Temperature and hypoxia

What refers to the noxious stimuli that an individual is exposed to in stress?

Stress.

What physiological and behavioral responses are considered part of the stress response?

Coping responses to stressors.

What can result from the overstimulation of coping responses?

Disease.

What is the modern definition of stress?

Any internal/external challenge that threatens homeostasis of cells or organisms.

What impacts organisms directly through temperature?

Temperature stress.

What drives fitness in organisms in relation to environmental stress?

Optimal environmental range.

What is the main purpose of the stress response?

To maintain homeostasis.

What is the cellular stress response triggered by?

Severe acute stress.

What are the four cornerstones of the cellular stress response?

Repair and prevention of damage, activation of cell cycle checkpoints, mobilization of energy, decisions on apoptosis.

What is the heat shock response (HSR)?

A quality control system that repairs and prevents protein unfolding.

What assists in the folding of proteins maintaining their function?

Heat shock proteins (HSPs).

What term refers to proteins that help stabilize unfolded proteins?

Molecular chaperones.

How do heat shock proteins (HSPs) act during cellular stress?

By assisting with protein folding and preventing aggregation.

What is the significance of Hsp70?

It assists misfolded proteins and targets malformed proteins for degradation.

What common factor affects HSP expression according to thermal histories?

Acclimatization and thermal regimes experienced in nature.

What are the implications of hypoxia on ATP production?

ATP levels fall due to decreased aerobic ATP production.

What are oxyconformers and oxyregulators?

Types of organisms that either conform to environmental oxygen levels or regulate oxygen delivery.

Which transcription factor is vital for cellular responses to hypoxia?

Hypoxia inducible factor (HIF).

What does HIF do in response to low oxygen levels?

Control gene expression to promote survival.

How is ROS produced in organisms?

As byproducts of normal mitochondrial metabolism.

What can increased ROS and impaired antioxidant defenses lead to?

Oxidative stress.

What is the result of the discrepancy in ROS generation during hypoxia?

Increased mitochondrial ROS generation despite reduced metabolic activity.

What is the effect of prolonged hypoxia on metabolic functions?

Reduction in growth, feeding, and fitness.

What do glucose transporters do during hypoxia?

Enhance glucose transport to maintain ATP production.

Which enzyme enhances glycolysis during hypoxia?

Enolase.

What happens when animals are exposed to reoxygenation after hypoxia?

High ROS production requiring increased antioxidant defenses.

Why is hypoxia dangerous for aerobic animals?

It disrupts ion homeostasis and can lead to cell death.

What is a potential HSP diagnostic marker for thermal stress?

HSP expression patterns.

How do environmental acclimatization responses vary in species?

Based on typical thermal regimes experienced in their habitats.

What can result from chronic stress exposure in cells?

Constitutive overexpression of heat shock proteins.

What adaptation mechanism do marine ectotherms show to hypoxia?

Reduced metabolic rate (hypometabolism).

In what species was hypoxia-induced gene expression observed?

Gillichthys mirabilis.

What did research show about G. mirabilis during hypoxia?

Up-regulation of anaerobic ATP production genes.

What is the significance of transcription factors during hypoxia?

They initiate cellular adjustments and may signal physiological conditioning.

What can hypoxia do to gene expression patterns in aquatic organisms?

Lead to widespread changes and adaptative responses.

How do species differ in their responses to hypoxia?

Different vulnerabilities to hypoxia reflect in different underlying mechanisms.

What happens to energy metabolism under prolonged hypoxia?

Animals revert to anaerobic ATP generation.

What is an example of a common consequence for aquatic organisms subjected to low oxygen levels?

Increased mortality in sensitive larval stages.

What factor enhances the gene transcription of erythropoietin during hypoxia?

Hypoxia inducible factor (HIF-1).

How has hypoxia affected animal populations in marine environments?

Increased stress responses in populations at the edges of their range.

What ecological significance do HSP levels have in animals from different environmental ranges?

Indicates stress levels and adaptability.

What is the role of antioxidant defenses in combating oxidative stress?

To detoxify reactive oxygen species (ROS) and reduce oxidative damage.

What do glucose transporters do during hypoxia?

Enhance glucose transport to maintain ATP production.

Which enzyme enhances glycolysis during hypoxia?

Enolase.

What are some examples of glycolytic enzymes?

Hexokinase, lactate dehydrogenase, pyruvate kinase, and phosphofructokinase.

What is the role of Erythropoietin (EPO) in mammals and fish during hypoxia?

HIF-1 activates gene transcription for erythropoietin, enhancing red blood cell production.

What does Vascular endothelial growth factor do?

Enhance proliferation of blood vessels for increasing oxygen supply.

How do transcription factors help maintain energy balance under low ATP turnover?

They down-regulate energy demand to maintain energy balance.

What is the first cornerstone of the cellular stress response?

Repair and prevention of macromolecular damage, including DNA, protein, and membrane lipids.

Why is the activation of cell cycle checkpoints crucial in the cellular stress response?

It induces growth arrest to save energy, allows time for repair, and prevents the multiplication and transmission of damaged genomes or proteomes to future generations.

What is the purpose of mobilizing and reallocating metabolic energy during the cellular stress response?

To redirect energy towards macromolecular repair and stabilization.

What is the role of programmed cell death (apoptosis) as a cornerstone of the cellular stress response?

To protect multicellular organisms from irreversible and pathological damage.