Digital Commons Network^™

Comparing The Direct And Community-Mediated Effects Of Disturbance On Plant Population Dynamics: Flooding, Herbivory And Mimulus Guttatus, Bret D. Elderd, Dan F. Doak

Faculty Publications

Competition, trophic interactions and abiotic disturbances play important roles in governing plant population dynamics, yet few studies have addressed their relative contributions or interacting effects. We used Life Table Response Experiment (LTRE) analysis, coupled with stochastic analyses, to examine how a major abiotic disturbance, flooding, influences the fitness and population growth of a common riparian plant, Mimulus guttatus, and how this effect compares and interacts with that exerted by herbivory. We also extended LTRE analysis to include nested factors, which enabled us to examine differences across experimental sites. These spatial contributions to changes in population growth rate, λ, were compared …

Mid-Season Prediction Of Wheat-Grain Yield Potential Using Plant, Soil, And Sensor Measurements, K. Girma, K. L. Martin, R. H. Anderson, D. B. Arnall, K. D. Brixey, M. A. Casillas, B. Chung, B. C. Dobey, S. K. Kamenidou, S. K. Kariuki, E. E. Katsalirou, J. C. Morris, J. Q. Moss, C. T. Rohla, B. J. Sudbury, B. S. Tubana, W. R. Raun

Faculty Publications

The components that define cereal-grain yield potential have not been well defined. The objective of this study was to collect many differing biological measurements from a long-term winter wheat (Triticum aestivum L.) study in an attempt to better define yield potential. Four treatments were sampled that annually received 0, 45, 90, and 135 kg N ha-1 at fixed rates of phosphorus (P) (30 kg ha-1) and potassium (K) (37 kg ha -1). Mid-season measurements of leaf color, chlorophyll, normalized difference vegetative index (NDVI), plant height, canopy temperature, tiller density, plant density, soil moisture, soil NH4-N, NO3-N, organic carbon (C), total …

Calcium Intake, Bone Mineral Density, And Percent Body Fat Of University Students, Beth Peterson

Honors Capstones

No abstract provided.

Extensive Individual Variation In L1 Retrotransposition Capability Contributes To Human Genetic Diversity, Maria Del Carmen Seleme, Melissa R. Vetter, Richard Cordaux, Laurel Bastone, Mark A. Batzer, Haig H. Kazazian

Faculty Publications

Despite being scarce in the human genome, active L1 retrotrans-posons continue to play a significant role in its evolution. Because of their recent expansion, many L1s are not fixed in humans, and, when present, their mobilization potential can vary among individuals. Previously, we showed that the great majority of retrotransposition events in humans are caused by highly active, or hot. L1s. Here, in four populations of diverse geographic origins (160 haploid genomes), we investigated the degree of sequence poly-morphism of three hot L1s and the extent of individual variation in mobilization capability of their allelic variants. For each locus, we …

Phylogenetic And Ecological Determinants Of The Neotropical Dawn Chorus, Karl S. Berg, Robb T. Brumfield, Victor Apanius

Faculty Publications

The concentration of avian song at first light (i.e. the dawn chorus) is widely appreciated, but has an enigmatic functional significance. One widely accepted explanation is that birds are active at dawn, but light levels are not yet adequate for foraging. In forest communities, the onset to singing should thus be predictable from the species' foraging strata, which is ultimately related to ambient light level. To test this, we collected data from a tropical forest of Ecuador involving 57 species from 27 families of birds. Time of first song was a repeatable, species-specific trait, and the majority of resident birds, …

Antarctic Climate Cooling And Response Of Diatoms In Glacial Meltwater Streams, Rhea M.M. Esposito, S. L. Horn, D. M. Mcknight, M. J. Cox, M. C. Grant, S. A. Spaulding, P. T. Doran, K. D. Cozzetto

Faculty Publications

To understand biotic responses to an Antarctic cooling trend diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40-60% of relative diatom abundance. Decreased solar radiation and air-temperatures reduce annual stream flow, raising the dominance of these Antarctic species to …

Antagonisms, Mutualisms And Commensalisms Affect Outbreak Dynamics Of The Southern Pine Beetle, Richard W. Hofstetter, James T. Cronin, Kier D. Klepzig, John C. Moser, Matthew P. Ayres

