Worm Breeder's Gazette 7(1): 64

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.

Use of Recombinant Inbred Strains in the Genetic Analysis of Lifespan

T.E. Johnson

Recombinant inbred (RI) strains have been generated from crosses of 
Bristol (N2) and Bergerac (Lyon) parental strains.  F1 hybrid progeny 
from this cross are isolated and allowed to self-fertilize.  Resultant 
F2 progeny are then individually isolated and allowed to self-
fertilize.  After 3-5 days, individual F3 offspring are isolated to 
new plates.  This procedure is repeated through 20 rounds of 
inbreeding, which leaves the genome homozygous to 1 part in 10+E6.
These RI strains show remarkable variations in length of life.  Mean 
lifespans vary from a low of near 11 days to a high of about 30 days.  
These differences are reproducible.  The large variation in lifespan (
both parental strains have lifespans of about 18 days) is presumably 
due to the recombination and subsequent homozygosis of allelic 
differences at many genetic loci.  There appear to be no major genes 
that affect lifespan segregating within this population.
Since several other genetic characteristics of the Bristol and 
Bergerac strains (e.g., uncoordinated behavior of Bergerac, lower 
pharyngeal pump rate of Bergerac, slower rate of larval development of 
Bergerac, and the presence of a ts gene causing either a Zyg or a Gon 
phenotype; Wood et al., 1980) are also segregating within these 
strains, we can estimate the correlations between these factors and 
lifespan.  For example, our studies, which are still in progress, show 
that about 10% of the variation in lifespan can be explained by the 
variation in pharyngeal pump rate.
We are now using these RI strains for selective breeding experiments 
designed to obtain longer lived strains of worms.