scholarly journals Coupling between fast and slow oscillator circuits in Cancer borealis is temperature-compensated

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Daniel Powell ◽  
Sara A Haddad ◽  
Srinivas Gorur-Shandilya ◽  
Eve Marder
Keyword(s):  
Integer Number ◽  
Temperature Sensitive ◽  
Gastric Mill ◽  
Temperature Dependent ◽  
Cancer Borealis ◽  
Cycle Frequency ◽  
Temperature Changes ◽  
Wide Range ◽  
Similar Temperature ◽  
Increasing Temperature

Coupled oscillatory circuits are ubiquitous in nervous systems. Given that most biological processes are temperature-sensitive, it is remarkable that the neuronal circuits of poikilothermic animals can maintain coupling across a wide range of temperatures. Within the stomatogastric ganglion (STG) of the crab, Cancer borealis, the fast pyloric rhythm (~1 Hz) and the slow gastric mill rhythm (~0.1 Hz) are precisely coordinated at ~11°C such that there is an integer number of pyloric cycles per gastric mill cycle (integer coupling). Upon increasing temperature from 7°C to 23°C, both oscillators showed similar temperature-dependent increases in cycle frequency, and integer coupling between the circuits was conserved. Thus, although both rhythms show temperature-dependent changes in rhythm frequency, the processes that couple these circuits maintain their coordination over a wide range of temperatures. Such robustness to temperature changes could be part of a toolbox of processes that enables neural circuits to maintain function despite global perturbations.

scholarly journals Coupling between fast and slow oscillator circuits in Cancer borealis is temperature compensated

2020 ◽  
Author(s):  
D.J. Powell ◽  
S.A. Haddad ◽  
S. Gorur-Shandilya ◽  
E. Marder
Keyword(s):  
Integer Number ◽  
Temperature Sensitive ◽  
Gastric Mill ◽  
Temperature Dependent ◽  
Cancer Borealis ◽  
Cycle Frequency ◽  
Temperature Changes ◽  
Wide Range ◽  
Similar Temperature ◽  
Increasing Temperature

AbstractCoupled oscillatory circuits are ubiquitous in nervous systems. Given that most biological processes are temperature sensitive, it is remarkable that the neuronal circuits of poikilothermic animals can maintain coupling across a wide range of temperatures. Within the stomatogastric ganglion (STG) of the crab, Cancer borealis, the fast pyloric rhythm (~1Hz) and the slow gastric mill rhythm (~0.1Hz) are precisely coordinated at ~11°C such that there is an integer number of pyloric cycles per gastric mill cycle (integer coupling). Upon increasing temperature from 7-23°C, both oscillators showed similar temperature-dependent increases in cycle frequency, and integer coupling between the circuits was conserved. Thus, although both rhythms show temperature dependent changes in rhythm frequency, the processes that couple these circuits maintain their coordination over a wide range of temperature. Such robustness to temperature changes could be part of a toolbox of processes that enables neural circuits to maintain function despite global perturbations.

scholarly journals Isolation of temperature-sensitive diphtheria toxins in yeast and their effects on Drosophila cells

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 787-796 ◽  
Author(s):  
H.J. Bellen ◽  
D. D'Evelyn ◽  
M. Harvey ◽  
S.J. Elledge
Keyword(s):  
Photoreceptor Cells ◽  
Temperature Sensitive ◽  
Cellular Functions ◽  
Yeast Saccharomyces Cerevisiae ◽  
Similar Temperature Dependence ◽  
Wide Range ◽  
Similar Temperature ◽  
Arrest Growth ◽  
Adp Ribosyltransferase ◽  
Drosophila Cells

