Life Sciences Commons^™

Biology And Biological Control Of Yellow Starthistle, Linda M. Wilson, Cynthia Jette, John Connett, Joseph Mcaffrey

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

Yellow starthistle (Centaurea solstitialis L.) is an invasive weed introduced from the Mediterranean region. It predominantly infests rangelands in the western United States. This second edition manual on the biological control of yellow starthistle is intended to give weed and land managers guidelines to develop and successfully establish a starthistle biocontrol program.

Factors Related To Body Condition Of Nestling Burrowing Owls In Buffalo Gap National Grassland, South Dakota, Randall L. Griebel, Julie A. Savidge

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

We analyzed the body condition of nestling Burrowing Owls (Athene cunicularia) at Buffalo Gap National Grassland during the summers of 1999 and 2000. In 1999, which had a wet spring, body condition was negatively related to brood size and distance from nest to colony edge. There was no relationship between body condition and brood size during 2000, which had normal precipitation. In 2000, nestlings of early arriving pairs were in better body condition than those that arrived later. The variance in body condition within a brood was not related to brood size.

Evaluation Of Resistance Screening Methods For Sclerotinia Stem Rot Of Soybean And Dry Bean, Linda S. Kull, Tri D. Vuong, Kris S. Powers, Kent M. Eskridge, James R. Steadman, Glen L. Hartman

Department of Plant Pathology: Faculty Publications

Three methods to identify levels of resistance to Sclerotinia sclerotiorum in soybean (Glycine max) and dry bean (Phaseolus vulgaris) were compared using multiple data analyses. The three methods were mycelial plug inoculations of cotyledons, cut stems, and detached leaves. Six S. sclerotiorum isolates of known relative aggressiveness were inoculated on each of three soybean and dry bean cultivars with varied response to S. sclerotiorum. For soybean, all three inoculation methods accurately identified isolate aggressiveness irrespective of cultivar, but identification of susceptible and partially resistant soybean cultivars was influenced by isolate. For dry bean, the cotyledon and cut …

Osmosensitive Taurine Release: Does Taurine Share The Same Efflux Pathway With Chloride And Other Amino Acid Osmolytes?, Rodrigo Franco

School of Veterinary and Biomedical Sciences: Faculty Publications

Swelling subsequent to hyposmotic conditions activates a process of volume regulation present in most cell types. This volume adjustment is accomplished by osmolyte translocation toward the extracellular space to reach a new osmotic equilibrium. Molecules involved in this homeostatic mechanism have been broadly classified into two categories: organic and inorganic osmolytes. Inorganic osmolytes comprise mainly the intracellular ions K⁺ and Cl^–. Cell swelling–induced activation of separate K⁺ and Cl^– channels has been described in most preparations. Organic osmolytes are grouped in three categories: amino acids, polyalcohols, and methylamines. These osmolytes, particularly taurine, are present in …

Role Of Activator Protein-1 In The Down-Regulation Of The Human Cyp2j2 Gene In Hypoxia, Nicole Y. Marden, Eva Fiala-Beer, Shi-Hua Xiang, Michael Murray

School of Veterinary and Biomedical Sciences: Faculty Publications

The cytochrome P450 (CYP) 2J2 arachidonic acid epoxygenase gene was down-regulated at a pre-translational level in human hepatoma-derived HepG2 cells incubated in a hypoxic environment; under these conditions, the expression of c-Jun and c-Fos mRNA and protein was increased. The 5′-upstream region of the CYP2J2 gene was isolated by amplification of a 2341 bp fragment and putative regulatory elements that resembled activator protein-1 (AP-1)-like sequences were identified. From transient transfection analysis, c-Jun was found to strongly activate a CYP2J2–luciferase reporter construct, but co-transfection with plasmids encoding c-Fos or c-Fos-related antigens, Fra-1 and -2, abrogated reporter activity. Using a series …

