Liana Abundance, Diversity, And Distribution On Barro Colorado Island, Panama, Stefan A. Schnitzer, Scott A. Mangan, James W. Dalling, Claire Baldeck, Stephen P. Hubbell, Alicia Ledo, Helene C. Muller-Laudau, Michael F. Tobin, Salomón Aguilar, David Brassfield, Andres Hernandez, Suzanne Lao, Rolando Perez, Oldemar Valdes, Suzanne R. Yorke

Biological Sciences Faculty Research and Publications

Lianas are a key component of tropical forests; however, most surveys are too small to accurately quantify liana community composition, diversity, abundance, and spatial distribution – critical components for measuring the contribution of lianas to forest processes. In 2007, we tagged, mapped, measured the diameter, and identified all lianas ≥1 cm rooted in a 50-ha plot on Barro Colorado Island, Panama (BCI). We calculated liana density, basal area, and species richness for both independently rooted lianas and all rooted liana stems (genets plus clones). We compared spatial aggregation patterns of liana and tree species, and among liana species that varied …

Mir-786 Regulation Of A Fatty-Acid Elongase Contributes To Rhythmic Calcium-Wave Initiation In C. Elegans, Benedict J. Kemp, Erik Allman, Lois Immerman, Megan Mohnen, Maureen A. Peters, Keith Nerhke, Allison L. Abbott

Biological Sciences Faculty Research and Publications

Background: Rhythmic behaviors are ubiquitous phenomena in animals. In C. elegans, defecation is an ultradian rhythmic behavior: every ∼50 s a calcium wave initiating in the posterior intestinal cells triggers the defecation motor program that comprises three sequential muscle contractions. Oscillatory calcium signaling is central to the periodicity of defecation. The posteriormost intestinal cells function as the pacemaker for this rhythmic behavior, although it is unclear how the supremacy of these cells for calcium-wave initiation is controlled.

Results: We describe how the loss of the mir-240/786 microRNA cluster, which results in arrhythmic defecation, causes ectopic intestinal calcium-wave initiation. mir-240/786 expression …

The Enzymes Of Biotin Dependent Co(2) Metabolism: What Structures Reveal About Their Reaction Mechanisms, Grover L. Waldrop, Hazel M. Holden, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Biotin is the major cofactor involved in carbon dioxide metabolism. Indeed, biotin-dependent enzymes are ubiquitous in nature and are involved in a myriad of metabolic processes including fatty acid synthesis and gluconeogenesis. The cofactor, itself, is composed of a ureido ring, a tetrahydrothiophene ring, and a valeric acid side chain. It is the ureido ring that functions as the CO₂ carrier. A complete understanding of biotin-dependent enzymes is critically important for translational research in light of the fact that some of these enzymes serve as targets for anti-obesity agents, antibiotics, and herbicides. Prior to 1990, however, there was a …

Dpy-30 Domain And Its Flanking Sequence Mediate The Assembly Modulation Of Flagellar Radial Spoke Complexes, Radhika Gopal, Kenneth W. Foster, Pinfen Yang

Biological Sciences Faculty Research and Publications

RIIa is known as the dimerization and docking (D/D) domain of the cyclic AMP (cAMP)-dependent protein kinase. However, numerous molecules, including radial spoke protein 2 (RSP2) in Chlamydomonas flagella, also contain an RIIa or a similar DPY-30 domain. To elucidate new roles of D/D domain-containing proteins, we investigated a panel of RSP2 mutants. An RSP2 mutant had paralyzed flagella defective in RSP2 and multiple subunits near the spokehead. New transgenic strains lacking only the DPY-30 domain in RSP2 were also paralyzed. In contrast, motility was restored in strains that lacked only RSP2’s calmodulin- binding C-terminal region. These cells swam normally …

Deep Diversification And Long-Term Persistence In The South American ‘Dry Diagona’: Integrating Continent-Wide Phylogeography And Distribution Modeling Of Geckos, Fernanda P. Werneck, Tony Gamble, Guarino R. Colli, Miguel T. Rodrigues, Jack W. Sites Jr.