Faculty Publications

Feedback from community interactions involving mutualisms are a rarely explored mechanism for generating complex population dynamics. We examined the effects of two linked mutualisms on the population dynamics of a beetle that exhibits outbreak dynamics. One mutualism involves an obligate association between the bark beetle, Dendroctonus frontalis and two mycangial fungi. The second mutualism involves Tarsonemus mites that are phoretic on D. frontalis ("commensal"), and a blue-staining fungus, Ophiostoma minus. The presence of O. minus reduces beetle larval survival ("antagonistic") by outcompeting beetle-mutualistic fungi within trees yet supports mite populations by acting as a nutritional mutualist. These linked interactions potentially …

Dbrip: A Highly Integrated Database Of Retrotransposon Insertion Polymorphisms In Humans, Jianxin Wang, Lei Song, Deepak Grover, Sami Azrak, Mark A. Batzer, Ping Liang

Faculty Publications

Retrotransposons constitute over 40% of the human genome and play important roles in the evolution of the genome. Since certain types of retrotransposons, particularly members of the Alu, L1, and SVA families, are still active, their recent and ongoing propagation generates a unique and important class of human genomic diversity/polymorphism (for the presence and absence of an insertion) with some elements known to cause genetic diseases. So far, over 2,300, 500, and 80 Alu, L1, and SVA insertions, respectively, have been reported to be polymorphic and many more are yet to be discovered. We present here the Database of Retrotransposon …

Louisiana Agriculture Spring, 2006, Lsu Agcenter

Louisiana Agriculture

No abstract provided.

The Impact Of Data Quality On The Identification Of Complex Disease Genes: Experience From The Family Blood Pressure Program, Yen Pei Christy Chang, James Dae Ok Kim, Karen Schwander, Dabeeru C. Rao, Mike B. Miller, Alan B. Weder, Richard S. Cooper, Nicholas J. Schork, Michael A. Province, Alanna C. Morrison, Sharon L.R. Kardia, Thomas Quertermous, Aravinda Chakravarti

Faculty Publications

The application of genome-wide linkage scans to uncover susceptibility loci for complex diseases offers great promise for the risk assessment, treatment, and understanding of these diseases. However, for most published studies, linkage signals are typically modest and vary considerably from one study to another. The multicenter Family Blood Pressure Program has analyzed genome-wide linkage scans of over 12 000 individuals. Based on this experience, we developed a protocol for large linkage studies that reduces two sources of data error: pedigree structure and marker genotyping errors. We then used the linkage signals, before and after data cleaning, to illustrate the impact …

Effect Of Osmotic Immobilization On Refrigerated Storage And Cryopreservation Of Sperm From A Viviparous Fish, The Green Swordtail Xiphophorus Helleri, Huiping Yang, Leona Hazlewood, Ronald B. Walter, Terrence R. Tiersch

Faculty Publications

In this study, refrigerated storage and cryopreservation of sperm from the green swordtail Xiphophorus helleri were investigated. Previous cryopreservation research in this species utilized motile sperm because unlike in most fish species, Xiphophorus sperm can remain continuously motile after collection for a week with refrigerated storage. However, this species reproduces by internal fertilization, and given the significant requirements for motility within the female reproductive tract and potential limitations on sperm energetic capacities, immobilization of sperm prior to insemination could be used to improve fertilization success. Thus, the goal in this study was to use osmotic pressure to inhibit the motility …

Peptide Yy And Proglucagon Mrna Expression Patterns And Regulation In The Gut, Jun Zhou, Maren Hegsted, Kathleen L. Mccutcheon, Michael J. Keenan, Aochun Xi, Anne M. Raggio, Roy J. Martin

Faculty Publications

Objective: Peptide YY (PYY) and glucagon-like peptide-1 are important in the control of energy homeostasis and are both secreted from the gut in response to ingested nutrients. However, more studies are needed on nutrient regulation of their gene expression patterns in specific areas of the gut. This study detailed PYY and proglucagon (the gene that encodes glucagon-like peptide-1) gene expression patterns and regulation in the gut. We further examined the regulation of PYY and proglucagon mRNA by a diet containing fermentation- resistant starch (in vivo) and butyrate (in vitro). Research Methods and Procedures: Quantitative real time reverse transcriptase-polymerase chain reaction …

Interactions Between N- And C-Terminal Domains Of The Saccharomyces Cerevisiae High-Mobility Group Protein Hmo1 Are Required For Dna Bending, Kevin T. Bauerle, Edwin Kamau, Anne Grove

