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Articles 721 - 750 of 1010

Full-Text Articles in Biology

Protransglutaminase (Factor Xiii) Mediated Crosslinking Of Fibrinogen And Fibrin, Kevin R. Siebenlist, David A. Meh, Michael W. Mosesson Jan 2001

Protransglutaminase (Factor Xiii) Mediated Crosslinking Of Fibrinogen And Fibrin, Kevin R. Siebenlist, David A. Meh, Michael W. Mosesson

Biological Sciences Faculty Research and Publications

No abstract provided.

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Effects Of Depolarization And Low Intracellular Ph On Charge Movement Currents Of Frog Skeletal Muscle Fibers, Edward Michael Balog, Robert H. Fitts Jan 2001

Effects Of Depolarization And Low Intracellular Ph On Charge Movement Currents Of Frog Skeletal Muscle Fibers, Edward Michael Balog, Robert H. Fitts

Biological Sciences Faculty Research and Publications

The low intracellular pH and membrane depolarization associated with repeated skeletal muscle stimulation could impair the function of the transverse tubular (t tubule) voltage sensor and result in a decreased sarcoplasmic reticulum Ca2+ release and muscle fatigue. We therefore examined the effects of membrane depolarization and low intracellular pH on the t-tubular charge movement. Fibers were voltage clamped in a double Vaseline gap, at holding potential (HP) of 290 or 260 mV, and studied at an internal pH of 7.0 and 6.2. Decreasing intracellular pH did not significantly alter the maximum amount of charge moved, transition voltage, or steepness …

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Biennialism And Vernalization-Promoted Flowering In Hyoscyamus Niger: A Comparison With Arabidopsis, Michael Schläppi, Monica Patel Jan 2001

Biennialism And Vernalization-Promoted Flowering In Hyoscyamus Niger: A Comparison With Arabidopsis, Michael Schläppi, Monica Patel

Biological Sciences Faculty Research and Publications

There are genetic similarities between the biennial growth habit of Hyoscyamus niger (H. niger) and winter annual ecotypes of Arabidopsis thaliana, including the response to demethylating agents. One focus of our research group at Marquette is to determine whether FLOWERING LOCUS C (FLC) homologs or FLC-related MADS-box genes are involved in biennialism of H. niger. This review also summarizes our initial characterization of expression profiles of 4 groups of H. niger MADS-box genes. Our results suggest that B-class floral homeotic gene homologs of H. niger are differentially expressed in flowers of annual and …

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A Gene Expression Screen Identifies Earli1 As A Novel Vernalization-Responsive Gene In Arabidopsis Thaliana, Richard K. Wilkosz, Michael Schläppi Dec 2000

A Gene Expression Screen Identifies Earli1 As A Novel Vernalization-Responsive Gene In Arabidopsis Thaliana, Richard K. Wilkosz, Michael Schläppi

Biological Sciences Faculty Research and Publications

Vernalization promotes early flowering in late ecotypes of Arabidopsis thaliana. The mechanisms of vernalization are poorly understood. A subtractive hybridization approach was used to isolate vernalization-responsive genes from a late-flowering ecotype of Arabidopsis thaliana based on the premise that transcript levels of such genes would increase with cold treatment and remain high even after removal of the vernalization stimulus. EARLI1 is the first Arabidopsis gene shown to be stably activated by vernalization. The abundance of its RNA is progressively elevated by vernalization and remains high for at least 20 days at room temperature. The basal level of EARLI1 RNA …

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Spaceflight Effects On Single Skeletal Muscle Fiber Function In The Rhesus Monkey, Robert H. Fitts, Dominique Desplanches, Janell Romatowski, Jeffrey J. Widrick Nov 2000

Spaceflight Effects On Single Skeletal Muscle Fiber Function In The Rhesus Monkey, Robert H. Fitts, Dominique Desplanches, Janell Romatowski, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 ± 1, 46 ± 2, and 59 ± 2 µm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 ± 0.01 to 0.31 ± 0.02 …

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A Family Of Developmentally Excised Dna Elements In Tetrahymena Is Under Selective Pressure To Maintain An Open Reading Frame Encoding An Integrase-Like Protein, Jill A. Gershan, Kathleen M. Karrer Nov 2000

