Life Sciences Commons^™

Estimating The Latitudinal Origins Of Migratory Birds Using Hydrogen And Sulfur Stable Isotopes In Feathers: Influence Of Marine Prey Base, Casey A. Lott, Timothy D. Meehan, Julie A. Heath

Julie Heath

Hydrogen stable isotope analysis of feathers is an important tool for estimating the natal or breeding latitudes of nearctic-neotropical migratory birds. This method is based on the latitudinal variation of hydrogen stable isotope ratios in precipitation in North America (iDp) and the inheritance of this variation in newly formed feathers (iDf). We hypothesized that the typically strong relationship between iDp and iDf would be decoupled in birds that forage in marine food webs because marine waters have relatively high iD values compared to iD values for local precipitation. Birds that forage on marine prey bases should also have feathers with …

Electricity Production By Geobacter Sulfurreducens Attached To Electrodes, Daniel R. Bond, Derek Lovley

Derek Lovley

Previous studies have suggested that members of the Geobacteraceae can use electrodes as electron acceptors for anaerobic respiration. In order to better understand this electron transfer process for energy production, Geobacter sulfurreducens was inoculated into chambers in which a graphite electrode served as the sole electron acceptor and acetate or hydrogen was the electron donor. The electron-accepting electrodes were maintained at oxidizing potentials by connecting them to similar electrodes in oxygenated medium (fuel cells) or to potentiostats that poised electrodes at +0.2 V versus an Ag/AgCl reference electrode (poised potential). When a small inoculum of G. sulfurreducens was introduced into …

Coastal Habitat Use By Wood Storks During The Non-Breeding Season, A. L. Bryan Jr., Karen F. Gaines, C. S. Eldridge

Karen F. Gaines

We documented roosting and foraging habitat use by Wood Storks during the post-breeding season in the coastal zone of Georgia from 1994-1998. Larger, more persistent aggregations of roosting storks typically oc- curred in enclosed wetlands on large estuarine islands. Smaller, more ephemeral aggregations tended to occur on salt marsh/upland ecotones, where storks appeared to be waiting for local conditions (tide levels) to become suit- able for foraging. Examination of habitat types within a 2-km radius of the larger (mean > 10 storks/survey) vs. smaller (mean <10 storks/survey) roosts showed that surrounding habitat structure, including those used for for- aging, were similar. Foraging storks typically fed in close proximity (median = 0.5 km) to large roosts, much closer than storks using coastal wetlands during the breeding season. Tidal creeks were used almost exclusively as foraging habitat (92%). Storks and other wading birds were almost always present when the study bird arrived. The foraging patterns of study birds and four storks carrying radios suggested that storks often used the same foraging sites and/ or marsh systems in the non-breeding season. Coastal Wood Storks apparently selected roosting sites based on the presence of conspecifics, abundant local prey, or possibly as shelter from adverse weather conditions

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 …

Kryptoperidinium Foliaceum Blooms In South Carolina: A Multi–Analytical Approach To Identification, Torstein Tengs

Dr. Torstein Tengs

Observations following the discovery of Kryptoperidinium foliaceum blooms in South Carolina (SC), USA, suggest that a multi-analytical approach, using a standard, minimal set of criteria, should be adopted for determining dinoflagellate species identity and taxonomic placement. A combination of morphological, molecular, and biochemical analyses were used to determine the identity of this “red tide” dinoflagellate, first documented in SC waters in the spring of 1998. Results from thecal plate tabulations (based on scanning electron and epifluorescence microscopy), gene sequence data, species-specific PCR probe assays, and microalgal pigment profiles were analyzed and compared to reference cultures of K. foliaceum. Comparative data …

Whole-Genome Analysis Of Dorsal-Ventral Patterning In The Drosophila Embryo, Angelike Stathopoulos, Madeleine Van Drenth, Albert Erives, Michele Markstein, Michael Levine

Michele Markstein

The maternal Dorsal regulatory gradient initiates the differentiation of several tissues in the early Drosophila embryo. Whole-genome microarray assays identified as many as 40 new Dorsal target genes, which encode a broad spectrum of cell signaling proteins and transcription factors. Evidence is presented that a tissue-specific form of the NF-Y transcription complex is essential for the activation of gene expression in the mesoderm. Tissue-specific enhancers were identified for new Dorsal target genes, and bioinformatics methods identified conserved cis-regulatory elements for coordinately regulated genes that respond to similar thresholds of the Dorsal gradient. The new Dorsal target genes and enhancers represent …

