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2002

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Articles 2521 - 2550 of 2980

Full-Text Articles in Life Sciences

‘Neuroecologists’ Are Not Made Of Straw, Robert Hampton, Susan Healy, Sara Shettleworth, Alan C. Kamil Jan 2002

‘Neuroecologists’ Are Not Made Of Straw, Robert Hampton, Susan Healy, Sara Shettleworth, Alan C. Kamil

School of Biological Sciences: Faculty Publications

In the October issue of Trends in Cognitive Sciences, Bolhuis and Macphail criticized the functional/evolutionary approach to the neural mechanisms of learning and memory, and concluded that the approach is ‘often misleading and might provide us with the wrong answers’ [1]. Their critique touches on a number of interesting issues, and provides a useful prompt to examine the role of an adaptationist approach to the study of cognition. In their effort to stimulate discussion, however, Bolhuis and Macphail have overstated positions they attribute to ‘neuroecologists’.

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Life History Response Of Mediterranean Fruit Flies To Dietary Restriction, James R. Carey, Pablo Liedo, Lawrence G. Harshman, Ying Zhang, Hans-Georg Müller, Linda Partridge, Jane-Ling Wang Jan 2002

Life History Response Of Mediterranean Fruit Flies To Dietary Restriction, James R. Carey, Pablo Liedo, Lawrence G. Harshman, Ying Zhang, Hans-Georg Müller, Linda Partridge, Jane-Ling Wang

Lawrence G. Harshman Publications

The purpose of this study was to investigate medfly longevity and reproduction across a broad spectrum of diet restriction using a protocol similar to those applied in most rodent studies. Age-specific reproduction and age of death were monitored for 1,200 adult males and 1,200 females, each individually maintained on one of 12 diets from ad libitum to 30% of ad libitum. Diet was provided in a fixed volume of solution that was fully consumed each day, ensuring control of total nutrient consumption for every fly. Contrary to expectation and precedence, increased longevity was not observed at any level of …

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Ecology And Host Specificity Of Laelapine Mites (Acari: Laelapidae) Of Small Mammals In An Atlantic Forest Area Of Brazil, Fernanda Martins-Hatano, Donald Gettinger, Helena G. Bergallo Jan 2002

Ecology And Host Specificity Of Laelapine Mites (Acari: Laelapidae) Of Small Mammals In An Atlantic Forest Area Of Brazil, Fernanda Martins-Hatano, Donald Gettinger, Helena G. Bergallo

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Mesostigmaticm ites of the Laelapinae Berlese, 1892 (Acari:Laelapidae) are nidicolous arthropods that commonly occur in the fur of Neotropical small mammmals. In this 2-yr study, the laelapine acarofauna associated with the small mammal community in an area of Atlantic forest on Ilha Grande, Rio de Janeiro State, was examined, including observations on patterns of host specificity, mite dispersal, ecology, and food habits. A total of 1,347 laelapines was sampled from the pelage of 6 species of small mammals( Marmosops incanus, Nectomyss quamipes, Oryzomys russatus, Rhipidomys n. sp., Oxymycterus dasytrichus, and Trinomys dimidiatus), all of which occurred exclusively in …

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Phylogenetic Positions Of The Bothitrematidae And Neocalceostomatidae (Monopisthocotylean Monogeneans) Inferred From 28s Rdna Sequences, Jean-Lou Justine, Richard Jovelin, Lassâd Neifar, Isabelle Mollaret, L.H. Susan Lim, Sherman S. Hendrix, Louis Euzet Jan 2002

Phylogenetic Positions Of The Bothitrematidae And Neocalceostomatidae (Monopisthocotylean Monogeneans) Inferred From 28s Rdna Sequences, Jean-Lou Justine, Richard Jovelin, Lassâd Neifar, Isabelle Mollaret, L.H. Susan Lim, Sherman S. Hendrix, Louis Euzet

Harold W. Manter Laboratory of Parasitology: Faculty Publications

A molecular phylogeny was inferred from newly obtained partial (D1 domain) 28S rDNA gene sequences of Bothitrema bothi (Bothitrematidae), Neocalceostoma sp. (Neocalceostomatidae), Bravohollisia sp. (Ancyrocephalidae), and other already available sequences of Ancyrocephalidae, Anoplodiscidae, Pseudodactylogyridae, and Sundanonchidae, with the Diplectanidae as outgroup. Bothitrema, Anoplodiscus, and Sundanonchus formed a very robust clade that was the sister group to a group that included all other species examined. In this latter group, Neocalceostoma and Thaparocleidus were basal to a clade in which the Ancyrocephalidae and Pseudodactylogyridae were sister groups. Molecular results that suggest inclusion of the families Bothitrematidae, Anoplodiscidae, and Sundanonchidae in …

