Open Collections

Ames, Tahnee

University of British Columbia

Aquatic larvae of the genus Chaoborus (Diptera: Chaoboridae) are the only truly pelagic insects in the world because they can precisely regulate their buoyancy. By controlling the volumes of two internal pairs of air-filled sacs Chaoborus larvae are able to float, sink or remain neutrally buoyant in the water column, and they can also compensate for the changes in air-sac volume that result from changes in hydrostatic pressure with depth. Varying the air-sac volume changes the overall density of the larvae: more volume of air allows the larvae to ascend, and less allows them to descend. This is due to the unique mechanochemical mechanism of the air-sac wall, comprised of alternating transverse bands of cuticle and resilin and surrounded by a thin epithelial layer. Resilin is an elastic protein which responds to changes in pH, expanding when in an alkaline environment and contracting in an acidic environment. Exactly how the pH of the air-sac wall was controlled was previously unknown. Using an RNAseq approach, I uncovered a suite of pathways found in the air-sac that are potentially involved in pH regulation. I propose a model in which apical VHA secretes H⁺ into the lumen, generating an electrical potential that drives the efflux of Cl⁻ via pHCl-2 to reduce the transmembrane potential and acidify the air-sac’s resilin bands. To alkalinize the resilin, I propose a model in which an apical NHA1 likely acts as either a symporter or exchanger, moving Cl⁻ and H⁺ back into the epithelium or exchanging Cl⁻ for OH⁻. These proposed models arise from a transcriptomic exploration into a previously unknown regulatory mechanism, uncovering potential pathways that can be verified in future studies. By comparing these expression pattern of Chaoborus air-sacs to the basal tracheae of the closely related Eucorethra underwoodi, I uncovered the potential evolutionary trajectory of the air-sac.

Text

2024-04-22

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87920

Zoology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/