Putative null allele which lacks whole of the 3rd exon of the gene (lacking 260 bp area corresponding to 12984-13243 of the cosmid F13G3). Severe thermotaxis defect. Weak defects in chemitaxis. Subcellular localization of SNB-1::GFP is abnormal in RIA interneurons.

Excretory canal defect. Large fluid-filled cysts appear randomly along the excretory canal, especially at the tips. 100% penetrant. Cysts often visible as clear spots by low-power microscopy.