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Portland State University

Biology Faculty Publications and Presentations

2010

Articles 1 - 8 of 8

Full-Text Articles in Life Sciences

Hearing Loss In Stranded Odontocete Dolphins And Whales, David Mann, Mandy Hill-Cook, Charles Manire, Danielle Greenhow, Eric Montie, Jessica Powell, Randall Wells, Gordon Bauer, Petra Cunningham-Smith, Robert Lingenfelser, Robert Digiovanni, Abigale Stone, Micah Brodsky, Robert Stevens, George Kieffer, Paul Hoetjes Nov 2010

Hearing Loss In Stranded Odontocete Dolphins And Whales, David Mann, Mandy Hill-Cook, Charles Manire, Danielle Greenhow, Eric Montie, Jessica Powell, Randall Wells, Gordon Bauer, Petra Cunningham-Smith, Robert Lingenfelser, Robert Digiovanni, Abigale Stone, Micah Brodsky, Robert Stevens, George Kieffer, Paul Hoetjes

Biology Faculty Publications and Presentations

The causes of dolphin and whale stranding can often be difficult to determine. Because toothed whales rely on echolocation for orientation and feeding, hearing deficits could lead to stranding. We report on the results of auditory evoked potential measurements from eight species of odontocete cetaceans that were found stranded or severely entangled in fishing gear during the period 2004 through 2009. Approximately 57% of the bottlenose dolphins and 36% of the rough-toothed dolphins had significant hearing deficits with a reduction in sensitivity equivalent to severe (70-90 dB) or profound (>90 dB) hearing loss in humans. The only stranded short-finned …


Virus Silicification Under Simulated Hot Spring Conditions, James R. Laidler, Kenneth M. Stedman Aug 2010

Virus Silicification Under Simulated Hot Spring Conditions, James R. Laidler, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Silicification of organisms in silica-depositing environments can impact both their ecology and their presence in the fossil record. Although microbes have been silicified under laboratory and environmental conditions, viruses have not. Bacteriophage T4 was successfully silicified under laboratory conditions that closely simulated those found in silica-depositing hot springs. Virus morphology was maintained, and a clear elemental signature of phosphorus was detected by energy-dispersive X-ray spectrophotometry (EDS).


Pcif1 Modulates Pdx1 Protein Stability And Pancreatic Β Cell Function And Survival In Mice, Kathryn C. Claiborn, Mira M. Sachdeva, Corey E. Cannon, David N. Groff, Jeffrey D. Singer, Doris A. Stoffers Jul 2010

Pcif1 Modulates Pdx1 Protein Stability And Pancreatic Β Cell Function And Survival In Mice, Kathryn C. Claiborn, Mira M. Sachdeva, Corey E. Cannon, David N. Groff, Jeffrey D. Singer, Doris A. Stoffers

Biology Faculty Publications and Presentations

The homeodomain transcription factor pancreatic duodenal homeobox 1 (Pdx1) is a major mediator of insulin transcription and a key regulator of the β cell phenotype. Heterozygous mutations in PDX1 are associated with the development of diabetes in humans. Understanding how Pdx1 expression levels are controlled is therefore of intense interest in the study and treatment of diabetes. Pdx1 C terminus–interacting factor-1 (Pcif1, also known as SPOP) is a nuclear protein that inhibits Pdx1 transactivation. Here, we show that Pcif1 targets Pdx1 for ubiquitination and proteasomal degradation. Silencing of Pcif1 increased Pdx1 protein levels in cultured mouse β cells, and Pcif1 …


Metagenomes From High-Temperature Chemotrophic Systems Reveal Geochemical Controls On Microbial Community Structure And Function, William P. Inskeep, Douglas B. Rusch, Zackary J. Jay, Markus J. Herrgard, Mark A. Kozubal, Toby H. Richardson, Richard E. Macur, Natsuko Hamamura, Ryan Dem. Jennings, Bruce W. Fouke, Anna-Louise Reysenbach, Frank Roberto, Mark Young, Ariel Schwartz, Eric S. Boyd, Jonathan H. Badger, Eric J. Mathur, Alice C. Ortmann, Mary Bateson, Gill Geesey Mar 2010

Metagenomes From High-Temperature Chemotrophic Systems Reveal Geochemical Controls On Microbial Community Structure And Function, William P. Inskeep, Douglas B. Rusch, Zackary J. Jay, Markus J. Herrgard, Mark A. Kozubal, Toby H. Richardson, Richard E. Macur, Natsuko Hamamura, Ryan Dem. Jennings, Bruce W. Fouke, Anna-Louise Reysenbach, Frank Roberto, Mark Young, Ariel Schwartz, Eric S. Boyd, Jonathan H. Badger, Eric J. Mathur, Alice C. Ortmann, Mary Bateson, Gill Geesey

