Digital Commons Network^™

Deer Mouse Hemoglobin Exhibits A Lowered Oxygen Affinity Owing To Mobility Of The E Helix, Noriko Inoguchi, Jake R. Oshlo, Chandrasekhar Natarajan, Roy E. Weber, Angela Fago, Jay F. Storz, Hideaki Moriyama

School of Biological Sciences: Faculty Publications

The deer mouse, Peromyscus maniculatus, exhibits altitude-associated variation in hemoglobin oxygen affinity. To examine the structural basis of this functional variation, the structure of the hemoglobin was solved. Recombinant hemoglobin was expressed in Escherichia coli and was purified by ion-exchange chromatography. Recombinant hemoglobin was crystallized by the hangingdrop vapor-diffusion method using polyethylene glycol as a precipitant. The obtained orthorhombic crystal contained two subunits in the asymmetric unit. The refined structure was interpreted as the aquo-met form. Structural comparisons were performed among hemoglobins from deer mouse, house mouse and human. In contrast to human hemoglobin, deer mouse hemoglobin lacks the …

Holocarboxylasesynthetase Interacts Physically With Euchromatic Histone-Lysine N-Methyltransferase, Linking Histone Biotinylation With Methylation Events, Yong Li, Yousef I. Hassan, Hideaki Moriyama, Janos Zempleni

School of Biological Sciences: Faculty Publications

Holocarboxylasesynthetase (HCS) catalyzes the binding of the vitamin biotin to histonesH3 and H4, thereby creating rare histonebiotinylation marks in the epigenome. These marksco-localize with K9-methylated histone H3 (H3K9me), an abundant gene repression mark. The abundance of H3K9me marks in transcriptionally competent loci decreases when HCS is knocked down and when cells are depleted of biotin. Here we tested the hypothesis that the creation of H3K9me marks is at least partially explained by physical interactions between HCS and histone-lysine Nmethyltransferases. Using a novel in silico protocol, we predicted that HCS-interacting proteins contain a GGGG(K/R)G(I/M)R motif. Thismotif, with minor variations, is present …

Bile-Acid-Mediated Decrease In Endoplasmic Reticulum Stress: A Potential Contributor To The Metabolic Benefits Of Ileal Interposition Surgery In Ucd-T2dm Rats, Bethany P. Cummings, Ahmed Bettaieb, James L. Graham, Jaehyoung Kim, Fangrui Ma, Noreene Shibata, Kimber L. Stanhope, Cecilia Giulivi, Frederik Hansen, Jacob Jelsing, Niels Vrang, Mark Kowala, Michael L. Chouinard, Fawaz G. Haj, Peter J. Havel

Nebraska Center for Biotechnology: Faculty and Staff Publications

Post-operative increases in circulating bile acids have been suggested to contribute to the metabolic benefits of bariatric surgery; however, their mechanistic contributions remain undefined. We have previously reported that ileal interposition (IT) surgery delays the onset of type 2 diabetes in UCD-T2DM rats and increases circulating bile acids, independently of effects on energy intake or body weight. Therefore, we investigated potential mechanisms by which post-operative increases in circulating bile acids improve glucose homeostasis after IT surgery. IT, sham or no surgery was performed on 2-month-old weight-matched male UCD-T2DM rats. Animals underwent an oral fat tolerance test (OFTT) and serial oral …

Plant Mitochondrial Genome Evolution Can Be Explained By Dna Repair Mechanisms, Alan C. Christensen

School of Biological Sciences: Faculty Publications

Plant mitochondrial genomes are notorious for their large and variable size, nonconserved open reading frames of unknown function, and high rates of rearrangement. Paradoxically, the mutation rates are very low. However, mutation rates can only be measured in sequences that can be aligned—a very small part of plant mitochondrial genomes. Comparison of the complete mitochondrial genome sequences of two ecotypes of Arabidopsis thaliana allows the alignment of noncoding as well as coding DNA and estimation of the mutation rates in both. A recent chimeric duplication is also analyzed. A hypothesis is proposed that the mechanisms of plant mitochondrial DNA repair …

