The recombinant phage RW70-4 (obtained from Bob Waterston) carries 4- 5 kb of Bristol (N2) genomic sequence in addition to the 1 kb 5S DNA repeat. We previously reported that the 2.2 kb BamHI fragment immediately flanking this 5S DNA cluster is shifted to a pair of BamHI fragments (2.5 and 2.6 kb) in the Bergerac (BO) genome. This RFLD was shown to be loosely linked to
dpy-11(V).We have left-right positioned this RFLD with respect to several linkage group V markers as shown below. The results to date confirm the linkage group V assignment and place this RFLD to the right of
unc-76. This correlates well with the in situ hybridization results placing the 5S RNA gene cluster towards the end of the chromosome (D. Albertson EMBO J. 3
p1227-1234). [See Figure 1] While constructing the recombinant strains to complete these mapping experiments (still in progress), we noticed a reduction in the recombination distance separating
dpy-21 and
unc-51 in the N2/BO heterozygote as compared to the N2/N2 heterozygote (p=0.06 and 0.09 respectively). All other distances were essentially identical (ie:
unc-76 ,
dpy-21). The sample size is not yet sufficient to lend statistical significance to this reduction and we are repeating the experiment anticipating that this may reflect a small rearrangement in this region of the BO genome relative to the N2 standard. Such a rearrangement may be related to the RFLD we have identified.