X-Message-Number: 23924
Date: Sun, 18 Apr 2004 12:20:44 -0700 (PDT)
From: Doug Skrecky <>
Subject: 133'rd update on fly longevity experiments
This is the 133'nd update of my fly longevity experiments. Average
temperature was 20.7 C during this run. Estimated maximal longevity using
the formula (363 - T*11.2) is 131 days.
Here I take a look a various different methods of black tea
preparation. In addition to adding the blended leaves directly to the fly
food, I also created both normal hot,and as well as cold water extracts
of tea leaves. Since the cold extracts were very dilute I continued the
cold extractions over-night in a fridge. The hot extracts were merely
stored as is in the fridge over-night. I also look at some different types
of seaweed.
Although the tea leaves themselves improved day 70 survival, none of
the leaf extracts offered any advantage at this time point. This
contradicts my previous results. After looking through the published
literature one explanation suggested itself. The survival improving effect
of black tea on drosophila has been ascribed to the presence of a
"volatile" iron chelator. If this is the case, then it is possible that
this may have evaporated during over-night storage of the tea extracts.
I'll have to take a second look at this variable in future.
Of the seaweeds, nori appeared to be modestly beneficial, while high
dose wakame turned out to be unexpectedly toxic.
Run #133 Percent Survival on Day
supplement 20 27 36 47 56 63 70 78 84 88 94 100 105
____________________________________________________________________
control one 82 82 75 54 32 14 7 4 4 4 4 0 -
control two 97 97 83 64 42 17 11 6 3 0 - - -
nori 1/2 tsp 95 79 63 37 21 21 16 11 5 5 5 5 0
nori 2 tsp 95 95 70 55 40 30 30 15 5 5 5 0 -
black tea leaves 1/2 tsp 88 82 77 65 41 41 29 12 0 - - - -
black tea leaves 2 tsp 94 94 77 77 41 29 12 6 6 0 - - -
",hot extract 2 bags/L 93 90 83 55 31 17 3 3 3 3 0 - -
",hot extract 10 bags/L 72 61 61 23 11 0 - - - - - - -
",cold extract 2 bags/L 96 91 87 52 13 13 4 4 0 - - - -
",cold extract 10 bags/L 84 79 63 42 5 5 5 0 - - - - -
",cold, then heated 2 bags 96 92 71 67 29 13 8 4 4 4 4 0 -
",cold, then heated 10 bags 96 96 93 63 52 26 7 4 4 4 0 - -
wakame 1/2 tsp 75 75 70 40 25 10 10 5 5 5 0 - -
wakame 2 tsp 0! - - - - - - - - - - - -
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