Digital Commons Network^™

Effect Of Starch Encapsulation And Temperature On Volatilization Of Atrazine And Alachlor, Brian J. Wienhold, Ali M. Sadeghi, Timothy J. Gish

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

Volatilization of agricultural chemicals is one process whereby chemicals may enter into parts of the environment where they were not intended. Starch encapsulation of pesticides has been proposed as a way of modifying pesticide behavior in the soil environment. This study was conducted to assess how starch encapsulation and temperature affect volatilization of atrazine [6-chloro-N-ethyI-N’-(1-methylethyl) - 1, 3, 5-triazine-2,4-diamine] and alachlor [2-chloro-N-(2,6- diethylphenyl)-N-(methoxymethyl)acetamide]. Volatilization measured using agroecosystem chambers as model systems. Herbicides were applied at rates of 1.7 kg ha^‒1 -for atrazine and 2.8 kg ha^‒1 for alachlor, as either a commercial formulation or …

Impacts, Tillites, And The Breakup Of Gondwanaland, Verne R. Oberbeck, John R. Marshall, Hans Aggarwal

United States National Aeronautics and Space Administration: Publications

Mathematical analysis demonstrates that substantial impact crater deposits should have been produced during the last 2 Gy of Earth's history. Textures of impact deposits are shown to resemble textures of tillites and diamictites of Precambrian and younger ages. The calculated thickness distribution for impact crater deposits produced during 2 Gy is similar to that of tillites and diamictites ≤2 Ga. We suggest, therefore, that some tillites/diamictites could be of impact origin. Extensive tillite/diamictite deposits predated continental flood basalts on the interior of Gondwa- naland. Significantly, other investigators have already associated impact cratering with flood basalt volcanism and continental rifting. Thus, …

Economic Injury Levels For Western Bean Cutworm, Loxagrotis Albicosta (Smith) (Lepidoptera: Noctuidae), Eggs And Larvae In Field Corn, Larry L. Appel, Robert J. Wright, John B. Campbell

Department of Entomology: Faculty Publications

Yield losses caused by different densities of western bean cutworm, [Loxagrotis albicosta (Smith)], egg masses and young larvae in field corn [Zea mays(L.), Pioneer 3475] were studied in replicated field cages in Perkins County, Nebraska, during 1989 and 1990. Treatments consisted of four egg masses per plant, one egg mass per plant, ten young larvae per plant, three young larvae per plant and an uninfested caged check. Infestations were timed to correspond with the natural occurrence of western bean cutworms each year. Larval density at dent stage and total grain yield were measured. Linear regression equations were …

The Conservation Reserve Program And Grassland Birds, Douglas H. Johnson, Michael D. Schwartz

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

Several bird species that breed in the temperate grasslands of North America, many of which winter in the Neotropics, declined in abundance during the past quarter century. The Lark Bunting and Grasshopper Sparrow, as examples, declined by about half during that period, as indexed by the U.S. Fish and Wildlife Service's Breeding Bird Survey. Populations of other grassland species have also diminished steadily, if not as spectacularly.

Book Review: The Baculovirus Expression System: A Laboratory Guide (1992) King, L. A. & Possee, R. D., David D. Dunigan

Nebraska Center for Virology: Faculty Publications

The power of molecular biology is unleashed with the ability to clone and sequence genes, and then express these genes in heterologous systems. This sets the stage for the full analysis of proteins that are otherwise difficult to isolate and/or purify, especially when present at very low copy number per cell or when isolated from relatively precious materials. Overexpression of protein is now possible in a number of systems including prokaryotes (e.g., E. coli) and various eukaryotes (yeast, insects, and plants). The issue then becomes, which system (1) most closely reflects the homologous expression with respect to posttranslational modifications, …

A Polymerase Chain Reaction Method For Identification Of Five Major Meloidogyne Species, Thomas O. Powers, T. S. Harris

Department of Plant Pathology: Faculty Publications

A polymerase chain reaction (PCR) method for discriminating Meloidogyne incognita, M. arenaria, M. javanica, M. hapla, and M. chitwoodi was developed. Single juveniles were ruptured in a drop of water and added directly to a PCR reaction mixture in a microcentrifuge tube. Primer annealing sites were located in the 3' portion of the mitochondrial gene coding for cytochrome oxidase subunit II and in the 16S rRNA gene. Following PCR amplification, fragments of three sizes were detected. The M. incognita and M. javanica reactions produced a 1.7-kb fragment; the M. arenaria reaction, a 1.1-kb fragment; and the …

