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Temperature

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Articles 91 - 120 of 142

Full-Text Articles in Biology

Influence Of Temperature On The Tensile Strength Of Spider Silk (Araneus Gemmoides), Victoria Lekson Mar 2014

Influence Of Temperature On The Tensile Strength Of Spider Silk (Araneus Gemmoides), Victoria Lekson

Seaver College Research And Scholarly Achievement Symposium

Temperature ranges between day and night in southern California can be as great as 30°C and may influence vital functioning of ectothermic organisms. Arachnids produce silks from a pair of spinnerets in their abdomen and rely on variance in protein composition to make different types of silks. Temperature may influence tensile strength of filaments. We tested the effects of temperature on tensile strength of dragline silk of five specimens of Araneus gemmoides (orb-weaver) which were collected from Malibu Creek State Park in the Santa Monica Mountains of southern California, under five temperature conditions. Each specimen was placed in a 0.0283 …

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Intrinsic And Extrinsic Factors Influence Expression Of Defensive Behavior In Plains Hog‐Nosed Snakes [Abstract], Andrew M. Durso, Stephen J. Mullin Jan 2014

Intrinsic And Extrinsic Factors Influence Expression Of Defensive Behavior In Plains Hog‐Nosed Snakes [Abstract], Andrew M. Durso, Stephen J. Mullin

Faculty Publications

No abstract provided.

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Effect Of Increased Temperature And Decreased Food Quality On Metabolism And Growth Of An Algivorous Cichlid, Tropheus Duboisi And Effect Of Food Habit On The Field Metabolism Of African Cichlids., Lesley Yu-Jung Kim Jan 2014

Effect Of Increased Temperature And Decreased Food Quality On Metabolism And Growth Of An Algivorous Cichlid, Tropheus Duboisi And Effect Of Food Habit On The Field Metabolism Of African Cichlids., Lesley Yu-Jung Kim

Browse all Theses and Dissertations

The metabolic rate of an organism is influenced by mass, temperature, and diet. Climate change is anticipated to increase ambient temperatures of aquatic systems and decrease the quality of food available to algivorous fish. We conducted a lab experiment and a field study to quantify the influence that temperature and diet have on standard and field metabolic rate of cichlids from Lake Tanganyika. The lab experiment demonstrated the effects of increased temperature and decreased food quality on the relative growth rate (RGR) and standard metabolic rate of an algivorous cichlid, Tropheus duboisi. We found that in all temperature treatments fish …

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Changes In Tissue-Specific Fatty Acid Composition Of The Freshwater Alewife (Alosa Pseudoharengus) In Response To Temperature, William D. Schregel Dec 2013

Changes In Tissue-Specific Fatty Acid Composition Of The Freshwater Alewife (Alosa Pseudoharengus) In Response To Temperature, William D. Schregel

Biology Theses

Ectotherms are known to alter the composition of the cell membrane in response to changes in environmental temperature. Tissue-specific fatty acid composition in the alewife (Alosa pseudoharengus) was examined in response to both warm and cold temperature challenges administered over an approximate one month period. Gill, muscle, and liver tissues were analyzed prior to the start of the temperature challenge (initial), following the temperature challenges (survivors), and on those fish that did not survive the temperature challenges (mortalities). Significant differences were found between fatty acid composition of initial fish and survivors for membrane-incorporated fatty acids (polar) and for …

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Differences In Temperature Responses Of Achene Types In Centaurea Melitensis, Kandee L. Bain Nov 2013

Differences In Temperature Responses Of Achene Types In Centaurea Melitensis, Kandee L. Bain

LUX: A Journal of Transdisciplinary Writing and Research from Claremont Graduate University

