Jason Wolfe
 Professor
Ph.D. (zoology) University of California, Berkeley
Campus Extension: 3239
Room #: Hall-Atwater Labs 154
E-Mail: JWOLFE@WESLEYAN.EDU
Cell reproduction; Cell interactions; Cell death.
We have been asking questions about cell recognition and adhesion, as well as cell differentiation and morphogenesis, by studying sexual interaction in the single-celled organism, Tetrahymena thermophila. In recent years, we have begun to also exploit a novel developmental property of this cell-type to also study the regulation of nuclear death as it relates to the process of apoptosis.
Apoptosis, or programmed cell death, is accompanied by a condensation of the cell and its fragmentation into pieces. One of the characteristic features of apoptosis is the condensation of nuclear chromatin and the irreversible degradation of nuclear DNA. It is likely that the destruction of the genome, which leads inevitably to cell death, is the key process in the regulation of cell death. Therefore, it is important to understand the biochemical mechanism for nuclear death, and the relationship between chromatin condensation and the enzymatic cleavage of DNA strands.
To address these issues, and to explore the question of the genetic regulation of nuclear death, we are making use of the Tetrahymena system where nuclear death occurs as part of the normal developmental cycle of nuclear differentiation during conjunction. The novel aspect of this research is that it allows us to study nuclear death in a living cell. Because the cell is living, we can ask more focused questions that might not be possible in a situation where the cell is no longer a viable entity.
We have begun to ask questions about changes in gene expression and biochemical processed occurring during nuclear death. Gel electrophoresis and immunoflourescence are being used to study the pattern and timing of fragmentation of DNA, and the identity of enzymes involved in the process. Electron microscopy is being used to study the morphology of the disintegrating nucleus. Mutants that are blocked in nuclear disintegration are being used for comparative processes. Additionally, the differences in gene expression between cells undergoing nuclear disintegration and those pharmacologically or genetically blocked, are being examined using PCR technology.
Our laboratory has also developed a
fluorescence protocol for differential staining nuclei in the process of dying even while the cells are still alive. This stain, which we call a vital apofluor, offers the potential not only for identifying living apoptotic cells, but also for separating them from a population of otherwise "normal" cells.
The ciliated protozoan is an interesting model system for exploring issues of cell reproduction and development in higher organisms. This system also has the potential to answer important questions about the regulation of cell death that may not be possible to answer in cells that are actually dying.
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