Visualization of gene expression in Pristionchus pacificus with smFISH and in situ HCR

Single molecule fluorescence in situ hybridization (smFISH) and in situ hybridization chain reaction (HCR) have become powerful tools to visualize gene expression in many different animal species. We show here that smFISH and in situ HCR can be put to effective use in the satellite nematode model organism Pristionchus pacificus . Examining the expression of a homeobox gene ( Ppa-unc-30) , we found that HCR is more sensitive than smFISH. We confirmed the robustness of HCR by visualization of the expression of several genes involved in neurotransmitter synthesis or transport ( Ppa-unc-25 /GAD, Ppa-unc-17/VAChT, Ppa-eat-4 /VGLUT). Combined with its relative cost-effectiveness compared to smFISH analysis, in situ HCR constitutes a useful addition to the toolbox for P. pacificus research .