Osmoregulation Immunity Stress and Disease
Jan 11, 2016
OsmoregulationImmunity
Stressand Disease
OsmoregulationImmunity
Stressand Disease
HK
Adrenalin
Head Kidney
CardinalVein Chromaffin
Cells
Brain
Nerve
The Beneficial effects of epinephrine/adrenaline are…
Better “fight or flight” capabilities
• Increases heart rateIncreases heart rate• Increases breathing Increases breathing
(respiration) rate(respiration) rate• Opens gill circulatory systemOpens gill circulatory system• Open muscle circulationOpen muscle circulation• Decreases blood to gutsDecreases blood to guts• Releases sugar from liverReleases sugar from liver
There is no such thing as a free lunch !
Gill Anatomy
Lamella
AfferentArtery
EfferentArtery
AfferentArtery
CartilageRod
Efferent Artery
WaterFlow
Freshwater Fish
Water
Salt
Saltwater Bony Fish
Water
Salt
Saltwater Shark
Water
Salt
=Trimethylamine oxide (TMO) and Urea
Epinephrine makes all osmoregulatory problems
•FW fish gain more water and loose more salt
•Saltwater fish gain more salt and loose more water
•Sharks gain more salt•Hagfish.. well…they stay
hagfish!
worse
•Starvation•Entrapment•Injury•Social problems
Brain
HK
InterrenalCells
ACTHAdrenocorticotropic Hormone
Cortisol
Good Effects of Cortisol ?
•Protein catabolism–Breaks down protein for energy
There is no such thing as a free lunch !
Complement molecules begin to assemble a complex on the wall of a bacterium
Complement finishes forming a channel through the bacterial cell wall.
Lysozyme•Dissolves bacterial cell walls
•Found in–Blood–Mucus–(tears)
Antibodies bind all over a Rhabdovirus and block it from infecting a cell.
Antibodies recognize foreign antigens on an “ich” parasite and mark it for destruction.
Uh-Oh!• Some proteins are really important !
– Antibodies: kill things, flag things for destruction
– Lysozyme: dissolves bacterial cell walls– Complement: pokes holes in bacteria,
flags things for destruction• Macrophages: need those flags• Neutrophils: need those flags• Eosinophils: need those flags
Cortisol Downsides• Cortisol triggers catabolism of
immune system proteins• Cortisol saves scarce resources
by reducing expenditures on immunity– Less white blood cells– Less production of immune proteins
Epinephrine: Makes osmoregulatory problems worse
Cortisol: Screws up the immune
system
The Case
•Bluegills harvested in July
•75-95% die from columnaris infections
The Problem• When fish are loaded onto the
trucks and into raceways, they perceive it as life-threatening
• They make cortisol and epinephrine
• Osmoregulation problems• Immunity problems
The Cure
•No treatment–95% die
•Gentle harvest–90 % die
•Add salt–85% die
•Add penicillin–5% die
The Case•Threadfin shad are harvested and loaded on trucks
•100 % die within 1 hr
The Problem•When threadfin shad are loaded onto the trucks, they perceive it as life-threatening
•They make epinephrine•Osmoregulation problems
The Cure•No treatment
–100 % die•Gentle harvest
–100 % die•Add salt
–95 % die•Add antibiotic
–95% die
The Case•Catfish develop ulcers and die 3-7 days after delivery
•Cultures show common soil bacteria
The Problem•Stress triggered cortisol production
•Cortisol screwed up the immune system
•The fish became susceptible to bacterial infection
What was the stress?•Normal fish: 1,000,000 bacteria
required to cause infection•Oxygen depleted fish: only 100•The neat part: It turns out that the
fish truck had an oxygen accident!•Bacteria levels were probably high
in the pond
The Cure
The Case
• Catfish look normal in aquariums
• Turn rigid if handled• Much worse if fish
aren’t feeding
The Problem•Stress triggered epinephrine release
•The fish had osmoregulatory problems
Why is it a problem here?
•Very low mineral levels in the water
•Minerals from the feed are needed
The Cure
The same thing happens with grass carp:
They are tough in hard waterbut
Fragile in soft water
The same thing happens with grass carp:
They are tough in hard waterbut
Fragile in soft water
Many common procedures used in aquaculture and fisheries are
perceived by fish as life threatening, but really aren’t
•Hauling in trucks•Seining•Weighing•Holding in tanks•Aerator noise…
If the fish make a bunch of epinephrine or cortisol, they
suffer the ill effects, but get no benefit.
The answer is to 1. reduce their perception of danger,
calm them with tranquilizers (if appropriate)
2. deal with the side effects using salt manipulation and antibiotics if appropriate
If conditions really are life threatening…
•Rapid temperature changes•Poor water quality•Handling injuries•Disease
Then, the hormones and their effects are vital to fish
survival…
But, you mustBut, you must
1.help the fish deal with the negative side effects
2.try to reduce improve the dangerous situation
Cures• Epinephrine
– Gentle handling– Salt adjustment for osmoregulation– Tranquilizers1 for open water fish
• Cortisol– Gentle handling and holding– Antibiotics1 for immune problems
1. Use only if required, safe, and LEGAL
Problem - Solution• Epinephrine Epinephrine
– great for fight and great for fight and flightflight
– screws up screws up osmoregulationosmoregulation
• CortisolCortisol– great to provide great to provide
energy in long energy in long lasting emergencieslasting emergencies
– screws up the screws up the immune systemimmune system
• EpinephrineEpinephrine– Gentle handlingGentle handling– Salt adjustment for Salt adjustment for
osmoregulationosmoregulation– Tranquilizers for open Tranquilizers for open
water fishwater fish• CortisolCortisol
– Gentle handlingGentle handling– Antibiotics for immune Antibiotics for immune
problemsproblems