A Family Of Developmentally Excised Dna Elements In Tetrahymena Is Under Selective Pressure To Maintain An Open Reading Frame Encoding An Integrase-Like Protein, Jill A. Gershan, Kathleen M. Karrer

Biological Sciences Faculty Research and Publications

Tlr1 is a member of a family of ~20-30 DNA elements that undergo developmentally regulated excision during formation of the macronucleus in the ciliated protozoan Tetrahymena. Analysis of sequence internal to the right boundary of Tlr1 revealed the presence of a 2 kb open reading frame (ORF) encoding a deduced protein with similarity to retrotransposon integrases. The ORFs of five unique clones were sequenced. The ORFs have 98% sequence conservation and align without frameshifts, although one has an additional trinucleotide at codon 561. Nucleotide changes among the five clones are highly non-random with respect to the position in the …

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Selection Of Alternative 5′ Splice Sites: Role Of U1 Snrnp And Models For The Antagonistic Effects Of Sf2/Asf And Hnrnp A1, Ian C. Eperon, Olga V. Makarova, Akila Mayeda, Stephen Munroe, Javier F. Cáceres, Daniel G. Hayward, Adrian R. Krainer Nov 2000

Selection Of Alternative 5′ Splice Sites: Role Of U1 Snrnp And Models For The Antagonistic Effects Of Sf2/Asf And Hnrnp A1, Ian C. Eperon, Olga V. Makarova, Akila Mayeda, Stephen Munroe, Javier F. Cáceres, Daniel G. Hayward, Adrian R. Krainer

Biological Sciences Faculty Research and Publications

The first component known to recognize and discriminate among potential 5′ splice sites (5′SSs) in pre-mRNA is the U1 snRNP. However, the relative levels of U1 snRNP binding to alternative 5′SSs do not necessarily determine the splicing outcome. Strikingly, SF2/ASF, one of the essential SR protein-splicing factors, causes a dose-dependent shift in splicing to a downstream (intron-proximal) site, and yet it increases U1 snRNP binding at upstream and downstream sites simultaneously. We show here that hnRNP A1, which shifts splicing towards an upstream 5′SS, causes reduced U1 snRNP binding at both sites. Nonetheless, the importance of U1 snRNP binding is …

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Varying The Abundance Of O Antigen In Rhizobium Etli And Its Effect On Symbiosis With Phaseolus Vulgaris, K. Dale Noel, Lennart Scott Forsberg, Russell W. Carlson Oct 2000

Varying The Abundance Of O Antigen In Rhizobium Etli And Its Effect On Symbiosis With Phaseolus Vulgaris, K. Dale Noel, Lennart Scott Forsberg, Russell W. Carlson

Biological Sciences Faculty Research and Publications

Judged by migration of its lipopolysaccharide (LPS) in gel electrophoresis, the O antigen of Rhizobium etli mutant strain CE166 was apparently of normal size. However, its LPS sugar composition and staining of the LPS bands after electrophoresis indicated that the proportion of its LPS molecules that possessed O antigen was only 40% of the wild-type value. Its LPS also differed from the wild type by lacking quinovosamine (2-amino-2,6-dideoxyglucose). Both of these defects were due to a single genetic locus carrying a Tn5 insertion. The deficiency in O-antigen amount, but not the absence of quinovosamine, was suppressed by transferring into …

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Have We Forgotten The Forest Because Of The Trees?, Stefan A. Schnitzer, Walter P. Carson Sep 2000

Have We Forgotten The Forest Because Of The Trees?, Stefan A. Schnitzer, Walter P. Carson

Biological Sciences Faculty Research and Publications

No abstract provided.

