Biology Commons^™

Biomass And Toxicity Responses Of Poison Ivy (Toxicodendron Radicans) To Elevated Atmospheric Co2: Comment, Stefan A. Schnitzer, Ronald A. Londre, John Klironomos, Peter B. Reich

Biological Sciences Faculty Research and Publications

No abstract provided.

Degradation Of Hypomodified TrnaIMet In Vivo Involves Rna-Dependent Atpase Activity Of The Dexh Helicase Mtr4p, Xuying Wang, Huijue Jia, Eckhard Jankowsky, James T. Anderson

Biological Sciences Faculty Research and Publications

Effective turnover of many incorrectly processed RNAs in yeast, including hypomodified tRNA_i ^Met, requires the TRAMP complex, which appends a short poly(A) tail to RNA designated for decay. The poly(A) tail stimulates degradation by the exosome. The TRAMP complex contains the poly(A) polymerase Trf4p, the RNA-binding protein Air2p, and the DExH RNA helicase Mtr4p. The role of Mtr4p in RNA degradation processes involving the TRAMP complex has been unclear. Here we show through a genetic analysis that MTR4 is required for degradation but not for polyadenylation of hypomodified tRNA_i ^Met. A suppressor of the trm6-504 mutation …

Dimeric Heat Shock Protein 40 Binds Radial Spokes For Generating Coupled Power Strokes And Recovery Strokes Of 9 + 2 Flagella, Chun Yang, Heather A. Owen, Pinfen Yang

Biological Sciences Faculty Research and Publications

T-shape radial spokes regulate flagellar beating. However, the precise function and molecular mechanism of these spokes remain unclear. Interestingly, Chlamydomonas reinhardtii flagella lacking a dimeric heat shock protein (HSP) 40 at the spokehead–spokestalk juncture appear normal in length and composition but twitch actively while cells jiggle without procession, resembling a central pair (CP) mutant. HSP40⁻ cells begin swimming upon electroporation with recombinant HSP40. Surprisingly, the rescue doesn't require the signature DnaJ domain. Furthermore, the His-Pro-Asp tripeptide that is essential for stimulating HSP70 adenosine triphosphatase diverges in candidate orthologues, including human DnaJB13. Video microscopy reveals hesitance in bend initiation and …

Stressor- And Corticotropin Releasing Factor-Induced Reinstatement And Active Stress-Related Behavioral Responses Are Augmented Following Long-Access Cocaine Self-Administration By Rats, John R. Mantsch, David A. Baker, David M. Francis, Eric S. Katz, Michael A. Hoks, Joseph P. Serge

Biomedical Sciences Faculty Research and Publications

Rationale Stressful events during periods of drug abstinence likely contribute to relapse in cocaine-dependent individuals. Excessive cocaine use may increase susceptibility to stressor-induced relapse through alterations in brain corticotropin-releasing factor (CRF) responsiveness.

Objectives This study examined stressor- and CRF-induced cocaine seeking and other stress-related behaviors in rats with different histories of cocaine self-administration (SA).

Materials and methods Rats self-administered cocaine under short-access (ShA; 2 h daily) or long-access (LgA; 6 h daily) conditions for 14 days or were provided access to saline and were tested for reinstatement by a stressor (electric footshock), cocaine or an icv injection of CRF and …

The Spinobulbar System In Lamprey, James T. Buchanan, James F. Einum

Biological Sciences Faculty Research and Publications

Locomotor networks in the spinal cord are controlled by descending systems which in turn receive feedback signals from ascending systems about the state of the locomotor networks. In lamprey, the ascending system consists of spinobulbar neurons which convey spinal network signals to the two descending systems, the reticulospinal and vestibulospinal neurons. Previous studies showed that spinobulbar neurons consist of both ipsilaterally and contralaterally projecting cells distributed at all rostrocaudal levels of the spinal cord, though most numerous near the obex. The axons of spinobulbar neurons ascend in the ventrolateral spinal cord and brainstem to the caudal mesencephalon and within the …

