248
AUBREY GORBMAN
annual pituitary cycle of TSH concentration in temperate zone species
(e.g., the cod: Woodhead and Fontaine, 1959; perch: Swift and Pickford,
1965; catfish: Singh, 1967). It would seem that such cycles must be under
hypothalamic control since they depend eventually upon sensory afferent
information.
The properties and chemical characteristics of teleostean TSH have
been a continuing interest of Y. A. Fontaine (1955) and have been the
subject of a number of publications from his laboratory. Y. A. Fontaine
and Condliffe (1963) purified TSH of the eel to a high level of specific
activity, 15 “units” per milligram, and this as well as similar purified hormone has served for further work. A part of such further study has been
concerned with the degree of molecular differentiation or evolution that
has occurred during vertebrate evolution (M. Fontaine and Fontaine,
1962; Y. A. Fontaine, 1958, 1967). Gorbman (1946, 1959) showed earlier
that the chemical variation in TSHs is sufficiently great that it can be
revealed in physiological tests by reciprocal bioassay. That is, if crude
pituitary preparations from a series of vertebrates are tested for their
thyrotropic potency according to their effects on thyroids of a series of
vertebrates, the tendency is for greater potency in recipient species most
closely related ( phylogenetically ) to the animal source of the pituitary.
Y. A. Fontaine and Dellerue-Lebelle (1967) have employed immunological techniques to reveal some of these relationships in a different way.
They found, for example, that the mouse thyroid can be stimulated by
beef or mouse TSH, but not by that from teleost pituitary. Lungfish
TSH will stimulate mouse thyroid in the doses used. Anti-beef TSH antibody will neutralize mouse TSH but not that of teleosts or lungfish. Thus,
the molecular differences between mouse, lungfish, and teleost TSH appear to be such that lungfish is intermediate between the other two,
distinguishable by immunological properties from the mammal, but not
clearly differentiated by bioassay.
In the converse sense, it would seem that the fish thyroid is more
responsive to mammalian TSH, than mammalian thyroid to fish TSH. For
example, goldfish thyroid is sufficiently responsive to mammalian TSH to
permit use of -these fish for bioassay ( Gorbman, 1940; Ortman and Billig,
1966). Mammalian thyroids clearly are not as suitable for bioassay of
teleostean TSH, although some slight responsiveness can be shown
(Leloup and Fontaine, 1956).
One reason for the apparently greater responsiveness to various pituitary preparations by the fish thyroid than by the mammalian thyroid is
that fish thyroid may not discriminate closely among pituitary hormones.
Y. A. Fontaine has found, for example, that a substance in mammalian
pituitary preparations other thaa TSH will stimulate the teleost thyroid
AUBREY GORBMAN
annual pituitary cycle of TSH concentration in temperate zone species
(e.g., the cod: Woodhead and Fontaine, 1959; perch: Swift and Pickford,
1965; catfish: Singh, 1967). It would seem that such cycles must be under
hypothalamic control since they depend eventually upon sensory afferent
information.
The properties and chemical characteristics of teleostean TSH have
been a continuing interest of Y. A. Fontaine (1955) and have been the
subject of a number of publications from his laboratory. Y. A. Fontaine
and Condliffe (1963) purified TSH of the eel to a high level of specific
activity, 15 “units” per milligram, and this as well as similar purified hormone has served for further work. A part of such further study has been
concerned with the degree of molecular differentiation or evolution that
has occurred during vertebrate evolution (M. Fontaine and Fontaine,
1962; Y. A. Fontaine, 1958, 1967). Gorbman (1946, 1959) showed earlier
that the chemical variation in TSHs is sufficiently great that it can be
revealed in physiological tests by reciprocal bioassay. That is, if crude
pituitary preparations from a series of vertebrates are tested for their
thyrotropic potency according to their effects on thyroids of a series of
vertebrates, the tendency is for greater potency in recipient species most
closely related ( phylogenetically ) to the animal source of the pituitary.
Y. A. Fontaine and Dellerue-Lebelle (1967) have employed immunological techniques to reveal some of these relationships in a different way.
They found, for example, that the mouse thyroid can be stimulated by
beef or mouse TSH, but not by that from teleost pituitary. Lungfish
TSH will stimulate mouse thyroid in the doses used. Anti-beef TSH antibody will neutralize mouse TSH but not that of teleosts or lungfish. Thus,
the molecular differences between mouse, lungfish, and teleost TSH appear to be such that lungfish is intermediate between the other two,
distinguishable by immunological properties from the mammal, but not
clearly differentiated by bioassay.
In the converse sense, it would seem that the fish thyroid is more
responsive to mammalian TSH, than mammalian thyroid to fish TSH. For
example, goldfish thyroid is sufficiently responsive to mammalian TSH to
permit use of -these fish for bioassay ( Gorbman, 1940; Ortman and Billig,
1966). Mammalian thyroids clearly are not as suitable for bioassay of
teleostean TSH, although some slight responsiveness can be shown
(Leloup and Fontaine, 1956).
One reason for the apparently greater responsiveness to various pituitary preparations by the fish thyroid than by the mammalian thyroid is
that fish thyroid may not discriminate closely among pituitary hormones.
Y. A. Fontaine has found, for example, that a substance in mammalian
pituitary preparations other thaa TSH will stimulate the teleost thyroid