We have isolated temperature-sensitive diphtheria toxins (DT-A(ts)) to develop a method that allows temporal impedement of cellular functions. Four DT-A(ts) genes were isolated in a mutagenesis screen using the yeast, Saccharomyces cerevisiae. When expressed in yeast, these DT-A(ts) arrest growth at 18 degrees C but not at 30 degrees C. Three DT-A(ts) were subsequently tested in the R1-R6 photoreceptor cells of transgenic fruit flies, Drosophila melanogaster. The toxins show similar temperature dependence in both organisms, suggesting that they may be useful in a wide range of non-homeothermic species. DNA sequence analysis revealed that three of the four DT-A(ts) mutations are novel. Interestingly, the fourth DT-A(ts) carries the same point mutation as the extensively characterized CRM197, an ADP ribosyltransferase-defective form of diphtheria toxin.

scholarly journals Temperature-dependence of neuronal performance in the motion pathway of the blowfly calliphora erythrocephala

1999 ◽  
Vol 202 (22) ◽  
pp. 3161-3170 ◽  
Author(s):  
A. Warzecha ◽  
W. Horstmann ◽  
M. Egelhaaf
Keyword(s):  
Visual Motion ◽  
Neuronal Response ◽  
Mean Amplitude ◽  
Operating Conditions ◽  
Transient Temperature ◽  
Temperature Dependent ◽  
Calliphora Erythrocephala ◽  
Temperature Changes ◽  
Increasing Temperature ◽  
Relevant Range

Raising the head temperature within a behaviourally relevant range has strong effects on the performance of an identified neuron, the H1 neuron, in the visual motion pathway of blowflies. The effect is seen as an increase in the mean amplitude of the responses to motion under both transient and steady-state conditions, a considerable decrease in the response latency and an improvement in the reliability of the responses to motion. These temperature-dependent effects are independent of whether the animal is exposed to transient temperature changes or is maintained continuously at the same temperature for its entire life. The changes in the neuronal response properties with temperature may be of immediate functional significance for the animal under its normal operating conditions. In particular, the decrease in latency and the improvement in the reliability with increasing temperature may be relevant for the fly when executing its extremely virtuosic flight manoeuvres.

scholarly journals Stability Analysis of Multispan Pipeline Embedded in Temperature-Dependent Matrix

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Nan Wu ◽  
Yongshou Liu ◽  
Guojun Tong ◽  
Jiayin Dai
Keyword(s):  
Natural Frequency ◽  
Critical Velocity ◽  
Critical Pressure ◽  
Dynamic Stiffness ◽  
Second Order ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
First Order ◽  
The Stability ◽  
Increasing Temperature

In this paper, dynamic stiffness method is used to study the stability of multispan pipelines in temperature-dependent matrix. The effects of temperature changes and different span combinations on the natural frequency, critical velocity, and critical pressure of pipelines are discussed. The main conclusions are obtained and shown as follows. The increase of temperature will lead to the decrease of the first three order natural frequencies. The first two order critical velocities and critical pressure of the system will also decrease with increasing temperature. The change of span combination has no influence on the first-order critical velocity and first-order critical pressure of the system, but it has influence on the second order. The influence of the change of span combination on the first-order natural frequency is regular, but that on the second-order and third-order is not. The increase of the velocity will change the instability form of systems with different span combinations, while the change of the pressure inside the tube will not change the instability form of the system.

EFFECT OF AMBIENT TEMPERATURE VARIATION ON PRESSURE DROP DURING CONDENSATION IN LONG INCLINED TUBES

2021 ◽  
pp. 1-24
Author(s):  
Kaipo Kekaula ◽  
Yitung Chen
Keyword(s):  
Pressure Drop ◽  
Ambient Temperature ◽  
Two Phase ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Frictional Pressure Drop ◽  
Wide Range ◽  
Data Points ◽  
Fan Speed ◽  
Increasing Temperature

