Action of heparin and acetylcholine modulators on the neurotoxicity of the toad Rhinella schneideri (Anura: Bufonidae) in Brazil / Acción de la heparina y moduladores de acetilcolina en la neurotoxicidad del sapo Rhinella schneideri (Anura: Bufonidae) en Brasil

Abstract Introduction: Rhinella schneideri is a toad widely distributed in South America and its poison is characterized by inducing cardiotoxicity and neurotoxicity. Objective: In this work, we investigated pharmacological strategies to attenuate the peripheral neurotoxicity induced by R. schneideri poison in avian neuromuscular preparation. Methods: The experiments were carried out using isolated chick biventer cervicis preparation subjected to field stimulation for muscle twitches recordings or exposed to acetylcholine and potassium chloride for contracture responses. Results: Poison (10 μg/ml) produced complete neuromuscular blockade in chick biventer cervicis preparation within approximately 70 min incubation (times for 50 and 90 % blockade: 15 ± 3 min and 40 ± 2 min, respectively; P < 0.05, N= 5); contracture responses to exogenous acetylcholine and KCl were unaffected by poison indicating no specificity with postsynaptic receptors or myotoxicity, respectively. Poison (10 μg/ml)-induced neuromuscular blockade was not prevented by heparin (5 and 150 IU/ml) under pre- or post-treatment conditions. Incubation at low temperature (23-25 °C) abolished the neuromuscular blockade; after raising the temperature to 37 °C, the complete neuromuscular blockade was slightly slower than that seen in preparations directly incubated at 37 °C (times for 50 and 90 % blockade: 23 ± 2 min and 60 ± 2.5 min, respectively; P < 0.05, N= 4). Neostigmine (3.3 μM) did not reverse the neuromuscular blockade in BC preparation whereas 3,4-diaminopyridine (91.6 μM) produced a partial and sustained reversal of the twitch responses (29 ± 7.8 % of maximal reversal reached in approximately 40 min incubation; P < 0.05, N= 4). Conclusions: R. schneideri poison induces potent peripheral neurotoxicity in vitro which can be partially reversible by 3,4-diaminopyridine.

Resumen Introducción: Rhinella schneideri está ampliamente distribuida en Suramérica y su veneno es caracterizado por inducir cardiotoxicidad y neurotoxicidad. Objetivo: En este trabajo, investigamos estrategias farmacológicas para atenuar la neurotoxicidad periférica inducida por el veneno de R. schneideri en preparaciones neuromusculares de aves. Métodos: Los experimentos fueron realizados usando preparaciones de biventer cervicis de pollos sometidas a estimulación de campo para el registro de las contracciones musculares o expuestas a la acetilcolina y al cloruro de potasio para la respuesta contractural. Resultados: El veneno (10 µg/ml) provocó un bloqueo neuromuscular completo en las preparaciones después de aproximadamente 70 min de incubación (tiempos para 50 y 90 % de bloqueo: 15 ± 3 min y 40 ± 2 min, respectivamente; P < 0.05, N = 5); las contracturas en respuesta a la acetilcolina y el KCl exógenos no fueron afectadas por el veneno, indicando que no hay una interacción especifica con receptores postsinápticos o miotoxicidad respectivamente. El bloqueo neuromuscular causado por el veneno (10 µg/ml) no fue prevenido por la heparina (5 y 150 UI/ml) bajo condiciones pre y post-tratamiento. La incubación a bajas temperaturas (23-25 ºC) abolió el bloqueo neuromuscular; después de aumentar la temperatura a 37 ºC, el bloqueo neuromuscular total fue levemente más lento que el visto en preparaciones directamente incubadas a 37 ºC (tiempos para 50 y 90 % de bloqueo: 23 ± 2 min y 60 ± 2.5 min, respectivamente; P < 0.05, N= 4). Neostigmina (3.3 µM) no revirtió el bloqueo neuromuscular, mientras que 3.4-diaminopiridina (91.6 µM) produjo una reversión parcial y sostenida de las respuestas neuromusculares (29 ± 7.8 % de la reversión máxima alcanzada en aproximadamente 40 min de incubación; P < 0.05, N = 4). Conclusiones: El veneno de R. schneideri indujo neurotoxicidad periférica potente in vitro, el cual puede ser revertido por 3.4-diaminopiridina.

