Digital Commons Network^™

Levels And Changes Of Soil Phosphorus In Subtropical Beef Cattle Pastures, Gilbert C. Sigua, Mary J. Williams, Samuel W. Coleman

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Long-term pasture management is believed to change soil chemical properties, but little is known about whether pasture management, such as fertilizer application, grazing, or haying can initiate such change in sandy and well-drained subtropical beef pastures. The objective of this study was to investigate the long term effect of pasture management (grazing+haying, GZ+HY) on soil phosphorus (P) dynamics (levels and changes) in subtropical beef cattle pastures with bahiagrass (BG, Paspalum notatum) and rhizoma peanut (RP, Arachis glabrata) with (WP) or without (WNP) P fertilization in Brooksville, FL from 1988 to 2000. Soil P dynamics in Subtropical Agricultural Research …

Habitat Manipulation Of The Apple Orchard Floor To Increase Ground-Dwelling Predators And Predation Of Cydia Pomonella (L.) (Lepidoptera: Tortricidae), Clarissa R. Mathews, Dale G. Bottrell, M. W. Brown

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Augmenting generalist predator populations in new apple (Malus domestica Bork) plantings could potentially aid in the establishment of balanced orchard ecosystems that are less susceptible to pest outbreaks. Habitat can be an important factor in retaining predators in a system and can affect predator efficiency. We investigated the potential of increasing a complex of generalist ground-dwelling predators and enhancing biological control in a young 'Golden Delicious' apple orchard through ground habitat manipulation. We modified the orchard floor with four comparative habitat treatments: (1) detritus-rich compost mulch layer, (2) detritus-free synthetic mulch layer, (3) herbicide-treated vegetation thatch, and (4) bare …

Supercooling Differences In The Eastern Subterranean Termite (Isoptera: Rhinotermitidae), Brian J. Cabrera, Shripat T. Kamble

Department of Entomology: Faculty Publications

Supercooling points were determined for untreated field-collected and untreated laboratory-maintained Reticulitermes flavipes (Kollar) workers and soldiers. Workers treated with antibiotics or had their hindgut-protozoa removed by exposing them to oxygen under pressure to determine the effects of absence of the hindgut fauna on supercooling. Supercooling points were compared be-tween live and freshly killed workers to determine whether supercooling in this species might be simply due to the biochemical properties of body fluids. Laboratory-maintained workers were also subjected to desiccation, starvation, or atmospheric pressure to determine their effects on supercool-ing. Supercooling points were lowest for laboratory workers treated with antibiotics and …

Phospholipase A2 In Salivary Glands Isolated From Tobacco Hornworms, Manduca Sexta, Hasan Tunaz, David W. Stanley

Department of Entomology: Faculty Publications

We describe a phospholipase A₂ (PLA₂) associated with the salivary glands of tobacco hornworms, Manduca sexta. This enzyme is able to hydrolyze arachidonic acid from the sn-2 position of PLs. Addition of the calcium chelator, EGTA, or calcium, to the Tris reaction buffer impaired the PLA₂ activity, from which we infer the enzyme requires very low concentrations of calcium or perhaps other ions for optimal activity. PLA₂ activity was sensitive to protein concentration (highest activity at 25 μg protein per μl), reaction time (optimal at 30 min), buffer pH (optimal at pH 8–10), …

Guidelines For Managing Lesser Prairie-Chicken Populations And Their Habitats, Christian A. Hagen, Brent E. Jamison, Kenneth M. Giesen, Terry Z. Riley

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

Lesser prairie-chicken (Tympanuchus paidicinctus) populations have declined by >90% since the 1800s. These declines have concerned both biologists and private conservation groups and led to a petition to list the lesser prairie-chicken as threatened under the Endangered Species Act. Most of the land in the current range of the lesser prairie-chicken is privately owned, and declines have been primarily attributed to anthropogenic factors. Conversion of native rangeland to cropland and excessive grazing have been implicated as leading causes in the species' decline. Periodic drought probably has exacerbated these problems. Little research on habitat requirements was conducted prior to …