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Uncharged Trna Activates Gcn2 By Displacing The Protein Kinase Moiety From A Bipartite Trna-Binding Domain, Jinsheng Dong, Hongfang Qiu, Minerva Garcia-Barrio, James T. Anderson, Alan G. Hinnebusch Aug 2000

Uncharged Trna Activates Gcn2 By Displacing The Protein Kinase Moiety From A Bipartite Trna-Binding Domain, Jinsheng Dong, Hongfang Qiu, Minerva Garcia-Barrio, James T. Anderson, Alan G. Hinnebusch

Biological Sciences Faculty Research and Publications

Protein kinase GCN2 regulates translation in amino acid–starved cells by phosphorylating eIF2. GCN2 contains a regulatory domain related to histidyl-tRNA synthetase (HisRS) postulated to bind multiple deacylated tRNAs as a general sensor of starvation. In accordance with this model, GCN2 bound several deacylated tRNAs with similar affinities, and aminoacylation of tRNAPhe weakened its interaction with GCN2. Unexpectedly, the C-terminal ribosome binding segment of GCN2 (C-term) was required in addition to the HisRS domain for strong tRNA binding. A combined HisRS+C-term segment bound to the isolated protein kinase (PK) domain in vitro, and tRNA impeded this interaction. An activating mutation …

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Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick Aug 2000

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity …

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Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick Aug 2000

Physiology Of A Microgravity Environment Invited Review: Microgravity And Skeletal Muscle, Robert H. Fitts, Danny R. Riley, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity …

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The Impact Of Lianas On Tree Regeneration In Tropical Forest Canopy Gaps: Evidence For An Alternative Pathway Of Gap‐Phase Regeneration, Stefan A. Schnitzer, James W. Dalling, Walter P. Carson Aug 2000

The Impact Of Lianas On Tree Regeneration In Tropical Forest Canopy Gaps: Evidence For An Alternative Pathway Of Gap‐Phase Regeneration, Stefan A. Schnitzer, James W. Dalling, Walter P. Carson

Biological Sciences Faculty Research and Publications

1 Regeneration in forest canopy gaps is thought to lead invariably to the rapid recruitment and growth of trees and the redevelopment of the canopy. Our observations, however, suggest that an alternate successional pathway is also likely, whereby gap‐phase regeneration is dominated by lianas and stalled in a low‐canopy state for many years. We investigated gap‐phase regeneration in an old‐growth tropical forest on Barro Colorado Island (BCI) in Panama to test the following two hypotheses: (i) many gaps follow a pathway in which they remain at a low canopy height and are dominated by lianas and (ii) the paucity of …

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Expression Of Smooth Muscle Myosin Light Chain 17 And Unloaded Shortening In Single Smooth Muscle Cells, Thomas J. Eddinger, A. A. Korwek, Daniel P. Meer, Jennifer J. Sherwood Jun 2000

Expression Of Smooth Muscle Myosin Light Chain 17 And Unloaded Shortening In Single Smooth Muscle Cells, Thomas J. Eddinger, A. A. Korwek, Daniel P. Meer, Jennifer J. Sherwood

Biological Sciences Faculty Research and Publications

These experiments were performed to test the hypotheses that myosin light chain 17 (MLC17) a and b isoform expression varies between individual vascular smooth muscle (SM) cells and that their expression correlates with cell unloaded shortening velocity. Single SM cells isolated from rabbit aorta and carotid arteries were used to measure unloaded shortening velocity and subsequently were analyzed via RT-PCR for MLC17 a and b mRNA ratio. The MLC17b/a mRNA and protein ratios from adjacent tissue sections correlate very well (R2 = 0.68), allowing use of the mRNA ratio to predict the protein ratio. …

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A Developmentally Regulated Deletion Element With Long Terminal Repeats Has Cis-Acting Sequences In The Flanking Dna, Namrata S. Patil, Kathleen M. Karrer Mar 2000

A Developmentally Regulated Deletion Element With Long Terminal Repeats Has Cis-Acting Sequences In The Flanking Dna, Namrata S. Patil, Kathleen M. Karrer

Biological Sciences Faculty Research and Publications

Approximately 6000 specific DNA deletion events occur during development of the somatic macronucleus of the ciliate Tetrahymena. The eliminated Tlr1 element is 13 kb or more in length and has an 825 bp inverted repeat near the rearrangement junctions. A functional analysis of the cis-acting sequences required for Tlr1 rearrangement was performed. A construct consisting of the entire inverted repeat and several hundred base pairs of flanking DNA on each side was rearranged accurately in vivo and displayed junctional variability similar to the chromosomal Tlr1 rearrangement. Thus, 11 kb or more of internal element DNA is not required …

