Amoeba proteus was exposed to a low concentration of methyl di-(β-chloroethyl) amine (MBA, a ‘nitrogen mustard’). Subsequent nuclear transfer was used to study the relative sensitivities of nucleus and cytoplasm to MBA. Nuclei were found to be 10 times as sensitive as cytoplasm. Exposure to MBA caused a short delay before the first division of the nucleus and a longer delay before the second division, the delay before the first division being more marked with exposure to LD100 or higher concentrations. The first cytoplasmic division was delayed after treatment but subsequent division showed little change. MBA caused many abnormalities in division. When cytoplasm was injured the nuclei became swollen or, with less severe damage, divided without subsequent cytoplasmic division. When only nuclear damage was present, such abnormalities as incomplete prophase, non-nucleate division, uneven division, and cytoplasmic fragmentation occurred.
- Copyright © 1956 by the Company of Biologists Ltd.