Patterns Of Variation In Clutch Sizes In A Guild Of Temperate-Nesting Dabbling Ducks, Gary Krapu, Ronald Reynolds, Glen Sargeant, Randy Renner

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

We investigated patterns and causes of variation in clutch sizes in a guild of five species of temperate-nesting dabbling ducks (Mallard [Anas platyrhynchos], Northern Pintail [“pintail,” A. acuta], Gadwall [A. strepera], Blue-winged Teal [“teal,” A. discors], and Northern Shoveler [“shoveler,” A. clypeata]) during 1993–1995 in the Prairie Pothole Region of midcontinental North America. Clutch sizes (mean ± SE) were largest for teal (10.80 ± 0.03), followed in descending order by those of shoveler (10.31 ± 0.05), Gadwall (9.92 ± 0.04), Mallard (8.91 ± 0.04), and pintail (7.66 ± 0.06). In Mallard, pintail, and …

Less Waste Corn, More Land In Soybeans, And The Switch To Genetically Modified Crops: Trends With Important Implications For Wildlife Management, Gary L. Krapu, David A. Brandt, Robert R. Cox Jr.

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

American agriculture has provided abundant high-energy foods for migratory and resident wildlife populations since the onset of modern wildlife management. Responding to anecdotal evidence that corn residues are declining in cropland, we remeasured waste corn postharvest in the Central Platte River Valley (CPRV) of Nebraska during 1997 and 1998 to compare with 1978. Post-harvest waste corn averaged 2.6% and 1.8% of yield in 1997 and 1998, respectively. After accounting for a 20% increase in yield, waste corn in 1997 and 1998 was reduced 24% and 47% from 1978. We also evaluated use of soybeans by spring-staging sandhill cranes ( Grus …

Tracking Of White-Tailed Deer Migration By Global Positioning System, Michael Nelson, L. David Mech, Paul F. Frame

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

We used global positioning system (GPS) radiocollars on female white-tailed deer (Odocoileus virginianus) to document details of onsets of migrations, rates of travel, patterns of travel, durations of migrations, and distances traveled by 8 deer in spring and 4 deer in autumn in northeastern Minnesota in 1998, 1999, and 2001. In spring, deer migrated 23–45 km during 31–356 h, deviating a maximum 1.6–4.0 km perpendicular from a straight line of travel between their seasonal ranges. They migrated a minimum of 2.1–18.6 km/day over 11–56 h during 2–14 periods of travel. Minimum travel during 1-h intervals averaged 1.5 km/h …

Is Climate Change Affecting Wolf Populations In The High Artic?, L. David Mech

United States Geological Survey, Northern Prairie Wildlife Research Center: Publications

Gobal climate change may affect wolves in Canada’s High Arctic (80◦ N) acting through three trophic levels (vegetation, herbivores, and wolves). A wolf pack dependent on muskoxen and arctic hares in the Eureka area of Ellesmere Island denned and produced pups most years from at least 1986 through 1997. However, when summer snow covered vegetation in 1997 and 2000 for the first time since records were kept, halving the herbivore nutrition-replenishment period, muskox and hare numbers dropped drastically, and the area stopped supporting denning wolves through 2003. The unusual weather triggering these events was consistent with global-climate-change phenomena.

Seasonal Activity Areas Of Coyotes In The Bear River Mountains Of Utah And Idaho, Glen F. Gantz, Frederick F. Knowlton

United States Department of Agriculture Wildlife Services: Staff Publications

We studied the seasonal movement patterns and dispersal of coyotes (Canis latrans) in the Bear River Mountains of northern Utah and southern Idaho to determine whether coyotes in this montane region exhibit an altitudinal migration on a seasonal basis. We used 3 locational parameters to assess whether a seasonal altitudinal migration was evident, including overlap in seasonal activity areas, distance between harmonic mean centers of activity, and seasonal differences in mean elevations of locations. Winter and summer activity areas of every mature coyote overlapped, with mean distances between harmonic centers of seasonal activity of 1.5 km (range = 0.4–3.3 km). …

Predacides For Canid Predation Management, K. A. Fagerstone, J. J. Johnston, P. J. Savarie

