Introduction In 1998, the Calorie Control Council estimated that 144 million American adults...
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Transcript of Introduction In 1998, the Calorie Control Council estimated that 144 million American adults...
Introduction
In 1998, the Calorie Control Council estimated that 144 million American adults regularly consume low-calorie, sugar-free products.
To date the U.S. Food and Drug Administration have approved five sugar substitutes, one of them being aspartame.
Purpose The purpose of this study, is to determine the effects of
aspartame consumption on fat deposition in C. elegans as a potential indication of aspartame activation of the cephalic
response.
Hypotheses Hypothesis #1: The starved (lean) C. elegans will demonstrate no difference in fat
deposition between groups.
Hypothesis #2: Supplementation of aspartame will lead to an increase in fat deposition due to a cephalic response.
Cephalic Phase Response
Giduck (1987) found that oropharyngeal - stimulated responses are reliably initiated by the taste and smell of food.
Nicolaidis (2003) suggests that cephalic responses play an important role in the regulation of both digestive and metabolic processes and act to optimize the utilization of the ingested nutrients.
Salivary SecretionsSalivary Secretions The sight, smell, thought or taste
of food initiates the cephalic response through salivating.
Blood sugar levels decrease.
The sight, smell, thought or taste of food initiates the cephalic response
through salivating. Blood sugar levels decrease.
Gastric SecretionsGastric Secretions Dive – like mechanism is stimulated in
the brain which creates a greater desire for food.
Originates from the cerebral cortex and appetite centers of the brain which
are mediated by the vagus nerve.
Dive – like mechanism is stimulated in the brain which creates a greater desire
for food. Originates from the cerebral cortex
and appetite centers of the brain which are mediated by the vagus nerve.
Literature Review
Ashrafi (2007) and Rankin (2005) found that due to the chemo sensitivity and cephalic response system in C. elegans, they are an ideal organism for the study of
energy balance (fat deposition).
Methodology
Sudan Black Staining & Nomarski Optics Used for the identification of fat deposits in C.elegans intestines
Glucose Supplemented N2 Aspartame Supplemented N2Control Starved N2
N2 Strain Caenorhabditis elegans (n=30)
Pilot Studies Conducted prior to experimentation in order to determine the
needed concentrations of glucose and aspartame for the axenic liquid medium (10%).
Statistical Analysis - ANOVA (Sheffe Post Hoc) (p<.05)
Mean + SD
Fat Deposition Measurements (Photoshop)
Relative Luminosity Evaluation
This bar graph demonstrates the dark pixel mean (from the Adobe Photoshop Histogram Function) of the control group (68.44 + 1.74), glucose supplemented group (69.18 + 1.29)
and the aspartame supplemented group (62.77 + 1.59).
Images of the stained C. elegans were evaluated for relative luminosity. Regions of black pixels in the image (representing areas of fat deposition) were compared to the lighter areas
of negligible fat deposition. The dark pixel mean of the image was reported and used for statistical analysis of the overall fat deposition.
Control Starved C. elegans(Mean = 62.89 dark pixels)
Glucose Supplemented C. elegans(Mean = 71.56 dark pixels)
Aspartame Supplemented C. Elegans(Mean = 60.22 dark pixels)
Discussion I An early limitation of the study included a non-
sterile laboratory environment. Contamination of C. elegans cultures created a food source from
which the worms would feed, essentially prolonging their lifespan.
Additionally, there was an inability to precisely record the absorption of the glucose and the
aspartame by the C. elegans.
Discussion II The mean fat deposition of each group reflects the starved worms compensating for negligible
calories by storing more fat.
The glucose supplemented worms deposited fat by consuming excess calories from
the glucose.
The aspartame supplemented worms deposited the least amount of fat since aspartame is not a
source of energy which the C. elegans could feed off of.
The one-way ANOVA followed by a Sheffe Post Hoc (p<.05) revealed a significant difference
between the control and glucose supplemented groups and the glucose and aspartame
supplemented groups. No significant differences were found between the control and glucose
supplemented groups.
Conclusion This study rejects hypothesis #1 due to
differences in fat deposition found between the C. elegans groups as previously
mentioned.
This study also rejects hypothesis #2 since supplementation of aspartame does not lead to increased fat deposition. It is believed that this may be due to a lack of available energy
sources in the aspartame group.
Future Studies Possible future studies could include…
Incorporating the no-calorie sweetener Sucralose (Splenda) into future trials and observing subsequent fat deposition.Training C. elegans in an aspartame feeding environment and transferring them into a glucose
feeding environment to measure fat deposition.
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