Animal Respiration Research Articles

Combining Stressors That Individually Impede Long-Term Memory Blocks All Memory Processes

The effects of stress on memory are typically assessed individually; however, in reality different stressors are often experienced simultaneously. Here we determined the effect that two environmentally relevant stressors, crowding and low calcium availability, have on memory and neural activity following operant conditioning of aerial respiration in the pond snail, Lymnaea stagnalis. We measured aerial breathing behaviour and activity of a neuron necessary for memory formation, right pedal dorsal 1 (RPeD1), in the central pattern generator (CPG) that drives aerial respiration in untrained animals, and assessed how these traits changed following training. In naïve animals both crowding and combined stressors significantly depressed burst activity in RPeD1 which correlated with a depression in aerial breathing behaviour, whereas low calcium availability had no effect on RPeD1 activity. Following training, changes in burst activity in RPeD1 correlated with behavioural changes, decreasing relative to their naïve state at 3 h and 24 h in control conditions when both intermediate-term memory (ITM: 3 h) and long-term memory (LTM: 24 h) are formed, at 3 h but not 24 h when exposed to individual stressors when only ITM is formed, and did not change in combined stressors (i.e. when no memory is formed). Additionally, we also found that Lymnaea formed short-term memory (STM: 10 min) in the presence of individual stressors or under control conditions, but failed to do so in the presence of combined stressors. Our data demonstrate that by combining stressors that individually block LTM only we can block all memory processes. Therefore the effects of two stressors with similar individual affects on memory phenotype may be additive when experienced in combination.

Oxygen radical formation in anoxic transgression and anoxia-reoxygenation: Foe or phantom? Experiments with a hypoxia tolerant bivalve

Intertidal blue mussels, Mytilus edulis, experience hypoxia reoxygenation during tidal emersion and resubmersion cycles, and this is often suggested to represent a major stress for the animals, especially for their respiratory tissues, the gills. We exposed mussels to experimental short and prolonged anoxia and subsequent reoxygenation and analyzed the respiratory response in excised gill tissue and the effects of treatment on reactive oxygen species (mainly ROS: superoxide anion, O2·− and hydrogen peroxide, H2O2), formation using live imaging techniques and confocal microscopy. Our aim was to understand if this “natural stress” would indeed produce oxidative damage and whether antioxidant defenses are induced under anoxia, to prevent oxidative damage during reoxygenation. Exposure to declining pO2 in the respiration chamber caused an increase of gill metabolic rate between 21 and 10 kPa, a pO2 range in which whole animal respiration is reported to be oxyregulating. Exposure of the animals to severe anoxia caused an onset of anaerobiosis (succinate accumulation) and shifted high and low critical pc values (pc1: onset of oxyregulation in gills, pc2: switch from oxyregulation to oxyconformity) to higher pO2. Concentrations of both ROS decreased strongly during anoxic exposure of the mussels and increased upon reoxygenation. This ROS burst induced lipid peroxidation in the mantle, but neither were protein carbonyl levels increased (oxidative damage in the protein fraction), nor did the tissue glutathione concentration change in the gills. Further, analysis of apoptosis markers indicated no induction of cell death in the gills. To our knowledge, this is the first paper that directly measures ROS formation during anoxia reoxygenation in mussels. We conclude that hypoxia tolerant intertidal mussels do not suffer major oxidative stress in gill and mantle tissues under these experimental conditions.

MRI compatible small animal monitoring and trigger system for whole body scanners

Performing magnetic resonance imaging (MRI) experiments with small animals requires continuous monitoring of vital parameters, especially the respiration rate. Clinical whole-body MR scanners represent an attractive option for preclinical imaging as dedicated animal scanners are cost-intensive in both investment and maintenance, thus limiting their availability. Even though impressive image quality is achievable with clinical MR systems in combination with special coils, their built-in physiologic monitoring and triggering units are often not suited for small animal imaging. In this work, we present a simple, MRI compatible low cost solution to monitor the respiration and heart rate of small animals in a clinical whole-body MR scanner. The recording and processing of the biosignals as well as the optimisation of the respiratory trigger generation is decribed. Additionally rat and mouse in-vivo MRI experiments are presented to illustrate the effectiveness of the monitoring and respiratory trigger system in suppressing motion artifacts.

