The
twk-7 promoter drives DsRed reporter expression in some head and tail neurons as well as in all A-, B-, and AS-type motor neurons of the ventral nerve cord. In addition, DsRed expression was seen in GFP negative neurons. According to their number and stereotypic position, these TWK-7-expressing cells were identified as the 13 ventral and 6 dorsal GABAergic D-type motor neurons of the ventral nerve cord. The cell-type-specific expression pattern of TWK-7 was confirmed in worms that express a C-terminal tagged TWK-7::mCherry fusion protein under the control of the
twk-7 promoter. TWK-7::mCherry was localized along the ventral nerve cord and in punctated structures in the soma of motor neurons. Taken together, in accordance with the unraveled impact of TWK-7 on locomotor activity of C. elegans, TWK-7 is expressed in all types of motor neurons of the ventral nerve cord that control body-wall muscle activity.