Meeting Abstract

P2.199  Thursday, Jan. 5  How Flies Stumble: The Effects of a Glutamate Agonist on Climbing Ability in Adult Fruit Flies HUSAIN, DI*; GONZALEZ, G; MAXKWEE, K; BERG, O; GOTO, JJ; MULLER, UK; California State University, Fresno; California State University, Fresno; Fresno City College; California State University, Fresno; California State University, Fresno; California State University, Fresno umuller@csufresno.edu

Previous studies have shown that the neurotoxin BMAA, a glutamate agonist, affects the walking behavior of fruit flies: high doses cause loss of motor ability (flies are unable to walk up an incline and right themselves after a fall); low doses cause hyperactivity (fruit flies walk faster and longer). Flies treated with low doses also stumble more often: they are more likely to lose their footing and roll down the incline. In this study we explored whether treated flies lose their footing more often because they walk faster or because BMAA affects their motor control. Our Null hypothesis is that walking faster reduces the contact surface and duration of the stance phase, making the flies more likely to lose their footing during incline walking. If loss of motor control is caused by BMAA, then the geometries of the tripod gait would be significantly altered, showing loss of fine motor control. Adult fruit flies were fed BMAA at four doses (0, 12.5, 25 and 50 mM BMAA); their walking behavior was recorded for 30 minutes 24 hours after feeding started. We digitized the footfall pattern of flies to determine the effect of BMAA on the tripod gait, walking speed and number of stumbles. We found that in the control flies, stumble frequency does not increase monotonically with walking speed, but the highest stumble frequency occurs at 2 mm/s with two thirds of the stumbles at velocities of 4 mm/s and below. In treated flies, stumble frequency peaks between 3 and 6 mm/s. Our data on footfall pattern suggest that BMAA impairs motor ability, leading to an increase in stumble frequency due to impaired leg coordination.