Southern California has a Mediterranean climate with wet winters and hot dry summers. This type of environment is associated with irregular temperature patterns and rainfall, which can be unpredictable. Unpredictable environments, can threaten the germination and survival of plants like Centaurea melitensis. To ensure germination and survival under unpredictable environmental conditions, some plants may develop characteristic structures like cleistogamous flower heads, and in some cases they will develop heteromorphic achenes. Morphological differences between peripheral and center achenes may indicate variable responses to temperature. Additionally, unpredictable environmental conditions may lead to differences in the number of peripheral to center achenes …

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The Rootscope: A Simple High-Throughput Screening System For Quantitating Gene Expression Dynamics In Plant Roots, Erin J. Kast , '15, Minh-Duyen T. Nguyen , '13, Rosalie E. Lawrence , '12, Christina Rabeler, Nicholas J. Kaplinsky Oct 2013

The Rootscope: A Simple High-Throughput Screening System For Quantitating Gene Expression Dynamics In Plant Roots, Erin J. Kast , '15, Minh-Duyen T. Nguyen , '13, Rosalie E. Lawrence , '12, Christina Rabeler, Nicholas J. Kaplinsky

Biology Faculty Works

Background: High temperature stress responses are vital for plant survival. The mechanisms that plants use to sense high temperatures are only partially understood and involve multiple sensing and signaling pathways. Here we describe the development of the RootScope, an automated microscopy system for quantitating heat shock responses in plant roots.Results: The promoter of Hsp17.6 was used to build a Hsp17.6(p):GFP transcriptional reporter that is induced by heat shock in Arabidopsis. An automated fluorescence microscopy system which enables multiple roots to be imaged in rapid succession was used to quantitate Hsp17.6p: GFP response dynamics. Hsp17.6(p):GFP signal increased with temperature increases from …

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Watering Snakes, Samuel Hirt, Kent Hatch Sep 2013

Watering Snakes, Samuel Hirt, Kent Hatch

Journal of Undergraduate Research

Stable isotope research is a relatively new and innovative tool in ecology. Studies have been done with stable isotopes to determine migration patterns, diet, and evidence for nutritional stress and much more. Little has been done with stable isotopes and reptiles. We conducted a stable isotope, pilot study that will help us understand what happens with snakes in relation to temperature and oxygen and hydrogen turnover ratios in water.

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Do Stable Isotope Turnover Rates In Ectotherm Tissues Change With Temperature?, Joseph Franckum, Kent Hatch Sep 2013

Do Stable Isotope Turnover Rates In Ectotherm Tissues Change With Temperature?, Joseph Franckum, Kent Hatch

Journal of Undergraduate Research

Examining the ratios of stable isotopes (non-decaying atoms with extra neutrons) in animal tissues can yield important information about an organism, such as detecting diet change or establishing migratory origin. Information gathered from these studies help develop future practices to care for certain species. A better understanding of an animal’s dietary capabilities will improve animal techniques.

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Subset Of Heat-Shock Transcription Factors Required For The Early Response Of Arabidopsis To Excess Light, Hou-Sung Jung, Peter A. Crisp, Gonzalo M. Estavillo, Benjamin Cole Aug 2013

Subset Of Heat-Shock Transcription Factors Required For The Early Response Of Arabidopsis To Excess Light, Hou-Sung Jung, Peter A. Crisp, Gonzalo M. Estavillo, Benjamin Cole

Dartmouth Scholarship

Sunlight provides energy for photosynthesis and is essential for nearly all life on earth. However, too much or too little light or rapidly fluctuating light conditions cause stress to plants. Rapid changes in the amount of light are perceived as a change in the reduced/oxidized (redox) state of photosynthetic electron transport components in chloroplasts. However, how this generates a signal that is relayed to changes in nuclear gene expression is not well understood. We modified redox state in the reference plant, Arabidopsis thaliana, using either excess light or low light plus the herbicide DBMIB (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone), a well-known inhibitor of photosynthetic …

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The Effect Of Temperature Extremes On Cardiorespiratory Function In The Grass Shrimp Palaemonetes Pugio: Oxygen Limited Thermal Tolerance, Teresa Mika Aug 2013

