Lipid provisioning of turtle eggs and hatchlings: total lipid, phospholipid, triacylglycerol and triacylglycerol fatty acids

Abstract

Lipid composition of eggs and hatchlings was studied in painted, snapping and Blanding's turtles from western Nebraska. The average total lipid proportions of the egg yolk, post-embryonic yolk and hatchling soma dry masses were high in painted turtles (29.80%, 42.16% and 14.18%, respectively) relative to snapping and Blanding's turtles (egg yolk < 14%, postembryonic yolk < 17%, hatchling soma < 2%). The proportion of total egg yolk lipid used during development varied among species (painted turtles, x = 45.4%; snapping turtles, x = 68.9%; Blanding's turtles, x = 86.6%). Total lipid data are consistent with patterns reported for turtle species whose hatchlings overwinter in the nest (e.g., painted turtles) vs those whose hatchlings emerge in the fall (e.g., snapping and Blanding's turtles). In all species, the total lipid quantity of egg and hatchling components was primarily triacylglycerol (> 63%), an energy storage form. Predominant triacylglycerol fatty acids in eggs and hatchlings were 16:0, 16:1 and 18:1, and concentration changes of some yolk fatty acids occurred during development. The average phospholipid (a membrane form) quantity of the egg and hatchling components was relatively low in painted turtles (< 2% of the total lipid). In snapping and Blanding's turtles, the relatively large phospholipid proportion of the post-embryonic yolks (approximately 7%) could potentially contribute more to post-embryonic growth in these species than the phospholipids of painted turtle post-embryonic yolks.