Muscle gene defects disrupt the filament assembly, development and coordinate movement of the animal. In C. elegans, two muscle tissues, pharynx and body walls are thought a model for studying tissue specific gene expression and calcium signaling. Two of each myosin heavy chain genes are specifically expressed in the both tissues by the control of promoters and enhancers. We present the results of the genome structures and tissue specific expression of the tropomyosin gene, tmy-l (levl l ); I, two troponin I genes, tni-l,
tni-2; X and troponin C gene tncl(
pat-10); I. Constructed promoter/lacZ fusion plasmids were injected into the worm and B-Gal activity was detected with X-gal treatment. Troponin genes, tnc-l, tni-l and
tni-2 encoding only one transcript respectively were specifically expressed in the body wall muscles. Two troponin I genes were expressed in the body walls at the different rate by the reason of promoter activity. Two of three isoformes of tmy-l were expressed in the body walls under the control of the 5'UTS and the third was expressed in the pharynx by the second promoter locating in the third intron. The paramyosin gene,
unc-15 encoding one transcript was expressed in the both tissues by the control of promoter and enhancer. The results of these tissue specific localization of the gene products were also confirmed with immunohistochemistry (Takuwa et al). These results on the muscle proteins combined together show that the molecular ratio in the muscle filaments may be controlled at the transcription rate and the pharynx may be controlled by calcium signaling like as a smooth muscle in vertebrates.