Thallus reconstruction of nongeniculate coralline algae (Corallinales, Rhodophyta)

研究了非膝状体珊瑚藻体的重建。在琉球群岛石垣岛Kabira湾的石珊瑚（Lithophyllum pallescens）的分支顶端，人工地在其上形成水平和垂直的疤痕，形成巨石般大小的结节。对瘢痕恢复过程的时间序列观察揭示了以下内容。(1)当形成水平瘢痕时，多数情况下，位于断裂细胞下面几层细胞的细胞成为分生组织细胞，向外产生新的上皮细胞，向内产生营养细胞。新生上皮细胞上方的死细胞脱落。很少有新的组织产生于疤痕周围的未受损部分;疤痕通过随后的新组织侧向生长而恢复。(2)在垂直疤痕重建的情况下，新细胞在疤痕的边缘、侧面和底部形成。结果表明，珊瑚藻体具有良好的修复食草动物损伤的能力，上皮细胞在珊瑚藻体死亡部分的脱落中起着积极的作用，尽管它们被认为是终止丝状体或具有通过脱落去除有害物体如其它藻类孢子的功能的细胞。

Reconstruction of nongeniculate coralline algal thalli was investigated. Horizontal and vertical scars were artificially given on the branch tips of Lithophyllum pallescens growing as up to boulder-sized nodules in Kabira Cove, Ishigaki-jima, Ryukyu Islands. Time-series observations on the course of the recovery of scars have revealed followings.(1) When the horizontal scars were given, in most cases, those cells located several-cell-layrs beneath the broken cells became meristem cells that produced new epithallial cells outwardly and vegetative cells inwardly. Then the dead cells above the new epithallial cells were sloughed off. Rarely new tissues were generated from undamaged parts encircling the scars ; the scars were recovered by subsequent lateral growths of the new tissues.(2) In the case of the reconstruction of vertical scars, new cells were formed at the edges, sides, and bottoms of scars. Newly-formed tissues are dimerous at the edges and sides, while those at the bottoms are monomerous or dimerous.These results demonstrate that coralline algal thalli possess excellent capability of recovering scars by herbivores and that epithallial cells play positive role for sloughing off dead parts of coralline algal thallus, although they have been regarded as those cells terminating filaments or having a function for removing harmful objects such as other algal spores by sloughing.