Detection Of Serum Antibody Responses In Cattle With Natural Or Experimental Neospora Infections, Patricia Conrad, Karen Sverlow, Mark Anderson, Joan Rowe, Robert Bondurant, Gwen Tuter, Richard Breitmeyer, California Department Of Food And Agriculture, Animal Health Branch, Mark Thurmond, Alex Ardans, J. P. Dubey, Gerarld Duhamel, Bradd Barr

School of Veterinary and Biomedical Sciences: Faculty Publications

Parasite-specific antibody responses were detected using an indirect fluorescent antibody (IFA) test in cattle that were naturally or experimentally infected with Neospora parasites. The test was developed using Neospora tachyzoites isolated from an aborted bovine fetus and grown in bovine cell cultures (isolate BPA1). In all cases, infections were confirmed by the identification of Neospora tachyzoites and/or bradyzoite cysts in fetal or calf tissues using an immunoperoxidase test procedure. Fifty-five naturally infected cows that aborted Neospora-infected fetuses had titers of 320-5,120 at the time of abortion. The titer of 6 cows that were serologically monitored over a prolonged period decreased …

Dependence Of 3 Nebraska Sandhills Warm-Season Grasses On Vesicular-Arbuscular Mycorrhizae, John J. Brejda, D. H. Yocom, Lowell E. Moser, Steven S. Waller

Department of Agronomy and Horticulture: Faculty Publications

Vesicular-arbuscular mycorrhizae (VAM) are rare or absent in actively eroding soils of the Sandhills. The objective of this study was to determine if 3 major Sandhills warm-season grasses used in reseeding eroded Sandhills sites are highly mycorrhizal dependent, and evaluate the response of VAM at different phosphorus (P) levels. In 2 greenhouse experiments, sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.], switchgrass, (Panicum virgatum L.), and prairie sandreed [Calamovilfa longifolio (Hook) Scribn.] were grown in steam-sterilized sand in pots and inoculated with either indigenous Sandhills VAM, Glomus deserticola, or noninoculated. In the second experiment, VAM inoculated …

Breeding Systems For Cross-Pollinated Perennial Grasses, K. P. Vogel, Jeffrey F. Pedersen

Department of Agronomy and Horticulture: Faculty Publications

I. Introduction

II. Reproductive and Breeding Characteristics

III. Breeding Systems

A. Ecotype Selection

B. Recurrent, RestricteclPhenotypic Selection

C. Half-sib Progeny Test

D. Between and Within Family Selection

E. Recurrent Multistep Family Selection

IV. Gains From Selection

A. Time Interval per Cycle

B. Potential Gain per Cycle .

C. Potential Inbreeding per Cycle

V. Polycrossing

VI. Hybrid Cultivars

VII. Conclusions

Literature Cited

Drying Rate Constants For Yellow Dent Corn As Affected By Fatty Acid Ester Treatments, Curtis L. Weller, J. M. Bunn

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Ethyl oleate and ethyl stearate solutions at various concentrations were used to treat corn samples prior to drying.

Modification Of Physical And Barrier Properties Of Edible Wheat Gluten-Based Films, Aristippos Gennadios, Curtis L. Weller, Robert F. Testin

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Edible films were produced from wheat gluten-based film-forming solutions. One film was produced as a control. Other types came from subjecting control films to three different soaking treatments. Three additional films were also produced by modifying the control film-forming solution. For all films, selected physical properties and permeability to water vapor and oxygen were measured. Comparisons indicated possible ways to improve the control film. All films were good oxygen barriers but limited water vapor barriers. Films containing hydrolyzed keratin had lower oxygen permeability (83%) and lower water vapor permeability (23%). Films containing mineral oil had lower water vapor permeability (25%). …

Shared Thematic Elements In Photochemical Reaction Centers, John H. Golbeck

Department of Biochemistry: Faculty Publications

The structural, functional, and evolutionary relationships between photosystem II and the purple nonsulfur bacterial reaction center have been recognized for several years. These can be classified as "quinone type" (type I) photosystems because the terminal electron acceptor is a mobile quinone molecule. The analogous relationship between photosystem I and the green sulfur bacterial (and heliobacterial) reaction centers has only recently become dear. These can be dcassified as "iron-sulfur type" (type I) photosystems because the terminal electron acceptor consists of one or more bound iron-sulfur clusters. At a fundamental level, the quinone type and ironsulfur type reaction centers share a common …