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 most successful …

Plant Rac-Like Gtpases Are Activated By Auxin And Mediate Auxin-Responsive Gene Expression, L. Z. Tao, Alice Cheung, H. M. Wu

Alice Cheung

The auxin indole-3-acetic acid is a key plant hormone essential for a broad range of growth and developmental processes. Here, we show that auxin activates Rac-like GTPases (referred to as Rac/Rop GTPases), and they in turn stimulate auxin-responsive gene expression. In particular, we show that overexpressing a wild-type tobacco Rac/Rop GTPase, NtRac1, and its constitutively active mutant form activates auxin-responsive gene expression. On the other hand, overexpressing dominant-negative NtRac1 and Rac-negative regulators, or reducing the endogenous NtRac1 level, suppresses auxin-induced gene expression. Furthermore, overexpression of NtRac1 activity or suppression of its expression in transgenic seedlings induces phenotypes that are similar …

Assessment Of Concentrated Flow Through Riparian Buffers, Michael G. Dosskey, Matthew J. Helmers, Dean E. Eisenhauer, Thomas G. Franti, Kyle D. Hoagland

Matthew J. Helmers

Concentrated flow of surface runoff from agricultural fields may limit the capability of riparian buffers to remove pollutants. This study was conducted on four farms in southeastern Nebraska to develop a method for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that it has on sediment-trapping efficiency. Field methods consisted of mapping field runoff areas and their pathways to and through riparian buffers to streams. Mathematical relationships were developed from a model (VFSMOD) that estimates sediment-trapping efficiency from the ratio of buffer area to field runoff area. Among the farms surveyed, riparian buffers averaged …

Cutting Edge: Persistent Viral Infection Prevents Tolerance Induction And Escapes Immune Control Following Cd28/Cd40 Blockade-Based Regimen, Thandi M. Onami, M. A. Williams, A. B. Adams, M. M. Durham, T. C. Pearson, R. Ahmed, C. P. Larsen

Thandi M. Onami

A continuing concern with CD28 and/or CD40 blockade-based strategies to induce tolerance and mixed chimerism is their potential to disrupt protective immunity to preexisting infections. In this report, we find that preexisting persistent infection with lymphocytic choriomeningitis virus (LCMV) clone 13 prevents the induction of tolerance, mixed chimerism, and donor-reactive T cell deletion. Mice continue to be refractory to tolerance induction even after viremia has been resolved and virus is present only at very low levels in peripheral tissues. Conversely, we find that the full tolerance regimen, or costimulation blockade alone, specifically inhibits already ongoing antiviral immune responses, leading to …

Efficacy Of Chrysosporium Lobatum Against Larvae Of Malaria Vector, Anopheles Stephensi In The Laboratory, Suman Sundar Mohanty, Soam Prakash

Soam Prakash

Decoding Cis-Regulatory Dnas In The Drosophila Genome, Michele Markstein, Michael Levine

Michele Markstein

Cis-regulatory DNAs control the timing and sites of gene expression during metazoan development. Changes in gene expression are responsible for the morphological diversification of metazoan body plans. However, traditional methods for the identification and characterization of cis-regulatory DNAs are tedious. During the past year, computational methods have been used to identify novel cis-DNAs within the entire Drosophila genome. These methods change the way that cis-DNAs will be analyzed in future studies and offer the promise of unraveling complex gene networks.

Short Communication: Relationship Between Body Growth And Mammary Development In Dairy Heifers, L F. Silva, M J. Vandehaar, Brian K. Whitlock, R P. Radcliff, H A. Tucker

Brian K Whitlock, PhD, DVM, DACT

Our objective was to determine if prepubertal rate of body weight (BW) gain, independent of diet, was related to mammary development of dairy heifers. Data from two studies recently conducted at Michigan State University were used to identify factors, within a dietary treatment group, that would account for variation in first lactation milk production or amount of mammary parenchymal DNA at the time of puberty. Factors analyzed for variation in milk production during first lactation were: postpartum BW, prepubertal BW gain, gestational BW gain, postpartum BW gain, body condition score (BCS) at breeding, and BCS at calving. Factors analyzed for …

A Mathematical Model Of Bacterial Aerotaxis, Borbala Mazzag, Alex Mogilner

Borbala Mazzag

No abstract provided.

