X-Message-Number: 17825
Date: Wed, 31 Oct 2001 19:00:55 -0800 (PST)
From: Doug Skrecky <>
Subject: 49'th update on fly longevity experiments
This is the 49'th update of my fly longevity experiments. All bottles
contain 1/4 tsp citric acid as a standard additive. Recorded average
temperature during the experiment was 25.6 C. I will be reporting the
temperatures in future runs, since fly longevity is known to decrease with
higher temperatures. Thus if abnormally long maximum survivals are found,
such as the 118 days from a previous experiment, then this could be
directly compared with the best results at similar temperatures that have
been obtained in published experiments using the same substrain of
drosophila.
In future runs I will continue to examine targeted supplements such as
antivirals, or those which may protect against motor neuron degeneration.
I will also be trying random testing of a wide variety of supplements as
well, in a search for the unexpected. To date, with the exception of
reducing the temperature (and metabolic rate) of flies, no intervention
has significantly increased maximum fly survival. Caloric restriction,
which has worked well in mice, and with some limited success in rats, is
completely without effect in flies. No supplements have convincingly
increased longevity by more than about 20%. Over a hundred supplement
tests in flies have been published, which is about as much as my own
home grown fly experiments have searched.
Conflicting results have been obtained in some published experiments,
which have been attributed to pathogens covertly infecting some
experiments. Under clean room conditions motor neuron degeneration has
been found to be the major determining factor of fly longevity. Drosophila
is thus an animal model of Lou Gehrig's disease (Proc. Natl. Acad. Sci.
USA 92: 8533-8534 September 1995).
In my own less than sterile experiments, I believe virus induced
mortality to be a major factor in fly longevity in the summer, unless
freeze concentrated elderberry nectar is used in place of water. During
the winter usually the last few surviving flies have lost their ability to
fly before expiring, so viral infections are less of a factor in maximum
fly mortality. My eventual goal is to reduce viral load enough, so that it
no longer has a significant effect on mortality. My experiments will then
become a straight forward slugging match against motor neuron disease.
Thus far the most powerful protectant against what I believe to be viral
mediated death has been freeze concentrated Knudsen Elderberry nectar. In
a repeat of the experiment which yielded a 118 day maximum survival during
the winter, during the summer survival was 32% at 49 days, and all flies
had lost the ability to fly. Maximum survival was 54 days, or less than
half of that measured in the winter.
The strong color (and expense) of this juice has rendered it less than
completely desirable for use as a water replacement. However if no more
acceptible alternative comes to light in the next dozen runs, then it will
become a standard water replacement.
In the current experiment I test the effect of a variety of fibers on
fly mortality. No benefit was seen, and in the case of xanthan gum the
reduction in longevity appears to be significant. The next run tests other
dosages of some of these fibers.
Run #49 Percent Survival on Day
supplement 4 8 13 18 23 30 35 41 46 51
________________________________________________
control 97 63 63 56 41 22 13 6 0 -
agar-agar 1 tsp 100 69 52 52 48 24 17 14 3 0
arabica gum 1 tsp 100 73 47 40 20 7 0 - - -
corn bran 1 tsp 91 64 64 64 55 27 18 0 - -
guar gum 1 tsp 100 59 55 45 31 3 0 - - -
pectin 1 tsp 93 56 41 30 30 7 0 - - -
psyllium 1 tsp 80 56 52 44 20 4 0 - - -
xanthan gum 1 tsp 44 13 13 6 0 - - - - -
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