EFFECTS OF HYPERGRAVITY ON THE ELONGATION AND MORPHOLOGY OF PROTONEMATA OF ADIANTUM-CAPILLUS-VENERIS

Elongation growth of protonemata of Adiantum capillus-veneris, which c an be controlled by light irradiation, was examined under acropetal an d basipetal hypergravity conditions (from -13 to +20 g) using a newly developed centrifugation equipment. Elongation of the protonemata unde r red light was inhibited by basipetal hypergravity at more than +15 g but was promoted by acropetal hypergravity from -5 to -8 g. Division of the protonemal cells that was induced by white light was inhibited under basipetal hypergravity at +20 g but was unaffected under acropet al hypergravity at -15 g. Upon exposure to continuous red light for 7 to 8 days, most of the protonemata grew as filamentous cells in the ab sence of a change in the normal gravitational force (control), but mor e than half of the protonemal cells were abnormal in terms of shape wh en maintained under hypergravity at +20 g.