Biological Sciences Faculty Research and Publications

The relative influence of Neogene geomorphological events and Quaternary climatic changes as causal mechanisms on Neotropical diversification remains largely speculative, as most divergence timing inferences are based on a single locus and have limited taxonomic or geographic sampling. To investigate these influences, we use a multilocus (two mitochondrial and 11 nuclear genes) range‐wide sampling of Phyllopezus pollicaris, a gecko complex widely distributed across the poorly studied South American ‘dry diagonal’ biomes. Our approach couples traditional and model‐based phylogeography with geospatial methods, and demonstrates Miocene diversification and limited influence of Pleistocene climatic fluctuations on P. pollicaris. Phylogeographic structure and …

Expression Of Recombinant Earli1, A Hybrid Proline-Rich Protein Of Arabidopsis, In Escherichia Coli And Its Inhibition Effect To The Growth Of Fungal Pathogens And Saccharomyces Cerevisiae, Lan Li, Chen Zhang, Dan Xu, Michael Schläppi, Zi-Qin Xu

Biological Sciences Faculty Research and Publications

EARLI1 is an Arabidopsis gene with pleiotropic effects previously shown to have auxiliary functions in protecting plants against freezing-induced cellular damage and promoting germinability under low-temperature and salinity stresses. Here we determined whether recombinant EARLI1 protein has anti-fungal activity. Recombinant EARLI1 protein lacking its signal peptide was produced in Escherichia coli BL21(DE3) using isopropyl β-d-1-thiogalactopyranoside (IPTG) induction and the prokaryotic expression vector pET28a. Expression of EARLI1 was analyzed by Western blotting and the protein was purified using affinity chromatography. Recombinant EARLI1 protein was applied to fungal cultures of Saccharomyces cerevisiae, Botrytis cinerea and Fusarium oxysporum, and membrane permeability …

Resource‐Based Habitat Associations In A Neotropical Liana Community, James W. Dalling, Stefan A. Schnitzer, Claire Baldeck, Kyle E. Harms, Robert John, Scott A. Mangan, Elena Lobo, Joseph B. Yavitt, Stephen P. Hubbell

Biological Sciences Faculty Research and Publications

Summary

1. Lianas are a conspicuous element of many tropical forests, accounting for up to 40% of woody stem density and 20% of species richness in seasonal forests. However, lianas have seldom been surveyed at sufficiently large spatial scales to allow an assessment of the importance of habitat variables in structuring liana communities.

2. We compare the association patterns of 82 liana species and an equivalent sample of tree species on the 50 ha Forest Dynamics Project plot on Barro Colorado Island, Panama, with topographic habitat variables (high and low plateau, slope, swamp and streamside), and thirteen mapped soil chemical …

The Ranging Costs Of A Fallback Food: Liana Consumption Supplements Diet But Increases Foraging Effort In Howler Monkeys, Jacob C. Dunn, Norberto Asensio, Victor Arroyo-Rodriguez, Stefan A. Schnitzer, Jurgi Cristóbal‐Azkarate

Biological Sciences Faculty Research and Publications

Lianas are important components in the dynamics of tropical forests and represent fallback foods for some primates, yet little is known about their impact on primate ecology, behavior or fitness. Using 2 yr of field data, we investigated liana consumption and foraging effort in four groups of howler monkeys (two in bigger, more conserved forest fragments and two in smaller, less conserved fragments) to assess whether howler monkeys use lianas when and where food availability is scarce, and how liana consumption is related to foraging effort. Howler monkeys in smaller fragments spent more time consuming lianas and liana consumption was …

Methylene Blue Modulates Huntingtin Aggregation Intermediates And Is Protective In Huntington's Disease Models, Emily M. Sontag, Gregor P. Lotz, Namita Agrawal, Andrew Tran, Rebecca Aron, Guocheng Yang, Mihaela Necula, Alice Lau, Steven Finkbeiner, Charles G. Glabe, J. Lawrence Marsh, Paul J. Muchowski, Leslie M. Thompson

Biological Sciences Faculty Research and Publications

Huntington's disease (HD) is a devastating neurodegenerative disorder with no disease-modifying treatments available. The disease is caused by expansion of a CAG trinucleotide repeat and manifests with progressive motor abnormalities, psychiatric symptoms, and cognitive decline. Expression of an expanded polyglutamine repeat within the Huntingtin (Htt) protein impacts numerous cellular processes, including protein folding and clearance. A hallmark of the disease is the progressive formation of inclusions that represent the culmination of a complex aggregation process. Methylene blue (MB), has been shown to modulate aggregation of amyloidogenic disease proteins. We investigated whether MB could impact mutant Htt-mediated aggregation and neurotoxicity. MB …

