Worm Breeder's Gazette 14(1): 40 (October 1, 1995)

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Pharyngeal specific expression of the tropomyosin gene tmy-1 of C. elegans

Kyoko Takuwa, Hiroaki Kagawa

Okayama University, Faculty of Science Okayama, Japan 700 hkagawa@cc.okayama-u.ac.jp

     The tropomyosin gene tmy-1 of C. elegans spans 14 kb and encodes
three isoforms CeTMI, CeTMII and CeTMIII with 14 exons.  Tissue
specific expression of the tmy-1 gene was determined by microinjection
of promoter/lacZ fusion plasmids.  The 5'end promoter common to CeTMI
and CeTMII control expression in the body wall, vulva, anus and male
tail muscles.  Interestingly expression of CeTMIII was transspliced
with SL1. The internal promoter in intron 3 controls the expression
CeTMIII in the pharyngeal muscles1).  Map position of tmy-1 locates on
the lev-11 site1). Determination of the mutation site in the
tmy-1/lev-11 gene will help to know how signal from troponin could
reach to actin filament through tropomyosin.
     C-element for cell specific and B element a putative ceh-22
binding site for tissue specific expressions control the pharynx
specific expressing of the myo-2 gene2).  We found B element in intron
4 (8100-8135) and two C-elements in intron 3 (5185-5219; 7466-7494) of
the tmy-1 gene.  Deleting BglII fragment including one of C-element
from pTMIZ3256 (4583-8277) had little effect on expression in the
pharynx.  Myo-2 B sub-element could function on the tmy-1 gene
expression in the pharynx.  We are constructing the fusion plasmids to
know which regions exactly control the tissue specific expression.
     On the contrary to the tmy-1 gene, unc-15 the paramyosin gene
encodes only one isoform and expresses in the pharynx and the body
wall muscles.  There was a promoter like sequence in the 5' end of the
gene and contained a putative enhancer sequence in intron 5 which
could form a stem and loop structure.  We have not isolated a
pharyngeal specific unc-15/lacZ fusion plasmid yet.
The tmy-1 and unc-15 genes are a good example for studying how one
gene was controlled with a different expression mechanism.

myo-2 B sub-element
tmy-1  AAGTGGcTGctcctgctGctTAtttGTcttAgAATa (17/31)
myo-2 C  sub-element

tmy-1  TCTCtaTGTTTGtaGagaGGcTGggcGCC   (18/28)   7466-7494

tmy-1  aCgaGaTGTTTGCtttacaacaaCtccTccCcGCC (15/28) 5185-5219

1) Kagawa et al, J. Mol. Biol. 1995, 251(5),603-613.
2) Okkema & Fire, Development, 1994, 120, 2175-2186.