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Substrate Profile In Rat Soleus Muscle Fibers After Hindlimb Unloading And Fatigue, Varvara P. Grichko, Anne R. Heywood-Cooksey, Kameha R. Kidd, Robert H. Fitts Feb 2000

Substrate Profile In Rat Soleus Muscle Fibers After Hindlimb Unloading And Fatigue, Varvara P. Grichko, Anne R. Heywood-Cooksey, Kameha R. Kidd, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Limb muscles from rats flown in space and after hindlimb unloading (HU) show an increased fatigability, and spaceflight has been shown to result in a reduced ability to oxidize fatty acids. The purpose of this investigation was to determine the effects of HU on the substrate content in fast- and slow-twitch fibers and to assess the substrate utilization patterns in single slow type I fibers isolated from control and HU animals.Asecond objective was to assess whether HU altered the ability of the heart or limb muscle to oxidize pyruvate or palmitate. After 2 wk of HU, single fibers were isolated …

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Decreased Thin Filament Density And Length In Human Atrophic Soleus Muscle Fibers After Spaceflight, Danny A. Riley, James L. W. Bain, Joyce L. Thompson, Robert H. Fitts, Jeffrey J. Widrick, Scott W. Trappe, Todd A. Trappe, David L. Costill Feb 2000

Decreased Thin Filament Density And Length In Human Atrophic Soleus Muscle Fibers After Spaceflight, Danny A. Riley, James L. W. Bain, Joyce L. Thompson, Robert H. Fitts, Jeffrey J. Widrick, Scott W. Trappe, Todd A. Trappe, David L. Costill

Biological Sciences Faculty Research and Publications

Soleus muscle fibers were examined electron microscopically from pre- and postflight biopsies of four astronauts orbited for 17 days during the Life and Microgravity Sciences Spacelab Mission (June 1996). Myofilament density and spacing were normalized to a 2.4-μm sarcomere length. Thick filament density (~1,062 filaments/μm2) and spacing (~32.5 nm) were unchanged by spaceflight. Preflight thin filament density (2,976/μm2) decreased significantly (P < 0.01) to 2,215/μm2 in the overlap A band region as a result of a 17% filament loss and a 9% increase in short filaments. Normal fibers had 13% short thin filaments. The 26% decrease in thin filaments …

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Effect Of Spaceflight On The Maximal Shortening Velocity, Morphology, And Enzyme Profile Of Fast- And Slow-Twitch Skeletal Muscle Fibers In Rhesus Monkeys, Robert H. Fitts, Janell Romatowski, Lourdes De La Cruz, Jeffrey J. Widrick, Dominique Desplanches Jan 2000

Effect Of Spaceflight On The Maximal Shortening Velocity, Morphology, And Enzyme Profile Of Fast- And Slow-Twitch Skeletal Muscle Fibers In Rhesus Monkeys, Robert H. Fitts, Janell Romatowski, Lourdes De La Cruz, Jeffrey J. Widrick, Dominique Desplanches

Biological Sciences Faculty Research and Publications

No abstract provided.

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Effect Of Spaceflight On The Isotonic Contractile Properties Of Single Skeletal Muscle Fibers In The Rhesus Monkey, Robert H. Fitts, Janell R. Romatowski, Cynthia A. Blaser, Lourdes J. De La Cruz, Gwen J. Gettelman, Jeffrey J. Widrick Jan 2000

Effect Of Spaceflight On The Isotonic Contractile Properties Of Single Skeletal Muscle Fibers In The Rhesus Monkey, Robert H. Fitts, Janell R. Romatowski, Cynthia A. Blaser, Lourdes J. De La Cruz, Gwen J. Gettelman, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

No abstract provided.

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Segmental Distribution Of Common Synaptic Inputs To Spinal Motoneurons During Fictive Swimming In The Lamprey, James T. Buchanan, Stefan Kasicki Sep 1999

Segmental Distribution Of Common Synaptic Inputs To Spinal Motoneurons During Fictive Swimming In The Lamprey, James T. Buchanan, Stefan Kasicki

Biological Sciences Faculty Research and Publications

These experiments were designed to measure the degree of shared synaptic inputs coming to pairs of myotomal motoneurons during swimming activity in the isolated spinal cord of the lamprey. In addition, the experiments measured the decrease in the degree of shared synaptic inputs with the distance between the motoneurons to assess the segmental distribution of these shared inputs. Intracellular microelectrode recordings of membrane potential were made simultaneously on pairs of myotomal motoneurons during swimming activity induced with an excitatory amino acid. The swim cycle oscillations of motoneuron membrane potentials were removed with a digital notch filter, thus leaving the fast …

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Commissural Interneurons In Rhythm Generation And Intersegmental Coupling In The Lamprey Spinal Cord, James T. Buchanan May 1999

Commissural Interneurons In Rhythm Generation And Intersegmental Coupling In The Lamprey Spinal Cord, James T. Buchanan

Biological Sciences Faculty Research and Publications

Commissural interneurons in rhythm generation and intersegmental coupling in the lamprey spinal cord. To test the necessity of spinal commissural interneurons in the generation of the swim rhythm in lamprey, longitudinal midline cuts of the isolated spinal cord preparation were made. Fictive swimming was then induced by bath perfusion with an excitatory amino acid while recording ventral root activity. When the spinal cord preparation was cut completely along the midline into two lateral hemicords, the rhythmic activity of fictive swimming was lost, usually replaced with continuous ventral root spiking. The loss of the fictive swim rhythm was not due to …

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Effect Of A 17 Day Spaceflight On Contractile Properties Of Human Soleus Muscle Fibres, Jeffrey J. Widrick, Shannon T. Knuth, Kris M. Norenberg, Janell A. Romatowski, James L. W. Bain, Danny A. Riley, M. Karhanek, S. W. Trappe, Todd A. Trappe, David Costill, Robert H. Fitts May 1999

Effect Of A 17 Day Spaceflight On Contractile Properties Of Human Soleus Muscle Fibres, Jeffrey J. Widrick, Shannon T. Knuth, Kris M. Norenberg, Janell A. Romatowski, James L. W. Bain, Danny A. Riley, M. Karhanek, S. W. Trappe, Todd A. Trappe, David Costill, Robert H. Fitts

Biological Sciences Faculty Research and Publications

1. Soleus biopsies were obtained from four male astronauts 45 days before and within 2 h after a 17 day spaceflight. 2. For all astronauts, single chemically skinned post-flight fibres expressing only type I myosin heavy chain (MHC) developed less average peak Ca¥ activated force (Pï) during fixed-end contractions (0·78 ± 0·02 vs. 0·99 ± 0·03 mN) and shortened at a greater mean velocity during unloaded contractions (Vï) (0·83 ± 0·02 vs. 0·64 ± 0·02 fibre lengths s¢) than preflight type I fibres. 3. The flight-induced decline in absolute Pï was attributed to reductions in fibre diameter and Ï or …

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Physiological And Morphological Correlates Of Presynaptic Inhibition In Primary Afferents Of The Lamprey Spinal Cord, I. V. Batueva, E. A. Tsvetkov, A. K. Sagatelyan, James T. Buchanan, N. Vesselkin, V. Adanina, E. I. Suderevskaya, J. -P Rio, J. Repérant Feb 1999

Physiological And Morphological Correlates Of Presynaptic Inhibition In Primary Afferents Of The Lamprey Spinal Cord, I. V. Batueva, E. A. Tsvetkov, A. K. Sagatelyan, James T. Buchanan, N. Vesselkin, V. Adanina, E. I. Suderevskaya, J. -P Rio, J. Repérant

Biological Sciences Faculty Research and Publications

Patch-clamp recordings in a whole-cell mode were performed on dorsal sensory cells enzymatically isolated from the spinal cord of two lamprey species, Ichthyomyzon unicuspis and Lampetra fluviatilis. The voltage-activated currents through calcium channels were analysed. GABA and the specific GABAB receptor agonist baclofen reduced the peak amplitude of inward Ba2+ current, as a robust alternate charge carrier through voltage-dependent Ca2+ channels. These effects were dose-dependent and reversible. GABAB receptor antagonists, 2-hydroxysaclofen and δ-amino-n-valeric acid, blocked the reduction of Ba2+ currents by GABA and baclofen, while bicuculline, a GABAA receptor antagonist, had no blocking …

