Date of Award

5-13-2011

Document Type

Thesis

Degree Name

Bachelor of Arts

First Advisor

Gillen, Chris

Abstract

Aminopeptidases N (APNs) are enzymes which play a role in the digestion of proteins. APNs are found throughout the animal kingdom, and have been extensively studied in insects. We measured the mRNA expression of APNs in Manduca sexta (tobacco hornworm, order: Lepidoptera) to determine which factors affect the expression of this major player in the digestive process. Quantitative Real Time PCR was used to quantify changes mRNA expression of 4 msAPN isoforms as a function of dietary protein concentration, midgut region, and instar. We found that msAPN expression does change as a function of midgut region and instar. However dietary protein concentration did not affect the expression of msAPN. msAPN expression was 40-fold higher in the posterior midgut than in the anterior midgut. Manduca sexta larvae in the 4th instar showed a 2-fold increase in expression compared to those in the 5th instar. msAPN2 was expressed about 4-fold higher than msAPN1, msAPN3, and msAPN4. Overall, msAPN expression did not change with diet, but cohort did play a role in the relationship between expression of msAPNs and dietary protein concentration. Cohort 1 showed a 3-fold increase in expression in the larvae fed the low protein diet compared to those on the high protein diet. Cohort 2 showed 2-fold higher msAPN expression in larvae on the high protein diet than the low protein diet. Cohort 3 showed no difference between diets. In summary, we found that msAPN mRNA expression was influenced by midgut region and Manduca sexta instar; however, dietary protein concentration was not determining factor in msAPN expression.

Comments

Includes bibliographical references: pages 30-33

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