Plasmodium Falciparum Ssb Tetramer Binds Single-Stranded Dna Only In A Fully Wrapped Mode, Edwin Antony, Alexander G. Kozlov, Binh Nguyen, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

The tetrameric Escherichia coli single-stranded DNA (ssDNA) binding protein (Ec-SSB) functions in DNA metabolism by binding to ssDNA and interacting directly with numerous DNA repair and replication proteins. Ec-SSB tetramers can bind ssDNA in multiple DNA binding modes that differ in the extent of ssDNA wrapping. Here, we show that the structurally similar SSB protein from the malarial parasite Plasmodium falciparum (Pf-SSB) also binds tightly to ssDNA but does not display the same number of ssDNA binding modes as Ec-SSB, binding ssDNA exclusively in fully wrapped complexes with site sizes of 52–65 nt/tetramer. Pf …

Plasmodium Falciparum Ssb Tetramer Wraps Single-Stranded Dna With Similar Topology But Opposite Polarity To E. Coli Ssb, Edwin Antony, Elizabeth A. Weiland, Sergey Korolev, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

Single-stranded DNA binding (SSB) proteins play central roles in genome maintenance in all organisms. Plasmodium falciparum, the causative agent of malaria, encodes an SSB protein that localizes to the apicoplast and likely functions in the replication and maintenance of its genome. P. falciparum SSB (Pf-SSB) shares a high degree of sequence homology with bacterial SSB proteins but differs in the composition of its C-terminus, which interacts with more than a dozen other proteins in Escherichia coli SSB (Ec-SSB). Using sedimentation methods, we show that Pf-SSB forms a stable homo-tetramer alone and when bound to …

Repeated Origin And Loss Of Adhesive Toepads In Geckos, Tony Gamble, Eli Greenbaum, Todd R. Jackman, Anthony P. Russell, Aaron M. Bauer

Biological Sciences Faculty Research and Publications

Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive …

The Mir-51 Family Of Micrornas Functions In Diverse Regulatory Pathways In Caenorhbditis Elegans, Allison L. Abbott, John L. Brenner, Benedict J. Kemp

Biological Sciences Faculty Research and Publications

The mir-51 family of microRNAs (miRNAs) in C. elegans are part of the deeply conserved miR-99/100 family. While loss of all six family members (mir-51-56) in C. elegans results in embryonic lethality, loss of individual mir-51 family members results in a suppression of retarded developmental timing defects associated with the loss of alg-1. The mechanism of this suppression of developmental timing defects is unknown. To address this, we characterized the function of the mir-51 family in the developmental timing pathway. We performed genetic analysis and determined that mir-51 family members regulate the developmental timing pathway in the L2 stage …

Novel Forests Maintain Ecosystem Processes After The Decline Of Native Tree Species, Joseph Mascaro, R. Flint Hughes, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

The positive relationship between species diversity (richness and evenness) and critical ecosystem functions, such as productivity, carbon storage, and nutrient cycling, is often used to predict the consequences of extinction. At regional scales, however, plant species richness is mostly increasing rather than decreasing because successful plant species introductions far outnumber extinctions. If these regional increases in richness lead to local increases in diversity, a reasonable prediction is that productivity, carbon storage, and nutrient cycling will increase following invasion, yet this prediction has rarely been tested empirically. We tested this prediction in novel forest communities dominated by introduced species (~90% basal …

Rcf1 And Rcf2, Members Of The Hypoxia-Induced Gene 1 Protein Family, Are Critical Components Of The Mitochondrial Cytochrome Bc1-Cytochrome Oxidase Supercomplex, Vera Strogolova, Andrew Furness, Micaela Robb-Mcgrath, Joshua Garlich, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

We report that Rcf1 (formerly Aim31), a member of the conserved hypoxia-induced gene 1 (Hig1) protein family, represents a novel component of the yeast cytochrome bc1-cytochrome c oxidase (COX) supercomplex. Rcf1 (respiratory supercomplex factor 1) partitions with the COX complex, and evidence that it may act as a bridge to the cytochrome bc1 complex is presented. Rcf1 interacts with the Cox3 subunit and can do so prior to their assembly into the COX complex. A close proximity of Rcf1 and members of the ADP/ATP carrier (AAC) family was also established. Rcf1 displays overlapping function with another Hig1-related protein, Rcf2 (formerly …