Jellyfish Body Plans Provide Allometric Advantages beyond Low Carbon Content

Jellyfish form spectacular blooms throughout the world’s oceans. Jellyfish body plans are characterised by high water and low carbon contents which enables them to grow much larger than non-gelatinous animals of equivalent carbon content and to deviate from non-gelatinous pelagic animals when incorporated into allometric relationships. Jellyfish have, however, been argued to conform to allometric relationships when carbon content is used as the metric for comparison. Here we test the hypothesis that differences in allometric relationships for several key functional parameters remain for jellyfish even after their body sizes are scaled to their carbon content. Data on carbon and nitrogen contents, rates of respiration, excretion, growth, longevity and swimming velocity of jellyfish and other pelagic animals were assembled. Allometric relationships between each variable and the equivalent spherical diameters of jellyfish and other pelagic animals were compared before and after sizes of jellyfish were standardised for their carbon content. Before standardisation, the slopes of the allometric relationships for respiration, excretion and growth were the same for jellyfish and other pelagic taxa but the intercepts differed. After standardisation, slopes and intercepts for respiration were similar but excretion rates of jellyfish were 10× slower, and growth rates 2× faster than those of other pelagic animals. Longevity of jellyfish was independent of size. The slope of the allometric relationship of swimming velocity of jellyfish differed from that of other pelagic animals but because they are larger jellyfish operate at Reynolds numbers approximately 10× greater than those of other pelagic animals of comparable carbon content. We conclude that low carbon and high water contents alone do not explain the differences in the intercepts or slopes of the allometric relationships of jellyfish and other pelagic animals and that the evolutionary longevity of jellyfish and their propensity to form blooms is facilitated by their unique body plans.

Soil carbon dynamics: The effects of nitrogen input, intake demand and off-take by animals

Elucidation of the drivers of soil carbon (C) change is required to enable decisions to be made on how to achieve soil C sequestration. Interactions between different components in the ecosystem in combination with feedback mechanisms mean that identifying drivers through conventional experimental approaches or by retro-fitting models to data are unlikely to result in the insights needed for the future.This paper explains soil C dynamics by using a process-based model. Drivers considered in the model include nitrogen (N) fertiliser inputs, intake demand, and off-take of animal products. The effect of the grazing animal in uncoupling the C and N cycles is explained, plus the implications of the farming system (‘drystock’ versus milk). The model enables depiction of the dynamic equilibrium achieved with time when a proposed change in the drivers is sustained. The results show that soil C loss under lactating cows is a result of N, rather than C, being removed in milk. Counter-intuitively, at the same intake demand, N loss under ‘milk’ is less than under ‘dry-stock’, as is C loss in animal respiration. Possibilities for changing the longevity of C in the soil are discussed, and the compromise between food production, N loss and C sequestration is considered.

Vasoconstriction in horses caused by endophyte-infected tall fescue seed is detected with Doppler ultrasonography1

