Date of Graduation

Spring 2008

Degree

Master of Science in Cell and Molecular Biology

Department

Biomedical Sciences

Committee Chair

Colette Witkowski

Abstract

C. elegans is a good model organism that has the potentiality for in vivo experimentations. It is able to reveal molecules that regulate embryonic development such as type IV collagen, a component of basement membranes and actin filament. Type IV collagen is initially expressed in body wall muscle cell. It provides elasticity and contraction to embryonic muscle cells and sustains epidermal cell shape in embryogenesis. The mutations of type IV collagen have been characterized to cause embryonic lethality with disruption of the myofilament lattice. Moreover, actins have been shown to play important roles in early embryogenesis especially in cytokinesis, cell proliferation, and animal elongation. During early morphogenesis, body wall muscle cells are essential to induce embryonic contraction and to promote development. Muscle cell structure and function are initially established by perlecan, the basement membrane component. As the morphogenesis progresses, collagen IV has been shown to be crucial to further maintain embryonic elongation and movement. Loss of type IV collagen causes detachment of body wall muscle cells. Preliminary experiments have further shown that the detachment of muscle cells is induced by the disruption of actin filament assembly. These experiments were conducted to illustrate interdependency between type IV collagen and actin filament in the body wall muscle cell organization. C. elegans strain with emb-9 mutation was selected for the investigation. To evaluate collagen IV function and its role in actin filament organization, wild type and mutant embryos were harvested and immunostained to distinguish the cellular distribution and expression of actin filaments and collagen IV. Wild type embryos exhibited normal expression of type IV collagen and actin filament deposition in body wall muscle cells. Whereas the mutant embryos lacking collagen IV showed disruption of collagen IV and actin filament resulting in body wall muscle cell disassembly. This evidence supports that collagen IV is essential in actin filament function in animal embryogenesis.

Keywords

basement membranes, body wall muscle, collagen IV, actin filament, immunostaining

Subject Categories

Medical Molecular Biology

Copyright

© Hinda Doucoure

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