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2002

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Articles 1 - 20 of 20

Full-Text Articles in Life Sciences

An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs Dec 2002

An Inexpensive, Accurate Method For Measuring Leaf Area And Defoliation Through Digital Image Analysis, Matthew E. O'Neal, Douglas A. Landis, Rufus Isaacs

Matthew E. O'Neal

We report a protocol using a common desk-top scanner and public domain software for measuring existing leaf area and leaf area removed as a result of herbivory. We compared the accuracy and precision of this method to that of a standard leaf area meter. Both methods were used to measure metal disks of a known area, the area of soybean (Glycine max L.) leaves, and the area removed by simulating leaf feeding with a hole-punch. We varied the amount of injury across a low, medium, and high degree of simulated feeding. The mean area of 10 cm2 and 50 cm2 ...


Monitoring Pv In Corn And Soybean Oils By Nir Spectroscopy, Gülgün (Yildiz) Tiryaki Nov 2002

Monitoring Pv In Corn And Soybean Oils By Nir Spectroscopy, Gülgün (Yildiz) Tiryaki

Dr. Gülgün YILDIZ TIRYAKI

Gülgün Yildiz a, b, Randy L. Wehling*,a, and Susan L. Cuppett a a: Department of Food Science and Technology, University of Nebraska, Lincoln, Nebraska 68583-0919, and b: Olive Culture Research Institute, Universite Cd. No. 43, Bornova/Izmir, Turkey 3500. NIR spectroscopy was used successfully in our laboratory to monitor oxidation levels in vegetable oils. Calibration models were developed to measure PV in both soy and corn oils, using partial least squares (PLS) regression and forward stepwise multiple linear regression, from NIR transmission spectra. PV can be measured successfully in both corn and soy oils using a single calibration. The ...


Pmr6, A Pectate Lyase–Like Gene Required For Powdery Mildew Susceptibility In Arabidopsis, John P. Vogel, Ted K. Raab, Celine Schiff, Shauna C. Somerville Sep 2002

Pmr6, A Pectate Lyase–Like Gene Required For Powdery Mildew Susceptibility In Arabidopsis, John P. Vogel, Ted K. Raab, Celine Schiff, Shauna C. Somerville

Ted K. Raab

The plant genes required for the growth and reproduction of plant pathogens are largely unknown. In an effort to identify these genes, we isolated Arabidopsis mutants that do not support the normal growth of the powdery mildew pathogen Erysiphe cichoracearum. Here, we report on the cloning and characterization of one of these genes, PMR6. PMR6 encodes a pectate lyase-like protein with a novel C-terminal domain. Consistent with its predicted gene function, mutations in PMR6 alter the composition of the plant cell wall, as shown by Fourier transform infrared spectroscopy. pmr6-mediated resistance requires neither salicylic acid nor the ability to perceive ...


Hydrophobic Probe Binding Of Β-Lactoglobulin In The Native And Molten Globule State Induced By High Pressure As Affected By Ph, Kio3 And N-Ethylmaleimide, Jian Yang, Joseph R. Powers, Stephanie Clark, A. Keith Dunker, Barry G. Swanson Aug 2002

Hydrophobic Probe Binding Of Β-Lactoglobulin In The Native And Molten Globule State Induced By High Pressure As Affected By Ph, Kio3 And N-Ethylmaleimide, Jian Yang, Joseph R. Powers, Stephanie Clark, A. Keith Dunker, Barry G. Swanson

Stephanie Clark

High hydrostatic pressure (HHP) at 500 MPa and 50 °C induces β-LG into the molten globule state. Retinol, cis-parinaric acid (CPA), and 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence from pH 2.5 to 10.5 in the presence of the native and molten globule states of β-LG indicate that retinol binds to β-LG in the calyx, CPA at the surface hydrophobic site, and ANS in multiple hydrophobic sites. HHP treatment results in a decrease of β-LG affinity for retinol and CPA, suggesting conformational changes in the calyx and surface hydrophobic site of β-LG during HHP treatment. β-LG treated by HHP in the presence ...


Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim Aug 2002

Jun Dimerization Protein 2 Functions As A Progesterone Receptor N-Terminal Domain Coactivator, James S. Adelman, Suzanne E. Wardell, Viroj Boonyaratanakornkit, Ami Aronheim

James S. Adelman

The progesterone receptor (PR) contains two transcription activation function (AF) domains, constitutive AF-1 in the N terminus and AF-2 in the C terminus. AF-2 activity is mediated by a hormone-dependent interaction with a family of steroid receptor coactivators (SRCs). SRC-1 can also stimulate AF-1 activity through a secondary domain that interacts simultaneously with the primary AF-2 interaction site. Other protein interactions and mechanisms that mediate AF-1 activity are not well defined. By interaction cloning, we identified an AP-1 family member, Jun dimerization protein 2 (JDP-2), as a novel PR-interacting protein. JDP-2 was first defined as a c-Jun interacting protein that ...


No Difference Found In Ribosomal Dna Sequences From Physiologically Diverse Clones Of Karenia Brevis (Dinophyceae) From The Gulf Of Mexico, Torstein Tengs Jul 2002

No Difference Found In Ribosomal Dna Sequences From Physiologically Diverse Clones Of Karenia Brevis (Dinophyceae) From The Gulf Of Mexico, Torstein Tengs

Dr. Torstein Tengs

Maximum growth rate and toxin content were significantly different among five strains of Karenia brevis isolated from Texas and Florida when grown under identical culture conditions. Sequence analysis of the 18S rRNA gene and internal transcribed spacer (ITS) regions revealed, however, that all five strains were identical. Consequently, a clear genetic basis for physiological variability among various geographical isolates of K. brevis from the Gulf of Mexico could not be assessed using these genetic markers. Both the ITS and 18S rRNA regions may be useful in species-specific probe selection. At the intra-specific level, however, an alternative marker will be needed ...


Mechanism Of Abietadiene Synthase Catalysis: Stereochemistry And Stabilization Of The Cryptic Pimarenyl Carbocation Intermediates, Reuben J. Peters, Matthew M. Ravn, Robert M. Coates, Rodney Croteau Jun 2002

Mechanism Of Abietadiene Synthase Catalysis: Stereochemistry And Stabilization Of The Cryptic Pimarenyl Carbocation Intermediates, Reuben J. Peters, Matthew M. Ravn, Robert M. Coates, Rodney Croteau

Reuben J. Peters

Abietadiene synthase (AS) catalyzes the complex cyclization-rearrangement of (E,E,E)-geranylgeranyl diphosphate (8, GGPP) to a mixture of abietadiene (1a), double bond isomers 2a-4a and pimaradienes 5a-7a as a key step in the biosynthesis of the abietane resin acid constituents (1b-4b) of conifer oleoresin. The reaction proceeds at two active sites by way of the intermediate, copalyl diphosphate (9). In the second site, a putative tricyclic pimaradiene or pimarenyl(+) carbocation intermediate of undefined C13 stereochemistry and annular double bond position is formed. Three 8-oxy-17-nor analogues of 9 (17 and 19a,b) and three isomeric 15,16-bisnorpimarenyl-N-methylamines (26a-c) were synthesized ...


Abietadiene Synthase Catalysis:  Conserved Residues Involved In Protonation-Initiated Cyclization Of Geranylgeranyl Diphosphate To (+)-Copalyl Diphosphate, Reuben J. Peters, Rodney B. Croteau Feb 2002

Abietadiene Synthase Catalysis:  Conserved Residues Involved In Protonation-Initiated Cyclization Of Geranylgeranyl Diphosphate To (+)-Copalyl Diphosphate, Reuben J. Peters, Rodney B. Croteau

Reuben J. Peters

Abietadiene synthase catalyzes two sequential, mechanistically distinct cyclization reactions in the formation of a mixture of abietadiene double bond isomers as the committed step in resin acid biosynthesis. Each reaction is carried out at a separate active site residing in a structurally distinct domain, and the reactions are kinetically separable. The first cyclization reaction is initiated by protonation of the terminal double bond of the universal diterpene precursor, geranylgeranyl diphosphate. The pH dependence of the overall reaction is consistent with an acid-base catalytic mechanism, and a divalent metal ion plays a role in this reaction probably by binding the diphosphate ...