The hypotheses that endophyte (Neotyphodium coenophialum)-infected tall fescue (TF) seed causes vasoconstriction in horses in vivo and that ground seed would cause more pronounced vasoconstriction than whole seed were tested. Ten horses each received 1 of 3 treatments: endophyte-free ground (E-G; n = 4 horses) seed, endophyte-positive whole (E+W; n = 3) seed, or endophyte-positive ground (E+G; n = 3) seed. There were two 14-d periods, P1 and P2. During P1, animals were adapted to a concentrate (0.2% BW, as fed, twice daily) and alfalfa cubes. During P2, the seed was mixed into the concentrate portion of the diet and alfalfa cubes were offered ad libitum. Fescue seed was fed in increasing amounts ranging from 0.02% BW on d 1 (averaging 76 ug/kg ergovaline + ergovalinine) to 0.22% BW on d 11 to 14 (averaging 713 ug/kg ergovaline + ergovalinine). The distal palmar artery of the left foreleg of each horse was scanned via Doppler ultrasonography for 4 d during each period, with 5 replicate scans performed on each scanning day. The measurements taken at each scan included artery luminal diameter, area, and circumference, peak systolic velocity, end diastolic velocity and blood flow variables. Animal temperature, heart rate, and respiration rate and ambient temperature and humidity were also recorded. Blood samples were taken on each scanning day to measure inflammatory cytokine mRNA abundances, and blood samples were collected on d 0, 4, 8, and 14 of P2 to measure prolactin concentrations. Consumption of E+G TF seed caused decreased artery lumen diameter (P = 0.0033), area (P = 0.0406), and circumference (P = 0.0480) compared with E-G seed, and E+W seed produced an intermediate response. Blood flow volume was reduced (P < 0.05) during P2 in horses receiving E+G seed compared with horses receiving E-G seed. Other ultrasound variables were not different (P > 0.05) among treatment groups, and neither were cytokine mRNA or prolactin concentrations. Treatment did not alter (P > 0.05) animal temperature, heart rate, or respiration rate, and neither ambient temperature nor relative humidity was consistently correlated with any response variable measured. Taken together, these data confirm that consumption of E+G fescue seed caused vasoconstriction in horses, which could be readily measured by Doppler ultrasonography. Use of Doppler ultrasound to monitor the diameter of the palmar artery of horses grazing endophyte-infected (E+) fescue pastures may provide a convenient and satisfactory biomarker to determine premonitory signs of fescue toxicosis.

АПНОЙНАЯ ОКСИГЕНАЦИЯ

Recent technological advances in thoracic and tracheal surgery make the anaesthesiologist use different respiratory techniques during the operation. Apneic oxygenation is a one of alternative techniques. This method is relatively easy in use, does not require special expensive equipment and is the only possible technique in several clinical situations when other respiratory methods are undesirable or cannot be used. However there is no enough information about apneic oxygenation in Russian. This article reviews publications about apneic oxygenation. The review deals with experiments on diffusion respiration in animals, physiological changes during apneic oxygenation in man and defines clinical cases when apneic oxygenation can be used.

Regional Sympathetic Blockade Attenuates Activation of Intestinal Macrophages and Reduces Gut Barrier Failure

Endotoxin-induced activation of monocytes may lead to extravasation of cells, excessive production of nitric oxide, and subsequent epithelial injury in the gut. Regional sympathetic blockade by means of thoracic epidural anesthesia has been implicated to protect the epithelial barrier. This study tested the hypothesis that thoracic epidural anesthesia decreases epithelial permeability by attenuating monocytic production of nitric oxide and nitrosative stress. Rats were anesthetized, hemodynamically monitored, and mechanically ventilated. Endotoxemia was induced by an intravenous bolus injection of Escherichia coli lipopolysaccharide. Either lidocaine 2% or normal saline was injected as a bolus, followed by a continuous infusion via an epidural catheter. Three hundred minutes after injection of lipopolysaccharide or normal saline, gut epithelial permeability to fluorescein isothiocyanate-dextran (4 kDa), intestinal expression of inducible nitric oxide synthase by macrophages, and lipid peroxidation represented by 8-isoprostane tissue concentration were quantified. Thoracic epidural anesthesia significantly attenuated the endotoxin-induced increases in gut epithelial permeability (437 [293, 492] vs. 628 [532, 1,042] ng/ml, median [quartiles], P = 0.03), expression of nitric oxide synthase (2 [1,2] vs. 7 [5,8] cells per 384 µm(2), P = 0.003), macrophage infiltration, and lipid peroxidation (22,460 ± 11,476 vs. 37,840 ± 17,551 pg/ml, mean ± SD, P = 0.05). Thoracic epidural anesthesia attenuates endotoxin-induced gut epithelial injury. This is likely due to a decrease in monocytic extravasation and intestinal nitrosative stress. As possible mechanisms, direct nerve-immune interplay, a reduction in plasma catecholamines, or a systemic lidocaine effect has to be considered.

