Identification of promoter elements of parasite nematode genes in transgenic Caenorhabditis elegans

Transformation of the free-living nematode Caenorhabditis elegans with prom oter/reporter gene constructs is a very powerful technique to examine and d issect gene regulatory mechanisms. No such transformation system is availab le for parasitic nematode species. We have exploited C. elegans as a hetero logous transformation system to examine activity and specificity of parasit ic nematode gene promoters. Using three different parasite promoter/lac Z r eporter constructs strict tissue-specific expression is observed. Upstream sequences of the Haemonchus contortus gut pepsinogen gene pep-1 and cystein e protease gene AC-2 direct expression exclusively in gut cells, while prom oter sequence of the Ostertagia circumcincta cuticular collagen gene colost -1 directs hypodermal-specific expression. Mutation analysis indicates that AC-2 promoter function is dependent on a GATA-like motif close to the tran slation start site, similar to our findings with the C. elegans cpr-1 cyste ine protease gene. While the spatial expression of these parasite promoters in C. elegans correlates with their expression in the parasite, the exact timing of expression does not. This suggests that regulatory mechanisms inf luencing the timing of expression may have evolved more rapidly than those controlling spatial expression of structural genes. (C) 1999 Elsevier Scien ce B.V. All rights reserved.