Biological and electron microscopic changes in gamma radiated Cryptococcus neoformans

Samples ofCryptococcus neoformans were irradiated with various doses of gamma radiation. The relatively low doses, 1–5 × 10⁴ rads, resulted in no obvious effect on the fine structure of the cells but did seriously prevent a large proportion of the organisms from reproducing on agar. When subjected to doses of 1 × 10⁶ rads virtually all the organisms lost their ability to reproduce. When such samples were examined in the electron microcsope, almost all the cells were found to have lost their capsules whereas other aspects of their fine structure remained apparently normal.This work was supported by the Sandy Schneider Memorial Fund and by the United Hospital Fund.