Variations in Morphology and DNA Distribution Among Chloroplasts in Mature Germling Cell of Bryopsis plumosa (Hudson) C. Ag. (Chlorophyceae)

Fluorescence microscopy with the DNA-specific fluorochrome 4',6-diamidino-2-phenylindole (DAPI) revealed the presence of many intensely fluorescing areas around the giant primary nucleus in the mature germling cell of the green alga Bryopsis plumosa. Each of the fluorescent areas was irregular in shape and larger and brighter than the nucleoids scattered uniformly within the chloroplasts which could ordinarily be seen in the germling cell. Near the primary nucleus there were 40 or more small lenticular chloroplasts. They were morphologically different from the usual fusiform chloroplasts and were generally poor in starch and often lacked pyrenoids. The intensely fluorescing areas were always associated with these small perinuclear chloroplasts, implying that they were nucleoids of these chloroplasts. Our results indicate that, among the chloroplasts in the germling cell of B. plumosa, those located near the giant primary nucleus differ from others in morphology and also in DNA distribution.