CELL AUTONOMOUS EXPRESSION OF PERLECAN AND PLASTICITY OF CELL-SHAPE IN EMBRYONIC MUSCLE OF CAENORHABDITIS-ELEGANS

Perlecan, a component of the extracellular matrix (ECM), is essential for myofilament formation and muscle attachment in Caenorhabditis eleg ans. We show here that perlecan is a product of muscle and that it beh aves in a cell autonomous fashion. That is, perlecan expressed in an i ndividual muscle cell does not spread beyond the borders of the ECM un derlying that cell. Using a polyclonal antibody that recognizes all is oforms of perlecan, we demonstrate that this protein first appears ext racellularly at the comma stage (approx. 350 min) of development. We a lso show that during morphogenesis muscle cells have a heretofore unde scribed plasticity of shape. This ability to regulate cell shape allow s cells within a muscle quadrant to compensate for missing cells and t o form a functional quadrant. A dramatic example of this morphological flexibility can be observed in animals in which the D blastomere has been removed by laser ablation. Such animals, lacking 20 of the 81 emb ryonic body wall muscle cells, can survive to become viable adult anim als indistinguishable from wildtype animals. This demonstrates that th e assembly of an embryo via a stereotypic lineage does not preclude a more general regulation during morphogenesis. It appears that embryos are flexible enough to immediately compensate for drastic alterations in tissue composition, a feature of development that may be of general importance during evolution. (C) 1996 Academic Press, Inc.