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Articles 1 - 10 of 10
Full-Text Articles in Entire DC Network
Historical Biogeography Of North American Nightsnakes And Their Relationships Among The Dipsadines: Evidence For Vicariance Associated With Miocene Formations Of Northwestern Mexico, Daniel G. Mulcahy
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
I used a hierarchical approach to study historical biogeography in a group of colubrid snakes found in western North America. I combined small regions of mtDNA sequence data from a large number of individuals, with complete mt-genomic data. First, I investigated the relationships among leptodeirines—a presumed subgroup of dipsadines, including nightsnakes (Pseudoleptodeira, Eridiphas, and Hypsiglena)—using ~1.5 kb of data (cob and nad4). The relationships differed among parsimony, likelihood, and Bayesian analyses. All analyses supported the monophyly of the nightsnakes; however, none supported the monophyly of the leptodeirines. Instead, these data supported a new hypothesis …
Emerging Physiological Significance Of R-Type Calcium Currents, Paul Jensen
Emerging Physiological Significance Of R-Type Calcium Currents, Paul Jensen
Undergraduate Honors Capstone Projects
R-type channels are voltage dependent calcium channel subtypes. To date, the only variant of the R-type calcium channel that has been isolated and cloned is the Cav2.3 variant, encoded by the gene Cchral (Yamazaki et al., 1998). The channel was named "R-type" because it was initially characterized by its resistance to nifedipine (a blocker of L-type calcium channels), Ω-conotoxin GVIA (an N-type calcium channel blocker) and Ω -Aga IVA (a blocker of P/Q-type calcium channels) (Hille 2001). The Cav2.3 calcium channel is selectively inhibited by the peptide SNX-482, which was isolated from venom of the African …
Regulation Of Cardiac Fibroblast Metalloprotease Secretion, Glen De Guzman
Regulation Of Cardiac Fibroblast Metalloprotease Secretion, Glen De Guzman
Undergraduate Honors Capstone Projects
Matrix metalloproteases (MMPs) are proteolytic enzymes secreted by cardiac fibroblasts. Altered expression of MMPs plays an important role in congestive heart failure and other cardiovascular diseases1,2. Emerging evidence has led us to consider the role of phosphatidylinositol 4-kinase (PtdIns 4-kinase) in regulating MMP secretion in cardiac fibroblast cells3-7. PtdIns 4-kinase is a lipid kinase involved in various cellular processes including protein secretion. This project was designed to test the hypothesis that PtdIns 4-kinase controls MMP secretion. Techniques such as cardiac cell culture, transfection, and in-gel zymography were used for this experiment. Results demonstrated that PtdIns 4-kinase …
Modulation Of Fast And Slow Inactivation In Two Cardiac Nav Channel Isoforms By Sdz 211-939, Tyce Jeffrey Kearl
Modulation Of Fast And Slow Inactivation In Two Cardiac Nav Channel Isoforms By Sdz 211-939, Tyce Jeffrey Kearl
Undergraduate Honors Capstone Projects
Here we report a hitherto unknown effect of a synthetic inactivation inhibitor on inactivation in cardiac sodium channels (Nav1.5) from two different species: human and bovine. SDZ 211-93 9 stabilized the slow inactivated-state in both channels as seen by an increased steady-state probability of slow inactivation. SDZ also destabilized the fast-inactivated state and increased the amplitude of persistent currents. SDZ modulated conductance parameters, open-state fast inactivation time constants, and activation kinetics of hNav1.5, but not bNav1.5. These findings will aid future studies designed to elucidate the binding site and molecular mechanisms of inactivation inhibitors …
Terpenes And Carbohydrate Source Influence Rumen Fermentation, Digestibility, Intake, And Preference In Sheep, J. J. Villalba, F. D. Provenza, K. C. Olson
Terpenes And Carbohydrate Source Influence Rumen Fermentation, Digestibility, Intake, And Preference In Sheep, J. J. Villalba, F. D. Provenza, K. C. Olson
Green Canyon Environmental Research Area, Logan Utah
