Life Sciences Commons^™

Taxis Toward Hydrogen Gas By Methanococcus Maripaludis, Kristen A. Brileya, James M. Connolly, Carey Downey, Robin Gerlach, Matthew W. Fields

Biology Faculty Publications and Presentations

Knowledge of taxis (directed swimming) in the Archaea is currently expanding through identification of novel receptors, effectors, and proteins involved in signal transduction to the flagellar motor. Although the ability for biological cells to sense and swim toward hydrogen gas has been hypothesized for many years, this capacity has yet to be observed and demonstrated. Here we show that the average swimming velocity increases in the direction of a source of hydrogen gas for the methanogen, Methanococcus maripaludis using a capillary assay with anoxic gas-phase control and time-lapse microscopy. The results indicate that a methanogen couples motility to hydrogen concentration …

Effect Of Mycorrhizal Colonization And Light Limitation On Growth And Reproduction Of Lima Bean (Phaseolus Lunatus L.), Daniel J. Ballhorn, Jess A. Millar

Biology Faculty Publications and Presentations

Plants can respond with sink stimulation of photosynthesis when colonized with fungal or bacterial root symbionts, compensating costs of carbohydrate allocation to the microbes. However, constraints may arise under light limitation when plants cannot extensively increase photosynthesis. We hypothesize that under such conditions the costs for maintaining the symbiosis outweigh the benefits, ultimately turning the mutualist microbes into parasites, resulting in reduced plant growth and reproduction.

Using lima bean (Phaseolus lunatus) as experimental plant, we applied two levels of light (full light, 75% shading) and microbial inoculation (sterile soil, mycorrhizal fungi) and quantified both vegetative and generative plant …

Reversible Inactivation And Desiccation Tolerance Of Silicified Viruses, James R. Laidler, Jessica A. Shugart, Sherry L. Cady, Keith S. Bahjat, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Long-distance host-independent virus dispersal is poorly understood, especially for viruses found in isolated ecosystems. To
demonstrate a possible dispersal mechanism, we show that bacteriophage T4, archaeal virus Sulfolobus spindle-shaped virus Kamchatka, and vaccinia virus are reversibly inactivated by mineralization in silica under conditions similar to volcanic hot
springs. In contrast, bacteriophage PRD1 is not silicified. Moreover, silicification provides viruses with remarkable desiccation
resistance, which could allow extensive aerial dispersal.

Avoidance Of Apoptosis In Embryonic Cells Of The Annual Killifish Austrofundulus Limnaeus Exposed To Anoxia, Camie Lynn Meller, Jason E. Podrabsky

Biology Faculty Publications and Presentations

Embryos of the annual killifish Austrofundulus limnaeus have unequalled ability among vertebrates to survive long-term anoxia. Surprisingly, these embryos can survive for months in anoxia despite a large-scale decrease in ATP levels during the initial hours of anoxic exposure. These conditions are known to trigger apoptotic cell death in mammalian cells as a result of ischemia or anoxia. Anoxia-induced induction of apoptosis was investigated in four developmental stages of A. limnaeus that differ in their tolerance of anoxia, and thus may respond to anoxia uniquely. Exposure to staurosporine was used to determine if A. limnaeus cells were competent …

Cross-Species Array Comparative Genomic Hybridization Identifies Novel Oncogenic Events In Zebrafish And Human Embryonal Rhabdomyosarcoma, Eleanor Y. Chen, Kimberly P. Dobrinski, Kim H. Brown, Ryan Clagg, Elena Edelman, Myron S. Ignatius, Jin Yun Helen Chen, Jillian Brockmann, G. Petur Nielsen, Sridhar Ramaswamy, Charles Keller, Charles Lee, David M. Langenau

Biology Faculty Publications and Presentations

Human cancer genomes are highly complex, making it challenging to identify specific drivers of cancer growth, progression, and tumor maintenance. To bypass this obstacle, we have applied array comparative genomic hybridization (array CGH) to zebrafish embryonal rhabdomyosaroma (ERMS) and utilized cross-species comparison to rapidly identify genomic copy number aberrations and novel candidate oncogenes in human disease. Zebrafish ERMS contain small, focal regions of low-copy amplification. These same regions were commonly amplified in human disease. For example, 16 of 19 chromosomal gains identified in zebrafish ERMS also exhibited focal, low-copy gains in human disease. Genes found in amplified genomic regions were …

Residential Edges As Ecological Traps: Postfledgling Survival Of A Ground-Nesting Passerine In A Forested Urban Park, Amy A. Shipley, Michael T. Murphy, Adam H. Elzinga

Biology Faculty Publications and Presentations

Substantial offspring mortality can occur during the postfledging period of birds, but few postfledging survival studies have been conducted within the context of habitat suitability. We conducted a 2-year radiotelemetry study of Spotted Towhee (Pipilo maculatus) reproductive success and fledgling survival in a 24-ha forested park in a residential area of Lake Oswego, Oregon. In corroboration of previous research on this species, we found (1) that Spotted Towhees nested closer to the edge between the park and residential neighborhoods than expected by chance, and (2) that pairs nesting near edges produced the largest and most offspring. However, fates were reversed …

Evolution Of A Higher Intracellular Oxidizing Environment In Caenorhabditis Elegans Under Relaxed Selection, Joanna Joyner-Matos, Kiley A. Hicks, Dustin Cousins, Michelle Keller, Dee R. Denver, Charles F. Baer, Suzanne Estes