Effect Of Ethanol On Microbial Community Structure And Function During Natural Attenuation Of Benzene, Toluene, And O-Xylene In A Sulfate-Reducing Aquifer, Kevin Feris, Doug Mackay, Nick De Sieyes, Irina Chakraborty, Murray Einarson, Krassimira R. Hristova, Kate M. Scow

Biological Sciences Faculty Research and Publications

Ethanol (EtOH) is a commonly used fuel oxygenate in reformulated gasoline and is an alternative fuel and fuel supplement. Effects of EtOH release on aquifer microbial ecology and geochemistry have not been well characterized in situ. We performed a controlled field release of petroleum constituents (benzene (B), toluene (T), o-xylene (o-X) at ∼1–3 mg/L each) with and without EtOH (∼500 mg/L). Mixed linear modeling (MLM) assessed effects on the microbial ecology of a naturally sulfidic aquifer and how the microbial community affected B, T, and o-X plume lengths and aquifer geochemistry. Changes in microbial community structure …

Mitochondrial Biogenesis: Is An Old Dog Still Teaching Us New Tricks? Meeting On The Assembly Of The Mitochondrial Respiratory Chain, Rosemary A. Stuart, Peter Rehling

Biological Sciences Faculty Research and Publications

No abstract provided.

Amp-Activated Protein Kinase Is Involved In Hormone-Induced Mouse Oocyte Meiotic Maturation In Vitro, Jing Chen, Stephen M. Downs

Biological Sciences Faculty Research and Publications

We have previously shown that AMP-activated protein kinase (AMPK) can induce the resumption of meiosis in mouse oocytes maintained in meiotic arrest in vitro. The present study was carried out to determine whether AMPK activation is involved in hormone-induced maturation. Follicle-stimulating hormone (FSH) and the EGF-like peptide, amphiregulin (AR), are potent inducers of maturation in cumulus cell-enclosed oocytes (CEO). Within 3 h of FSH treatment, phospho-acetyl CoA carboxylase (ACC) levels were increased in germinal vesicle (GV)-stage oocytes when compared to non-stimulated controls and remained elevated throughout 9 h of culture, indicating AMPK activation. A similar response to AR was observed …

Tertiary Climate Change And The Diversification Of The Amazonian Gecko Genus Gonatodes (Sphaerodactylidae, Squamata), Tony Gamble, Andrew M. Simons, Guarino R. Colli, Laurie J. Vitt

Biological Sciences Faculty Research and Publications

The genus Gonatodes is a monophyletic group of small-bodied, diurnal geckos distributed across northern South America, Central America, and the Caribbean. We used fragments of three nuclear genes (RAG2, ACM4, and c-mos) and one mitochondrial gene (16S) to estimate phylogenetic relationships among Amazonian species of Gonatodes. We used Penalized Likelihood to estimate timing of diversification in the genus. Most cladogenesis occurred in the Oligocene and early Miocene and coincided with a burst of diversification in other South American animal groups including mollusks, birds, and mammals. The Oligocene and early Miocene were periods dominated by …

Cold Responsive Earli1 Type Hyprps Improve Freezing Survival Of Yeast Cells And Form Higher Order Complexes In Plants, Yi Zhang, Michael Schläppi

Biological Sciences Faculty Research and Publications

Plants have large families of proteins sharing a conserved eight-cysteine-motif (8CM) domain. The biological functions of these proteins are largely unknown. EARLI1 is a cold responsive Arabidopsis gene that encodes a hybrid proline-rich protein (HyPRP) with a three-domain architecture: a putative signal peptide at the N-terminus, a proline-rich domain (PRD) in the middle, and an 8CM domain at the C-terminus. We report here that yeast cells expressing different EARLI1 genes had significantly higher rates of freezing survival than empty-vector transformed controls. Arabidopsis plants with knocked down EARLI1 genes had an increased tendency for freezing-induced cellular damage. EARLI1-GFP Fluorescence in …

