scholarly journals The role of mechanistic physiology in investigating impacts of global warming on fishes

2021 ◽  
Vol 224 (Suppl 1) ◽  
pp. jeb238840
Author(s):  
Sjannie Lefevre ◽  
Tobias Wang ◽  
David J. McKenzie
Keyword(s):  
Thermal Performance ◽  
Thermal Tolerance ◽  
Specific Dynamic Action ◽  
Fish Growth ◽  
Aerobic Scope ◽  
Physiological Tolerance ◽  
Performance Curves ◽  
Supply Capacity ◽  
Underlying Mechanisms

ABSTRACTWarming of aquatic environments as a result of climate change is already having measurable impacts on fishes, manifested as changes in phenology, range shifts and reductions in body size. Understanding the physiological mechanisms underlying these seemingly universal patterns is crucial if we are to reliably predict the fate of fish populations with future warming. This includes an understanding of mechanisms for acute thermal tolerance, as extreme heatwaves may be a major driver of observed effects. The hypothesis of gill oxygen limitation (GOL) is claimed to explain asymptotic fish growth, and why some fish species are decreasing in size with warming; but its underlying assumptions conflict with established knowledge and direct mechanistic evidence is lacking. The hypothesis of oxygen- and capacity-limited thermal tolerance (OCLTT) has stimulated a wave of research into the role of oxygen supply capacity and thermal performance curves for aerobic scope, but results vary greatly between species, indicating that it is unlikely to be a universal mechanism. As thermal performance curves remain important for incorporating physiological tolerance into models, we discuss potentially fruitful alternatives to aerobic scope, notably specific dynamic action and growth rate. We consider the limitations of estimating acute thermal tolerance by a single rapid measure whose mechanism of action is not known. We emphasise the continued importance of experimental physiology, particularly in advancing our understanding of underlying mechanisms, but also the challenge of making this knowledge relevant to the more complex reality.

scholarly journals Oxygen supply capacity in animals evolves to meet maximum demand at the current oxygen partial pressure regardless of size or temperature

2019 ◽  
Author(s):  
Brad A. Seibel ◽  
Curtis Deutsch
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Thermal Tolerance ◽  
Oxygen Supply ◽  
Cardiovascular Health ◽  
Hypoxia Tolerance ◽  
Aerobic Scope ◽  
Supply Capacity

AbstractPhysiological oxygen supply capacity is associated with athletic performance and cardiovascular health and is thought to cause hypometabolic scaling in diverse species. Environmental oxygen is widely believed to be limiting of metabolic rate and aerobic scope, setting thermal tolerance and body size limits with implications for species diversity and biogeography. Here we derive a quantifiable linkage between maximum and basal metabolic rate and their temperature, size and oxygen dependencies. We show that, regardless of size or temperature, the capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure which, for most species assessed, is the current atmospheric pressure. Any reduction in oxygen partial pressure from current values will result in a decrement in maximum metabolic performance. However, oxygen supply capacity does not constrain thermal tolerance and does not cause hypometabolic scaling. The critical oxygen pressure, typically viewed as an indicator of hypoxia tolerance, instead reflects adaptations for aerobic scope. This simple new relationship redefines many important physiological concepts and alters their ecological interpretation.One sentence summary: Metabolism is not oxygen limited

scholarly journals Integrating patterns of thermal tolerance and phenotypic plasticity with population genetics to improve understanding of vulnerability to warming in a widespread copepod

2019 ◽  
Author(s):  
Matthew C. Sasaki ◽  
Hans G. Dam
Keyword(s):  
Gene Flow ◽  
Phenotypic Plasticity ◽  
Local Adaptation ◽  
Thermal Performance ◽  
Thermal Tolerance ◽  
Thermal Adaptation ◽  
Florida Keys ◽  
High Latitudes ◽  
High Dispersal ◽  
Performance Curves