The Effect Of Temperature Extremes On Cardiorespiratory Function In The Grass Shrimp Palaemonetes Pugio: Oxygen Limited Thermal Tolerance, Teresa Mika

UNLV Theses, Dissertations, Professional Papers, and Capstones

Aquatic poikilothermic animals must either cope with or compensate for the mismatch in oxygen supply and demand present at high temperatures. Oxygen limited thermal tolerance explains how aerobic scope is limited by insufficient oxygen supply and sets the performance window in animals. This work explores the effects of temperature on the different components of the oxygen delivery system, in both normoxic and hyperoxic conditions to determine if supplying more oxygen to the system mitigates the effects of temperature effects on the cardiorespiratory system and extends oxygen limited thermal tolerance to higher temperatures. The effect of temperature and oxygen condition was …

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Regulation Of Succinate-Fuelled Mitochondrial Respiration In Liver And Skeletal Muscle Of Hibernating Thirteen-Lined Ground Squirrels., Jason C L Brown, Dillon J Chung, Alex N Cooper, James F Staples May 2013

Regulation Of Succinate-Fuelled Mitochondrial Respiration In Liver And Skeletal Muscle Of Hibernating Thirteen-Lined Ground Squirrels., Jason C L Brown, Dillon J Chung, Alex N Cooper, James F Staples

Biology Publications

Hibernating ground squirrels (Ictidomys tridecemlineatus) alternate between two distinct metabolic states throughout winter: torpor, during which metabolic rate (MR) and body temperature (Tb) are considerably suppressed, and interbout euthermia (IBE), during which MR and Tb briefly return to euthermic levels. Previous studies showed suppression of succinate-fuelled respiration during torpor in liver and skeletal muscle mitochondria; however, these studies used only a single, saturating succinate concentration. Therefore, they could not address whether mitochondrial metabolic suppression occurs under physiological substrate concentrations or whether differences in the kinetics of mitochondrial responses to changing substrate concentration might also contribute to mitochondrial metabolic regulation during …

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Are Incomplete Denitrification Pathways A Common Trait In Thermus Species From Geothermal Springs In China?, Julienne J. Paraiso, Brian P. Hedlund Jan 2013

Are Incomplete Denitrification Pathways A Common Trait In Thermus Species From Geothermal Springs In China?, Julienne J. Paraiso, Brian P. Hedlund

McNair Poster Presentations

Temperature has strong impacts on ecosystem function and biogeochemical cycles, particularly within extreme environments such as geothermal springs above 60 °C. The primary focus of this study was to investigate the denitrification pathways of Thermus (Bacteria) isolates from geothermal springs from Tengchong, China. This study tested the hypothesis that incomplete denitrification is a common characteristic of the genus Thermus, regardless of geographic origin or species affiliation, which would implicate them in the efflux of nitrous oxide (a strong greenhouse gas) to the atmosphere. In this study, we cultivated 25 isolates, including six known Thermus species, and measured the stoichiometry …

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Effect Of Rising Temperature Due To Ozone Depletion On The Dynamics Of A Prey-Predator System: A Mathematical Model, O. P. Misra, Preety Kalra Dec 2012

Effect Of Rising Temperature Due To Ozone Depletion On The Dynamics Of A Prey-Predator System: A Mathematical Model, O. P. Misra, Preety Kalra

Applications and Applied Mathematics: An International Journal (AAM)

It is well recognized that the greenhouse gas such as Chlorofluoro Carbon (CFC) is responsible directly or indirectly for the increase in the average global temperature of the Earth. The presence of CFC is responsible for the depletion of ozone concentration in the atmosphere due to which the heat accompanied with the sun rays are less absorbed causing increase in the atmospheric temperature of the Earth. The increase in the temperature level directly or indirectly affects the dynamics of interacting species systems. Therefore, in this paper a mathematical model is proposed and analyzed using stability theory to asses the effects …

