The
unc-73 gene of C. elegans plays a role in controlling cell polarity. Animals mutated in this gene are severely uncoordinated due to incorrect axon guidance. We found that they also exhibit defects in cell migration and asymetric cell division (Way et. al, 1992). The coordinated revertants of
unc-73(
e936) we isolated include intragenic suppressors and extragenic dominant suppressors
sup-39(
je5 or
je6).
sup-39 mutations alone have a wild-type movement as larvae and adults. However, they have the following novel and dominant phenotypes with incomplete penetrance: 1) Maternal embryonic lethality. The lethality decreases when the mother's age increases; 2) Two instead of one row of oocytes in each gonad arm; 3) Left-handed Roller after L4 stage, which is much enhanced when synthetic with
je11, a spontaneous mutation. These results suggest that the
sup-39 mutations probably have effects in many cell-polarity events, especially in axon guidance, in choosing a single site on the gonad from which oocyte nuclei will emerge, and in the polar secretion of cuticle. However,
sup-39 does not suppress the weak defect of asymmetric
mec-3 expression in
unc-73 mutant.
sup-39 was mapped between
dpy-10 and
cdc-42 and within 0.015 map units of
unc-104(II). Thus far, no recessive alleles of
sup-39 has been isolated, perhaps because of haplo-insufficiency of this gene (Run et.al, 1996). To further understand the role of
unc-73 and
sup-39 in controlling cell polarity, we plan to clone
sup-39 by using the following strategies: 1) Get a more accurate position of
sup-39(
je5) by using Tc1 transposons in Bergerac strains as markers; 2) Detect the position of
sup-39 mutation in potential coding sequences by examining single-strand polymorphism of cDNA produced by
unc-104 and its surrounding genes from N2 and
sup-39 mutants; 3) Create a genomic library from
sup-39(
je5) , find cosmids around
unc-104, and then find a cosmid which will suppress
unc-73(
e936). Way, J. C. et. al (1992) Developmental Dynamics 194: 289-302. Run, J. Q. et. al (1996) Genetics (May)