Changes in alkaline band formation and calcification of corticated charophyte Chara globularis

Chika Kawahata, Masumi Yamamuro, Yoshihiro Shiraiwa

Calcification by charophytes improves the quality of water, although most studies on calcification have only examined ecorticate species. We investigated the formation and relationship of alkalines and acids with regard to calcification on internodal cells in Chara corallina, an ecorticate species, and Chara globularis, a corticate species. We observed that alkaline and acidic areas with distinct banding patterns form on the internodal cells of C. corallina. The entire periphery of internodal cells was alkalized, and no distinct acidic area developed in C. globularis. By electron microscopy of these internodal cells, the calcified areas occurred primarily in alkaline areas with a banding pattern in C. coralline. However, phenomenon also occurred homogeneously inside of the entire cortex and cell wall in C. globularis. We also investigated the formation and relatiohship of alkalines and acids with regard to calcification on internodal cells of various ages from a single thallus of C. globularis. For internodal cells of C. globularis, a uniform calcified area lay between the cell wall and cortex on all cells, irrespective of age. In contrast, young cells bore an alkaline area that was uniform and widespread throughout their entire periphery, but the alkaline area in older cells was split into smaller segments in a banding pattern. Acidic areas were absent in young cells. These results indicate that the mechanisms by which alkaline and acid areas form differ in the presence and absence of cortex and between species.