A Phylogenetic Study Of Cytochrome B561 Proteins, Wim Verelst, Han H. Asard

Department of Biochemistry: Faculty Publications

Background: As an antioxidant and cofactor to numerous metabolic enzymes, ascorbate has an essential role in plants and animals. Cytochromes b561 constitute a class of intrinsic membrane proteins involved in ascorbate regeneration. Despite their importance in ascorbate metabolism, no evolutionary analysis has been presented so far on this newly described protein family. Results: Cytochromes b561 have been identified in a large number of phylogenetically distant species, but are absent in fungi and prokaryotes. Most species contain three or four cytochrome b561 paralogous proteins, and the encoding genes usually have four or five exons. At the protein level, sequence similarities are …

Functional Copper At The Acetyl-Coa Synthase Active Site, Javier Seravalli, Welwel Gu, Annie Tam, Erick Strauss, Stephen P. Cramer, Stephen W. Ragsdale

Department of Biochemistry: Faculty Publications

The bifunctional CO dehydrogenase/acetyl-CoA synthase (CODH/ACS) plays a central role in the Wood–Ljungdahl pathway of autotrophic CO₂ fixation. A recent structure of the Moorella thermoacetica enzyme revealed that the ACS active site contains a [4Fe-4S] cluster bridged to a binuclear Cu-Ni site. Here, biochemical and x-ray absorption spectroscopic (XAS) evidence is presented that the copper ion at the M. thermoacetica ACS active site is essential. Depletion of copper correlates with reduction in ACS activity and in intensity of the ‘‘NiFeC’’ EPR signal without affecting either the activity or the EPR spectroscopic properties associated with CODH. In contrast, Zn content …

The Many Faces Of Vitamin B12: Catalysis By Cobalamin-Dependent Enzymes, Ruma Banerjee, Stephen W. Ragsdale

Department of Biochemistry: Faculty Publications

Vitamin B₁₂ is a complex organometallic cofactor associated with three subfamilies of enzymes: the adenosylcobalamin-dependent isomerases, the methylcobalamin-dependent methyltransferases, and the dehalogenases. Different chemical aspects of the cofactor are exploited during catalysis by the isomerases and the methyltransferases. Thus, the cobalt-carbon bond ruptures homolytically in the isomerases, whereas it is cleaved heterolytically in the methyltransferases. The reaction mechanism of the dehalogenases, the most recently discovered class of B₁₂ enzymes, is poorly understood. Over the past decade our understanding of the reaction mechanisms of B₁₂ enzymes has been greatly enhanced by the availability of large amounts of enzyme …

Impact Of Fire Management On The Ecology Of Collared Lizard (Crotaphytus Collaris) Populations Living On The Ozark Plateau, Jennifer A. Brisson, Jared L. Strasburg, Alan R. Templeton

School of Biological Sciences: Faculty Publications

Eastern collared lizards (Crotaphytus collaris collaris) on the Ozark Plateau of southern Missouri are restricted to islands of rocky glade habitat located throughout the oak–hickory forests of the region. Human mediated suppression of fire negatively impacts collared lizard populations by permitting the overgrowth and consequent disappearance of this glade habitat and also leads to a dense forest understorey that impedes movement of lizards between glades. We present data examining the effects of a fire management regime on collared lizard populations we monitored via mark/recapture from 1998 to 2001. We demonstrate increased glade-to-glade dispersal, colonization of previously unoccupied glades, …

Native Thistles: Expendable Or Integral To Ecosystem Resistance To Invasion?, Svata M. Louda, Tatyana A. Rand

School of Biological Sciences: Faculty Publications

One way of addressing the question of whether some species are expendable is to ask what role, if any, a minor species, even one that seems obnoxious, plays in the functioning of its community. Thistles (Cirsium spp.) are prickly plants native to North America that are numerically minor and are often considered unattractive or undesirable. So, thistles might be considered expendable. Yet, can we assume that such minor, seemingly undesirable species can be elirninated without disrupting important interdependencies or losing key ecological services? Our long-term studies of thistle-insect interactions are beginning to provide evidence that even such species may …

