Development of the pulmonary surfactant system in the green sea turtle, Chelonia mydas

This study describes the developmental changes in pulmonary surfactant (PS) lipids throughout incubation in the sea turtle, Chelonia mydas. Total phos pholipid (PL), disaturated phospholipid (DSP) and cholesterol (Chol) harves ted from lung washings increased with advancing incubation, where secretion was maximal at pipping, coincident with the onset of pulmonary ventilation . The DSP/PL ratio increased, whereas the Chol/PL and the Chol/DSP ratio de clined throughout development. The phospholipids, therefore, are independen tly regulated from Chol and their development matches that of mammals. To e xplore whether hypoxia could elicit an effect on the development of the PS system, embryos were exposed to a chronic dose of 17% O-2 for the final sim ilar to 40% of incubation. Hypoxia did not affect incubation time, absolute , nor relative abundance of the surfactant lipids, demonstrating that the d evelopment of the system is robust and that embryonic development continues unabated under mild hypoxia. Hypoxia-incubated hatchlings had lighter wet lung weights than those from normoxia, inferring that mild hypoxia facilita tes lung clearance in this species. (C) 2001 Elsevier Science B.V. All righ ts reserved.