Temperature-dependent intracellular distribution of thyroxine in amphibian liver.
نویسندگان
چکیده
Rana catesbeiana tadpoles were injected with [(14)C]thyroxine, and the subcellular distribution of the labeled hormone was determined. At 25 degrees the amount of isotope found in the liver was maximal after 1-2 hr and then rapidly decreased to a relatively constant value. A large percentage of the hormone was found associated with the purified nuclei isolated 24 hr after injection of [(14)C]thyroxine. Injection of [(14)C]thyroxine into tadpoles maintained at 5 degrees resulted in a much slower but constant accumulation of isotope in the liver, with virtually no movement of thyroxine into the cell nucleus. Thyroxine was bound very tightly to the chromatin fraction of the nucleus, but extraction and chromatography revealed no chemical modification of the thyroxine itself. These results suggest the presence of two temperature-dependent processes: one concerned with the transport of thyroxine into the liver cell and a second concerned with the transport of the intracellular thyroxine into the cell nucleus. It is proposed that the latter process is involved in the low-temperature inhibition of thyroxine-induced metamorphosis.
منابع مشابه
Biochemical Studies on Amphibian Metamorphosis I. The effect of thyroxine on protein synthesis in the tadpole
Thyroxine has been shown to accelerate the synthesis of carbamyl phosphate synthetase in the liver of Rana catesbdana. Stimulation of carbamyl phosphate synthetase synthesis by thyroxine appears to be relatively specific because of the following observations: (I) succinoxidase activity decreased during the time that carbamyl phosphate synthetase increased; (2) liver catalase responded more slow...
متن کاملBiochemical Studies on Amphibian Metamorphosis I. The effect of thyroxine on protein synthesis in the tadpole
Thyroxine has been shown to accelerate the synthesis of carbamyl phosphate synthetase in the liver of Rana catesbdana. Stimulation of carbamyl phosphate synthetase synthesis by thyroxine appears to be relatively specific because of the following observations: (I) succinoxidase activity decreased during the time that carbamyl phosphate synthetase increased; (2) liver catalase responded more slow...
متن کاملBiochemical Studies on Amphibian Metamorphosis
Thyroxine has been shown to accelerate the synthesis of carbamyl phosphate synthetase in the liver of Rana catesbeiana. Stimulation of carbamyl phosphate synthetase synthesis by thyroxine appears to be relatively specific because of the following observations: (1) succinoxidase activity decreased during the time that carbamyl phosphate synthetase increased; (2) liver catalase responded more slo...
متن کاملEffects of developmental and growth history on metamorphosis in the gray treefrog, Hyla versicolor (Amphibia, Anura).
In ecological models, the timing of amphibian metamorphosis is dependent upon rate of larval growth, e.g., tadpoles that experience a decrease in growth rate can initiate metamorphosis early. Recent authors have suggested that this plasticity may be lost at some point during the larval period. We tested this hypothesis by exposing groups of tadpoles of the gray treefrog, Hyla versicolor, to dif...
متن کاملThe Swelling of Rat Liver Mitochondria by Thyroxine and its Reversal
The in vitro swelling action of L-thyroxine on rat liver mitochondria as examined photometrically represents an acceleration of a process which the mitochondria are already inherently capable of undergoing spontaneously, as indicated by the identical kinetic characteristics and the extent of thyroxine-induced and spontaneous swelling, the nearly identical pH dependence, and the fact that sucros...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 69 6 شماره
صفحات -
تاریخ انتشار 1972