172
A. M. PERKS
its oxytocic activity, in its higher avian depressor activity, and in its lower
frog water-balance potency. Further, it had almost no effect on sodium
transport through the frog skin. Clearly, it was not oxytocin but a new
neutral principle. In the following year, Acher et al. (1962) used chromatography on Amberlite IRC-50 resin to separate the oxytocinlike principle
of Polluchius virens, Merluccius merluccius, and Gadus luscus. Analysis of
its amino acid content, together with partial enzymic degradation, suggested that the peptide was 4 Ser, 8 Ile oxytocin. Later, the same group
obtained a similar amino acid analysis for the neutral peptide of the
marine species Gadus mwrhua, Germo alulunga, and Scomber scombrus,
and for the freshwater fish, Cyprinus carpio ( Acher et al., 1965c, 1968).
The 4 Ser, 8 Ile oxytocin was synthesized by Guttman et al. (1962) and
by Johl et a2. (1963), and the product was found to be biologically similar
to oxytocin, except for its lower intrinsic pressor and antidiuretic activities; its properties were compatible with those of the teleost principle. At
the same time, W. H. Sawyer and van Dyke (1963a,b) purified the oxytocinlike principle of Pollachius virens and confirmed that its biological
activities compared well with those of synthetic 4 Ser, 8 Ile oxytocin. Similarly, W. H. Sawyer and Pickford (1963) showed that the purified neutral
principle of Fundulus heteroclitus was comparable to 4 Ser, 8 Ile oxytocin
in its chromatographic and biological characteristics. They also found that
it was preferentially lost from the pituitary of female fish during the reproductive season, while arginine vasotocin showed no seasonal changes.
In 1964, Follett and Heller (1964a) confirmed, yet again, the biological
and chromatographic similarity of synthetic 4 Ser, 8 Ile oxytocin and the
purified oxytocinlike principle of Pollachius uirens; in turn, they showed
that the pollack peptide shared many of its properties with the neutral
agents of Salmo irideus, Cyprinus sp., Anguilla anguilla, Esox hcius, and
Gadus callarias. However, the most accurate identification of the naturally
occurring 4 Ser, 8 Ile oxytocin was the complete sequence analysis
achieved in spawned-out salmon, Oncorhynchus tschawytscha, by Wilson
and Smith ( 1968; Wilson, 1968). The successful purification and analysis
of this principle was helped by the exceptionally high activities found in
these specimens, which contained a total oxytocic activity of 750-1000
mU/pituitary, as compared to values which ranged from 5 to 115 mU/
pituitary ( Gadus callarias, and Anguilla anguilla, respectively) in the
species studied by Follett and Heller ( 1964a).
In the mammals, it is well known that the neurohypophysial peptides
are associated with a special protein, neurophysin, which probably acts
as a carrier molecule within the neurohypophysis. Little is known of the
neurophysinlike carriers of the lower vertebrates, but recently Pickering
(1968) has isolated such a material from the pituitary of Gadus morrhua.
A. M. PERKS
its oxytocic activity, in its higher avian depressor activity, and in its lower
frog water-balance potency. Further, it had almost no effect on sodium
transport through the frog skin. Clearly, it was not oxytocin but a new
neutral principle. In the following year, Acher et al. (1962) used chromatography on Amberlite IRC-50 resin to separate the oxytocinlike principle
of Polluchius virens, Merluccius merluccius, and Gadus luscus. Analysis of
its amino acid content, together with partial enzymic degradation, suggested that the peptide was 4 Ser, 8 Ile oxytocin. Later, the same group
obtained a similar amino acid analysis for the neutral peptide of the
marine species Gadus mwrhua, Germo alulunga, and Scomber scombrus,
and for the freshwater fish, Cyprinus carpio ( Acher et al., 1965c, 1968).
The 4 Ser, 8 Ile oxytocin was synthesized by Guttman et al. (1962) and
by Johl et a2. (1963), and the product was found to be biologically similar
to oxytocin, except for its lower intrinsic pressor and antidiuretic activities; its properties were compatible with those of the teleost principle. At
the same time, W. H. Sawyer and van Dyke (1963a,b) purified the oxytocinlike principle of Pollachius virens and confirmed that its biological
activities compared well with those of synthetic 4 Ser, 8 Ile oxytocin. Similarly, W. H. Sawyer and Pickford (1963) showed that the purified neutral
principle of Fundulus heteroclitus was comparable to 4 Ser, 8 Ile oxytocin
in its chromatographic and biological characteristics. They also found that
it was preferentially lost from the pituitary of female fish during the reproductive season, while arginine vasotocin showed no seasonal changes.
In 1964, Follett and Heller (1964a) confirmed, yet again, the biological
and chromatographic similarity of synthetic 4 Ser, 8 Ile oxytocin and the
purified oxytocinlike principle of Pollachius uirens; in turn, they showed
that the pollack peptide shared many of its properties with the neutral
agents of Salmo irideus, Cyprinus sp., Anguilla anguilla, Esox hcius, and
Gadus callarias. However, the most accurate identification of the naturally
occurring 4 Ser, 8 Ile oxytocin was the complete sequence analysis
achieved in spawned-out salmon, Oncorhynchus tschawytscha, by Wilson
and Smith ( 1968; Wilson, 1968). The successful purification and analysis
of this principle was helped by the exceptionally high activities found in
these specimens, which contained a total oxytocic activity of 750-1000
mU/pituitary, as compared to values which ranged from 5 to 115 mU/
pituitary ( Gadus callarias, and Anguilla anguilla, respectively) in the
species studied by Follett and Heller ( 1964a).
In the mammals, it is well known that the neurohypophysial peptides
are associated with a special protein, neurophysin, which probably acts
as a carrier molecule within the neurohypophysis. Little is known of the
neurophysinlike carriers of the lower vertebrates, but recently Pickering
(1968) has isolated such a material from the pituitary of Gadus morrhua.