Showing papers on "Toad published in 2007"

Life-threatening episode after ingestion of toad eggs: a case report with literature review.

Abstract: It is known that toad possesses several toxic substances in the skin and parotid glands. In the past, toad‐venom poisoning had been reported from ingestion of toad soup, Kyushin and aphrodisiac pills, but the poisoning from toad eggs is observed for the first time. The case of a healthy female who had previously eaten toad soup twice without any discomfort is reported. She developed gastrointestinal symptoms and life‐threatening cardiac rhythm after ingestion of toad eggs.

Immunolocalization and mRNA expression of the epithelial Na+ channel α-subunit in the kidney and urinary bladder of the marine toad, Bufo marinus, under hyperosmotic conditions

Abstract: The amiloride-sensitive epithelial sodium channel (ENaC) has previously been shown to be involved in the maintenance of body fluid volume and in Na+ absorption across the skin and urinary bladder in amphibians. However, the function and distribution of ENaC have not been clearly described in amphibian kidney. We therefore cloned the ENaC α-subunit cDNA from kidney of the marine toad, Bufo marinus. The ENaC mRNA and protein were abundantly expressed in the kidney and in the urinary bladder and ventral pelvic skin. In an immunohistochemical study, the ENaC α-subunit protein was specifically localized to the apical membrane of the principal cells but not the intercalated cells from the late distal tubule to the collecting duct in the kidney or in the apical area of cells of urinary bladder epithelia. When toads were acclimated to dry and hyper-saline environments, the levels of ENaC mRNA expression in the kidney and urinary bladder decreased under hyper-saline acclimation, but not under dry conditions. Immunohistochemical observations indicated that the levels of ENaC protein expression were much lower in the apical area of renal distal tubules and urinary bladder epithelia of hyper-saline acclimated toad compared with controls. The present study suggests that Bufo ENaC is significantly expressed and functions during Na+ reabsorption in the apical membrane domain in the distal nephron of normal and desiccated toads. Natriuresis may be caused by decreases in ENaC expression and its trafficking to the cell surface in the distal nephron, a response to prevent excessive Na+ reabsorption in hyper-saline-acclimated toads.

Physiological and molecular mechanisms of inorganic phosphate handling in the toad Bufo bufo

Abstract: The aim of this study was to elucidate mechanisms of P(i) handling in toads (Bufo bufo). We introduced toads to experimental solutions of various [P(i)] and high P(i) diets and measured urine and lymph [P(i)]. Both lymph and urine [P(i)] increased with increasing P(i) loads, indicating P(i) absorption across skin and intestine. An initial fragment of a NaPi-II type transporter was amplified from kidney, and the full-length sequence was obtained. The protein showed the molecular hallmarks of NaPi-IIb transporters. When expressed in Xenopus oocytes the clone showed unusual pH dependence, but apparent affinity constants for P(i) and Na(+) were in the range of other NaPi-II transporters. Expression profiling showed that the transporter was present in skin, intestine and kidney. Reverse transcription-polymerase chain reaction assays on dissected renal tubules indicated expression in the collecting duct system. Collecting tubules and ducts were isolated, perfused and microelectrode recordings showed electrogenic P(i) transport in apical and basolateral membranes. Taken together, our results show that P(i) is handled by intestine, kidney and skin. The presently cloned NaPi-IIb is a likely candidate involved in P(i) absorption across these epithelia. In addition, electrophysiological experiments suggest that the collecting duct system plays an important role in P(i) homeostasis.

Comparison of ACE activity in amphibian tissues: Rana esculenta and Xenopus laevis.

Abstract: Angiotensin converting enzyme (ACE) is the dipeptidyl-carboxypeptidase of the renin-angiotensin system involved in the control of blood pressure and hydromineral metabolism. It converts angiotensin I to angiotensin II, the biologically active octapeptide. Angiotensin converting enzyme-like activity has been demonstrated in a wide range of vertebrates. The presence of ACE was investigated in tissues of two amphibian species, the frog Rana esculenta and the toad Xenopus laevis. ACE activities were determined by specific substrate hydrolysis in gut, gonads, lung, kidney, heart, liver, skin, erythrocytes, and muscle homogenates and plasma by means of high performance liquid chromatography. Significant ACE activity was found in gut, gonads, lung and kidney, while that in heart, liver, skin, erythrocytes, muscle, and plasma was very low. Testis of toad contained the highest ACE activity, while that in erythrocytes of male and female frogs was notable.

Antimicrobial activity of skin secretions isolated from Indian toad, Bufo melanostictus Schneider 1799

Abstract: Amphibians like toads have been known to secrete antimicrobial secretions outside their body into their environments, through skin pores and parotid glands. Toad skin-secretions contain four types of compounds namely, biogenic amines, bufadienolides, alkaloids & steroids and peptides & proteins. Bulk of research relating to amphibian antimicrobial secretions has been done on frogs. In toads, such research has only been done in South America, Europe and China. Antimicrobial secretions vary considerably from specie-to-specie and drastically across various biomes. This prompted us to examine and confirm presence of antimicrobial activity (if any) in Indian Common Toad (Bufo melanostictus Schneider 1799) skin secretions since; no such analysis had been previously done on this toad which is found all across the South-east Asia. The antibacterial potency of toad skin secretions was tested against the bacteria, Escherichia coli. After running preliminary antibacterial analysis assays, we found that these cutaneous secretions retrieved from Indian Common Toad possessed potential bactericidal activity. The results that we got confirmed that some unexplored bactericidal components were present in skin secretions of these toads. These conclusions call for further research into biochemistry and molecular characterization of these components.

