and divided in the normal transverse orientation after ablation of the thallus cell. The rhizoid did not appear to initiate a new thallus. Similar results were obtained when laser irradiation was applied to arrest division in one of the two cells. Thus, neither thallus nor rhizoid cell compensated for ablation or arrest of its sibling cell. The role of the cell wall-plasma membrane connections in organizing polar growth in the rhizoid cell was investigated by separating the wall from the protoplast. This was accomplished in two ways, by plasmolysis and by enzymatic wall digestion. Wall digestion yielded rhizoid cell protoplasts capable of wall regeneration and division, but the polar growth habit was irreversibly lost. Loss of polar growth correlated with loss of polarity in the microtubule cytoskeleton as visualized by indirect immunofluorescence using confocal microscopy. Transient plasmolysis of rhizoid cells resulted in abandonment of the preexisting apex and the initiation of a new rhizoid tip after rehydration. We suggest that interaction between the cell wall and the plasma membrane is involved in organizing polar growth.
对两细胞期鹿角菜胚胎的假根和叶状体细胞的发育潜能进行了研究。通过用微量移液器穿刺来去除叶状体或假根细胞。去除假根后，叶状体细胞继续反复分裂，且叶状体在任何情况下都不会启动新的假根生长。在反向实验中，去除叶状体细胞后，假根细胞以正常的横向方向伸长并分裂。假根似乎不会启动新的叶状体。当用激光照射使两个细胞中的一个停止分裂时，也得到了类似的结果。因此，叶状体细胞和假根细胞都不会补偿其姐妹细胞的去除或停止分裂。通过将细胞壁与原生质体分离，研究了细胞壁 - 质膜连接在假根细胞极性生长组织中的作用。这通过两种方式实现，即质壁分离和酶解细胞壁。酶解细胞壁产生了能够再生细胞壁并分裂的假根细胞原生质体，但极性生长习性不可逆转地丧失了。通过共聚焦显微镜间接免疫荧光观察，极性生长的丧失与微管细胞骨架极性的丧失相关。假根细胞的短暂质壁分离导致原有顶端的放弃，并在复水后启动新的假根尖端。我们认为细胞壁和质膜之间的相互作用参与了极性生长的组织过程。
