2. THE NEUROHYPOPHYSIS
171
which had been known only as a synthetic material up to that time
(Katsoyannis and du Vigneaud, 1958, 1959). This observation was extended by Chauvet et al. (19Sl), who used chromatography on Amberlite
IRC-50 resin to separate two active peptides from the pituitaries of
Merluccius merluccius. Although the first principle to elute had mainly
oxytocic activity, the second principle showed frog bladder, vasopressor,
and natriferic activities which were consistent, once again, with the presence of arginine vasotocin. A similar separation was achieved for Polluchius virenr by Heller and Pickering (1960, 1961); they used column
chromatography on Amberlite CG-50 and obtained a frog water-balance
and pressor principle which could not be distinguished from arginine
vasotocin, either by chromatography or by biological assays. More important, they obtained a tentative analysis of its amino acid composition
and found a general agreement with those amino acids present in arginine
vasotocin. This result was extended by Rassmussen and Craig ( 1961);
these workers used countercurrent distribution methods to purify the frog
water-balance principle of Urophycis tenuis (incorrectly identified as
Merluccius vulgaris; Sawyer and Pickford, 1963). They obtained a more
precise analysis of the purified principle and showed that it contained
the same amino acids as arginine vasotocin. They also noted that there
was a general agreement between the biological potencies of their purified product and those of synthetic arginine vasotocin. Since this time,
similar amino acid analyses have been obtained for Gadus luscus, G. morrhua, G e m alulunga, Scomber scombrus, and for the freshwater species,
Cyprinus carpi0 (Acher et al., 1961, 1965c, 1968). Recently, Wilson and
Smith (1968; Wilson, 1968) have achieved a complete sequence analysis
of the frog water-balance factor of spawning salmon, Oncmhynchus
tschawytschu, and its identity with arginine vasotocin has been clearly
established.
During the early investigations, which concentrated on arginine vasotocin, the presence of an oxytocinlike peptide had been indicated in four
species by pharmacological or chromatographic means ( Salmo sp., Gadus
sp., Pickering and Heller, 1959; Gadus luscus, Acher et al., 1961; Pollachius
virens, Pickering and Heller, 1959; Heller and Pickering, 1961; W. H.
Sawyer et al., 1959, 1961; Merluccim merluccius, Chauvet et al., 1961).
At first it was assumed that this principle was oxytocin itself since its
chromatographic behavior and its general spectrum of biological activities seemed similar to those of the mammalian principle (Pickering and
Heller, 1959; W. H. Sawyer et al., 1961). However, in 1961, Heller et al.
made a careful comparison of the two peptides and showed that the oxytocinlike principle of Pollachius virens differed from oxytocin in relatively
small, but significant, ways. It differed in the magnesium potentiation of
171
which had been known only as a synthetic material up to that time
(Katsoyannis and du Vigneaud, 1958, 1959). This observation was extended by Chauvet et al. (19Sl), who used chromatography on Amberlite
IRC-50 resin to separate two active peptides from the pituitaries of
Merluccius merluccius. Although the first principle to elute had mainly
oxytocic activity, the second principle showed frog bladder, vasopressor,
and natriferic activities which were consistent, once again, with the presence of arginine vasotocin. A similar separation was achieved for Polluchius virenr by Heller and Pickering (1960, 1961); they used column
chromatography on Amberlite CG-50 and obtained a frog water-balance
and pressor principle which could not be distinguished from arginine
vasotocin, either by chromatography or by biological assays. More important, they obtained a tentative analysis of its amino acid composition
and found a general agreement with those amino acids present in arginine
vasotocin. This result was extended by Rassmussen and Craig ( 1961);
these workers used countercurrent distribution methods to purify the frog
water-balance principle of Urophycis tenuis (incorrectly identified as
Merluccius vulgaris; Sawyer and Pickford, 1963). They obtained a more
precise analysis of the purified principle and showed that it contained
the same amino acids as arginine vasotocin. They also noted that there
was a general agreement between the biological potencies of their purified product and those of synthetic arginine vasotocin. Since this time,
similar amino acid analyses have been obtained for Gadus luscus, G. morrhua, G e m alulunga, Scomber scombrus, and for the freshwater species,
Cyprinus carpi0 (Acher et al., 1961, 1965c, 1968). Recently, Wilson and
Smith (1968; Wilson, 1968) have achieved a complete sequence analysis
of the frog water-balance factor of spawning salmon, Oncmhynchus
tschawytschu, and its identity with arginine vasotocin has been clearly
established.
During the early investigations, which concentrated on arginine vasotocin, the presence of an oxytocinlike peptide had been indicated in four
species by pharmacological or chromatographic means ( Salmo sp., Gadus
sp., Pickering and Heller, 1959; Gadus luscus, Acher et al., 1961; Pollachius
virens, Pickering and Heller, 1959; Heller and Pickering, 1961; W. H.
Sawyer et al., 1959, 1961; Merluccim merluccius, Chauvet et al., 1961).
At first it was assumed that this principle was oxytocin itself since its
chromatographic behavior and its general spectrum of biological activities seemed similar to those of the mammalian principle (Pickering and
Heller, 1959; W. H. Sawyer et al., 1961). However, in 1961, Heller et al.
made a careful comparison of the two peptides and showed that the oxytocinlike principle of Pollachius virens differed from oxytocin in relatively
small, but significant, ways. It differed in the magnesium potentiation of