Faculty Publications

The Saccharomyces cerevisiae high-mobility group protein HMO1 is composed of two DNA-binding domains termed box A and box B, of which only box B is predicted to adopt a HMG fold, and a lysine-rich C-terminal extension. To assess the interaction between individual domains and their contribution to DNA binding, several HMO1 variants were analyzed. Using circular dichroism spectroscopy, thermal stability was measured. While the melting temperatures of HMO1-boxA and HMO1-boxB are 57.2 and 47.2 °C, respectively, HMO1-boxBC, containing box B and the entire C-terminal tail, melts at 46.1 °C, suggesting little interaction between box B and the tail. In contrast, …

No Variation And Low Synonymous Substitution Rates In Coral Mtdna Despite High Nuclear Variation, Michael E. Hellberg

Faculty Publications

Background: The mitochondrial DNA (mtDNA) of most animals evolves more rapidly than nuclear DNA, and often shows higher levels of intraspecific polymorphism and population subdivision. The mtDNA of anthozoans (corals, sea fans, and their kin), by contrast, appears to evolve slowly. Slow mtDNA evolution has been reported for several anthozoans, however this slow pace has been difficult to put in phylogenetic context without parallel surveys of nuclear variation or calibrated rates of synonymous substitution that could permit quantitative rate comparisons across taxa. Here, I survey variation in the coding region of a mitochondrial gene from a coral species (Balanophyllia elegans) …

Disturbance-Mediated Trophic Interactions And Plant Performance, Bret D. Elderd

Faculty Publications

Disturbances, such as flooding, play important roles in determining community structure. Most studies of disturbances focus on the direct effects and, hence, the indirect effects of disturbances are poorly understood. Within terrestrial riparian areas, annual flooding leads to differences in the arthropod community as compared to non-flooded areas. In turn, these differences are likely to alter the survival, growth, and reproduction of plant species via an indirect effect of flooding (i.e., changes in herbivory patterns). To test for such effects, an experiment was conducted wherein arthropod predators and herbivores were excluded from plots in flooded and non-flooded areas and the …

Rapid Evolution Of A Recently Retroposed Transcription Factor Yy2 In Mammalian Genomes, Chunqing Luo, Xiaochen Lu, Lisa Stubbs, Joomyeong Kim

Faculty Publications

YY2 was originally identified due to its unusual similarity to the evolutionarily well-conserved zinc finger gene YY1. In this study, we have determined the evolutionary origin and conservation of YY2 using comparative genomic approaches. Our results indicate that YY2 is a retroposed copy of YY1 that has been inserted into another gene locus named Mbtps2 (membrane-bound transcription factor protease site 2). This retroposition is estimated to have occurred after the divergence of placental mammals from other vertebrates based on the detection of YY2 only in the placental mammals. The N- and C-terminal regions of YY2 have evolved under different selection …

Bound For Canaan: The Underground Railroad And The War For The Soul Of America, Jill Ogline

Civil War Book Review

Outside the Lecture Hall

The Underground Railroad and Organized Abolitionism

Anthelmintic Resistance Of Gastrointestinal Parasites In Small Ruminants, Sherrill A. Fleming, Tom Craig, Ray M. Kaplan, James E. Miller, Christine Navarre, Mike Rings

Faculty Publications

No abstract provided.

Anthelmintic Resistance Of Gastrointestinal Parasites In Small Ruminants, Sherrill A. Fleming, Tom Craig, Ray M. Kaplan, James E. Miller, Christine Navarre, Mike Rings

Faculty Publications

No abstract provided.

Anthelmintic Resistance Of Gastrointestinal Parasites In Small Ruminants, Sherrill A. Fleming, Tom Craig, Ray M. Kaplan, James E. Miller, Christine Navarre, Mike Rings

Faculty Publications

No abstract provided.

Comparative Phylogeography In A Genus Of Coral Reef Fishes: Biogeographic And Genetic Concordance In The Caribbean, Michael S. Taylor, Michael E. Hellberg

Faculty Publications

Geographic barriers that limit the movement of individuals between populations may create or maintain phylogenetically discrete lineages. Such barriers are often inferred from geographic surveys of a single mitochondrial marker to identify phylogenetic splits. Mitochondrial DNA, however, has an effective population size one-fourth that of nuclear DNA, which can facilitate the rapid evolution of monophyletic mtDNA lineages in the absence of geographic barriers. The identification of geographic barriers will thus be more robust if barriers are proposed a priori, and tested with multiple independent genetic markers in multiple species. Here, we tested two proposed marine biogeographic breaks located at the …

Allele-Specific Deposition Of Macroh2a1 In Imprinting Control Regions, Jung Ha Choo, Jeong Do Kim, Jae Hoon Chung, Lisa Stubbs, Joomyeong Kim

