Journal of Gerontology: BIOLOGICAL SCIENCES Copyright 2008 by The Gerontological Society of America
2008, Vol. 63A, No. 2, 149 150
Letter to the Editor
EFFECT OF VARYING DOSES OF CAFFEINE ON LIFE SPAN OF DROSOPHILA MELANOGASTER
Table 1. Life Span of Drosophila melanogaster Males Reared on
To the Editor:
Varying Dietary Caffeine Concentrations (0.3125 2.5 Mg/Ml) in
Despite a considerable interest in the effect caffeine has
Comparison With the Corresponding Controls
on metazoan life span, the extent, as well as the direction, of
(No Caffeine in Food)
this effect is still unclear. One of the most extensively used
Caffeine Mean Life Span Mean Life Span P,
metazoan models in longevity studies is the fruit fly
Concentration, (6 SE) (þ) (6 SE) No Kolmogorov-Smirnov
Drosophila melanogaster (1). There are a number of studies
mg/ml Caffeine Caffeine Test
on the effect of caffeine on Drosophila, most of them
2.5
conducted using natural populations. However, flies derived
Replica 1 16.9 6 0.6 46.0 6 1.4 ,.0001
from natural populations for longevity studies display
Replica 2 18.6 6 0.5 46.7 6 1.5 ,.0001
substantial variations in longevity (2), most likely brought
Replica 3 20.5 6 0.5 45.1 6 1.3 ,.0001
about by heterogeneous population-specific genetic back-
1.25
ground. In addition, the genetic instability brought about by
Replica 1 31.1 6 1.1 35.6 6 1.2 .025
an unbalanced genetic background can significantly affect
Replica 2 40.6 6 1.0 42.3 6 1.8 ,.0001
the outcome of a longevity analysis.
Replica 3 38.0 6 1.1 43.7 6 1.2 ,.0001
A good scientific experiment requires fixing of all vari-
0.625
ables except for the one under investigation. A control-
Replica 1 38.2 6 1.2 41.7 6 1.4 .013
experiment comparison analysis cannot be adequately
Replica 2 50.4 6 1.4 47.3 6 1.6 .367
achieved in longevity analyses involving natural popu-
Replica 3 43.1 6 1.3 42.6 6 1.5 .281
lations due to their inherent genetic variability and, thus,
0.3125
varying genetic background of organisms involved in
Replica 1 42.2 6 1.4 43.5 6 1.3 .588
the study.
Replica 2 50.0 6 1.6 48.4 6 1.7 .715
In the present study, we used a co-isogenic inbred line
Replica 3 41.4 6 1.2 44.5 6 1.3 .001
of D. melanogaster derived from the Canton-S (CS) stock
Notes: SEźStandard error of mean.
to assess the effect of varying dietary doses of caffeine on
Each concentration was tested in three separate replicas, which are presented
life span in an equalized genetic background. Being a labo-
in the table individually.
ratory strain of D. melanogaster, CS has reduced genetic
variation within the strain (1). Another feature of CS is
particularly D. prosultans, contain large numbers of TEs in
that it is reported by the Drosophila Stock Center to have
their genome (1,6,7,8,9).
no potentially transpositionally active transposable elements
Transposable elements are major contributors to genetic
(TEs), such as P or hobo, in its genome (3). Transposable
instability in Drosophila, which contributes greatly to
elements can introduce additional genetic heterogeneity and,
variations in life span (4). Somatic movement of TEs found
thus, additional instability in response to environmental
in the D. prosultans genome has been documented to reduce
stress (4). Previous studies with fruit fly longevity did not
life span in other species of Drosophila (10,11). Transposable
take the TE factor into account.
element activity could have modified the effect of caffeine on
In our experiment, we observed a significant reduction in
life span in the Itoyama and colleagues study (5).
life span of male flies reared on food containing 2.5 mg/ml
Data presented here show that high concentrations of
and 1.25 mg/ml of caffeine (Table 1, Figure 1). There was
caffeine reduce the longevity of an inbred strain D. melano-
a significant decrease in life span in the experimental group
gaster with a co-isogenic background lacking TEs. Whether
in one out of three replicas with 0.625 mg/ml and 0.3125
mg/ml caffeine concentrations. In two out of three replicas
with 0.625 mg/ml and one out of three replicas with 0.3125
mg/ml of caffeine, flies lived longer on caffeine than on
control food, although the difference in life span was not
significant. The overall relationship between caffeine con-
centration and Drosophila life span in our experiment is
presented in Figure 1.
A previous report on caffeine effect in Drosophila
examined the development of resistance to caffeine in 10
generations of Drosophila prosultans, a tropical fruit fly (5).
The results of that investigation suggest a negative dosage-
dependent effect of caffeine on longevity and other life
history parameters. However, the lack of experimental
replicas makes the results of that study difficult to put into
Figure 1. Mean life span of Canton-S Drosophila melanogaster males of four
perspective. In addition, natural populations of Drosophila, dietary concentrations of caffeine with corresponding controls.
149
150 LETTER TO THE EDITOR
2. Curtsinger JW, Fukui H.H, Khazaeli AA, et al. Genetic variation and
the observed relationship between caffeine and life span will
aging. Ann Rev of Gen. 1995;29:553 575.
hold in other genetic backgrounds, whether or not they
3. http://flystocks.bio.indiana.edu
contain TEs capable of transposition, remains the subject of
4. Nikitin AG, Shmookler Reis RJ. Role of transposable elements in age-
further investigation.
related genomic instability. Gen Res. 1997;69:183 195.
5. Itoyama MM, de Campos Bicudo HEM, Manzato AJ. The development
of resistance to caffeine in Drosophila prosaltans: productivity and
Alexey G. Nikitin1
longevity after ten generations of treatment. Cytobios. 1998;96:81 93.
Serena Navitskas2
6. Finnegan DJ. Eukaryotic transposable elements and genome evolution.
Lee-Ann Nicole Gordon2
Trends Genet. 1989;5:103 107.
1
Biology Department
7. Castro JP, Carareto CMA. Canonical P elements are transcriptionally
2
active in the saltans group of Drosophila. J Mol Biol Evol. 2004;59:
Biomedical and Health Sciences Department
31 40.
Grand Valley State University
8. Koslovski Sassi A, Herédia F, Loreto ELS, et al. Transposable elements
Allendale, Michigan
P and gypsy in natural populations of Drosophila willistoni. Genet Mol
Biol. 2005;28:734 739.
9. Castro JP, Setta N, Carareto CMA. Distribution and insertion numbers
Address correspondence to Alexey G. Nitikin, Biology Department,
of transposable elements in species of the Drosophila saltans group.
Grand Valley State University, 1 Campus Dr., Allendale, MI 49401.
Genet Mol Biol. 2006;29:384 390.
E-mail: [e-mail]
10. Woodruff RC. Transposable DNA elements and life history traits. I.
Transposition of P DNA elements in somatic cells reduces the lifespan
of Drosophila melanogaster. Genetica. 1992;86:143 154.
REFERENCES
11. Woodruff RC, Nikitin AG. P DNA element movement in somatic cells
1. Ashburner M. Drosophila: A Laboratory Handbook. Cold Spring reduces lifespan in Drosophila melanogaster: evidence in support of
Harbor, NY: Cold Spring Harbor Laboratory; 1989. the somatic mutation theory of aging. Mutation Res. 1995;338:35 42.