United States Department of Agriculture Wildlife Services: Staff Publications

Throughout the livestock industry in the western United States, control of canid predators was considered to be of considerable importance to the livestock industry, especially to sheep producers, who sufkred high losses from coyotes and wolves. In the 19th century, the demand for predator control was communicated to Congress and the western state assemblies, with the result that predator control was provided in western states by the Fedcral Bureau of Biological Survey in cooperation with state agencies, and by trappers hired by stockmen. Steel traps and poisons were the principal methods used for predator control during the early years of …

A Conceptual Framework For Non-Kin Food Sharing: Timing And Currency Of Benefits, Jeffrey R. Stevens, Ian C. Gilby

Jeffrey Stevens Publications

Many animal species, from arthropods to apes, share food. This paper presents a new framework that categorizes nonkin food sharing according to two axes: (1) the interval between sharing and receiving the benefits of sharing, and (2) the currency units in which benefits accrue to the sharer (especially food versus nonfood). Sharers can obtain immediate benefits from increased foraging efficiency, predation avoidance, mate provisioning, or manipulative mutualism. Reciprocity, trade, status enhancement and group augmentation can delay benefits. When benefits are delayed or when food is exchanged for nonfood benefits, maintaining sharing can become more difficult because animals face discounting and …

Emergence And Survival Of Legumes Seeded Into Pastures Varying In Landscape Position, John A. Guretzky, Kenneth J. Moore, Allen D. Knapp, E. Charles Brummer

Department of Agronomy and Horticulture: Faculty Publications

Landscape position affects legume establishment in pastures. We conducted this study to (i) determine the role of emergence and survival on establishment of legumes on summit and backslope positions and (ii) examine how competition, as influenced by sward-cutting height and N fertilization, affects legume emergence and survival across these positions. We no-till drilled a mixture composed of red clover (Trifolium pratense L.), alfalfa (Medicago sativa L.), and birdsfoot trefoil (Lotus corniculatus L.) into an existing cool-season grass pasture at Rhodes, IA, in 1998 and 1999. Treatments consisted of landscape positions (summit and backslope), N fertilizer rates (0, …

Molecular Mapping And Identification Of Soybean Fatty Acid Modifier Quantitative Trait Loci, D. L. Hyten Jr., Vincent R. Pantalone, Arnold M. Saxton, Michael E. Schmidt, Carl E. Sams

Department of Agronomy and Horticulture: Faculty Publications

Altering FA content in soybean [Glycine max (L.) Merr.] oil for improved functionality is a research goal of many soybean breeders. Several of the genes that alter palmitic, stearic, oleic, linoleic, and linolenic acids are modifier genes with small effects, causing these FA traits to act as quantitative traits. The objective of this study was to identify modifier FA quantitative trait loci (QTL) in soybean. A recombinant inbred line population was created from two prominent ancestors of currently avail-able U.S. cultivars (Essex and Williams) and grown in five environments. One hundred simple se-quence repeat markers spaced throughout the genome …

Changes In Composition And Thermal Transition Temperatures Of Grain Sorghum Wax During Storage, Keum Taek Hwang, Curtis L. Weller, Susan L. Cuppett, Milford Hanna

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Grain sorghum (Sorghum bicolor) wax is composed mainly of aldehydes, alcohols, and acids. Aldehydes, comprising about one-half of the wax, are readily converted to acids in presence of air. In this study, whole sorghum wax and an aldehyde fraction from sorghum wax were subjected to oxidative conditions. Changes in the major components and thermal transition temperatures were determined using HPLC and differential scanning calorimeter (DSC), respectively. The aldehyde fraction was oxidized markedly to acids over 4 months in storage at room temperature. Acid content, in the fraction, was initially 5–7% and increased to 42–51% after 135 days in …

Identification Of Methionine-Rich Clusters That Regulate Copper-Stimulated Endocytosis Of The Human Ctr1 Copper Transporter, Yan Guo

Department of Biochemistry: Faculty Publications

Copper uptake and subsequent delivery to copper-dependent

enzymes are essential for many cellular processes.

