In vivo detection of ALFA-tagged proteins in C. elegans with a transgenic fluorescent nanobody

To track tagged endogenous proteins in vivo , we created a C. elegans strain expressing a fluorescently-labelled nanobody directed against the ALFA-tag epitope. The strain, which expresses an anti-ALFA nanobody fused to mKate2, is healthy and allows clear detection of the ALFA-tagged junction protein DLG-1 at all stages. This method is adapted for live imaging, circumvents the need of immuno-histochemistry, and opens perspective to study protein function in vivo . The future detection of sensitive proteins can therefore be envisaged in nematodes by using transgenic nanobodies, or chromobodies, in combination with ALFA-tagging by CRISPR.