Most Caenorhabditis Elegans Micrornas Are Individually Not Essential For Development Or Viability, Eric A. Miska, Ezequiel Alvarez-Saavedra, Allison L. Abbott, Nelson C. Lau, Andrew B. Hellman, Shannon M. Mcgonagle, David P. Bartel, Victor R. Ambros, H. Robert Horvitz

Biological Sciences Faculty Research and Publications

MicroRNAs (miRNAs), a large class of short noncoding RNAs found in many plants and animals, often act to post-transcriptionally inhibit gene expression. We report the generation of deletion mutations in 87 miRNA genes in Caenorhabditis elegans, expanding the number of mutated miRNA genes to 95, or 83% of known C. elegans miRNAs. We find that the majority of miRNAs are not essential for the viability or development of C. elegans, and mutations in most miRNA genes do not result in grossly abnormal phenotypes. These observations are consistent with the hypothesis that there is significant functional redundancy among miRNAs …

A Mutant Dec-1 Transgene Induces Dominant Female Sterility In Drosophila Melanogaster, Daniel K. Spangenberg, Gail L. Waring

Biological Sciences Faculty Research and Publications

The Drosophila dec-1 gene produces three proproteins required for female fertility and eggshell assembly. The three proproteins are distinguished by their C termini. Fc106, the most abundant proprotein, is cleaved within the vitelline membrane to three mature derivatives in a developmentally regulated manner. To define sequences within fc106 that are critical for its function, we created wild-type and mutant versions of an fc106 cDNA transgene. The functional consequences of the mutations were assessed in dec-1⁴, a female-sterile splicing mutant that does not produce the fc106 isoform. The fertility of dec-1⁴ females was restored by the introduction of …

The Chlamydomonas Genome Reveals The Evolution Of Key Animal And Plant Functions, Sabeeha S. Merchant, Simon E. Prochnik, Olivier Vallon, Elizabeth H. Harris, Steven J. Karpowicz, George B. Witman, Astrid Terry, Asaf Salamov, Lillian K. Fritz-Laylin, Laurence Maréchal-Drouard, Wallace F. Marshall, Liang-Hu Qu, David R. Nelson, Anton A. Sanderfoot, Martin H. Spalding, Vladimir V. Kapitonov, Qinghu Ren, Patrick Ferris, Erika Lindquist, Harris Shapiro, Susan M. Lucas, Jane Grimwood, Jeremy Schmutz, Pierre Cardol, Heriberto Cerutti, Guillaume Chanfreau, Chun-Long Chen, Valerie Cognat, Martin T. Croft, Rachel Dent, Susan Dutcher, Emilio Fernández, Hideya Fukuzawa, David González-Ballester, Diego González-Halphen, Armin Hallmann, Marc Hanikenne, Michael Hippler, William Inwood, Kamel Jabbari, Ming Kalanon, Richard Kuras, Paul A. Lefebvre, Stéphane D. Lemaire, Alexey V. Lobanov, Martin Lohr, Andrea Manuell, Iris Meier, Laurens Mets, Maria Mittag, Telsa Mittelmeier, James V. Moroney, Jeffrey Moseley, Carolyn Napoli, Aurora M. Nedelcu, Krishna Niyogi, Sergey V. Novoselov, Ian T. Paulsen, Greg Pazour, Saul Purton, Jean-Philippe Ral, Diego Mauricio Riaño-Pachón, Wayne Riekhof, Linda Rymarquis, Michael Schroda, David Stern, James Umen, Robert Willows, Nedra Wilson, Sara Lana Zimmer, Jens Allmer, Janneke Balk, Katerina Bisova, Chong-Jian Chen, Mark Elias, Karla Gendler, Charles Hauser, Mary Rose Lamb, Heidi Ledford, Joanne C. Long, Jun Minagawa, M. Dudley Page, Junmin Pan, Wirulda Pootakham, Sanja Roje, Annkatrin Rose, Eric Stahlberg, Aimee M. Terauchi, Pinfen Yang, Steven Ball, Chris Bowler, Carol L. Dieckmann, Vadim N. Gladyshev, Pamela Green, Richard Jorgensen, Stephen Mayfield, Bernd Mueller-Roeber, Sathish Rajamani, Richard T. Sayre, Peter Brokstein, Inna Dubchak, David Goodstein, Leila Hornick, Y. Wayne Huang, Jinal Jhaveri, Yigong Luo, Diego Martinez, Wing Chi Abby Ngau, Bobby Otillar, Alexander Poliakov, Aaron Porter, Lukasz Szajkowski, Gregory Werner, Kemin Zhou, Igor V. Grigoriev, Daniel S. Rokhsar, Arthur R. Grossman

Biological Sciences Faculty Research and Publications

Chlamydomonas reinhardtii is a unicellular green alga whose lineage diverged from land plants over 1 billion years ago. It is a model system for studying chloroplast-based photosynthesis, as well as the structure, assembly, and function of eukaryotic flagella (cilia), which were inherited from the common ancestor of plants and animals, but lost in land plants. We sequenced the ∼120-megabase nuclear genome of Chlamydomonas and performed comparative phylogenomic analyses, identifying genes encoding uncharacterized proteins that are likely associated with the function and biogenesis of chloroplasts or eukaryotic flagella. Analyses of the Chlamydomonas genome advance our understanding of the ancestral eukaryotic cell, …

Evidence For Gondwanan Vicariance In An Ancient Clade Of Gecko Lizards, Tony Gamble, Aaron M. Bauer, E. Greenbaum, Todd R. Jackman

Biological Sciences Faculty Research and Publications

Aim

Geckos (Reptilia: Squamata), due to their great age and global distribution, are excellent candidates to test hypotheses of Gondwanan vicariance against post‐Gondwanan dispersal. Our aims are: to generate a phylogeny of the sphaerodactyl geckos and their closest relatives; evaluate previous phylogenetic hypotheses of the sphaerodactyl geckos with regard to the other major gecko lineages; and to use divergence date estimates to inform a biogeographical scenario regarding Gondwanan relationships and assess the roles of vicariance and dispersal in shaping the current distributions of the New World sphaerodactyl geckos and their closest Old World relatives.

Location

Africa, Asia, Europe, South America, …

The Exosome Subunit Rrp44 Plays A Direct Role In Rna Substrate Recognition, Claudia Schneider, James T. Anderson, David Tollervey

Biological Sciences Faculty Research and Publications

The exosome plays key roles in RNA maturation and surveillance, but it is unclear how target RNAs are identified. We report the functional characterization of the yeast exosome component Rrp44, a member of the RNase II family. Recombinant Rrp44 and the purified TRAMP polyadenylation complex each specifically recognized tRNA_i^Met lacking a single m¹A₅₈ modification, even in the presence of a large excess of total tRNA. This tRNA is otherwise mature and functional in translation in vivo but is presumably subtly misfolded. Complete degradation of the hypomodified tRNA required both Rrp44 and the poly(A) polymerase activity …

Change In Nutritional Status Modulates The Abundance Of Critical Pre-Initiation Intermediate Complexes During Translation Initiation In Vivo, Chingakham Ranjit Singh, Tsuyoshi Udagawa, Bumjun Lee, Sarah Wassink, Hei He, Yasufumi Yamamoto, James T. Anderson, Graham D. Pavitt, Katsura Asano

Biological Sciences Faculty Research and Publications

In eukaryotic translation initiation, eIF2∙GTP–Met-tRNA_i^Met ternary complex (TC) interacts with eIF3–eIF1–eIF5 complex to form the multifactor complex (MFC), while eIF2∙GDP associates with eIF2B for guanine nucleotide exchange. Gcn2p phosphorylates eIF2 to inhibit eIF2B. Here we evaluate the abundance of eIFs and their pre-initiation intermediate complexes in gcn2 deletion mutant grown under different conditions. We show that ribosomes are three times as abundant as eIF1, eIF2 and eIF5, while eIF3 is half as abundant as the latter three and hence, the limiting component in MFC formation. By quantitative immunoprecipitation, we estimate that ∼ 15% of …

A Science Club Takes Action, Olivia Ledee, Anna Mosser, Tony Gamble, Greg Childs, Karen Oberhauser

Biological Sciences Faculty Research and Publications

No abstract provided.

Rhizobium Etli Ce3 Bacteroid Lipopolysaccharides Are Structurally Similar But Not Identical To Those Produced By Cultured Ce3 Bacteria, Wim D'Haeze, Christine Leoff, Glenn Freshour, K. Dale Noel, Russell W. Carlson

Biological Sciences Faculty Research and Publications

Rhizobium etli CE3 bacteroids were isolated from Phaseolus vulgaris root nodules. The lipopolysaccharide (LPS) from the bacteroids was purified and compared with the LPS from laboratory-cultured R. etli CE3and from cultures grown in the presence of anthocyanin. Comparisons were made of the O-chain polysaccharide, the core oligosaccharide, and the lipid A. Although LPS from CE3 bacteria and bacteroids are structurally similar, it was found that bacteroid LPS had specific modifications to both the O-chain polysaccharide and lipid A portions of their LPS. Cultures grown with anthocyanin contained modifications only to the O-chain polysaccharide. The changes to the O-chain polysaccharide consisted …

Preferential Myosin Heavy Chain Isoform B Expression May Contribute To The Faster Velocity Of Contraction In Veins Versus Arteries, Catherine M. Rondelli, Irina T. Szasz, Anas Kayal, Keshari Thakali, Ralph E. Watson, Arthur S. Rovner, Thomas J. Eddinger, Gregory D. Fink, Stephanie W. Watts

Biological Sciences Faculty Research and Publications

Smooth muscle myosin heavy chains occur in 2 isoforms, SMA (slow) and SMB (fast). We hypothesized that the SMB isoform is predominant in the faster-contracting rat vena cava compared to thoracic aorta. We compared the time to half maximal contraction in response to a maximal concentration of endothelin-1 (ET-1; 100 nM), potassium chloride (KCl; 100 mM) and norepinephrine (NE; 10 µM). The time to half maximal contraction was shorter in the vena cava compared to aorta (aorta: ET-1 = 235.8 ± 13.8 s, KCl = 140.0 ± 33.3 s, NE = 19.8 ± 2.7 s; vena cava: ET-1 = 121.8 …

Myosin Ii Isoforms In Smooth Muscle: Heterogeneity And Function, Thomas J. Eddinger, Daniel P. Meer

Biological Sciences Faculty Research and Publications

Both smooth muscle (SM) and nonmuscle class II myosin molecules are expressed in SM tissues comprising hollow organ systems. Individual SM cells may express one or more of multiple myosin II isoforms that differ in myosin heavy chain (MHC) and myosin light chain (MLC) subunits. Although much has been learned, the expression profiles, organization within contractile filaments, localization within cells, and precise roles in various contractile functions of these different myosin molecules are still not well understood. However, data supporting unique physiological roles for certain isoforms continues to build. Isoform differences located in the S1 head region of the MHC …

Oxa1 Directly Interacts With Atp9 And Mediates Its Assembly Into The Mitochondrial F1FO-Atp Synthase Complex, Lixia Jia, Mary Kathryn Dienhart, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

The yeast Oxa1 protein is involved in the biogenesis of the mitochondrial oxidative phosphorylation (OXPHOS) machinery. The involvement of Oxa1 in the assembly of the cytochrome oxidase (COX) complex, where it facilitates the cotranslational membrane insertion of mitochondrially encoded COX subunits, is well documented. In this study we have addressed the role of Oxa1, and its sequence-related protein Cox18/Oxa2, in the biogenesis of the F₁F_o-ATP synthase complex. We demonstrate that Oxa1, but not Cox18/Oxa2, directly supports the assembly of the membrane embedded F_o-sector of the ATP synthase. Oxa1 was found to physically interact with …

Ras Transformation Of Rie-1 Cells Activates Cap-Independent Translation Of Ornithine Decarboxylase: Regulation By The Raf/Mek/Erk And Phosphatidylinositol 3-Kinase Pathways, Sofia Origanti, Lisa M. Shantz

Biological Sciences Faculty Research and Publications

Ornithine decarboxylase (ODC) is the first and generally rate-limiting enzyme in polyamine biosynthesis. Deregulation of ODC is critical for oncogenic growth, and ODC is a target of Ras. These experiments examine translational regulation of ODC in RIE-1 cells, comparing untransformed cells with those transformed by an activated Ras12V mutant. Analysis of the ODC 5′ untranslated region (5′UTR) revealed four splice variants with the presence or absence of two intronic sequences. All four 5′UTR species were found in both cell lines; however, variants containing intronic sequences were more abundant in Ras-transformed cells. All splice variants support internal ribosome entry site …

The Deleterious Effects Of Bed Rest On Human Skeletal Muscle Fibers Are Exacerbated By Hypercortisolemia And Ameliorated By Dietary Supplementation, Robert H. Fitts, Janell Romatowski, Jim R. Peters, D. Paddon-Jones, R. R. Wolfe, A. A. Ferrando

Biological Sciences Faculty Research and Publications

Prolonged inactivity associated with bed rest in a clinical setting or spaceflight is frequently associated with hypercortisolemia and inadequate caloric intake. Here, we determined the effect of 28 days of bed rest (BR); bed rest plus hypercortisolemia (BRHC); and bed rest plus essential amino acid (AA) and carbohydrate (CHO) supplement (BRAA) on the size and function of single slow- and fast-twitch muscle fibers. Supplementing meals, the BRAA group consumed 16.5 g essential amino acids and 30 g sucrose at 1100, 1600, and 2100 h, and the BRHC subjects received 5 daily doses of 10–15 mg of oral hydrocortisone sodium succinate …

Is Oak Establishment In Old‐Fields And Savanna Openings Context Dependent?, Ian A. Dickie, Stefan A. Schnitzer, P. B. Reich, S. E. Hobbie

Biological Sciences Faculty Research and Publications

1. Multiple factors are known to influence tree seedling establishment, yet the degree to which these factors depend on each other and on spatial context is largely unknown. We examined the influence of herbaceous competition and water and nitrogen limitations on tree seedling establishment as functions of distance from trees (within‐site spatial context) and site history (between‐site spatial context; as old‐fields vs. savanna openings).
2. We grew Quercus ellipsoidalis E.J. Hill (pin oak) and Q. macrocarpa Michx. (bur oak) seedlings for 3 years in abandoned agricultural fields and savannas in central Minnesota, USA, near and distant from adult oak trees, with and …

Frigida Like 2 Is A Functional Allele In Landsberg Erecta And Compensates For A Nonsense Allele Of Frigida Like 1, Michael Schläppi

Biological Sciences Faculty Research and Publications

The Landsberg erecta (Ler) accession of Arabidopsis (Arabidopsis thaliana) has a weak allele of the floral inhibitor FLOWERING LOCUS C (FLC). FLC-Ler is weakly up-regulated by the active San Feliu-2 (Sf2) allele of FRIGIDA (FRI-Sf2), resulting in a moderately late-flowering phenotype. By contrast, the Columbia (Col) allele of FLC is strongly up-regulated by FRI-Sf2, resulting in a very late-flowering phenotype. In Col, the FRI-related gene FRI LIKE 1 (FRL1) is required for FRI-mediated upregulation of FLC. It is shown here that in Ler …