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Conformational Strictness Required For Maximum Activity And Stability Of Bovine Pancreatic Ribonuclease A As Revealed By Crystallographic Study Of Three Phe120 Mutants At 1.4 Å Resolution, Eri Chatani, Rikimaru Hayashi, Hideaki Moriyama, Tatzuo Ueki Jan 2002

Conformational Strictness Required For Maximum Activity And Stability Of Bovine Pancreatic Ribonuclease A As Revealed By Crystallographic Study Of Three Phe120 Mutants At 1.4 Å Resolution, Eri Chatani, Rikimaru Hayashi, Hideaki Moriyama, Tatzuo Ueki

School of Biological Sciences: Faculty Publications

The replacement of Phe120 with other hydrophobic residues causes a decrease in the activity and thermal stability in ribonuclease A (RNase A). To explain this, the crystal structures of wild-type RNase A and three mutants—F120A, F120G, and F120W—were analyzed up to a 1.4 Å resolution. Although the overall backbone structures of all mutant samples were nearly the same as that of wild-type RNase A, except for the C-terminal region of F120G with a high B-factor, two local conformational changes were observed at His119 in the mutants. First, His119 of the wild-type and F120W RNase A adopted an A position, whereas …

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A Preliminary Analysis Of Proteolytic Activity Of Excretory-Secretory Products From Cyathostominea, Jane L. Kinsella, J. Ralph Lichtenfels, Michael F. Ryan Jan 2002

A Preliminary Analysis Of Proteolytic Activity Of Excretory-Secretory Products From Cyathostominea, Jane L. Kinsella, J. Ralph Lichtenfels, Michael F. Ryan

Harold W. Manter Laboratory of Parasitology: Faculty Publications

The excretory-secretory product (ESP) derived from Cyathostominea in vitro was assessed, in terms of subunit composition, and proteolytic activity using as substrates azocasein and two synthetic fluorogenic peptides. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) resolved 13 subunits, and the presence of the protein cysteine proteinase activator dithiothreitol (DTT) revealed 21 subunits.DTTalso enhanced azocaseinolysis, and hydrolysis of carbobenzoxy-phenylalanyl-arginine-7-amido-4-methylcoumarin (Z-Phe-Arg-NHMec) and carbobenzoxy-arginyl-arginine-7-amido-4-methylcoumarin (Z-Arg-Arg-NHMec). At the optimum pH of 5.5, hydrolysis of Z-Phe-Arg-NHMec was three-fold greater than that of Z-Arg-Arg-NHMec suggesting that the proteolytic specificities of the ESP are more like those of papain or cathepsin L, rather than cathepsin B. In SDS-PAGE …

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In Vitro Mutation Induction By Gamma Irradiation For The Improvement Of A Triploid Banana Pisang Berangan (Aaa), Shadia Aldelgadir Mohamed Rayis Jan 2002

In Vitro Mutation Induction By Gamma Irradiation For The Improvement Of A Triploid Banana Pisang Berangan (Aaa), Shadia Aldelgadir Mohamed Rayis

Student Works (2000-2009)

Tissue culture and induced mutation techniques were used to generate variation for the improvement of Pisang Bcrangan cv. 'Intan' (AAA). Best field perform ing banana in vitroplants were multiplied and evaluated for better field performance, which included improved agronomic traits such as earliness in fruiting, short plant stature, high yielding capacity with desirable fruit quality and tolerance to Fusarium wilt. A suitable micropropagation medium for Pisang Berangan was established through modification of MS basic medium, which resulted in significant increase in shoot multiplication. Shoot-tip meristems of Pisang Berangan were then irradiated at 20, 30, 40 and 60 Gy to induce …

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Master Conservationist Awards, John Owens Jan 2002

Master Conservationist Awards, John Owens

John Owens: Speeches and Appearances

It is a distinct pleasure to be with you this evening to present the Master Conservationist awards. I appreciate the opportunity to recognize those who have gone the extra mile to enhance Nebraska's natural resources and our way of life. Their efforts take on even more importance in a year like this when drought conditions have threatened field crops, pastures, and rangeland, as well as water for livestock and the citizens of our state. Times like this underscore how important it is for us to recognize the delicate balance of nature.