Measurement of benthic photosynthesis and calcification in flowing‐through seawater with stable carbonate chemistry

Estimation of photosynthetic or calcification rates of benthic organisms under stable seawater chemistry is important to fathom their capacity of CO2 fixation under constant or controlled levels of pCO2 and acidity of seawater. The flowing‐through system, introduced here, can hold large individuals or colonies and maintain the carbonate chemical parameters stable while photosynthetic or calcification rate is measured based on the assimilation pipe inlet and outlet differences in dissolved O2 concentrations or total alkalinity. The data obtained with this system for macroalgae showed constancy over time under controlled conditions, resulting in higher photosynthetic rates compared with those measured in a closed mode, which caused significant changes in the carbonate system (decreased pCO2 and DIC and increased pH). When the method was applied to measurements of calcification based on the changes in total alkalinity, reliable data were obtained for both coralline algae and oysters. In addition, it can also be applied to measure respiration of both macrophyte and animals and to test the effects of increased pCO2 and current speeds when these factors are controlled under either laboratory or field conditions while exposed to natural solar radiation.

Methane emissions from sheep pasture, measured with an open‐path eddy covariance system

AbstractMethane (CH4) is an important greenhouse gas, contributing 0.4–0.5 W m−2 to global warming. Methane emissions originate from several sources, including wetlands, rice paddies, termites and ruminating animals. Previous measurements of methane flux from farm animals have been carried out on animals in unnatural conditions, in laboratory chambers or fitted with cumbersome masks. This study introduces eddy covariance measurements of CH4, using the newly developed LI‐COR LI‐7700 open‐path methane analyser, to measure field‐scale fluxes from sheep grazing freely on pasture. Under summer conditions, fluxes of methane in the morning averaged 30 nmol m−2 s−1, whereas those in the afternoon were above 100 nmol m−2 s−1, and were roughly two orders of magnitude larger than the small methane emissions from the soil. Methane emissions showed no clear relationship with air temperature or photosynthetically active radiation, but some diurnal pattern was apparent, probably linked to sheep grazing behaviour and metabolism. Over the measurement period (days 60–277, year 2010), cumulative methane fluxes were 0.34 mol CH4 m−2, equating to 134.3 g CO2 equivalents m−2. By comparison, a carbon dioxide (CO2) sink of 819 g CO2 equivalents m−2 was measured over the same period, but it is likely that much of this would be released back to the atmosphere during the winter or as off‐site losses (through microbial and animal respiration). By dividing methane fluxes by the number of sheep in the field each day, we calculated CH4 emissions per head of livestock as 7.4 kg CH4 sheep−1 yr−1, close to the published IPCC emission factor of 8 kg CH4 sheep−1 yr−1.

Experimental study on variations of CO2 concentration in the presence of indoor plants and respiration of experimental animals

This study aims to suggest an improved experimental method to reveal the ability of indoor plants to reduce CO2 concentrations, as well as to display the individual CO2 reduction characteristics of various indoor plants in accordance with this improved method. In previous studies, experiments were conducted under the condition in which the CO2 concentration in the experimental chamber is set only once to a high initial level of 1,000 ppm. However, in real conditions, CO2 concentration gradually increases in a room after the occupants enter. Hence, the existing experimental method can be improved in view of “light saturation and CO2 compensation”. Accordingly, in this study, the CO2 reduction characteristics of indoor plants under 2 conditions used in the existing method of measurement (Case 1) and the condition in the new method, which considers that CO2 concentration gradually increases through the respiration of experimental animals (Case 2)-were measured and compared against each other. For all plant samples, the level of CO2 reduction was higher in Case 2 than in Case 1, and the rate of CO2 reduction increases with time. The inflection point of CO2 concentration appeared at leaf areas of 9,000 cm2 in peace lily and areca palm, and 6,000 cm2 in weeping fig.

