Phosphatidylcholine composition of pulmonary surfactant from terrestrial and marine diving mammals

Abstract

Marine mammals are repeatedly exposed to elevated extra-thoracic pressure and alveolar collapse during diving and readily experience alveolar expansion upon inhalation – a unique capability as compared to terrestrial mammals. How marine mammal lungs overcome the challenges of frequent alveolar collapse and recruitment remains unknown. Recent studies indicate that pinniped lung surfactant has more anti-adhesive components compared to terrestrial mammals, which would aid in alveolar opening. However, pulmonary surfactant composition has not yet been investigated in odontocetes, whose physiology and diving behavior differ from pinnipeds. The aim of this study was to investigate the phosphatidylcholine (PC) composition of lung surfactants from various marine mammals and compare these to a terrestrial mammal. We found an increase in anti-adhesive PC species in harp seal (Pagophilus groenlandicus) and California sea lion (Zalophus californianus) compared to dog (Canus lupus familiaris), as well as an increase in the fluidizing PCs 16:0/14:0 and 16:0/16:1 in pinnipeds compared to odontocetes. The harbor porpoise (a representative of the odontocetes) did not have higher levels of fluidizing PCs compared to dog. Our preliminary results support previous findings that pinnipeds may have adapted unique surfactant compositions that allow them to dive at high pressures for extended periods without adverse effects. Future studies will need to investigate the differences in other surfactant components to fully assess the surfactant composition in odontocetes.

Effect of including herbal choline in the diet of a dairy herd; a multiyear evaluation

“…Choline has protective functions of the mitochondria, increases cellular antioxidant capacity, decreases triglycerides in liver cells, and promotes lipid catabolism and the elimination of radicals (Zhu et al, 2014). In addition, choline and its metabolites perform other functions, participating as a methyl donor and in the synthesis of acetylcholine and phosphatidylcholine (PCho) and phosphatidylserine (Finkelstein, 2000); PCho is the main phospholipid in cell membranes throughout the body (Li and Vance, 2008), PCho participates in the synthesis and export of triglycerides in very low-density lipoproteins (VLDL) in the liver (Zeisel, 2006) and PCho is required for the synthesis of dipalmitoyl-phosphatidylcholine, the main active surfactant component on the surface of the lungs (Gutierrez et al, 2015). PCho is also a precursor of sphingomyelin (Tayebati et al, 2015).…”

Respiratory function and mechanics in pinnipeds and cetaceans

“…Taken together, these differences are interesting and may indicate biochemical differences in the lung surfactants between species (Spragg et al, 2004;Miller et al, 2005Miller et al, , 2006aGutierrez et al, 2015), an active role of bronchial myoelastic sphincters (Kooyman, 1973;Kooyman and Sinnett, 1979;Ninomiya et al, 2005;Piscitelli et al, 2013) and/or variation in lung architecture such as collateral ventilation (see Glossary;Fahlman et al, 2011). During preliminary experiments in the excised lungs of a harbor seal, a white-sided dolphin and a pilot whale, we noted the possibility of collateral ventilation in the cetaceans but not in the seal (A.F and M.J.M., unpublished observation).…”

Intrinsic anti-inflammatory properties in the serum of two species of deep-diving seal

“…Remarkably, despite repeated trips to depths that induce lung collapse and re-expansion, diving seals do not display evidence of significant lung injury (Kooyman and Ponganis, 1998). This may in part be due to having a pulmonary surfactant with low surface activity (Miller et al, 2006a) that acts as an anti-adhesive surfactant promoting alveolar opening upon lung re-expansion (Foot et al, 2006;Gutierrez et al, 2015;Miller et al, 2006b;Spragg et al, 2004). However, the mechanisms that protect against tissue injury and/or cytokine production following atelectrauma and IR remain to be investigated.…”