See through Casper danio helps cell biologists

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Medical researchers in Boston have created a transparent zebrafish (Danio rerio) strain that allows them to study stem or tumour cell engraftment.

The new strain is named casper by Richard White and fellow researchers in the latest issue of the journal Cell Stem Cell.

Casper is a double homozygous mutant resulting from a cross between the nacre mutant, which lacks melanocytes (pigment-bearing cells), but possesses iridiophores (reflective cells) and the Roy Orbison mutant, which possesses melanocytes (albeit in a severely disrupted pattern), but lacks iridiophores.

According to the authors the transparency of the casper mutant is due to a combination of melanocyte loss (which normally absorbs incident light and protects subdermal structures) and iridiophore loss (which normally reflect incident light away from the internal organs).

The transparency of the fish allows researchers to better study stem cell and tumour biology by making it easier for in vivo imaging of stem or tumour cells grafted onto the fish.

The authors write: The data presented here demonstrate that the optical properties of the casper fish offers a unique combination of high resolution (~5 mm), sensitivity, and amenability to deep tissue imaging with commonly available laboratory equipment. Although similar to the ~~see through medaka strain, the zebrafish has become a more commonly utilized tool for studying stem cell and tumor biology and should be broadly applicable to stem cell researchers.

For more information, see the paper: White, RM, A Sessa, C Burke, T Bowman, J LeBlanc, C Ceol, C Bourque, M Dovey, W Goessling, CE Burns and LI Zon (2008) Transparent adult zebrafish as a tool for in vivo transplantation analysis. Ceel Stem Cell 2, pp. 183"189.