Toad

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

Sexual dimorphism in succinic dehydrogenase staining of toad pretrigeminal nucleus.

Abstract: The anuran (toad and frog) pretrigeminal nucleus is probably involved in the production of vocalizations, including the male mating call. This nucleus is especially obvious when stained by the succinic dehydrogenase method. In the American toad, a striking sexual dimorphism is shown by such staining. The male nucleus contains numerous, large cells that stain intensely. Such cells are smaller and infrequent in females.

Myosin heavy chain isoform expression and Ca2 +-stimulated ATPase activity in single fibres of toad rectus abdominis muscle.

Abstract: Segments of single fibres from the rectus abdominis (RA) muscles of adult and juvenile cane toads (Bufo marinus) were examined for myosin heavy chain (mHC) isoform expression and Ca2+-stimulated MgATPase activity. mHC isoform analyses were carried out using the recently developed alanine–SDS–PAGE method, which separates one tonic (BmHCT) and three twitch (BmHC1, BmHC2, BmHC3) mHC isoforms in toad skeletal muscle. Ca2+-stimulated MgATPase activity was measured by spectrophotometric determination of Pi, under conditions in which the ATPase associated with the sarcoplasmic reticulum (SR ATPase) was suppressed by feedback inhibition. The mHC-based fibre types identified in this study include three pure twitch fibre types (t1, t2 and t3), expressing BmHC1, BmHC2 or BmHC3 respectively, and seven hybrid fibre types co-expressing a combination of two or three twitch and tonic or twitch and twitch mHC isoforms. The fibre populations dissected from juvenile and adult toad muscles contained 49.4% (juvenile) and 73.7% (adult) mHC hybrids. The average values for Ca2+-stimulated MgATPase in pure twitch fibres and in fibres expressing predominantly (≥95%) the tonic mHC isoform (T p fibres) differed significantly (P t2 > t3 > T p. We conclude that (i) in RA muscles of both juvenile and adult cane toads there is a large proportion of mHC hybrids, some of which co-express twitch and tonic mHC isoforms and (ii) ATPase activities associated with the four mHC isoforms expressed in toad skeletal muscles decrease in the order BmHC1 > BmHC2 > BmHC3 > BmHCT.

Electrolyte sensitivity of the skin in the toad, Bufo arenarum Hensel.

Abstract: Experiments on the responsiveness of the skin to solutions of different electrolytes and sucrose have been done in the toad in vivo and in vitro. Brain pithed animals showed a strong flexor "on" response of the hindlimb when the foot was plunged into a saline solution. The delay of this response was strictly proportional to the concentration of the bath from 0.5 to 1 M. The flexor response was invariably elicited by solutions of different salts: NaCl, KCl, Na2SO4, CaCl, MgSO4 and choline chloride, but not by a solution of sucrose with the same osmolarity. On the other hand, a contrast "off" response with strong flexion was also systematically observed when a limb adapted to electrolyte solution was displaced to distilled water. Patches of skin were also exposed to increasing concentrations of NaCl in vitro and the discharges of its afferent nerve were recorded. A clear cut correlation between the osmolarity of the bath and the rate of discharges was observed. The contrast "off" response to distilled water after exposure to NaCl was also observed in the patches of skin, as an increase in nervous discharges. The spontaneous basal firing observed in water, as well as the induced responses by electrolytes, were reversibly blocked by decreasing the temperature of the bath to 0 C. These results indicate that detectors of salinity are present in the skin of the toad. These detectors appear to be sensitive to the ionization but not to the osmolarity of the bath.

Genome size in the green toad (Bufo viridis) group

Abstract: Specimens of the green toad,Bufo viridis, from Morocco to Kirgizistan, have identical DNA amounts per erythrocyte nucleus. 1 specimen from Kirgizistan is a tetraploid. Of 3 closely related species,B. calamita andB. brongersmai have about the same DNA amount asB. viridis, whileB. latastii from Afghanistan has 36% more DNA per nucleus.