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Developmental Changes In The Nicotinic Responses Of Ciliary Ganglion Neurons, Edward M. Blumenthal, Richard D. Shoop, Darwin K. Berg Jan 1999

Developmental Changes In The Nicotinic Responses Of Ciliary Ganglion Neurons, Edward M. Blumenthal, Richard D. Shoop, Darwin K. Berg

Biological Sciences Faculty Research and Publications

Developmental changes in the nicotinic responses of ciliary ganglion neurons. J. Neurophysiol. 81: 111–120, 1999. The accumulation of functional neurotransmitter receptors by neurons during development is an essential part of synapse formation. Chick ciliary ganglion neurons express two kinds of nicotinic receptors. One is abundant, contains the α7 gene product, rapidly desensitizes, and binds α-bungarotoxin. The other is less abundant, contains multiple gene products (α3, β4, α5, and β2 subunits), slowly desensitizes, and binds the monoclonal antibody mAb 35. Rapid application of agonist to freshly dissociated neurons elicits responses from both classes of receptors. Between embryonic days 8 and 15, …

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Five Myofibrillar Lesion Types In Eccentrically Challenged, Unloaded Rat Adductor Longus Muscle—A Test Model, Joyce L. Thompson, Edward Michael Balog, Robert H. Fitts, Danny A. Riley Jan 1999

Five Myofibrillar Lesion Types In Eccentrically Challenged, Unloaded Rat Adductor Longus Muscle—A Test Model, Joyce L. Thompson, Edward Michael Balog, Robert H. Fitts, Danny A. Riley

Biological Sciences Faculty Research and Publications

Sarcomere disruptions are observed in the adductor longus (AL) muscles following voluntary reloading of spaceflown and hindlimb suspension unloaded (HSU) rat, which resemble lesions in eccentrically challenged muscle. We devised and tested an eccentric contraction (ECCON) test system for the 14-day HSU rat AL. Six to 7 hours following ECCON, ALs were fixed to allow immunostaining and electron microscopy (EM). Toluidine blue-stained histology semithin sections were screened for lesion density (#/mm2). Serial semithin sections from the ECCON group were characterized for myosin immunointensity of lesions. Five myofibrillar lesion types were identified in histological semithin sections: focal contractions; wide …

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Substrate And Enzyme Profile Of Fast And Slow Skeletal Muscle Fibers In Rhesus Monkeys, Varvara P. Grichko, Gwen J. Gettelman, Jeffrey Widrick, Robert H. Fitts Jan 1999

Substrate And Enzyme Profile Of Fast And Slow Skeletal Muscle Fibers In Rhesus Monkeys, Varvara P. Grichko, Gwen J. Gettelman, Jeffrey Widrick, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Results from the Russian Cosmos program suggest that the rhesus monkey is an excellent model for studying weightlessness-induced changes in muscle function. Consequently, the purpose of this investigation was to establish the resting levels of selected substrate and enzymes in individual slow- and fast-twitch muscle fibers of the rhesus monkey. A second objective was to determine the effect of an 18-day sit in the Spacelab experiment-support primate facility [Experimental System for the Orbiting Primate (ESOP)]. Muscle biopsies of the soleus and medial gastrocnemius muscles were obtained 1 mo before and immediately after an 18-day ESOP sit. The biopsies were freeze-dried, …

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Force-Velocity-Power And Force-Pca Relationships Of Human Soleus Fibers After 17 Days Of Bed Rest, Jeffrey J. Widrick, Kris M. Norenberg, C. A. Blaser, M. Karhanek, Jennifer J. Sherwood, Scott W. Trappe, Todd A. Trappe, David L. Costill, Robert H. Fitts Nov 1998