AbstractDifferences in population vulnerability to warming are defined by spatial patterns in thermal adaptation. These patterns may be driven by natural selection over spatial environmental gradients, but can also be shaped by gene flow, especially in marine taxa with high dispersal potential. Understanding and predicting organismal responses to warming requires disentangling the opposing effects of selection and gene flow. We begin by documenting genetic divergence of thermal tolerance and developmental phenotypic plasticity. Ten populations of the widespread copepodAcartia tonsawere collected from sites across a large thermal gradient, ranging from the Florida Keys to Northern New Brunswick, Canada (spanning over 20 degrees latitude). Thermal performance curves from common garden experiments revealed local adaptation at the sampling range extremes, with thermal tolerance increasing at low latitudes and decreasing at high latitudes. The opposite pattern was observed in phenotypic plasticity, which was strongest at high latitudes. Over a large portion of the sampled range, however, we observed a remarkable lack of differentiation of thermal performance curves. To examine whether this lack of divergence is the result of selection for a generalist performance curve or constraint by gene flow, we analyzed cytochrome oxidase I mtDNA sequences, which revealed abundant genetic diversity and widely-distributed haplotypes. Strong divergence in thermal performance within genetic clades, however, suggests that the pace of thermal adaptation can be relatively rapid. The combined insight from the laboratory physiological experiments and genetic data indicate that gene flow constrains differentiation of thermal performance curves. This balance between gene flow and selection has implications for patterns of vulnerability to warming. Taking both genetic differentiation and phenotypic plasticity into account, our results suggest that local adaptation does not increase vulnerability to warming, and that low latitude populations in general may be more vulnerable to predicted temperature change over the next century.

scholarly journals Thermal performance curves for aerobic scope in a tropical fish (Lates calcarifer): flexible in amplitude but not breadth

2021 ◽  
Author(s):  
Hanna Scheuffele ◽  
Francesc Rubio-Gracia ◽  
Timothy D. Clark
Keyword(s):  
Thermal Performance ◽  
Growth Rates ◽  
Daily Temperature ◽  
Tropical Fish ◽  
Metabolic Phenotype ◽  
Performance Curve ◽  
Aerobic Scope ◽  
Lates Calcarifer ◽  
Thermal Performance Curve ◽  
Performance Curves

Aerobic metabolic scope is a popular metric to estimate the capacity for temperature-dependent performance in aquatic animals. Despite this popularity, little is known of the role of temperature acclimation and variability in shaping the breadth and amplitude of the thermal performance curve for aerobic scope. If daily thermal experience can modify the characteristics of the thermal performance curve, interpretations of aerobic scope data from the literature may be misguided. Here, tropical barramundi (Lates calcarifer) were acclimated for ∼4 months to cold (23℃), optimal (29℃) or warm (35℃) conditions, or to a daily temperature cycle between 23 and 35℃ (with a mean of 29℃). Measurements of aerobic scope were conducted every 3-4 weeks at three temperatures (23℃, 29℃ and 35℃), and growth rates were monitored. Acclimation to constant temperatures caused some changes in aerobic scope at the three measurement temperatures via adjustments in standard and maximal metabolic rates, and growth rates were lower in the 23℃-acclimated group compared with all other groups. The metabolic parameters and growth rates of the thermally variable group remained similar to those of the 29℃-acclimated group. Thus, acclimation to a variable temperature regime did not broaden the thermal performance curve for aerobic scope. We propose that aerobic scope thermal performance curves are more plastic in amplitude rather than breadth, and that the metabolic phenotype of at least some fish may be more dependent on the mean daily temperature rather than on the daily temperature range.

Response Interference as a Mechanism Underlying Implicit Measures

2008 ◽  
Vol 24 (4) ◽  
pp. 218-225 ◽  
Author(s):  
Bertram Gawronski ◽  
Roland Deutsch ◽  
Etienne P. LeBel ◽  
Kurt R. Peters
Keyword(s):  
Task Performance ◽  
Psychological Research ◽  
Implicit Measures ◽  
Mediation Model ◽  
Response Interference ◽  
Relevant Evidence ◽  
Moderated Mediation Model ◽  
Stimulus Features ◽  
Underlying Mechanisms

Over the last decade, implicit measures of mental associations (e.g., Implicit Association Test, sequential priming) have become increasingly popular in many areas of psychological research. Even though successful applications provide preliminary support for the validity of these measures, their underlying mechanisms are still controversial. The present article addresses the role of a particular mechanism that is hypothesized to mediate the influence of activated associations on task performance in many implicit measures: response interference (RI). Based on a review of relevant evidence, we argue that RI effects in implicit measures depend on participants’ attention to association-relevant stimulus features, which in turn can influence the reliability and the construct validity of these measures. Drawing on a moderated-mediation model (MMM) of task performance in RI paradigms, we provide several suggestions on how to address these problems in research using implicit measures.