The Master Conservationists we honor tonight have long-recognized the …

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Award Of Merit, Distinguished Achievement In Agriculture: Roger Mandigo, John Owens Jan 2002

Award Of Merit, Distinguished Achievement In Agriculture: Roger Mandigo, John Owens

John Owens: Speeches and Appearances

I am pleased to recognize Dr. Roger Mandigo as a recipient of the 2002 Gamma Sigma Delta Award of Merit for Distinguished Achievement in Agriculture. Roger, would you please come forward to receive your award.

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The Structure Of The Nucleus Of Odonaticola Polyhamatus (Gregarinea: Actinocephalidae), A Parasite Of Mnais Strigata (Hagen) (Odonata: Calopterygidae), Kasumi Hoshide, John J. Janovy Jr. Jan 2002

The Structure Of The Nucleus Of Odonaticola Polyhamatus (Gregarinea: Actinocephalidae), A Parasite Of Mnais Strigata (Hagen) (Odonata: Calopterygidae), Kasumi Hoshide, John J. Janovy Jr.

Harold W. Manter Laboratory of Parasitology: Faculty Publications

The nucleus of Odonaticola polyhamatus was isolated from the body and observed with light, scanning electron and transmission electron microscopy. The nucleus had a thick thread-like structure with which it was tied to the septum. This thread-like structure has not been reported or described previously. The gregarine nuclear surface was covered with a fine fibrous net. This is the first report of the surface structure of a gregarine nucleus as revealed by SEM. Inside the nuclear membrane was a thin honeycomb layer similar to that reported for some other gregarines. Several spherical nucleoli and numerous electron dense small structures were …

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Functional Group Interactions Of A 5-Ht3r Antagonist, Padmavati Venkataraman, Prasad Joshi, Srinivasan P. Venkatachalan, Mani Mathalagi, Harish S. Parihar, Karen S. Kirschbaum, Marvin K. Schulte Jan 2002

Functional Group Interactions Of A 5-Ht3r Antagonist, Padmavati Venkataraman, Prasad Joshi, Srinivasan P. Venkatachalan, Mani Mathalagi, Harish S. Parihar, Karen S. Kirschbaum, Marvin K. Schulte

PCOM Scholarly Works

Background: Lerisetron, a competitive serotonin type 3 receptor (5-HT 3R) antagonist, contains five functional groups capable of interacting with amino acids in the 5-HT3R binding site. Site directed mutagenesis studies of the 5-HT3AR have revealed several amino acids that are thought to form part of the binding domain of this receptor. The specific functional groups on the ligand that interact with these amino acids are, however, unknown. Using synthetic analogs of lerisetron as molecular probes in combination with site directed mutagenesis, we have identified some of these interactions and have proposed a model of the lerisetron binding site. Results: Two …

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Stat6 Mediates Interleukin-4 Growth Inhibition In Human Breast Cancer Cells, Jennifer L. Gooch, B. Christy, D. Yee Jan 2002

Stat6 Mediates Interleukin-4 Growth Inhibition In Human Breast Cancer Cells, Jennifer L. Gooch, B. Christy, D. Yee

PCOM Scholarly Works

In addition to acting as a hematopoietic growth factor, interleukin-4 (IL-4) inhibits growth of some transformed cells in vitro and in vivo. In this study, we show that insulin receptor substrate (IRS)-1, IRS-2, and signal transducer and activator of transcription 6 (STAT6) are phosphorylated following IL-4 treatment in MCF-7 breast cancer cells. STAT6 DNA binding is enhanced by IL-4 treatment. STAT6 activation occurs even after IRS-1 depletion, suggesting the two pathways are independent. To examine the role of STAT6 in IL-4-mediated growth inhibition and apoptosis, a full-length STAT6 cDNA was transfected into MCF-7 cells. Transient overexpression of STAT6 resulted in …

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In Vivo Effect Of Leukemia Inhibitory Factor (Lif) And An Anti-Lif Polyclonal Antibody On Murine Embryo And Fetal Development Following Exposure At The Time Of Transcervical Blastocyst Transfer, Michael H. Mitchell, R. James Swanson, Sergio Oehninger Jan 2002

