Digital Commons Network^™

Potassium, Phosphorus, Or Nitrogen Limit Root Allocation, Tree Growth, Or Litter Production In A Lowland Tropical Forest, S. Joseph Wright, Joseph B. Yavitt, Nina Wurzburger, Benjamin I. Turner, Edmund V.J. Tanner, Emma J. Sayer, Louis S. Santiago, Michael Kaspari, Lars O. Hedin, Kyle E. Harms, Milton N. Garcia, Marife D. Corre

Faculty Publications

We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32 plots of 40×40 m each. The addition of K was associated with significant decreases in stand-level fineroot biomass and, in a companion study of seedlings, decreases in allocation to roots and increases in height growth rates. The addition of K and N together was associated with significant …

Role Of Ph In A Nitric Oxide-Dependent Increase In Cytosolic Cl - In Retinal Amacrine Cells, Emily Mcmains, Evanna Gleason

Faculty Publications

Nitric oxide (NO) synthase-expressing neurons are found throughout the vertebrate retina. Previous work by our laboratory has shown that NO can transiently convert inhibitory GABAergic synapses onto cultured retinal amacrine cells into excitatory synapses by releasing Cl - from an internal store in the postsynaptic cell. The mechanism underlying this Cl -release is currently unknown. Because transport of Cl - across internal membranes can be coupled to proton flux, we asked whether protons could be involved in the NO-dependent release of internal Cl -. Using pH imaging and whole cell voltage-clamp recording, we addressed the relationship between cytosolic pH and …

Identification Of Cytochrome P450 2c2 Protein Complexes In Mouse Liver, Bin Li, Peter Yau, Byron Kemper

Faculty Publications

Interactions of microsomal cytochromes P450 (CYPs) with other proteins in the microsomal membrane are important for their function. In addition to their redox partners, CYPs have been reported to interact with other proteins not directly involved in their enzymatic function. In this study, proteins were identified that interact with CYP2C2 in vivo in mouse liver. Flag-tagged CYP2C2 was expressed exogenously in mouse liver and was affinity purified, along with associated proteins which were identified by MS and confirmed by Western blotting. Over 20 proteins reproducibly copurified with CYP2C2. The heterogeneous sedimentation velocity of CYP2C2 and associated proteins by centrifugation in …

Temporal And Spatial Variability In Culturable Pathogenic Vibrio Spp. In Lake Pontchartrain, Louisiana, Following Hurricanes Katrina And Rita, Olivia D. Nigro, Aixin Hou, Gayatri Vithanage, Roger S. Fujioka, Grieg F. Steward

Faculty Publications

We investigated the abundance, distribution, and virulence gene content of Vibrio cholerae, V. parahaemolyticus, and V. vulnificus in the waters of southern Lake Pontchartrain in Louisiana on four occasions from October 2005 to September 2006, using selective cultivation and molecular assays. The three targeted pathogenic vibrios were generally below the detection level in January 2006, when the water was cold (13°C), and most abundant in September 2006, when the lake water was warmest (30°C). The maximum values for these species were higher than reported previously for the lake by severalfold to orders of magnitude. The only variable consistently correlated with …

Some Low Homogenization Pressures Improve Certain Probiotic Characteristics Of Yogurt Culture Bacteria And Lactobacillus Acidophilus La-K1, T. Muramalla, K. J. Aryana

Faculty Publications

Lactobacillus delbrueckii ssp. bulgaricus, Streptococcus salivarius ssp. thermophilus, and Lactobacillus acidophilus are dairy cultures widely used in the manufacture of cultured dairy products. Commonly used homogenization pressures in the dairy industry are 13.80 MPa or less. It is not known whether low homogenization pressures can stimulate bacteria to improve their probiotic characteristics. Objectives were to determine the effect of homogenization at 0, 3.45, 6.90, 10.34, and 13.80 MPa on acid tolerance, bile tolerance, protease activity, and growth of L. delbrueckii ssp. bulgaricus LB-12, S. salivarius ssp. thermophilus ST-M5, and L. acidophilus LA-K. The cultures were individually inoculated in cool autoclaved …

