Worm Breeder's Gazette 9(2): 99

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.

Further Genetic Analyses of a Long Life-Span Mutant Strain

D. Friedman and T. Johnson

Last year we reported our early analyses of the long-lived mutant 
strains isolated in the DH26 background (fer-15(b26)) by Mike Klass.  
One of the longest-lived mutants, MK546 (age-1(hx546)), is also unc-31(
z1) IV, male sterile and exhibits a decreased brood size (Brd).  MK546 
was backcrossed to N2 males and the F2 were subcloned to the F5 in the 
first experiment and to the F15 in a repeat experiment to establish 
homozygous age-1 reisolate stocks.  age and unc do not cosegregate in 
the reisolates, nor is there a correlation between age and a decreased 
development rate (determined by measuring worm length) nor between age 
and the time at which 50% of the population is fecund.
However, further tests have shown that both fer-15 and brd 
cosegregate with age.  This is contrary to our initial report which we 
now believe to be incorrect based on the more complete repeat of the 
original experiment.  The segregation of age and brd is consistent 
with a single nuclear gene.  We have not, as yet, been able to 
separate the age or brd phenotypes conferred by the age-1 locus from 
fer-15.  We are now using both brd and fer as predictors of age in 
homozygous reisolate stocks due to the relative ease of assay.
Several complementation tests for life-span between the age (long-
life) locus of MK546 and the age loci of MK31 and MK542 (also isolated 
by Klass) suggest that age-1(hx546) fails to complement age(hx542), 
but does complement age(hx31) to yield F1 which display non-age (
normal) life-span, although we are still confirming this last result.  
Two complementation tests for brd suggest that MK546, MK542 and MK31 
are allelic for the locus.  Both the age and brd complementation data 
are consistent with observations by Paul Fitzpatrick showing that age 
in MK31 does not cosegregate with the brd and fer phenotypes also 
found in that strain.
The isolation of two new phenotypes (age and brd) tightly linked to 
fer-15 is unusual.  Several events could explain this linkage.  Models 
include mutations conferring a pleiotropic effect of the fer-15 locus, 
a polar Tc1 insertion and multiple tightly-linked mutational events or 
a chromosomal inversion.  We have excluded Tc1 as a causative agent 
because we observe no new band(s) after probing genomic DNA from both 
age and non-age stocks with pCe2002(Tc1).