Physiology Commons^™

A Subset Of Arabidopsis Ap2 Transcription Factors Mediates Cytokinin Responses In Concert With A Two-Component Pathway, Aaron M. Rashotte, Michael G. Mason, Claire E. Hutchison, Fernando J. Ferreira, G. Eric Schaller, Joseph J. Kieber

Dartmouth Scholarship

The plant hormone cytokinin regulates numerous growth and developmental processes. A signal transduction pathway for cytokinin has been elucidated that is similar to bacterial two-component phosphorelays. In Arabidopsis, this pathway is comprised of receptors that are similar to sensor histidine kinases, histidine-containing phosphotransfer proteins, and response regulators (ARRs). There are two classes of response regulators, the type-A ARRs, which act as negative regulators of cytokinin responses, and the type-B ARRs, which are transcription factors that play a positive role in mediating cytokinin-regulated gene expression. Here we show that several closely related members of the Arabidopsis AP2 gene family of …

Molecular Analysis Of The Effects Of Atrazine On Xenopus Laevis Frogs, Ronald Edward Celestine

Dissertations

Atrazine, the most commonly used herbicide in the U.S., has been implicated as one of the factors that may be causing the worldwide decline of amphibians. First, I examined effects of atrazine on laboratory raised Xenopus laevis tadpoles, treated from 5 days post fertilization to NF stage 65/66 with a concentrationof 25 ppb of atrazine. This study showed no significant difference in body weight, length and metamorphic rate.

Second, I used DNA microarrays to examine mRNA expression levels of genes in atrazine treated and control Xenopus laevis tadpoles. I found significant changes in gene expression levels of 18 genes. These …

Time Constraints Mediate Predator-Induced Plasticity In Immune Function, Condition, And Life History, Robby Stoks, Marjan De Block, Stefanie Slos, Wendy Van Doorslaer, Jens Rolff

Dartmouth Scholarship

The simultaneous presence of predators and a limited time for development imposes a conflict: accelerating growth under time constraints comes at the cost of higher predation risk mediated by increased foraging. The few studies that have addressed this trade-off have dealt only with life history traits such as age and size at maturity. Physiological traits have largely been ignored in studies assessing the impact of environmental stressors, and it is largely unknown whether they respond independently of life history traits. Here, we studied the simultaneous effects of time constraints, i.e., as imposed by seasonality, and predation risk on immune defense, …

Physiological Effects On Demography: A Long‐Term Experimental Study Of Testosterone’S Effects On Fitness, W. Reed, M. Clark, P. Parker, S. Raouf, N. Arguedas, D. Monk, E. Snajdr, V. Nolan, E. Ketterson

Biology Department Faculty Works

Understanding physiological and behavioral mechanisms underlying the diversity of observed life‐history strategies is challenging because of difficulties in obtaining long‐term measures of fitness and in relating fitness to these mechanisms. We evaluated effects of experimentally elevated testosterone on male fitness in a population of dark‐eyed juncos studied over nine breeding seasons using a demographic modeling approach. Elevated levels of testosterone decreased survival rates but increased success of producing extra‐pair offspring. Higher overall fitness for testosterone‐treated males was unexpected and led us to consider indirect effects of testosterone on offspring and females. Nest success was similar for testosterone‐treated and control males, …

Allostasis, Homeostasis, And The Costs Of Physiological Adaptation, Sarah C. Coste

Faculty Publications

Sarah Coste reviews Allostasis, Homeostasis, and the Costs of Physiological Adaptation (edited by Jay Schulkin) for the Quarterly Review of Biology.

The Relationship Between Frq-Protein Stability And Temperature Compensation In The Neurospora Circadian Clock, Peter Ruoff, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Temperature compensation is an important property of all biological clocks. In Neurospora crassa, negative-feedback regulation on the frequency (frq) gene's transcription by the FRQ protein plays a central role in the organism's circadian pacemaker. Earlier model calculations predicted that the stability of FRQ should determine the period length of Neurospora's circadian rhythm as well as the rhythm's temperature compensation. Here, we report experimental FRQ protein stabilities in frq mutants at 20 degrees C and 25 degrees C, and estimates of overall activation energies for mutant FRQ protein degradation. The results are consistent with earlier model predictions, i.e., temperature compensation of …

Response Of Stress Levels In Domestic Canines To Calming Pheromone, Kathleen Barrett

Honors Capstones

Capstone submitted as a graduation requirement for the BSU Honors Program.

