Desaturase Delta-6 mRNA Expressions In Highly Unsaturated Fatty Acids Biosynthesis Pathway During Follicle Maturation In Female Zebrafish (Danio rerio)
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Date
2010-06
Authors
Ishak, Sairatul Dahlianis
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Very little is known about the synthesis of unsaturated fatty acids such as
eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3) and
arachidonic acid (ARA, C20:4n-6), or collectively known as the highly unsaturated
fatty acids (HUF A), in the fish ovary although they play pivotal roles in this
vertebrate reproduction. The zebrafish (Dania rerio) display capability to synthesize
all three HUF A via pathways involving desaturation and elongation of two
precursors, the linoleic acid (LA, C18:2n-6) and linolenic acid (LNA, Cl8:3n-3). In
order to gain understanding on the importance and regulation of ovarian HUF A
synthesis, this study shows the mRNA expression pattern of desaturase (jadsd6), an
essential enzyme involved in HUF A biosynthesis pathway, in five different zebrafish
ovarian follicle stages; pre-vitellogenic, early vitellogenic, late vitellogenic,
maturation and ovulation stages. The mRNA levels of fadsd6 in different ovarian
follicle stages were determined by semi-quantitative RT-PCR assays. Concurrently,
the fatty acid profile of each follicle stage was also analysed using gas
chromatography. Results of RT-PCR assays have shown that desaturase displayed
significant upregulation in expression during the oocyte maturation stage compared
to the other follicle stages. At the same time, fatty acid composition analysis of
different ovarian follicle stages also showed that ARA level was significantly highest
in pre-vitellogenic and matured follicles. DHA level was highest in both late
vitellogenic and maturation stage. Collectively, the findings seem to suggest the
existence of a HUF A synthesis system, which could be responsible for the synthesis
of HUF A to promote oocyte maturation and possibly ovulation processes. The many
advantages of zebrafish as model system to understand folliculogenesis will be useful
platform to further elucidate the regulatory and mechanism aspects of ovarian HUF A
synthesis.
Description
Keywords
The synthesis of unsaturated fatty acids , in the fish ovary.