In Vivo Effect Of Leukemia Inhibitory Factor (Lif) And An Anti-Lif Polyclonal Antibody On Murine Embryo And Fetal Development Following Exposure At The Time Of Transcervical Blastocyst Transfer, Michael H. Mitchell, R. James Swanson, Sergio Oehninger

Biological Sciences Faculty Publications

Leukemia inhibitory factor (LIF) enhances in vitro murine preimplantation development in a time- and dose-dependent fashion. Knockout experiments have demonstrated that endometrial LIF is essential for in vivo murine implantation. We assessed the impact of LIF and an anti-LIF polyclonal antibody (pab) on in vivo development and developed a novel and successful nonsurgical method of embryo transfer for this species, a transcervical blastocyst transfer technique. The objectives of this study were to evaluate the effects of LIF and the anti-LIF pab on 1) implantation, resorption, pregnancy, and viability rates and 2) the overall structural and skeletal development. Two-cell embryos were …

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Rickettsial Infection In Dermacentor Variabilis (Acari : Ixodidae) Inhibits Transovarial Transmission Of A Second Rickettsia, Kevin R. Macaluso, Daniel E. Sonenshine, Shane M. Ceraul, Abdu F. Azad Jan 2002

Rickettsial Infection In Dermacentor Variabilis (Acari : Ixodidae) Inhibits Transovarial Transmission Of A Second Rickettsia, Kevin R. Macaluso, Daniel E. Sonenshine, Shane M. Ceraul, Abdu F. Azad

Biological Sciences Faculty Publications

This study examined the ability of ticks to maintain multiple species of spotted fever group rickettsiae via transovarial transmission. Using a capillary feeding method, previously established Rickettsia montana- and Rickettsia rhipicephali-infected cohorts of Dermacentor variabilis (Say) were exposed to R. rhipicephali and R. montana, respectively, in two reciprocal challenge experiments. Eggs collected from individual females, for two successive generations, of each cohort were assessed for rickettsial infection by polymerase chain reaction for each challenge experiment. Assessment of the eggs from challenged ticks identified that both R. montana- and R. rhipicephali-infected ticks were refractory to their …

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Effects Of Indoleacetic Acid And Kinetin On Lipid Peroxidation Levels In Various Rat Tissues, İsmai̇l Çeli̇k, Yasi̇n Tülüce, Necati̇ Özok Jan 2002

Effects Of Indoleacetic Acid And Kinetin On Lipid Peroxidation Levels In Various Rat Tissues, İsmai̇l Çeli̇k, Yasi̇n Tülüce, Necati̇ Özok

Turkish Journal of Biology

This study was carried out to investigate whether plant growth regulators (PGRs) could affect lipid peroxidation (Malondialdehyde = MDA level) in erythrocyte, muscle, liver, heart and kidney tissue. Eighteen Sprague-Dawley albino rats were divided into three experimental groups: control and PGR-treated (indoleacetic acid and kinetin). Seventy-five ppm of PGRs, indoleacetic acid (IAA), and kinetin were administered orally to 6 rats ad libitum for 25 days. The hormone treatments caused different effects on the level of malondialdehyde (MDA) to those of the control rats. According to the results, while liver and kidney MDA levels were increased significantly by IAA administration in …

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Antimicrobial And Cytotoxic Activities Of Ceratonia Siliqua L. Extracts, Bi̇jen Kivçak, Tuba Mert, H. Tansel Öztürk Jan 2002

Antimicrobial And Cytotoxic Activities Of Ceratonia Siliqua L. Extracts, Bi̇jen Kivçak, Tuba Mert, H. Tansel Öztürk

Turkish Journal of Biology

The antimicrobial and cytotoxic activities of n-hexane, methanol, ethanol, ethyl acetate and water extracts of Ceratonia siliqua L. leaves were evaluated in this study. The antimicrobial activities of the extracts were reported against Escherichia coli ATCC 29998, Escherichia coli ATCC 25922, Escherichia coli ATCC 11230, Staphylococcus aureus ATCC 6538P, Staphylococcus aureus ATCC6538P, Staphylococcus aureus ATCC 29213, Staphylococcus epidermidis ATCC 12228, Salmonella thyphimurium CCM 5445, Enterobacter cloacae ATCC 13047, Enterococcus faecalis ATCC 29212, Pseudomonas aeroginosa ATCC 27853 as bacteria and Candida albicans ATCC 10239 as yeast-like fungi by the disc diffusion method. The cytotoxic activity of the extracts was evaluated by …

