Worm Breeder's Gazette 9(2): 98

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.

Developmental Effects of Loci Lengthening Life-Span

T. Johnson, B. Conley, and M. Bryant

Both recombinant inbred (RI) lines and single gene mutants (see 
other abstracts in this issue) have been produced which have dramatic 
changes in life-span.  Stocks average a 60% increase in mean and 
maximal life-span.  We have been interested in knowing whether these 
changes also result in a change in developmental events (length of the 
embryonic period, timing of cell divisions, rate of larval growth, 
timing of larval molts) or in the length of the reproductive period.
We have assayed the length of the embryonic period by isolating 
individual eggs at the 2-cell stage and transferring these eggs to 
incubation chambers at 16 C (chosen for convenience of monitoring).  
About 20 hours later the eggs hatch.  We find no change in the length 
of this period in either the RI lines or in age-1(hx542) or age-1(
hx546).  Surprisingly, N2 seems to take about 1 hour longer to 
complete this phase than any other stock analyzed, including Bergerac 
We see variation among the RI lines in the rate of larval growth, in 
the timing of larval molts, and in the time from hatch to 50% adult 
fecundity.  These variations do not seem to correlate with the adult 
life-span but limited numbers of stocks have been assayed as of yet 
and we remain unclear about our level of statistical significance.  It 
is clear that both(?) age-1 alleles are without effect on any aspect 
of larval development rate.
There is marginal variation in the length of the reproductive period 
and in the total fecundity, among the RI lines.  The quantitative 
variations in total fecundity showed statistically significant 
correlations with the length of life in one repeat which has not yet 
been confirmed.  There is no correlation between the length of the 
fecund period and life-extension.  For the age-1 locus, there is a 
significant reduction in total brood size but no significant change in 
the temporal distribution of progeny production, after normalizing to 
total brood size.  As always, we welcome helpful and provocative 
suggestions of additional questions to ask and directions to proceed.