The document discusses fish hemoglobin and its characteristics. It notes that fish hemoglobin has multiple components that vary in amino acid composition, oxygen affinity, and other properties. This allows fish to adapt to different environmental conditions. Fish hemoglobin is found within red blood cells and is a tetrameric globular protein containing heme groups that can bind oxygen. The oxygen affinity of fish hemoglobin can change based on factors like pH, carbon dioxide levels, temperature, and organic phosphates. The document also describes the root effect, where fish hemoglobin has greatly reduced oxygen affinity at low pH, allowing oxygen to be released into tissues.

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2. Contents:
1. Introduction
2. Gas Exchange
3. Haemoglobin: Fish Vs Mammal
4. Fish haemoglobin characteristics
5. Haemoglobin of fish Erthyocytes
6. Structure of fish haemoglobin
7. Different haemoglobin Types
8. Developmental changes
9. Blood oxygen affinity
10. Root effect : 1. Description
2. Significance
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3. 1. The name hemoglobin is derived from the words heme and globin, reflecting
the fact that each subunit of hemoglobin is a globular protein with an
embedded heme group.
2. Each heme group contains one iron atom, that can bind one oxygen molecule
through ion-induced dipole forces.
3. The most common type of hemoglobin in mammals contains four such
subunits.
4. Hemoglobin or haemoglobin; abbreviated Hb or Hgb, is the iron-containing
oxygen-transport metalloprotein in the red blood cells of almost all vertebrates
as well as the tissues of some invertebrates.
Intoduction
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4. 5. Hemoglobin in the blood carries oxygen from the lungs or gills to the rest of the
body
6. Found in all vertebrates with the exception of the fish family channichthyidae
(white-blooded fish)
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 One of the major physiological challenges facing all multicellular animals is obtaining
sufficient oxygen and disposing of excess carbon dioxide
 In vertebrates, the gases diffuse into the aqueous layer covering the epithelial cells that line
the respiratory organs
 Diffusion is passive, driven only by the difference in O2 and CO2 concentrations on the two
sides of the membranes and their relative solubilities in the plasma membrane
Gas Exchange

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 Gases diffuse directly into unicellular organisms
 However, most multicellular animals require system adaptations to
enhance gas exchange
 Amphibians respire across their skin
 Insects have an extensive tracheal system
 Mammals have a large network of alveoli
 Fish use gills

7. Haemoglobin : Fish Vs Mammal
1. The fish Hbs autooxidize and release hemin ∼50 to 100-fold more rapidly than bovine Hb.
2. The susceptibility of fish Hbs to oxidative degradation is high compared to mammalian
Hbs.
3. Lys(E10) is found in most mammalian Hb and forms favorable electrostatic and hydrogen
bonding interactions with the heme-7-propionate. In contrast, Thr(E10) is present in most
fish Hbs and is too short to stabilize bound heme, and causes increased rates of hemin
dissociation
4. The generally rapid rates of lipid oxidation in fish muscle can be partly attributed to the fact
that fish Hbs are highly susceptible to oxidative degradation
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8. Fish Hemoglobin Characteristics
 The major features of telost fish haemoglobin is Hb multiplicity.
 The term hemoglobin multipilicity means the occurrence of more than one
hemoglobin components in the same or different developmental stage
 Hemoglobin multiplicity has been regarded as an important adaptive strategy
for fish to vary environmental conditions and for changing metabolic
requirements.
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9. • May differ in many features
– Composition of amino acids
– Affinity for oxygen
– Some salmonids have up to 18 different Hbs
 Many notothenids possess only two hemoglobins . One major
hemoglobin (90-95%) of mass and second minor component (5-10%) of
total mass
 Both components are functionally indistinguishable which suggest that
the minor one is an evolutionary reminant without physiological
significance .
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10. Hemoglobin (Hb) of Fish Erythrocytes
 Hemoglobins are particularly important in fish adaptation as they
constitute an interface between the organism and the Environment.
 Tetrameric molecule
 molecular wight 60,000-70,000Da
 Consists of four globin chains- two alpha and two beta chains
 Globin chains have 140-160 amino acids (Mol. wt, 15000 and 17, 000
Da)
 Serves to make the binding of oxygen to haem-iron reversible
 Haem is situated in a hydrophobic pocket of globin
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11.  In some fish up to 15% may be in plasma
 A few fish have no Hb (rare situation)
The Icefish of the Antarctic
( Family : Channichthyidae)
- high solubility of oxygen in water
-Low metabolic requirements.
-Special cardiovascular adaptations .
(larger blood vessel , greater blood
Volume, bigger heart, greater cardiac
output)
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Fish Blood : in general
Fish Blood : Ice Fish