Force-Velocity-Power And Force-Pca Relationships Of Human Soleus Fibers After 17 Days Of Bed Rest, Jeffrey J. Widrick, Kris M. Norenberg, C. A. Blaser, M. Karhanek, Jennifer J. Sherwood, Scott W. Trappe, Todd A. Trappe, David L. Costill, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Soleus muscle fibers from the rat display a reduction in peak power and Ca2+ sensitivity after hindlimb suspension. To examine human responses to non-weight bearing, we obtained soleus biopsies from eight adult men before and immediately after 17 days of bed rest (BR). Single chemically skinned fibers were mounted between a force transducer and a servo-controlled position motor and activated with maximal (isotonic properties) and/or submaximal (Ca2+ sensitivity) levels of free Ca2+. Gel electrophoresis indicated that all pre- and post-BR fibers expressed type I myosin heavy chain. Post-BR fibers obtained from one subject displayed increases in …

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Position Effect Takes Precedence Over Target Sequence In Determination Of Adenine Methylation Patterns In The Nuclear Genome Of A Eukaryote, Tetrahymena Thermophila, Kathleen M. Karrer, Teresa A. Van Nuland Oct 1998

Position Effect Takes Precedence Over Target Sequence In Determination Of Adenine Methylation Patterns In The Nuclear Genome Of A Eukaryote, Tetrahymena Thermophila, Kathleen M. Karrer, Teresa A. Van Nuland

Biological Sciences Faculty Research and Publications

Approximately 0.8% of the adenine residues in the macronuclear DNA of the ciliated protozoan Tetrahymena thermophila are modified to N6-methyladenine. DNA methylation is site specific and the pattern of methylation is constant between clonal cell lines. In vivo, modification of adenine residues appears to occur exclusively in the sequence 5′-NAT-3′, but no consensus sequence for modified sites has been found. In this study, DNA fragments containing a site that is uniformly methylated on the 50 copies of the macronuclear chromosome were cloned into the extrachromosomal rDNA. In the novel location on the rDNA minichromosome, the site was …

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Concerted Formation Of Macromolecular Suppressor-Mutator Transposition Complexes, Ramesh Raina, Michael Schläppi, Balasulojini Karunanandaa, Adam Elhofy, Nina V. Fedoroff Jul 1998

Concerted Formation Of Macromolecular Suppressor-Mutator Transposition Complexes, Ramesh Raina, Michael Schläppi, Balasulojini Karunanandaa, Adam Elhofy, Nina V. Fedoroff

Biological Sciences Faculty Research and Publications

Transposition of the maize Suppressor-mutator (Spm) transposon requires two element-encoded proteins, TnpA and TnpD. Although there are multiple TnpA binding sites near each element end, binding of TnpA to DNA is not cooperative, and the binding affinity is not markedly affected by the number of binding sites per DNA fragment. However, intermolecular complexes form cooperatively between DNA fragments with three or more TnpA binding sites. TnpD, itself not a sequence-specific DNA-binding protein, binds to TnpA and stabilizes the TnpA-DNA complex. The high redundancy of TnpA binding sites at both element ends and the protein-protein interactions between DNA-bound TnpA …

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Velocity, Force, Power, And Ca2+ Sensitivity Of Fast And Slow Monkey Skeletal Muscle Fibers, Robert Fitts, Sue C. Bodine, Janell Romatowski, Jeffrey J. Widrick May 1998

Velocity, Force, Power, And Ca2+ Sensitivity Of Fast And Slow Monkey Skeletal Muscle Fibers, Robert Fitts, Sue C. Bodine, Janell Romatowski, Jeffrey J. Widrick

Biological Sciences Faculty Research and Publications

In this study, we determined the contractile properties of single chemically skinned fibers prepared from the medial gastrocnemius (MG) and soleus (Sol) muscles of adult male rhesus monkeys and assessed the effects of the spaceflight living facility known as the experiment support primate facility (ESOP). Muscle biopsies were obtained 4 wk before and immediately after an 18-day ESOP sit, and fiber type was determined by immunohistochemical techniques. The MG slow type I fiber was significantly smaller than the MG type II, Sol type I, and Sol type II fibers. The ESOP sit caused a significant reduction in the diameter of …

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