6. PROPERTIES OF FISH HEMOGLOBINS
213
tetramers (Guidotti et al., 1963). [See Riggs (1965) and Schroeder
and Jones (1965) for review of the evidence for these conclusions.] The
number of apparent "components" which are observed after starch or
acrylamide gel electrophoresis will depend on the relationship between
the kinetics and equilibria of dissociation into subunits and the time
required for the separatory procedure. Some fish hemoglobins appear
to behave quite differently from mammalian hemoglobins in this respect.
Aggregation of tetramers (a2&, 65,000 MW 4-4.5 S ) to larger
aggregates (130,000 MW and higher, sro,," 2 6-7 S ) is of widespread
occurrence in hemolyzates of reptiles and amphibians (Svedberg and
Hedenius, 1934), but such aggregation in fish hemoglobins has only
been reported for the dogfish (Chiancone et al., 1966) and constituted
only $lo% of the total hemoglobin. Nevertheless, these polymers,
which all appear to involve intermolecular - 4 - S -
bonds, do not
appear to modify the oxygen transport function of the hemoglobin
(Riggs, 1966; Riggs and Rona, 1969) and do not involve any change
in electric charge on the molecule. Therefore, such a mutation may
not to be selected severely against. However, the almost universal occurrence in reptiles and amphibians and the almost complete absence
from fish and other vertebrates suggest that some selection is at work.
One possible function of hemoglobin -SH groups in the hemoglobins
of reptiles and amphibians might be as a reservoir of reducing power
for maintenance of the iron in the ferrous form.
2. DEVELOPMENTAL CHANGES
Ontogenetic changes in fish hemoglobin components are widespread and have been observed in three species of lamprey (Adinolfi
et aZ., 1959; Manwell, 1963b), the dogfish (Manwell, 1958a, 1963a),
the skate ( Manwell, 1958b), the teleost, Scorpaenichth yes ( Manwell,
1957), the herring and spratt (Wilkins and Iles, 1966), and four species
of salmon (Vanstone et al., 1964; Hashimoto and Matsuura, 1960b;
Koch et al., 1964, 1966; Wilkins, 1968).
The ammocoete larva of the lamprey, Petromyzon pZaneri, has two
major components which are replaced after metamorphosis with two
different components (Adinolfi et al., 1959). Since the oxy and met
forms of lamprey hemoglobin all appear to be monomeric, this finding
indicates that the two hemoglobins of the ammocoete are replaced by
two new hemoglobins, so a total of four polypeptide chains is probably involved.
Substantial evidence now exists that in a number of fish changes
in hemoglobins occur during a large fraction of the life cycle. Thus,
Wilkins and Iles (1966) have found that the youngest juveniles of the
213
tetramers (Guidotti et al., 1963). [See Riggs (1965) and Schroeder
and Jones (1965) for review of the evidence for these conclusions.] The
number of apparent "components" which are observed after starch or
acrylamide gel electrophoresis will depend on the relationship between
the kinetics and equilibria of dissociation into subunits and the time
required for the separatory procedure. Some fish hemoglobins appear
to behave quite differently from mammalian hemoglobins in this respect.
Aggregation of tetramers (a2&, 65,000 MW 4-4.5 S ) to larger
aggregates (130,000 MW and higher, sro,," 2 6-7 S ) is of widespread
occurrence in hemolyzates of reptiles and amphibians (Svedberg and
Hedenius, 1934), but such aggregation in fish hemoglobins has only
been reported for the dogfish (Chiancone et al., 1966) and constituted
only $lo% of the total hemoglobin. Nevertheless, these polymers,
which all appear to involve intermolecular - 4 - S -
bonds, do not
appear to modify the oxygen transport function of the hemoglobin
(Riggs, 1966; Riggs and Rona, 1969) and do not involve any change
in electric charge on the molecule. Therefore, such a mutation may
not to be selected severely against. However, the almost universal occurrence in reptiles and amphibians and the almost complete absence
from fish and other vertebrates suggest that some selection is at work.
One possible function of hemoglobin -SH groups in the hemoglobins
of reptiles and amphibians might be as a reservoir of reducing power
for maintenance of the iron in the ferrous form.
2. DEVELOPMENTAL CHANGES
Ontogenetic changes in fish hemoglobin components are widespread and have been observed in three species of lamprey (Adinolfi
et aZ., 1959; Manwell, 1963b), the dogfish (Manwell, 1958a, 1963a),
the skate ( Manwell, 1958b), the teleost, Scorpaenichth yes ( Manwell,
1957), the herring and spratt (Wilkins and Iles, 1966), and four species
of salmon (Vanstone et al., 1964; Hashimoto and Matsuura, 1960b;
Koch et al., 1964, 1966; Wilkins, 1968).
The ammocoete larva of the lamprey, Petromyzon pZaneri, has two
major components which are replaced after metamorphosis with two
different components (Adinolfi et al., 1959). Since the oxy and met
forms of lamprey hemoglobin all appear to be monomeric, this finding
indicates that the two hemoglobins of the ammocoete are replaced by
two new hemoglobins, so a total of four polypeptide chains is probably involved.
Substantial evidence now exists that in a number of fish changes
in hemoglobins occur during a large fraction of the life cycle. Thus,
Wilkins and Iles (1966) have found that the youngest juveniles of the