CHROMIUM-INDUCED SEXUAL REPRODUCTION GIVES RISE TO A CR-TOLERANT PROGENY IN SCENEDESMUS-ACUTUS

A clonal population of Scenedesmus acutus was treated for 3 months wit h 1 mg/liter Cr(VI) and then returned to Cr-free medium. After several months, the cells were treated with different Cr concentrations and t hen subjected to a series of morphological observations and metabolic tests. The results, compared with those obtained with a normal cell po pulation treated in the same way, demonstrate that the progeny of alga e subjected to the prolonged Cr treatment has acquired tolerance to th e metal, as it can survive and grow in the presence of Cr concentratio ns that are lethal to normal cells. An ultrastructural description of gametes and zygotes is also given. (C) 1995 Academic Press, Inc.