Genetic Architecture Of Aluminum Tolerance In Rice (Oryza Sativa) Determined Through Genome-Wide Association Analysis And Qtl Mapping, Adam N. Famoso, Keyan Zhao, Randy T. Clark, Chih Wei Tung, Mark H. Wright, Carlos Bustamante, Leon V. Kochian, Susan R. Mccouch

Faculty Publications

Aluminum (Al) toxicity is a primary limitation to crop productivity on acid soils, and rice has been demonstrated to be significantly more Al tolerant than other cereal crops. However, the mechanisms of rice Al tolerance are largely unknown, and no genes underlying natural variation have been reported. We screened 383 diverse rice accessions, conducted a genome-wide association (GWA) study, and conducted QTL mapping in two bi-parental populations using three estimates of Al tolerance based on root growth. Subpopulation structure explained 57% of the phenotypic variation, and the mean Al tolerance in Japonica was twice that of Indica. Forty-eight regions associated …

Infrared Laser Ablation Sample Transfer For Maldi And Electrospray, Sung Gun Park, Kermit King Murray

Faculty Publications

We have used an infrared laser to ablate materials under ambient conditions that were captured in solvent droplets. The droplets were either deposited on a MALDI target for off-line analysis by MALDI time-of-flight mass spectrometry or flow-injected into a nanoelectrospray source of an ion trap mass spectrometer. An infrared optical parametric oscillator (OPO) laser system at 2.94 μm wavelength and approximately 1 mJ pulse energy was focused onto samples for ablation at atmospheric pressure. The ablated material was captured in a solvent droplet 1-2 mm in diameter that was suspended from a silica capillary a few millimeters above the sample …

Pathways To Sexual Risk Taking Among Female Adolescent Detainees, Vera Lopez, Albert M. Kopak, Alyssa G. Robillard, Mary Rogers Gillmore, Rhonda Conerly Holliday, Ronald L. Braithwaite

Faculty Publications

Sexual risk taking among female delinquents represents a significant public health problem. Research is needed to understand the pathways leading to sexual risk taking among this population. This study sought to address this issue by identifying and testing two pathways from child maltreatment to non-condom use among 329 White and 484 African American female adolescent detainees: a relational pathway and a substance use coping pathway. The relational pathway indicated that child maltreatment would be related to non-condom use via depressive self-concept and condom use self-efficacy. The substance use coping pathway suggested that depressive self-concept and alcohol-based expectancies for sexual enhancement …

Dietary Whey Protein Decreases Food Intake And Body Fat In Rats, June Zhou, Michael J. Keenan, Jack N. Losso, Anne M. Raggio, Li Shen, Kathleen L. Mccutcheon, Richard T. Tulley, Marc R. Blackman, Roy J. Martin

Faculty Publications

We investigated the effects of dietary whey protein on food intake, body fat, and body weight gain in rats. Adult (11-12 week) male Sprague-Dawley rats were divided into three dietary treatment groups for a 10-week study: control. Whey protein (HP-W), or high-protein content control (HP-S). Albumin was used as the basic protein source for all three diets. HP-W and HP-S diets contained an additional 24% (wt/wt) whey or isoflavone-free soy protein, respectively. Food intake, body weight, body fat, respiratory quotient (RQ), plasma cholecystokinin (CCK), glucagon like peptide-1 (GLP-1), peptide YY (PYY), and leptin were measured during and/or at the end …

Up-Regulation Of P-Glycoprotein Reduces Intracellular Accumulation Of Beta Amyloid: Investigation Of P-Glycoprotein As A Novel Therapeutic Target For Alzheimer's Disease, Alaa H. Abuznait, Courtney Cain, Drury Ingram, David Burk, Amal Kaddoumi

