title: Preapoptotic chromatin changes induced by ultraviolet B irradiation in human erythroleukemia K562 cells.
abstract: Exponentially growing human erythroleukemia K562 cells were permeabilized and the dose dependent decrease of DNA synthesis rate was measured after ultraviolet (UV B, 290 nm) irradiation. Cells were able to overcome 2 and 5 J/m2 UV doses, partial recovery was observed at 15 J/m2, while at high (25 J/m2) UV dose replicative DNA synthesis remained suppressed. K562 cells were subjected to synchronization prior to and after UV irradiation (24 J/m2) and 18 fractions were collected by centrifugal elutriation. Cell cycle analysis by flow cytometry did not show early apoptotic cells after UV irradiation. The gradual increase in DNA content typical for non-irradiated cells was contrasted by an early S phase block between 2.2 and 2.4 C-values after UV irradiation. Cell cycle dependent chromatin changes after ultraviolet irradiation were seen as a fine fibrillary network covering the mainly fibrous chromatin structures and incompletely folded primitive chromosomes. Based on observations after UV irradiation and on earlier results with cadmium treatment and gamma irradiation, we confirm that typical chromatin changes characteristic to genotoxic agents can be recognized and classified.
authors: Department of Microbial Biotechnology and Cell Biology, University of Debrecen, 1 Egyetem Square, Debrecen 4010, Hungary.
authors: Kinga
authors: K
authors: Ujvarosi
authors: Janos
authors: J
authors: Hunyadi
authors: Gabor
authors: G
authors: Nagy
authors: Imre
authors: I
authors: Pocsi
authors: Gaspar
authors: G
authors: Banfalvi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D016466:CHO Cells; D002843:Chromatin / Q000737:chemistry / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D004261:DNA Replication / Q000528:radiation effects; D005260:Female; D006801:Humans; D020014:K562 Cells; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000532:radiotherapy*; D014466:Ultraviolet Rays
chemical_list: D002843:Chromatin