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The Effect Of Increased Growth Temperature On Mid-Day And Mid-Night Co2 Fluxes In Populus Deltoids, Rachel Zulick Jul 2012

The Effect Of Increased Growth Temperature On Mid-Day And Mid-Night Co2 Fluxes In Populus Deltoids, Rachel Zulick

Biology ETDs

As global temperatures rise, understanding the effects of increased temperature on daily carbon dioxide fluxes is necessary to predict changes to the global carbon cycle. Using tunable diode laser spectroscopy, I measured CO2 fluxes and changes in isotopic composition of root respiration, leaf respiration and photosynthesis over a 12-hour night to day transition. I found that after a 10°C increase in growth temperature for four weeks, root CO2 fluxes acclimated to the higher temperature (i.e. they were not significantly different from controls). In contrast, both photosynthesis and respiration of leaves were higher at the elevated growth temperature. Though the root …

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Predicting The Physiological Performance Of Ectotherms In Fluctuating Thermal Environments, Michael W. Sears, A C. Niehaus, M J. Angilletta, C E. Franklin, R S. Wilson Feb 2012

Predicting The Physiological Performance Of Ectotherms In Fluctuating Thermal Environments, Michael W. Sears, A C. Niehaus, M J. Angilletta, C E. Franklin, R S. Wilson

Publications

Physiological ecologists have long sought to understand the plasticity of organisms in environments that vary widely among years, seasons and even hours. This is now even more important because human-induced climate change is predicted to affect both the mean and variability of the thermal environment. Although environmental change occurs ubiquitously, relatively few researchers have studied the effects of fluctuating environments on the performance of developing organisms. Even fewer have tried to validate a framework for predicting performance in fluctuating environments. Here, we determined whether reaction norms based on performance at constant temperatures (18, 22, 26, 30 and 34°C) could be …

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Adaptive Tolerance To Ocean Acidification In The Marine Sponge: Chondrilla Nucula, Sylvester Lee Jan 2012

Adaptive Tolerance To Ocean Acidification In The Marine Sponge: Chondrilla Nucula, Sylvester Lee

Electronic Theses and Dissertations

The dramatic increase in atmospheric carbon dioxide since the Industrial Revolution has led to a 30% increase in ocean acidification over pre-industrial levels. Although most ocean acidification research thus far has focused on calcifying organisms such as corals, the potential of this increase in acidity (H+ ions) to cause acid-base imbalances in soft-bodied animals such as sponges has been grossly overlooked. Furthermore, many studies on ocean acidification have not considered the elevated temperatures that are predicted to accompany future climate change conditions. Sponges are crucial components to coral reef systems, providing food, nutrients, structure, and support. The sponge Chondrilla nucula …

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Temperature, Recreational Fishing And Diapause Egg Connections: Dispersal Of Spiny Water Fleas (Bythotrephes Longimanus), W. Charles Kerfoot, Foad Yousef, Martin M. Hobmeier, Ryan P. Maki, S. Taylor Jarnagin, James H. Churchill Nov 2011

Temperature, Recreational Fishing And Diapause Egg Connections: Dispersal Of Spiny Water Fleas (Bythotrephes Longimanus), W. Charles Kerfoot, Foad Yousef, Martin M. Hobmeier, Ryan P. Maki, S. Taylor Jarnagin, James H. Churchill

Michigan Tech Publications, Part 1

The spiny water flea (Bythotrephes longimanus) is spreading from Great Lakes coastal waters into northern inland lakes within a northern temperature-defined latitudinal band. Colonization of Great Lakes coastal embayments is assisted by winds and seiche surges, yet rapid inland expansion across the northern states comes through an overland process. The lack of invasions at Isle Royale National Park contrasts with rapid expansion on the nearby Keweenaw Peninsula. Both regions have comparable geology, lake density, and fauna, but differ in recreational fishing boat access, visitation, and containment measures. Tail spines protect Bythotrephes against young of the year, but not larger fish, …