Faculty Publications

Objectives: Several studies have suggested the efflux transporter P-glycoprotein (P-gp) to play a role in the etiology of Alzheimer's disease through the clearance of amyloid beta (Aβ) from the brain. In this study, we aimed to investigate the possibility of P-gp as a potential therapeutic target for Alzheimer's disease by examining the impact of P-gp up-regulation on the clearance of Aβ, a neuropathological hallmark of Alzheimer's disease. Methods: Uptake studies for 125I-radiolabelled Aβ 1-40, and fluorescent immunostaining technique for P-gp and fluorescent imaging of Aβ 1-40 were carried out in LS-180 cells following treatment with drugs known to induce P-gp …

Incorporating Case Studies Into An Undergraduate Genetics Course, Marlene Murray

Faculty Publications

Genetics is considered one of the most challenging courses in the biology curricula at both the secondary and post secondary levels. Case based teaching has been shown to improve student perception and performance outcomes in both non-science and science courses. Thus in an effort to improve outcomes, case studies were integrated into an undergraduate genetics course as a supplement to lecture and replacement to recitation. Student perception and performance when case studies were used was compared to two previous years before the incorporation of case studies. Student course evaluations, pre and post surveys of student knowledge, and exam scores indicated …

Spatio-Temporal Patterns And Nutrient Status Of Macroalgae In A Heavily Managed Region Of Biscayne Bay, Florida, Usa, Ligia Collado-Vides, Viviana Mazzei, Travis Thyberg, Diego Lirman

Faculty Publications

The coastal bays of South Florida are located downstream of the Florida Everglades, where a comprehensive restoration plan will strongly impact the hydrology of the region. Submerged aquatic vegetation communities are common components of benthic habitats of Biscayne Bay, and will be directly affected by changes in water quality. This study explores community structure, spatio-temporal dynamics, and tissue nutrient content of macroalgae to detect and describe relationships with water quality. The macroalgal community responded to strong variability in salinity; three distinctive macroalgal assemblages were correlated with salinity as follows: (1) low-salinity, dominated by Chara hor-nemannii and a mix of filamentous …

Spatial Ecology Of The Palm-Leaf Skeletonizer, Homaledra Sabelella (Lepidoptera: Coleophoridae), James T. Cronin

Faculty Publications

Understanding the processes that determine the distribution of populations is a fundamental goal in ecology. In this study, I determined the relative contribution of space and the biotic and abiotic environment to the distribution of the palm-leaf skeletonizer Homaledra sabalella (PLS; Lepidoptera: Coleophoridae) among patchily distributed dwarf palmettos (Sabal minor; Arecaceae). Based on surveys conducted at two sites in the Sherburne Wildlife Management Area, Louisiana, I found that the distribution of the PLS was primarily related to local environmental conditions - number of PLS increased with palmetto height, was greater in dry versus wet habitats, and varied in an inconsistent …

Ψ-Ra: A Parallel Sparse Index For Genomic Read Alignment, M. Oǧuzhan Külekci, Wing Kai Hon, Rahul Shah, Jeffrey Scott Vitter, Bojian Xu

Faculty Publications

Background: Genomic read alignment involves mapping (exactly or approximately) short reads from a particular individual onto a pre-sequenced reference genome of the same species. Because all individuals of the same species share the majority of their genomes, short reads alignment provides an alternative and much more efficient way to sequence the genome of a particular individual than does direct sequencing. Among many strategies proposed for this alignment process, indexing the reference genome and short read searching over the index is a dominant technique. Our goal is to design a space-efficient indexing structure with fast searching capability to catch the massive …

No-Net-Loss Not Met For Nutrient Function In Freshwater Marshes: Recommendations For Wetland Mitigation Policies, Katie Hossler, Virginie Bouchard, M. Siobhan Fennessy, Serita D. Frey, Evelyn Anemaet, Ellen Herbert

Faculty Publications

Wetlands provide many important services throughout the world, with an estimated economic value that, in comparison to other ecosystems, far exceeds their relatively small global extent. In recognition of their importance, both national and international regulations exist to protect the world's remaining wetlands. Of growing interest is the “no-net-loss” policy which permits unavoidable destruction of wetlands if compensated by restoration of degraded wetlands or creation of new wetlands. The fundamental assumption of no-net-loss is that wetlands can be created which function equivalently to natural wetlands. One integral function that wetlands perform is cycling of carbon, nitrogen and phosphorus. Here we …