Biology Faculty Publications and Presentations

The Yellowstone caldera contains the most numerous and diverse geothermal systems on Earth, yielding an extensive array of unique high-temperature environments that host a variety of deeply-rooted and understudied Archaea, Bacteria and Eukarya. The combination of extreme temperature and chemical conditions encountered in geothermal environments often results in considerably less microbial diversity than other terrestrial habitats and offers a tremendous opportunity for studying the structure and function of indigenous microbial communities and for establishing linkages between putative metabolisms and element cycling. Metagenome sequence (14-15,000 Sanger reads per site) was obtained for five hightemperature (>65°C) chemotrophic microbial communities sampled from …


Selection Ratios On Community Aggregated Traits To Estimate Ecological Filters Imposed On Species By Sites, Nathanael I. Lichti, Michael T. Murphy Feb 2010

Selection Ratios On Community Aggregated Traits To Estimate Ecological Filters Imposed On Species By Sites, Nathanael I. Lichti, Michael T. Murphy

Biology Faculty Publications and Presentations

Variation in community structure is mediated by interactions between species traits and a site's environmental characteristics. Previously, data on community composition at sites has been employed to correlate trait and environmental variables (e.g., RLQ analysis) and to predict community-level expression of quantitative traits (i.e., community aggregated traits). Here, we demonstrate that the selection ratio, a method originating in animal resource selection studies, can estimate the ecological filters that site conditions impose on species traits by combining observed community aggregated traits with null models of species availability. This flexible, nonparametric approach expresses the filter at each site as a probability density …


Thermocrinis Minervae Sp. Nov., A Hydrogen And Sulfur-Oxidizing, Thermophilic Member Of The Aquificales From A Costa Rican Terrestrial Hot Spring, Sara L. Caldwell, Yitai Liu, Isabel Ferrera, Terry Beveridge, Anna-Louise Reysenbach Jan 2010

Thermocrinis Minervae Sp. Nov., A Hydrogen And Sulfur-Oxidizing, Thermophilic Member Of The Aquificales From A Costa Rican Terrestrial Hot Spring, Sara L. Caldwell, Yitai Liu, Isabel Ferrera, Terry Beveridge, Anna-Louise Reysenbach

Biology Faculty Publications and Presentations

A thermophilic bacterium, designated strain CR11T , was isolated from a filamentous sample collected from a terrestrial hot spring on the south-western foothills of the Rincón volcano in Costa Rica. The Gram-negative cells are approximately 2.4–3.9 mm long and 0.5–0.6 mm wide and are motile rods with polar flagella. Strain CR11T grows between 65 and 85 6C (optimum 75 6C, doubling time 4.5 h) and between pH 4.8 and 7.8 (optimum pH 5.9–6.5). The isolate grows chemolithotrophically with S0 , S2O2{ 3 or H2 as the electron donor and with O2 (up to 16 %, v/v) as the sole electron …


The Isolation Of Viruses Infecting Archaea, Kenneth M. Stedman, Kate Porter, Mike L. Dyall-Smith Jan 2010

The Isolation Of Viruses Infecting Archaea, Kenneth M. Stedman, Kate Porter, Mike L. Dyall-Smith

Biology Faculty Publications and Presentations

A mere 50 viruses of Archaea have been reported to date; these have been investigated mostly by adapting methods used to isolate bacteriophages to the unique growth conditions of their archaeal hosts. The most numerous are viruses of thermophilic Archaea. These viruses have been discovered by screening enrichment cultures and novel isolates from environmental samples for their ability to form halos of growth inhibition, or by using electron microscopy to screen enrichment cultures for virus-like particles. Direct isolation without enrichment has not yet been successful for viruses of extreme thermophiles. On the other hand, most viruses of extreme halophiles, the …


Mitochondrial Physiology Of Diapausing And Developing Embryos Of The Annual Killifish Austrofundulus Limnaeus: Implications For Extreme Anoxia Tolerance, Jeffrey M. Duerr, Jason E. Podrabsky Jan 2010

Mitochondrial Physiology Of Diapausing And Developing Embryos Of The Annual Killifish Austrofundulus Limnaeus: Implications For Extreme Anoxia Tolerance, Jeffrey M. Duerr, Jason E. Podrabsky

Biology Faculty Publications and Presentations

Diapausing embryos of the annual killifish Austrofundulus limnaeus have the highest reported anoxia tolerance of any vertebrate and previous studies indicate modified mitochondrial physiology likely supports anoxic metabolism. Functional mitochondria isolated from diapausing and developing embryos of the annual killifish exhibited VO2, respiratory control ratios (RCR), and P:O ratios consistent with those obtained from other ectothermic vertebrate species. Reduced oxygen consumption associated with dormancy in whole animal respiration rates are correlated with maximal respiration rates of mitochondria isolated from diapausing versus developing embryos. P:O ratios for developing embryos were similar to those obtained from adult liver, but were diminished in …