Language Plasticity Revealed By Electroencephalogram Mapping, Armando F. Rocha, Flávia B. Foz Jan 2002

Language Plasticity Revealed By Electroencephalogram Mapping, Armando F. Rocha, Flávia B. Foz

Armando F Rocha

Reasoning is the result of the computations made by intelligent systems, for instance those in the brain. It is not an abstract concept because calculations performed by computations are very concrete transactions among the different central processing unit components. Entropy measurements are proposed here to disclose the plasticity of the cerebral processing associated with language comprehension in video game playing. It is also assumed that entropy may be evaluated from the correlation coefficients obtained for the game event-related activity calculated for the different electroencephalogram derivations in the 10/20 system. The brain mapping derived from these entropy measurements clearly demonstrates ...


Self Reliant Agriculture For Arid Lands, David A. Bainbridge Jan 2002

Self Reliant Agriculture For Arid Lands, David A. Bainbridge

David A Bainbridge

More than a billion people face the challenge of supporting themselves in the world's arid lands. Much can be improved by refining and adopting the best traditional practices and crops from around the world. The lessons learned can also help develop new and improved agronomic practices and crops.


Water-Based Recreational Benefits Of Conservation Programs: The Case Of Conservation Tillage On U.S. Cropland, Kathy Baylis, Peter Feather, Merritt Padgitt, Carmen Sandretto Jan 2002

Water-Based Recreational Benefits Of Conservation Programs: The Case Of Conservation Tillage On U.S. Cropland, Kathy Baylis, Peter Feather, Merritt Padgitt, Carmen Sandretto

Kathy Baylis

No abstract provided.


Discovery Of The Toxic Dinoflagellate Pfiesteria In Northern European Waters, Torstein Tengs Jan 2002

Discovery Of The Toxic Dinoflagellate Pfiesteria In Northern European Waters, Torstein Tengs

Dr. Torstein Tengs

Several dinoflagellate strains of the genus Pfiesteria were isolated by culturing techniques from sediment samples taken in the Oslofjord region of Norway. Pfiesteria piscicida, well known as a fish killer from the Atlantic coast of America, was identified by genetic methods and light microscopy. The related species Pfiesteria shumwayae was attracted from the sediment by the presence of fish, and has proved toxic. This present survey demonstrates the wide distribution of these potentially harmful species, but so far they have not been connected with fish kills in Europe.


Galactose-Binding Lectin From The Seeds Of Champedak (Artocarpus Integer): Sequences Of Its Subunits And Interactions With Human Serum O-Glycosylated Glycoproteins, Onn Haji Hashim Jan 2002

Galactose-Binding Lectin From The Seeds Of Champedak (Artocarpus Integer): Sequences Of Its Subunits And Interactions With Human Serum O-Glycosylated Glycoproteins, Onn Haji Hashim

Onn Haji Hashim

Our group has previously reported the isolation, partial characterisation, and application of a Galbeta1-3GalNAc- and IgA1-reactive lectin from the seeds of champedak (Artocarpus integer). In the present study, we have subjected the purified lectin to reverse-phase high performance liquid chromatography and sequenced its subunits. Determination of the N-terminal sequence of the first 47 residues of the large subunit demonstrated at least 95% homology to the N-terminal sequence of the alpha chains of a few other galactose-binding Artocarpus lectins, The two smaller subunits of the lectin, each comprised of 21 amino acid residues, demonstrated minor sequence variability. Their sequences were generally ...


Influence Of An Extreme High Water Event On Survival, Reproduction, And Distribution Of Snail Kites In Florida, Usa, Robert Bennetts, Wiley Kitchens, Victoria Dreitz Jan 2002

Influence Of An Extreme High Water Event On Survival, Reproduction, And Distribution Of Snail Kites In Florida, Usa, Robert Bennetts, Wiley Kitchens, Victoria Dreitz

Victoria Dreitz

No abstract provided.


Evaluation Of Antemortem Sampling To Estimate Chronic Wasting Disease Prevalence In Free-Ranging Mule Deer, Lisa Wolfe, Mary Conner, T Baker, Victoria Dreitz, Kenneth Burnham, Elizabeth Williams, N T. Hobbs, Michael Miller Jan 2002

Evaluation Of Antemortem Sampling To Estimate Chronic Wasting Disease Prevalence In Free-Ranging Mule Deer, Lisa Wolfe, Mary Conner, T Baker, Victoria Dreitz, Kenneth Burnham, Elizabeth Williams, N T. Hobbs, Michael Miller

Victoria Dreitz

No abstract provided.


