Ontogenic Expression And Characterization Of The Longchained Polyunsaturated Fatty Acid Biosynthesis Enzyme, Elongase In Zebrafish

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Date
2012
Authors
Tan, Sze Huey
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Universiti Sains Malaysia
Abstract
The importance of long-chained polyunsaturated fatty acids (LC-PUFAs) in vertebrates’ development has been widely studied. Among these, include roles in maintaining cellular membrane integrity, cellular signaling, gene regulation and metabolism. LC-PUFAs such as arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid also mediate physiological processes like inflammation, immunity, reproduction and development. Despite the known importance of LCPUFAs during development, very little is known about their utilization and biosynthesis during embryogenesis. Zebrafish embryos possess distinct advantages as model organism in developmental biology, including the ease of visualization, the availability of large numbers of offspring coupled with the existing molecular methods and tools. LC-PUFAs are synthesized via alternating desaturation and elongation steps with the key enzymes: desaturase and elongase. This present study describes the expression and functional characterization of two family members of elongases, elovl5 and elovl2 in zebrafish embryogenesis. elovl5 is significantly expressed at highest level at initial embryogenic stage which imply the maternal transfer process. Conversely, elovl2 is expressed at low level at initial stage and gradually elevated as embryo developed. Spatially, both elovl5 and elovl2 are found expressed in brain as early as 24hpf. However, as the embryos develop, they displayed distinct spatial expression. elovl5 is specifically expressed in pronephric tubules and yolk syncytial layer while elovl2 predominantly expressed in liver and intestine. In addition, profiling of fatty acids shows a general decrement of the substrates and increase of the LC-PUFAs as the embryo develops, which match the increasing expression of both elongases. Functional characterization of both genes was elucidated using knockdown approach. Knockdown of elovl5 and elovl2, respectively produced microcephaly embryos at early embryonic stage and eventually pericardial and yolk sac edema developed. In elovl5 knockdown, there seems to be no effect on pronephric development as intact segmentation of the pronephric tubules in morphants was confirmed by in situ hybridization using corresponding markers.
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Keywords
The longchained polyunsaturated fatty acid , biosynthesis enzyme, elongase in zebrafish
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