title: Ku-related antigens are associated with transcriptionally active loci in Chironomus polytene chromosomes.
abstract: Antigens of Chironomus reactive with human sera containing anti-Ku antibodies and also with specific antibodies to each Ku subunit were characterized by immunoblot analysis. Three main antigen species were identified in nuclear-enriched extracts from salivary gland cells of Chironomus thummi, ranging in Mr from 55000 to 67000. The nuclear localization of Ku-related antigens in the dipteran Chironomus was studied by immunofluorescent labeling in polytene chromosomes of the salivary glands. Balbiani rings, loci highly active in transcription, were found to be strongly labeled by anti-Ku antibodies. Sugar-induced changes in the activity of the Balbiani ring genes were accompanied by the redistribution of Ku-related antigens as visualized by their absence in regressed Balbiani ring loci, and continued presence only in those that were transcriptionally active. A drastic change in the distribution of Ku-related antigens was also observed when C. thummi larvae underwent heat treatment as the immunofluorescent staining was restricted to previously described heat shock puffs. Anti-Ku sera reacted in addition with several chromosomal bands in which the presence of RNA polymerase II was also immunologically detected. The results show that Chironomus antigens reactive with anti-Ku antibodies are related to transcription in polytene chromosomes.
authors.affiliation: Centro de Investigaciones Biológicas (CSIC), Velázquez 144, E-28006 Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Gorab
authors.forename: L M
authors.initials: LM
authors.lastname: Botella
authors.forename: J P
authors.initials: JP
authors.lastname: Quinn
authors.forename: J M
authors.initials: JM
authors.lastname: Amabis
authors.forename: J L
authors.initials: JL
authors.lastname: Díez
mesh_terms: D000438:Alcohols / Q000737:chemistry; D000818:Animals; D034961:Antigens, Nuclear; D002683:Chironomidae / Q000235:genetics*; D002874:Chromosome Mapping; D002875:Chromosomes / Q000276:immunology*; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D005786:Gene Expression Regulation; D006358:Hot Temperature; D006801:Humans; D000072200:Ku Autoantigen; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology*; D012319:RNA Polymerase II / Q000235:genetics; D011817:Rabbits; D012303:Ring Chromosomes; D014158:Transcription, Genetic
chemical_list: D000438:Alcohols; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D012319:RNA Polymerase II; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen