scholarly journals Heat hardening enhances mitochondrial potential for respiration and oxidative defence capacity in the mantle of thermally stressed Mytilus galloprovincialis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ioannis Georgoulis ◽  
Konstantinos Feidantsis ◽  
Ioannis A. Giantsis ◽  
Asimina Kakale ◽  
Christian Bock ◽  
...  
Keyword(s):  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Ros Generation ◽  
Cell Protection ◽  
Cellular Mechanisms ◽  
Mitochondrial Potential ◽  
Defensive Strategies ◽  
Parallel Increase ◽  
Heat Hardening ◽  
Environmental Temperatures

AbstractEctotherms are exposed to a range of environmental temperatures and may face extremes beyond their upper thermal limits. Such temperature extremes can stimulate aerobic metabolism toward its maximum, a decline in aerobic substrate oxidation, and a parallel increase of anaerobic metabolism, combined with ROS generation and oxidative stress. Under these stressful conditions, marine organisms recruit several defensive strategies for their maintenance and survival. However, thermal tolerance of ectothermic organisms may be increased after a brief exposure to sub-lethal temperatures, a process known as "hardening". In our study, we examined the ability of M. galloprovincialis to increase its thermal tolerance under the effect of elevated temperatures (24, 26 and 28 °C) through the "hardening" process. Our results demonstrate that this process can increase the heat tolerance and antioxidant defense of heat hardened mussels through more efficient ETS activity when exposed to temperatures beyond 24 °C, compared to non-hardened individuals. Enhanced cell protection is reflected in better adaptive strategies of heat hardened mussels, and thus decreased mortality. Although hardening seems a promising process for the maintenance of aquacultured populations under increased seasonal temperatures, further investigation of the molecular and cellular mechanisms regulating mussels’ heat resistance is required.

Decay of Thermal Tolerance in Queensland Fruit Fly Eggs (Bactrocera tryoni, Diptera: Tephritidae) Following Non-Lethal Heat Hardening

2019 ◽  
Author(s):  
S D J Brown ◽  
L E Jamieson ◽  
W G Laidlaw ◽  
N de Silva ◽  
B C Waddell
Keyword(s):  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Thermal Conditions ◽  
Fruit Fly ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Bactrocera Tryoni ◽  
Heat Hardening ◽  
Double Exponential ◽  
Lethal Time

Abstract Quarantine disinfestation treatments for Queensland fruit fly (Bactrocera tryoni (Froggatt)) have been developed which use high temperatures to kill preimaginal life stages within fruit prior to export. However, thermal tolerance of individuals can be increased if they are exposed to elevated temperatures before disinfestation treatment. The rate that this thermal conditioning decays after exposure, and the effect of temperature on this decay process, were investigated. Eggs of B. tryoni were exposed to a nonlethal hot water treatment at 38°C for 15 min, 1 or 3 h, then held in air at 25°C for times ranging from 15 min to 12 h, before being exposed to hot water disinfestation at 46°C for various times. From each of these cohorts, the lethal time for 99% mortality (LT99) was calculated. The LT99 of B. tryoni eggs increased with longer conditioning times at 38°C. For each conditioning time, the LT99 decreased with longer delay periods at 25°C prior to disinfestation. The rate of decrease was greatest during the first hour of delay, after which the rate of decrease slowed and tended toward zero. This induction and decay was modeled using a double-exponential equation. These experiments show that thermal conditions prior to disinfestation, and the time delay before the procedure commences, both influence the response of the insect to the disinfestation treatment. These results have implications for the specification of postharvest quarantine treatments, which are usually expressed only in terms of a fruit-center target temperature.

scholarly journals Thermal tolerance of the zoea I stage of four Neotropical crab species (Crustacea: Decapoda)

2018 ◽  
Vol 35 ◽  
pp. 1-5
Author(s):  
Adriana P. Rebolledo ◽  
Rachel Collin
Keyword(s):  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Marine Invertebrates ◽  
Negative Impact ◽  
Larval Survival ◽  
Crab Species ◽  
Marine Habitat ◽  
Mangrove Species ◽  
Larval Stages ◽  
Carry Over

. Although larval stages are often considered particularly vulnerable to stressors, for many marine invertebrates studies of thermal tolerance have focused on adults. Here we determined the upper thermal limit (LT50) of the zoea I of four Caribbean crab species (Macrocoelomatrispinosum, Aratuspisonii, Armasesricordi, and Minucarapax) and compared their thermal tolerance over time and among species. The zoea from the subtidal species M.trispinosum and tree climbing mangrove species A.pisonii had a lower thermal tolerance, 35 and 38.5 °C respectively, than did the semiterrestrial A.ricordi and M.rapax. In all four species tested, the estimates of thermal tolerance depend on the duration of exposure to elevated temperatures. Longer exposures to thermal stress produce lower estimates of LT50, which decreased by ~1 °C from a two- to a six-hour exposure. Crab embryos develop on the abdomen of the mother until the larvae are ready to hatch. Therefore, the thermal tolerances of the embryos which need to coincide with the environmental conditions experienced by the adult stage, may carry over into the early zoea stage. Our results suggest that semiterrestrial species, in which embryos may need to withstand higher temperatures than embryos of subtidal species also produce larvae with higher thermal tolerances. Over the short term, the larvae of these tropical crab species can withstand significantly higher temperatures than those experienced in their marine habitat. Longer term rearing studies are necessary to determine the temperature at which chronic exposure has a negative impact on embryonic and larval survival.

The emerging role of NADPH oxidase NOX5 in vascular disease

2017 ◽  
Vol 131 (10) ◽  
pp. 981-990 ◽  
Author(s):  
Jay C. Jha ◽  
Anna M.D. Watson ◽  
Geetha Mathew ◽  
Lisanne C. de Vos ◽  
Karin Jandeleit-Dahm
Keyword(s):  
Vascular Complications ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Convincing Evidence ◽  
Ros Generation ◽  
Common Denominator ◽  
Cellular Mechanisms ◽  
Pathophysiological Role ◽  
The Common ◽  
Models Of Disease

Oxidative stress is a consequence of up-regulation of pro-oxidant enzyme-induced reactive oxygen species (ROS) production and concomitant depletion of antioxidants. Elevated levels of ROS act as an intermediate and are the common denominator for various diseases including diabetes-associated macro-/micro-vascular complications and hypertension. A range of enzymes are capable of generating ROS, but the pro-oxidant enzyme family, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), are the only enzymes known to be solely dedicated to ROS generation in the vascular tissues, kidney, aortas and eyes. While there is convincing evidence for a role of NOX1 in vascular and eye disease and for NOX4 in renal injury, the role of NOX5 in disease is less clear. Although NOX5 is highly up-regulated in humans in disease, it is absent in rodents. Thus, so far it has not been possible to study NOX5 in traditional mouse or rat models of disease. In the present review, we summarize and critically analyse the emerging evidence for a pathophysiological role of NOX5 in disease including the expression, regulation and molecular and cellular mechanisms which have been demonstrated to be involved in NOX5 activation.

Comparative Effect of Heat Shock on Survival of O157:H7 and Non-O157 Shiga Toxigenic Escherichia coli and Salmonella in Lean Beef with or without Moisture-Enhancing Ingredients

2017 ◽  
Vol 80 (6) ◽  
pp. 1002-1008 ◽  
Author(s):  
Akhila Vasan ◽  
Steven C. Ingham ◽  
Barbara H. Ingham
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Thermal Tolerance ◽  
Pathogenic Bacteria ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
Beef Industry ◽  
Linear Portion ◽  
Beef Products ◽  
Pathogen Control

ABSTRACT Thermal tolerance of pathogenic bacteria has been shown to increase after exposure to sublethal elevated temperatures, or heat shock. We evaluated the effect of heat shock at 48°C on thermal tolerance (D55°C) of cocktails of O157 and non-O157 Shiga toxigenic Escherichia coli (STEC) and Salmonella in lean ground beef with or without moisture-enhancing ingredients. Beef was moisture enhanced to 110% (w) with a 5% NaCl–2.5% sodium tripolyphosphate (w/w) brine. Meat, with or without added brine, was inoculated (∼108 CFU/g) and heat shocked at 48°C for 0, 5, or 30 min, followed by isothermal heating at 55°C. Inoculated control samples were unenhanced and were not subject to heat shock. From the linear portion of the log CFU per gram surviving cells over time plots, D55°C-values (minutes) were calculated. D55°C was 20.43, 28.78, and 21.15 min for O157, non-O157, and Salmonella controls, respectively. Overall, heat shock significantly increased D55°C, regardless of pathogen (P < 0.05). After 30 min of heat shock, D55°C increased 89 and 160% for O157 STEC, 32 and 49% for non-O157 STEC, and 29 and 57% for Salmonella, in unenhanced and enhanced samples, respectively, relative to the pathogen control. D55°C for Salmonella was the same or significantly less than for O157 and non-O157 STEC, regardless of heat shock, and was significantly less than for O157 and non-O157 STEC in all trials with moisture-enhanced meat (P < 0.05). Moisture-enhancing ingredients significantly increased D55°C, regardless of pathogen (P < 0.05). We suggest that thermal processes validated against Salmonella may not prove effective against STEC in all cases and that regulators of the beef industry should focus attention on STEC in nonintact moisture-enhanced beef products.

