title: [Rate of DNA synthesis and the size of replication units in cell culture of Drosophila melanogaster].
abstract: The rate of DNA replication and the size of replication units was examined by means of pulse-labeling with 3H-thymidine and DNA autoradiography in the chromsomes of Drosophila melanogaster  synchronized cells culture in vitro. The center-to-center distance between adjacent labeled section of DNA fibers was taken for a size of replication unit, i.e. replicon. DNA synthesis was revealed to start simultaneously in most replicons. The rate of elongation of labeled sections of DNA fibers is about 25 mu per hour (75 kb per hour). Taking into consideration bidirectinal DNA replication the rate of DNA replication per growing point is 12.5 mu per hour (38 kb per hour). The mean size of replicon is about 60 mu (130 kb) in cell culture of Drosophila melanogaster and most of these replicons vary from 20 to 80 mu. Calculation suggests that one replicon may consist of six chromomeres each being known to be formed by a segment of DNA molecular 10 mu long on average.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002875:Chromosomes / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D004261:DNA Replication; D004331:Drosophila melanogaster / Q000378:metabolism*; D005467:Floxuridine / Q000494:pharmacology; D008970:Molecular Weight; D014529:Uridine / Q000378:metabolism
chemical_list: D005467:Floxuridine; D004247:DNA; D014529:Uridine
vernacular_title: Opredelenie razmerov replikonov i skorosti replikatsii DNK v kletok Drosophila Melanogaster.