Microbial Biosafety Of Pilot-Scale Bioreactor Treating Mtbe And Tba-Contaminated Drinking Water Supply, Radomir Schmidt, David A. Klemme, Kate M. Scow, Krassimira R. Hristova

Biological Sciences Faculty Research and Publications

A pilot-scale sand-based fluidized bed bioreactor (FBBR) was utilized to treat both methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) from a contaminated aquifer. To evaluate the potential for re-use of the treated water, we tested for a panel of water quality indicator microorganisms and potential waterborne pathogens including total coliforms, Escherichia coli, Salmonella and Shigella spp., Campylobacter jejuni, Aeromonas hydrophila, Legionella pneumophila, Vibrio cholerae, Yersinia enterocolytica and Mycobacterium avium in both influent and treated waters from the bioreactor. Total bacteria decreased during FBBR treatment. E. coli, Salmonella and Shigella spp., C. jejuni, …

Phylogeny And Cryptic Diversity In Geckos (Phyllopezus; Phyllodactylidae; Gekkota) From South America’S Open Biomes, Tony Gamble, Guarino R. Colli, Miguel T. Rodrigues, Fernanda P. Werneck, Andrew M. Simons

Biological Sciences Faculty Research and Publications

The gecko genus Phyllopezus occurs across South America’s open biomes: Cerrado, Seasonally Dry Tropical Forests (SDTF, including Caatinga), and Chaco. We generated a multi-gene dataset and estimated phylogenetic relationships among described Phyllopezus taxa and related species. We included exemplars from both described Phyllopezus pollicaris subspecies, P. p. pollicaris and P. p. przewalskii. Phylogenies from the concatenated data as well as species trees constructed from individual gene trees were largely congruent. All phylogeny reconstruction methods showed Bogertia lutzae as the sister species of Phyllopezus maranjonensis, rendering Phyllopezus paraphyletic. We synonymized the monotypic genus Bogertia with Phyllopezus to maintain a …

Lianas Have A Greater Competitive Effect Than Trees Of Similar Biomass On Tropical Canopy Trees, Michael F. Tobin, Alexandra Wright, Scott A. Mangan, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Lianas (woody vines) reduce growth and survival of host trees in both temperate and tropical forests; however, the relative strength of liana‐tree competition in comparison to tree‐tree competition remains unexplored. When controlling for biomass, lianas may have greater competitive effects than trees because the unique morphology of lianas allows them to reach the forest canopy at relatively small stem diameters and deploy a substantial crown above their host. We tested the hypothesis that lianas have a greater negative effect on canopy trees than do trees of similar biomass with a liana‐ and tree sapling‐cutting experiment in a seasonal tropical moist …

Ornithine Decarboxylase Mrna Is Stabilized In An Mtorc1-Dependent Manner In Ras-Transformed Cells, Sofia Origanti, Shannon L. Nowotarski, Theresa D. Carr, Suzanne Sass-Kuhn, Lan Xiao, Jian-Ying Wang, Lisa M. Shantz

Biological Sciences Faculty Research and Publications

Upon Ras activation, ODC (ornithine decarboxylase) is markedly induced, and numerous studies suggest that ODC expression is controlled by Ras effector pathways. ODC is therefore a potential target in the treatment and prevention of Ras-driven tumours. In the present study we compared ODC mRNA translation profiles and stability in normal and Ras12V-transformed RIE-1 (rat intestinal epithelial) cells. While translation initiation of ODC increased modestly in Ras12V cells, ODC mRNA was stabilized 8-fold. Treatment with the specific mTORC1 [mTOR (mammalian target of rapamycin) complex 1] inhibitor rapamycin or siRNA (small interfering RNA) knockdown of mTOR destabilized the ODC mRNA, but rapamycin …

The Changes Of [Ca2+] In Sr And Ca2+ Release Flux During Fatiguing Activation Of Mouse Skeletal Muscle Fibers, Carlo Manno, Marisilius Mues, Robert H. Fitts, Oliver Griesbeck, Eduardo Rios

Biological Sciences Faculty Research and Publications

No abstract provided.

