Physiology Commons^™

Aminoacyl-Trnas: Setting The Limits Of The Genetic Code, Michael Ibba, Dieter Söll

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Aminoacyl-tRNAs (aa-tRNAs) are simple molecules with a single purpose—to serve as substrates for translation. They consist of mature tRNAs to which an amino acid has been esterified at the 3′-end. The 20 different types of aa-tRNA are made by the 20 different aminoacyl-tRNA synthetases (aaRSs, of which there are two classes), one for each amino acid of the genetic code (Ibba and Söll 2000). This would be fine if it were not for the fact that such a straightforward textbook scenario is not true in a single known living organism. aa-tRNAs lie at the heart of gene expression; they interpret …

Intravenous 2-Deoxy-D-Glucose Injection Rapidly Elevates Levels Of The Phosphorylated Forms Of P44/42 Mitogen-Activated Protein Kinases (Extracellularly Regulated Kinases 1/2) In Rat Hypothalamic Parvicellular Paraventricular Neurons, Arshad Khan, Alan G. Watts

Arshad M. Khan, Ph.D.

No abstract provided.

Prediction Of Fetal Sheep Brain Metabolic Rate During Hypoxia And Cord Occlusion, Adam D. Hickerson

Loma Linda University Electronic Theses, Dissertations & Projects

Many investigators have observed that fetal and neonatal animals are remarkably tolerant to hypoxia compared to the adult. The precise mechanisms however are still unclear. In order to better characterize the hemodynamic and metabolic responses of the fetal brain to hypoxic stress, we have designed a mathematical model to predict tissue oxygenation and metabolic rate of the fetal brain during both moderate hypoxia and severe asphyxia.

The model is based on the Krogh cylinder concept and is similar to one previously published by our lab. Several new concepts were added including the ability to run the model over time using …

Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor

Dartmouth Scholarship

Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living alpha-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established a transient …

Regulation Of Connexin43 By Phosphorylation, Maithili M. Shah

Loma Linda University Electronic Theses, Dissertations & Projects

Gap junctions play a crucial role in embryogenesis, especially of the heart where connexin43 is thought to be important for its formation as well as synchronized contraction. Several reports have shown that connexin43 protein is phosphorylated on serine residues in vitro and in vivo.

Studies performed in our laboratory have demonstrated that cell-to-cell communication in cells expressing connexin43 can be controlled rapidly and reversibly by microinjection of active protein kinases or phosphatases that target serine or threonine residues. Phosphorylation by cAMP-dependent protein kinase (PKA) seems to favor channel opening, whereas the effect of protein kinase C (PKC) on channel gating …

Atherosclerosis And Plaque Rupture: An Update, M N. Afzal, S A. Saeed, B H. Shah

Department of Biological & Biomedical Sciences

No abstract provided.

Archaeal Aminoacyl-Trna Synthesis: Unique Determinants Of A Universal Genetic Code?, Michael Ibba, A. W. Curnow, J. Bono, P. A. Rosa, C. R. Woese, D. Söll

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

No abstract provided.

Lateral Hypothalamic Nmda Receptor Subunits Nr2a And/Or Nr2b Mediate Eating: Immunochemical/Behavioral Evidence, Arshad Khan, Margarita C. Curras, Jennifer Dao, Faizi A. Jamal, Rishi K. Goel, Elizabeth R. Gillard, Stefany D. Wolfsohn, B. Glenn Stanley

Arshad M. Khan, Ph.D.

No abstract provided.

Characterization Of The Biological Functions Of Human Recombinant Zona Pellucida Protein 3, Yu Wen Juan

Theses and Dissertations in Biomedical Sciences

Recombinant human zona pellucida protein 3 (rhZP3), expressed. isolated and purified from PA-1 cells, is characterized for its biological activity and the role in the signal transduction pathway. Characterization of the biological activity of rhZP3 was detected by hemizona assay and immunofluorescence staining of acrosome reaction The results indicated that rhZP3 exhibited an inhibition in the binding assay (HZI 43.6 +/-3.3; n = 9; 30 ng/mL rhZP3) and induction of acrosome reaction (198.6% +/- 77.2% increase from baseline; n = 29; 30 ng/mL rhZP3). It was further confirmed by the transmission electron microscopy that there was no difference in morphology …

The Second Messenger Camp Elicits Eating By An Anatomically Specific Action In The Perifornical Hypothalamus, Elizabeth R. Gillard, Arshad M. Khan, Rickinder S. Grewal, Bara Mouradi, Stefany D. Wolfsohn, B. Glenn Stanley

Arshad M. Khan, Ph.D.

