title: The association of Brahma with the Balbiani ring 1 gene   of   Chironomus tentans studied by immunoelectron  microscopy and chromatin immunoprecipitation.
abstract: Many steps of gene expression take place during transcription, and important functional information can thus be obtained by determining the distribution of specific factors along a transcribed gene. The Balbiani ring (BR) genes of the dipteran Chironomus tentans constitute a unique system for mapping the association of specific factors along a eukaryotic gene using immuno-electron microscopy (immuno-EM). The chromatin immunoprecipitation (ChIP) technique has provided an alternative, more general method for studying the association of proteins with specific genomic sequences. The immuno-EM and the ChIP methods suffer from different limitations, and thus a combination of both is advantageous. We have established optimal conditions for ChIP on chromatin extracted from the salivary glands of C. tentans , and we have analyzed the association of the SWI/SNF chromatin remodelling factor Brahma (Brm) with the BR1 gene by combined immuno-EM and ChIP. We show that Brm is not restricted to the promoter of the BR1 gene but is also associated with sequences in the middle and distal portions of the gene, which suggests that Brm has additional roles apart from regulating transcription initiation.
authors.affiliation: Department of Molecular Biology & Functional Genomics, Wenner-Gren Institute, Stockholm University, SE-10691 Stockholm, Sweden
authors.forename: S Calado
authors.initials: SC
authors.lastname: Botelho
authors.forename: A
authors.initials: A
authors.lastname: Tyagi
authors.forename: V
authors.initials: V
authors.lastname: Hessle
authors.forename: A K Ostlund
authors.initials: AK
authors.lastname: Farrants
authors.forename: N
authors.initials: N
authors.lastname: Visa