**Recombination Accessibility and Genome Structure** MCB abstract

Graham Dellaire dellaire at odyssee.net
Sun Jul 27 20:44:33 EST 1997

Dear Colleagues,

To try to start the ball rolling I would like to post the following
abstract which is taken from my paper recently accepted and to appear in
this September's issue of Molecular Cellular Biology .  It is my hope that
all those that participate in the group could post abstracts of their
recently accepted manuscripts as well.  In this way GenStructure may
provide current and timely peer reviewed material for the benefit of all
its readership.  I look forward to reading _your_ work!

Best Regards,

G. Dellaire
Moderator GenStructure
======================abstract to follow================

Ectopic gene targeting exhibits a bimodal distribution of integration in
murine cells indicating both intra and interchromosomal sites are
accessible to the targeting vector. 

Dellaire, G., Lemieux, N., Belmaaza, A. and P. Chartrand.
(1997 In press: Mol. Cel. Biol., vol. 17, #9).


Ectopic gene targeting is an alternative outcome of the gene targeting
process in which the targeting vector acquires sequences from the genomic
target but proceeds to integrate elsewhere in the genome. Using two color
FISH analysis we have determined the integration sites of the gene
targeting vector with respect to the target locus in a murine fibroblast
cell line (LTA). We found that for ectopic gene targeting the distribution
of integration sites was bimodal, being either within 3 Mb of the target 
or on distinct chromosomes from the chromosome carrying the target 
locus. Both inter and intrachromosomal sites appeared to be equally 
accessible to the targeting vector with site specific variations.
Interestingly, interphase analysis indicated that vector sequences which
had integrated ectopically in other chromosomes than the target
co-localized with the target locus at a significant frequency as compared
to random unlinked loci. We propose that ectopic gene targeting could be
used to determine which chromosomal domains within the genome are
accessible to a given genetic locus. Thus, recombination access mapping
(RAM) may present a new paradigm for the analysis of DNA accessibility and
interaction within the genome 


| Graham Dellaire                    
| Division of Experimental Medicine  
| Dept of Medicine, McGill University

| e-mail: dellaire at odyssee.net        
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