Affiliations 

  • 1 Assay Development Division, Malaysian Institute of Pharmaceuticals and Nutraceuticals, Ministry of Science, Technology and Innovations, Block 5-A, Halaman Bukit Gambir, Penang 11700, Malaysia
  • 2 School of Biological Sciences, Universiti Sains Malaysia, Minden, Penang 11800, Malaysia
  • 3 School of Biological Sciences, Universiti Sains Malaysia, Minden, Penang 11800, Malaysia; Center for Marine and Coastal Studies, Universiti Sains Malaysia, Minden, Penang 11800, Malaysia. Electronic address: alex@usm.my
Biochim. Biophys. Acta, 2015 Mar;1851(3):248-60.
PMID: 25542509 DOI: 10.1016/j.bbalip.2014.12.012

Abstract

The endogenous production of long-chain polyunsaturated fatty acids (LC-PUFA) in carnivorous teleost species inhabiting freshwater environments is poorly understood. Although a predatory lifestyle could potentially supply sufficient LC-PUFA to satisfy the requirements of these species, the nutrient-poor characteristics of the freshwater food web could impede this advantage. In this study, we report the cloning and functional characterisation of an elongase enzyme in the LC-PUFA biosynthesis pathway from striped snakehead (Channa striata), which is a strict freshwater piscivore that shows high deposition of LC-PUFA in its flesh. We also functionally characterised a previously isolated fatty acyl desaturase cDNA from this species. Results showed that the striped snakehead desaturase is capable of Δ4 and Δ5 desaturation activities, while the elongase showed the characteristics of Elovl5 elongases. Collectively, these findings reveal that striped snakehead exhibits the genetic resources to synthesise docosahexaenoic acid (DHA; 22:6n-3) from eicosapentaenoic acid (EPA; 20:5n-3). Both genes are expressed at considerable levels in the brain and the liver. In liver, both genes were up-regulated by dietary C18 PUFA, although this increase did not correspond to a significant rise in the deposition of muscle LC-PUFA. Brain tissue of fish fed with plant oil diets showed higher expression of fads2 gene compared to fish fed with fish oil-based diet, which could ensure DHA levels remain constant under limited dietary DHA intake. This suggests the importance of DHA production from EPA via the ∆4 desaturation step in order to maintain an optimal reserve of DHA in the neuronal tissues of carnivores.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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