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2000 Symposium Abstracts
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Elasticity of the Bovine Aorta. LISA SOPER. Notre Dame
Academy, 1699 Hilton Drive, Covington, KY, 41011-2796.
A cow heart was obtained from a local meat
market. The aorta was cut from the heart and sliced into rings one
cm wide. The artery segments were stretched between metal rings on
each end, with the top ring attached to a metal bar, and the bottom ring
to a force probe. The computer interfaced probe was used to record
the force as the artery was stretched and then gradually released. NIH
Image was used to capture and analyze two images for each force: a
far picture, showing the entire arterial ring, and a close-up. From
these data, stresses and strains were calculated. The rings demonstrated
elastic behavior when stretched and released. This elasticity was
greatly reduced when the rings were tested after being boiled in water.
Effects of magnetic fields on maturation of Tenebrio molitor.
MOLLIE WOLKING. Notre Dame Academy, 1699 Hilton Drive, Covington, KY 41011-2796.
The effect of magnetic fields on living organisms
is still a widely studied topic. On the day of their emergence as
pupae, Tenebrio molitor were placed in magnetic fields with strengths
of 0.33mT or 290 mT. The pupae that were placed in the 0.33 mT field
were also placed in an air-conditioned room at 19oC, and the pupae in the
290 mT field were at room temperature or in a 3oC refrigerator.
Pigmentation development during the first seven days of the adult stage
was studied by capturing images daily and using NIH Image software.
There was no statistically significant difference in the beetles' pigmentation
formation in the magnetic fields and in the control, whether at room temperature
or at 19oC. The time for the pupae to emerge into adults was
also studied. The average time for the pupae in the control to emerge
was 16.5 days, and for the pupae in the 0.33 mT magnetic field the average
was 17.3 days. There was a statistically significant difference in
these values. Metamorphosis was so slowed at 3oC that
adults have not emerged from the pupal stage after 40 days. Studies
of respiration rates of the pupae were attempted but equipment sensitive
enough to record such data was not available.
Bacillus thuringiensis and Bacillus sphaericus as Insecticides
Against Culex pipiens. GREGORY WETZEL, duPont Manual High School,
120 W. Lee St., Louisville, KY 40208.
The spread of diseases through the mosquito
vector is a problem in third world countries and persons who travel to
these places. The fact is that most of the insecticides or repellants
are either harmful to the environment or not very effective. That
is why there is a growing interest in formulating natural ways to repel
or curb the mosquito population. This project tests the effects of two
bacteria, Bacillus thuringiensis var. israelensis and Bacillus
sphaericus, as natural insecticides against mosquito larvae of the
species Culex pipiens. There were two control groups, one
containing the alga Spirogyra, the other void of any microbials.
The first control group was utilized because if there was a difference
between the mortality rate in the experimental and control groups, it would
be due to the bacterium itself, not the presence of a foreign microbial.
Each of the four groups consisted of ten tubes, each with three larvae
in it. One ml of broth, 1 ml of Alga-Gro, and 5 ml of distilled water
was added to each tube. The groups were incubated for 120 hr at 30oC,
and the number of dead larvae in each tube was recorded at 24 hr and 120
hr. The results were analyzed using an analysis of variance (ANOVA)
to determine significance. The ANOVA showed the results to be significant
after 24 hr, with a .0000000165 probability that the results were random
while the results after 120 hrs were shown to have a .57 probability that
they were purely random, and thus not significant.
The Effect of an Antioxidant Diet on the Life Span of Drosophila
melanogaster. BEN WATKINS, duPont Manual High School, 120 West
Lee Street, Louisville, Kentucky, 40208.
Antioxidants are believed to slow the aging
process and extend life span by attacking free radicals, by-products of
normal metabolism that cause oxidative damage. Research by Professor
William Orr of Southern Methodist University showed that genetically altering
fruit flies (Drosophila melanogaster) to increase antioxidant production
almost doubled average life span. This experiment was designed to
test the theory that a diet rich in antioxidants could produce similar
results.