12. Fish Haemoglobins structure
• Structure is different in different fish
– Monomeric :
Single-heme peptide molecules
Found in Agnatha (lamprey, hag
fish)
• Tetrameric :
– Four peptide chains
for eg. gold fish , eel
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13. Having Different Hemoglobin Types
• The seversal forms of haemoglobins present in fish species called Isohaemoglobins.
• Different Hbs have different responses to:
- temperature
- oxygen affinity
- size of Bohr’s effect
• Allows fish to deal with changing conditions
– Important for migratory species
 Some fish gain or lose types as they age
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14. Developmental changes
 Ontogenetic changes in fish haemoglobin components have been observed in three
species of lamprey , the dogfish ,the skate , the teleost, and four species of salmon.
 The ammocoete larva of the lamprey, Petromyzon planeri, has two major components
which are replaced after metamorphosis with two different components .
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15. BLOOD OXYGEN AFFINITY
• pH
– Decreasing pH decreases Hb affinity for O2
– Often associated with carbon dioxide
• Carbon dioxide
– Increase in CO2 drives off O2 (Bohr effect)
– Decrease in blood pH magnifies Bohr effect
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18. • Temperature
- Increase in temperature depresses oxygen affinity and capacity
- Results in fish having narrow temperature tolerances.
• Organic phosphate
- ATP depresses O2 affinity
- Urea increases O2 affinity
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19. Root effect
 Root effect is defined as the oxygen carrying capacity of haemoglobin reduced at low
pH values,even at atmospheric oxygen partial pressure.
 The Root effect is a functional property of fish hemoglobins found until now only in
teleost species.
 This property consists of a drastic reduction in hemoglobin oxygen affinity, causing a
decrease in the oxygen transportation capacity when pH decreases and oxygen
tensions are high.
 The acidification that produces the Root effect is not produced by the erythrocytes
but by a special anatomical structure
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20. Root effect : Significance
 Secretion of molecular oxygen into the swim bladder
 Causes oxygen supply to the retina which does not have capillaries
 Causes the gas glands to produce lactic and carbonic acids necessary
for blood acidification
 This reduce blood capacity to transport oxygen
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21. REFERENCES
 www.bjournal.com.br
 www.scielo.br/scielo.php?.pid
 Hoar and Randall: Fish physiology
 Anthony P. Farrell; Encylopedia of fish physiology: from genome to environment 887-
895,921-925
 Evans David H;The physiology of fishes : second edition 102
 Perutz MF. Species adaptation in a protein molecule. Adv Protein Chem 1984; 36: 213-244.
 Brittain T. Root effect hemoglobins. J Inorg Biochem 2005; 99: 120129.
 Qiu Y, Maillett DH, Knapp J, Olson JS, Riggs AF. Lamprey hemoglobin. Structural basis of
the Bohr effect. J Biol Chem 2000; 275: 13517-13528
 Tsuneshige A, Park S, Yonetani T. Heterotropic effectors control the hemoglobin function by
interacting with its T and R states - a new view on the principle of allostery. Biophys Chem
2002; 98: 49-63.
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