Mitotic Acceleration Induced in Grasshopper Neuroblasts by Small Doses of Monochromatic Ultraviolet Radiation

Abstract

Abstract—Neuroblasts of the grasshopper, Chortophaga viridifasciata (DeGeer), in culture were exposed to 4–15 J/m2 of monochromatic ultraviolet radiation in middle prophase and timed to prometaphase (breakdown of the nuclear membrane). At wavelengths 265 and 280 nm the times recorded for the treated cells were significantly less than those for the matched control cells. Wavelength 225 nm produced neither significant acceleration nor deceleration of mitotic rate. Evidence from the present experiment does not implicate any particular chromophore in this response, though similar results of a previous microbeam study of neuroblasts point to the nucleic acid or protein of the nucleolus as the possible effective material.