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Antimicrobial Peptides: A Potential Therapeutic Alternative For The Treatment Of Fish Diseases, Ali̇ye Sarmaşik Jan 2002

Antimicrobial Peptides: A Potential Therapeutic Alternative For The Treatment Of Fish Diseases, Ali̇ye Sarmaşik

Turkish Journal of Biology

Fish losses from infectious diseases are a significant problem in aquaculture worldwide. However, peptide antibiotics show potent activity against a broad range of pathogens including fish pathogens. Therefore, the ability of antimicrobial peptides to protect fish against infections caused by fish pathogens clearly shows the potential for utilisation of antimicrobial peptides for the treatment of fish diseases. The strategy of overexpressing the antimicrobial peptide genes in transgenic fish may provide a method of decreasing fish disease problems in aquaculture.

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Some Properties Of Crude Carboxymethyl Cellulase Of Aspergillus Niger Z10 Wild-Type Strain, Gökhan Coral, Burhan Arikan, M. Ni̇sa Ünaldi, Hati̇ce Güvenmez Jan 2002

Some Properties Of Crude Carboxymethyl Cellulase Of Aspergillus Niger Z10 Wild-Type Strain, Gökhan Coral, Burhan Arikan, M. Ni̇sa Ünaldi, Hati̇ce Güvenmez

Turkish Journal of Biology

A carboxymethyl cellulase enzyme was prepared from a wild type strain of Aspergillus niger Z10. Analyses of the enzyme preparation by SDS-PAGE revealed two protein bands showing cellulolytic activity. The molecular weight of these bands was estimated to be around 83,000 and 50,000. The optimum temperature of the enzyme was observed to be around 40 °C. It was found that the enzyme's activity has a broad pH range between 3 to 9 and 41.2% of the original activity was retained after heat treatment at 90 °C for 15 min.

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Epipelic And Epilithic Algae Of The Yedigöller Lakes (Erzurum-Turkey), Bülent Şahi̇n Jan 2002

Epipelic And Epilithic Algae Of The Yedigöller Lakes (Erzurum-Turkey), Bülent Şahi̇n

Turkish Journal of Biology

The epipelic and epilithic algae of the Yedigöller Lakes were studied qualitatively between June and September 2001. As a result 90 taxa (43 belonging to Bacillariophyta, 33 to Chlorophyta, 11 to Cyanophyta and three to Euglenophyta) were determined. Based on the algal community composition, the Yedigöller Lakes can be characterized as oligotrophic.

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The Treatment Efficiency Of Plankton In The İvedik Drinking Water Treatment Plant, Ankara, Ni̇lsun Demi̇r, Doğan Atay Jan 2002

The Treatment Efficiency Of Plankton In The İvedik Drinking Water Treatment Plant, Ankara, Ni̇lsun Demi̇r, Doğan Atay

Turkish Journal of Biology

The phyto-zooplankton composition and some physical and chemical properties of drinking water were investigated in the İvedik water treatment plant. The mean values of phytoplankton abundance were 641±92 and 438±55 ind/ml in the Kurtboğazı and Çamlıdere inlets, respectively. More than 50% of the phytoplankton belonging to the classes Bacillariophyceae, Chlorophyceae, Cryptophyceae and Dinophyceae were removed in the clarifiers. The treatment efficiency of phytoplankton ranged from 89 to 100% after the last chlorination. The mean values of zooplankton abundance were 93±23 and 59±18 ind/l in the Kurtboğazı and Çamlıdere inlets, respectively. The treatment efficiency of zooplankton varied between 97% and 100% …

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Effects Of Gibberellic Acid Treatment For Pollen Sterility Induction On The Physiological Activity And Endogenous Hormone Levels Of The Seed In Safflower, Hasan Baydar Jan 2002

Effects Of Gibberellic Acid Treatment For Pollen Sterility Induction On The Physiological Activity And Endogenous Hormone Levels Of The Seed In Safflower, Hasan Baydar