Improving Precision And Reducing Bias In Biological Surveys: Estimating False-Negative Error Rates, Andrew J. Tyre, Brigitte Tenhumberg, Scott A. Field, Darren Niejalke, Kirsten Parris, Hugh P. Possingham

School of Biological Sciences: Faculty Publications

The use of presence/absence data in wildlife management and biological surveys is widespread. There is a growing interest in quantifying the sources of error associated with these data. We show that false-negative errors (failure to record a species when in fact it is present) can have a significant impact on statistical estimation of habitat models using simulated data. Then we introduce an extension of logistic modeling, the zero-inflated binomial (ZIB) model that permits the estimation of the rate of false-negative errors and the correction of estimates of the probability of occurrence for false-negative errors by using repeated visits to the …

Food Supplements Modulate Changes In Leucocyte Numbers In Breeding Male Ground Squirrels, Gwendolyn C. Bachman

School of Biological Sciences: Faculty Publications

Immunosuppression may be an important cost of reproduction in breeding males. It can result from elevated levels of testosterone or stress hormones and may serve to lower the energetic cost of maintaining immune function at a time of high demand. This suggests that greater access to energy resources could reduce immunosuppression as a cost of reproduction, minimizing the trade-off between energetic investment in current reproductive effort and survival. I examined the impact of food availability on immune function by provisioning male Belding’s ground squirrels in the field from the time they emerged from hibernation to the start of breeding. Temporal …

Large-Scale Cultivation Of Acidophilic Hyperthermophiles For Recovery Of Secreted Proteins, Penny Worthington, Paul H. Blum, Francisco Perez-Pomares, Tom Elthon

School of Biological Sciences: Faculty Publications

An electric water heater was modified for large-scale cultivation of aerobic acidophilic hyperthermophiles to enable recovery of secreted proteins. Critical changes included thermostat replacement, redesign of the temperature control circuit, and removal of the cathodic anticorrosion system. These alterations provided accurate temperature and pH control. The bioreactor was used to cultivate selected strains of the archaeon Sulfolobus solfataricus and other species within this genus. Reformulation of a basal salts medium facilitated preparation of large culture volumes and eliminated sterilization-induced precipitation of medium components. Substrate induction of synthesis of the S. solfataricus-secreted alpha-amylase during growth in a defined medium …

Eight Gram-Negative Bacteria Are 10,000 Times More Sensitive To Cationic Detergents Than To Anionic Detergents, Soumitra Rajagopal, Nicole Eis, Kenneth Nickerson

Kenneth Nickerson Papers

In liquid culture, eight typical Gram-negative bacteria were ca. 10,000-fold more sensitive to cationic detergents than to the anionic detergent sodium dodecyl sulfate. Cetyltrimethylammonium bromide (CTAB) was inhibitory at concentrations ranging from 0.0006% to 0.01%. Four pseudomonads able to form biofilms were ca. 1000-fold more resistant to CTAB on Luria–Bertani agar plates than they were in liquid culture. A lasI mutant of Pseudomonas aeruginosa was only able to tolerate 0.1% CTAB on Luria–Bertani agar plates but could tolerate 5% CTAB when supplemented with homoserine lactone containing culture supernatants.

En culture liquide, huit bactéries Gram négatif typiques étaient ca. 10,000 fois …

Nontarget Effects—The Achilles’ Heel Of Biological Control? Retrospective Analyses To Reduce Risk Associated With Biocontrol Introductions, Svata M. Louda, R. W. Pemberton, M. T. Johnson, P. A. Follett

Papers in Ecology

Controversy exists over ecological risks in classical biological control. We reviewed 10 projects with quantitative data on nontarget effects. Ten patterns emerged: (a) Relatives of the pest are most likely to be attacked; (b) host-specificity testing defines physiological host range, but not ecological range; (c) prediction of ecological consequences requires population data; (d) level of impact varied, often in relation to environmental conditions; (e) information on magnitude of nontarget impact is sparse; ( f ) attack on rare native species can accelerate their decline; (g) nontarget effects can be indirect; (h) agents disperse from agroecosystems; (i) whole assemblages of species …

