Worm Breeder's Gazette 2(2): 8

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.

A C. elegans Dumpy Roller Mutant with Early Temperature-sensitive Periods

R. Ouazana, J. Brun

The temperature-sensitive mutant ts L 48 was obtained in the F3 
progeny of worms of the Bergerac strain (NIGON 1949) mutagenized at 
the fourth larval stage with EMS, 0.5 M.  This mutant develops with 
wild behavior and wild size at 17 C (the permissive temperature), but 
displays roller and dumpy phenotypes when grown at 22 C.  At this 
restrictive temperature, ts L 48 rotates only to the left.
Genetic studies prove that ts L 48 carries a single autosomal 
recessive mutation (or two very linked mutations without detectable 
recombination).  The fact that a single pleitropic mutation can lead 
to both roller and dumpy phenotypes was already observed in C.  
elegans, Bristol, by BRENNER (1974), with non-temperature-sensitive 
mutants (alleles of dpy-2 gene on L.G.  II).
The maternal or non-maternal inheritance was determined by the A and 
B tests (HIRSH and col.1976).  Both prove non-maternal inheritance of 
the two temperature-sensitive phenotypes.  This was not surprising 
according to the temperature sensitive periods, (see below) and 
indicates that roller and dumpy phenotypes of ts L 48 are not due to 
contribution of an oocyte component.
The temperature-sensitive periods (TSP) of the two ts L 48 
phenotypes were inferred from schift-up and schift-down experiments.  
A TSP is delineated by the earliest time of shift-down (from 22 C to 
17 C) at which the mutant phenotype is observed and the latest time of 
shift-up at which mutant phenotype occurs.
The TSP of the roller phenotype begins a few hours after hatching.  
It is entirely situated in the first larval stage (L1), from 18 hrs to 
25 hrs of development at 22 C after fertilized eggs deposition).
The TSP of the dumpy phenotype is more extended.  It includes later 
L1 stage, all the L2 stage, and the beginning of the L3 stage (from 18 
hrs to 42 hrs of development at 22 C, after fertilized eggs deposition)
ts L 48 size growth curves at 17 C and 22 C, demonstrate that 
dumpiness expression starts at the beginning of the L3 stage, near the 
end of the dumpy phenotype TSP.
Regarding roller phenotype, it never be expressed until the adult 
The study of this mutant agrees with the conception that cuticular 
alterations can lead both to roller and dumpy phenotypes.  
Nevertheless, in contrast with the observations of Higgins and Hirsh (
1977) on the temperature-sensitive roller mutant ts B 238, in C.  
elegans Bergerac - for ts L 48 at least - the roller TSP needs not 
coincide with the time of formation of the adult cuticule but may be 
very earlier.