Yun Liu


This poster reflects research conducted as part of a course project designed to give students experience in the research process.



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Sea squirts belong to a class of organisms called Ascidians, which are sessile marine invertebrates found throughout the world attached to rocks, shells, pilings, and ships hulls. These organisms manufacture a series of compounds known as tunichromes, which have been implicated in the formation of the tough, tunic-like body covering. Ascidians are known for their bioaccumulation of metals, particularly vanadium and iron. These tunichromes contain polyphenolic polypeptides that are potent metal-complexing agents, which are found in the blood cells which circulate throughout the organism to assist in the maintenance and wound repair of the tunic. These polypeptides are contained within specialized blood cells and are released at the wound site. Iron+3 is sequestered in specialized cells containing tunichromes, which are involved in the synthesis of the tunic (a tough, leathery polymeric material). These tunichromes contain a novel amino acid: 3,4-dihydroxyphenyl-L-alanine (L-dopa) at up to 39% by weight. Involvement of the sequestered iron atoms in the tunic are thought to participate in the cross-linking mechanism, resulting in the formation of the structural material that comprises the tunic-like body wall of this sessile invertebrate. It is this capability to bind and sequester Fe+3 that makes tunichromes attractive as possible corrosion inhibitors on steel surfaces. This current research effort focuses on the isolation and purification of the tunichromes from two tunicates: Molgula manhattensis and Styela plicata. Through the use of standard and modified biochemical isolation and purification techniques and strategies, the tunichromes have been isolated and purified by high performance liquid chromatography (HPLC) on a reverese phase (RP) C-8 HPLC column using a water-acetonitrile gradient. The isolation and purification of one of the tunichromes isolated from S. plicata will be presented and discussed.

Publication Date


Project Designation

Course Project

Primary Advisor

Douglas C. Hansen

Primary Advisor's Department

Materials Degradation and Electrochemical Engineering (Research Institute-Materials Engineering)


Stander Symposium project

Research exercise: The Isolation and Purification of a Structural Polypeptide from the Ascidian Tunicate Styela plicata