Immune-Endocrine Interactions In The Lizard Sceloporus Undulatus Hyacinthinus: Testing An Assumption Of The Immunocompetence Handicap Hypothesis, Mukta Chakraborty

All-Inclusive List of Electronic Theses and Dissertations

The immunocompetence handicap hypothesis (IHH) was proposed by Folstad and Karter ( 1992) to describe the role of the endocrine system in ensuring honesty of sexual signaling. Numerous studies have investigated the assumptions of the IHH, but currently there is mixed evidential support in favor of the IHH. The first chapter of this thesis is a review examinining these studies, their limitations, and proposed alternative models and future directions. The second chapter of this thesis presents a study in which we experimentally assesss the testosterone immunosuppression assumption in adult male Sceloporus undulatus lizards. We manipulated circulating androgen levels (Day 0) …

From The Cover: Assignment Of An Essential Role For The Neurospora Frequency Gene In Circadian Entrainment To Temperature Cycles, Antonio M. Pregueiro, Nathan Price-Lloyd, Deborah Bell-Pedersen, Christian Heintzen, Jennifer J. Loros, Jay C. Dunlap

Dartmouth Scholarship

Circadian systems include slave oscillators and central pacemakers, and the cores of eukaryotic circadian clocks described to date are composed of transcription and translation feedback loops (TTFLs). In the model system Neurospora, normal circadian rhythmicity requires a TTFL in which a White Collar complex (WCC) activates expression of the frequency (frq) gene, and the FRQ protein feeds back to attenuate that activation. To further test the centrality of this TTFL to the circadian mechanism in Neurospora, we used low-amplitude temperature cycles to compare WT and frq-null strains under conditions in which a banding rhythm was elicited. WT cultures were entrained …

Preservation Of Eumelanin Hair Pigmentation In Proopiomelanocortin-Deficient Mice On A Nonagouti (A/A) Genetic Background, Andrzej Slominski, Przemyslaw M. Plonka, Alexander Pisarchik, James L. Smart, Virgine Tolle, Jacobo Wortsman, Malcolm J. Low

Faculty Publications - Department of Biological & Molecular Science

No abstract provided.

3,4-Methylenedioxymethamphetamine Activates Nuclear Factor- Κb, Increases Intracellular Calcium, And Modulates Gene Transcription In Rat Heart Cells, David A. Tiangco, Frank A. Lattanzio Jr., Christopher J. Osgood, Stephen J. Beebe, Julie A. Kerry, Barbara Y. Hargrave

Biological Sciences Faculty Publications

3,4-Methylenedioxymethamphetamine (MDMA) is an illicit psychoactive drug that has gained immense popularity among teenagers and young adults. The cardiovascular toxicological consequences of abusing this compound have not been fully characterized. The present study utilized a transient transfection/dual luciferase genetic reporter assay, fluorescence confocal microscopy, and gene expression macroarray technology to determine nuclear factor-κB (NF-κB) activity, intracellular calcium balance, mitochondrial depolarization, and gene transcription profiles, respectively, in cultured rat striated cardiac myocytes (H9c2) exposed to MDMA. At concentrations of 1×10⁻³ M and 1×10⁻² M, MDMA significantly enhanced NF-κB reporter activity compared with 0 M (medium only) control. This …

Size And Organic Content Of Eggs Of Marine Annelids, And The Underestimation Of Egg Energy Content By Dichromate Oxidation, William Jaeckle, Bruno Pernet

Scholarship

Dichromate oxidation is a simple technique that is often used to estimate the energy content of eggs in studies of marine invertebrate life histories (1). We used this method to measure the energy contents of the eggs of 12 species of marine annelids. In combination with measures of egg ash-free dry weight (AFDW), these data yielded estimates of AFDW-specific energy density that were mostly lower than the average weight-specific energy density of carbohydrates. This seemed unlikely to be correct, as invertebrate eggs typically contain little carbohydrate and instead are composed primarily of energy-dense protein and lipid (1, 2). After validating …

Changes In Gdnf Protein Content Of Skeletal Muscle Following Involuntary Exercise Are Long Lived, Kyle R. Kinnell, Monica J. Czarnopys, John Spitsbergen

Biological Sciences Faculty and Graduate Student Research

Glial-cell line derived neurotrophic factor (GDNF) is a neurotrophic factor produced by skeletal muscle. GDNF has been shown to be potent survival factor for motor neurons. We have previously shown that GDNF content in skeletal muscle is altered following exercise and GDNF levels 24 hours after the last bout of exercise are significantly different than those measured immediately after exercise. We sought to determine how long after exercise do GDNF protein levels remain altered. We removed extensor digitorum longus (EDL) and Soleus (SOL), 24 hr, 72 hr and 1 week following the last bout of involuntary exercise. Muscles were processed …