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Head-Start Juvenile And Adult Resident Eastern Box Turtles (Terrapene Carolina Carolina): Winter Ecology Including Microhabitat Selection, Temperature Tolerance And Philopatry, Amberly Moon Jan 2011

Head-Start Juvenile And Adult Resident Eastern Box Turtles (Terrapene Carolina Carolina): Winter Ecology Including Microhabitat Selection, Temperature Tolerance And Philopatry, Amberly Moon

Theses and Dissertations

The Eastern box turtle (Terrapene carolina carolina) is one of the most common reptiles in North America, but is soon to be threatened due to increased urbanization, disease, and the pet and food trades. In order to assist resource managers in choosing suitable sites for relocation studies, more information on the winter ecology of this species is necessary. We examined the temperature tolerance, microhabitat and degree of philopatry to hibernacula for juvenile and adult E. box turtles for two consecutive winters in Charles City Co, VA. The turtles were tracked via radio telemetry to record point locations during the active …

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Type Ii Protein Arginine Methyltransferase 5 (Prmt5) Is Required For Circadian Pperiod Determination In Arabidopsis Thaliana, Sunghyun Hong, Hae-Ryoung Song, Kerry Lutz, Randall A. Kerstetter, Todd P. Michael, C. Robertson Mcclung Dec 2010

Type Ii Protein Arginine Methyltransferase 5 (Prmt5) Is Required For Circadian Pperiod Determination In Arabidopsis Thaliana, Sunghyun Hong, Hae-Ryoung Song, Kerry Lutz, Randall A. Kerstetter, Todd P. Michael, C. Robertson Mcclung

Dartmouth Scholarship

Posttranslational modification is an important element in circadian clock function from cyanobacteria through plants and mammals. For example, a number of key clock components are phosphorylated and thereby marked for subsequent ubiquitination and degradation. Through forward genetic analysis we demonstrate that protein arginine methyltransferase 5 (PRMT5; At4g31120) is a critical determinant of circadian period in Arabidopsis. PRMT5 is coregulated with a set of 1,253 genes that shows alterations in phase of expression in response to entrainment to thermocycles versus photocycles in constant temperature. PRMT5 encodes a type II protein arginine methyltransferase that catalyzes the symmetric dimethylation of arginine residues (Rsme2). …

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A Comparison Of Cumulative-Germination Response Of Cheatgrass (Bromus Tectorum L.) And Five Perennial Bunchgrass Species To Simulated Field-Temperature Regimes, Stuart P. Hardegree, Corey A. Moffet, Bruce A. Roundy, Thomas A. Jones, Stephen J. Novak, Patrick E. Clark, Frederick B. Pierson, Gerald N. Flerchinger Dec 2010

A Comparison Of Cumulative-Germination Response Of Cheatgrass (Bromus Tectorum L.) And Five Perennial Bunchgrass Species To Simulated Field-Temperature Regimes, Stuart P. Hardegree, Corey A. Moffet, Bruce A. Roundy, Thomas A. Jones, Stephen J. Novak, Patrick E. Clark, Frederick B. Pierson, Gerald N. Flerchinger

Biology Faculty Publications and Presentations

Cheatgrass (Bromus tectorum L.) has come to dominate millions of hectares of rangeland in the Intermountain western United States. Previous studies have hypothesized that one mechanism conferring a competitive advantage to this species is the ability to germinate rapidly at low temperatures in the fall, winter and spring and, therefore, initiate growth and establishment more rapidly than more desirable perennial bunchgrass species. In this experiment, we developed thermal-germination-response models for multiple seedlots of cheatgrass and five perennial grass species. We conducted sensitivity analysis on potentialcumulative- germination response to a 38-y simulation of field-variable conditions of seedbed temperature and moisture. …

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Upper Thermal Tolerances Of Early Life Stages Of Freshwater Mussels, Tamara J. Pandolfo, W. Gregory Cope, Consuelo Arellano, Robert B. Bringolf, M. Christopher Barnhart Jun 2010

