Oxygen in the marine environment Flashcards
Oxygen dead zones
400-plus systems that have scientifically reported accounts of being eutrophication-associated dead zones
what has happened to the number of hypoxic sites per year?
number of reported hypoxic sites per year increases exponentially
why is hypoxia dangerous for aerobic animals?
ATP Levels fall as a result of decreased ATP production
surviving acute hypoxia
attempt to maintain oxygen delivery to tissues by hyperventilating and maintaining or increasing cardiac output
surviving prolonged hypoxia
Oxygen carriage optimised by modifications in the concentration and affinity of extracellular respiratory pigments (haemocyanin or haemoglobin).
Potential hypometabolism, downregulation of protein synthesis and regulatory enzymes.
Eventually, animals must resort to less efficient anaerobic ATP generation (anaerobic metabolism).
consequences of hypoxia
reduction in growth, feeding and fitness
molecular response to hypoxia
glucose transporters to enhance glucose glucose transport- FOR ENHANCED ANAEROBIC RESPIRATION
Increased Enolase production- to enhance glucose uptake and glycolysis
activates gene transcription for erythropoietin enhancement of red blood cell production.
Vascular endothelial growth factor- to enhance proliferation of blood vessels for increasing oxygen supply.
down regulates energy demand- maintain energy balance under low ATP turnover
HIF1- Hypoxia Inducible Factor
DNA-binding heterodimetric transcription factor, composed of alpha and a beta subunit
type of antioxidant defences
enzymes that directly neutralise ROS
- superoxide dismutase (SOD)
- catalase (CAT)
- Glutathione peroxidase (GP)
- peroxiredoxine system
low molecular mass antioxidant
act as radical scavengers and interrupt reactions of radical damage
-metabolites (e.g. glutathione)
- vitamins of dietary origin (e.g. vitamin E, Carotenoids)