Viscoelastic Properties And Changes In Pasting Characteristics Of Trifoliate Yam (Dioscorea Dumetorum) Starch After Harvest, Emmanuel Ohene Afoakwa, Samuel Sefa-Dedeh

Professor Emmanuel Ohene Afoakwa

Studies were conducted on the viscoelastic properties, as well as the changes in pasting characteristics, of trifoliate yam, Dioscorea dumetorum, starch during post-harvest hardening of the tubers. A 3x4 factorial experiment with blanching treatment time (0, 15 and 30 s) and storage time (0, 12, 24 and 36 h) as the respective variables was performed. The samples were evaluated for pasting temperature, viscosity at 95 _C, viscosity at 95 _C-Hold, viscosity at 50 _C and viscosity at 50 _C-Hold, as well as their changes during storage of the tubers, to determine the starch behaviour of the D. dumetorum tubers during …

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 …

The Regulation Of Actin Organization By Actin-Depolymerizing Factor In Elongating Pollen Tubes, C. Y. Chen, E. I. Wong, L. Vidali, A. Estavillo, P. K. Hepler, H. M. Wu, Alice Cheung

Alice Cheung

Pollen tube elongation is a polarized cell growth process that transports the male gametes from the stigma to the ovary for fertilization inside the ovules. Actomyosin-driven intracellular trafficking and active actin remodeling in the apical and subapical regions of pollen tubes are both important aspects of this rapid tip growth process. Actin-depolymerizing factor (ADF) and cofilin are actin binding proteins that enhance the depolymerization of microfilaments at their minus, or slow-growing, ends. A pollen-specific ADF from tobacco, NtADF1, was used to dissect the role of ADF in pollen tube growth. Overexpression of NtADF1 resulted in the reduction of fine, axially …

Textural And Microstructural Changes Associated With Post-Harvest Hardening Of Trifoliate Yam (Dioscorea Dumetorum) Pax Tubers, Emmanuel Ohene Afoakwa, Samuel Sefa-Dedeh

Professor Emmanuel Ohene Afoakwa

The textural and microstructural changes associated with the post-harvest hardening phenomenon of Dioscorea dumetorum tubers were studied to determine how texture relates to microstructure during the hardening process. A 2x2x4 factorial experiment with sample treatment,storage conditions and storage time as variables was performed. The tubers were harvested,matured and stored under prevailing tropical ambient conditions (28 _C) and cold room conditions (4 _C) for the study. All the samples were evaluated for their hardness (peak force) and adhesiveness (curve areas). Starch microscopy was done on the freshly harvested tubers,hardened tubers and tubers stored under low temperature conditions (4 _C) during the …

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 of N-ethylmaleimide …

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 …

Molecular Cloning And Characterization Of A Novel Mouse Macrophage C-Type Lectin, Mmgl2, Which Has A Distinct Carbohydrate Specificity From Mmgl1, Thandi M. Onami, M. Tsuiji, M. Fujimori, Y. Ohashi, N. Higashi, S. M. Hendrick, T. Irimura

Thandi M. Onami

A novel mouse macrophage galactose-type C-type lectin 2 (mMGL2) was identified by BLAST analysis of expressed sequence tags. The sequence of mMGL2 is highly homologous to the mMGL, which should now be called mMGL1. The open reading frame of mMGL2 contains a sequence corresponding to a type II transmembrane protein with 332 amino acids having a single extracellular C-type lectin domain. The 3'-untranslated region included long terminal repeats of mouse early transposon. The Mgl2 gene was cloned from a 129/SvJ mouse genomic library and sequenced. The gene spans 7,136 base pairs and consists of 10 exons, which is similar to …

Changes In Cell Wall Constituents And Mechanical Properties During Post-Harvest Hardening Of Trifoliate Yam Dioscorea Dumetorum (Kunth) Pax Tubers, Emmanuel Ohene Afoakwa, Samuel Sefa-Dedeh

Professor Emmanuel Ohene Afoakwa

In an attempt to investigate the changes leading to the rapid post-harvest hardening of the white cultivars of Dioscorea dumetorum tubers, alterations in the plant cell wall constituents and mechanical properties of the tubers were monitored. A 4x2 factorial experiment with storage time (0, 24, 48 and 72 h) and storage conditions [cold room (4 _C, 85–100% RH) and tropical ambient (28 _C, 62–100% RH)] as variables were performed. Harvested tubers were stored for 24, 48 and 72 h under 4 and 28 _C. Changes in mechanical properties, acid and neutral detergent fibres, lignin, cellulose and hemicellulose contents were monitored. …

