From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Sun Sep 09 2001 - 11:34:01 MDT
This is the 46'th update of my fly longevity experiments. All bottles
contain 1/4 tsp citric acid as a standard additive, except lemon and lime
juice bottles, which already contain citric acid. Additional potassium has
improved survival in a published experiment, and according to my last
update, it also does appear to improve survival when acetic acid is used
as an additive.
Both lemon, and lime can induce phototoxic reactions, so it is perhaps
not too surprising that they reduce survival. The current results strongly
suggest that potassium does not aid survival in citric acid treated flies.
The tartrate salt in contrast appears to be quite toxic. I had earlier
found tartaric acid itself to be toxic. It is possible that current fly
food batches may have an increased potassium content. If so this could
account for the null result with potassium.
During the summer months longevity decreases. For this experiment
average temperature was 25 C. The limiting factor in fly survival under
optimal conditions is known to be due to motor neuron degeneration.
However few of the flies in the current experiment lost the ability to fly
before expiring, so some other factor is responsible for their deaths.
Acid addition prevents molds and bacteria from inducing visible changes to
the fly food. As a result I doubt that these pathogens are responsible for
the early mortality. The literature is surprisingly sparce it its
examination of other causes of fly mortality. However it is apparent that
pathogens are a factor in published experiments. The experimental group
headed Dr Harold Massie has duplicated a number of experiments that found
large increases in survival with certain additives, and consistently
obtained null results under clean room conditions. Massie himself
attributed these contradictory results to the confounding effects of
pathogens. I believe the most likely explanation of the early deaths my
own experiments are now experiencing is due to viral infections. Acids
would not affect most of these, and flies are known to harbor a wide
variety iof viruses. It is intriguing that death due to pathogens in aged
humans is almost exclusively from viral infections. This is how one of my
own grandmothers expired.
Grape skins are known to exert an antiviral effect. This may account
for the my own past positive results with grape juice, as well as grape
containing elderberry juice. In the next run I will further investigate
these.
Run #46 Percent Survival on Day
supplement 4 9 14 19 25 30 34 39 44 49 56 61 67
___________________________________________________________
control 95 90 85 80 45 35 30 10 10 10 5 5 0
lemon juice 92 42 17 17 8 8 0 - - - - - -
lime juice 77 15 8 0 - - - - - - - - -
KHCO3 1/64 tsp 100 75 50 42 25 17 17 0 - - - - -
KHCO3 1/32 tsp 100 89 56 56 22 22 22 11 0 - - - -
KCL 1/64 tsp 92 83 58 50 33 25 25 9 9 0 - - -
KCL 1/32 tsp 100 81 69 56 44 44 19 13 6 0 - - -
K tartrate 1/32 tsp 67 42 25 8 8 8 7 7 0 - - - -
K tartrate 1/64 tsp 80 60 33 20 7 7 7 7 7 0 - - -
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 08:10:26 MST