Hatching Asynchrony, Survival, And The Fitness Of Alternative Adult Morphs In Ambystoma Talpoideum, Travis J. Ryan

Scholarship and Professional Work - LAS

The mole salamander, Ambystoma talpoideum, exhibits both aquatic (gilled) and terrestrial (metamorphosed) adult morphologies. Previous studies have shown the existence of body-size advantages associated with the terrestrial morph in A. talpoideum and other polymorphic salamanders (e.g., A. tigrinum). However, aquatic adult A. talpoideum mature at a younger age and often breed earlier than terrestrial adults. We tested the hypothesis that early maturation and reproduction in aquatic adults increase fitness (irrespective of body size). We reared larval A. talpoideum in mesocosms and varied the timing of hatching, with early-hatching larvae representing the offspring from early-breeding aquatic adults, and late-hatching larvae representing …

Variability In Broods Of The Seastar Leptasterias Aequalis, William B. Jaeckle, Brian L. Bingham, Kehualani Giles

Scholarship

Enormous variation exists in the reproductive output of marine invertebrates (e.g., in the numbers of em¬bryos produced, the volumes of embryos, and the energy that they contain). It is not clear why there is such great variability or what the population-level consequences are. We sampled a population of the brooding seastar Leptasterias aequalis (Stimpson, 1862) to collect basic information on brood sizes, embryo volume, and embryo energy content with a goal to better understand the reproductive ecology of this species. We collected brooding females in February and again in April. We measured the size of their broods and sampled the …

Thermoregulation In Swimming Mallard Ducklings (Anas Platyrhynchos), Aaron James Lynott

All-Inclusive List of Electronic Theses and Dissertations

Temperature regulation in birds has been studied for several decades. However, most studies have been limited to the thermal effects of air. This is surprising considering the abundance of waterfowl and the significant amount of time that many birds spend immersed in water. While we do know that water has a thermal conductivity that is 23 times that of air, the effect of water temperature on temperature regulation remains unknown. Though the thermal effect of water seemingly has a strong influence on the thermoregulation of birds, neonatal aquatic birds seem particularly susceptible. Many aquatic neonates, such as mallard ducklings, enter …

Two Arabidopsis Circadian Oscillators Can Be Distinguished By Differential Temperature Sensitivity, Todd P. Michael, Patrice A. Salome, C. Robertson Mcclung

Dartmouth Scholarship

Circadian rhythms are widespread in nature and reflect the activity of an endogenous biological clock. In metazoans, the circadian system includes a central circadian clock in the brain as well as distinct clocks in peripheral tissues such as the retina or liver. Similarly, plants have distinct clocks in different cell layers and tissues. Here, we show that two different circadian clocks, distinguishable by their sensitivity to environmental temperature signals, regulate the transcription of genes that are expressed in the Arabidopsis thaliana cotyledon. One oscillator, which regulates CAB2 expression, responds preferentially to light–dark versus temperature cycles and fails to respond to …

Temperature Regulation And The Constraints Of Climate In The Eared Grebe, Hugh I. Ellis, Joseph R. Jehl Jr

Biology: Faculty Scholarship

Eared Grebes (Podiceps nigricollis) encounter a variety of climatic regimes in their annual cycle. The most dramatic occur while on staging areas in autumn. We investigated the thermoregulatory abilities of the Eared Grebe to determine how they coped with these climate changes during staging. The basal metabolic rate (BMR) was higher than predicted. Mass-specific BMR was 1.212 mL O2/g·h for birds averaging 317 g. The thermoneutral zone is wide and extended from 15°C to 38°C. Minimal thermal conductance and average body temperature were not unusual. We conclude that Eared Grebes live most of the year under thermoneutral conditions and that …

Asymmetry Of The Central Apparatus Defines The Location Of Active Microtubule Sliding In Chlamydomonas Flagella, Matthew J. Wargo, Elizabeth F. Smith

