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Osmoregulation in Marine Teleosts. Cl - cells. Image credit: cornell.edu; Karnaky 1986. amazon.co.uk. Image credit: amazon.com. Osmoregulation: Regulation of osmotic pressure of internal fluids. Osmoregulation: Regulation of osmotic pressure of internal fluids Osmosis. - PowerPoint PPT Presentation
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Osmoregulation in MarineTeleosts
Cl- cells
Image credit: cornell.edu; Karnaky 1986
amazon.co.uk
Image credit: amazon.com
Osmoregulation:
• Regulation of osmotic pressure of internal fluids
Osmoregulation:
• Regulation of osmotic pressure of internal fluids• Osmosis
Osmoregulation:
• Regulation of osmotic pressure of internal fluids• Osmosis• Excretion, ingestion, absorption
Three common marine strategies:
1. Osmoconform• Agnathan hagfish & many marine invertebrates• Conform internal [ion] to [external medium]
Three common marine strategies:
1. Osmoconform• Agnathan hagfish & many marine invertebrates• Conform internal [ion] to [external medium]• Evidence of marine origin for vertebrate life?
Image credit: hawaiianatolls.org ; sagepub.com
Image credit: templecuttingedge.files.wordpress.com; abdn.ac.uk; sagepub.com
Three common marine strategies:
2. Osmoconform and ion regulate• Sharks, coelacanth and some amphibians• Plasma concentrations > seawater• NaCl concentration ~ 1/3 seawater
Three common marine strategies:
2. Osmoconform and ion regulate• Sharks• Plasma concentrations > seawater • NaCl concentration ~1/3 seawater• Urea & Trimethylamine N-oxidase (TMAO)• Internal fluids ~5% saltier than seawater
Image credit: templecuttingedge.files.wordpress.com; abdn.ac.uk; sagepub.com
Three common marine strategies:
2. Osmoconform and ion regulate• Sharks• Plasma concentrations > seawater • NaCl concentration ~1/3 seawater• Urea & Trimethylamine N-oxidase (TMAO)• Internal fluids ~5% saltier than seawater
• Rectal gland
Image credit: templecuttingedge.files.wordpress.com; abdn.ac.uk; sagepub.com
Three common marine strategies:
3. Osmoregulate• Teleosts • Regulate Na+ & Cl- ~1/3 seawater• Salt removal• Esophagus• Intestines• Gill chloride cells
Image credit: wikipedia.com; sagepub.com
Other regulators:
• Marine birds/reptiles
• Salt gland• Allows to drink saltwater and consume aquatic
(salty) plants and animals
Image credit: nicerweb.com; wordpress.com
Other regulators:
• Plants – mangroves
1. Roots prevent salt from entering but allow water in2. Excrete salt from glands on leaves3. Concentrate salt in old leaves, flowers, bark
Image credit: wikimedia.org
Three common marine strategies:
Units = mosmol
Solutes Seawater 1) Invertebrates & hagfish
2) Sharks 3) Teleosts
Na+ 470 500 350 180
Cl- 570 500 350 180
Urea 0 0 230 0
TMAO 0 0 170 0
Total 1040 1000 1100 360
Marine teleosts
• The problem• Internal fluids hypotonic to seawater• Constant water loss• Constant ion gain
Image credit: mrupp.info
Marine teleosts
• The problem• Internal fluids hypotonic to seawater• Constant water loss• Constant ion gain
• The answer• Drink constantly• Absorb NaCl and water from ingested seawater• Keep water• Excrete NaCl
Image credit: mrupp.info
How do they pull this off?
Image credit: mrupp.info
How do they pull this off?