However, the intracellular levels of this nutrient

must be controlled because of its potential toxicity. The

hCtr1 protein functions in high affinity copper uptake

at the plasma membrane of human cells. Recent studies

have shown that elevated copper stimulates the endocytosis

and degradation of the hCtr1 protein, and this

response is likely an important homeostatic mechanism

that prevents the overaccumulation of copper. The domains

of hCtr1 involved in copper-stimulated endocytosis

and degradation are unknown. In this study we examined

the importance of potential copper-binding

sequences in …

Mobilization Of Intracellular Copper Stores By The Ctr2 Vacuolar Copper Transporter, Erin M. Rees, Jaekwon Lee, Dennis J. Thiele

Department of Biochemistry: Faculty Publications

Copper plays an essential role in processes including signaling to the transcription and protein trafficking machinery, oxidative phosphorylation, iron mobilization, neuropeptide maturation, and normal development. Whereas much is known about intracellular mobilization of ions such as calcium, little information is available on how eukaryotic cells mobilize intracellular copper stores. We describe a mechanism by which the Saccharomyces cerevisiae Ctr2 protein provides bioavailable copper via mobilization of intracellular copper stores. Whereas Ctr2 exhibits structural similarity to the Ctr1 plasma membrane copper importer, microscopic and biochemical fractionation studies localize Ctr2 to the vacuole membrane. We demonstrate that Ctr2 mobilizes vacuolar copper stores …

Host–Symbiont Stability And Fast Evolutionary Rates In An Ant–Bacterium Association: Cospeciation Of Camponotus Species And Their Endosymbionts, Candidatus Blochmannia, Patrick H. Degnan, Adam B. Lazarus, Chad D. Brock, Jennifer J. Wernegreen

School of Biological Sciences: Faculty Publications

Bacterial endosymbionts are widespread across several insect orders and are involved in interactions ranging from obligate mutualism to reproductive parasitism. Candidatus Blochmannia gen. nov. (Blochmannia) is an obligate bacterial associate of Camponotus and related ant genera (Hymenoptera: Formicidae). The occurrence of Blochmannia in all Camponotus species sampled from field populations and its maternal transmission to host offspring suggest that this bacterium is engaged in a long-term, stable association with its ant hosts. However, evidence for cospeciation in this system is equivocal because previous phylogenetic studies were based on limited gene sampling, lacked statistical analysis of congruence, and have …

Do Harvest Refuges Buffer Kangaroos Against Evolutionary Responses To Selective Harvesting?, Brigitte Tenhumberg, Andrew J. Tyre, Anthony R. Pople, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

There is a wealth of literature documenting a directional change of body size in heavily harvested populations. Most of this work concentrates on aquatic systems, but terrestrial populations are equally at risk. This paper explores the capacity of harvest refuges to counteract potential effects of size-selective harvesting on the allele frequency of populations. We constructed a stochastic, individual-based model parameterized with data on red kangaroos. Because we do not know which part of individual growth would change in the course of natural selection, we explored the effects of two alternative models of individual growth in which alleles affect either the …

High Phosphate (Up To 600 Mm) Induces Pseudohyphal Development In Five Wild Type Candida Albicans, Jacob M. Hornby, Raluca Dumitru, Kenneth Nickerson

Kenneth Nickerson Papers

A method is described for the formation of nearly 100% pseudohyphae populations of wild-type Candida albicans A72. The method employs fungal growth at 37 °C (ca. 5×10⁶ cells/ml) in a glucose–proline–N-acetyl-glucosamine medium supplemented with up to 600 mM phosphate (KH₂PO₄/K₂HPO₄ 1:1) at pH 6.5. Four other strains of C. albicans (MEN, 10261, SG5314 and CAI-4) also formed pseudohyphae under these conditions, although the phosphate response profiles differed in the concentration required for each strain to form pseudohyphae.

