Ten to fifteen minutes following death, a large release of CO2 is produced in many species when killed by high temperature. Studied in mosquitoes, hissing cockroaches, grasshoppers, and desert harvester ants, this post-mortal peak (PMP) appears to be temperature-dependent and, to our knowledge, does not occur in insects killed by means other than high temperature. Four effects were applied to common house crickets (Acheta domestica) to analyze the origin and properties of the PMP. First, it was shown that the PMP does not occur without oxygen. Second, post-mortal CO2 release was studied as a function of temperature-exposure following death and it was established that the phenomenon is dependent on extreme temperatures and runs to completion when exposed to temperatures above 60°C. Third, basic and buffered solutions were employed to assess the possible involvement of dissolved HCO3- (bicarbonate), the dissolved form of CO2, in production of the peak. Hemolymph factors like bicarbonate did not appear to have an effect on the PMP. Finally, exposure to hydrogen cyanide inhibited the PMP, demonstrating the involvement of mitochondria and cytochrome c oxidase in particular. Together, these results rule out any effect of hemolymph or possible CO2 stores in the body of an insect on the PMP. The PMP occurs as an aerobic mitochondrial reaction that requires high initiation temperatures. We believe that this underlying cause may be mitochondrial breakdown at high-temperatures. More specifically, fluidity of the mitochondrial membranes likely increases with high heat, disabling the established proton gradient and ATP production. The resultant accumulation of electron carriers allows for cyclic, but futile operation of the citric acid cycle and electron transport chain with remaining pyruvate stores.
A prolific writer, a much sought-after speaker, and a highly respected professor, Richard Beidleman is one of Colorado College's most notable faculty members. He taught zoology from 1957-1968 and biology from 1968-1988. His research interests centered on the role of natural scientists in frontier America and Australia, and he helped author high school and junior high school biology textbooks, among approximately 250 other published works. The Colorado Springs community knows him best as a dedicated environmental activist who fought for many years for such causes as the preservation of the White House Ranch and the Garden of the Gods Park, the prevention of strip mining along Front Range quarries, and the successful League of Women Voters lawsuit against the City of Colorado Springs regarding the Palmer deeded parks. He served on the Colorado State Parks Board for eight years, including three and a half years as its chairman and succeeded, among other things, in obtaining Muehler Ranch as a state park. The Beidleman Environmental Center at Sondermann Park was established in his honor by the City of Colorado Springs.
Dr. Mary Alice âPinkyâ Hamilton first came to Colorado Springs in 1947 with her sister, Sally, and brother-in-law, Robert M. Stabler, as he joined the Colorado College faculty as a zoologist. A 1933 graduate of Elmira College, New York, Hamilton received her Ph.D. in physiology from Columbia University and from 1939 to 1941 did research at the University of Michigan Medical School. Hamilton became the associate lab director for the Colorado Foundation for Research in Tuberculosis from 1947 to 1952. She began to lecture in zoology at Colorado College in 1950, becoming assistant professor in 1958, associate professor in 1963, professor of biology in 1972, and retiring as professor emerita in 1977. She also assisted her brother-in-law, Robert Stabler, with research projects related to trichomoniasis in pigeons and falcons.
Professor C. William T. Penland received his B.A. in 1920 from the University of Wyoming and his Ph.D. in Biology in 1925 from Harvard University. Except for a period of military service during World War II, and a semester in South America, he taught at Colorado College continuously from 1922 until his retirement in 1968, serving on the faculty longer than anyone else in the institution's history. An avid mountaineer, Dr. Penland was particularly well-known for his studies of the fungi and algae of Alpine tundra. His interview includes descriptions of the low faculty salaries, the Biology Department and Forestry School, the appearance of campus and Colorado Springs, President Duniway's administration, and the Alpine Laboratories of the Carnegie Institution (located three miles up the Cog Railway.) He talks about his extracurricular activities: mountaineering, hiking with Saturday Knights, Round Table Club, and searching for new plants.
PAL-1 is a protein that regulates posterior development of Caenorhabditis elegans embryos. Although pal-1 mRNA is present throughout the entire embryo, the PAL-1 protein is only transcribed in the posterior end of the nematode worm. MEX-3, a RNA binding protein, binds to the pal-1 mRNA, preventing its translation in the anterior section of the embryo. The MEX-3 protein is essential to maintaining embryo polarity and ensuring that posterior features develop only in the posterior end of the worm. During development, MEX-3 is present throughout the 1-cell and 2-cell embryo stage. MEX-3 is then degraded in the posterior end during the 4-cell stage, allowing the expression of PAL-1 in the two posterior blastomeres. By the 8-cell stage, MEX-3 is depleted from the entire embryo with remnants remaining in germline cells. The ubiquitination pathway is hypothesized to mark MEX-3 for degradation, localizing the protein at various stages of embryo development. This study screened various E3 ubiquitin ligases to determine which ligases are specifically used to mark MEX-3 for degradation during embryo development. Double-stranded RNA was created for selected E3 ubiquitin ligases and then injected into adult worms. This invoked RNA interference (RNAi) of these ubiquitin ligases in the embryos of the adult worms. Knockout of genes D2089.2, F46A9.5, F59B2.6, and Y82E9BR.15 resulted in embryonic lethality. Fluorescence microscopy of GFP::MEX-3 (green fluorescent protein labeled MEX-3) revealed that only F59B2.6 (zif-1 gene) and Y82E9BR.15 (elc-1 gene) knockouts affected MEX-3 localization. Double knockouts of zif-1 and another developmental gene, mex-5, support the hypothesis that zif-1 acts after other regulatory events in MEX-3 localization.