Here is the report... this is the rough draft I don't have the final copy one of my partners does. sorry
Mutagenic effects of Aspartame on Drosophila
Abstract
Aspartame is in over 4,000 products worldwide, and is consumed by over 200 million people in the United States alone. Aspartame is also suspected to cause cancer and neurological problems. Our group tested if aspartame had any mutagenic effects on Drosophila. Aspartame was given to male Drosophila and then they were bred with the attached X females. Do to the nature of the attached X females, introduction of a Mutagen to the sperm would reduce the number of male offspring produce through breeding with these females. After the eggs were laid and matured, the sex ratio of the progeny was observed. We detected a positive correlation between aspartame and the reduction of male to female ratio. The results showed aspartame to be a mutagen.
Introduction
Aspartame was discovered in 1965 at G.D. Searle & Company by a researcher named Mr. James Schlatter. It was originally created for the treatment of ulcers, which proved unproductive. Aspartame was found to be approximately 180 times sweeter than sucrose, or table top sugar, making it a perfect artificial sweetener. In 1974 the FDA approved aspartame as a food additive. Then in 1976 an FDA “task force” reported possible fraudulent testing of the safety of aspartame. These results were largely ignored due to pressure from G.D Searle & Company. Aspartame naturally decays into methanol, phenylketonuria, and most importantly formaldehyde, which is a known mutagen (Gold 1998). Corporations such as Monsanto, owner of NutraSweet, claim that in vitro aspartame was digested before it could decay into its toxic products. Mutagen experiments on Drosophila showed inconclusive results from aspartame exposure (Evans 1998).
Our hypothesis is that aspartame will affect the ratio of male to female Drosophila, thus proving that it is a mutagen. To test this, a special breed of Drosophila was collected. This breed had females with attached-X syndrome. This condition results from having 2 X-chromosomes attached together as one. When these females breed, only the offspring carrying the attached X-chromosome will be female. Male offspring will have to have inherited the X-chromosomes from their father only. So if a mutagen is given to the males, and their X-chromosome is damaged in spermatogenesis, there will be a lower ratio of males to females.
Mutagen tests using Drosophila work by detecting the rate of mutation of a lethal gene needed for male Drosophila development. The Y-chromosome in Drosophila is irrelevant, therefore sex is determined by the number of X-chromosomes. Male Drosophila only have one X-chromosome, and their female counterparts have two. This produces a hypo-proportionate rate of gene expression in male Drosophila. This problem is countered by genes that double the expression rate in male Drosophila’s X-chromosome. In Drosophila, X-chromosome expression compensation is regulated by Male Specific Lethal (MSL) genes (Sofer 1998). As the name implies, if the genes are not functional, male offspring will die off in the early larva stages. If a mutagen is given to Drosophila, the MSL genes can be damaged, and the ratio of male to female offspring will be altered in favor of females. This is a common means of determining if a substance is a mutinagen.
Method and Materials
This experiment was performed at St. Cloud State University from Oct. 7th, 2002 to Nov. 20th, 2002. In the experiment, three vials with five to six males and five to six attached X females were bred together. Drosophila were then sexed in the late pupae stage to reduce the chance of collecting impregnated females. Two vials of the male species were then collected. One of the vials was given normal nutrients, while the other was given nutrients, plus .05g/ml of aspartame. The nutrients contained powder type flakes which were food for the flies to feed off of. The appropriate amount of aspartame was based on the recommended maximum daily dosage (for humans) from Nutrasweet.com (Nutrasweet 2000). The aspartame was collected from Equalâ sugar packets. The aspartame was only at 5% purity, while the other 95% was dextrose, a sugar made from corn. Once this solution was made, a cotton ball was placed in it to soak up the fluid. This was then placed in the male test vial. After 24 hours of exposure, the 6 exposed males were placed with 6 virgin females in a vial containing nutrients. The same was done with the controlled, only differences being these males were not exposed to aspartame. After 10 days, the parents were removed from the vials. For the removal of flies, fly nap was placed on a cotton swab and put in the vial until the flies fell asleep. This makes sure that no flies escape while removing them. At 14 days after breeding, the progeny were sexed and counted once a day for four days. The experiment was complete after the progeny were counted and totaled.
Results
Fig. 1 Fig. 2
Fig. 3
Fig. 4
Figures 1 and 2 show the percentage of males to females from the total number of flies collected in each group. In total, 36 flies were counted from the controlled, and 80 were counted in the experiment. Figure 3 and 4 show the raw data collected in 5 days. There was actually no data collected on 11/16/2002, instead the final count was done on 11/20/2002.
Discussion
As stated in the hypothesis, we felt that aspartame would have an affect on the male to female ratio. The hypothesis turned out to be correct. A final ratio of ~2.6 males to every 1 female was collected from the control, and a ratio of ~1.2 males to every 1 female was collected from the experiment group. The Chi2 results were 17.55 which is above the standard significance level of 5%, or Chia = .05 = 9.48. There was less then a 5% chance of getting these results by random. This means that these results are statistically significant proving that aspartame did in fact change the sex ratio in the experiment. This does not mean the results are full proof, as seen in Figures 4 & 5, there are variations over each day. This variation could have been reduced if a larger number of flies would have been used in the start of the experiment.
In all, the results show that aspartame produces a mutagen like drop in male offspring. When compared with other mutagen experiments, the results further prove aspartame is a mutagen, and is unfit for human consumption.
References
1. Evans, Dr. David. 1998 Nov. 2. 94-200 Introductory Toxicology “Genetic Toxicology”.
http://uoguelph.ca/mbgwww/courses/94200/toxicology7.html. Accessed 2002 Nov. 14.
2. Gold, Mark. 1998 June. 26. Aspartame (NutraSweet) Toxicity Info Center.
http://www.holisticmed.com/aspartame/. Accessed 2002 Nov. 14.
3. Sofer, William. 1998 Oct. 26. Sex Linked Genes and Sex Determination.
http://waksman.rutgers.edu/~sofer/genetics/week9/lecture11-2.html. Accessed 2002 Nov. 14.
4. Nutrasweet. 2000. ADI (Acceptable Daily Intake).
http://www.nutrasweet.com/infocenter/index.asp. Accessed 2002 Oct. 19
