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.
contigs= 515 mean contig size= 141kb 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. CHROMOSOMAL CONTIG MAPS 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 reproducibility}