We hypothesized that toxins and nutrients in foods interact to influence foraging behavior by herbivores. Based on this hypothesis we predicted that 1) terpenes in big sagebrush (Artemisia tridentata) influence intake and preference in sheep for diets varying in sources of nonstructural (barley grain) and structural (sugar beet pulp) carbohydrates, and 2) these effects are due to the differential effects of terpenes on fermentation products and apparent digestibility of each class of carbohydrates. Lambs were fed 2 isoenergetic and isonitrogenous diets with varying proportions of the same ingredients (beet pulp- and barley grain-based diet) or offered a choice between the …
Intra-Guild Compensation Regulates Species Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown
Intra-Guild Compensation Regulates Species Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown
Biology Faculty Publications
Null models have had a long and contentious history in community ecology (Connor and Simberloff 1979, Harvey et al. 1983, Gotelli and Graves 1996, Graves and Rahbek 2005). Much of this debate has arisen because multiple strategies for null models can be used to address a particular question of interest, and the present exchange is no exception. To assess constancy in species richness through time in a desert rodent community, Nichols et al. (2006) have proposed a Markov Chain model as an alternative to the random-walk model we developed (Goheen et al. 2005). While both null models simulate stochastic local …
Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, K D. Gilliland, Nancy J. Huntly, J E. Anderson
Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, K D. Gilliland, Nancy J. Huntly, J E. Anderson
Biology Faculty Publications
Many desert perennials are long-lived, but there are few data on ages or population structures of desert plants. We used 2 methods to estimate ages of a population of Yucca brevifolia (Joshua tree) in southwestern Utah from a 14-year census of plant sizes. Plant height at the 1st census ranged from 0.08 m to 6.0 m, and trees grew in height at a mean rate of 3.75 cm ⋅ yr–1. Plants also increased slowly in basal diameter (0.142 cm ⋅ yr–1) and branch length (0.024 m ⋅ yr–1), but basal diameter varied greatly from year to year, with many plants …
A Comparison Of The Species-Time Relationship Across Ecosystems And Taxonomic Groups, Ethan P. White, P. B. Adler, W. K. Lauenroth, R. A. Gill, D. Greenberg, D. M. Kaufman, A. Rassweiler, J. A. Rusak, M. D. Smith, J. R. Steinbeck, R. B. Waide, J. Yao
A Comparison Of The Species-Time Relationship Across Ecosystems And Taxonomic Groups, Ethan P. White, P. B. Adler, W. K. Lauenroth, R. A. Gill, D. Greenberg, D. M. Kaufman, A. Rassweiler, J. A. Rusak, M. D. Smith, J. R. Steinbeck, R. B. Waide, J. Yao
Biology Faculty Publications
The species-time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This pattern has numerous implications for both theory and conservation in much the same way as the speciesarea relationship (SAR). However, the STR has received much less attention and to date only a handful of papers have been published on the pattern. Here we gather together 984 community time-series, representing 15 study areas and 9 taxonomic groups, and evaluate their STRs in order to assess the generality of the STR, its consistency across ecosystems and taxonomic groups, …
Intra-Guild Compensation Regulatesspecies Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown
Intra-Guild Compensation Regulatesspecies Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown
Biology Faculty Publications
No abstract provided.
The Offspring/Clutch Size Tradeoff In Mammals, E. L. Charnov, S.K. Morgan Ernest
The Offspring/Clutch Size Tradeoff In Mammals, E. L. Charnov, S.K. Morgan Ernest
Biology Faculty Publications
The Smith‐Fretwell model for optimal offspring size assumes the existence of an inverse proportional relationship (i.e., trade‐off) between the number of offspring and the amount of resources invested in an individual offspring; virtually all of the many models derived from theirs make the same trade‐off assumption. Over the last 30 years it has become apparent that the predicted proportionality is often not observed when evaluated across species. We develop a general allometric approach to correct for size‐related differences in the resources available for reproduction. Using data on mammals, we demonstrate that the predicted inverse proportional relationship between number of offspring …