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.
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). References: 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