Upper Thermal Tolerances Of Early Life Stages Of Freshwater Mussels, Tamara J. Pandolfo, W. Gregory Cope, Consuelo Arellano, Robert B. Bringolf, M. Christopher Barnhart

College of Natural and Applied Sciences

Freshwater mussels (order Unioniformes) fulfill an essential role in benthic aquatic communities, but also are among the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change, industrial discharges, drought, or land development, could further challenge imperiled unionid communities. The aim of our study was to determine the upper thermal tolerances of the larval (glochidia) and juvenile life stages of freshwater mussels. Glochidia of 8 species of mussels were tested: Lampsilis siliquoidea, Potamilus alatus, Ligumia recta, Ellipsaria lineolata, Lasmigona complanata, Megalonaias nervosa, Alasmidonta varicosa, and Villosa delumbis. Seven of these species also …

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Spatial Dynamics Of Nesting Behavior: Lizards Shift Microhabitats To Construct Nests With Beneficial Thermal Properties, Michael W. Sears, Michael J. Angilletta, Robert M. Pringle Oct 2009

Spatial Dynamics Of Nesting Behavior: Lizards Shift Microhabitats To Construct Nests With Beneficial Thermal Properties, Michael W. Sears, Michael J. Angilletta, Robert M. Pringle

Publications

Because temperature affects the growth, development, and survival of embryos,
oviparous mothers should discriminate carefully among available nesting sites. We combined a radiotelemetric study of animal movements with a spatial mapping of environmental temperatures to test predictions about the nesting behavior of the eastern fence lizard (Sceloporus undulatus). Females made large excursions from their typical home ranges to construct nests in exposed substrates. These excursions appeared to be related solely to nesting because all females returned to forested habitat immediately afterward. On average, 1% (range ¼ 0–8%, n ¼ 19) of the area used by a female during nesting was …

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Temperature Effects On Metabolic Rate Of Juvenile Pacific Bluefin Tuna Thunnus Orientalis, Jason M. Blank, Jeffery M. Morrissette, Charles J. Farwell, Mathew Price, Robert J. Schallert, Barbara A. Block Nov 2007

Temperature Effects On Metabolic Rate Of Juvenile Pacific Bluefin Tuna Thunnus Orientalis, Jason M. Blank, Jeffery M. Morrissette, Charles J. Farwell, Mathew Price, Robert J. Schallert, Barbara A. Block

Biological Sciences

Pacific bluefin tuna inhabit a wide range of thermal environments across the Pacific ocean. To examine how metabolism varies across this thermal range, we studied the effect of ambient water temperature on metabolic rate of juvenile Pacific bluefin tuna, Thunnus thynnus, swimming in a swim tunnel. Rate of oxygen consumption (MO2) was measured at ambient temperatures of 8–25°C and swimming speeds of 0.75–1.75 body lengths (BL) s–1. Pacific bluefin swimming at 1 BL s–1 per second exhibited a U-shaped curve of metabolic rate vs ambient temperature, with a thermal minimum zone between …

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The Bertalanffy Growth Equation: Theory Of Paulys Auximetric Plots, Eric L. Charnov Jul 2007

The Bertalanffy Growth Equation: Theory Of Paulys Auximetric Plots, Eric L. Charnov

Biology Faculty & Staff Publications

No abstract provided.

