Localized RNAi and ectopic gene expression in the medicinal leech

Area of Science:

• Developmental Biology
• Molecular Biology
• Bioengineering

Background:

• Accurate delivery of reagents into live tissues is crucial for perturbing gene expression.
• Existing methods like microinjection or systemic approaches have limitations in targeting specific cells.
• Need for a precise, non-destructive method for localized gene manipulation in early developmental stages.

Purpose of the Study:

• To demonstrate the efficacy of a pneumatic capillary gun for biolistic delivery of reagents into live leech embryos.
• To utilize this method for targeted gene knockdown and expression analysis.
• To establish a precise delivery system for studying gene function in specific cell populations.

Main Methods:

• Utilized a pneumatic capillary gun for biolistic delivery of dsRNA or plasmid DNA.
• Coated particles with reagents (dsRNA for Netrin knockdown, plasmid DNA for EGFP expression).
• Delivered particles into specific tissues (body wall, central ganglia) of leech embryos.
• Analyzed results via immunostaining, immunohistochemistry, and neuronal labeling 2-3 days post-delivery.

Main Results:

• Achieved accurate, localized delivery of reagents into internal cell layers without specimen dissection.
• Netrin dsRNA delivery resulted in visible Netrin expression knockdown specifically in targeted cells.
• EGFP-encoding plasmid delivery induced fluorescence in neuronal cells, confirming successful gene expression.

Conclusions:

• The pneumatic capillary gun provides a fast, contact-free, and non-destructive method for precise biolistic reagent delivery.
• This technique enables targeted gene manipulation (knockdown/knock-in) at the cellular level in developing organisms.
• The method offers an intermediate approach between single-cell microinjection and systemic genetic manipulation.