The Mid-Domain Effect: It’S Not Just About Space, Andrew D. Letten, S. Kathleen Lyons, Angela T. Moles

School of Biological Sciences: Faculty Publications

Ecologists and biogeographers have long sought to understand how and why diversity varies across space. Up until the late 20th century, the dominant role of environmental gradients and historical processes in driving geographical species richness patterns went largely undisputed. However, almost 20 years ago, Colwell & Hurtt (1994) proposed a radical reappraisal of ecological gradient theory that called into question decades of empirical and theoretical research. That controversial idea was later termed the ‘the mid-domain effect’: the simple proposition that in the absence of environmental gradients, the random placement of species ranges within a bounded domain will give rise to …

Nitrogen Uptake Strategies Of Edaphically Specialized Bornean Tree Species, Sabrina E. Russo, Amy Kochsiek, Jocelyn Olney, Lauren Thompson, Amy E. Miller, Sylvester Tan

School of Biological Sciences: Faculty Publications

The association of tree species with particular soil types contributes to high b diversity in forests, but the mechanisms producing such distributions are still debated. Soil nitrogen (N) often limits growth and occurs in differentially available chemical forms. In a Bornean forest where tree species composition changes dramatically along a soil gradient varying in supplies of different N-forms, we investigated whether tree species’ N-uptake and soil specialization strategies covaried. We analyzed foliar ¹⁵N natural abundance for a total of 216 tree species on clay or sandy loam (the soils at the gradient’s extremes) and conducted a ¹⁵N-tracer experiment …

Paleoparasitology: The Origin Of Human Parasites; Paleoparasitologia: A Origem Dos Parasitas Humanos, Adauto Araújo, Karl Reinhard, Luis Fernando Ferreira, Elisa Pucu, Pedro Paulo Chieffi

Karl Reinhard Publications

Parasitism is composed by three subsystems: the parasite, the host, and the environment. There are no organisms that cannot be parasitized. The relationship between a parasite and its host species most of the time do not result in damage or disease to the host. However, in a parasitic disease the presence of a given parasite is always necessary, at least in a given moment of the infection. Some parasite species that infect humans were inherited from pre-hominids, and were shared with other phylogenetically close host species, but other parasite species were acquired from the environment as humans evolved. Human migration …

Ten Misconceptions Concerning Neurobiology And Politics, John R. Hibbing

Department of Political Science: Faculty Publications

Political science is far behind the other social science disciplines in incorporating neurobiological concepts, techniques, and theory. In recent years progress has been made in closing this gap but many in the political science mainstream view the movement with concern or even horror. Though a healthy dose of skepticism is appropriate and beneficial to the scientific endeavor, negative reactions to viewing politics through a neurobiological lens are often based on fundamental misconceptions regarding both neurobiology and politics. In this Reflections essay, I address ten of these misconceptions, including the beliefs that biology is deterministic, reductionist, unnecessary, irrelevant, normatively dangerous, and …

Carbon Storage And Sequestration By Trees In Urban And Community Areas Of The United States, David J. Nowak, Eric J. Greenfield, Robert E. Hoehn, Elizabeth Lapoint

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Carbon storage and sequestration by urban trees in the United States was quantified to assess the magnitude and role of urban forests in relation to climate change. Urban tree field data from 28 cities and 6 states were used to determine the average carbon density per unit of tree cover. These data were applied to statewide urban tree cover measurements to determine total urban forest carbon storage and annual sequestration by state and nationally. Urban whole tree carbon storage densities average 7.69 kg C m^‒2 of tree cover and sequestration densities average 0.28 kg C m^‒2 of tree …

Modeling Harvest And Biomass Removal Effects On The Forest Carbon Balance Of The Midwest, Usa, Scott D. Peckham, Stith T. Gower, Charles H. Perry, Barry T. Wilson, Kirk M. Stueve

