Worm Breeder's Gazette 11(4): 27a

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Title unknown.

Authors unknown.

The physical region spanning unc-30 to dpy-4 has recently been 
assembled from 10 constituent cosmid contigs by the use of YACs.  By 
considering the sizes of the YACs involved (determined from PFGs) and 
the pattern of cosmids to which they hybridize, it is possible to 
calculate that the distance covered is 2350+/-400kb.  However, only 
480kb of this is contained in characterized cosmids.  Continuing 
rightwards from dpy-4, a phage which contains the tRNA(trp) gene sup-
24 identifies a 470kb YAC which does not hit any cosmids at all.  This 
means there is approximately 3000kb of the genome for which the 
attendant set of cosmids amounts to less than 500kb, or 17%.
These contigs were assembled in order to find the tra-3 gene, at a 
time when it was believed that less than 10 Mb of genomic DNA (
assuming 100Mb genome size) was not yet contained in the cosmid map.  
There are therefore either few such regions in the genome or this was 
an underestimate.  Considering that many cosmid contigs were shown to 
overlap by a small region when YAC hybridization data juxtaposed them, 
and that in the general case of YAC bridged gaps estimates of the size 
of the gaps are small, it is more likely that there are few such 
regions.  Nonetheless, it should be borne in mind that on the physical 
map, all YAC-bridged gaps are drawn arbitrarily as 5 HindIII sites 
long but the largest YAC-bridged gap encountered in the tra-3 region 
was approximately 300kb.