Dartmouth Scholarship

Regulation of ciliary and flagellar motility requires spatial control of dynein-driven microtubule sliding. However, the mechanism for regulating the location and symmetry of dynein activity is not understood. One hypothesis is that the asymmetrically organized central apparatus, through interactions with the radial spokes, transmits a signal to regulate dynein-driven microtubule sliding between subsets of doublet microtubules. Based on this model, we hypothesized that the orientation of the central apparatus defines positions of active microtubule sliding required to control bending in the axoneme. To test this, we induced microtubule sliding in axonemes isolated from wild-type and mutant Chlamydomonas cells, and then …

Exposure Of Nervous System Cells To Polychlorinated Biphenyls (Pcbs) Results In Significant Alterations In Levels Of Expression Of Neurotrophic Factors, Charles F. Ide, Jay C. Means, Trisha M. Basford, John Spitsbergen

Biological Sciences Faculty and Graduate Student Research

Toxic insult by PCBs results in learning and memory deficits in humans. Alterations in expression of neurotrophic factors and/or their receptors have been linked to changes in cognition. How PCBs affect cognition is not known. We propose that PCBs affect cognition by altering neurotrophic factor expression or effects. We exposed cultured C6 glial cells in medium containing PCB (Aroclor 1254 (10ppm)). Control cells were treated with DMSO or regular medium. Cells were incubated at 37o C for up to 72 hours. Medium samples were taken at 6hr, 24hr, 48hr, and 72hr intervals. Enzyme-linked immunosorbent assays (ELISA) were used to determine …

Hypothalamic Proopiomelanocortin Neurons Are Glucose Responsive And Express Katp Channels, Nurhadi Ibrahim, Martha A. Bosch, James L. Smart, Jian Qiu, Marcelo Rubinstein, Oline K. Rønnekleiv, Malcolm J. Low, Martin J. Kelly

Faculty Publications - Department of Biological & Molecular Science

Hypothalamic proopiomelanocortin (POMC) neurons are critical for controlling homeostatic functions in the mammal. We used a transgenic mouse model in which the POMC neurons were labeled with enhanced green fluorescent protein to perform visualized, whole-cell patch recordings from prepubertal female hypothalamic slices. The mouse POMC-enhanced green fluorescent protein neurons expressed the same endogenous conductances (a transient outward K current and a hyperpolarization-activated, cation current) that have been described for guinea pig POMC neurons. In addition, the selective -opioid receptor agonist DAMGO induced an outward current (maximum of 12.8 1.2 pA), which reversed at K equilibrium potential (EK), in the majority …

The Anorexigenic Fatty Acid Synthase Inhibitor, C75, Is A Nonspecific Neuronal Activator, Kanji A. Takahashi, James L. Smart, Hongyan Liu, Roger D. Cone

Faculty Publications - Department of Biological & Molecular Science

C75, a recently derived compound that potently suppresses feeding and induces weight loss, has been proposed to act mainly by inhibiting fatty acid synthase (FAS) in central neurons that control feeding. For example, normal, fasting- associated, hypothalamic increases in neuropeptide Y (NPY)/Agouti-related protein (AGRP) expression and decreases in proopiomelanocortin (POMC)/cocaine and amphetamine regulated transcript (CART) expression were reported to be blocked by C75. Using loose-patch extracellular recording in acute slices, we tested the effect of C75 on anorexigenic POMC neurons and orexigenic NPY neurons of the hypothalamic arcuate nucleus, which were identified by promoter-driven GFP expression, as well as on …

Identification Of Asteroid Genera With Species Capable Of Larval Cloning, K. E. Knott, E. J. Balser, William Jaeckle

Scholarship

Asexual reproduction in larvae, larval cloning, is a recently recognized component of the complex life histories of asteroids. We compare DNA sequences of mitochondrial tRNA genes (Ala, Leu, Asn, Pro and Gln) from larvae in the process of cloning collected in the field with sequences from adults of known species in order to identify asteroid taxa capable of cloning. Neighbor-joining analysis identified four distinct groups of larvae, each having no, or very little, sequence divergence (p distances ranging from 0.00000 to 0.02589); thus, we conclude that each larval group most likely represents a single species. These field-collected larvae cannot …

A Long Way From Home: Transatlantic Sea Star Migration, William Jaeckle, Paul Kehle

Scholarship

For a marine biologist strolling along the eastern coast of South America, finding some sea stars (popularly called starfish, and technically members of the class Asteroidea of the phylum Echinodermata) is not all that unusual. However, when closer inspection reveals the sea stars to be ones that are also found on the shores of the western coast of Africa, the marine biologist now faces an interesting question: How did these sea stars come to be so far from home?

Originally published in Consortiumand used with permission.

