My research interests are focused on mechanisms of internal defense against disease and developmental processes in marine organisms, with particular emphasis on protein- carbohydrate interactions. The current programs in my laboratory include the molecular aspects and evolution of acute phase response factors in both invertebrates such as oysters, crabs and sea squirts, and cold-blooded vertebrates such as finfish. Our continued research studies on the molecular recognition mechanisms in marine invertebrates have resulted in the isolation of a number of C-type lectins from the marine protochordate Clavelina picta, commonly known as "clear sea squirt". From the functional point of view, one of the most intriguing aspects of these molecules resides on the fact that they interact with bacterial strains from the environment and with sulfated galactans that constitute the tunic. The novel hypothesis we have developed points to these mosaic molecules as opsonins in the recognition and processing of microbial pathogens, but also as active in wound repair mechanisms. We have identified one of the lectins as a precursor of the mannose-binding proteins from vertebrates. In man, these opsonins can activate complement upon binding to the pathogenic bacteria and defective point mutations in their structure are responsible for immunodeficiencies in early childhood. We are currently characterizing equivalent proteins from tissues and plasma of the stripped bass Morone saxatilis. Within the research program on sugar-binding proteins that are involved in cell-cell and cell-intercellular matrix minteractions, recent developments accomplished in my laboratory include the isolation, biochemical characterization and crystallization of S-type lectins from several vertebrates and invertebrates. In collaboration with scientists at CARB and Johns Hopkins University we have conducted studies that have resulted in the resolution of their three-dimensional structures and the characterization of the thermodynamic aspects of protein-sugar interactions. These studies are aimed at the elucidation of structure/function relationships that will provide insight on the biological roles of lectins in internal defense and developmental processes.

Another major initiative in my laboratory is a comprehensive research program on Perkinsus marinus ("Dermo"), a protozoan parasite that has devastated the eastern oyster industry in the East coast of USA, including the Chesapeake Bay area. The development and optimization of in vitro continuous cultures of the parasite P. marinus in my laboratory has provided not only the first reliable and abundant source of parasites for developing molecular probes for diagnostic purposes, but also a unique opportunity to obtain a clear understanding of the organism's physiology, in particular the factors that promote Its virulence and regulate its stage differentiations. Recent accomplishments in our research program on "Dermo" disease includes (a) The development of a PCR-based DNA amplification method for the rapid, sensitive and specific diagnosis of the disease and its use for the characterization of the genetic variability of the parasite and assessing its presence in putative inten-nediate hosts, vectors and reservoir species; (b) Characterization of mechanisms for the parasite intracellular survival and cell cycle regulation in the host environment mediated by P. marinus superoxide dismutase, glycosidases and protein phosphatase; and finally, (c) Identification of defense mechanisms from refractory bivalve species that in the long term may allow the development of genetically engineered resistant C. virginica strains.