Alterations In The Transciptome And Antibiotic Susceptibility Of Staphylococcus Aureus Grown In The Presence Of Diclofenac, James T. Riordan, Joanne M. Dupre, Stephanie A. Cantore-Matyi, Atul Kumar-Singh, Yang Song, Shahrear Zaman, Sonia Horan, Nada S. Helal, Vijayaraj Nagarajan, Mohamed O. Elasri, Brian J. Wilkinson, John E. Gustafson

Faculty Publications

Background

Diclofenac is a non-steroidal anti-inflammatory drug (NSAID) which has been shown to increase the susceptibility of various bacteria to antimicrobials and demonstrated to have broad antimicrobial activity. This study describes transcriptome alterations in S. aureus strain COL grown with diclofenac and characterizes the effects of this NSAID on antibiotic susceptibility in laboratory, clinical and diclofenac reduced-susceptibility (Dc^RS) S. aureus strains.

Methods

Transcriptional alterations in response to growth with diclofenac were measured using S. aureus gene expression microarrays and quantitative real-time PCR. Antimicrobial susceptibility was determined by agar diffusion MICs and gradient plate analysis. Ciprofloxacin accumulation was measured …

A Genetically Tagged Psb27 Protein Allows Purification Of Two Consecutive Photosystem Ii (Psii) Assembly Intermediates In Synechocystis 6803, A Cyanobacterium, Haijun Liu, Johnna L. Roose, Jeffrey C. Cameron, Himadri B. Pakrasi

Faculty Publications

Photosystem II (PSII) is a large membrane bound molecular machine that catalyzes light-driven oxygen evolution from water. PSII constantly undergoes assembly and disassembly because of the unavoidable damage that results from its normal photochemistry. Thus, under physiological conditions, in addition to the active PSII complexes, there are always PSII subpopulations incompetent of oxygen evolution, but are in the process of undergoing elaborate biogenesis and repair. These transient complexes are difficult to characterize because of their low abundance, structural heterogeneity, and thermodynamic instability. In this study, we show that a genetically tagged Psb27 protein allows for the biochemical purification of two …

Racial Differences In The Responses To Shear Stress In Human Umbilical Vein Endothelial Cells, Deborah L. Feairheller, Joon-Young Park, Victor Rizzo, Boa Kim, Michael D. Brown

Faculty Publications

African American ethnicity is an independent risk factor for exaggerated oxidative stress, which is related to inflammation, hypertension, and cardiovascular disease. Recently, we reported that in vitro oxidative stress and inflammation levels differ between African American and Caucasian human umbilical vein endothelial cells (HUVECs), African American HUVECs having higher levels of both. However, it remains to be shown whether the cells would respond differently to external stimuli.

A Response To Mooi, Williams And Gill, Edward O. Wiley, Prosanta Chakrabarty, Matthew T. Craig, Matthew P. Davis, Nancy I. Holcroft, Richard L. Mayden, W. M.Leo Smith

Faculty Publications

No abstract provided.

Arabidopsis Pht1;5 Mobilizes Phosphate Between Source And Sink Organs And Influences The Interaction Between Phosphate Homeostasis And Ethylene Signaling, Vinay K. Nagarajan, Ajay Jain, Michael D. Poling, Anthony J. Lewis, Kashchandra G. Raghothama, Aaron P. Smith

Faculty Publications

Phosphorus (P) remobilization in plants is required for continuous growth and development. The Arabidopsis (Arabidopsis thaliana) inorganic phosphate (Pi) transporter Pht1;5 has been implicated in mobilizing stored Pi out of older leaves. In this study, we used a reverse genetics approach to study the role of Pht1;5 in Pi homeostasis. Under low-Pi conditions, Pht1;5 loss of function (pht1;5-1) resulted in reduced P allocation to shoots and elevated transcript levels for several Pi starvation-response genes. Under Pi-replete conditions, pht1;5-1 had higher shoot P content compared with the wild type but had reduced P content in roots. Constitutive overexpression of Pht1;5 had …

