Fish hemoglobins

Abstract

Vertebrate hemoglobin, contained in erythrocytes, is a globular protein with a quaternary structure composed of 4 globin chains (2 alpha and 2 beta) and a prosthetic group named heme bound to each one. Having myoglobin as an ancestor, hemoglobin acquired the capacity to respond to chemical stimuli that modulate its function according to tissue requirements for oxygen. Fish are generally submitted to spatial and temporal O 2 variations and have developed anatomical, physiological and biochemical strategies to adapt to the changing environmental gas availability. Structurally, most fish hemoglobins are tetrameric; however, those from some species such as lamprey and hagfish dissociate, being monomeric when oxygenated and oligomeric when deoxygenated. Fish blood frequently possesses several hemoglobins; the primary origin of this finding lies in the polymorphism that occurs in the globin loci, an aspect that may occasionally confer advantages to its carriers or even be a harmless evolutionary remnant. On the other hand, the functional properties exhibit different behaviors, ranging from a total absence of responses to allosteric regulation to drastic ones, such as the Root effect.

Erythrocytes in teleost fishes: a review

“…salmonids) have hemoglobins of lower oxygen affinity (Nikinmaa 2001). The presence of multiple hemoglobin isoforms of different oxygen binding affinity was observed in some fish species (De Souza and Bonilla-Rodriguez 2007). According to Nikinmaa (2001), a shift in the proportion of various hemoglobins showing different oxygen affinity is one of possible ways of adaptation of fish to variable dissolved oxygen levels.…”

“…The main factor decreasing affinity is the influence of protons -the Bohr effect and a similar effect of CO 2 . The Bohr effect facilitates release of oxygen at the tissue level under conditions of increased metabolic demand indicated by metabolic acidosis (De Souza and Bonilla-Rodriguez 2007). Another effect of low pH on hemoglobin oxygen affinity -the Root effect occurs essentially in some teleost fishes, and describes the fact that hemoglobin cannot be fully saturated with oxygen (Kunzmann 1991).…”

“…Another effect of low pH on hemoglobin oxygen affinity -the Root effect occurs essentially in some teleost fishes, and describes the fact that hemoglobin cannot be fully saturated with oxygen (Kunzmann 1991). According to De Souza and Bonilla-Rodriguez (2007), the Root effect is necessary to fill the swim bladder and to supply oxygen to retina which lacks capillaries.…”

Biochemical Characterization of Hemoglobins from Caspian Sea Sturgeons (Acipenser persicus and Acipenser stellatus)

“…All Sturgeon species are members of the order Acipenseriformes that have a special place in historical ideas about the classification and evolution of fishes [52]. Concerning the evolutionary profile of Acipensers as living fossils, the emergence of these fishes goes back to the Triassic period from Condrostei superorder [53,54]. Their exceptionally slow evolution can be explained by various reasons.…”

Uji Toksisitas Letal dan Subletal Logam Berat Merkuri (Hg) Terhadap Ikan Nilem (Osteochilus hasselti)

“…Hemoglobin yang berfungsi sebagai transpor O 2 dan CO 2 menjadi terhambat, dan naik atau turunnya kadar hemoglobin akan diikuti oleh angka hematokrit (Souza dan Rodriguez, 2007 …”