Mutational Analysis Of The Structure And Biogenesis Of The Photosystem I Reaction Center In The Cyanobacterium Synechocystis Sp. Pcc 6803, Lawrence B. Smart, Patrick V. Warren, John H. Golbeck, Lee Mcintosh

Department of Biochemistry: Faculty Publications

We have utilized the unicellular cyanobacterium Synechocystis sp. PCC 6803 to incorporate site-directed amino acid substitutions into the photosystemn I (PSI) reactioncenter protein PsaB. A cysteine residue (position 565 of PsaB) proposed to serve as a ligand to the [4Fe-4S] center F_x was changed to serine, histidine, and aspartate. These three mutants- C565S, C565H, and C565D-all exhibited greatly reduced accumulation of PSI reaction-center proteins and failed to grow autotrophically, indicating that this cysteine most likely does coordinate F_x, which is crucial for PSI biogenesis. Interestingly, the strain C565S accumulated significantly more PSI than the other two cysteine …

Exopeptidase Catalyzed Site-Specific Bonding Of Supports, Labels And Bioactive Agents To Proteins, Fred W. Wagner, Thomas R. Coolidge, Sheldon M. Schuster, Jay Stout, Dwane E. Wylie, Klaus Breddam, William Lewis

Department of Biochemistry: Faculty Publications

An auxiliary substance such as a label, support, or bioactive agent is attached to a protein at a site that is remote from the active site of the protein by the use of exopeptidase and a nucleophile which is an amino acid, amino acid derivative, amine or alcohol. In one embodiment, the nucleophile is attached to the carboxy terminus of a protein by catalysis with exopeptidase to form an adduct and then the adduct or its combination with a linker arm is bound to the auxiliary substance. In another embodiment, the auxiliary substance or its combination with a linker arm …

The Presequence Of Euglena Lhcpii, A Cytoplasmically Synthesized Chloroplast Protein, Contains A Functional Endoplasmic Reticulum-Targeting Domain, Ram Kishore, Umesh S. Muchhal, Steven D. Schwartzbach

School of Biological Sciences: Faculty Publications

The precursor to the Euglena light-harvesting chlorophyll a/b-binding protein of photosystem II (pLHCPII) is unique; it is a polyprotein, synthesized on membrane-bound ribosomes and transported to the Golgi apparatus prior to chloroplast localization. A cDNA corresponding to the 5' end of LHCPII mRNA has been isolated and sequenced. The deduced amino acid sequence of this cDNA indicates that Euglena pLHCPII contains a 141-amino acid N-terminal extension. The N-terminal extension contains three hydrophobic domains and a potential signal peptidase cleavage site at amino acid 35. Cotranslational processing by canine microsomes removed approximately 35 amino acids from an in vitro synthesized …

The Functional Analysis Of Nonsense Suppressors Derived From In Vitro Engineered Saccharomyces Cerevisiae TrnaTrp Genes, Audrey L. Atkin, M. A. Riazia, C. L. Greer, K. L. Roye, J. B. Bell

School of Biological Sciences: Faculty Publications

Nonsense suppressors derived from Saccharomyces cerevisiae tRNA^Trp genes have not been identified by classical genetic screens, although one can construct efficient amber (am) suppressors from them by making the appropriate anticodon mutation in vitro. Herein, a series of in vitro constructed putative suppressor genes was produced to test if pre-tRNA^Trp processing difficulties could help to explain the lack of classical tRNA^Trp-based suppressors. It is clear that inefficient processing of in-trons from precursor tRNA^Trp, or inaccurate overall processing, may explain why some of these constructs fail to promote nonsense suppression in vivo. However, deficient processing …

Arabidopsis Glabrous1 Gene Requires Downstream Sequences For Function, John C. Larkin, David G. Oppenheimer, Susan Pollock, M. David Marks

School of Biological Sciences: Faculty Publications

The Arabidopsis GLABROUSl (GL1) gene is a myb gene homolog required for the initiation of trichome development. In situ hybridiration revealed that the highest levels of GL1 transcripts were present in developing trichomes. In contrast, previous work had shown that putative promoter sequences from the 5‘ noncoding region of the GL1 gene directed the expression of a β-glucuronidase (GUS) reporter gene only in stipules. Deletion analysis of the 3’ noncoding region of GL1 has identified an enhancer that is essential for GL1 function. Sequences fmm the region containing the enhancer, in conjunction with GL1 upstream sequences, direct the expression of …

