Worm Breeder's Gazette 15(1): 35 (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.
Bernhard Nocht Institute for Tropical Medicine, Bernhard Nocht Str. 74, 20359 Hamburg, Germany
In order to identify genes that are differentially expressed as a consequence of stress due to paraquat, we used the differential display technique (1) to compare mRNA expression patterns in Caenorhabditis elegans. A C. elegans mixed-stage worm population, as well as a homogeneous larval population were treated with 100 mM paraquat, parallel to controls. Over 50 mRNA species that are potentially up-regulated in response to paraquat were identified. Sixteen of these candidates were re-amplified, ligated into plasmid vectors and the nucleotide sequences were determined. The induction of four of these expressed sequence tags (ESTs) designated L1, M47, M96 and M132 were confirmed in two independent stress / differential display experiments, as well as by northern blot analysis with RNA from stressed and unstressed worms. The nucleotide sequences of the independently isolated L1 and M47 ESTs were found to be identical. Their corresponding mRNA level increased more than 40-fold in the larval stage, and to a lesser extent in the mixed-stage worm population, in response to paraquat. Induction levels of 3 - 5 fold were observed for the M132 and M96 ESTs, in both larval and mixed populations. All of the isolated ESTs showed homology to portions of the C. elegans cosmids. The L1/M47 EST is derived from a gene encoding one of the putative C. elegans glutathione S-transferases. The paraquat-inducible M132 EST was also identified, and encodes a putative C2H2 - type zinc finger protein, possessing an N-terminal leucine zipper. However, the M96 EST appears to be a novel gene whose product has not yet been identified. Searches of other eukaryotic nucleotide sequence databases did not reveal any significant homologies to known sequences from any organism. Since paraquat is known to generate superoxide radicals in vivo, and the cellular superoxide dismutase (SOD) enzyme complex is responsible for the quenching of the deleterious effects of these radicals, the response of the C. elegans superoxide dismutases (2,3,4) to paraquat was also investigated in this study. Northern blot experiments demonstrated that mRNA steady state levels of the C. elegans manganese type and the copper/zinc type superoxide dismutases increased two-fold in response to paraquat, in the larval population. In contrast, mixed-stage populations did not show any apparent increase in the levels of these SOD mRNAs in response to paraquat. References: 1. Liang, P., Pardee, A.B. (1992). Science 257: 967 - 971 2. Giglio, M-P., Hunter, T., Bannister, J.V., Bannister, W.H., Hunter, G.J. (1994). Biochem. Mol. Biol. Int. 33 (1): 37-40 3. Giglio, A. M., Hunter, T., Bannister, J.V., Bannister, W.H., Hunter, G.J. (1994) . Biochem. Mol. Biol. Int. 33 (1): 37-40 4. Larsen, P.L. (1993). Proc. Natl. Acad. Sci. USA, 90: 8905-8909