Worm Breeder's Gazette 15(1): 60 (October 1, 1997)

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.

Rescue of lin-18 by a predicted receptor tyrosine kinase.

Wendy S. Katz

Department of Biochemistry, University of Kentucky College of Medicine, Lexington KY 40536-0084.

We have observed rescue of lin-18(e620) by cosmids C16B8 and T19D2 in
germline transformation experiments, scoring gross anatomy under low
magnification.  At least two stable lines displaying more than 90% wild
type progeny were observed using each cosmid.  Rescue of secondary
lineage misorientation was confirmed by observation under Nomarski
optics.  Non-transgenic siblings displayed fewer than 50% wild type
progeny, consistent with previous observations of lin-18 phenotypes.

The region of overlap contains two predicted genes.  We performed
germline transformation experiments using PCR products that encompassed
each predicted gene, including 5 kb of upstream noncoding sequence.
Products of two independent PCR reactions containing C16B8.1 produced a
total of 3 lines that displayed 76% wild type progeny.  Non-transgenic
siblings displayed fewer than 45% wild type progeny.  We isolated 9
stable lines from parents injected with the product of a single PCR
reaction containing C16B8.2.  None displayed more than 45% wild type
progeny.  We are currently testing a C16B8.1 PCR product containing
more upstream noncoding sequence to test whether this product can
rescue to the same extent as the cosmid.  An alternate possibility is
that the injected DNA includes a small population of mutant PCR product
that exerts a dominant negative effect.  We are subcloning the PCR
product to test this possibility.

C16B8.1 encodes a predicted receptor tyrosine kinase that shares
approximately 28% and 25% amino acid sequence identity with the
products of the human ryk and Drosophila derailed genes, respectively
(1,2).  The function of Ryk is not known.  Derailed is required for
normal development of a small subset of nerves and muscles in the
Drosophila embryo (2,3).

1.  Hovens et al. (1992).  Proc. Natl. Acad. Sci. USA 89:11818-11822
2.  Callahan et al. (1995). Nature 376:171-174
3.  Callahan et al. (1996). Development 122:2761-2767