Effects of ??-Methylamino-L-Alanine (BMAA) on LC4A Expression and Growth of Tetrahymena thermophila

Abstract

For this project, we wanted to explore how the presence of Beta-Methylamino-L-Alanine (BMAA) influences the growth rate of Tetrahymena thermophila and expression of the LC4A gene. BMAA is a modified L-alanine neurotoxin and non-proteinogenic amino acid synthesized by Cyanobacteria. BMAA was originally discovered in the brains of the Chamorro people who died from an Alzheimer's Disease (AD) - Amyotrophic Lateral Sclerosis (ALS) complex after ingesting bats that contained high concentrations of BMAA. A subsequent study found that the neuron death in the AD-ALS patients was due to hyperexcitation of glutamate receptors that led to an influx of calcium ions, triggering an excitotoxic cell death pathway. The LC4A gene encodes a Calmodulin protein that helps regulate calcium concentrations within a cell. We hypothesized that exposure to BMAA would cause Tetrahymena growth to decrease and expression of the LC4A gene to increase. To test our hypothesis, the media of the experimental group was treated with 1.0 mM BMAA for 7 days. The growth rate of control and BMAA-exposed Tetrahymena was measured every 24 hours during the treatment period. Immediately following the 7-day treatment, RNA extraction procedures were followed and gene-specific Reverse Transcription quantitative Polymerase Chain Reactions (RT-qPCRs) were performed on both the control and experimental groups to measure expression of LC4A. Presence of BMAA in the media was predicted to decrease Tetrahymena thermophila growth and increase LC4A expression in order to help regulate calcium ion concentrations within the cell.