Energy Budget for the Cultured, Zooxanthellate Octocoral Sinularia flexibilis

The zooxanthellate octocoral Sinularia flexibilis is a producer of potential pharmaceutically important metabolites such as antimicrobial and cytotoxic substances. Controlled rearing of the coral, as an alternative for commercial exploitation of these compounds, requires the study of species-specific growth requirements. In this study, phototrophic vs. heterotrophic daily energy demands of S. flexibilis was investigated through light and Artemia feeding trials in the laboratory. Rate of photosynthetic oxygen by zooxanthellae in light (≈200 μmol quanta m⁻² s⁻¹) was measured for the coral colonies with and without feeding on Artemia nauplii. Respiratory oxygen was measured in the dark, again with and without Artemia nauplii. Photosynthesis-irradiance curve at light intensities of 0, 50, 100, 200, and 400 μmol quanta m⁻² s⁻¹ showed an increase in photosynthetic oxygen production up to a light intensity between 100 and 200 μmol quanta m⁻² s⁻¹. The photosynthesis to respiration ratio (P/R > 1) confirmed phototrophy of S. flexibilis. Both fed and non-fed colonies in the light showed high carbon contribution by zooxanthellae to animal (host) respiration values of 111-127%. Carbon energy equivalents allocated to the coral growth averaged 6-12% of total photosynthesis energy (mg C g⁻¹ buoyant weight day⁻¹ and about 0.02% of the total daily radiant energy. "Light utilization efficiency (ε)" estimated an average ε value of 75% 12 h⁻¹ for coral practical energetics. This study shows that besides a fundamental role of phototrophy vs. heterotrophy in daily energy budget of S. flexibilis, an efficient fraction of irradiance is converted to useable energy.

Effects of forage chicory (Cichorium intybus) and perennial ryegrass (Lolium perenne) on methane emissions in vitro and from sheep

Published reports of CH4 yields as g CH4/kg dry matter (DM) intake suggest that emissions from sheep fed fresh forage chicory (Cichorium intybus) are about 30% lower than from those fed fresh ryegrass. In this study, 2 year old wethers (16; 54±3.8kg liveweight) were fed either mature chicory or perennial ryegrass at 1.3 times maintenance metabolisable energy requirements in the late spring/early summer of 2009. Methane emissions were determined using individual animal respiration chambers. Feeds differed in their chemical composition with chicory containing 856g/kg organic matter (OM), 117g/kg crude protein (CP) and 281g/kg neutral detergent fibre (aNDF), whereas ryegrass contained 916g/kg OM, 85g/kg CP and 499g/kg aNDF. The DM intake was similar for both forages at 0.76kg/d, and CH4 yields did not differ between forages being 22.8 and 23.8g CH4/kg DM intake for chicory and ryegrass, respectively. In vitro incubations of chicory and perennial ryegrass in the vegetative or mature states had similar CH4 yields. Despite large differences in chemical composition, especially aNDF, chicory and ryegrass had similar CH4 yields in vitro and in vivo. Chicory is not a viable alternative to perennial ryegrass for mitigating CH4 in pastoral based sheep production systems.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

An Assessment of Soil Properties under Different Landuse Types of the Kallada River Basin, Kerala, India

