Worm Breeder's Gazette 11(4): 50

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.

Mutations in the dpy-13 Collagen Gene

N. von Mende and D.L. Riddle

The dpy-13 collagen gene was cloned by Tc1 tagging (von Mende, Bird, 
Albert, and Riddle, Cell 55:567-576, 1988).  At least some other dumpy 
genes also encode cuticle collagens (e.g., dpy-2 and dpy-10; Park and 
Kramer, J.  Mol.  Biol.  211:395-406, 1990), so this mutant class may 
be a rich resource for collagen structure-function analyses.  We 
determined eight dpy-13 mutant sequences (five EMS-induced; three Tc1 
insertions) by analyzing clones of PCR-amplified mutant DNA.  We also 
measured body dimensions to quantify the mutant phenotypes.
Two of the Tc1 insertion mutations, m399 and m400, are at the same 
site in exon 2, AACT...Tc1...ATGT, but the elements are in opposite 
orientations.  The third Tc1 insertion, m401, is in the TATA box of 
the putative promoter.
The reference allele, e184, is semi-dominant and it is a 36 basepair,
in-frame deletion affecting the first gly-X-Y domain, shortening it 
from (gly-X-Y)10 to (gly-X-Y)6.  The e510 allele is also slightly 
semidominant, and it has a G to A (gly127 to glu) change within the 
short region that is deleted in e184.  These mutant collagens 
apparently assemble with normal collagen to shorten body length in 
heterozygotes.  The e225 allele, on the other hand, is the least dumpy 
of the mutant set, and it is recessive.  It has a G to A (gly205 to 
glu) change in the region encoding the third gly-X-Y segment.  We 
conclude that the e225 protein has residual function, but may not 
interfere with normal collagen function, as do e184 and e510.  
The recessive e458 allele is a 673 base-pair deletion ending 
precisely at the TAA termination codon.  It deletes all of the gly-X-Y 
coding regions, and must therefore be a null allele.  The e458 
homozygotes are like the Tc1 insertion mutants in body shape.  They 
are not as short as e184, but they are significantly fatter.  Finally, 
the e488 allele has a G to A change at the first position in intron 1. 
This mutation presumably prevents normal splicing.  This seems not to 
be a null mutant, because the e488 homozygotes are as short as e184 
homozygotes (0.6 mm at the L4 to adult molt), in comparison with null 
mutants that are about 0.7 mm long as they enter the molt.