Ecological Effects Of Transgenic Crops And The Escape Of Transgenes Into Wild Populations, Diana Pilson, Holly R. Prendeville

School of Biological Sciences: Faculty Publications

Ecological risks associated with the release of transgenic crops include nontarget effects of the crop and the escape of transgenes into wild populations. Nontarget effects can be of two sorts: (a) unintended negative effects on species that do not reduce yield and (b) greater persistence of the crop in feral populations. Conventional agricultural methods, such as herbicide and pesticide application, have large and well- documented nontarget effects. To the extent that transgenes have more specific target effects, transgenic crops may have fewer nontarget effects. The escape of transgenes into wild populations, via hybridization and introgression, could …

Characterization Of The Aspergillus Parasiticus Δ12-Desaturase Gene: A Role For Lipid Metabolism In The Aspergillus–Seed Interaction, Richard A. Wilson, Ana M. Calvo, Perng-Kuang Chang, Nancy P. Keller

Fungal Molecular Plant-Microbe Interactions

In the mycotoxigenic oilseed pathogens Aspergillus flavus and Aspergillus parasiticus and the model filamentous fungus Aspergillus nidulans, unsaturated fatty acids and their derivatives act as important developmental signals that affect asexual conidiospore, sexual ascospore and/or sclerotial development. To dissect the relationship between lipid metabolism and fungal development, an A. parasiticus Δ¹²-desaturase mutant that was unable to convert oleic acid to linoleic acid and was thus impaired in polyunsaturated fatty acid biosynthesis was generated. The Δ¹²-desaturase mutant demonstrates delayed spore germination, a twofold reduction in growth, a reduced level of conidiation and complete loss of sclerotial …

Two Δ9-Stearic Acid Desaturases Are Required For Aspergillus Nidulans Growth And Development, Richard A. Wilson, Perng-Kuang Chang, Agnieszka Dobrzyn, James B. Ntambi, Robert Zarnowski, Nancy P. Keller

Fungal Molecular Plant-Microbe Interactions

Unsaturated fatty acids are important constituents of all cell membranes and are required for normal growth. In the filamentous fungus Aspergillus nidulans, unsaturated fatty acids and their derivatives also influence asexual (conidial) and sexual (ascospore) sporulation processes. To investigate the relationship between fatty acid metabolism and fungal development, we disrupted the A. nidulans sdeA and sdeB genes, both encoding Δ9-stearic acid desaturases responsible for the conversion of palmitic acid (16:0) and stearic acid (18:0) to palmitoleic acid (16:1) and oleic acid (18:1). The effects of sdeA deletion on development were profound, such that growth, conidial and ascospore production were …

A Consensus Protocol For The Determination Of The Threshold Doses For Allergenic Foods: How Much Is Too Much?, S. L. Taylor, S. L. Hefle, C. Bindslev-Jensen, F. M. Atkins, C. Andre, C. Bruijnzeel-Koomen, A. W. Burks, R. K. Bush, M. Ebisawa, P. A. Eigenmann, A. Host, Jonathan O. B. Hourihane, E. Isolauri, D. J. Hill, A. Knulst, G. Lack, H. A. Sampson, D. A. Moneret-Vautrin, F. Rance, P. A. Vadas, J. W. Yunginger, R. S. Zeiger, J. W. Salminen, C. Madsen, P. Abbott

Department of Food Science and Technology: Faculty Publications

Background:While the ingestion of small amounts of an offending food can elicit adverse reactions in individuals with IgE-mediated food allergies, little information is known regarding these threshold doses for specific allergenic foods. While low-dose challenge trials have been conducted on an appreciable number of allergic individuals, a variety of different clinical protocols were used making the estimation of the threshold dose very difficult.

Objective: A roundtable conference was convened to develop a consensus clinical protocol for low-dose challenge trials for the estimation of threshold doses for specific allergenic foods.

