Collagen type IV of Drosophila is stockpiled in the growing oocyte and differentially located during early stages of embryogenesis

We have developed and characterized a battery of specific polyclonal antibodies directed against specific portions of the α-chain of collagen type IV synthesized in Drosophila by the gene DCg1. Here, we describe the use of these antibodies together with in situ hybridization experiments in an attempt to study the expression and localization of collagen type IV during Drosophila oogenesis and early embryogenesis. The results clearly demonstrate that DCg1 is maternally expressed by follicle cells and that the collagen type IV chain produced is stockpiled in the growing oocyte. During the gastrulation stages, this component of Drosophila basement membranes concentrated on cells involved in the gradual invaginations leading to morphogenetic furrows. The presence of collagen type IV, which is an RGD-bearing molecule, during early stages of Drosophila development is discussed in comparison with the crucial, active role its vertebrate counterpart is supposed to play in morphogenetic processes.