Worm Breeder's Gazette 11(1): 39

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.

Identification of Tc1s Near emb-5 Gene

Kiyoji Nishiwaki and Johji Miwa

Temperature-sensitive maternal effect mutations in the emb-5 gene (1)
show premature second E cell division and abnormal gastrulation at 
nonpermissive temperature.  Embryos arrest as balls of cells without 
normal morphogenesis (2).  Understanding of the emb-5 gene function at 
the molecular level should provide a good insight into the mechanism 
of morphogenesis in animal development.  We are trying to clone the 
emb-5 gene by chromosome walking from Tc1s linked to emb-5 and 
transformation experiments.  We have genetically mapped the emb-5 gene 
and located it between unc-79 and dpy-17 on linkage group III.  To 
identify Tc1s near the emb-5 gene in Bergerac BO or TR679, we have 
outcrossed these strains ten times to Bristol N2-derived emb-5 mutant 
strains doubly marked with unc-79 and dpy-17 or singly with unc-79 and 
constructed strains with Bristol background except for the region 
around emb-5.  Southern analysis of Tc1-containing restriction 
fragments for the constructed strains and their parental strains has 
revealed two Bergerac-associated Tc1s.  Three factor mapping has 
assigned one fragment about 0.28 mu to the left of the emb-5 gene and 
the other about 0.03 mu to the right.  We also found one TR679-
associated Tc1-containing fragment closely linked to emb-5, although 
its map position has not been accurately determined.  Using the 
flanking DNAs of the two Bergerac-associated Tc1s as probes, we have 
isolated EMBL3 N2 genomic clones.  Phage clones corresponding to these 
Tc1 flanking sequences have been sent to Drs.  John Sulston and Alan 
Coulson, Cambridge, England, for physical mapping.