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Localization and partial characterization of some extracellular matrix molecules which may be involved in gut morphogenesis of the starfish, Pisaster ochraceus

University of British Columbia

The extracellular matrix (ECM) is important in normal development by influencing cell adhesion, migration, and differentiation. If one includes the oocyte jelly coat as a part of the ECM, it is present from before fertilization. ECM is made up of a variety of molecules, many of which are uncharacterized in lower invertebrates. In this study, a polyclonal antibody (PJC-1) which recognizes several high molecular weight ECM molecules of the starfish Pisaster ochraceus was used in conjunction with a variety of techniques to study the ECM. Using immunofluorescence light microscopy and immunogold transmission electron microscopy, it was determined that PJC-1 recognizes molecules found in the acrosomal granule and in the external mucous ECM of sperm, and in the jelly coat, vitelline membrane, cortical granules, yolk granules, cell membrane and cytoplasm of mature oocytes. In embryo stages before, during, and after gastrulation, molecules recognized by PJC-1 are found in vesicles in ectodermal, mesenchymal, and endodermal cells. These molecules were more highly expressed in the hyaline layer, blastocoel ECM, and in particular the ECM of the gut lumen as development progressed. Immunoblots of extracts from different developmental stages showed that an increase of a 160 kDa (non-reduced) molecule correlated with the onset of gastrulation, while the upregulation of a second molecule of about 145 kDa (reduced) coincided with segmentation and differentiation of the larval gut. Embryos raised in sea water containing PJC-1 at 2.5%, 5%, and 10% exhibited perturbation of the formation of the distal gut, indicated by the development of a prolapsed anus. When viewed together, the perturbation, immunoblot, immunogold and immunofluorescence data suggest that PJC-1 recognizes at least one molecule which may be involved in the morphogenesis of the digestive tract.

Thesis/Dissertation

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2009-06-11

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http://hdl.handle.net/2429/8981

Anatomy, Cell Biology and Physiology

University of British Columbia

UBCV

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