viking: identification and characterization of a second type IV collagen in Drosophila

We have taken an enhancer trap approach to identify genes that are expressed in hematopoietic cells and tissues of Drosophila. We conducted a molecular analysis of two P-element insertion strains that have reporter gene expression in embryonic hemocytes, strain 197 and viking(ICO). This analysis has determined that viking encodes a collagen type IV gene, alpha 2(IV). The viking locus is located adjacent to the previously described DCg1, which encodes collagen alpha 1(IV), and in the opposite orientation. The alpha 2(IV) and alpha 1(IV) collagens are structurally very similar to one another, and to vertebrate type TV collagens. In early development, viking and DCg1 are transcribed in the same tissue-specific pattern, primarily in the hemocytes and fat body cells. Our results suggest that both the alpha 1 and alpha 2 collagen IV chains may contribute to basement membranes in Drosophila. This work also provides the foundation for a more complete genetic dissection of collagen type IV molecules and their developmental function in Drosophila. (C) 1997 Elsevier Science B.V.