Understanding insect respiration using bio-inspired microfluidics
The Casas lab seeks a qualified student to carry out a Masters 2 project at the interface between organismal insect biology, systems physiology, microfluidics and bioinspiration.
Context: Larvae of Lepidoptera (caterpillars) are among the most rapidly growing animals in the world. A few weeks after hatching, they attain masses several thousand-fold higher than their initial masses. To support rapid growth, they rely on high-performance systems for feeding, digestion, and gas exchange. Midgut tissues and contents can make up 40% of larval mass, with gut transit times of just a few hours, during which time larvae can raise midgut pH to > 10 – 11. These extreme conditions are supported by high rates of oxygen consumption and carbon dioxide emission. This project examines the coupling of midgut physiology and respiratory gas exchange. Specifically, we hypothesize that the midgut acts as a sink for carbon dioxide. In aqueous solutions, CO2 gas is in equilibrium with carbonic acid, bicarbonate, and carbonate. Because alkaline solutions, like midgut fluids, strip protons from carbonic acid, they push the chemical equilibria toward bicarbonate and carbonate. The midgut thus causes both oxygen and carbon dioxide to disappear from the tracheal system, which should cause net convective flows of tracheal gases toward the gut. Woods and Casas have already developed mathematical models of these processes, and now we would like to develop physical models for testing aspects of the modeled gas dynamics.
Specific aim: We seek a student to develop physical models capable of testing several ideas about the coupling between gut physiology and respiratory gas exchange. In particular, we want to measure how readily CO2 accumulates in alkaline fluids approximating those found in caterpillars, and whether joint consumption of O2 and CO2 can drive convective flows in insect tracheal tubes. The student will be responsible for developing and testing bio-inspired physical models constructed both at macroscales (from glass and metal) and microscales using a microfluidic fabrication system.
Supervisors: The student will be co-supervised by Dr. Casas and an American collaborator, Dr. H. Arthur Woods (University of Montana), who will provide hybrid supervision, via internet and also by spending an extended period of time with the student in Casas lab early in the project. Both supervisors have significant histories in insect physiology and have been collaborating on this project for the past two years (https://scholar.google.com/citations?user=9_Kga_kAAAAJ&hl=en&oi=ao and https://scholar.google.com/citations?hl=en&user=mGQtvV4AAAAJ ).
Background knowledge: biologists of all kinds but without mathematical phobia and engineers with ease in chemistry and wetware are welcome to apply. Previous experience with “bricolage”, being at home or at work can be a plus. Ability to work independently is required.
Knowledge gained through this formation: use of mathematical models, fabrication of microfluidic devices, respiratory and digestive physiology, insect organismal biology and interdisciplinarity.
Starting date, contact. We expect the student to start in January 2025 to fully use the onsite presence of Woods from Mid-February to end of March (approximate dates). Duration: min. 6 months. Please send application material (Cover letter, CV, names and e-mails of 3 referees) to casas@univ-tours.fr & Art.Woods@mso.umt.edu. Position open until filled.
