BRIEF INCUBATION OF GAMETANGIA-BEARING CAPS IN ANTIBIOTICS ELIMINATESBRANCHING IN PROGENY OF ACETABULARIA-ACETABULUM (CHLOROPHYTA)

Branching of the stalk of Acetabularia acetabulum L. (Silva) was inves tigated by inbreeding and by a brief treatment of gamelangia with a va riety of antibiotics. The position of the branch along the stalk varie d, implying that branching was not restricted to any one time in devel opment (base is oldest and apex is youngest). The branching phenotype was not inherited in Mendelian fashion. Although three microscopic str uctures (''bubbles,'' ''pustules,'' and ''scars'') occurred on the sta lks of cells that had branched, these structures were not statisticall y correlated with branching in the population (n = 699 cells). However , brief treatment of gametangia with a new antibiotic mixture did elim inate all macro- and microscopic structures associated with branching of the stalk in the subsequent generation. We could not fulfill Koch's postulates or provide clear evidence for the pathogenic nature of cel l branching. Our brief antibiotic treatment of gametangia of Acetabula ria acetabulum was rapid, had no adverse effects, and virtually elimin ated branching (and any potential pathogens) from laboratory cultures in the subsequent generations. Our method allows biochemical and molec ular analyses to proceed uncomplicated by the possible presence of oth er organisms and provides a clean baseline for the future selection of mutations that may induce heritable branching.