The kinetics of embryo drying in Drosophila melanogaster as a function of the steps in permeabilization: Theoretical

• Published in: Journal of insect physiology 1996, Vol.42 (6), p.603-615
• Main Authors: Schreuders, P.D., Kassis, J.N., Mazur, P.
• Format: Article
• Language: English
• Subjects: air drying; alcohols; chemical treatment; dechorionation; Drosophila melanogaster; embryo (animal); Embryo dehydration; Kinetic model; kinetics; membrane permeability; membranes; Permeability; Permeabilization protocol; physical models; removal; theory; water content; water loss
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/0022-1910(95)00125-5

Previously, we gravimetrically examined the Drosophila embryos' rate of air drying after each step in their permeabilization; namely, (1) dechorionation, (2) isopropanol exposure, and (3) heptane/butanol exposure. Here we describe a physical model characterizing the dehydration and compare the theory with the experimental kinetics. The model is based on those of Eyring. It treats the net flux ( J net) through the membrane as the sum of two opposing fluxes (air → embryo {a{ and embryo → air {i{. Each flux is the product of a kinetic constant ( k), the number of embryos in the sample (n), and the water concentration ( C). Thus, J net = k a nC a − k i nC i . The relationship between k i and k a , for embryos in steady state with room humidity, is k i k a = C a C i . Determining the k values requires the mass and density of the embryo solids, n, C i , as a function of drying time, and the steady-state value of C i . Following integration of the flux equation, linear regression was used to determine k i. k a was computed using the previous equation. The resulting values for k a are 3.96, 26.70, 17.40, and 258.00 mn 3/embryo·h for untreated embryos and embryos treated with, (1), (l) + (2), (l) + (2) + (3), respectively. The corresponding values for k i (×10 6) are 484, 3680, 2800, and 47,300 mm 3/embryo·h.