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

The objective of this study was to use an ecosystem process model, Biome-BGC, to explore the effects of different harvest scenarios on major components of the carbon budget of 205,000 km² of temperate forest in the Upper Midwest region of the U.S. We simulated seven harvest scenarios varying the (i) amount of harvest residue retained, (ii) total harvest area, and (iii) harvest type (clear-cut and selective) to assess the potential impacts on net biome production (NBP), net primary production (NPP), and total vegetation carbon. NBP was positive (C sink) in year 1 (2004) and generally decreased over the 50-year …

Evaluating Population Connectivity For Species Of Conservation Concern In The American Great Plains, Samuel A. Cushman, Erin L. Landguth, Curtis H. Flather

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Habitat loss and fragmentation are widely recognized as among the most important threats to global biodiversity. New analytical approaches are providing an improved ability to predict the effects of landscape change on population connectivity at vast spatial extents. This paper presents an analysis of population connectivity for three species of conservation concern [swift fox (Vulpes velox); lesser prairie-chicken (Tympanuchus pallidicinctus); massasuaga (Sistrurus catenatus)] across the American Great Plains region. We used factorial least-cost path and resistant kernel analyses to predict effects of landscape conditions on corridor network connectivity. Our predictions of population connectivity provide …

A Comparison Of Dem-Based Indexes For Targeting The Placement Of Vegetative Buffers In Agricultural Watersheds, Mike Dosskey, Zeyuan Qiu, Yang Kang

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Targeted placement of vegetative buffers may increase their effectiveness for improving water quality in agricultural watersheds. The use of digital elevation models (DEMs) enables precise mapping of runoff pathways for identifying where greater runoff loads can be intercepted and treated with buffers. Five different DEM-based targeting indexes were compared and contrasted for the degree to which they identify similar locations in watersheds: Flow Accumulation [S.K. Jenson and J.O. Domingue (1988). Photogrammetric Engineering and Remote Sensing 54:1593], Wetness Index [I.D. Moore, R.B. Grayson, and A.R. Ladson (1991). Hydrological Processes 5:3], Topographic Index [M.T. Walter, T.S. Steenhuis, V.K. Mehta, D. Thongs, M. …

Turbidity And Suspended-Sediment Changes From Stream-Crossing Construction On A Forest Haul Road In West Virginia, Usa, Jingxin Wang, Pamela J. Edwards, Frederica Wood

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

A forested headwater watershed in West Virginia was monitored to examine changes to in-stream turbidity following the construction of a 0.92 km (0.57 mi) haul road. Due to the design of the study, most of the sediment that entered the stream following road construction was known to result from the stream crossings and approaches to the crossings. Stream-water samples collected daily and sequentially during stormflow from 1999 through 2005 were used to interpret the effects of stream-crossing construction on turbidity and suspended-sediment concentrations (SSC). Daily and stormflow turbidity and SSC values increased as a result of the construction. Average sediment …

Development History And Bibliography Of The U.S. Forest Service Crown-Condition Indicator For Forest Health Monitoring, Kadonna C. Randolph

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Comprehensive assessment of individualtree crown condition by the US Department of Agriculture, Forest Service, Forest Inventory and Analysis (FIA) Program has its origins in the concerns about widespread forest decline in Europe and North America that developed in the late 1970s and early 1980s. Programs such as the US National Acid Precipitation Assessment Program, US National Vegetation Survey, Canadian Acid Rain National Early Warning System, and joint US– Canadian North American Sugar Maple Decline Project laid the groundwork for the development of the US Forest Service crown-condition indicator. The crown-condition assessment protocols were selected and refined through literature review, peer …

Small Geographic Range But Not Panmictic: How Forests Structure The Endangered Point Arena Mountain Beaver (Aplodontia Rufa Nigra), William J. Zielinski, Fredrick V. Schlexer, Sean A. Parks, Kristine L. Pilgrim, Michael K. Schwartz

