Toad

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

Effects of temperature on contractile properties of skinned muscle fibers from three toad species

Abstract: Single fast fibers were isolated from the iliofibularis muscles of three species of toad with different thermal minima for active locomotion: 8 degrees C, American toad, Bufo americanus; 15 degrees C, Rocky Mountain toad, Bufo woodhousei woodhousei; 22 degrees C, Cane toad, Bufo marinus. All experiments were carried out during the summer. Fibers were chemically skinned and maximum isometric tension and unloaded contraction velocity were determined at a series of temperatures between 0 and 35 degrees C. At 25-30 degrees C, isometric tension development has a low temperature dependence (R10 = 1.1-1.3) and is in the range of 210-260 kN X m-2 for each of the three toads. However, at 0-10 degrees C, absolute values of tension increase in the series (B. americanus greater than B. woodhousei greater than B. marinus; i.e., with increasing cold tolerance), while thermal sensitivity between 0 and 10 degrees C is inversely related to cold tolerance. For example, at 0 degree C, maximum isometric tension (Po) for the most northerly distributed species is three times higher than for the subtropical to tropical species (P less than 0.001). R10 for Po (0-10 degrees C) is 1.7 for B. marinus, 1.3 for B. w. woodhousei, and 1.0 for B. americanus. In contrast, unloaded shortening speeds were similar at any given temperature for the three species. It is concluded that adaptations in Bufo myosin for activity at low temperatures largely involves changes in force production.

Galanin-like immunoreactive expression in the central nervous system of the toad.

Abstract: The distribution of galanin (GAL)-like immunoreactivity (-LI) was studied in the CNS of the toad (Bufo arenarum Hensel). Tissue sections were incubated with antibodies directed toward rat or porcine GAL and processed either for the avidin-biotin complex, or for the indirect immunofluorescence techniques. In the telencephalon GAL-immunoreactive (-IR) perikarya were observed in the ventral part of the striatum and in the septal accumbens nuclei. Immunopositive neurons were also observed in the medial amigdala with some intermingled cells between the fibers of the anterior commissure. Numerous GAL-IR perikarya were present along the rostrocaudal medial preoptic nucleus. Occasionally lightly immunoreactive cells were detected in the magnocellular region. The most numerous accumulation of GAL-IR cells was present in the ventral hypothalamus around the infundibular region, in the posterior tubercle and in the nucleus of the paraventricular organ. Immunostained cells were also present in the pretectal gray, solitary nucleus, gracil nucleus and in the spinal cord in the intermediate gray and in large motoneurons of the ventral horn. The widespread distribution found of GAL-LI suggests that GAL in the toad, as well as in mammalian species, may serve a variety of functions with a preponderant role in neuroendocrine processes. A role for GAL as a trophic factor in the brain of the toad is also suggested.

Immunochemical investigations on toad (Bufo) eggs: comparative studies on three species (B. bufo, B. viridis, B. calamita).

Abstract: Eggs of three Bufo species (B. bufo, B. viridis and B. calamita) were examined for blood group activity. B. bufo showed distinct A activity, whereas in B. viridis and B. calamita a marked H-activity was observed. These results correspond with the zoological systematic classification of the three toad species tested.