First published online September 19, 2006
Journal of Experimental Biology 209, 3837-3850 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02448
Membrane lipid physiology and toxin catabolism underlie ethanol and acetic acid tolerance in Drosophila melanogaster
Kristi L. Montooth1,*,
Kyle T. Siebenthall2 and
Andrew G. Clark2
1 Department of Ecology and Evolutionary Biology, Brown University,
Providence, RI 02912, USA
2 Department of Molecular Biology and Genetics, Cornell University, Ithaca,
NY 14853, USA

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Fig. 1. Systems of genes/enzymes underlying ethanol metabolism and lipid-derived
signaling pathways, along with the regulatory effects of the sterol regulatory
element binding protein (dSREBP). The two parallel curved lines represent the
plasma membrane. AcCoAS, acetyl-CoA synthetase; ADH, alcohol dehydrogenase;
ALDH, acetaldehyde dehydrogenase; DAG, diacylglycerol; PC,
phosphatidylcholine; PE, phosphatidylethanolamine; PEth, phosphatidylethanol;
PLD, phospholipase D; PPAP, phosphatidate phosphatase.
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Fig. 2. Correlation between ethanol and acetic acid tolerances across species of
Drosophila and populations of D. melanogaster. Points
represent the lethal dose of toxin causing a 50% male mortality
(LD50) in each genetic line. Error bars represent 95% confidence
intervals for LD50 values. Australian population data are from
flies acclimated to and tested at 15°C. All others are from a survey of
tolerances in flies reared and assayed at 24°C.
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Fig. 3. ADH activities and ethanol tolerances for each Adh genotypic
class. Lines are categorized as having only the Adh-F allele (F,
N=5 lines), only the Adh-S allele (S, N=5 lines) or
having both alleles (F&S, N=10 lines). Data are least square
means ± 1 standard error. The inset contains Adh expression
data (1/Ct) for the three genotype classes.
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Fig. 4. Mortality curves for extreme high and low ethanol tolerant lines acclimated
to and assayed at 26°C. Symbols represent the two replicate observations
for each line at each of five ethanol concentrations. Lines with 95%
confidence intervals (horizontal bars) are fits from probit regressions from
which we obtained estimates of LD50.
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Fig. 5. Population and temperature acclimation effects on ethanol tolerance (A),
the ethanol catabolic enzymes, ADH (B), AcCoAS (C) and two putative
AcCoAS-encoding loci (D). Shown are least square means ± 1 standard
error and significant fixed effects from mixed-model ANOVAs. Fold expression
changes were calculated from serial dilution standard curves.
*P<0.05, **P<0.01,
***P<0.001, ****P<0.0001.
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Fig. 6. Phosphatidylethanolamine (PE) biosynthesis pathway (A) and the population
and temperature acclimation effects on expression of genes encoding enzymes in
this pathway, as well as a fatty acid desaturase (B). Shown are least square
means ± 1 standard error and significant fixed effects from mixed-model
ANOVAs. Units of expression are (1/Ct)x1000. Fold expression changes
were calculated from serial dilution standard curves. CDPET, CDP-ethanolamine
diglyceride transferase; PECT, phosphoethanolamine cytidylyltransferase; SPLY,
sphinganine-1-phosphate lyase. *P<0.05,
**P<0.01, ****P<0.0001.
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Fig. 7. Population and temperature acclimation effects on activity (A) and
expression (B) of the lipid-mediated signaling enzyme, phospholipase D (PLD).
Shown are least square means ± 1 standard error and significant fixed
effects from mixed-model ANOVAs. Fold expression changes were calculated from
serial dilution standard curves. *P<0.05,
****P<0.0001.
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Fig. 8. The effect of rapid thermal shifts on ethanol tolerance. Flies reared at
26°C and shifted to 15°C (left) had increased ethanol tolerance,
whereas flies reared at 15°C and shifted to 26°C (right) had decreased
tolerance. Data are least square means ± 1 standard error.
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Fig. 9. The effects of a rapid thermal shift from 26°C to 15°C, which
should increase membrane rigidity, on the expression of genes involved in
phosphatidylethanolamine (PE) biosynthesis (A; Sply, Cdpet), membrane
lipid signaling (B; Pld, Wun) and encoding a putative AcCoAS (C;
CG6432). Shown are least square means ± 1 standard error and
significant fixed effects of
TExpose(TRear) from mixed-model
ANOVAs. Units of expression are (1/Ct)x1000. Fold expression changes
were calculated from serial dilution standard curves.
**P<0.01, ***P<0.001,
****P<0.0001.
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Fig. 10. The response of acetic acid tolerance (A) and dSrebp expression
(B) to temperature acclimation. Shown are least square means ± 1
standard error and significant fixed effects. *P<0.05,
****P<0.0001.
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© The Company of Biologists Ltd 2006