Meeting Abstract

P2.92  Sunday, Jan. 5 15:30  A volumetric analysis of the tracheal system of the grasshopper Schistocerca americana using µCT SIEVE, J*; AVILES, J; HARRISON, JF; SOCHA, JJ; Virginia Tech; Virginia Tech; Arizona State University; Virginia Tech sjake5@vt.edu

Although insects possess an open coelom, recent work suggests that grasshoppers are able to create functional compartments within the body. These compartments appear to reduce the movement of hemolymph, which baths all tissues and organs including the respiratory tracheal tubes and air sacs. Anaesthetized grasshoppers exhibit less control of hemolymph distribution: when the animal is experimentally held in a vertical position, air sacs at the bottom end collapse regardless of orientation (head up or head down). In this study, our aim is to characterize the three-dimensional geometry of the tracheal system to determine the volumetric effects of body orientation on hemolymph distribution and tracheal configuration. We used micro-computed tomography (µCT) to visualize the exoskeleton and tracheal system of the grasshopper in two orientations: head up and head down. In addition, we included a treatment with the spiracles sealed to begin investigation of the role of intra-tracheal pressures in tracheal system compression. Sacrificed grasshoppers were scanned using a SkyScan 1172 high-resolution µCT scanner using x-ray energy, amperage, and power settings of 70kV, 140µA, and 10W, respectively. Our preliminary results demonstrate that tracheal tubes with diameters as small as 10 micrometers are able to be visualized, providing the first three-dimensional representation of the major structures of the tracheal system in a grasshopper. Quantification of tracheal volumes using Amira software will enable us to determine the specific effects of orientation on the respiratory capacity. Supported by NSF 0938047.