A Site Of Alcohol Action At The Nmda Receptor M3-M4 Domain Interface, Hong Ren, Yuanhao Zhao, D.S Dwyer, Robert W. Peoples

Biomedical Sciences Faculty Research and Publications

The N-methyl-D-aspartate (NMDA) glutamate receptor is a major target of ethanol in the brain. Previous studies have identified positions in the third and fourth membrane-associated (M) domains of the NMDA receptor GluN1 and GluN2A subunits that influence alcohol sensitivity. The structural model of the NMDA receptor, predicted from the structure of the related GluA2 subunit, indicates a close apposition of the alcohol-sensitive positions in M3 and M4 between the two subunit types. We investigated possible interactions between the M3 and M4 domain positions of the two subunit types affecting the ethanol sensitivity of the receptor by using dual substitution mutants. …

A Novel Alcohol-Sensitive Site In The M3 Domain Of The Nmda Receptor Glun2a Subunit, Hong Ren, Robert W. Peoples

Biomedical Sciences Faculty Research and Publications

Accumulating studies have demonstrated that the N-methyl-D-aspartate receptor is one of the most important targets of ethanol in the central nervous system. Previous studies from this laboratory have found that one position in the third (F637) and two positions in the fourth (M823 and A825) membrane-associated (M) domains of the N-methyl-D-aspartate receptor GluN2A subunit modulate alcohol action and ion channel gating. Using site-directed mutagenesis and whole-cell patch-clamp recording, we have found an additional position in M3 of the GluN2A subunit, F636, which significantly influences ethanol sensitivity and functionally interacts with F637. Tryptophan substitution at F636 significantly decreased the ethanol IC50, …

Developmental Expression Of Drop-Dead Is Required For Early Adult Survival And Normal Body Mass In Drosophila Melanogaster, Christine Lynn Sansone, Edward M. Blumenthal

Biological Sciences Faculty Research and Publications

In Drosophila melanogaster, mutations in the gene drop-dead (drd) result in early adult lethality, with flies dying within 2 weeks of eclosion. Additional phenotypes include neurodegeneration, tracheal defects, starvation, reduced body mass, and female sterility. The cause of early lethality and the function of the drd protein remain unknown. In the current study, the temporal profiles of drd expression required for adult survival and body mass regulation were investigated. Knockdown of drd expression by UAS-RNAi transgenes and rescue of drd expression on a drd mutant background by a UAS-drd transgene were controlled with the Heat Shock Protein …

Inhibitory Effects Of Arabidopsis Earli1 Against Botrytis Cinerea And Bradysia Difformis, Zhen Du, Dan Xu, Lan Li, Yao Shi, Michael Schläppi, Zi-Qin Xu

Biological Sciences Faculty Research and Publications

The aim of this study is to understand the function of EARLI1 in plants subjected to different biotic stresses using EARLI1 overexpressing (OX) and T-DNA knockout (KO) transgenic Arabidopsis lines. Higher levels of expression of EARLI1 in OX lines were confirmed by RT-PCR and Northern blot analysis. The full-length EARLI1 mRNA could not be detected by RT-PCR in KO lines, while only a shorter transcript could be found by RNA gel blotting. In wild-type Col-0 plants (Wt), EARLI1 could be induced by Botrytis cinerea and H₂O₂, indicating this gene might be involved in plant defense system …

Rna Unwinding By The Trf4/Air2/Mtr4 Polyadenylation (Tramp) Complex, Huijue Jia, Xuying Wang, James T. Anderson, Eckhard Jankowsky

Biological Sciences Faculty Research and Publications

Many RNA-processing events in the cell nucleus involve the Trf4/Air2/Mtr4 polyadenylation (TRAMP) complex, which contains the poly(A) polymerase Trf4p, the Zn-knuckle protein Air2p, and the RNA helicase Mtr4p. TRAMP polyadenylates RNAs designated for processing by the nuclear exosome. In addition, TRAMP functions as an exosome cofactor during RNA degradation, and it has been speculated that this role involves disruption of RNA secondary structure. However, it is unknown whether TRAMP displays RNA unwinding activity. It is also not clear how unwinding would be coordinated with polyadenylation and the function of the RNA helicase Mtr4p in modulating poly(A) addition. Here, we show …

The Versatile Molecular Complex Component Lc8 Promotes Several Distinct Steps Of Flagellar Assembly, Anjali Gupta, Dennis R. Diener, Priyanka Sivadas, Joel L. Rosenbaum, Pinfen Yang