Faculty Publications

In the current study, we analyzed the deposition patterns of macroH2A1 at a number of different genomic loci located in X chromosome and autosomes. MacroH2A1 is preferentially deposited at methylated CpG-rich regions located close to promoters. The macroH2A1 deposition patterns at the methylated CpG islands of several imprinted domains, including the imprinting control regions (ICRs) of Xist, Peg3, H19/Igf2, Gtl2/Dlk1 and Gnas domains, show consistent allele-specificity towards inactive, methylated alleles. The macroH2A1 deposition levels at the ICRs and other differentially methylated regions of these domains are also either higher or comparable to those observed at the inactive X chromosome of …

Epithelial Sodium Channel Allele T594m Is Not Associated With Blood Pressure Or Blood Pressure Response To Amiloride, John M. Hollier, Dan F. Martin, Darin M. Bell, Jia Ling Li, Mike G. Chirachanchai, Dileep V. Menon, David Leonard, Xiaodong Wu, Richard S. Cooper, Colin Mckenzie, Ronald G. Victor, Richard J. Auchus

Faculty Publications

The T594M allele of the epithelial sodium channel β-subunit has been proposed as a gain-of-function mutation leading to salt-sensitive hypertension in blacks that is particularly responsive to the specific sodium channel antagonist amiloride. However, the positive associations derive from small convenience samples, and the amiloride challenge study lacked a control group. We determined whether the T594M allele was associated with hypertension and blood pressure (BP) response to amiloride in 2 well-characterized random population samples including 3137 Dallas County subjects and 1666 Jamaican blacks. In multivariate models, the T594M allele was not predictive of systolic BP (adjusted odds ratio for hypertension …

Pelagic Functional Group Modeling: Progress, Challenges And Prospects, Raleigh R. Hood, Edward A. Laws, Robert A. Armstrong, Nicholas R. Bates, Christopher W. Brown, Craig A. Carlson, Fei Chai, Scott C. Doney, Paul G. Falkowski, Richard A. Feely, Marjorie A.M. Friedrichs, Michael R. Landry, J. Keith Moore, David M. Nelson, Tammi L. Richardson, Baris Salihoglu, Markus Schartau, Dierdre A. Toole, Jerry D. Wiggert

Faculty Publications

In this paper, we review the state of the art and major challenges in current efforts to incorporate biogeochemical functional groups into models that can be applied on basin-wide and global scales, with an emphasis on models that might ultimately be used to predict how biogeochemical cycles in the ocean will respond to global warming. We define the term "biogeochemical functional group" to refer to groups of organisms that mediate specific chemical reactions in the ocean. Thus, according to this definition, "functional groups" have no phylogenetic meaning-these are composed of many different species with common biogeochemical functions. Substantial progress has …

Coprophagy In A Cave-Adapted Salamander; The Importance Of Bat Guano Examined Through Nutritional And Stable Isotope Analyses, Danté B. Fenolio, G. O. Graening, Bret A. Collier, Jim F. Stout

Faculty Publications

During a two year population ecology study in a cave environment, 15 Eurycea (=Typhlotriton) spelaea were observed ingesting bat guano. Furthermore, E. spelaea capture numbers increased significantly during the time that grey bats (Myotis grisescens) deposited fresh guano. We investigated the hypothesis that this behaviour was not incidental to the capture of invertebrate prey, but a diet switch to an energy-rich detritus in an oligotrophic environment. Stable isotope assays determined that guano may be assimilated into salamander muscle tissue, and nutritional analyses revealed that guano is a comparable food source to potential invertebrate prey items. This is the first report …

The Structure Of The Carboxyltransferase Component Of Acetyl-Coa Carboxylase Reveals A Zinc-Binding Motif Unique To The Bacterial Enzyme, Patrick Bilder, Sandra Lightle, Graeme Bainbridge, Jeffrey Ohren, Barry Finzel, Fang Sun, Susan Holley, Loola Al-Kassim, Cindy Spessard, Michael Melnick, Marcia Newcomer, Grover L. Waldrop

Faculty Publications

Acetyl-coA carboxylase (ACC) is a central metabolic enzyme that catalyzes the committed step in fatty acid biosynthesis: biotin-dependent conversion of acetyl-coA to malonyl-coA. The bacterial carboxyltransferase (CT) subunit of ACC is a target for the design of novel therapeutics that combat severe, hospital-acquired infections resistant to the established classes of frontline antimicrobials. Here, we present the structures of the bacterial CT subunits from two prevalent nosocomial pathogens, Staphylococcus aureus and Escherichia coli, at a resolution of 2.0 and 3.0 Å, respectively. Both structures reveal a small, independent zinc-binding domain that lacks a complement in the primary sequence or structure of …