No abstract provided.

Eating Induced By Perifornical Camp Is Behaviorally Selective And Involves Protein Kinase Activity, Elizabeth R. Gillard, Arshad M. Khan, Bara Mouradi, Omkar Nalamwar, B. Glenn Stanley

Arshad M. Khan, Ph.D.

No abstract provided.

Choline Acetyltransferase And Carnitine Acetyltransferase Activity In Human Spermatozoa During Capacitation, Lisa A. Eccles

Theses and Dissertations in Biomedical Sciences

The regional distribution of ChAT activity in human spermatozoa is altered during in vitro capacitation and it correlates with the fertilizing potential of sperm.

Regional immunoreactivity in human spermatozoa as assessed by fluorescent immunocytochemistry was compared with ChAT and CaAT activity determined by enzymatic methodologies. Increasing proportions of sperm exhibited ChAT immunoreactivity along the equatorial region with a concomitant decrease in ChAT reactivity in the midpiece. Also, competitive studies with unlabeled ChAT blocked the equatorial region labeling; the unlabeled CaAT blocked staining along the midpiece region of the tail, suggesting some cross-reactivity of the ChAT antiserum with the CaAT enzyme. …

Circadian Clock-Controlled Genes Isolated From Neurospora Crassa Are Late Night- To Early Morning-Specific, Deborah Bell-Pedersen, Mari L. Shinohara, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

An endogenous circadian biological clock controls the temporal aspects of life in most organisms, including rhythmic control of genes involved in clock output pathways. In the fungus Neurospora crassa, one pathway known to be under control of the clock is asexual spore (conidia) development. To understand more fully the processes that are regulated by the N. crassa circadian clock, systematic screens were carried out for genes that oscillate at the transcriptional level. Time-of-day-specific cDNA libraries were generated and used in differential screens to identify six new clock-controlled genes (ccgs). Transcripts specific for each of the ccgs …

A Kinetic Investigation Of The Mechanism Of Muscle Contraction With A Series Of Nucleotides, Wei Jiang

Theses and Dissertations in Biomedical Sciences

Muscle contraction is thought to be accomplished by sliding of myosin filaments along actin filaments. Although actomyosin naturally uses ATP as an energy source, it can also use other nucleoside triphosphates (NTP) as substrates. In this work, the dependence of rate and equilibrium constants of the various steps in the muscle contraction mechanism upon nucleotide structure was investigated to unravel the dependence of the mechanical properties of the muscle upon changes in different biochemical steps of the mechanism.

The experiments measuring the dissociation of actomyosin by NTP (or mant-NTP) shows that both the rate constant of actomyosin-S1 dissociation and second …

Circadian Clock Locus Frequency: Protein Encoded By A Single Open Reading Frame Defines Period Length And Temperature Compensation., Benjamin D. Aronson, Keith A. Johnson, Jay C. Dunlap

Dartmouth Scholarship

The frequency (frq) locus encodes a key component, a state variable, in a cellular oscillator generating circadian rhythmicity. Two transcripts have been mapped to this region, and data presented here are consistent with the existence of a third transcript. Analysis of cDNA clones and clock mutants from this region focuses attention on one transcript encoding a protein. FRQ, which is a central clock component: (i) mutations in all of the semidominant frq alleles are the result of single amino acid substitutions and map to the open reading frame (ORF) encoding FRQ; (ii) deletion of this ORF, or a frameshift mutation …

Uptake Routes Of Benzo[A]Pyrene In An Estuarine Killifish: Cytochrome P4501a Immunohistochemistry Using Whole Fish, Maria Karin Cochran

Dissertations, Theses, and Masters Projects

No abstract provided.

Myocardial Alpha-Thrombin Receptor Activation Induces Hypertrophy And Increases Atrial Natriuretic Factor Gene Expression, C C. Glembotski, C E. Irons, K A. Krown, S F. Murray, A B. Sprenkle, C A. Sei

Amy Sprenkle

The Alpha-Adrenergic Stimulation Of Atrial Natriuretic Factor Expression In Cardiac Myocytes Requires Calcium Influx, Protein Kinase C, And Calmodulin-Regulated Pathways, C A. Sei, C E. Irons, A B. Sprenkle, P M. Mcdonough, J H. Brown, C C. Glembotski