Do Worm Lizards Occur In Nebraska?, Louis A. Somma

Papers in Herpetology

Amphisbaenids, or worm lizards, are a small enigmatic suborder of reptiles (containing 4 families; ca. 140 species) within the order Squamata, which include~ the more speciose lizards and snakes (Gans 1986). The name amphisbaenia is derived from the mythical Amphisbaena (Topsell 1608; Aldrovandi 1640), a two-headed beast (one head at each end), whose fantastical description may have been based, in part, upon actual observations of living worm lizards (Druce 1910). While most are limbless and worm-like in appearance, members of the family Bipedidae (containing the single genus Bipes) have two forelimbs located close to the head. This trait, and …

How Does Variation In Plant Resources Affect Herbivore Dynamics?: Review Of Hunter Et Al., Effects Of Resource Distribution On Animal-Plant Interactions, Svata M. Louda

Svata M. Louda Publications

The book by Hunter et al. has two aims. The first is to focus more attention on the role of variation in resources, specifically plant resources, in the dynamics of herbivorous animals. The emphasis on plant variability in herbivore performance and dynamics, rather than on average patterns of plant resource availability, is timely. Emphasis to date has been on general patterns of resource use. However, knowledge of variation is required to predict outcomes of both ecological processes and evolutionary changes with environmental modification. Thus, I expect this book will be considered an important step on the road to such understanding. …

Effects Of Response Strategy And Retention Interval On Performance Of Clark’S Nutcrackers In A Radial Maze Analogue, Deborah J. Olson, Alan C. Kamil, Russell P. Balda

Papers in Behavior in Biological Sciences

Two groups of Clark’s nutcrackers (Nucifraga columbiana) were trained to use either a stay or shift response strategy in a radial maze analogue. Each trial had a preretention stage, a retention interval, and a postretention test. In Experiment 1, acquisition with a 5-min retention interval was studied. Response strategy did not affect the rate at which the task was learned. Performance following longer retention intervals was tested in Experiments 2-4. Changes in retention intervals were presented in trial blocks of increasing duration in Experiment 2 and were randomly presented between trials in Experiment 3. Experiment 4 extended the …

Meristic And Organogenetic Variation In Ruppia Occidentalis And R. Maritima, Robert B. Kaul

School of Biological Sciences: Faculty Publications

Floral meristic and organogenetic variation was sampled in Ruppia occidentalis from an alkaline lake of the Nebraska Sandhills and in Ruppia maritima var. rostrata from a saline, non-Sandhills lake nearby. The androecium is meristically stable, always having two stamens, but the gynoecium is not. Seventy-two percent of the flowers of R. maritima had four carpels and the others had three, and in 80% of inflorescences the two flowers had the same number. In about one-third of inflorescences having dissimilar carpel numbers, the four-carpellate flower was uppermost. The number of carpels in each flower of R. occidentalis ranged from four to …

Spiculopteragia Spiculoptera And S. Asymmetrica (Nematoda: Trichostrongyloidea) From Red Deer (Cervus Elaphus) In Texas, Lora G. Rickard, Eric P. Hoberg, Nancy M. Allen, Gary L. Zimmerman, Thomas M. Craig

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Specimens of Spiculopteragia spiculoptera and S. asymmetrica were recovered from the abomasa of five of ten naturally infected red deer (Cervus elaphus) in Texas (USA). Female specimens of Spiculopteragia were present in all five animals. Male specimens of S. spiculoptera and S. asymmetrica were present in one of five and three of five red deer, respectively. Spiculopteragia spiculoptera has not previously been recognized in the United States and the present report constitutes the first records of Spiculopteragia spp. in red deer from North America. It is likely that species of Spiculopteragia have been introduced to North America with …

Enteric Coccidia (Apicomplexa) In The Small Intestine Of The Northern Spotted Owl (Strix Occidentalis Caurina), Eric P. Hoberg, R. J. Cawthorn, O. R. Hedstrom