Regulation Of The Edwardsiella Ictaluri Type Iii Secretion System By Ph And Phosphate Concentration Through Esra, Esrb, And Esrc, Matthew L. Rogge, Ronald L. Thune

Faculty Publications

A recently described Edwardsiella ictaluri type III secretion system (T3SS) with functional similarity to the Salmonella pathogenicity island 2 T3SS is required for replication in channel catfish head-kidney-derived macrophages (HKDM) and virulence in channel catfish. Quantitative PCR and Western blotting identified low pH and phosphate limitation as conducive to expression of the E. ictaluri T3SS, growth conditions that mimic the phagosomal environment. Mutagenesis studies demonstrated that expression is under the control of the EsrAB two-component regulatory system. EsrB also induces upregulation of the AraC-type regulatory protein EsrC, which enhances expression of the EscB/EseG chaperone/effector operon in concert with EsrB and …

Acquisition Of Rickettsia Felis By Cat Fleas During Feeding, Kathryn E. Reif, Michael T. Kearney, Lane D. Foil, Kevin R. Macaluso

Faculty Publications

Evidence for horizontal routes of transmission for Rickettsia felis has come from detection of R. felis infection in vertebrates and multiple blood-feeding arthropods; however, infection of cat fleas, Ctenocephalides felis, during blood feeding has not been demonstrated. In this study, the ability of cat fleas to acquire R. felis through an infectious blood meal with subsequent vertical transmission was examined. Utilizing an artificial feeding system, Rickettsia-naive fleas were exposed to R. felis-infected blood meals and monitored for subsequent infection at weekly intervals for 4 weeks. At 7 days postexposure (dpe) ∼52% of fleas successfully acquired rickettsiae and R. felis DNA; …

Altered Gene Expression And Spongiotrophoblast Differentiation In Placenta From A Mouse Model Of Diabetes In Pregnancy, J. M. Salbaum, C. Kruger, X. Zhang, N. Arbour Delahaye, G. Pavlinkova, D. H. Burk, C. Kappen

Faculty Publications

Aims/hypothesis: Pregnancies complicated by diabetes have a higher risk of adverse outcomes for mothers and children, including predisposition to disease later in life, e.g. metabolic syndrome and hypertension. We hypothesised that adverse outcomes from diabetic pregnancies may be linked to compromised placental function, and sought to identify cellular and molecular abnormalities in diabetic placenta. Methods: Using a mouse model of diabetic pregnancy, placental gene expression was assayed at mid-gestation and cellular composition analysed at various stages. Genome-wide expression profiling was validated by quantitative PCR and tissue localisation studies were performed to identify cellular correlates of altered gene expression in diabetic …

Transcriptional Profiles Uncover Aspergillus Flavus-Induced Resistance In Maize Kernels, Meng Luo, Robert L. Brown, Zhi Yuan Chen, Abebe Menkir, Jiujiang Yu, Deepak Bhatnagar

Faculty Publications

Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus' infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus' challenge. Inoculated kernels were incubated 72 h via the laboratory-based …

Unintended Consequences: Potential Downsides Of The Air Force's Conversion To Biofuels, Mark N. Goltz, Charles A. Bleckmann, Charles M. Mackay, Khai Vuong, Jerrod P. Mccomb

Faculty Publications

The desire to reduce US dependence on foreign energy, ongoing environmental concerns, and the rising cost of petroleum have sparked significant development of greener alternative and renewable energy sources such as alcohol-based biofuels. To address these issues, the Department of Defense DOD has moved to diminish its reliance on petroleum for fueling aircraft and ground equipment. The US Air Force, in alignment with DOD objectives, has initiated several goals for reducing its use of energy: (1) decrease the use of petroleum-based fuel by 2 percent annually for the vehicle fleet, (2) increase the use of alternative fuel in motor vehicles …

