Meeting Abstract

P1.224  Wednesday, Jan. 4  The use of SR-µCT for 3D visualization of insect tracheal systems MILLER, L.*; WATERS, J.S.; HARRISON, J.F.; VANDENBROOKS, J.M.; YAGER, D.D.; XIAO, X.; DE CARLO, F.; SOCHA, J.J.; Virginia Tech; Arizona State U.; Arizona State U.; Arizona State U.; U. Maryland; Argonne National Lab.; Argonne National Lab.; Virginia Tech jjsocha@vt.edu

The morphology of the insect respiratory system consists of an immense network of tracheal tubes and airsacs that range in size from the millimeter to sub-micron scale and permeate the entire body. Gases are exchanged directly from tracheae to the tissues largely without a circulatory component. Because patterns of diffusive or convective air transport depend on network geometry, the structural design of the system is critical to understanding its performance. Despite its importance, the three-dimensional morphology of insect tracheal systems has not been well characterized, largely due to the difficulty of obtaining reliable or accurate data. Here we demonstrate the use of synchrotron radiation microcomputed tomography (SR-µCT) to visualize the three-dimensional tracheal systems of intact insects. Samples were prepared fresh (with no tissue fixation) by sacrificing the insect with ethyl acetate and then securely mounting the sample in x-ray transparent polyimide tubes. In a scan, approximately 1400 projection images are recorded while the sample rotates 180° about the vertical axis, a process that takes on the scale of seconds using a high-speed camera. The 3D morphology of tracheae and airsacs in multiple species was successfully imaged, including samples from ant, beetle, fruit fly, preying mantis, and butterfly taxa. We compare image results to those from other techniques such as confocal microscopy and stereological point-counting. The resolution of confocal microscopy was slightly greater, enabling the visualization of more sub-micron tracheoles in fruit fly muscle tissue, but SR-µCT allowed larger sample volumes to be imaged. We conclude that SR-µCT is a highly effective technique for obtaining three-dimensional tracheal system morphology.