The Formalin Test in African Toad (Bufo regularis) - a Novel Pain Model in Amphibians

Abstract: The formalin test was evaluated in African toad (Bufo regularis) with 37% formaldehyde (100% formalin) using a multi-dimensional motor activity scoring. The responses were biphasic like those obtained in rodents but with longer first phase, longer interval and longer second phase. Acetylsalicylic acid (70 mg kg ) reduced significantly responses in both phases while indomethacin only reduced the second 1 phase responses. The first phase is likely due to direct activation of nociceptors by formalin while the second phase suggests the involvement of inflammation. These results are similar to what has been observed in rodents although the physiological mechanisms may not be exactly the same. It is suggested that formalin test in toads is a valid experimental pain model in amphibians for the evaluation of longer-acting analgesics.

The thermal ecology of the Red-spotted toad, Bufo punctatus, across life history

Abstract: The Thermal Ecology of the Red-spotted Toad, Bufo punctatus, Across Life History by Candice Marie Rausch Dr. Frank van Breukelen, Examination Committee Chair Assistant Professor of Biology University of Nevada, Las Vegas Compared with other terrestrial vertebrates, amphibians are generally less tolerant of thermal extremes. The Mojave Desert has ambient temperatures outside the proposed thermal tolerance zone of its most abundant amphibian, the Red-spotted toad (Bufo (Anaxyrus) punctatus). Few data have been presented regarding the thermal ecology of these animals, including their thermal histories and proposed strategies to avoid temperature extremes. Previous studies suggest B. punctatus avoids extreme thermal exposure and adult toads experience body temperature (T^) below a proposed critical thermal maximum (CT„,^) of 35° C, and can maintain T ̂at 25° C during the winter. Further, previous studies indicate a CT„̂ „̂ for tadpoles of 33° C. A reassessment of the thermal ecology of Red-spotted toads was warranted based on personal observations reported in this thesis. I recorded environmental and/or Ty of Red-spotted toads across their entire life history: eggs, tadpoles, juveniles and adults. In the field, eggs and tadpoles may iii Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. encounter water temperatures as high as ~40° C. Juveniles can experience Ty as high as 42.2° C. Adult toads experience Ty as high as 39.1° C. These observations were combined with experimental determination of CT„,j,,,across life history statges; the CT„,̂ ,( of tadpoles was variable, but decreased as development progressed; adult toads exhibit a as high as 45.2 ± 1.0° C. I documented thermal preferences (Tp) of tadpoles and adults. In contrast to other studies of the effect of ontogeny on preferred temperature, Tp of Red-spotted toads remains fairly constant across development. I documented developmental time from egg deposition to metamorphosis at 18 days in the summer and 47 days in the spring both periods are less than the previously described 60-day developmental period. Finally, I present preliminary data on apparent basking-like behavior of late stage tadpoles in the field. Despite seemingly high and presumably stressful environmental temperatures. Redspotted toads do not generally live on the verge of thermal tolerance. However, later stage tadpoles may encounter potentially lethal temperatures. The collected data document the thermal ecology of Red-spotted toads and contradict previously assumed limits that may not have been experimentally-derived. These data may allow informed decision making in land use and conservation efforts by better defining an important ecological parameter in a species that may be subjected to increased pressures by human activity and climatic change.

Effect of bromocriptine on the larval skin of the green toad, Bufo viridis viridis leurenti.

Abstract: AL-ADHAMI M. A., QAR J. 2007. Effect of Bromocriptine on the Larval Skin of the Green Toad, Bufo viridis viridis Leurenti. Folia biol. (Krakow) 55: 41-46. In the premetamorphic larval green toad, B. viridis viridis, as in other anurans, the skin is made up of a fibrous dermis and an epidermis of stratified epithelium. The effects of bromocriptine, an antiprolactin drug, on the premetamorphic skin of B. viridis viridis was examined. Bromocriptine, dissolved in rearing water at four different concentrations, induced a number of changes in the skin of treated tadpoles. In rough sequence of appearance, these changes include: retraction of the melanocyte dendrites, synchronous burst of the apical vesicles of the superficial epithelial cells, gradual disappearance of the melanosomes from the epithelial cells and widening of the intercellular spaces. In addition, macrophages appeared in the superficial dermis amongst the retracted melanocytes. White crystals were observed on the skin surface and similar crystals were ingested by the macrophages. Prolonged treatment with bromocriptine resulted in hypertrophy and extraction of some epidermal cells. Deep melanocytes of the mesenteries were not affected by bromocriptine-treatment indicating that the drug did not penetrate deep into the tadpole tissue. Whether the macrophages observed in the dermis were recruited from deeper tissues or were converted melanocytes is another issue in need of study.

Biological effects of the Magnetic Stimulation on the Toad Heart

Abstract: We stimulated the exposed toad heart by a low frequency and high energy magnetic. By analyze the data of this experiment, it shows that the pulsating of the weak toad heart would make change after stimulated by magnetic. Weak heartbeat strengthened, the single peak curve would become the two peaks curve with atria wave and ventricle wave after the magnetic stimulation. But the cycling of rhythmic pulsatile curve of toad doesn't change.