Worm Breeder's Gazette 12(5): 78 (February 1, 1993)
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.
In a previous Gazette (12(3):62,1992), we reported on the cloning and characterization of ubc-2 ,the gene encoding a ubiquitin-conjugating enzyme (E2). To analyze the expression pattern of ubc-2 ,we transformed ubc-2 /LacZfusions into £. elegans. Interestingly, differences in the distribution of expression were observed between larvae and adults.
The first construct which was successfully expressed is pZM2 .It has LacZ inserted in frame into the second exon of ubc-2 .The expression of pZM2 was constitutive at all stages of development from early blastula onward. In all larval stages, intense X-gal staining was found in the nervous system (including the nerve ring, preanal ganglion and the ventral nerve cord), hypodermis, muscle, vulva, and pharynx. In contrast, the expression was much more limited in adults where most of the staining was found in the nervous system, P-cell lineage, and a few hypodermae cells in the head and tail. We also injected another construct, pZM3 ,which includes 8200bp of ubc-2 upstream sequence. Its expression pattern is similar to that of pZM2 .The consistent and overwhelming expression of pZM2 / pZM3 in the nervous system suggests an important involvement of ubiquitin-mediated protein degradation in neuronal activity.
The yeast homologs of ubc-2 , UBC4 and UBC5 ,are heat-inducible (EMBO J. 9:543-550,1990). However, Northern analysis suggested that the transcript level of ubc-2 was not affected by 1-2 hrs heatshock in C. elegans (Zhen et al, Mol. Cel. Biol. 1993, in press). We heat-shocked 7 transgenic lines carrying either pZM2 or pZM3 at 33°C, and assayed ß-galactosidase activity using ONPG. No increase in the activity was found after 2 hrs of heat treatment, in agreement with the results of the Northern blots. After a 4-6 hrs heat-shock, however, ß-galactosidase activity was slightly increased (20-50%).
Currently, we are trying to confirm the expression pattern of ubc-2 by in situ immunolocalization. To investigate the function of ubc-2 in C. elegans development, we are also trying to generate a ubc-2 null mutant.
Supported by the Medical Research Council of Canada and the B.C.
Health Research Foundation.