Worm Breeder's Gazette 15(2): 50 (February 1, 1998)

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.

dpy-20 gene affects the expression of unc-119 gene in the motor neurons, but not in the sensory neurons in C. elegans

F. Hori, M. Y. Ali, T. Matsuo, Shahid S. Siddiqui.

Lab. of Molecular Biology, Toyohashi University of Technology, Tempaku-cho, Toyohashi-441, Japan

Mutants in the  unc-119 gene are  defective in locomotion, feeding
behavior and chemosensation (Maduro M, Pilgrim D,1995). The unc-119 
gene expresses in many neurons including the cell bodies and processes
of several motor neurons in the nerve cord, pharyngeal region, and in
the tail lumbar ganglia, pre-anal ganglion and dorso-rectal ganglion, 
and the  male  sensory neurons; suggesting that the unc-119 mutants are
defective in most of  the nervous system. The expression of
unc-119::lacZ and GFP shows that the unc-119 gene is expressed shortly
before the  comma stage in embryogenesis  and continues during late
embryonic and post-embryonic development (Maduro M, Pilgrim D,1995). In
accompanying abstracts in this issue of WBG, we have shown that
the dpy-20 may encode a novel transcription factor that affects
transcription of various genes in the ventral cord motor neurons (Ali et
al.,  Shibata et al.,  Ali et al.  see abstracts in this WBG issue )

We have found that in the dpy-20(e2017) mutant background the expression
of the unc-119::lacZ  is reduced significantly in the ventral nerve cord
motor neurons, with little or no affect on the staining pattern of the
sensory neurons in the head or tail of the animals. In addition we have
observed ectopic expression of the unc-119 reporter gene in the vulval
region. These results suggest  that the  dpy-20 is affecting  expression
of the  unc-119 reporter gene in a select class of motor neurons as 
there is no effect on  the expression of unc-119 in the  touch neurons
and in the embryos. To test the effect of unc-119 mutation on the
expression of dpy-20 gene expression, we have done an experiment in
reverse, i.e.  studied expression of the  dpy-20::lacZ in unc-119(e2498)
mutant  background and found that there is a small effect of unc-119
mutant background on the expression of dpy-20. In the unc-119 mutant
background, about 20% animals show reduced staining in the ventral cord
motor neurons and also in the hypodermal cells. 

To study  genetic  interaction between the  dpy-20 and unc-119 loci, we
have constructed a double mutant  dpy-20(e2017);unc-119(e2498). The
dpy-20( e2017) is an amber allele (J. Hodgkin, 1985),  these  animals
are short in size but their  locomotion is quite  normal. On the other
hand,  unc-119(e2498) is an uncoordinated mutant, with abnormal
locomotion. Their double mutant is severely paralyze, and it fails to
produce eggs and ends up  as a bag of worms, and thus shows a  reduced
brood size. These observations are consistent with a model in which
dpy-20 gene mediates transcription of unc-119 gene, particularly in the
set of ventral cord motor neurons, but also suggests an additional role
in viability and brood size. Staining of the dpy-20 mutant alleles with
the nuclear staining dye DAPI reveals that these mutants are also
defective in germ line development (M. Y. Ali, Z. K. Siddiqui, and S. S.
Siddiqui). We are therefore studying the effect of dpy-20 mutations on
various genes which mediate germ cell development. The reporter gene
dpy-20::lacZ does not express in the germ line, so we are preparing
antibodies made against the DPY-20 protein expressed in E. coli (M. Y.
Ali, Z. K. Siddiqui, S. S. Siddiqui, unpublished) to examine the
localization of the DPY-20 protein in the wild type and mutant

We thank Morris Maduro and David Pilgrim for the unc-119::lacZ line and
mutant strains, David Baillie for his help and cooperation and T.
Stiernagle for the other mutant strains.