Figure 7.—

Muscle and axon defects in troponin I mutants. (A) bx124 and bx127 failed to complement unc-27(e155) and were rescued by cosmid ZK721. Both mutations consist of the same G-to-A mutation in a splice acceptor sequence of the predicted gene ZK721.2, which encodes troponin I and is thereby identified as unc-27. (B) Expression of an unc-27∷GFP reporter gene in embryonic and adult body-wall muscles and in adult male diagonal muscles. (C) Mutant muscle structure in unc-27. Normally elongated body-wall muscles have shortened, abnormal structures (arrowheads). (D) The ray neuron and other axons follow commissural pathways between the basal surface of the hypodermis and the underlying basement membrane. Distortion of these pathways in muscle mutants results in apparent wandering axon pathways.