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

The landscape genetics framework is typically applied to broad regions that occupy only small portions of a species’ range. Rarely is the entire range of a taxon the subject of study. We examined the landscape genetic structure of the endangered Point Arena mountain beaver (Aplodontia rufa nigra), whose isolated geographic range is found in a restricted (85 km²) but heterogenous region in California. Based on its diminutive range we may predict widespread gene flow and a relatively weak role for landscape variation in defining genetic structure. We used skin, bone, tissue and noninvasively collected hair samples …

Riparian Vegetation Communities Change Rapidly Following Passive Restoration At A Northern Utah Stream, Nate Hough-Snee, Brett B. Roper, Joseph M. Wheaton, Phaedra Budy, Ryan L. Lokteff

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Riparian vegetation may recover quickly from disturbance when the disturbance vector is removed or reduced. Grazing is a disturbance that removes plant biomass through herbivory, while overgrazing is a more severe disturbance that can deplete plant propagule pools and inhibit plant community recovery. We tested the hypothesis that riparian vegetation communities can shift quickly from ruderal grasslands to hydrophytic shrubs and graminoids when grazing is largely eliminated from riparian areas. We used a before-after-control study design to collect vegetation community data at six restored reaches and two grazed control reaches prior to and immediately following the construction of a cattle …

Interactions Between An Injected Polydnavirus And Per Os Baculovirus In Gypsy Moth Larvae, V. D'Amico, J.D. Podgwaite, R. Zerillo, P. Taylor, R. Fuester

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Larval gypsy moths, Lymantria dispar (Lepidoptera:Lymantriidae) were co-infected with the L. dispar nucleopolyhedrovirus (LdMNPV) and the Cotesia melanoscela (Hymenoptera:Braconidae) polydnavirus (CmeBV). CmeBV was given along with a parasitoid egg and calyx products in a stinging event, or in the form of an injection of calyx-derived extract. LdMNPV was delivered per os, integrated into artificial diet. Mortality from all sources was recorded over the subsequent three-week period. Neither parasitism nor injections of purified CmeBV with toxin had any effect on the amount of mortality caused by concurrent challenges with LdMNPV.

Bird Response To Fire Severity And Repeated Burning In Upland Hardwood Forest, Cathryn H. Greenberg, Thomas A. Waldrop, Joseph Tomcho, Ross J. Phillips, Dean Simon

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Prescribed burning is a common management tool for upland hardwood forests, with wildlife habitat improvement an often cited goal. Fire management for wildlife conservation requires understanding how species respond to burning at different frequencies, severities, and over time. In an earlier study, we experimentally assessed how breeding bird communities and species responded to fuel reduction treatments by mechanical understory reduction, low-severity prescribed fires, or mechanical understory reduction followed a year later by high-severity prescribed fires in upland hardwood forest. Here, we assess longer-term response to the initial mechanical treatment (M), and a second low-intensity burn in twice burned (B2) and …

Soil Carbon And Nitrogen Content And Stabilization In Mid-Rotation, Intensively Managed Sweetgum And Loblolly Pine Stands, Kurt H. Johnson, Lisa J. Samuelson, Felipe G. Sanchez, Robert J. Eaton

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Intensive forestry has resulted in considerable increases in aboveground stand productivity including foliar and belowground biomass which are the primary sources of soil organic matter. Soil organic matter is important for the maintenance of soil physical, chemical and biological quality. Additionally, sequestering carbon (C) in soils may provide a means of mitigating increasing atmospheric carbon dioxide concentrations. In this study, we examined soil C and nitrogen (N) contents and stabilization in 12-year-old, intensively managed sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.) stands. The treatments examined include: (1) complete weed control; (2) weed control plus drip irrigation; (3) …

Stand- And Landscape-Scale Selection Of Large Trees By Fishers In The Rocky Mountains Of Montana And Idaho, Michael K. Schwartz, Nicholas J. Decesare, Benjamin S. Jimenez, Jeffrey P. Copeland, Wayne E. Melquist

