Fluorescence Microscopy and Autoradiography of Colchicine-induced Micronucleated Cells

Abstract

COLCHICINE inhibits mitosis in plant and animal cells¹. When colchicine-treated tissue-cultured cells are stained with acridine orange fluorochrome and viewed by fluorescence microscopy, an impressive result of its activity is seen as a morphological disorganization of the nuclei² and subsequent formation of micronucleated cells. X-irradiation causes a similar effect³. The origin of micronuclei may be accounted for either by fragmentation of the interphase nucleus⁴ or by formation from chromosomal material⁵. Results of a previous investigation⁶ favoured the chromosome-fragmentation hypothesis but did not exclude the nucleus-fragmentation hypothesis as an alternative pathway. The sequence of nuclear changes which followed colchicine-treatment of cells was examined by cytochemical staining procedures with acridine orange fluorochrome⁷: when stained preparations are viewed by fluorescence microscopy, DNA- and RNA-components of the cell fluoresce shades of green and red, respectively. The biochemical integrity of colchicine-induced micro-nucleated cells was explored by autoradiography with tritiated thymidine.