Toad

About: Toad is a research topic. Over the lifetime, 1624 publications have been published within this topic receiving 28732 citations.

Effect of lithium chloride on spermatogenesis, testicular delta 5- 3 beta- and 17 beta-hydroxysteroid dehydrogenase activities in toad (Bufo melanostictus)

Abstract: The purpose of the present study was to show the effects of lithium on testicular activities in the toad. Adult male toads were injected with lithium chloride (200 micrograms/toad) of alternate days for 21 days. At the moment of sacrifice on 22nd day, lithium treated animal showed decreases in testicular weight and Leydig cell nuclear area along with inhibition of spermatogenesis and testicular delta 5-3 beta as well as 17 beta-hydroxysteroid dehydrogenase activities. The results of our present experiment suggest that lithium administration might be associated with significant adverse effects on testicular activity in toad.

The sympathetic innervation of the skin of the toad.

Abstract: THE general scheme of sympathetic innervation in the frog has been determined by Langley and Orbeli(i) on the basis of the visceromotor fibres and by Langley(2) on that of the vaso-motor fibres. In the toad it was investigated by Langley and Orbeli(3) by the degeneration method. They concluded that the scheme in broad features was the same as that shown by Langley in the mammal and bird. E. J. BrUcke(4) in recent experiments on the innervation of the skin glands of the toad describes results which do not harmonise with this conclusion. According to him, sympathetic secretory fibres occur in the roots of the spinal nerves giving origin to the pelvic nerve, and in consequence he suggests that the sacral autonomic nerves of Langley and Orbeli are of sympathetic origin. Moreover he found relatively little overlapping in the areas of the skin of the trunk supplied by the successive spinal nerves and a much less extensive origin of the secretory fibres supplying the hind limb than that given by Langley of the vaso-constrictor fibres. In view of these experiments, I have, at Prof. Langley's suggestion, re-investigated the origin of the sympathetic fibres supplying the skin glands of the toad. Method. The toads weighed about 25 to 50 grms.; 0-2 to 0 5 c.c. of 25 p.c. urethane was injected subcutaneously into the dorsal lymph sac. This dose, which was about half that used by Briicke, was given since it was found in general that a larger one decreased the amount of secretion obtained. The cerebral hemispheres and a part of the midbrain were destroyed and the spinal cord exposed. The dura mater was cut through, the 8th to the 10thl posterior roots of both sides and the cauda equina were tied separately and cut peripherally of the ligatures. Lifting the ligatures all the remaining spinal roots, both anterior and posterior, were cut at the nearest point to the cord and the spinal cord was removed. The roots floating in the blood and cerebro-spinal fluid were lifted with a fine hooked probe, placed on the edge of the spinal canal and tied with thin silk. The fine anterior and posterior roots of the 3rd to the 6th nerves were generally tied and stimulated together.

Characterization of a novel receptor in toad retina with dual specificity for insulin and insulin-like growth factor I.

Abstract: The biochemical properties of insulin receptors from toad retinal membranes were examined in an effort to gain insight into the role this receptor plays in the retina. Competition binding assays revealed that toad retinal membranes contained binding sites that displayed an equal affinity for insulin and insulin-like growth factor I (IGF-I). Affinity labeling of toad retinal membrane proteins with 125I-insulin resulted in the specific labeling of insulin receptor alpha-subunits of approximately 105 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of partially reduced (alpha beta-heterodimer) receptors affinity-labeled with 125I-insulin indicated the presence of a disulfide-linked beta-subunit of approximately 95 kDa. Endoglycosidase F digestion of the affinity-labeled alpha-subunits increased their mobility by reducing their apparent mass to approximately 83 kDa. This receptor was not detected by immunoblot analysis with a site-specific antipeptide antibody directed against residues 657-670 of the carboxy terminal of the human insulin receptor alpha-subunit, whereas this antibody did label insulin receptor alpha-subunits from pig, cow, rabbit, and chick retinas. In in vitro autophosphorylation assays insulin stimulated the tyrosine phosphorylation of toad retina insulin receptor beta-subunits. These data indicate that toad retinal insulin receptors have a heterotetrameric structure whose alpha-subunits are smaller than other previously reported neuronal insulin receptors. They further suggest that a single receptor may account for both the insulin and IGF-I binding activities associated with toad retinal membranes.

The parotoid gland of the toad, bufo americanus

Abstract: A histological study of the poison glands of the toad demonstrated that one of the components of their secretion is adrenalin or adrenalin precursor substances. The poison glands are arranged in ag...