Methods: In May 2002, 20 clinical allergists and other interested parties …

Thermal Characteristics Of Wild And Captive Micronesian Kingfisher Nesting Habitats, Dylan C. Kesler, Susan M. Haig

United States Geological Survey: Staff Publications

To provide information for managing the captive population of endangered Guam Micronesian kingfishers (Halcyon cinnamomina cinnamomina), four biologically relevant thermal metrics were compared among captive facilities on the United States mainland and habitats used by wild Micronesian kingfishers on the island of Pohnpei (H. c. reichenbachii), Federated States of Micronesia. Additionally, aviaries where kingfishers laid eggs were compared to those in which birds did not attempt to breed. Compared to aviaries, habitats used by wild Pohnpei kingfishers had 3.2°C higher daily maximum and minimum temperatures and the proportion of time when temperatures were in the birds’ …

2004 Nebraska Grazing Conference, John Owens

John Owens: Speeches and Appearances

It is both my privilege and pleasure to have the opportunity this morning to welcome you to the 2004 Nebraska Grazing Conference. I am sure you are looking forward to the next two days of great topics and excellent speakers. This is the fourth year this conference has brought people together to hear, to discuss, to exchange a wide variety of ideas. Reading through the list of conference sponsors and supporters, I think how fortunate we are in Nebraska to forge and foster such productive partnerships for the good of our state.

Omtvedt Innovation Awards Presented To Chris Calkins, Steven Jones, Rodger Johnson, And Sheila Scheideler, John Owens

John Owens: Speeches and Appearances

It's a great pleasure to welcome you to this very first recognition ceremony for the Omtvedt Innovation Awards. We are present here to honor innovation strengths of the Institute of Agriculture and Natural Resources, and certainly the four faculty members receiving today's awards are greatly deserving of this recognition. Just hearing about their work is gratifying!

Elemental Uptake In Relation To Root Characteristics Of Tall Fescue, Glenn E. Shewmaker, Douglas A. Johnson, Henry F. Mayland, Scott A. Martin, Susie B. Hansen

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

HiMag, an accession of tall fescue (Festuca arundinacea Schreb.), was selected for high magnesium (Mg) concentration in leaves to reduce grass tetany risk to ruminants. However, the mechanism for enhanced Mg uptake in HiMag leaves has not been determined. The objective was to investigate if increased Mg uptake in HiMag could be explained by differences in elemental distribution among plant parts, root characteristics, or organic acid concentrations compared to its parental cultivars, ‘‘Kentucky 31’’ (KY31) and ‘‘Missouri 96’’ (MO96). The study was conducted on a surface-irrigated calcareous Portneuf silt loam (coarse-silty, mixed, mesic, Durinodic Xeric Haplocalcid). Vegetation and soil …

Betaine Improves Growth, But Does Not Induce Whole Body Or Hepatic Palmitate Oxidation In Swine (Sus Scrofa Domestica), Diane Wray-Cahen, Ignacio Fernández-Fígares, Erkki Virtanen, Norman C. Steele, Thomas J. Caperna

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Dietary betaine may reduce carcass fat in growing pigs. We explored the effects of betaine on short-term growth and in vivo and in vitro fatty acid oxidation. Pigs were housed in metabolism crates and fed diets containing either 0% (control), 0.125% or 0.5% betaine at 80% of ad libitum energy intake. Fatty acid oxidation was measured during intravenous infusions of 1-¹³C-palmitate and in hepatocytes incubated in the presence or absence of betaine and carnitine. CO₂ and palmitate isotopic enrichments were determined by mass spectrometry. Pigs consuming 0.125% and 0.5% betaine for at least 9 days had growth …

Rubidium Chloride And Cesium Chloride Sprayed On Maize Plants And Evaluated For Marking Diatraea Grandiosella (Lepidoptera: Crambidae) In Mark–Recapture Dispersal Studies, Jawwad A. Qureshi, Lawrent L. Buschman, James E. Throne, Paul M. Whaley, Sonny B. Ramaswamy

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Experiments were undertaken to determine the potential for using rubidium chloride (RbCl) or cesium chloride (CsCl) to mark southwestern corn borer, Diatraea grandiosella Dyar, for use in applied ecological studies. Maize, Zea mays L., plants were sprayed with aqueous solutions of RbCl or CsCl at rates of 100, 1000, or 10,000 µg/g and inoculated with D. grandiosella neonates. Rubidium and cesium were successfully absorbed and translocated in maize plants. There were only a few minor effects of the treatment on maize or on southwestern corn borers.Rb and Cs were detected in plants, but not in insects, by using Flame …