scholarly journals Comparison of Static and Dynamic Assays When Quantifying Thermal Plasticity of Drosophilids

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 537
Author(s):  
Christian Winther Bak ◽  
Simon Bahrndorff ◽  
Natasja Krog Noer ◽  
Lisa Bjerregaard Jørgensen ◽  
Johannes Overgaard ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Constant Temperature ◽  
Heat Tolerance ◽  
Thermal Tolerance ◽  
Physiological Trait ◽  
Thermal Plasticity ◽  
Heat Hardening ◽  
Temperature Interaction ◽  
Dynamic Assay ◽  
Species Specific

Numerous assays are used to quantify thermal tolerance of arthropods including dynamic ramping and static knockdown assays. The dynamic assay measures a critical temperature while the animal is gradually heated, whereas the static assay measures the time to knockdown at a constant temperature. Previous studies indicate that heat tolerance measured by both assays can be reconciled using the time × temperature interaction from “thermal tolerance landscapes” (TTLs) in unhardened animals. To investigate if this relationship remains true within hardened animals, we use a static assay to assess the effect of heat hardening treatments on heat tolerance in 10 Drosophila species. Using this TTL approach and data from the static heat knockdown experiments, we model the expected change in dynamic heat knockdown temperature (CTmax: temperature at which flies enter coma) and compare these predictions to empirical measurements of CTmax. We find that heat tolerance and hardening capacity are highly species specific and that the two assays report similar and consistent responses to heat hardening. Tested assays are therefore likely to measure the same underlying physiological trait and provide directly comparable estimates of heat tolerance. Regardless of this compliance, we discuss why and when static or dynamic assays may be more appropriate to investigate ectotherm heat tolerance.

scholarly journals Hypersensitivity of excitation-contraction coupling in dystrophic cardiomyocytes

2009 ◽  
Vol 297 (6) ◽  
pp. H1992-H2003 ◽  
Author(s):  
Nina D. Ullrich ◽  
Mohammed Fanchaouy ◽  
Konstantin Gusev ◽  
Natalia Shirokova ◽  
Ernst Niggli
Keyword(s):  
Striated Muscle ◽  
Ryanodine Receptors ◽  
Confocal Imaging ◽  
Mdx Mice ◽  
Ros Generation ◽  
Coupling Mechanism ◽  
Inherited Disease ◽  
Cellular Mechanisms ◽  
Patch Clamp Technique ◽  
Skeletal Muscle Function

Duchenne muscular dystrophy represents a severe inherited disease of striated muscle. It is caused by a mutation of the dystrophin gene and characterized by a progressive loss of skeletal muscle function. Most patients also develop a dystrophic cardiomyopathy, resulting in dilated hypertrophy and heart failure, but the cellular mechanisms leading to the deterioration of cardiac function remain elusive. In the present study, we tested whether defective excitation-contraction (E-C) coupling contributes to impaired cardiac performance. “E-C coupling gain” was determined in cardiomyocytes from control and dystrophin-deficient mdx mice. To this end, L-type Ca2+ currents ( ICaL) were measured with the whole cell patch-clamp technique, whereas Ca2+ transients were simultaneously recorded with confocal imaging of fluo-3. Initial findings indicated subtle changes of E-C coupling in mdx cells despite matched Ca2+ loading of the sarcoplasmic reticulum (SR). However, lowering the extracellular Ca2+ concentration, a maneuver used to unmask latent E-C coupling problems, was surprisingly much better tolerated by mdx myocytes, suggesting a hypersensitive E-C coupling mechanism. Challenging the SR Ca2+ release by slow elevations of the intracellular Ca2+ concentration resulted in Ca2+ oscillations after a much shorter delay in mdx cells. This is consistent with an enhanced Ca2+ sensitivity of the SR Ca2+-release channels [ryanodine receptors (RyRs)]. The hypersensitivity could be normalized by the introduction of reducing agents, indicating that the elevated cellular ROS generation in dystrophy underlies the abnormal RyR sensitivity and hypersensitive E-C coupling. Our data suggest that in dystrophin-deficient cardiomyocytes, E-C coupling is altered due to potentially arrhythmogenic changes in the Ca2+ sensitivity of redox-modified RyRs.

