Worm Breeder's Gazette 15(3): 24 (June 1, 1998)

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.

Overexpression of a novel protein causes chromosome nondisjunction in Caenorhabditis elegans

Lynnette M. Kuervers, Diana L. Janke, David L. Baillie

Institute of Molecular Biology and Biochemistry, 8888 University Dr., Simon Fraser University Burnaby, B.C., V5A 1S6, Canada

 

Our lab has generated a cosmid transgenic library in order to rescue a number of essential genes on chromosome III (Janke et al 1997). We reported the discovery of a him phenotype exhibited by two separate transgenic lines containing either overlapping cosmid F56D2 or C05D2. Subsequent to this observation, we reproduced this phenotype by injecting subclones of this 25kb overlap region into C. elegans. All evidence suggests that this phenotype is the result of the overexpression of C05D2.5. BLAST searches have failed to discover any significant matches, thereby indicating that C05D2.5 is a novel protein. In addition, Yuji Kohara has isolated four cDNAs corresponding to this gene

We are interested in discovering the role of this protein in chromosome segregation. Depending on the copy number of C05D2.5, between 2% and 25% self-progeny males are produced. At 20 C we have failed to observe jackpots of males. This nondisjunction effect does not appear to be temperature sensitive. In accordance with the increase in self progeny males, there is an increase in embryonic lethality consistent with autosomal nondisjunction. We have also shown that nondisjunction occurs in the oocyte line and most probably the spermatocyte line. Interestingly, the nondisjunction effect is perpetuated for at least three generations subsequent to losing the extrachromosomal array. There is a decrease in male production and an increase in brood size with each successive generation.

 

We are in the process of making a GFP fusion construct to observe the expression pattern of C05D2.5. We are also planning to introduce a frameshift mutation in order to prove that the nondisjunction is due to the overexpression of the C05D2.5 protein rather than the DNA or RNA. We are testing whether him-10 is a mutation in this gene since it maps within the area containing C05D2 (thank-you to the CGC for the strains). We believe the investigation of this gene will provide insights into the control of chromosomal nondisjunction in C. elegans.

 

Janke, D. L. et al. (1997) Interpreting a Sequenced Genome: Toward a Cosmid Transgenic Library of Caenorhabditis elegans. Genome Research 7974-7985.