Abstract Two-phase flow pressure drop during condensation of steam inside inclined tube heat exchangers was investigated over a wide range of ambient temperature. The ambient temperature changes from 3 to 45°C, the steam mass flux varies from 3 to 18 kg/(m2·s), vapor quality ranges from 0.51 to 0.86. 608 data points were experimentally obtained and compared with 8 commonly used correlations from the available literatures. Frictional pressure drop increases with increasing temperature difference and fan speed. For the full experimental dataset, the best overall performing correlation was obtained by using the Wallis correlation (MAPE = 17.60%, NRMSE = 14.87%). For cold ambient temperatures, (Tamb < 20°C, N=298), the best overall performing correlation was obtained by using the Carey correlation (MAPE = 11.02%, NRMSE = 14.71%). For hot ambient temperatures (Tamb >30°C, N = 196), the Lockhart and Martinelli correlation has shown the best performance (MAPE = 16.84%, NRMSE = 20.45%). An improved two-phase frictional pressure drop correlation based on the Wallis correlation [21] is proposed.

scholarly journals Temperature sensitivity differs between heart and red muscle mitochondria in mahi-mahi (Coryphaena hippurus)

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gigi Y. Lau ◽  
Georgina K. Cox ◽  
John D. Stieglitz ◽  
Daniel D. Benetti ◽  
Martin Grosell
Keyword(s):  
Heart Mitochondria ◽  
Effect Of Temperature ◽  
Temperature Sensitive ◽  
Temperature Changes ◽  
Coryphaena Hippurus ◽  
Wide Range ◽  
Irreversible Effects ◽  
Effects Of Temperature ◽  
Lower Temperature

Abstract Maintaining energy balance over a wide range of temperatures is critical for an active pelagic fish species such as the mahi-mahi (Coryphaena hippurus), which can experience rapid changes in temperature during vertical migrations. Due to the profound effect of temperature on mitochondrial function, this study was designed to investigate the effects of temperature on mitochondrial respiration in permeabilized heart and red skeletal muscle (RM) fibres isolated from mahi-mahi. As RM is thought to be more anatomically isolated from rapid ambient temperature changes compared to the myocardium, it was hypothesized that heart mitochondria would be more tolerant of temperature changes through a greater ability to match respiratory capacity to an increase in temperature and to maintain coupling, when compared to RM mitochondria. Results show that heart fibres were more temperature sensitive and increased respiration rate with temperature increases to a greater degree than RM. Respiratory coupling ratios at the three assay temperatures (20, 26, and 30 °C), revealed that heart mitochondria were less coupled at a lower temperature (26 °C) compared to RM mitochondria (30 °C). In response to an in vitro acute temperature challenge, both tissues showed irreversible effects, where both heart and RM increased uncoupling whether the assay temperature was acutely changed from 20 to 30 °C or 30 to 20 °C. The findings from this study indicate that mahi-mahi heart mitochondria were more temperature sensitive compared to those from RM.

scholarly journals Wide-band spectral tuning of heat receptors in the pit organ of the copperhead snake (Crotalinae)

2003 ◽  
Vol 284 (2) ◽  
pp. R598-R606 ◽  
Author(s):  
Vera Moiseenkova ◽  
Brent Bell ◽  
Massoud Motamedi ◽  
Edward Wozniak ◽  
Burgess Christensen
Keyword(s):  
Wide Band ◽  
Threshold Temperature ◽  
Temperature Sensitive ◽  
Spectral Tuning ◽  
Temperature Changes ◽  
Pit Organ ◽  
Wide Range ◽  
The Family ◽  
Low Threshold ◽  
Temperature Receptors

Receptors located in the facial pit organ of certain species of snake signal the presence of prey. Infrared radiation is an effective stimulus suggesting that these receptors may be low-threshold temperature receptors. We recorded from the nerve innervating the pit organ of snakes belonging to the family of Crotalinae while stimulating the receptive area with well-defined optical stimuli. The objective was to determine the sensitivity of these receptors to a wide range (0.400–10.6 μm) of optical stimuli to determine if a temperature-sensitive or photosensitive protein initiated signal transduction. We found that receptors in the pit organ exhibited a unique broad response to a wide range of electromagnetic radiation ranging from the near UV to the infrared. The spectral tuning of these receptors parallels closely the absorption spectra of water and oxyhemoglobin, the predominant chromophore in tissue. Our results support the hypothesis that these are receptors activated by minute temperature changes induced by direct absorption of optical radiation in the thin pit organ membrane.

