A teaching laboratory on the activation of xenobiotic transporters at fertilization of sea urchins.

Abstract

Sea urchin gametes have been historically used to demonstrate fertilization and early development in student laboratories. Large amounts of egg and sperm are easily acquired, and the conspicuous changes in egg surface morphology, indicative of sperm-egg fusion and egg activation, are readily observed in the classroom. However, less often incorporated into teaching labs are exercises that demonstrate the dramatic metabolic changes that accompany egg activation. One example is the massive up-regulation of various essential transport activities in the embryo's plasma membrane, including xenobiotic transporter activity. Here we outline a laboratory that incorporates this concept into a teaching lab, capitalizing on the magnitude and uniformity of the xenobiotic transporter activation event in certain species of sea urchins. The introduction of this chapter provides background information for the instructor, and the remainder serves as a laboratory manual for students. The experiments detailed within the manual can be completed in a total of 4-8h spread over one or two lab periods. The lab manual guides students through a modified version of the United States Environmental Protection Agency (EPA) toxicity test, a novel undergraduate-level laboratory on xenobiotic transporters, and analysis of microscope data using ImageJ. We have found this lab to be of interest to a wide range of biology and environmental science undergraduates, and effective in teaching underlying concepts in developmental biology, physiology and toxicology.