Amy Sprenkle

Spectroscopic Study Of Decomposition Products Of Gossypol, David Bernard Hankins

Chemistry & Biochemistry Theses & Dissertations

Basic research into reproductive physiology has begun to identify possible new approaches to controlling fertility. Gossypol, a natural polyphenol compound isolated from cottonseed oil, has been shown to be an effective male antifertility agent. The decomposition products of gossypol which are thought to possess more potent antifertility effects than the parent compound gossypol have been studied extensively in more recent research. The purpose of this research is to develop techniques and methods which could be used to identify decomposition products of gossypol. A model decomposition reaction by which a smaller molecule can be isolated in a pure state has been …

Regulation Of Epidermal Growth Factor Receptor Synthesis By Retinoic Acid And Dexamethasone, Kerby C. Oberg

Loma Linda University Electronic Theses, Dissertations & Projects

Fetal rat lung (FRL) cells incubated in the presence of retinoic acid or dexamethasone exhibit altered ¹²⁵I-epidermal growth factor (EOF) binding capacity. Retinoic acid enhances ¹²⁵I-EGF binding 3-fold following 24 hours of 37° incubation. In contrast, FRL cells incubated in the presence of dexamethasone display a 2-fold reduction in ¹²⁵I-EGF binding capacity. The change in binding capacity, induced by either hormone, was due to alterations in the average number of receptors per cell as determined by Scatchard analysis of ¹²⁵I-EGF binding. In the absence of retinoic acid or dexamethasone, FRL cells were calculated to have approximately …

The Physiology And Biochemistry Of Isolated Skeletal Muscle Mitochondria : A Comparative Study, Mark Lowell Wagner

Dissertations and Theses

The physiological limit to maximum aerobic capacity (VO₂max) in vertebrates has been attributed to cardiovascular oxygen delivery, to the ability of the muscle cells to consume oxygen, or to a fine-tuned development of all components of the respiratory system such that no single component can be shown to limit VO₂max. The above hypotheses have each been developed using different experiments with different animals. The comparative studies uniting these animals and methods are limited. In order to further our knowledge of the cellular limit to VO₂max, skeletal muscle mitochondria were isolated from species representing four …

An Analysis Of Protein-Ligand Interactions For Enzyme Ii-Mannitol From Escherichia Coli, Brent Lee Wood

Loma Linda University Electronic Theses, Dissertations & Projects

Enzyme II^mtl of Escherichia coli was purified from mtlA-overexpressing E. coli strain LJ1112 extraction of isolated membranes with deoxycholate, followed by hexyl agarose and ω-amino hexyl agarose chromatography in Lubrol PX. A 10-fold increase in total pure protein and 2.5-fold increase in specific activity over previously reported procedures was obtained. Tryptic fragments of Enzyme II^mtl were also purified and identified as the membrane and cytoplasmic domains by protein sequencing and SDS-PAGE. The fluorescence spectrum of Enzyme II^mtl suggested that two populations of tryptophan residues existed with emission maxima at 322 and 344 nm, corresponding to buried …

Signal Processing In Bacterial Chemotaxis, Jimmie Marquette Smith

Loma Linda University Electronic Theses, Dissertations & Projects

This study localized 1) the site of ATP utilization in the signal transduction pathway of bacterial chemotaxis and 2) the point of convergence of the methylation-independent systems of chemotaxis with the methylation-dependent system. The site of ATP utilization was localized at the CheY protein/switch point. In an Eaeheriehia call strain (BT3077) containing the cheY, motor and switch genes, ATP depletion, accomplished by treating the cells with arsenate, suppressed the CheY protein-induced tumbling. ATP was not required by the switch for directing the clockwise and counterclockwise rotations of the flagellar motor. ATP did not appear to be required for normal steady-state …

Quantitation And Identification Of Organic N-Chloramines Formed In Stomach Fluid On Ingestion Of Aqueous Hypochlorite, Frank E. Scully Jr., Katherine Mazina, Daniel E. Sonenshine, Frederick Kopfler

Biological Sciences Faculty Publications

The chemical reactions that hypochlorite undergoes in the body when chlorinated water is ingested have received very little attention. Because amino nitrogen compounds are important components of the average diet, the reactions of hypochlorite with amino compounds in the stomach were investigated. Stomach fluid was recovered from Sprague-Dawley rats that had been fasted for 48 hr and administered 4 mL deionized water. The chlorine demand of the stomach fluid was determined. An average volume-independent demand of 2.7 mg chlorine was measured. At doses below 40 mg/L chlorine reducing reactions appeared to account for reduction of all oxidizing species within 15 …

Pathological Physiology As A Basis For Medical Practice, Walter E. Macpherson

Medical Arts and Sciences: A Scientific Journal of the College of Medical Evangelists

No abstract provided.