A New Species Of Laelapine Mite (Acari: Parasitiformes: Laelapidae) Associated With Proechimys Dimidiatus In The Atlantic Forests Of Brazil, Donald Gettinger, Helena Godoy Bergallo

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Tur megistoproctus, a new species of Laelapinae, is described from the pelage of the echimyid rodent Proechimys dimidiatus from the Atlantic forests of Ilha Grande, south of Rio de Janeiro. Measurements and illustrations are included for females and males. Another laelapine mite species, Tur turki Fonseca, co-occurred with T.megistoproctus in our studies and was recorded from the same host individuals and localities. These 2 laelapine mite species appear to be exclusively associated with a complex of echimyid rodent species (subgenus Trinomys) in the Atlantic forests of southeastern Brazil.

A New Species Of Neotropical Laelapine Mite (Acari: Parasitiformes, Laelapidae) From The Marsupial Monodelphis Americana, Donald Gettinger, Fernanda Martins-Hatano

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Androlaelaps ilhacardosoi, a new species of Laelapinae, is described from the pelage of a 3-lined marsupial, Monodelphis americana, collected on Ilha Cardoso, São Paulo State, Brazil. The description is based on the female, and the systematics of laelapine mites associated with neotropical marsupials is discussed.

Phylogenetic Analysis Of The Metastrongyloidea (Nematoda: Strongylida) Inferred From Ribosomal Rna Gene Sequences, Ramon A. Carreno, Steven A. Nadler

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Phylogenetic relationships among nematodes of the strongylid superfamily Metastrongyloidea were analyzed using partial sequences from the large-subunit ribosomal RNA (LSU rRNA) and small-subunit ribosomal RNA (SSU rRNA) genes. Regions of nuclear ribosomal DNA (rDNA) were amplified by polymerase chain reaction, directly sequenced, aligned, and phylogenies inferred using maximum parsimony. Phylogenetic hypotheses inferred from the SSU rRNA gene supported the monophyly of representative taxa from each of the 7 currently accepted metastrongyloid families. Metastrongyloid taxa formed the sister group to representative trichostrongyloid sequences based on SSU data. Sequences from either the SSU or LSU RNA regions alone provided poor resolution for …

Testis Size Increases With Colony Size In Cliff Swallows, Charles R. Brown, Mary Bomberger Brown

School of Biological Sciences: Faculty Publications

By using a sample of more than 800 male cliff swallows (Petrochelidon pyrrhonota) that died during a rare climatic event in our Nebraska study area in 1996, we investigated how testis size was related to body size, age, parasite load, a bird’s past colony-size history, and spleen size. Testis volume in-creased with body size. After correcting for body size, testis volume was lowest for birds age 1 and 2 years but did not vary with age for males 3 years old or more. Birds occupying parasite-free (fumigated) colonies had significantly larger testes than did birds at non-fumigated sites. …

The Safety Of Genetically Modified Foods Produced Through Biotechnology, Robert M. Hollingworth, Leonard F. Bjeldanes, Michael Bolger, Ian Kimber, Barbara Jean Meade, Steve L. Taylor, Kendall B. Wallace

Department of Food Science and Technology: Faculty Publications

The Society of Toxicology (SOT) is committed to protecting and enhancing human, animal, and environmental health through the sound application of the fundamental principles of the science of toxicology. It is with this goal in mind that the SOT defines here its current consensus position on the safety of foods produced through biotechnology (genetic engineering). These products are commonly termed genetically modified foods, but this is misleading, since conventional methods of microbial, crop, and animal improvement also produce genetic modifications and these are not addressed here.
The available scientific evidence indicates that the potential adverse health effects arising from biotechnology-derived …

Genome Diversification In Phylogenetic Lineages I And Ii Of Listeria Monocytogenes: Identification Of Segments Unique To Lineage Ii Populations, Chaomei Zhang, Min Zhang, Jingliang Ju, Joseph Nietfeldt, John Wise, Phillip M. Terry, Michael Olson, Stephen D. Kachman, Martin Wiedmann, Mansour Samadpour, Andrew K. Benson