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Sporulated oocysts (mean dimensions = 13.0 x 10.8 μm) and sporocysts (11.3 x 5.5 μm) of a coccidian resembling Frenkelia sp. or Sarcocystis sp. were present in the lamina propria of the small intestine of a naturally-infected northern spotted owl (Strix occidentalis caurina) collected near Medford, Oregon, USA. Dimensions of these oocysts and sporocysts appear to be considerably smaller than those from other sarcocystid species with avian definitive hosts. Additionally, numerous developmental stages and unsporulated oocysts (mean dimensions 22.8 x 17.8 μm) of a possible species of Isospora also were observed in the intestinal epithelium. This constitutes the …

Book Review Of Parascript: Parasites And The Language Of Evolution By D. R. Brooks And D. A. Mclennan, Smithsonian Institution Press, Washington, D.C., 1993., Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Review of Parascript: Parasites and the Language of Evolution by Daniel R. Brooks and Deborah A. McLennan, with bibliographical references.

A Model Of Cell Damage In Space Flight, Robert Katz, F. A. Cucinotta, J. W. Wilson, J. L. Shinn, Duc M. Ngo

Robert Katz Publications

Cell damage by high LET radiations has been described by a phenomenological model (track theory) for 20 years and more. Molecules of biological significance (dry enzymes and viruses) act as 1 hit detectors. Recent additions to the class of I-hit detectors are E. Coli B, and the creation of both single and double strand breaks in SV-40 virus in EO buffer, where indirect effects predominate. The response of cells (survival, transformation, chromosome aberration) to these radiations is typically described by a 4-parameter model whose numerical values are determined by fitting the equations of the theory to experimental data at high …

Telomere Processing In Euplotes, Joris Robert Vermeesch, Dewight Williams, Carolyn M. Price

Department of Chemistry: Faculty Publications

In Euplotes crassus millions of telomeres are synthesized during the sexual phase of the life cycle. Since these newly synthesized telomeres are longer than normal macronuclear telomeres, they must be trimmed to the mature size. We have examined the timing and mechanism of this trimming step. We have shown that a sudden decrease in telomere length takes place at a specific time during macronuclear development. The decrease in telomere length is not caused by incomplete replication of the most terminal DNA sequences; rather it is the result of an active processing event that occurs independently of DNA replication. The developmentally …

Preparation Of Functionalized Polymers Utilizing A Soluble Highly Reactive Form Of Calcium, Reuben D. Rieke

Department of Chemistry: Faculty Publications

Calcium-substituted polymeric reagents are provided. These reagents can be prepared via the oxidative addition of a soluble highly reactive calcium species to organic and inorganic polymers containing alkyl, aryl, or alkylaryl pendent groups substituted with halide atoms, cyanide molecules, 1,3-dienes, or any conjugated poly unsaturated system. Preferably, the polymer is a cross linked p-bromopolystyrene, p-chloropolystyrene, p-fluoropolystyrene, or chloromethylated polystyrene. Preferably, the soluble highly reactive calcium species is prepared from the reduction of Ca(II) salts with an alkali metal arene, such as lithium biphenylide. These calcium-substituted polymeric reagents react with a variety of electrophiles to yield functionalized polymers. Reaction with Cu(I) …

Molecular Approaches For Control Of Tomato Bushy Stunt Virus, H. B. Scholthof, M. Borja, Thomas Jack Morris, A. O. Jackson

School of Biological Sciences: Faculty Publications

I N this overview strategies are discussed that are currently being tested in our laboratory in an effort to engineer resistance against tomato bushy stunt virus (TBSV) in plants. TBSV is chosen as a model-system since this is an economically important RNA virus that is well characterized at the molecular level and the virus has some interesting and potentially useful features that can be exploited to produce resistant plants. Moreover, we anticipate that the information derived from our studies with TBSV will be applicable in developing resistance to other plant viruses. Some approaches that we are attempting to apply to …

Charles Eric "Chuck" Dawson, 1922-1993 [In Memoriam], Robin M. Overstreet, Stuart G. Poss

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Obituary of Charles Eric "Chuck" Dawson, 1922-1993, American marine ichthyologist.

Preserving Natural Science Collections: Chronicle Of Our Environmental Heritage, W. Donald Duckworth, Hugh H. Genoways, Carolyn L. Rose

University of Nebraska State Museum: Mammalogy Papers

This report recommends action in the areas outlined below. Strategies for implementation of each recommendation are presented in chapter three, "Meeting the Challenge: Recommendations and Strategies."

Stewardship of collections

Public awareness

Staffing, education, and training

Technology transfer

Conservation research

Guidelines and standards of practice