Paul Mascali
The effects of Temperature on Rapid and Chronic Tolerance of Alcohol in
Drosophila Melanogaster
Need/Knowledge Base
Alcohol is the most abused drug in the world. 30 percent of Americans have
reported having some form of alcohol use dependence. A different study showed 92% of
all seniors in the United States in the class of 1987 have consumed alcohol. 100,000
people die each year because of alcohol Men account for 80% of all these deaths. As you
can see on graph “A” alcohol has both a higher urban indigenous and urban general death
rate than any other drug such as tobacco and cocaine. On Graph “B” you can see that
more defects resulting from alcohol have arisen in the last 6 years showing the problem
growing worse as time goes on. (switch slides)
Drosophila relate to humans on a genetic level The gene that affects the
metabolism of alcohol is ADH. The alcohol dehydrogenate gene is mainly meant to
metabolize alcohol. Without it people are much more susceptible to becoming addicted to
alcohol. Different types of the fruit fly Drosophila Melanogaster have this gene as well
Although adult flies use their abilities to find ethanol to track down certain food, they are
also susceptible to intoxication and death in high ethanol environments However
Heberlein stated that fruit flies are well equipped to deal with the toxic effects of ethanol
for they use it as an energy source and as a precursor for lipid biosynthesis She was
supported by Parsons Adult flies show an increase in longevity when exposed to 0.5-
3.0% atmospheric ethanol in the absence of other food. Ulrike Heberlein has been
studying the effects of alcohol on Drosophila. She has found that Drosophila responded
to drugs a lot like most mammals do. Drosophila builds up a tolerance to alcohol and
other drugs. (change slide)
There is a scale defined by Sullivan 2000. As shown a 0 on the scale resembles
normal behavior all the way to a 7 which resembles death. Past studies used this scale and
found that a 7 on the scale would be after 20 minutes of ethanol exposure. A past study
testing the longevity of drosophila when exposed to ethanol used a 2 on the scale which is
when the drosophilae begin to become intoxicated which was after 5 minutes of ethanol
exposure. (change slide)
Natural selection also has an effect on tolerance. As many people have inferred
humans of the Asian race are more greatly affected by alcohol than other races. This
could be because of geographic isolation. With little trade and mixing of different gene
pools people of the Asian race were unable to build a tolerance. (next slide)
Literature Review, Do-ability
Tolerance means that after continued drinking, consumption of a constant amount
of alcohol produces a lesser effect or increasing amounts of alcohol are necessary to
produce the same effect. There are two different types of tolerance, rapid and chronic
tolerance. Rapid tolerance is induced by a single short exposure of huge concentrated
ethanol. Chronic tolerance is when they are exposed for long amount of time to small
concentration of the drug. Rapid and chronic tolerance appear likely to represent early
and later versions of the same set of brain adaptations to alcohol Theories about the root
causes of alcoholism often invoke the development of tolerance. Flies have a relatively
sophisticated nervous system and are capable of many well-characterized complex
behaviors, including response to drugs of abuse such as alcohol, cocaine, PCP, and
nicotine. In flies, like mammals, we have found that different types of alcohol exposure
can produce tolerance. In an experiment by Urizar made rapid tolerance by exposing
drosophila to 20 minutes to 10% but I am going to modify it to 200 proof alcohol for 10
minutes. (change slide)
A study by Pfeiler discovered that in Drosophila Pachea the male drosophila has
little ADH however females have high ADH activity. These results are suprising because
in the findings of Morozova and other scientists they found that male drosophila
Melanogaster and male humans can tolerate alcohol better than females. In Pfeiler’s
research however it is stated that after an exposure to ethanol male drosophila Pachea’s
ADH gene begins to work normally. In a study done by Peters (06) It showed that
drosophila in colder temperatures found that at low temperatures, the flies had increased
levels of lipid biosynthetic enzymes such as phospholipase D to counteract the
membrane’s increased rigidity. Possibly contributing to the insect’s ethanol tolerance.
And when the team suddenly dropped the temperatures, the insect’s ethanol tolerance
improved too. Montooth suspects that the high-latitude insect’s ability to counteract
increased membrane rigidity at low temperatures
(change slide)
null hypothesis-the drosophila that are never exposed to ethanol will have the weaker
tolerance. alternative hypothesis-based on the findings of Ulrike Heberlein flies with
chronic tolerance will have a stronger tolerance . The purpose of the study is to show that
tolerance has an affect on the metabolism of alcohol in drosophila melagastor.
This experiment will consist of three different groups of Drosophila
Melangastoer. Each group consisted of newly born drosophila before tests begin. This
insures that the flies had no prior exposures to ethanol showing no tolerance was built up.
The first group was the control group. These flies will never be exposed to ethanol until
testing. The second group built up chronic tolerance. These flies will be exposed to 5%
ethanol for 24 hours. 24 hours after the first exposure these flies will be tested. The third
and final group was rapid tolerance. These flies were exposed to 100% ethanol for 7
minutes. 5 hours after this exposure these flies were tested. All three groups were tested
in an Inebriometer. This is a 4 foot long glass tube that is filled with funnel layers and the
more intoxicated the drosophilae become the more levels they fall down. Each of these
funnel layers were placed an 18 degree angle to ensure true results. While in the
inebriometer every group will be exposed to 200 proof. The two pictures show the
exposure chamber where the Rapid and chronic groups were exposed initially and than
the other picture is showing the inebriometer.
The Group that stayed in the inebriometer the longest was the group of
drosophilae that were allowed to build up a rapid tolerance. The group that was allowed
to build up chronic tolerance stayed in the inebriometer the second longest. The
difference between the rapid group and the control was 33% which is approximately 4
and half minutes. Rapid showed a difference of 11% from the chronic group which is a
bout 2 minute longer.
Rapid tolerance is more directly related to binge drinking that goes on in most
colleges. Chronic is related closer to a steadier drinking such as a glass of wine at dinner.
These results show that binge drinking builds up a much higher tolerance. This is
important because kids who are binge drinking will build a stronger tolerance which will
lead to alcohol dependency or health problems. Results showed that when exposed to
ethanol the ADH gene in drosophila becomes more effective in breaking down ethanol.
The drosophilae that were never exposed to alcohol before the study had a much weaker
tolerance than the pre-exposed flies.
There are several limitations to this study. Because of human error the funnel
layers or baffels may not have been exactly 18 degrees off each other. Another limitation
can be shown through the genetics of the drosophila. If one group had the ADH gene and
a different group lacked that gene it would affect results.
Future studies could be to play off the addiction factor in drosophila. While
drosophilae build tolerance it is a distinct possibility that an addiction is also being built
up.
Thank you any questions?
Literature review key
Black line- 56% alcohol
Gray line-50% alcohol
White line-43%alcohol