Worm Breeder's Gazette 13(5): 80 (February 1, 1995)
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.
Dept. of Biology, Univ. of Miami, Coral Gables, FL 33124
We have isolated several mutants exhibiting increased life spans by
exposing EMS-treated mutants of C. elegans to heat shocks, and selecting
among survivors. It has previously been recognized that strains of
organisms exhibiting increased life spans are more resistant to various
stresses (Service, 1987; Partridge and Fowler, 1992). Our particular
selection method is based on an observation made after Hurricane Andrew:
power went out in the middle of an experiment comparing life expectancy of
the age-1 mutant and control strain. The life expectancy of the control
strain was decreased significantly, while that of the age-1 mutant was not
as affected, leading to a greatly increased relative life span for the
age-1 mutant. This result was shared informally with others at the 1993
meeting of the Gerontological Society of America. We presumed that some
other mutants exhibiting increased life expectancy might share this
characteristic of heat shock resistance.
F2, F3, and F4 progeny from EMS-treated (Brenner, 1974)
N2 were exposed to up to 4 rounds of heat shock over a 3-week period.
Each heat shock was 38-40 degrees C. for 2-3 hrs. The animals were
otherwise maintained at 20 degrees C. Most of the nematodes were killed
by the heat shocks, allowing for a smaller population of survivors to be
examined for life span. Worms that survived the heat shocks were
transferred to fresh plates (1 worm/plate). Life spans were determined for
progeny of each of these selected mutants. Several of the mutants
showed significant, 10-50% increases in mean life span. Males may exhibit
a greater increase in life span than hermaphrodites for one or two of the
new, life-extending mutants. We have begun complementation tests with the
known age-extending mutant, age-1, and hope to do complementations with
the dauer (Kenyon et al, 1993) and sperm defective mutants (Van Vorhies,
1992) which also are known to extend life span.
We conclude that heat shock can be used as a selection mechanism to
enrich for animals exhibiting life-span extension form among a mutant
population of nematodes. The effort involved in selecting for such
mutants is greatly reduced from that of Klass, who generated the age-1
mutation (analyzed by Johnson and aco-workers) by searching among 8,000
mutants.
We thank the CGC and Tom Johnson for strains of C. elegans, and the
American Federation for Aging Research for grant
support.