Turkish Journal of Biology

In this research, our aim was to determine the effects of gibberellic acid, which was applied to safflower plants (Carthamus tinctorius L. cv. Dinçer 5-118) for pollen sterility induction, on some physiological activity and endogenous hormone levels of the seeds. Exogenously applied gibberellic acid (GA_3) strongly influenced the endogenous hormone levels of the seeds by decreasing the levels of GA_3 and zeatin, and increasing the levels of indole-3-acetic acid (IAA) and abscisic acid (ABA). The lowered endogenous GA_3/ABA and zeatin/IAA ratios in the seeds significantly decreased the germination percentage and hypocotyl elongation, respectively. The seeds from GA_3 treated plants had …

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Electrical Conductivity Monitoring Of Soil Condition And Available N With Animal Manure And A Cover Crop, R. A. Eigenberg, John W. Doran, John A. Nienaber, Richard B. Ferguson, B. L. Woodbury Jan 2002

Electrical Conductivity Monitoring Of Soil Condition And Available N With Animal Manure And A Cover Crop, R. A. Eigenberg, John W. Doran, John A. Nienaber, Richard B. Ferguson, B. L. Woodbury

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

Development of sustainable agricultural management systems will depend, in part, on the ability to better use renewable resources, such as animal manure, and to synchronize the levels of soil available N with crop plant needs during the growing season. This study was conducted at the US Meat Animal Research Center in the central USA to determine whether differences in electromagnetic (EM) soil conductivity and available N levels over a growing season can be linked to feedlot manure/compost application and use of a green winter cover crop. A series of soil conductivity maps of a research cornfield were generated using global …

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Reductions In Grassland Species Evenness Increase Dicot Seedling Invasion And Spittle Bug Infestation, Brian J. Wilsey, H. Wayne Polley Jan 2002

Reductions In Grassland Species Evenness Increase Dicot Seedling Invasion And Spittle Bug Infestation, Brian J. Wilsey, H. Wayne Polley

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

Previous experiments that tested whether diverse plant communities have lower invasibility have all varied species richness. We experimentally varied evenness of four grassland species (three grasses and one forb) by planting a field experiment in Texas, and monitored the number of unplanted dicot and monocot species that invaded plots for two growing seasons. By varying evenness, we eliminated any sampling effect in our diversity treatment, because all plots contained the same plant species. Experimentally reducing evenness led to a greater number of dicot invaders, which emerged in plots throughout the growing season, but had less of an effect on monocot …

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Oviducal Sperm Storage In Turkeys: Spatial Distribution Of Sperm Within The Uterovaginal Junction Sperm-Storage Tubules, M. R. Bakst, Bryan T. Vinyard Jan 2002

Oviducal Sperm Storage In Turkeys: Spatial Distribution Of Sperm Within The Uterovaginal Junction Sperm-Storage Tubules, M. R. Bakst, Bryan T. Vinyard

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

The spatial distribution of sperm within the sperm storage tubules (SST) found in
the uterovaginal junction (UVJ) of the turkey is not known. In this study, we inseminated sperm stained with a fluorescent dye (Hoechst 33342) to determine their distribution in SST in the ventral, dorsal, and lateral regions of the proximal, middle, and distal regions of the UVJ. There was no preferential filling in the ventral-dorsal axis of the UVJ. In contrast, preferential filling of the SST was observed in the middle section of the UVJ. Here the individual SST were clearly longer and more pleomorphic than the SST …

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Physiology And Reproduction: Embryonic Development From First Cleavage Through Seventy-Two Hours Incubation In Two Strains Of Pekin Duck (Anas Platyrhynchos), V. Dupuy, B. Nersessian, M. R. Bakst Jan 2002

Physiology And Reproduction: Embryonic Development From First Cleavage Through Seventy-Two Hours Incubation In Two Strains Of Pekin Duck (Anas Platyrhynchos), V. Dupuy, B. Nersessian, M. R. Bakst

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

Embryonic mortality is a significant problem plaguing the commercial duck industry worldwide. Yet, an objective means to stage development of the duck embryo is lacking. Such a staging procedure, which is described in this study, is essential for the critical and reproducible assessment of embryo development. The morphological features associated with duck embryo development are very similar to those of the chicken, although the duck embryo develops more slowly. The staging scheme presented here provides objective morphological criteria describing the embryonic development of the duck.

