Worm Breeder's Gazette 10(2): 93

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.

The Genome Map

Alan Coulson, John Sulston, Yuji Kohara, Donna Albertson and Rita Fishpool

mean contig size= 
Linkage of the existing cosmid contigs by means of yeast artificial 
chromosomes (YACs) is proceeding steadily.  Two grids have been 
prepared: one of 2700 YACs, the other of 2000 representative lorist 
cosmids.  Since the YAC and lorist vectors do not cross-hybridize, we 
are able to probe back and forth between the two grids.  The 
proportion of the genome in identified contigs has advanced to 40%, 
and is depicted (in a somewhat imaginative fashion) on the chromosomal 
contig maps below.
In light of some recent comments, we want to emphasize two points 
about the mapping of newly cloned genes.  First, the optimal mapping 
strategy is still to send your clone to the MRC, regardless of whether 
or not you are probing YAC filters with it.  Provided the clone falls 
into a mapped region, fingerprinting provides a secure assignment, 
regardless of dispersed repeat sequences, and also positions the clone 
more accurately than is possible by hybridization alone.  Second, 
although the existence and position of your clone become public, the 
clone itself (and any contiguous clones) do not.  Enquiries about the 
region immediately adjacent to your clone are invariably directed back 
to you before we send out any material.
The genome map data has become sufficiently extensive and complex 
that a pictorial overview may now be useful.  The accompanying maps 
are a first attempt; they are an optimized computation based on all 
the data - genetic, in situ, and contig - that we have at present.  
Horizontal lines delineate those contigs that have been positioned on 
the chromosomes to date.  The long range ordering, down to 15-20%, is 
likely to be secure; the short range ordering, except for that defined 
by markers on the line of the genetic map, is arbitrary.  Nevertheless,
the maps should give a reasonably accurate impression of the regions 
of the genome that have been covered so far.  Other regions are, of 
course, likely to be covered also, but we have no means of knowing 
until new markers or further linkage reveal them.  Please ask us for 
more information about areas that particularly interest you, and tell 
us about any features of the map with which you disagree.  Please also 
give us official names for all those upper case (i.e.  temporary) 
genetic markers.
For practical reasons, we have chosen to plot the data on a metric 
defined by in situ hybridization, rather than on a genetic metric (in 
which the clusters are highly compressed, because of suppression of 
recombination - see CSH meeting abstracts, 1988, p12).  However, it is 
interesting that even on this physical metric there is a lot of 
unassigned space in the arms.  J. S.  bets R. W.  that there really is 
plenty of gene-poor DNA out there; R. W.  bets J. S.  that it's some 
kind of artefact.  We shall see.
{maps excluded due to poor