Atividade antimicrobiana in vitro de extratos metanólicos de secreções cutâneas de anfíbios amazônicos sobre fitopatógenos de interesse agrícola / n vitro antimicrobial activity of methanolic extracts from cutaneous secretions of Amazonian amphibians against phytopathogens of agricultural interest

Os mecanismos de defesa bioquímica dos anfíbios envolvem secreções cutâneas de moléculas bioativas com atividade antimicrobiana. Este estudo avaliou a atividade in vitro de extratos metanólicos da secreção cutânea de duas espécies de anfíbios da família Bufonidae, Rhaebo guttatus e Rhinella marina, no controle dos patógenos Fusarium udum, Fusarium solani, Colletotrichum truncatum, Aspergillus flavus, Rhizoctonia solani, Macrophomina phaseolina e Calonectria pseudometrosideri. O extrato de R. guttatus inibiu o crescimento micelial de F. udum, F. solani, A. flavus e M. phaseolina em algumas concentrações testadas. O extrato de R. marina inibiu o crescimento micelial de C. truncatum na concentração de 0,5 mg mL- ¹, e inibiu o crescimento micelial de A. flavus nas concentrações de 0,1 e 0,5 mg mL- ¹, que foi semelhante à inibição pelo controle positivo. O extrato de R. marina também diminuiu a produção de microescleródios de R. solani nas concentrações de 0,2 e 0,3 mg mL- ¹. Além disso, os extratos inibiram a esporulação e germinação de conídios em graus variados. A inibição da formação de apressórios em C. truncatum pelos extratos de R. guttatus e R. marina foi de 85%­99% e 63%­100%, respectivamente. Nossos resultados demonstraram que o tratamento com extratos da secreção cutânea de R. guttatus e R. marina apresentou atividade antifúngica sobre os fitopatógenos estudados.(AU)

Ocorrência de Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) em Rhinella icterica (Spix, 1824) (Anura: Bufonidae) em Maricá, Rio de Janeiro, Brasil / Occurrence of Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) in Rhinella icterica (Spix, 1824) (Anura: Bufonidae) in Maricá, Rio de Janeiro, Brazil / Ocurrencia de Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) en Rhinella icterica (Spix, 1824) (Anura: Bufonidae) en Maricá, Río de Janeiro, Brasil

Anfíbios anuros são comumente parasitados por carrapatos da espécie Amblyomma rotundatum, os quais possuem alta predileção por animais ectotérmicos. Fêmeas e ninfas ingurgitadas de A. rotundatum foram coletadas em condições naturais a partir de um espécime de "sapo-cururu" da espécie Rhinella icterica. A identificação dos carrapatos foi feita por meio de características morfológicas. Este é o primeiro relato do parasitismo deste carrapato em sapos desta espécie no Município de Maricá, Região Metropolitana do Estado do Rio de Janeiro, Brasil.(AU)

Anuran amphibians are commonly parasitized by ticks of the species Amblyomma rotundatum, which have high predilection for ectothermic animals. Engorged females and nymphs of A. rotundatum were collected under natural conditions from a "toad-cururu" specimen of the species Rhinella icterica. The identification of ticks was made through morphological characteristics. This is the first report of the parasitism of this tick in toads of this species in the Municipality of Maricá, Metropolitan Region of the State of Rio de Janeiro, Brazil.(AU)

Los anfibios anuros son comúnmente parasitados por garrapatas de la especie Amblyomma rotundatum, los cuales poseen alta predilección por animales ectotermos. Las hembras y ninfas ingurgitadas de A. rotundatum fueron recolectadas en condiciones naturales a partir de un espécimen de "sapo cururú" de la especie Rhinella icterica. La identificación de las garrapatas se ha hecho a través de características morfológicas. Este es el primer relato del parasitismo de esta garrapata en sapos de esta especie en el Municipio de Maricá, Región Metropolitana del Estado de Río de Janeiro, Brasil.(AU)

