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Published on: March 29, 2019
Efficient Gene Expression System in Medaka Embryos Enables Functional Characterization of nt5c1a Paralogs Involved in
Yu Murakami1, Tomohisa Horibe2, Masashi Ando1
1Department of Fisheries, Graduate School of Agriculture, Kindai University, Nara, Japan.
Genesis (New York, N.Y. : 2000)
|May 9, 2026
Summary
We optimized fish embryo gene expression for rapid analysis. This system revealed how a specific mutation in cytosolic 5’-nucleotidase 1a (nt5c1a) affects umami flavor compound metabolism, aiding molecular breeding for enhanced taste.
Area of Science:
- * Aquaculture and Molecular Biology
- * Fish Embryo Gene Expression Systems
Background:
- * Transient gene expression in fish embryos is vital for understanding gene function quickly.
- * Cytosolic 5’-nucleotidase 1a (nt5c1a) plays a role in metabolizing inosine monophosphate (IMP), a key umami flavor compound.
Purpose of the Study:
- * To establish an efficient transient gene expression system in medaka (Oryzias latipes) embryos.
- * To investigate the functional divergence of medaka nt5c1a paralogs (nt5c1aa and nt5c1ab) and their role in IMP metabolism.
- * To identify key residues responsible for functional differences between nt5c1a paralogs.
Main Methods:
- * Optimization of nucleic acid type and injection site for transient expression in medaka embryos.
- * In silico and structural analysis (AlphaFold) of medaka nt5c1a paralogs.
- * Functional assays to assess IMP degradation activity.
Main Results:
- * Injection of elongation factor 1αA (ef1αA) promoter-driven plasmid into the yolk of medaka embryos resulted in optimal expression.
- * Medaka possesses two nt5c1a paralogs: nt5c1ab (functional) and nt5c1aa (non-functional due to L305P mutation).
- * The L305P mutation in Nt5c1aa causes local conformational changes affecting substrate binding; partial restoration of IMP degradation was observed upon mutation correction.
Conclusions:
- * An optimized transient expression system in medaka embryos was successfully established.
- * The L305P substitution is identified as a critical determinant for the functional divergence of nt5c1a paralogs.
- * Findings support molecular breeding strategies to enhance umami flavor in farmed fish by manipulating nt5c1a paralogs for increased IMP accumulation.
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