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

The fisher (Pekania pennanti; formerly known as Martes pennanti) is a North American endemic mustelid with a geographic distribution that spans much of the boreal forests of North America. In the Northern Rocky Mountain (NRM) fishers have been the focus of Endangered Species Act (ESA) listing decisions. Habitat studies of West Coast fishers in California have consistently identified late-successional forests as important, providing direct implications for forest management and fisher conservation. In the NRM range very little is known about the habitat selection patterns of fishers relative to forest age and species composition, yet ESA petitioners have repeatedly listed habitat …

Forest Recovery Patterns In Response To Divergent Disturbance Regimes In The Border Lakes Region Of Minnesota (Usa) And Ontario (Canada), Brian R. Sturtevant, Brian R. Miranda, Peter T. Wolter, Patrick M.A. James, Marie-Josée Fortin, Philip A. Townsend

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

The persistence of landscape-scale disturbance legacies in forested ecosystems depends in part on the nature and strength of feedback among disturbances, their effects, and subsequent recovery processes such as tree regeneration and canopy closure. We investigated factors affecting forest recovery rates over a 25-year time period in a large (6 million ha) landscape where geopolitical boundaries have resulted in important land management legacies (managed forests of Minnesota, USA; managed forests of Ontario, Canada; and a large unmanaged wilderness). Stand-replacing disturbance regimes were quantified across management zones, both inside and outside a central ecoregion, using a time series of classified land …

A Wildfire Risk Assessment Framework For Land And Resource Management, Joe H. Scott, Matthew P. Thompson, David E. Calkin

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Wildfires can result in significant, long-lasting impacts to ecological, social, and economic systems. It is necessary, therefore, to identify and understand the risks posed by wildland fire, and to develop cost-effective mitigation strategies accordingly. This report presents a general framework with which to assess wildfire risk and explore mitigation options, and illustrates a process for implementing the framework. Two key strengths of the framework are its flexibility— allowing for a multitude of data sources, modeling techniques, and approaches to measuring risk—and its scalability, with potential application for project, forest, regional, and national planning. The specific risk assessment process we introduce …

Integrating Biodiversity And Drinking Water Protection Goals Through Geographic Analysis, James D. Wickham, Curtis H. Flather

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

Aim Biodiversity and drinking water share a common interest in land conservation. Our objective was to identify where that common interest occurs geographically to inform conservation planning.

Location The study focused on 2112 eight-digit hydrologic units (watersheds) occurring in the conterminous United States.

Methods Data on aquatic-dependent species occurrence, drinking water intakes, protected land status and land cover change were compiled for each watershed. We compared these four datasets after defining ‘hotspots’ based on attribute-specific thresholds that included (1) the 90th percentile of at-risk aquatic biodiversity, (2) with and without drinking water intakes, (3) above and below the median percentage …

Wildlife Population And Harvest Trends In The United States A Technical Document Supporting The Forest Service 2010 Rpa Assessment, Curtis H. Flather, Michael S. Knowles, Martin F. Jones, Carol Schilli

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

The Forest and Rangeland Renewable Resources Planning Act (RPA) of 1974 requires periodic assessments of the condition and trends of the nation’s renewable natural resources. Data from many sources were used to document recent historical trends in big game, small game, migratory game birds, furbearers, nongame, and imperiled species. Big game and waterfowl have generally increased in population and harvest trends. Many small upland and webless migratory game bird species have declined notably in population or harvest. Considerable declines in fur harvest since the 2000 RPA Assessment have occurred. Among the 426 breeding bird species with sufficient data to estimate …

The Influence Of Vertical And Horizontal Habitat Structure On Nationwide Patterns Of Avian Biodiversity, Patrick D. Culbert, Volker C. Radeloff, Curtis H. Flather, Josef M. Kellndorfer, Chadwick D. Rittenhouse, Anna M. Pidgeon

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

With limited resources for habitat conservation, the accurate identification of high-value avian habitat is crucial. Habitat structure affects avian biodiversity but is difficult to quantify over broad extents. Our goal was to identify which measures of vertical and horizontal habitat structure are most strongly related to patterns of avian biodiversity across the conterminous United States and to determine whether new measures of vertical structure are complementary to existing, primarily horizontal, measures. For 2,546 North American Breeding Bird Survey routes across the conterminous United States, we calculated canopy height and biomass from the National Biomass and Carbon Dataset (NBCD) as measures …

