Behavioral Responses of Aplysia californica to Three Amino Acids
Abstract
For the sea slug Aplysia californica, chemical detection allows the location of food, avoidance of predators, and ability to encounter potential mates. This is an important sensory modality because other sensory structures (optical and acoustic) are limited. It is hypothesized that food is detected via concentration gradients of specific food-derived amino acids in the water column. This study examines the behavioral reactions of Aplysia to L-alanine, L-serine, and L-methionine at a concentration of 20 mM in contrast to a food stimulus. Test subjects were placed in an aquarium and 50 mL of the amino acid was added near the source of inflow over the course of five minutes; the slug's path, displacement, and behavior were observed. Aplysia had distinct responses to each stimulus. All sea slugs (n=8) moved towards the food stimulus (a positive reaction) and displayed head turns. Head turns are indicative of the slug orienting itself to a chemical gradient. In contrast, only 40% (n=10) reacted positively to serine. For alanine, 40% (n=10) of the sea slugs also reacted positively. However, 90% exhibited head turns compared to 20% in the serine-exposed group, demonstrating that alanine was more stimulating than serine. Only 17% (n=6) of them reacted positively to methionine; all slugs displayed head turns, documenting that it was more stimulating than alanine and serine, but orientation was compromised. This suggests that Aplysia uses isolated amino acids to detect and orient to the presence of food and that serine and alanine elicit a better directed search response than methionine.
Faculty Sponsors
Dr. Joshua Feingold
Project Type
Event
Location
Alvin Sherman Library
Start Date
4-5-2023 12:00 PM
End Date
4-6-2023 4:00 PM
Behavioral Responses of Aplysia californica to Three Amino Acids
Alvin Sherman Library
For the sea slug Aplysia californica, chemical detection allows the location of food, avoidance of predators, and ability to encounter potential mates. This is an important sensory modality because other sensory structures (optical and acoustic) are limited. It is hypothesized that food is detected via concentration gradients of specific food-derived amino acids in the water column. This study examines the behavioral reactions of Aplysia to L-alanine, L-serine, and L-methionine at a concentration of 20 mM in contrast to a food stimulus. Test subjects were placed in an aquarium and 50 mL of the amino acid was added near the source of inflow over the course of five minutes; the slug's path, displacement, and behavior were observed. Aplysia had distinct responses to each stimulus. All sea slugs (n=8) moved towards the food stimulus (a positive reaction) and displayed head turns. Head turns are indicative of the slug orienting itself to a chemical gradient. In contrast, only 40% (n=10) reacted positively to serine. For alanine, 40% (n=10) of the sea slugs also reacted positively. However, 90% exhibited head turns compared to 20% in the serine-exposed group, demonstrating that alanine was more stimulating than serine. Only 17% (n=6) of them reacted positively to methionine; all slugs displayed head turns, documenting that it was more stimulating than alanine and serine, but orientation was compromised. This suggests that Aplysia uses isolated amino acids to detect and orient to the presence of food and that serine and alanine elicit a better directed search response than methionine.