Athletes' Use Of Imagery In The Off-Season, Jennifer Cumming, Craig Hall Jan 2002

Athletes' Use Of Imagery In The Off-Season, Jennifer Cumming, Craig Hall

Jennifer Cumming

The purpose of this study was to examine the influence of competitive level on an athletes’ use of imagery in the off-season, and to examine whether their use of imagery was related to their physical and technical preparation. Three hundred and twenty-four regional, provincial, and national level athletes were recruited to participate in this study from 10 different sports. Participants were asked to complete a modified version of the Sport Imagery Questionnaire (SIQ; Hall, Mack, Paivio, & Hausenblas, 1998) that was designed to reflect an athletes’ use of imagery in the off-season. MANOVAs indicated that competitive level differences existed in athletes ...


Foraging Ecology And Depredation Management Of Great Blue Herons At Mississippi Catfish Farms, James F. Glahn, Brian S. Dorr, John B. Harrell, Lester Khoo Jan 2002

Foraging Ecology And Depredation Management Of Great Blue Herons At Mississippi Catfish Farms, James F. Glahn, Brian S. Dorr, John B. Harrell, Lester Khoo

Brian S Dorr

No abstract provided.


Problems With Developmental Stability In Two Rodent Species From Chornobyl, Taras K. Oleksyk, Michael H. Smith, Sergiy P. Gashchak, James M. Novak, James R. Purdue Jan 2002

Problems With Developmental Stability In Two Rodent Species From Chornobyl, Taras K. Oleksyk, Michael H. Smith, Sergiy P. Gashchak, James M. Novak, James R. Purdue

James M. Novak

Changes in developmental patterns are some of the most important effects that may be observed at radioactively contaminated sites like those at Chornobyl. Developmental instability may arise from the interactions between an organism's genotype and its environment and be manifested as deviant morphology. Fluctuating asymmetry (FA) is a measure of deviations from the expected bilateral symmetry of the body. Our objective was to test for differences in FA in two rodent species (Apodemus flavicollis and Clethrionomys glareolus) that live in habitats suirounding the failed Chornobyl reactor. Rodents were collected from four different locations (two contaminated and two reference sites ...


Reactivity Profiles Of Ligands Of Mammalian Retinoic Acid Receptors: A Preliminary Corepa Analysis, Steven P. Bradbury, G. T. Ankley, O. G. Mekenyan, V. . Kamenska, P. K. Schmieder Jan 2002

Reactivity Profiles Of Ligands Of Mammalian Retinoic Acid Receptors: A Preliminary Corepa Analysis, Steven P. Bradbury, G. T. Ankley, O. G. Mekenyan, V. . Kamenska, P. K. Schmieder

Steven P. Bradbury

Retinoic acid and associated derivatives comprise a class of endogenous hormones that bind to and activate different families of retinoic acid receptors (RARs, RXRs), and control many aspects of vertebrate development. Identification of potential RAR and RXR ligands is of interest both from a pharmaceutical and toxicological perspective. The recently developed COREPA (COmmon REactivity PAttern) algorithm was used to establish reactivity profiles for a limited data set of retinoid receptor ligands in terms of activation of three RARs (a, b, g) and an RXR (a). Conformational analysis of a training set of retinoids and related analogues in terms of thermodynamic ...


Narrowing Historical Uncertainty: Probabilistic Classification Of Ambiguously Identified Tree Species In Historical Forest Survey Data, David J. Mladenoff, Sally E. Dahir, Eric V. Nordheim, Lisa A. Schulte, Glenn G. Guntenspergen Jan 2002

Narrowing Historical Uncertainty: Probabilistic Classification Of Ambiguously Identified Tree Species In Historical Forest Survey Data, David J. Mladenoff, Sally E. Dahir, Eric V. Nordheim, Lisa A. Schulte, Glenn G. Guntenspergen

Lisa A. Schulte Moore

Historical data have increasingly become appreciated for insight into the past conditions of ecosystems. Uses of such data include assessing the extent of ecosystem change; deriving ecological baselines for management, restoration, and modeling; and assessing the importance of past conditions on the composition and function of current systems. One historical data set of this type is the Public Land Survey (PLS) of the United States General Land Office, which contains data on multiple tree species, sizes, and distances recorded at each survey point, located at half-mile (0.8-km) intervals on a 1-mi (1.6 km) grid. This survey method was ...