5. THE ENDOCRINE PANCREAS
289
However, recent investigations (cf. S. Wilson, 1966; Falkmer and Wilson,
1967) make it clear that there are considerable differences in both biological and immunological properties not only between mammalian and
teleost insulins but also among teleost insulins. The blood glucose of
teleosts appears markedly resistent to both teleost and bovine preparations (Falkmer, 1961; Tashima and Cahill, 1964; Falkmer and Wilson,
1967). Also, antisera of ox insulin failed to provoke hyperglycemia in
Cottus scorpius. Even homologous insulin of this species is surprisingly
ineffective (Falkmer and Wilson, 1967). On the other hand, Young and
Chavin (1967) reported a hypoglycemic effect of low doses of bovine,
bonito, tuna, Hydrolugus, and Squalus insulins in the goldfish, Carassius
auratus.
Insulin from Opsanus tau influenced glucose uptake in rat adipose
tissue but not in the muscle (Cahill et al., 1964). On the other hand,
mammalian insulin had no effect on the incorporation of glu~ose-U-~~C
into lipids, fatty acids, glycogen, or CO, of tissue preparations (heart,
liver, and skeletal muscle) of Opsanus tau (Tashima and Cahill, 1964).
Certainly, the differing biological and immunological properties of the
insulins result from differences in the molecular structures (6. Wilson,
1966; Smith, 1966; Eck and Dayhoff, 1966; P. T. Grant and Reid, 1968).
A proportion of the primary structure of all insulins studied so far is invariable. However, the common amino acid sequences of the B chains of
tetrapod and teleost insulins are only discernible when the whole sequence of the teleost B chain is advanced one position toward the Nterminal (Eck and Dayhoff, 1966; P. T. Grant and Reid, 1968). Nevertheless, phylogenetic conclusions from the biological effects of insulins
in the teleosts would be premature because a variety of environmental
factors may have a strong influence on the reactions to exogenous insulin
(see Section IV, C, 1 ) .
While the rat (Smith, 1966) is the only mammal known to have two
forms of insulin (which only differ in position 29 of the B chain), several
teleosts have been shown to produce two different insulins: the bonito,
Katsuwonus pelurnis ( ?) (Kotaki, 1963), the flounder, Pleuromctes flesus
(Jorgensen, 1960), and the goosefish, Opsanua tau (Smith, 1966). The
differences in both biological activity and molecular structure between
the insulins of codfish, Gadus callarim, from North American ( S . Wilson
and Dixon, 1961 ) and European waters (P. T. Grant and Reid, 1968) can
possibly be explained by racial variations.
In conclusion, the differences in structure and in both biological and
immunological properties between the insulin of M y x i w and gnathostome
insulins appear to be greater than the differences among the heretofore
known gnathostome insulins. On the other hand, the teleost insulins
289
However, recent investigations (cf. S. Wilson, 1966; Falkmer and Wilson,
1967) make it clear that there are considerable differences in both biological and immunological properties not only between mammalian and
teleost insulins but also among teleost insulins. The blood glucose of
teleosts appears markedly resistent to both teleost and bovine preparations (Falkmer, 1961; Tashima and Cahill, 1964; Falkmer and Wilson,
1967). Also, antisera of ox insulin failed to provoke hyperglycemia in
Cottus scorpius. Even homologous insulin of this species is surprisingly
ineffective (Falkmer and Wilson, 1967). On the other hand, Young and
Chavin (1967) reported a hypoglycemic effect of low doses of bovine,
bonito, tuna, Hydrolugus, and Squalus insulins in the goldfish, Carassius
auratus.
Insulin from Opsanus tau influenced glucose uptake in rat adipose
tissue but not in the muscle (Cahill et al., 1964). On the other hand,
mammalian insulin had no effect on the incorporation of glu~ose-U-~~C
into lipids, fatty acids, glycogen, or CO, of tissue preparations (heart,
liver, and skeletal muscle) of Opsanus tau (Tashima and Cahill, 1964).
Certainly, the differing biological and immunological properties of the
insulins result from differences in the molecular structures (6. Wilson,
1966; Smith, 1966; Eck and Dayhoff, 1966; P. T. Grant and Reid, 1968).
A proportion of the primary structure of all insulins studied so far is invariable. However, the common amino acid sequences of the B chains of
tetrapod and teleost insulins are only discernible when the whole sequence of the teleost B chain is advanced one position toward the Nterminal (Eck and Dayhoff, 1966; P. T. Grant and Reid, 1968). Nevertheless, phylogenetic conclusions from the biological effects of insulins
in the teleosts would be premature because a variety of environmental
factors may have a strong influence on the reactions to exogenous insulin
(see Section IV, C, 1 ) .
While the rat (Smith, 1966) is the only mammal known to have two
forms of insulin (which only differ in position 29 of the B chain), several
teleosts have been shown to produce two different insulins: the bonito,
Katsuwonus pelurnis ( ?) (Kotaki, 1963), the flounder, Pleuromctes flesus
(Jorgensen, 1960), and the goosefish, Opsanua tau (Smith, 1966). The
differences in both biological activity and molecular structure between
the insulins of codfish, Gadus callarim, from North American ( S . Wilson
and Dixon, 1961 ) and European waters (P. T. Grant and Reid, 1968) can
possibly be explained by racial variations.
In conclusion, the differences in structure and in both biological and
immunological properties between the insulin of M y x i w and gnathostome
insulins appear to be greater than the differences among the heretofore
known gnathostome insulins. On the other hand, the teleost insulins