A Motor And A Brake: Two Leg Extensor Muscles Acting At The Same Joint Manage Energy Differently In A Running Insect, Anna N. Ahn, Robert J. Full

All HMC Faculty Publications and Research

The individual muscles of a multiple muscle group at a given joint are often assumed to function synergistically to share the load during locomotion. We examined two leg extensors of a running cockroach to test the hypothesis that leg muscles within an anatomical muscle group necessarily manage (i.e. produce, store, transmit or absorb) energy similarly during running. Using electromyographic and video motion-analysis techniques, we determined that muscles 177c and 179 are both active during the first half of the stance period during muscle shortening. Using the in vivo strain and stimulation patterns determined during running, we measured muscle power output. …

Energetics Of Free-Ranging Seabirds, Hugh I. Ellis, Geir Wing Gabrielsen

Biology: Faculty Scholarship

No abstract provided.

Direct Determination Of The Kinetics Of Oxygen Diffusion To The Photocytes Of A Bioluminescent Elaterid Larva, Measurement Of Gas- And Aqueous-Phase Diffusional Barriers And Modelling Of Oxygen Supply, G. S. Timmins, E. J. Bechara, H. M. Swartz

Dartmouth Scholarship

We describe the development and use of a direct kinetic technique to determine the time taken for oxygen to diffuse from the external environment into the light-producing cells (photocytes) in the prothorax of bioluminescent larvae of Pyrearinus termitilluminans. This was achieved by measuring the time course of the pseudoflash induced through sequential anoxia followed by normoxia. We have also determined the separate times taken for this oxygen diffusion in gaseous and tissue (predominantly aqueous) phases by using helium and nitrogen as the carrier gas. Of the total time taken for diffusion, that in the gas phase required 613+/-136 ms (mean …

Measurement Of Oxygen Partial Pressure, Its Control During Hypoxia And Hyperoxia, And Its Effect Upon Light Emission In A Bioluminescent Elaterid Larva, G. S. Timmins, C. A. A. Penatti, E. J. H. Bechara, H. M. Swartz

Dartmouth Scholarship

This study investigates the respiratory physiology of bioluminescent larvae of Pyrearinus termitilluminans in relation to their tolerance to hypoxia and hyperoxia and to the supply of oxygen for bioluminescence. The partial pressure of oxygen (P(O2)) was measured within the bioluminescent prothorax by in vivo electron paramagnetic resonance (EPR) oximetry following acclimation of larvae to hypoxic, normoxic and hyperoxic (normobaric) atmospheres and during periods of bioluminescence (during normoxia). The P(O2) in the prothorax during exposure to an external P(O2) of 15.2, 160 and 760 mmHg was 10.3+/-2.6, 134+/-0.9 and 725+/-73 mmHg respectively (mean +/- s.d., N=5; 1 mmHg=0.1333 kPa). Oxygen supply …

Whole Body I=In Vivo Vascular Compliance In Two Amphibians, Bufo Marinus And Rana Cate, Todd Micheal Hoagland

Dissertations and Theses

The mean circulatory filling pressure (MCFP), vascular compliance (C) and unstressed volume (USV) were measured in Bufo marinus and Rana catesbeiana, using an in vivo preparation. Capacitance curves were constructed by varying total vascular volume and then measuring MCFP. These capacitance curves enable the extrapolation of USV and the measurement of vascular compliance. The MCFP, C, and USV were 8.6 ± 0.2 (mmHg), 3.7 (ml· mmHg-1 · kg- 1 ) and 2.5 (ml), respectively, in B. marinus. The MCFP, C, and USV were 9.5 ± 0.1 (mmHg), 2.2 (ml· mmHg-1 · kg- 1 ) and 14.2 (ml), respectively, …

Arterial Wall Hypertrophy And Pdgf-A Expression In One-Kidney, One-Clip Hypertension And Angiotensin Ii Infusion Are Mediated By Elevated Arterial Pressure, Sheri Blair Parker

Theses and Dissertations in Biomedical Sciences

These studies were designed to characterize the relative roles of angiotensin II (ANG II) and pressure in the structural alterations that occur in experimental hypertension. Two separate studies were performed in order to differentiate these two mechanisms. First, male Wistar rats were subjected to one-kidney, one-clip (1K1C) hypertension or sham operation. Losartan, an AT1 receptor antagonist, was administered chronically to half of each surgical group beginning one day before the operation and continued until the end of the study. In a second experiment, rats were implanted with osmopumps delivering either ANG II or saline. To maintain pressure in the normotensive …