Effects of Several Sulfa- Compounds on Nuclear and Cell Division

Abstract

Roots of Allium cepa were immersed in 0.5% sul-fanilamide and 0.1% sulfadiazine, sulfaguanidine, sulfamer-azine, sulfapyridine, and sulfathiazole (above the max. solubility of these compounds in water at 20 [degree]C). There was an immediate cessation of visible root elongation in all treatments, but approx. half the roots of any bulb treated with sulfanilamide developed tumors within 48 hrs., owing to the enlargement of cortical cells in the morph. region of elongation. Similar tumors were formed in roots of one bulb immersed in sulfapyridine. The cytological results of treatment with sulfanilamide were essentially the same as previously reported. Normal-appearing mitosis continued throughout the 96 hrs. of treatment in a few cells. Disruption of the spindle mechanism resulted in tetraploidy, and binucleate cells resulted from the failure of cell-plate formation. Nuclei of irregular lobed outline were found, but no micronuclei were present. Mitosis was completely blocked in one series of treatments with sulfanilamide, and no tumor formation occurred. The other five sulfa- compounds induced essentially identical response in each exp. Although there was no visible elongation, mitosis continued throughout the 96 hrs. of treatment. Even though the chromosomes were shorter than in the controls, the degree of contraction was not so great as observed in sulfanilamide treatments. On return to water all roots resumed normal growth. The markedly different responses to sulfanilamide and to the other sulfa- compounds are possibly caused by the greater solubility in water of sulfanilamide.