A thin layer of soil covers most of the earth's land surface. This layer varying from a few centimeters to 2 or 3 meters in thickness might appear insignificant relative to the bulk of the earth. On the basis of morphological features and physico chemical properties, the soils of the Kallada basin can be classified into broad six groups (1) Coastal alluviam 2) Riverine alluviam 3) Brown hydromorphic 4) Greyish Onattukara soil 5) Laterite soil and 6)Forest loam (GSI Map). Twenty four soil profiles were collected from the Kallada river basin for analysis, whose 12 profiles are in one cluster distributed adjoining the Western Ghats crest. As many as 12 profiles were under forest, three under grasslands, three under teak plantations, two under mixed tree crops, two under tea plantation and one each from eucalyptus and rubber plantations. Soil is a rich but fragile ecosystem. It is a three-phase system, composed of solid, liquid and gaseous phases. In most soils, the solid phase makes up the vast majority of the soil mass, and over half of its volume. It consists of mineral matter derived from the weathering of rocks and organic matter from the decomposition of plants and animals. The liquid phase is composed predominantly of water, enriched with dissolved solids, the gaseous phase of air, enriched with carbon dioxide from the respiration of soil animals and plant roots. Physical properties of the soil are determined by the character of solid particles and the way in which they are packed together.

Heterotrophy in the Mediterranean symbiotic coral Cladocora caespitosa: comparison with two other scleractinian species

This experimental study assessed the grazing rates of the Mediterranean symbiotic coral Cladocora caespitosa on the 4 main food sources available in its natural environment: detrital partic- ulate organic matter (DPOM) and pico-, nano-, and microzooplankton. These rates were compared to the rates of 2 other scleractinian symbiotic species, the Mediterranean coral Oculina patagonica and the tropical coral Turbinaria reniformis. Results showed that C. caespitosa was the species with the highest grazing rates of pico- and nanoplankton, which contributed to more than half of the carbon supplied by photosynthesis. The daily heterotrophic carbon (C) input from these prey (at in situ con- centrations) was 88.3 ± 22.9, 16.9 ± 8.2, and 17.6 ± 4.3 µg C cm -2 d -1 for C. caespitosa, O. patagonica, and T. reniformis, respectively, corresponding to a percent contribution of heterotrophically acquired C to daily animal respiration (CHAR) of 119.8, 28.7, and 15.9%, respectively. C. caespitosa was also able to derive a significant part of its carbon needs from the grazing of microzooplankton and DPOM. Indeed, considering the in situ concentrations, the daily heterotrophic C input from microzoo- plankton and DPOM would be 32.6 and 10.0 µg C cm -2 d -1 , giving a CHAR estimation of 44.2 and 13.6%, respectively. Heterotrophy therefore plays a major role in the energy budget of this temper- ate species.

Reshaping of Bulbar Odor Response by Nasal Flow Rate in the Rat

BackgroundThe impact of respiratory dynamics on odor response has been poorly studied at the olfactory bulb level. However, it has been shown that sniffing in the behaving rodent is highly dynamic and varies both in frequency and flow rate. Bulbar odor response could vary with these sniffing parameter variations. Consequently, it is necessary to understand how nasal airflow can modify and shape odor response at the olfactory bulb level.Methodology and Principal FindingsTo assess this question, we used a double cannulation and simulated nasal airflow protocol on anesthetized rats to uncouple nasal airflow from animal respiration. Both mitral/tufted cell extracellular unit activity and local field potentials (LFPs) were recorded. We found that airflow changes in the normal range were sufficient to substantially reorganize the response of the olfactory bulb. In particular, cellular odor-evoked activities, LFP oscillations and spike phase-locking to LFPs were strongly modified by nasal flow rate.ConclusionOur results indicate the importance of reconsidering the notion of odor coding as odor response at the bulbar level is ceaselessly modified by respiratory dynamics.

Mitochondrial physiology of diapausing and developing embryos of the annual killifish Austrofundulus limnaeus: implications for extreme anoxia tolerance