The More You Say, the Less They Hear

2015 ◽  
Vol 27 (4) ◽  
pp. 159-169 ◽  
Author(s):  
Elsbeth D. Asbeek Brusse ◽  
Marieke L. Fransen ◽  
Edith G. Smit
Keyword(s):  
Hearing Protection ◽  
Entertainment Education ◽  
Mediating Role ◽  
Attitude Measures ◽  
Underlying Mechanisms

Abstract. This study examined the effects of disclosure messages in entertainment-education (E-E) on attitudes toward hearing protection and attitude toward the source. In addition, the (mediating) role of the underlying mechanisms (i.e., transportation, identification, and counterarguing) was studied. In an experiment (N = 336), three different disclosure messages were compared with a no-disclosure condition. The results show that more explicit disclosure messages negatively affect transportation and identification and stimulate the generation of counterarguments. In addition, the more explicit disclosure messages affect both attitude measures via two of these processes (i.e., transportation and counterarguing). Less explicit disclosure messages do not have this effect. Implications of the findings are discussed.

THE ROLE OF AN ELECTRICALLY HEATED FRONT COVER ON THE THERMAL PERFORMANCE OF A RADIATOR

2017 ◽  
Vol 44 (5) ◽  
pp. 409-425
Author(s):  
Francesco Corvaro ◽  
Maurizio Benucci ◽  
Barbara Marchetti ◽  
Roberta Cocci Grifoni ◽  
Fabio Polonara
Keyword(s):  
Thermal Performance ◽  
Front Cover

Autophagy Modulators and Neuroinflammation

2020 ◽  
Vol 27 (6) ◽  
pp. 955-982 ◽  
Author(s):  
Kyoung Sang Cho ◽  
Jang Ho Lee ◽  
Jeiwon Cho ◽  
Guang-Ho Cha ◽  
Gyun Jee Song
Keyword(s):  
Neurodegenerative Disorders ◽  
Neurological Disorders ◽  
Mammalian Cells ◽  
Critical Role ◽  
Therapeutic Agents ◽  
Mechanisms Of Action ◽  
Scientific Interest ◽  
Therapeutic Tools ◽  
Underlying Mechanisms

Background: Neuroinflammation plays a critical role in the development and progression of various neurological disorders. Therefore, various studies have focused on the development of neuroinflammation inhibitors as potential therapeutic tools. Recently, the involvement of autophagy in the regulation of neuroinflammation has drawn substantial scientific interest, and a growing number of studies support the role of impaired autophagy in the pathogenesis of common neurodegenerative disorders. Objective: The purpose of this article is to review recent research on the role of autophagy in controlling neuroinflammation. We focus on studies employing both mammalian cells and animal models to evaluate the ability of different autophagic modulators to regulate neuroinflammation. Methods: We have mostly reviewed recent studies reporting anti-neuroinflammatory properties of autophagy. We also briefly discussed a few studies showing that autophagy modulators activate neuroinflammation in certain conditions. Results: Recent studies report neuroprotective as well as anti-neuroinflammatory effects of autophagic modulators. We discuss the possible underlying mechanisms of action of these drugs and their potential limitations as therapeutic agents against neurological disorders. Conclusion: Autophagy activators are promising compounds for the treatment of neurological disorders involving neuroinflammation.

Inflammatory Biomarkers in Atrial Fibrillation

2019 ◽  
Vol 26 (5) ◽  
pp. 837-854 ◽  
Author(s):  
Effimia Zacharia ◽  
Nikolaos Papageorgiou ◽  
Adam Ioannou ◽  
Gerasimos Siasos ◽  
Spyridon Papaioannou ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Plasma Levels ◽  
Large Scale ◽  
Inflammatory Biomarkers ◽  
Inflammatory Pathways ◽  
Inflammatory State ◽  
Anti Inflammatory ◽  
Underlying Mechanisms

During the last few years, a significant number of studies have attempted to clarify the underlying mechanisms that lead to the presentation of atrial fibrillation (AF). Inflammation is a key component of the pathophysiological processes that lead to the development of AF; the amplification of inflammatory pathways triggers AF, and, in tandem, AF increases the inflammatory state. Indeed, the plasma levels of several inflammatory biomarkers are elevated in patients with AF. In addition, the levels of specific inflammatory biomarkers may provide information regarding to the AF duration. Several small studies have assessed the role of anti-inflammatory treatment in atrial fibrillation but the results have been contradictory. Large-scale studies are needed to evaluate the role of inflammation in AF and whether anti-inflammatory medications should be routinely administered to patients with AF.