The Distribution Of Lianas And Their Change In Abundance In Temperate Forests Over The Past 45 Years, Ronald A. Londre, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Lianas (woody vines) are an important and dynamic component of many forests throughout the world, and increases in CO₂, mean winter temperature, and forest fragmentation may promote their growth and proliferation in temperate forests. In this study, we used a 45‐year data set to test the hypothesis that lianas have increased in abundance and basal area in the interiors of 14 deciduous temperate forests in Wisconsin (USA) since 1959. We also censused woody plants along a gradient from the forest edge to the interior in seven of these forests to test the hypothesis that the abundance of lianas …

Adherens Junction-Associated Protein Distribution Differs In Smooth Muscle Tissue And Acutely Isolated Cells, Thomas J. Eddinger, Jessen D. Schiebout, Darl R. Swartz

Biological Sciences Faculty Research and Publications

This study was designed to examine how smooth muscle (SM) cell (SMC) isolation affects the distribution of some adherens junction (AJ) complex-associated proteins. Immunofluorescence procedures for identifying protein distribution were used on gastrointestinal and tracheal SM tissues and freshly isolated SMCs from dogs and rabbits. As confirmed by force measurements, relaxation, Ca²⁺ depletion, and cholinergic activation of SM tissues do not cause significant redistribution of the AJ-associated proteins vinculin, talin, or fibronectin away from the plasma membrane. Unlike SMCs in tissue, freshly isolated SMCs show a variable peripheral/ cytoplasmic vinculin and talin distribution that is not altered by activation. …

Spinobulbar Neurons In Lamprey: Cellular Properties And Synaptic Interactions, James F. Einum, James T. Buchanan

Biological Sciences Faculty Research and Publications

An in vitro preparation of the nervous system of the lamprey, a lower vertebrate, was used to characterize the properties of spinal neurons with axons projecting to the brain stem [i.e., spinobulbar (SB) neurons)]. To identify SB neurons, extracellular electrodes on each side of the spinal cord near the obex recorded the axonal spikes of neurons impaled with sharp intracellular microelectrodes in the rostral spinal cord. The ascending spinal neurons (n = 144) included those with ipsilateral (iSB) (63/144), contralateral (cSB) (77/144), or bilateral (bSB) (4/144) axonal projections to the brain stem. Intracellular injection of biocytin revealed that the …

Resistance To Pressure-Induced Dilatation In Femoral But Not Saphenous Artery: Physiological Role Of Latch?, Christopher Call, Shaojie Han, John E. Speich, Thomas J. Eddinger, Paul H. Ratz

Biological Sciences Faculty Research and Publications

We recently determined that the ability of the femoral artery (FA) to maintain higher levels of tonic isometric stress compared with the saphenous artery (SA) was due to differential expression of motor proteins permitting latch-bridge formation in FA and not SA. Arteries under pressure in vivo are not constrained to contract isometrically. Thus the significance of latch-bridge formation in arterial physiology remains to be determined. To address this translational question, diameter changes of pressurized FA and SA were compared. The reduction in lumen diameter induced by KCl at 80 mmHg (isobaric active constriction; IAC) was greater at 30 s than …

Low Cell Ph Depresses Peak Power In Rat Skeletal Muscle Fibres At Both 30°C And 15°C: Implications For Muscle Fatigue, Shannon T. Knuth, H. L. W. Dave, Jim R. Peters, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Historically, an increase in intracellular H⁺ (decrease in cell pH) was thought to contribute to muscle fatigue by direct inhibition of the cross-bridge leading to a reduction in velocity and force. More recently, due to the observation that the effects were less at temperatures closer to those observed in vivo, the importance of H⁺ as a fatigue agent has been questioned. The purpose of this work was to re-evaluate the role of H⁺ in muscle fatigue by studying the effect of low pH (6.2) on force, velocity and peak power in rat fast-and slow-twitch muscle fibres …