Using Nanotechnology To Detect Nerve Agents, Mark N. Goltz, Dong-Shik Kim, Leeann Racz

Faculty Publications

Nanotechnology has opened a wide range of opportunities having potential impacts in areas as diverse as medicine and consumer products. In collaboration with researchers at the University of Toledo UT, Air Force Institute of Technology AFIT scientists are exploring the possibility of using a nanoscale organic matrix to detect organophosphate OP nerve agents. Current techniques for detecting OP compounds are expensive and time consuming. Developing a nanoscale organic matrix sensor would allow for direct, real-time sensing under field conditions. This article describes the science behind such a sensor and its possible applications. High-performance sensors are needed to protect Soldiers and …

Serum Igf-1 Concentrations Change With Soy And Seaweed Supplements In Healthy Postmenopausal American Women, Jane Teas, Mohammad R. Irhimeh, Susan Druker, Thomas G. Hurley, James R. Hébert, Todd M. Savarese, Mindy S. Kurzer

Faculty Publications

Insulin-like growth factor 1 (IGF-1) is an anabolic hormone important for growth and development. However, high-circulating serum concentrations in adults are associated with increased risk of postmenopausal breast cancer. Nutritional status and specific foods influence serum IGF-1 concentrations. Breast cancer incidence is typically low in Asian countries where soy is commonly consumed. Paradoxically, soy supplement trials in American women have reported significant increases in IGF-1. Seaweed also is consumed regularly in Asian countries where breast cancer risk is low. We investigated the possibility that seaweed could modify soy-associated increases in IGF-1 in American women. Thirty healthy postmenopausal women (mean age …

Infectivity Period Of Mice Inoculated With Human Adenoviruses, Rashmi Krishnapuram, Heather Kirk-Ballard, Aamri Zuberi, Nikhil V. Dhurandhar

Faculty Publications

Due to non-productive infections, mice are not a good model to study some human adenoviruses. However, mice provide an excellent model to study the metabolic effects of human adenovirus, Ad36. Research interest in Ad36 is increasing rapidly, and consequently an increase in the use of mice as a model is anticipated. However, little is known about the transmission potential of Ad36 from infected mice to other laboratory animals or personnel. While underestimating the infectivity could promote inadvertent spread of Ad36, overstating it could drain valuable laboratory resources and animals. Therefore, we determined the duration of infectivity in female C57BL/6J mice …

Multiplicity: An Organizing Principle For Cancers And Somatic Mutations, Lewis J. Frey, Stephen R. Piccolo, Mary E. Edgerton

Faculty Publications

Background: With the advent of whole-genome analysis for profiling tumor tissue, a pressing need has emerged for principled methods of organizing the large amounts of resulting genomic information. We propose the concept of multiplicity measures on cancer and gene networks to organize the information in a clinically meaningful manner. Multiplicity applied in this context extends Fearon and Vogelstein’s multi-hit genetic model of colorectal carcinoma across multiple cancers.

Methods: Using the Catalogue of Somatic Mutations in Cancer (COSMIC), we construct networks of interacting cancers and genes. Multiplicity is calculated by evaluating the number of cancers and genes linked by the measurement …

Understory Bird Communities In Amazonian Rainforest Fragments: Species Turnover Through 25 Years Post-Isolation In Recovering Landscapes, Philip C. Stouffer, Erik I. Johnson, Richard O. Bierregaard, Thomas E. Lovejoy

Faculty Publications

Inferences about species loss following habitat conversion are typically drawn from short-term surveys, which cannot reconstruct long-term temporal dynamics of extinction and colonization. A long-term view can be critical, however, to determine the stability of communities within fragments. Likewise, landscape dynamics must be considered, as second growth structure and overall forest cover contribute to processes in fragments. Here we examine bird communities in 11 Amazonian rainforest fragments of 1-100 ha, beginning before the fragments were isolated in the 1980s, and continuing through 2007. Using a method that accounts for imperfect detection, we estimated extinction and colonization based on standardized mist-net …