Department of Food Science and Technology: Faculty Publications

Thirteen different serotypes of Listeria monocytogenes can be distinguished on the basis of variation in somatic and flagellar antigens. Although the known virulence genes are present in all serotypes, greater than 90% of human cases of listeriosis are caused by serotypes 1/2a, 1/2b, and 4b and nearly all outbreaks of food-borne listeriosis have been caused by serotype 4b strains. Phylogenetic analysis of these three common clinical serotypes places them into two different lineages, with serotypes 1/2b and 4b belonging to lineage I and 1/2a belonging to lineage II. To begin examining evolution of the genome in these serotypes, DNA microarray …

Wagonhammer Education Center Groundbreaking, John Owens

John Owens: Speeches and Appearances

Last year when I had the opportunity to speak at the 2002 Gudmundsen Sandhills Laboratory Open House I noted the tremendous gift Pete and Abbie Gudmundsen gave the university, the people who live throughout their beloved Sandhills, and, indeed, the entire state of Nebraska when they donated their almost 13,000 acre ranch, the Rafter C, to the University of Nebraska Foundation back in 1978.

Coccidia In The Mammary Glands Of Shrews (Order: Insectivora), Donald W. Duszynski, William C. Marquardt

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Three of 6 female long-clawed shrews, Sorex unguiculatus Dobson, 1890, collected on the island of Hokkaido, Japan, were found to have unsporulated oocysts and sexual stages (both macro- and microgamonts) in varying stages of development of an unidentified coccidium in both lactating and non lactating mammary glands. Gamonts developed in the alveoli of the mammary glands, and oocysts were found in the lactiferous ducts and in pools of milk. Mature macrogamonts were 11.9 × 15.2 μm (10-14 × 14-20 μm), whereas completely developed microgamonts with many gametes were 14.8 × 16.8 μm (10-18 × 13-20 μm). Oocysts in tissue sections …

Eimeria Species From Cryptotis Shrews (Insectivora: Soricidae) With Description Of A New Species, Donald W. Duszynski, Ralph P. Eckerlin, Timothy J. Mccarthy

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Fresh fecal samples from 12 shrews, 10 Cryptotis goodwini Jackson, 1933, and 2 Cryptotis merriami Thomas, 1898, were collected between December 1994 and May 1998; 11 (92%) were positive for eimeriid coccidia, including 8 of 8 C. goodwini and 2 of 2 C. merriami from Honduras and 1 of 2 C. goodwini from Guatemala. Two Eimeria species were found: 1 is consistent with the description of Eimeria whitakeri Upton and McAllister, 1991, and 1 is described in this study as new. Sporulated oocysts of the new species are subspheroidal, 16.8 × 15.7 (14–20 × 15–19) μm, with a length–width (L/W) …

Experimental Mycobacteriosis In Striped Bass Morone Saxatilis, D. T. Gauthier, M. W. Rhodes, W. K. Vogelbein, H. Kator, C. A. Ottinger

Biological Sciences Faculty Publications

Striped bass Morone saxatilis were infected intraperitoneally with approximately 10⁵ Mycobacterium marinum, M. shottsii sp. nov., or M. gordonae. Infected fish were maintained in a flow-through freshwater system at 18 to 21°C, and were examined histologically and bacteriologically at 2, 4, 6, 8, 17, 26, 36 and 45 wk post-infection (p.i.). M. marinum caused acute peritonitis, followed by extensive granuloma development in the mesenteries, spleen and anterior kidney. Granulomas in these tissues underwent a temporal progression of distinct morphological stages, culminating in well-circumscribed lesions surrounded by normal or healing tissue. Mycobacteria were cultured in high numbers from …

Enhancement Of Disease And Pathology By Synergy Of Trichuris Suis And Campylobacter Jejuni In The Colon Of Immunologically Naive Swine, Linda S. Mansfield, David T. Gauthier, Sheila R. Abner, Kathryn M. Jones, Stacey R. Wilder, Joseph F. Urban