Keeping It Wild: Mapping Wilderness Character In The United States, Steve Carver, James Tricker, Peter Landres

United States Department of Agriculture, Forest Service / University of Nebraska-Lincoln: Faculty Publications

A GIS-based approach is developed to identify the state of wilderness character in US wilderness areas using Death Valley National Park (DEVA) as a case study. A set of indicators and measures are identified by DEVA staff and used as the basis for developing a flexible and broadly applicable framework to map wilderness character using data inputs selected by park staff. Spatial data and GIS methods are used to map the condition of four qualities of wilderness character: natural, untrammelled, undeveloped, and solitude or primitive and unconfined recreation. These four qualities are derived from the US 1964 Wilderness Act and …

Does Fertility Status Influence Impulsivity And Risk Taking In Human Females? Adaptive Influences On Intertemporal Choice And Risky Decision Making, Farnaz Kaighobadi,, Jeffrey R. Stevens

Department of Psychology: Faculty Publications

Informed by the research on adaptive decision making in other animal species, this study investigated human females’ intertemporal and risky choices across the ovulatory cycle. We tested the hypothesis that at peak fertility, women who are exposed to environments that signal availability of higher quality mates (by viewing images of attractive males), become more impulsive and risk-seeking in economic decision tasks. To test this, we collected intertemporal and risky choice measures before and after exposure to images of either attractive males or neutral landscapes both at peak and low fertility conditions. The results showed an interaction between women’s fertility status …

Ovulation, In Vivo Emotion Regulation Problems, And Sexual Risk Recognition Deficits, Kate Walsh, David Dilillo

Department of Psychology: Faculty Publications

Objective: To examine associations between menstrual cycle phase, negative mood, sexual risk recog-nition deficits (assessed via an analogue risk vignette), and in vivo emotion dysregulation. Partici-pants: Participants were 714 college women recruited between February 2007 and December 2009. Methods: Participants were randomly assigned to a negative or neutral mood induction and in-structed to identify sexual risk during an audiotaped sexual coercion vignette. Participants reported menstrual cycle information, in vivo emotional nonacceptance, and attention during the vignette. Results: In the negative mood condition, ovulation was associated with longer risk recognition laten-cies relative to the luteal and follicular phases of the menstrual …

Effects Of Body Position And Sex Group On Tongue Pressure Generation, Angela M. Dietsch, Carmen M. Cirstea, Ed T. Auer, Jeff P. Searl

Department of Special Education and Communication Disorders: Faculty Publications

Fine control of orofacial musculature is necessary to precisely accelerate and decelerate the articulators across exact distances for functional speech and coordinated swallows. Enhanced understanding of neural control for such movements could clarify the nature of and potential remediation for some dysarthrias and other orofacial myofunctional impairments. Numerous studies have measured orolingual force and accuracy during speech and nonspeech tasks, but have focused on young adults, maximum linguapalatal pressures, and upright positioning. Patients’ medical conditions or testing procedures such as concurrent neuroimaging may preclude fully upright positioning during oral motor assessments in some cases. Since judgments about lingual strength and …

Effects Of Environmental Stimulation On Infant Vocalizations And Orofacial Dynamics At The Onset Of Canonical Babbling, Meredith Poore Harold, Steven M. Barlow

Department of Special Education and Communication Disorders: Faculty Publications

The vocalizations and jaw kinematics of 30 infants aged 6–8 months were recorded using a Motion Analysis System and audiovisual technologies. This study represents the first attempt to determine the effect of play environment on infants’ rate of vocalization and jaw movement. Four play conditions were compared: watching videos, social contingent reinforcement and vocal modeling with an adult, playing alone with small toys, and playing alone with large toys. The fewest vocalizations and spontaneous movement were observed when infants were watching videos or interacting with an adult. Infants vocalized most when playing with large toys. The small toys, which naturally …