The fruit flies were divided into three groups
and fed three different diets throughout their different life stages.
The control group was fed a basic mixture of potatoes and sugar with yeast
sprinkled on top. The orange antioxidant group was fed the same basic
mixture with an orange added. Oranges contain high levels of vitamin
C, a known antioxidant. The tomato antioxidant group was fed the
basic mixture with a tomato added. Tomatoes contain high levels of
vitamin C and lycopene, and so contain two known antioxidants. Once
adult flies emerged, their life spans were measured by recording the adult
deaths daily.
The results partially supported the hypothesis.
The mean adult life span of the tomato group was highest (9.52 days), while
the orange group showed a slightly lower mean adult life span (7.92 days)
than the control group (8.62 days). The increased life span of the
tomato group was mostly attributed to 11 of the 50 adult flies in the group.
Some of these 11 flies lived almost twice as long as any individual in
the orange and control groups.
Daphnia magna: An Alternative Model for in vivo Assessment
of Cardiac Toxicity. STEPHANIE N. GRANT, du Pont Manual Magnet High
School, 120 West Lee Street, Louisville, KY 40208.
In humans, cardiac glycosides exhibit cardiotonic
effects, however, some are used therapeutically. Daphnia magna
are small invertebrate animals that live in freshwater environments.
The heart of a D. magna is a small, muscular sac located dorsally
behind the large eye. The purpose of this experiment was to determine
if D. magna exhibit the same pharmacological effects as humans.
If they do, then they could possibly be used as an alternative model for
in vivo assessment of cardiac toxicity. It is hypothesized that the
D.
magna will react to cardiac glycosides the same as humans.
In order to determine if D. magna exhibit
the same effects as humans when exposed to cardiac glycosides, the D.
magna were treated with different concentrations of the cardiac glycosides
digoxin, oleandrin, and uzarin. Digoxin and oleandrin decrease the
heart rate of humans. However, due to structural differences, uzarin
does not. A total of ten trials were conducted. Each trial
consisted of treating ten D. magna with each of the concentrations
of the cardiac glycosides.
The heart rates of the D. magna exhibited
the same pharmacological effects as humans when treated with the respected
cardiac glycoside. The Wilcoxon Signed Rank Test proved that the
data was significant. The research hypothesis was fully supported.
It was concluded that D. magna exhibit the same response as humans
to the cardiac glycosides digoxin, oleandrin, and uzarin.
The Effect of Saline on the Length of Nymphs of the Suborder Anisoptera.
ZOE ZHANG, duPont Manual High School, 120 West Lee Street, Louisville,
KY 40208.
As the population of many insects increase,
an alternative form of insect control can be found in dragonflies (insects
of the suborder Anisoptera). A dragonfly can eat an insect
every three minutes, but to reach this adult form, they must spend years
in the nymph stage. If the time spent in this period can be shortened,
the population of dragonflies will increase, maintaining the balance of
nature.
In order to molt, dragonflies need copious
amounts of proteins and mineral. A common mineral is sodium chloride
or table salt. The hypothesis is that up to a certain threshold,
the length of dragonflies will increase as the concentration of sodium
chloride increases. Beyond this threshold, either the ATP of a cell
will be utilized for stabilizing the intracellular environment rather than
molting, or the cells will crenate.
Thirty-six dragonfly nymphs were placed in
jars containing saline concentrations of 0.05, 0.1, and 0.15%. In
comparison to the control spring water, the changes in the lengths of the
nymphs show no statistically significant growth with the increase of saline
concentration.
Therefore, the research hypothesis is rejected
and the null hypothesis that saline concentration does not have an effect
on the molting rate of dragonfly nymphs must be taken into account.
Because sodium chloride failed to increase the molting rate of dragonfly
nymphs, it may be hypothesized that either this particular mineral, or
an abundance of minerals overall, does not trigger the release of the molt
regulating hormone Ecdysone.
- [Abstract
Index]