(full paper is archived in the Miller Library)
Title: Ubiquitin-conjugate levels show variation and
occasional clearing in Anthopleura elegantissima in the
Student Author(s): Hong, Deborah W.
Faculty Advisor(s): Somero, George
Location: Final papers biology 175H
Date: June 2005
Abstract: The ubiquitin-proteasome proteolytic pathway is a specific and tightly regulated means by which intracellular proteins, including proteins involved in cell cycle regulation, transcriptional activators, and cell surface receptors, are degraded. Proteins may be degraded because they are no longer needed or because they are mutated, denatured, or misfolded. Each protein substrate is covalently tagged by several 76-amino acid ubiquitin molecules; the tagged protein is degraded by the 26S proteasome complex, releasing free ubiquitin. Deubiquitinating enzymes regulate the generation and recycling of ubiquitin levels in the cell. This field study examined trends in ubiquitin-conjugate levels in Anthopleura elegantissima in order to determine whether overall changes in ubiquitin-conjugate levels are detectable and significant and also to observe the timescale of any such cycles of conjugate build-up and clearing. Levels of ubiquitin-conjugates in the field in A. elegantissima were examined every four hours over a four day period at two sites by Western blots and dot blots using an anti-ubiquitin-conjugate antibody (Lars Tomanek, Somero Lab). Mean pooled intensities of dot blot wells revealed occasional clearing of ubiquitin conjugates over the collection period with no difference between the two sites, suggesting that at some time points, all detectable ubiquitin must be in its free form or itself been degraded. Time series analysis revealed no significant predictive factors that correlated to ubiquitin-conjugate levels. Factors examined were exposure to sun, presence of rain, immersion/emersion conditions prior to and at the time of sampling, extrapolated tidal height, time of day, and anemone body temperature.