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Effectiveness Of The Entomopathogenic Nematodes Heterorhabditis Bacteriophora And Steinernema Feltiae Against Tenebrio Molitor (Yellow Mealworm) Larvae In Different Soil Types At Different Temperatures, Alper Susurluk Jan 2006

Effectiveness Of The Entomopathogenic Nematodes Heterorhabditis Bacteriophora And Steinernema Feltiae Against Tenebrio Molitor (Yellow Mealworm) Larvae In Different Soil Types At Different Temperatures, Alper Susurluk

Turkish Journal of Biology

The efficiency of the entomopathogenic nematodes Steinernema feltiae Tur-S3 and Heterorhabditis bacteriophora Tur-H2, isolated in Turkey, against larvae of Tenebrio molitor L. was investigated in different soil type and temperature conditions. Sterilized and non-sterilized silver sand, clay-loam soil, and compost soil were tested, each at 12, 18, and 24 ºC. Temperature had the greatest effect on the mortality of T. molitor larvae caused by both nematode species. The efficiency of the 2 nematodes was greater in sterile than in nonsterile conditions, and was greater in sandy soils than in clay soils. The results showed that Steinernema feltiae was more efficient …

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The Relationship Between Frq-Protein Stability And Temperature Compensation In The Neurospora Circadian Clock, Peter Ruoff, Jennifer J. Loros, Jay C. Dunlap Dec 2005

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 …

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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 Feb 2005

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 …

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Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter Dec 2004

Bergmann's Clines In Ectotherms: Illustrating A Life-History Perspective With Sceloporine Lizards, Michael J. Angilletta Jr., Peter H. Niewiarowski, Arthur E. Dunham, Adam D. Leache, Warren P. Porter

Biology Faculty Research

The generality and causes of Bergmann's rule have been debated vigorously in the last few years, but Bergmann's clines are rarely explained in the context of life-history theory. We used both traditional and phylogenetic comparative analyses to explore the causes of latitudinal and thermal clines in the body size of the eastern fence lizard (Sceloporus undulatus). The proximate mechanism for larger body sizes in colder environments is delayed maturation, which results in a greater fecundity but a lower survival to maturity. Life-history theory predicts that a higher survivorship of juveniles in colder environments can favor the evolution of a Bergmann's …

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In Situ Cardiac Performance Of Pacific Bluefin Tuna Hearts In Response To Acute Temperature Change, Jason M. Blank, Jeffery M. Morrissette, Ana M. Landeira-Fernandez, Susanna B. Blackwell, Thomas D. Williams, Barbara A. Block Feb 2004

In Situ Cardiac Performance Of Pacific Bluefin Tuna Hearts In Response To Acute Temperature Change, Jason M. Blank, Jeffery M. Morrissette, Ana M. Landeira-Fernandez, Susanna B. Blackwell, Thomas D. Williams, Barbara A. Block

Biological Sciences

This study reports the cardiovascular physiology of the Pacific bluefin tuna (Thunnus orientalis) in an in situ heart preparation. The performance of the Pacific bluefin tuna heart was examined at temperatures from 30°C down to 2°C. Heart rates ranged from 156 beats min–1 at 30°C to 13 beats min–1 at 2°C. Maximal stroke volumes were 1.1 ml kg–1 at 25°C and 1.3 ml kg–1 at 2°C. Maximal cardiac outputs were 18.1 ml kg–1 min–1 at 2°C and 106 ml kg–1 min–1 at 25°C. These data indicate that cardiovascular function in …

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Temperature-Dependent Oxygen Limitation In Insect Eggs, H. Arthur Woods, Ryan I. Hill Jan 2004

Temperature-Dependent Oxygen Limitation In Insect Eggs, H. Arthur Woods, Ryan I. Hill

College of the Pacific Faculty Articles

Most terrestrial insect embryos support metabolism with oxygen from the environment by diffusion across the eggshell. Because metabolism is more temperature sensitive than diffusion, embryos should be relatively oxygen-limited at high temperatures. We tested whether survival, development time and metabolism of eggs of a moth, Manduca sexta, were sensitive to experimentally imposed variation in atmospheric oxygen availability (5–50 kPa; normoxia at sea level is 21 kPa) across a range of biologically realistic temperatures. Temperature–oxygen interactions were apparent in most experiments. Hypoxia affected survival more strongly at warmer temperatures. Metabolic rates, measured as rates of CO2 emission, were virtually insensitive …

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