FLUORESCENCE STUDIES OF THE CHANGES 



UNDERGONE BY NUCLEOPROTEINS AND THEIR 



DERIVATIVES IN IRRADIATED CELLS 



M. N. MEI8SEL, E, M. BRUMBERU, T. M. KONDRATJEVA 



AND I. J. BARSKY 



Institute of Biophysics, Institute of Badiation and Physico-chemical Biology, 



Academy of Sciences of the U.S.S.K., Moscoiv, and Central Scieyxtific Research 



Institute of Medical Radiology, Leningrad, U.S.S.R. 



SUMMARY 



Radiation-induced changes in nucleoproteins, nucleic acids and nucleotides 

 in the cytoplasm and nuclei of living cells are described in the paper. These 

 changes are detected on preparations vitally fluorochromed with acridine dyes, 

 by fluorescent microscopy in the visible spectral region, as well as by an investi- 

 gation of the auto -fluorescence registered in the ultraviolet spectral region. 



The processes described reiDresent labilization and denaturation of DNA- 

 proteins, accinnulation of RNA and nucleotides in the cytoplasm, and changes 

 in theii" x^hysico -chemical properties which have an effect upon the character of 

 the fluorescence. The intensity and the spectrvim of ultraviolet fluorescence of 

 the cells in radiosensitive organs undergo considerable changes soon after X- 

 irradiation. 



Ultraviolet fluorescence microscopy aj)plied to the study of radiation damage 

 to cells yields, especially in combination with ultraviolet absorption microscopy 

 and fluorescence microscopy in the visible spectral region, new facts about the 

 state of cellular nucleoproteins, and their early and later changes due to radiation. 



The first reports of the use of fluorescence microscopy in radio- 

 biological studies appeared more than twenty years ago (Wels, 1938; 

 Hercik, 1939; Biebl, 1942). Considerable advances made in this subject 

 in the following twenty years extended its scope and led to a more 

 knowledgeable use of the technique in various branches of biology, in- 

 cluding radiobiology. Progress was facilitated firstly, by the introduc- 

 tion of fluorescent stains, fluorochromes, of low toxicity, suitable for 

 vital and supravital investigations; secondly, by the development of 

 fluorescence cytochemical methods, especially the cytochemistry of 

 nucleic acids (Meissel and Korchagin, 1952; Armstrong, 1956; Schiim- 

 melfeder et al., 1957; Bertalanffy and Bickis, 1956); and thirdly, by 

 considerable improvements in the apparatus permitting fluorescence 

 microscopy to be combined with phase contrast and ultraviolet absorp- 

 tion techniques (Brumberg, 1955; Haselmann and Wittekind, 1957). 

 In this respect special mention should be made of the procedure 



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