American Physiological Society
• August Krogh Distinguished Lectureship
• Bodil Schmidt-Nielsen (1994)
• Jared Diamond (1995)
• Knut Schmidt-Nielsen (1996)
• George Somero (2000)
• Peter Hochachka (2001)
• David Evans (2008)
The characters:
• August Krogh• 1874-1949• Danish• 1920 Nobel Prize
for capillary blood flow
• Gas exchange• Respiration• Diffusion
• Homer Smith• 1896-1962• American• Kidney function
and structure• MDIBL
• Ancel Keys• 1904-2004• American• Krogh’s post-doc
in early 1930s• Influence of diet
on health
Image credit: nndb.com; niehs.nih.gov
The characters:
• August Krogh• 1874-1949• Danish• 1920 Nobel Prize
for capillary blood flow
• Gas exchange• Respiration• Diffusion
• Homer Smith• 1896-1962• American• Kidney function
and structure• MDIBL
• Ancel Keys• 1904-2004• American• Krogh’s post-doc
in early 1930s• Influence of diet
on health
Image credit: nndb.com; niehs.nih.gov
The characters:
• August Krogh• 1874-1949• Danish• 1920 Nobel Prize
for capillary blood flow
• Gas exchange• Respiration• Diffusion
• Homer Smith• 1896-1962• American• Kidney function
and structure• MDIBL
• Ancel Keys• 1904-2004• American• Krogh’s post-doc
in early 1930s• Influence of diet
on health
Image credit: nndb.com; niehs.nih.gov
Basis for question:
• Krogh, Smith, Keys, understood that marine fish were hyposmotic to seawater
• Consequences = dehydrate & gain salts
• How do they regulate against this?
Krogh with freshwater fish:
• Salt uptake from head region
• Probably gills
• Guessed at Cl-/HCO3- & Na+/NH4
+ exchangers
Smith with marine fish:• Continual drinking
• Intestines remove ions and water
• Extrarenal ion elimination pathway• Excess ions excreted through gills?
Image credit: Evans 2008
Keys with marine eels:
• Perfused heart-gill preparation
Image credit: Keys 1931
Keys with marine eels:
• Perfused heart-gill preparation
Image credit: Keys 1931
Keys with marine eels:
• Perfused heart-gill preparation
• Gills site of active Cl- excretion
These studies formed the framework for the model of ion regulation we use today
Image credit: Keys 1931
Chloride Cells - gill morphology
Image credit: imageshack.us; webshots.com
Image credit: Karnaky 1986; webshots.com
Chloride Cells - gill morphology
Chloride Cells
Image credit: Karnaky 1986; Degnan et al. 1977
Chloride Cells - Cl- current & opercular epitheliumChloride Cells - Cl- current & opercular epithelium
Ussing Chamber
Image credit: warneronline.com
Apical(seawater)
Basolateral(blood)
Opercular epithelium
Chloride Cells - Cl- current & opercular epitheliumChloride Cells - Cl- current & opercular epithelium
Ussing Chamber
Image credit: warneronline.com
Apical(seawater)
Basolateral(blood)
Current injection electrodeVoltage
recording electrode
Opercular epithelium
Chloride Cells - Cl- current & opercular epitheliumChloride Cells - Cl- current & opercular epithelium
Ussing Chamber
Image credit: warneronline.com
Apical(seawater)
Basolateral(blood)
Current injection electrodeVoltage
recording electrode
Cl-
Opercular epithelium
Chloride Cells - Cl- current & opercular epithelium
Image credit: Degnan et al. 1977
Chloride Cells - Cl- current & opercular epithelium
Image credit: Degnan et al. 1977
Chloride Cells - Cl- current & opercular epithelium
Image credit: Foskett and Scheffey 1982
Chloride Cells - the mechanism
Image credit: Evans 2008
Chloride Cells - the mechanism
Image credit: Evans 2008
-70 mV
-15 mV
Discussion Questions
• Trade-offs
• Energy required to kep up this process• Why no osmoconform and ion regulate as sharks do?• Euryhaline fish?
• Early, simplistic experimental approaches lost?
Chloride cells - Cystic Fibrosis (CF)• Caused by mutation in CFTR protein• In humans, creates
• sweat• digestive juices• mucous
• CF patients with CFTR failure• Cl- buildup thicker, nutrient-rich mucous in lungs
bacterial infection• Increased Na+ & Cl- uptake decreased water
reabsorption dehydrated thick mucous• Lungs, pancreas, intestine
• Most common fatal, inherited disease in U.S.• Life expectancy = 36 yrs
Three common marine strategies:
1. Osmoconform• Agnathan hagfish & many marine invertebrates• Conform internal [ion] to [external medium]• Blue crab example• Salinity < 28 ppt: regulate• Salinity > 28 ppt: conform
Image credit: flyingfishshop.com