Effect of Lead on VMA1 ATPase Gene Expression and Feeding Behavior in Tetrahymena thermophila

Abstract

Lead is an environmental toxin that has been sown to have deleterious effects on human health, including neurological defects, developmental delays, and bodily pain. The purpose of this experiment was to test whether prolonged exposure to lead altered expression of the VMA1 gene and feeding behavior in the model organism, Tetrahymena thermophila. The VMA1 gene encodes the protein VMA1 (Vacuolar Membrane ATPase) which assists in regulating active transport systems on the vacuolar membrane. We hypothesized that exposure of T. thermophila to lead would result in altered expression of the VMA1 gene and in the feeding behavior of these organisms. For the experiment, control and experimental cultures of T. thermophila were maintained in a nutrient-rich media (SPP). The experimental culture media was supplemented with 0.1% lead and the cultures were maintained for 24 hours to mimic acute exposure. The feeding behavior to T. thermophila was measured using an India ink assay over the course of 24 hour treatment period. After 24 hours, RNA was extracted from the T. thermophila and Reverse Transcriptase-qualitative-Polymerase Chain Reactions (RT-qPCRs) was performed to determine expression of the VMA1 gene in control and lead-treated cultures. It was predicted that lead exposure would cause T. thermophila to starve by reducing their ability to ingest food vacuoles and that the expression of VMA1 would decrease.