scholarly journals Incubation temperatures, hatching success and congenital anomalies in green turtle nests from Guanahacabibes Peninsula, Cuba

2021 ◽  
Vol 4 (4) ◽  
pp. 321-330
Author(s):  
Randy Calderón Peña ◽  
Julia Azanza Ricardo
Keyword(s):  
Congenital Anomalies ◽  
Green Turtle ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Green Turtles ◽  
Incubation Temperatures

Elevated incubation temperatures of sea turtle nests decrease hatching success and alter the resulting hatchlings' morphology. There is an absence of studies assessing the relationships between temperature and hatching success in Cuba, even when they could improve understanding the limits of thermal tolerance in these species. This study evaluated the influence of incubation temperature on hatching success and phenotypic malformations in green turtle hatchlings (Chelonia mydas); and analyzed the temporal variation in hatching success on the studied beaches. In 48 green turtles nests distributed along two beaches, incubation temperature and hatching success were recorded between 2014 and 2019. Increasing incubation temperature caused a decrease in the hatching success and an increase in the frequency of supernumerary scutes. Despite the elevated temperatures (average > 30°C), hatching was higher than 80%. Significant differences in hatching success were only observed among seasons for nests in Antonio Beach (lower values in 2016 and 2019 compared to 2014).

scholarly journals The Temperature Dependence of Deformation Behaviors in High-Entropy Alloys: A Review

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2005
Author(s):  
Pengfei Wu ◽  
Kefu Gan ◽  
Dingshun Yan ◽  
Zhiming Li
Keyword(s):  
Single Phase ◽  
Elevated Temperatures ◽  
High Entropy Alloys ◽  
Alloy Development ◽  
Temperature Dependent ◽  
High Entropy ◽  
The Past ◽  
Different Temperatures ◽  
Deformation Behaviors ◽  
Environmental Temperatures

Over the past seventeen years, deformation behaviors of various types of high-entropy alloys (HEAs) have been investigated within a wide temperature range, from cryogenic to high temperatures, to demonstrate the excellent performance of HEAs under extreme conditions. It has been suggested that the dominated deformation mechanisms in HEAs would be varied with respect to the environmental temperatures, which significantly alters the mechanical properties. In this article, we systematically review the temperature-dependent mechanical behaviors, as well as the corresponding mechanisms of various types of HEAs, aiming to provide a comprehensive and up-to-date understanding of the recent progress achieved on this subject. More specifically, we summarize the deformation behaviors and microscale mechanisms of single-phase HEAs, metastable HEAs, precipitates-hardened HEAs and multiphase HEAs, at cryogenic, room and elevated temperatures. The possible strategies for strengthening and toughening HEAs at different temperatures are also discussed to provide new insights for further alloy development.

scholarly journals Plasticity in parental effects confers rapid larval thermal tolerance in Nematostella vectensis

2020 ◽  
Author(s):  
Hanny E. Rivera ◽  
Cheng-Yi Chen ◽  
Matthew C. Gibson ◽  
Ann M. Tarrant
Keyword(s):  
North Carolina ◽  
Thermal Tolerance ◽  
Elevated Temperatures ◽  
Thermal Environment ◽  
Larval Mortality ◽  
Nematostella Vectensis ◽  
Parental Effects ◽  
Thermal Thresholds ◽  
Parental Exposure ◽  
Consistent Increase

AbstractParental effects can prepare offspring for different environments and facilitate survival across generations. We exposed parental populations of the estuarine anemone, Nematostella vectensis, from Massachusetts to elevated temperatures and quantified larval mortality across a temperature gradient. We find that parental exposure to elevated temperatures results in a consistent increase in larval thermal tolerance (mean ΔLT50: 0.3°C), and larvae from subsequent spawns return to baseline thermal thresholds when parents are returned to normal temperatures. Histological analyses of gametogenesis in females suggests these dynamic shifts in larval thermal tolerance may be facilitated by maternal effects in non-overlapping gametic cohorts. We also compared larvae from North Carolina (a genetically distinct population with higher baseline thermal tolerance) and Massachusetts parents, and found larvae from heat-exposed Massachusetts parents have thermal thresholds comparable to larvae from unexposed North Carolina parents. North Carolina parents also increased larval thermal tolerance under the same high-temperature regime, suggesting plasticity in parental effects is an inherent trait for N. vectensis. Overall, we find larval thermal tolerance in N. vectensis shows both a strong genetic basis and phenotypic plasticity. Further understanding the mechanisms behind these shifts can elucidate the fate of thermally sensitive ectotherms in a rapidly changing thermal environment.

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