Biological Sciences Faculty Publications

Campylobacter jejuni, a leading cause of bacterial gastroenteritis, has different age distribution and disease expression in developing and developed countries, which may be due to the endemnicity of infection and the age of acquisition of immunity. Differences in disease expression are not solely dependent on the C jejuni strain or virulence attributes. Another modulating factor in developing countries may be endemic nematode infections such as Trichuris, which drive type 2 cytokine responses and down-regulate type I immune responses. In this study, three-day-old germfree pigs given dual infections with Trichuris suis and C jejuni had more frequent, more severe …

Chemical Composition Of Some Components Of The Arrestment Pheromone Of The Black-Legged Tick, Ixodes Scapularis (Acari : Ixodidae) And Their Use In Tick Control, Daniel E. Sonenshine, Trevor Adams, Sandra A. Allan, John Mclaughlin, Francis X. Webster

Biological Sciences Faculty Publications

Chemical analysis (high-performance liquid chromatography) and bioassay demonstrated the presence of compounds that seem to be components of the Ixodes scapularis arrestment pheromone. Only two purines, guanine and xanthine, were found in acidified saline extracts made from cast skins after molting of fed nymphs, fed larvae, and fecal/excretory exudates deposited by unfed adults on substrates in their environment. The ratio of guanine to xanthine was 10.6:1 in an extract from the nymphal skins versus 0.95:1 in an extract from the larval skins. Guanine, xanthine, and traces of a third purine, tentatively identified as 8-azaguanine, were found in extracts made from …

Dna Sequence Of Melanocortin 1-Receptor Gene In Coturnix Japonica: Correlation With Three E Locus Alleles—E,E+, And Erh, Rupali Ugrankar, Kim Cheng, Ronald Okimoto

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

The melanocortin 1-receptor (MC1-R) gene plays a key role in the expression of fur and feather color in mammals and birds by regulating the distribution of two melanin pigments: eumelanin (black/brown) and pheomelanin (red/yellow). MC1-R corresponds to the classical Extension (E) locus in mice, pigs, dogs, horses, and chickens. Three E locus alleles, the wild-type (e+), brown (E), and redhead (erh) have been identified in Japanese quail (Coturnix japonica). To determine if the quail E locus phenotypes were due to variation in the MC1-R gene, the coding region of the MC1-R gene was PCR amplified and DNA sequenced using genomic …

Electrofusion Of Saccharomyces Cerevisiae Auxotrophic Mutants Of Identical Mating Type Using A Laboratory-Made System, Gökhan Coral, Ömer Çolak, M. Ni̇sa Ünaldi, Burhan Arikan

Turkish Journal of Biology

Yeast protoplasts from haploid auxotroph strains DC6 (MAT\alpha) and FY73 (MAT\alpha) were exposed to an inhomogeneous alternating field (AC 200 V/cm). Due to the dielectrophoretic aggregation two or more cells with close membrane contact were formed between the two electrodes. The effects of different DC pulses were investigated to determine critical fusogenic pulse strength. In the results, the maximum fusant cells were obtained only when 8 kV field strengths were applied. These findings showed that the optimum fusogenic pulse strength for yeast protoplasts is 8 kV/cm under our experimental conditions. After fusion, the DNA contents of both hybrid and individual …

Extremely Halophilic Bacterial Communities In Şereflikoçhisar Salt Lake In Turkey, Meral Bi̇rbi̇r, Cenk Sesal

Turkish Journal of Biology

Şereflikoçhisar Lake is the largest salt lake in central Turkey. This lake is a major source of solar salt for food, hide and other industries locally. Due to the economic importance of salt obtained from this lake, a microbial survey has been conducted. Six salt and three brine samples were obtained from the lake for physico-chemical and microbiological analyses. Physico-chemical analysis showed that the salts and brines contain sufficient ions and hardness to support extremely halophilic bacteria. The salt collected from the lake contained 10^4-10^6 colony-forming units of extremely halophilic bacteria per gram and brine taken from the lake contained …