To clone the
kra-1 gene which might encode a nicotinic receptor associated NMDA receptor-like ion channel (Hideki Ando and Hiroaki Kagawa, in this issue),
mec-1 gene was chosen as the starting point for chromosome walking. 11 lambda clones crossreacted with 5 unique fragments from 2 Tc1 induced
mec-1 worms were mapped on the chromosome map LGV as was shown in the bottom. One of the clones; HK#9.1 was sensibly located on the position which was calculated by the average relation value between genetic and physical map. We started to RFLP experiment on gamma ray induced mutants to confirm the position of the
mec-1 gene by using candidate cosmid clones. International cooperation will accelerate to finish the jig saw puzzle. Tropomyosin gene cloning was nearly finished but still continuing by some unlucky (The worm gazette Vol.10 #3 1988). Any genomic library do not contained tropomyosin gene by some reason of sequence similarity to lambdoid phage. We have already cloned two genomic restriction fragments which contained 6/8 exons. By screening YAC library with one restriction fragment as a probe, '
tmy-1', tropomyosin gene was mapped on the left of
unc-54 LGI. The result was independently confirmed with a different approach by Larry Shriefer and Bob Waterston (in this issue). They are doing experiment on searching a candidate mutant of tropomyosin gene defect. Full length cDNA clone was also obtained from new cDNA library (kindly supplied by Barsted and Waterston). Complete cloning business shows the reason why the gene was not packed in a phage particle. [See Figure 1]