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Beet Armyworm (Lepidoptera: Noctuidae) Host Plant Preferences For Oviposition, S. M. Greenberg, T. W. Sappington, T.-X. Liu Jan 2002

Beet Armyworm (Lepidoptera: Noctuidae) Host Plant Preferences For Oviposition, S. M. Greenberg, T. W. Sappington, T.-X. Liu

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

Beet armyworm, Spodoptera exigua (Hübner), oviposition preferences were determined on five host plants: cabbage (Brassica oleracea capitata L.), cotton (Gossypium hirsutum L.), bell pepper (Capsicum annuum L.), pigweed (Amaranthus retroflexus L.), and sunflower (Helianthus annuus L.) in no-choice, two-choice, and five-choice tests. Tests were conducted in the laboratory, greenhouse, and field cages. Oviposition preferences were compared on the basis of two measurements, the proportion of eggs laid on the plants to total that were deposited, and the oviposition preference index defined as [(number of eggs laid on the plant) - (number of eggs laid on …

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Soil Electrical Conductivity Classification: A Basis For Site-Specific Management In Semiarid Cropping Systems, Cinthia K. Johnson, David A. Mortensen, Brian J. Wienhold, John F. Shanahan, John W. Doran Jan 2002

Soil Electrical Conductivity Classification: A Basis For Site-Specific Management In Semiarid Cropping Systems, Cinthia K. Johnson, David A. Mortensen, Brian J. Wienhold, John F. Shanahan, John W. Doran

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

Site specific management (SSM) has the potential to improve both economic and ecological outcomes in agriculture. Effective SSM requires strong and temporally consistent relationships between identified management zones, underlying soil physical, chemical and biological parameters defining yield potential, and crop yield. In a farm-scale (250 ha) experiment in semiarid northeastern Colorado, each of eight 31-ha fields was individually mapped for soil apparent electrical conductivity (ECa) and classified into four management zones (ranges of ECa). Soil analyses revealed a strong negative relationship between ECa zones and soil parameters associated with innate fertility (P ≤ 0.06). …

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Response Of Irrigated Corn To Nitrogen Fertility Level Within Two Tillage Systems, Ardell D. Halvorson, Walter Bausch, Harold Duke, Curtis Reule Jan 2002

Response Of Irrigated Corn To Nitrogen Fertility Level Within Two Tillage Systems, Ardell D. Halvorson, Walter Bausch, Harold Duke, Curtis Reule

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

Irrigated farmers generally utilize intensive tillage to manage crop residues and prepare a seedbed for com. Nitrogen fertilizer management practices have been developed for conventional-till (CT) irrigated com production. Little information is available for no-till (NT) and reduced-till (RT) irrigated com production systems. This paper compares the response of irrigated continuous com to N fertility level under CT and NT or RT production systems on a Fort Collins clay loam soil from 1999 through 2001. Grain yields increased similarly with increasing available N level [soil NO3-N (0-3 ft) plus fertilizer N added] in 1999,2000, and 2001 for both …

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Starter Fertilizer Effects On Soybean Grain Yield And Quality, S.L. Osborne, W.E Riedell, J.L. Pikul Jr Jan 2002

Starter Fertilizer Effects On Soybean Grain Yield And Quality, S.L. Osborne, W.E Riedell, J.L. Pikul Jr

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

Fertilizing soybeans (Glycine max (L.) Merrill) is not an entirely new concept; for a number of years, scientists have investigated the effect of nitrogen (N) fertilizer on yield and quality of soybeans. The objective of this research was to investigate the effect of starter fertilizer N rates and sources on soybean yield, protein, and oil content in the cool soils of the Northern Great Plains. A field experiment was established within a two-year corn (Zea mays L.) soybean rotation. Using a split-plot design with four replications. Whole plots were no-till (NT) and conventional tillage (CT) and the split …

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Impact Of Intensive Cropping Systems On Physical Properties Of Surface Soils, G.A. Peterson, D.G. Westfall, L.A. Sherrod, T. M. Shaver Jan 2002

Impact Of Intensive Cropping Systems On Physical Properties Of Surface Soils, G.A. Peterson, D.G. Westfall, L.A. Sherrod, T. M. Shaver

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

The objective of this paper is to report the cumulative effects of cropping system intensification on the near surface soil physical properties (surface one inch of soil) within the Colorado dryland agroecoystem project, which has been in existence since 1986. Intensifying cropping systems from wheat-fallow to wheat-com-fallow to continuous cropping, increased crop residue return to the soil. Returning more residue to the soil surface: (I) decreased bulk density; (2) increased effective porosity; (3) increased sorptivity; (4) increased macro soil aggregation; and (5) appeared to improve potential water capture of the overall system. Increases in surface soil aggregation and effective porosity …

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