Crystal Structure Of The Hypoxia-Inducible Form Of 6-Phosphofructo-2- Kinase/Fructose-2,6-Bisphosphatase (Pfkfb3): A Possible New Target For Cancer Therapy, Song Gun Kim, Nathan P. Manes, M. Raafat El-Maghrabi, Yong Hwan Lee

Faculty Publications

The hypoxia-inducible form of 6-phosphofructo-2-kinase/fructose-2,6- bisphosphatase (PFKFB3) plays a crucial role in the progression of cancerous cells by enabling their glycolytic pathways even under severe hypoxic conditions. To understand its structural architecture and to provide a molecular scaffold for the design of new cancer therapeutics, the crystal structure of the human form was determined. The structure at 2.1 Å resolution shows that the overall folding and functional dimerization are very similar to those of the liver (PFKFB1) and testis (PFKFB4) forms, as expected from sequence homology. However, in this structure, the N-terminal regulatory domain is revealed for the first time …

Trehalose Uptake Through P2x7 Purinergic Channels Provides Dehydration Protection, Gloria D. Elliott, Xiang Hong Liu, Jennifer L. Cusick, Michael Menze, Jill Vincent, Trudy Witt, Steve Hand, Mehmet Toner

Faculty Publications

The tetra-anionic form of ATP (ATP4-) is known to induce monovalent and divalent ion fluxes in cells that express purinergic P2X 7 receptors and with sustained application of ATP it has been shown that dyes as large as 831 Da can permeate the cell membrane. The current study explores the kinetics of loading α,α-trehalose (342 Da) into ATP stimulated J774.A1 cells, which are known to express the purinergic P2X 7 receptor. Cells that were incubated at 37°C in a 50 mM phosphate buffer (pH 7.0) containing 225 mM trehalose and 5 mM ATP, were shown to load trehalose linearly over …

Nonrandom Processes Maintain Diversity In Tropical Forests, Christopher Wills, Kyle E. Harms, Richard Condit, David King, Jill Thompson, Fangliang He, Helene C. Muller-Landau, Peter Ashton, Elizabeth Losos, Liza Comita, Stephen Hubbell, James Lafrankie, Sarayudh Bunyavejchewin, H. S. Dattaraja, Stuart Davies, Shameema Esufali, Robin Foster, Nimal Gunatilleke, Savitri Gunatilleke, Pamela Hall, Akira Itoh, Robert John, Somboon Kiratiprayoon, Suzanne Loo De Lao, Marie Massa, Cheryl Nath, Md Nur Supardi Noor, Abdul Rahman Kassim, Raman Sukumar, Hebbalalu Satyanarayana Suresh, I. Fang Sun, Sylvester Tan, Takuo Yamakura

Faculty Publications

An ecological community's species diversity tends to erode through time as a result of stochastic extinction, competitive exclusion, and unstable host-enemy dynamics. This erosion of diversity can be prevented over the short term if recruits are highly diverse as a result of preferential recruitment of rare species or, alternatively, if rare species survive preferentially, which increases diversity as the ages of the individuals increase. Here, we present census data from seven New and Old World tropical forest dynamics plots that all show the latter pattern. Within local areas, the trees that survived were as a group more diverse than those …

The Prp19 U-Box Crystal Structure Suggests A Common Dimeric Architecture For A Class Of Oligomeric E3 Ubiquitin Ligases, Craig W. Vander Kooi, Melanie D. Ohi, Joshua A. Rosenberg, Michael L. Oldham, Marcia E. Newcomer, Kathleen L. Gould, Walter J. Chazin

Faculty Publications

Prp19 is an essential splicing factor and a member of the U-box family of E3 ubiquitin ligases. Prp19 forms a tetramer via a central coiled-coil domain. Here, we show the U-box domain of Prp19 exists as a dimer within the context of the Prp19 tetramer. A high-resolution structure of the homodimeric state of the Prp19 U-box was determined by X-ray crystallography. Mutation of the U-box dimer interface abrogates U-box dimer formation and is lethal in vivo. The structure of the U-box dimer enables construction of a complete model of Prp19 providing insights into how the tetrameric protein functions as an …