scholarly journals Phototropin perceives temperature based on the lifetime of its photoactivated state

2017 ◽  
Vol 114 (34) ◽  
pp. 9206-9211 ◽  
Author(s):  
Yuta Fujii ◽  
Hiroyuki Tanaka ◽  
Naotake Konno ◽  
Yuka Ogasawara ◽  
Noriko Hamashima ◽  
...  
Keyword(s):  
Blue Light ◽  
Cellular Response ◽  
Biochemical Properties ◽  
Temperature Sensing ◽  
Temperature Dependent ◽  
Temperature Changes ◽  
Sensing Mechanism ◽  
Similar Temperature ◽  
Living Organisms ◽  
Response To Temperature

Living organisms detect changes in temperature using thermosensory molecules. However, these molecules and/or their mechanisms for sensing temperature differ among organisms. To identify thermosensory molecules in plants, we investigated chloroplast positioning in response to temperature changes and identified a blue-light photoreceptor, phototropin, that is an essential regulator of chloroplast positioning. Based on the biochemical properties of phototropin during the cellular response to light and temperature changes, we found that phototropin perceives temperature based on the temperature-dependent lifetime of the photoactivated chromophore. Our findings indicate that phototropin perceives both blue light and temperature and uses this information to arrange the chloroplasts for optimal photosynthesis. Because the photoactivated chromophore of many photoreceptors has a temperature-dependent lifetime, a similar temperature-sensing mechanism likely exists in other organisms. Thus, photoreceptors may have the potential to function as thermoreceptors.

scholarly journals Neuromodulation enables temperature robustness and coupling between fast and slow oscillator circuits in Cancer borealis

2021 ◽  
Author(s):  
Carola Städele ◽  
Wolfgang Stein
Keyword(s):  
Animal Behavior ◽  
Temperature Response ◽  
Rhythmic Activity ◽  
Projection Neuron ◽  
Broad Temperature Range ◽  
Gastric Mill ◽  
Cancer Borealis ◽  
Temperature Changes ◽  
Temperature Range ◽  
Pattern Generators

Acute temperature changes can disrupt neuronal activity and coordination with severe consequences for animal behavior and survival. Nonetheless, two rhythmic neuronal circuits in the crustacean stomatogastric ganglion (STG) and their coordination are maintained across a broad temperature range. However, it remains unclear how this temperature robustness is achieved. Here, we dissociate temperature effects on the rhythm generating circuits from those of upstream ganglia. We demonstrate that heat-activated factors extrinsic to the rhythm generators are essential to the slow gastric mill rhythm's temperature robustness and contribute to the temperature response of the fast pyloric rhythm. The gastric mill rhythm crashed when only the STG circuits were heated. It could be restored when upstream ganglia were heated in addition, and the activity of the peptidergic modulatory projection neuron (MCN1) increased. Correspondingly, MCN1's neuropeptide transmitter stabilized the rhythm and maintained it over a broad temperature range. Extrinsic neuromodulation is thus essential for the oscillatory circuits in the STG and enables neural circuits to maintain function in temperature-compromised conditions. In contrast, integer coupling between pyloric and gastric mill rhythms was independent of whether extrinsic inputs and STG pattern generators were temperature-matched or not, demonstrating that the temperature robustness of the coupling is enabled by properties intrinsic to the rhythm generators. However, at near-crash temperature, integer coupling was maintained only in some animals but was absent in others. This was true despite regular rhythmic activity in all animals, supporting that degenerate circuit properties result in idiosyncratic responses to environ-mental challenges.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

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