Secretion of a novel class of iFABPs in nematodes: coordinate use of the Ascaris/Caenorhabditis model systems

A novel fatty acid binding protein, As-p18 is secreted into both the perivi telline and perienteric fluids of the parasitic nematode, Ascaris suum, and at least eight potential homologues of As-p18 have been identified in the Caenorhabditis elegans genome. The products of the three most closely relat ed homologues are fatty acid binding proteins (LBP-1, LBP-2 and LBP-3) whic h contain putative secretory signals. Phylogenetic analysis revealed that t hese secreted fatty acid binding proteins comprise a distinct gene class wi thin the fatty acid binding protein family and are possibly unique to nemat odes. To examine the potential sites of As-p18 secretion, the expression of the putative promoters of the C. elegans homologues was examined with GFP reporter constructs. The developmental expression of lbp-1 was identical to that of As-p18 and consistent with the secretion of LBP-1 from the hypoder mis to the perivitelline fluid. The expression patterns of lbp-2 and lbp-3 were consistent with the secretion of LBP-2 and LBP-3 from muscle into the perienteric fluid later in development. These studies demonstrate that at l east some perivitelline fluid proteins appear to be secreted from the hypod ermis prior to the formation of the cuticle and, perhaps more importantly, that this coordinate C. elegans/A. storm approach may be potentially useful for examining a number of key physiological processes in parasitic nematod es. (C) 2000 Elsevier Science B.V. All rights reserved.