Comparison of the fatty-acid compositions of prey items and yolks of Australian insectivorous scincid lizards
- PDF / 188,908 Bytes
- 5 Pages / 595 x 785 pts Page_size
- 61 Downloads / 179 Views
O R I GI N A L P A P E R
Brian K. Speake Æ Jacquie F. Herbert Michael B. Thompson
Comparison of the fatty-acid compositions of prey items and yolks of Australian insectivorous scincid lizards
Published online: 14 April 2004 Springer-Verlag 2004
Abstract The yolk fatty-acid profiles of a range of species of insectivorous scincid lizards generally conform to a common pattern, typified by high proportions of linoleic acid (13.5–18.5% of total fatty acids), substantial proportions of a-linolenic acid (2.4–8.2%), and significant amounts of the long-chain polyunsaturated fatty acids, arachidonic (1.6–3.3%), eicosapentaenoic (0.7–1.2%) and docosahexaenoic (0.7–1.6%) acids. We characterised the fatty-acid compositions of ten prey taxa that are eaten by female skinks during vitellogenesis. Linoleic acid is the major polyunsaturated fatty acid in all prey, excepting Orthoptera where a-linolenic acid predominates. To varying extents, a-linolenic acid is present in all the prey items. Arachidonic acid forms over 1% of total fatty acids for six of the prey items. Four of the prey items contain eicosapentaenoic acid at over 1%. Most notably, docosahexaenoic acid is essentially absent from all the prey items. There is a general similarity between the fatty-acid profiles of prey and yolk, suggesting that the linoleic, a-linolenic, arachidonic and eicosapentaenoic acids required for egg formation can be supplied directly from the maternal diet. However, the docosahexaenoic acid of the egg lipids cannot derive from the diet and must, therefore, be formed by biosynthesis in the maternal liver, using dietary a-linolenic and eicosapentaenoic acids as precursors.
B. K. Speake Avian Science Research Centre, SAC, Auchincruive, Ayr, KA6 5HW, UK J. F. Herbert Æ M. B. Thompson (&) School of Biological Sciences and Wildlife Research Institute, University of Sydney, Zoology Building (A08), NSW 2006 Sydney, Australia E-mail: [email protected] Tel.: +61-2-93513989 Fax: +61-2-93514119
Keywords Lizard Æ Yolk Æ Lipid Æ Polyunsaturated fatty acid Æ Insect
Introduction Eggs laid by oviparous lizards must contain all the nutrients required to sustain the development of the embryo to the time of hatching. Lipids, especially triacylglycerol and phospholipid, are major constituents of the yolks of scincid lizards, and the fatty-acid components of these lipids perform essential functions during development of the embryo (Speake and Thompson 2000). Fatty acids are the main energy source for embryonic development and are also the precursors for the biosynthesis of phospholipids that form the cell membranes of the growing tissues (Thompson and Speake 2003). Also, fatty acids derived from yolk lipids are used to lay down fat stores in the embryo, providing an energy reserve for the neonate (Speake and Thompson 2000). Although viviparity has evolved in several lineages of the Scincidae, many of these viviparous species are predominantly lecithotrophic, relying almost entirely on the contents of the retained egg to provide organic nutrients to the fetus
Data Loading...
