title: A two-step method for permeabilization of Drosophila eggs.
abstract: As a first step in developing a procedure for the cryopreservation of Drosophila melanogaster embryos, we have established a method for permeabilization of the eggcase and have initiated studies of the hydraulic conductivity of permeabilized embryos and the permeation of selected cryoprotective agents. The eggcase of D. melanogaster embryos has a wax layer that precludes any flux of water. A two-step procedure employing organic solvents was developed to effect removal of the wax layer with minimal deleterious effects on the embryos. Dechorionated embryos (Oregon-R strain P2, 12 to 13 hr old) were rinsed sequentially in isopropanol and hexane. After removal of solvent, embryos were held in a modified cell culture medium for further manipulation. This procedure routinely yielded 80 to 95% of the eggs permeabilized (as determined by osmotic contraction in 1 M sucrose) and 75 to 90% survival (incidence of hatching). Hydraulic conductivity of permeabilized embryos and permeation of cryoprotectants were determined using a microdiffusion chamber and computerized video microscopy. Regression analysis of the volumetric data from individual embryos yielded the Boyle-van't Hoff function FVeq = 0.124 (osm-1) + 0.541 with the standard deviations of slope and intercept (Vb) being 0.010 and 0.040, respectively. Permeabilized embryos exhibited ideal osmotic behavior over the range of 0.265 to 2.00 osm. The mean hydraulic conductivity coefficient (Lp) was 0.722 +/- 0.366 micron/(min.atm) at 20 degrees C, based on observations of contraction following a step change in concentration of Ringer's solution.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Agronomy, Cornell University, Ithaca, New York 14853.
authors.forename: D V
authors.initials: DV
authors.lastname: Lynch
authors.forename: T T
authors.initials: TT
authors.lastname: Lin
authors.forename: S P
authors.initials: SP
authors.lastname: Myers
authors.forename: S P
authors.initials: SP
authors.lastname: Leibo
authors.forename: R J
authors.initials: RJ
authors.lastname: Macintyre
authors.forename: R E
authors.initials: RE
authors.lastname: Pitt
authors.forename: P L
authors.initials: PL
authors.lastname: Steponkus
mesh_terms: D000433:1-Propanol / Q000494:pharmacology; D000818:Animals; D002463:Cell Membrane Permeability; D015925:Cryopreservation; D003451:Cryoprotective Agents / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology*; D006586:Hexanes / Q000494:pharmacology; D007700:Kinetics; D009997:Osmotic Pressure; D010063:Ovum / Q000187:drug effects / Q000502:physiology*; D014021:Tissue Preservation
chemical_list: D003451:Cryoprotective Agents; D006586:Hexanes; D000433:1-Propanol