Biology Faculty Publications and Presentations

We explored the relationship between relaxed selection, oxidative stress, and spontaneous mutation in a set of mutationaccumulation (MA) lines of the nematode Caenorhabditis elegans and in their common ancestor. We measured steady-state levels of free radicals and oxidatively damaged guanosine nucleosides in the somatic tissues of five MA lines for which nuclear genome base substitution and GC-TA transversion frequencies are known. The two markers of oxidative stress are highly correlated and are elevated in the MA lines relative to the ancestor; point estimates of the per-generation rate of mutational decay (DM) of these measures of oxidative stress are similar to …

Insights Into Archaeal Evolution And Symbiosis From The Genomes Of A Nanoarchaeon And Its Inferred Crenarchaeal Host From Obsidian Pool, Yellowstone National Park, Mircea Podar, Kira S. Makarova, David E. Graham, Yuri L. Wolf, Eugene V. Koonin, Anna-Louise Reysenbach

Biology Faculty Publications and Presentations

Background: A single cultured marine organism, Nanoarchaeum equitans, represents the Nanoarchaeota branch of symbiotic Archaea, with a highly reduced genome and unusual features such as multiple split genes.

Results: The first terrestrial hyperthermophilic member of the Nanoarchaeota was collected from Obsidian Pool, a thermal feature in Yellowstone National Park, separated by single cell isolation, and sequenced together with its putative host, a Sulfolobales archaeon. Both the new Nanoarchaeota (Nst1) and N. equitans lack most biosynthetic capabilities, and phylogenetic analysis of ribosomal RNA and protein sequences indicates that the two form a deepbranching archaeal lineage. However, the Nst1 …

Migration Timing And Wintering Areas Of Three Species Of Flycatchers (Tyrannus) Breeding In The Great Plains Of North America, Alex E. Jahn, Victor R. Cueto, James W. Fox, Michael S. Husak, Daniel H. Kim, Diane V. Landoll, Jesús Pinto Ledezma, Heather K. Lepage, Douglas J. Levey, Michael T. Murphy, Rosalind B. Renfrew

Biology Faculty Publications and Presentations

Descriptions of intra- and interspecific variation in migratory patterns of closely related species are rare yet valuable because they can help assess how differences in ecology and life-history strategies drive the evolution of migration. We report data on timing and location of migration routes and wintering areas, and on migratory speed and phenology, of Eastern Kingbirds (Tyrannus tyrannus) from Nebraska and Oklahoma and of Western Kingbirds (T. verticalis) and Scissor-tailed Flycatchers (T. forficatus) from Oklahoma. Eastern Kingbirds primarily departed the breeding site in September, migrating to the Amazon Basin (Bolivia and Brazil), >6,400 km …

Sequencing And De Novo Transcriptome Assembly Of Brachypodium Sylvaticum (Poaceae), Samuel E. Fox, Justin Preece, Jeffrey A. Kimbrel, Gina L. Marchini, Abigail Sage, Ken Youens-Clark, Mitchell B. Cruzan, Pankaj Jaiswal

Biology Faculty Publications and Presentations

Premise of the study: We report the de novo assembly and characterization of the transcriptomes of Brachypodium sylvaticum (slender false-brome) accessions from native populations of Spain and Greece, and an invasive population west of Corvallis, Oregon, USA. Methods and Results: More than 350 million sequence reads from the mRNA libraries prepared from three B. sylvaticum genotypes were assembled into 120,091 (Corvallis), 104,950 (Spain), and 177,682 (Greece) transcript contigs. In comparison with the B. distachyon Bd21 reference genome and GenBank protein sequences, we estimate >90% exome coverage for B. sylvaticum . The transcripts were assigned Gene Ontology and InterPro annotations. Brachypodium …

Distance And Sex Determine Host Plant Choice By Herbivorous Beetles, Daniel J. Ballhorn, Stefanie Kautz, Martin Heil

Biology Faculty Publications and Presentations

Background: Plants respond to herbivore damage with the release of volatile organic compounds (VOCs). This indirect defense can cause ecological costs when herbivores themselves use VOCs as cues to localize suitable host plants. Can VOCs reliably indicate food plant quality to herbivores?

Methodology: We determined the choice behavior of herbivorous beetles (Chrysomelidae: Gynandrobrotica guerreroensis and Cerotoma ruficornis) when facing lima bean plants (Fabaceae: Phaseolus lunatus) with different cyanogenic potential, which is an important constitutive direct defense. Expression of inducible indirect defenses was experimentally manipulated by jasmonic acid treatment at different concentrations. The long-distance responses of male and female beetles to …

Asian Primate Species Richness Correlates With Rainfall, Yi-Chen Wang, Amrita Srivathsan, Chen-Chieh Feng, Agus Salim, Myron Shekelle

Biology Faculty Publications and Presentations

Previous studies of meta-analyses found significantly positive correlations between primate species richness and rainfall for Africa, Madagascar and the Neotropics, with the exception of Asia, leaving the open question whether that anomaly is the result of sampling bias, biogeography, or some other factor. This study re-examines the question using modelled data, with primate species richness data from the Southeast Asian Mammals Databank and rainfall data from the Climatic Research Unit. Data processing with Geographical Information Systems resulted in 390 sample points. Reduced major axis and ordinary least squares regressions were employed to examine the relationship for six regions, including the …