Worm Breeder's Gazette 11(1): 37
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.
Cell to cell communication is thought to be very important for a multicellular organism. Tyrosine kinases have been found in various multicellular organisms, but none in unicellular organisms. Tyrosine kinase domains are often found in the receptors of a long-range signal (EGF receptor, insulin-receptor etc.) or short-range signal (sevenless, which recognizes a molecule presumably bound on the cell surface). These facts may suggest that a tyrosine kinase is one of the key molecules in evolution from unicellular to multicellular organization. Another family of molecules such as lin-12 and notch are also known, which control development probably by interacting with neighboring cells. These molecules have extracellular EGF motif repeats and a trans-membrane domain. It could be speculated that lin-12 or notch is recognized by a receptor-type tyrosine kinase as EGF is recognized by the EGF-receptor. From the viewpoint stated above, we tried cloning tyrosine kinase genes from C. elegans. An N2 genomic library from Dr. C. Link was screened with a C-terminal 0.75 kb fragment of v-ros oncogene as a probe. Six kinds of hybridizing clones were obtained, and they were partially sequenced. One clone was identical to N-abl (named abl-1 on the physical map) which was reported by Goddard et al., Proc. Natl. Acad. Sci. 83, 2172-2176 (1986). The other five carried putative coding sequences for a tyrosine kinase domain as reviewed by Hanks et al., Science, 241, 42-52 (1988). These clones were mapped on the physical map by Drs. J. Sulston and A. Coulson, and named kin-5, kin-7, ed between msp-77 and col-2 ( Chromosome IV ), kin-6 between sqt-1 and gpb-1 (II), kin-9 between rtm-3 and sup-28 (X), kin-7 and kin-8 between TCROL6 and eP43 ( II). The distance from kin-7 to kin-8 corresponds to 30 HindIII sites. Let-23 sits around here (personal communication from Dr. Paul Sternberg). We made Northern blot analysis of poly A RNA from a C. elegans mixed population, using genomic DNAs from kin-5, 6, 7 and abl- 1 as probes. Kin-7 detected a strong band of about 4.3kb, and abl-1 detected a quite similar band. Kin-5 and 6 did not detect any band so far. We also obtained cDNA clones corresponding to kin-5, 6, 7, 8 and abl-1 from cDNA library from Dr. B. Barstead. Now, we are trying to localize these genes on the genetic map by Southern blot hybridization of the DNA from deficiency strains. Then, we will try to identify mutants for these genes among already mapped mutants with Southern blotting, Northern blotting or PCR. [See Figure 1]