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Virginia Weis
Professor, Zoology
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RESEARCH:
We are investigating the cellular and molecular interactions underlying mutualistic symbioses between cnidarians, such as corals and anemones, and their photosynthetic dinoflagellate symbionts. We are interested in the establishment, maintenance and breakdown of these associations, that form the trophic and structural foundation of the coral reef ecosystem. We use several model associations in our studies, including a Hawaiian stony coral, Fungia scutaria, a tropical sea anemone Aiptasia pallida, a temperate sea anemone found on the Oregon coast, Anthopleura elegantissima, and a Red Sea soft coral, Heteroxenia fuscescens.
We are examining the dynamic process of the onset of symbiosis during the host cnidarian larval stage. Most species must acquire symbionts anew with each generation and therefore must engage in a complex recognition and specificity process that results in the establishment of a stable symbiosis. We are using confocal microscopy and in situ hybridizations to examine the dynamics of first infection, such as the location and mechanism of algal uptake by host larvae. In addition we are examining changes in gene expression of host larvae that occurs during symbiosis onset.
We are interested in identifying genes that are upregulated specifically as a function of the symbiotic state in host cnidarians. We are employing a variety of techniques, including degenerate primer RT-PCR, subtractive libraries and RNAi, to identify and characterize host “symbiosis” genes. We are most interested in their function in the association. To date we have identified several host symbiosis genes using these approaches. Recently we have begun investigating the breakdown of the symbiosis and the role of apoptosis in this process. Coral bleaching, or the loss of host animal pigment, is caused by the breakdown of the host animal/algal symbiont association. Bleaching is a growing global environmental problem and can cause the destruction of the entire reef ecosystems. My lab is investigating links between coral bleaching and apoptosis. As a first step we are characterizing apoptosis genes and apoptotic pathways in host animals, one of the first investigations of these critical cellular mechanisms to be performed on lower metazoans, To date we have identified a caspase sequence and are in the process of searching for an apaf-1 homolog using a yeast two-hybrid system.