*Cambridge Lab #Department of Molecular Biology JICPSR Massachusetts General Hospital Colney Lane Boston, MA 02114 Norwich USA NR4 7UH UK
The combination of the CIC library, the increased marker coverage and a few successful walking experiments have resulted in chromosome 4 being covered by just 15 YAC contigs (Schmidt, West, Dean). Chromosome 5 is currently covered by 35-40 contigs (Schmidt, Love, Z. Lenehan, Dean) after having used over 100 markers on 4 YAC libraries. Chromosome 2 (Goodman lab) is covered by about 40 contigs for a total distance of about 17Mb. The largest contig on chromosome 2, constructed in part using YAC end probes, is ~ 3.2Mb covering ~ 5.7cM. A similar level of coverage has been achieved for chromosomes 1 (Ecker lab). Cosmid contigs from the Goodman laboratory and EST clones are also being integrated into the chromosome 2, 4, and 5 YAC contigs. Efforts are continuing to generate a 1.5Mb cosmid contig (Bancroft, Love, Cobbett, Goodman and Dean) covering the region of chromosome 4 being sequenced as part of the EC ESSA programme (co- ordinated by Mike Bevan, Norwich). Currently 9 cosmid contigs covering 730kb have been restriction mapped and distributed to participating laboratories. Joining of these contigs will require alternative strategies due to sequences within the gaps being repetitive or underrepresented in the cosmid libraries being screened. Strategies based on YAC subclones, rather than cosmids, providing the sequencing templates for the next phase of the genomic sequencing project are being investigated (Bancroft). On a smaller scale a ~800kb contig on chromosome 2 is being sequenced using the multiplex method (Goodman lab).