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 …

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy L. Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei F. Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

Remote Sensing Of Site-Specific Soil Characteristics For Precision Farming, Amy L. Kaleita, Lei Tian

Amy L. Kaleita

A methodology for assessing distributed surface soil moisture content from optical remote sensing is developed. This study uses both ground-based and remotely sensed spectral measurements of soil reflectance in visible and near-infrared wavelengths and concurrent measurements of volumetric soil moisture within the top 6 cm to establish a relationship between spectral response and moisture. Various approaches, including principal component analyses and regression techniques are investigated to determine the potential for quantifying soil moisture from the spectral reflection data. Preliminary investigations have yielded R 2 values as high as 0.62 when comparing predictions to actual moisture values. Investigation of predicting soil …

Screening For Volatile Fatty Acids In Agricultural Air Using Solid Phase Microextraction And Gas Chromatography – Mass Spectrometry, Jarett P. Spinhirne, Jacek A. Koziel, David B. Parker, Darren L. Williams, N. Andy Cole, John M. Sweeten

Jacek A. Koziel

Volatile fatty acids (VFAs) are a major component of odorous gases associated with agricultural sources. Because of typically low VFA air concentrations, conventional air sampling methods including sorbent tubes and vacuum canisters are often not sensitive enough to detect them. Solid phase microextraction (SPME) was used in this research because it is very sensitive, reusable, fast, and combines sampling and sample preparation, allowing for rapid detection of low concentrations of organics in air. This research focused on 7 VFAs: acetic, propionic, isobutyric, butyric, isovaleric, valeric, and hexanoic acids. Field experiments were conducted to test this method for air sampling of …

Noninvasive Sampling And Analysis Of Bovine Breath Using Solid-Phase Microextraction And Gas Chromatography-Mass Spectrometry: A Feasibility Study, Jacek A. Koziel, Jarett P. Spinhirne, Norbert K. Chirase

Jacek A. Koziel

An experiment was conducted to examine the feasibility of detecting unique volatile organic biomarkers exhaled by healthy and morbid heifer calves on-site using noninvasive sampling with solid phase microextraction (SPME) and analysis with gas chromatography-mass spectrometry (GC-MS). Two heifers were selected on the bases of health status and were sampled from 5 to 15 min with a special facemask sampling system using DVB/Carboxen/PDMS 50/30 µ m and PDMS 100 µ m SPME fibers. The samples were sealed and transported to the laboratory and analyzed with ion trap GC-MS. Acetone, methyl ethyl ketone, toluene, pentadecane, and nonanal were detected in cattle …

Hyperspectral Imagery For Various Crop Growth Information Extraction, Haibo Yao, Lei Tian, Marvin Paulsen, Amy Kaleita, Mukti Singh

Amy L. Kaleita

Aerial hyperspectral imagery has potential for agriculture applications. The objective of this study is to identify significant wavelength ranges (image bands or band combinations) from hyperspectral imagery for different field information extraction. The field information include corn nitrogen content, plant population, yield, and grain quality such as oil, protein, and extractable starch. All the images were processed using the GA-SPCA (Genetic Algorithm based Selective Principal Component Analysis) method . T he GA-SPCA method can filter out significant image bands and reduce the image data dimension to only one principle component image through a cascade two-step dimension reduction process. It was …

An Overland Flow Sampler For Use In Vegetative Filters, D. Eisenhauer, Matthew J. Helmers, J. Brothers, M. Dosskey, T. Franti, A. Boldt, B. Strahm

Matthew J. Helmers

Vegetative filters (VF) are used to remove contaminants from agricultural runoff and improve surface water quality. State and federal cost-share funds are available to encourage landowners to install VF. The USDA-National Conservation Buffer Initiative calls for 3.2 million km of buffers to be installed by the year 2002. Numerous experimental plot and modeling studies have quantified the removal of sediments and other non-point source (NPS) contaminants from agricultural runoff by VF. Almost all of these studies have been conducted under controlled settings, including artificial sheet flow conditions, and using expensive, labor-intensive measurement systems. There is a critical need for simple, …