4. THYROID FUNCTION AND ITS CONTROL IN FISHES
253
analysis of iodine metabolism is a project for the chemical laboratory, and
the fishes most frequently stocked in or near the laboratory are most
readily studied. However, despite this, a sufficient variety of piscine species has been studied to permit some generalization (Table 1 in Berg
et al., 1959), and an excellent and detailed study was made by Hickman
(1962) on a flounder, Platichthys stellatus. Thyroid function in the European eel, Anguilla anguilla, has been a continuing subject for study in
Fontaine's laboratory, particularly with colleagues Leloup and Olivereau
( cited on pages 255,258, and 259).
Apparently the small freshwater platyfish, Xiphophorus maculatm,
was the first teleost whose thyroidal utilization of radioiodine was studied
by chromatographic methods (Berg and Gorbman, 1953). Qualitatively,
it was typical in showing an eventual synthesis of thyroxine. However,
new thyroxine synthesis, up to 6 days after injection of tracer 1311 was
never very high in proportion. Since this work many similar experiments
have been conducted with generally similar results but with some
interesting differences.
In a purely quantitative sense, there are great differences in the avidity
of the thyroids of various species of fish for administered iodine (as revealed by uptake of carrier-free radioiodine) (Fig. 3), as well as in the
rate of loss of organically bound iodine from the thyroid gland. As Hick1
I
I
I
I
1
Time in hours
Fig. 3. Thyroidal radioiodine uptake and loss of 1311 over a period of time in seven
species of freshwater teleosts maintained at 21OC. ( 1 ) Carassius auratus in tap water
in July. ( 2 ) Lepomis gibbosus in tap water in August. ( 3 ) Percina caprodes in native
lake water in June. ( 4 ) Notropis deliciosus in native lake water in July. ( 5 ) Umbra
limi in tap water in March. ( 6 ) Umbra pygmaeus in tap water in June. ( 7 ) Xiphophorus maculatus in aquarium conditioned water throughout the year. From Berg
et al. (1959).
253
analysis of iodine metabolism is a project for the chemical laboratory, and
the fishes most frequently stocked in or near the laboratory are most
readily studied. However, despite this, a sufficient variety of piscine species has been studied to permit some generalization (Table 1 in Berg
et al., 1959), and an excellent and detailed study was made by Hickman
(1962) on a flounder, Platichthys stellatus. Thyroid function in the European eel, Anguilla anguilla, has been a continuing subject for study in
Fontaine's laboratory, particularly with colleagues Leloup and Olivereau
( cited on pages 255,258, and 259).
Apparently the small freshwater platyfish, Xiphophorus maculatm,
was the first teleost whose thyroidal utilization of radioiodine was studied
by chromatographic methods (Berg and Gorbman, 1953). Qualitatively,
it was typical in showing an eventual synthesis of thyroxine. However,
new thyroxine synthesis, up to 6 days after injection of tracer 1311 was
never very high in proportion. Since this work many similar experiments
have been conducted with generally similar results but with some
interesting differences.
In a purely quantitative sense, there are great differences in the avidity
of the thyroids of various species of fish for administered iodine (as revealed by uptake of carrier-free radioiodine) (Fig. 3), as well as in the
rate of loss of organically bound iodine from the thyroid gland. As Hick1
I
I
I
I
1
Time in hours
Fig. 3. Thyroidal radioiodine uptake and loss of 1311 over a period of time in seven
species of freshwater teleosts maintained at 21OC. ( 1 ) Carassius auratus in tap water
in July. ( 2 ) Lepomis gibbosus in tap water in August. ( 3 ) Percina caprodes in native
lake water in June. ( 4 ) Notropis deliciosus in native lake water in July. ( 5 ) Umbra
limi in tap water in March. ( 6 ) Umbra pygmaeus in tap water in June. ( 7 ) Xiphophorus maculatus in aquarium conditioned water throughout the year. From Berg
et al. (1959).