Publication Date




Embargo Period


Degree Type


Degree Name

Master of Science (MS)


Biology (Arts and Sciences)

Date of Defense


First Committee Member

Alexandra C. C. Wilson

Second Committee Member

Julia E. Dallman

Third Committee Member

J. David Van Dyken

Fourth Committee Member

Liliana M. Davalos


Sap-feeding insect have associated with bacterial symbionts for hundreds of millions years. These symbioses have increased insect fitness, facilitating their persistence through evolutionary time. The symbionts of sap-feeding insects provide their hosts with amino acids that are found at very low concentrations in their diets. Typically amino acid metabolism is partitioned between host and symbiont so that the host synthesizes non-essential amino acids while the symbiont contributes essential amino acids. The biosynthesis of some amino acids however, requires enzymes encoded by both the host and the symbiont. Understanding how amino acid metabolism is integrated between insect host and bacterial symbiont remains unclear. Functional characterization of transporters that exchange amino acids between host and symbiont can advance understanding of host/symbiont metabolic integration. In this thesis I used the pea aphid/Buchnera symbiosis model to advance understanding of host/symbiont metabolic integration. Here I report on the functional characterization of Acyrthosiphon pisum amino acid transporter ACYPI008971. Using two-electrode voltage clamp electrophysiology (TEVC) I show that ACYPI008971 responds to proline, alanine and glycine, leading me to speculate that ACYPI008971 is a transporter of these three amino acids. Based on the response of ACYPI008971 to proline, alanine and glycine I present an advanced model of host/symbiont integration of amino acid metabolism in the A. pisum/Buchnera symbiosis.


symbiosis; pea aphid; Buchnera; amino acid metabolism