Inter-Tissue and Intra-Tissue Co-Expression Networks in Human Metabolism: Morphological Evaluation of the Link Between Transcription Factors ERβ and NFAT in Morbid Obesity

2020 ◽  
Vol 17 (1) ◽  
pp. 63-80
Author(s):  
Athina Chasapi ◽  
Kostas Balampanis ◽  
Eleni Kourea ◽  
Fotios Kalfaretzos ◽  
Vaia Lambadiari ◽  
...  
Keyword(s):  
Morbid Obesity ◽  
Adipose Tissue ◽  
Clinicopathological Parameters ◽  
Morbidly Obese ◽  
Human Metabolism ◽  
Activated T Cells ◽  
Alcoholic Fatty Liver ◽  
Morphological Evaluation ◽  
Underlying Mechanisms

Background: Estrogen receptor β (ERβ) plays an important role in human metabolism and some of its metabolic actions are mediated by a positive “cross-talk” with Nuclear Factor of Activated T cells (NFAT) and the key metabolic transcriptional coregulator Transcriptional Intermediary Factor 2 (TIF2). Introduction: Our study is an “in situ” morphological evaluation of the communication between ERβ, NFAT and TIF2 in morbid obesity. Potential correlations with clinicopathological parameters and with the presence of diabetes and non-alcoholic fatty liver disease (NAFLD) were also explored. The aim of the present study was to determine the role of ERβ and NFAT in the underlying pathophysiology of obesity and related comorbidities. We have investigated the expression of specific proteins using immunochemistry methodologies. Methods: Our population consists of 50 morbidly obese patients undergoing planned bariatric surgery, during which biopsies were taken from visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), skeletal muscle (SM), extramyocellular adipose tissue (EMAT) and liver and the differential protein expression was evaluated by immunohistochemistry. Results: We demonstrated an extensive intra- and inter-tissue co-expression network, which confirms the tissue-specific and integral role of each one of the investigated proteins in morbid obesity. Moreover, a beneficial role of ERβ and NFATc1 against NAFLD is implicated, whereas the distinct roles of TIF2 still remain an enigma. Conclusions: We believe that our findings will shed light on the complex underlying mechanisms and that the investigated biomarkers could represent future targets for the prevention and therapy of obesity and its comorbidities.

scholarly journals GPER-Deficient Rats Exhibit Lower Serum Corticosterone Level and Increased Anxiety-Like Behavior

2020 ◽  
Vol 2020 ◽  
pp. 1-22 ◽  
Author(s):  
Yi Zheng ◽  
Meimei Wu ◽  
Ting Gao ◽  
Li Meng ◽  
Xiaowei Ding ◽  
...  
Keyword(s):  
Hpa Axis ◽  
Corticosterone Level ◽  
Brain Structures ◽  
Ample Evidence ◽  
Genetic Ablation ◽  
Serum Corticosterone ◽  
Underlying Mechanisms ◽  
G Protein Coupled ◽  
Prolonged Stress

Ample evidence suggests that estrogens have strong influences on the occurrence of stress-related mood disorders, but the underlying mechanisms remain poorly understood. Through multiple approaches, we demonstrate that the G protein-coupled estrogen receptor (GPER) is widely distributed along the HPA axis and in brain structures critically involved in mood control. Genetic ablation of GPER in the rat resulted in significantly lower basal serum corticosterone level but enhanced ACTH release in response to acute restraint stress, especially in the female. GPER-/- rats of either sex displayed increased anxiety-like behaviors and deficits in learning and memory. Additionally, GPER deficiency led to aggravation of anxiety-like behaviors following single-prolonged stress (SPS). SPS caused significant decreases in serum corticosterone in WT but not in GPER-deficient rats. The results highlight an important role of GPER at multiple sites in regulation of the HPA axis and mood.

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