Diapausing embryos of the annual killifish Austrofundulus limnaeus have the highest reported anoxia tolerance of any vertebrate and previous studies indicate modified mitochondrial physiology likely supports anoxic metabolism. Functional mitochondria isolated from diapausing and developing embryos of the annual killifish exhibited VO(2), respiratory control ratios (RCR), and P:O ratios consistent with those obtained from other ectothermic vertebrate species. Reduced oxygen consumption associated with dormancy in whole animal respiration rates are correlated with maximal respiration rates of mitochondria isolated from diapausing versus developing embryos. P:O ratios for developing embryos were similar to those obtained from adult liver, but were diminished in mitochondria from diapausing embryos suggesting decreased oxidative efficiency. Proton leak in adult liver corresponded with that of developing embryos but was elevated in mitochondria isolated from diapausing embryos. In metabolically suppressed diapause II embryos, over 95% of the mitochondrial oxygen consumption is accounted for by proton leak across the inner mitochondrial membrane. Decreased activity of mitochondrial respiratory chain complexes correlates with diminished oxidative capacity of isolated mitochondria, especially during diapause. Respiratory complexes exhibited suppressed activity in mitochondria with the ATP synthase exhibiting the greatest inhibition during diapause II. Mitochondria isolated from diapause II embryos are not poised to produce ATP, but rather to shuttle carbon and electrons through the Kreb's cycle while minimizing the generation of a proton motive force. This particular mitochondrial physiology is likely a mechanism to avoid production of reactive oxygen species during large-scale changes in flux through oxidative phosphorylation pathways associated with metabolic transitions into and out of dormancy and anoxia.

Temperature sensitivity of cardiac mitochondria in intertidal and subtidal triplefin fishes

The heart is acutely sensitive to temperature in aquatic ectotherms and appears to fail before any other organ as the thermal maximum is reached, although the exact cause of this failure remains unknown. The heart is highly aerobic and therefore dependent on mitochondrial oxidative phosphorylation (OXPHOS) to meet energy requirements, but the role of cardiac mitochondria in limiting heart function at high temperatures remains unclear. We used permeabilised ventricle fibres to explore heart mitochondrial function in situ in three closely related species of small New Zealand triplefin fishes in response to temperature. We compared this to measures of whole animal respiration rates and critical oxygen tensions in these fishes. Bellapiscis medius, an intertidal species, had the greatest tolerance to hypoxia at higher temperatures and had more efficient OXPHOS at 30°C than the two subtidal species Forsterygion varium and F. malcolmi. B. medius also displayed the highest cytochrome c oxidase flux, which may in part explain how B. medius tolerates higher temperatures and hypoxia. Triplefin heart mitochondria exhibit decreased coupling to phosphorylation with increasing temperature. This most likely impairs ATP supply to the heart at elevated temperatures, potentially contributing to heart failure at ecologically relevant temperatures.

High Resolution Cerebral Blood Flow Imaging by Registered Laser Speckle Contrast Analysis

Laser speckle imaging (LSI) has been widely used for in vivo detecting cerebral blood flow (CBF) under various physiological and pathological conditions. So far, nearly all literature on in vivo LSI does not consider the influence of disturbances due to respiration and/or heart beating of animals. In this paper, we analyze how such physiologic motions affect the spatial resolution of the conventional laser speckle contrast analysis (LASCA). We propose a registered laser speckle contrast analysis (rLASCA) method which first registers raw speckle images with a 3 x 3 convolution kernel, normalized correlation metric and cubic B-spline interpolator, and then constructs the contrast image for CBF. rLASCA not only significantly improves the distinguishability of small vessels, but also efficiently suppresses the noises induced by respiration and/or heart beating. In an application of imaging the angiogenesis of rat's brain tumor, rLASCA outperformed the conventional LASCA in providing a much higher resolution for new small vessels. As a processing method for LSI, rLASCA can be directly applied to other LSI experiments where the disturbances from different sources (like respiration, heart beating) exist.

Learning to Encode Timing: Mechanisms of Plasticity in the Auditory Brainstem

Mechanisms of plasticity have traditionally been ascribed to higher-order sensory processing areas such as the cortex, whereas early sensory processing centers have been considered largely hard-wired. In agreement with this view, the auditory brainstem has been viewed as a nonplastic site, important for preserving temporal information and minimizing transmission delays. However, recent groundbreaking results from animal models and human studies have revealed remarkable evidence for cellular and behavioral mechanisms for learning and memory in the auditory brainstem.