Biological Sciences Faculty Research and Publications

LC8 is present in various molecular complexes. However, its role in these complexes remains unclear. We discovered that although LC8 is a subunit of the radial spoke (RS) complex in Chlamydomonas flagella, it was undetectable in the RS precursor that is converted into the mature RS at the tip of elongating axonemes. Interestingly, LC8 dimers bound in tandem to the N-terminal region of a spoke phosphoprotein, RS protein 3 (RSP3), that docks RSs to axonemes. LC8 enhanced the binding of RSP3 N-terminal fragments to purified axonemes. Likewise, the N-terminal fragments extracted from axonemes contained LC8 and putative spoke-docking proteins. Lastly, …

A Flagellar A-Kinase Anchoring Protein With Two Amphipathic Helices Forms A Structural Scaffold In The Radial Spoke Complex, Priyanka Sivadas, Jennifer M. Dienes, Martin St. Maurice, William D. Meek, Pinfen Yang

Biological Sciences Faculty Research and Publications

A-kinase anchoring proteins (AKAPs) contain an amphipathic helix (AH) that binds the dimerization and docking (D/D) domain, RIIa, in cAMP-dependent protein kinase A (PKA). Many AKAPs were discovered solely based on the AH–RIIa interaction in vitro. An RIIa or a similar Dpy-30 domain is also present in numerous diverged molecules that are implicated in critical processes as diverse as flagellar beating, membrane trafficking, histone methylation, and stem cell differentiation, yet these molecules remain poorly characterized. Here we demonstrate that an AKAP, RSP3, forms a dimeric structural scaffold in the flagellar radial spoke complex, anchoring through two distinct AHs, the RIIa …

Levels Of CaV1.2 L-Type Ca2+ Channels Peak In The First Two Weeks In Rat Hippocampus Whereas CaV1.3 Channels Steadily Increase Through Development, Audra A. Kramer, Nicholas E. Ingraham, Emily J. Sharpe, Michelle Mynlieff

Biological Sciences Faculty Research and Publications

Influx of calcium through voltage-dependent channels regulates processes throughout the nervous system. Specifically, influx through L-type channels plays a variety of roles in early neuronal development and is commonly modulated by G-protein-coupled receptors such as GABA_B receptors. Of the four isoforms of L-type channels, only Ca_v1.2 and Ca_v1.3 are predominately expressed in the nervous system. Both isoforms are inhibited by the same pharmacological agents, so it has been difficult to determine the role of specific isoforms in physiological processes. In the present study, Western blot analysis and confocal microscopy were utilized to study developmental expression …

A Coupled Experimental And Computational Approach To Quantify Deleterious Hemodynamics, Vascular Alterations, And Mechanisms Of Long-Term Morbidity In Response To Aortic Coarctati, Arjun Menon, David C. Wendell, Hongfeng Wang, Thomas J. Eddinger, Jeffrey M. Toth, Ronak Jashwant Dholakia, Paul M. Larsen, Eric S. Jensen, John F. Ladisa

Biomedical Engineering Faculty Research and Publications

Introduction

Coarctation of the aorta (CoA) is associated with morbidity despite treatment. Although mechanisms remain elusive, abnormal hemodynamics and vascular biomechanics are implicated. We present a novel approach that facilitates quantification of coarctation-induced mechanical alterations and their impact on vascular structure and function, without genetic or confounding factors.

Methods

Rabbits underwent thoracic CoA at 10 weeks of age (~ 9 human years) to induce a 20 mm Hg blood pressure (BP) gradient using permanent or dissolvable suture thereby replicating untreated and corrected CoA. Computational fluid dynamics (CFD) was performed using imaging and BP data at 32 weeks to quantify velocity, …

Roles Of Arg427 And Arg472 In The Binding And Allosteric Effects Of Acetyl Coa In Pyruvate Carboxylase, Abdussalam Adina-Zada, Chutima Sereerukb, Sarawut Jitrapakdee, Tonya N. Zeczycki, Martin St. Maurice, W. Wallace Cleland, John C. Wallace, Paul V. Attwood

Biological Sciences Faculty Research and Publications

Mutation of Arg427 and Arg472 in Rhizobium etli pyruvate carboxylase to serine or lysine greatly increased the activation constant (K_a) of acetyl CoA, with the increase being greater for the Arg472 mutants. These results indicate that while both these residues are involved in the binding of acetyl CoA to the enzyme, Arg472 is more important than Arg427. The mutations had substantially smaller effects on the k_cat for pyruvate carboxylation. Part of the effects of the mutations was to increase the K_m for MgATP and the K_a for activation by free Mg²⁺ determined at …