Morphological characterization of Eustrongylides sp. larvae (Nematoda, Dioctophymatoidea) parasite of Rhinella marina (Amphibia: Bufonidae) from Eastern Amazonia / Caracterização morfológica de larva de Eustrongylides sp. (Nematoda, Dioctophymatoidea) parasita de Rhinella marina (Amphibia: Bufonidae) da Amazônia Oriental Brasileira

Absctract Eustrongylides spp. nematodes have birds as final hosts and uses other vertebrates as intermediate/paratenic host (fish, amphibians and reptiles) and have zoonotic potential. In amphibians, the larvae may be located in the subcutaneous tissues, liver and mesentery, between the muscle fibres, especially in the lower limbs. Rhinella marina, which is widely observed in Brazil, has exhibited complex diversity in its helminth fauna, reflecting the unique habitat of the Amazon biome. For the first time, this study describes the morphological aspects of third-stage larvae of Eustrongylides sp. in Rhinella marina from Santa Cruz do Ararí, Marajó Archipelago, Eastern Amazonia, using light and scanning electron microscopy.

Resumo Os nematoides do gênero Eustrongylides tem as aves como seus hospedeiros definitivos e utilizam outros vertebrados como hospedeiros intermediários/paratênicos (peixes, anfíbios, répteis), além de apresentar potencial zoonótico. Em anfíbios, as larvas podem estar localizadas em tecidos subcutâneos, fígado, mesentério e entre fibras musculares de membros inferiores. Rhinella marina, anfíbio o qual é distribuído amplamente no Brasil, apresenta uma complexa diversidade em sua helmintofauna, refletindo o seu hábitat no bioma amazônico. O presente estudo descreve, pela primeira vez, os aspectos morfológicos das larvas de terceiro estágio de Eustrongylides sp. em R. marina de Santa Cruz do Arari, Arquipélago do Marajó, Amazônia Oriental Brasileira, utilizando-se microscopia de luz e microscopia eletrônica de varredura.

Antiplasmodial and Cytotoxic Activities of Toad Venoms from Southern Amazon, Brazil

The drug-resistance of malaria parasites is the main problem in the disease control. The huge Brazilian biodiversity promotes the search for new compounds, where the animal kingdom is proving to be a promising source of bioactive compounds. The main objective of this study was to evaluate the antiplasmodial and cytotoxic activity of the compounds obtained from the toad venoms of Brazilian Amazon. Toad venoms were collected from the secretion of Rhinella marina and Rhaebo guttatus in Mato Grosso State, Brazil. The powder was extracted at room temperature, yielding 2 extracts (RG and RM) and a substance ('1') identified as a bufadienolide, named telocinobufagin. Growth inhibition, intraerythrocytic development, and parasite morphology were evaluated in culture by microscopic observations of Giemsa-stained thin blood films. Cytotoxicity was determined against HepG2 and BGM cells by MTT and neutral red assays. The 2 extracts and the pure substance ('1') tested were active against chloroquine-resistant Plasmodium falciparum strain, demonstrating lower IC₅₀ values. In cytotoxic tests, the 2 extracts and substance '1' showed pronounced lethal effects on chloroquine-resistant P. faciparum strain and low cytotoxic effect, highlighting toad parotoid gland secretions as a promising source of novel lead antiplasmodial compounds.

A new species of Mesocoelium (Digenea: Mesocoeliidae) found in Rhinella marina (Amphibia: Bufonidae) from Brazilian Amazonia

Mesocoelium lanfrediae sp. nov. (Digenea: Mesocoeliidae) inhabits the small intestine of Rhinella marina (Amphibia: Bufonidae) and is described here, with illustrations provided by light, scanning electron microscopy and molecular approachs. M. lanfrediae sp. nov. presents the typical characteristics of the genus, but is morphometrically and morphologically different from the species described previously. The main diagnostic characteristics of M. lanfrediae sp. nov. are (i) seven pairs of regularly-distributed spherical papillae on the oral sucker, (ii) ventral sucker outlined by four pairs of papillae distributed in a uniform pattern and interspersed with numerous spines, which are larger at the posterior margin and (iii) small, rounded tegumentary papillae around the opening of the oral sucker, which are morphologically different from those of the oral sucker itself, some of which are randomly disposed in the ventrolateral tegumentary region of the anterior third of the body. Addionally, based on SSU rDNA, a phylogenetic analysis including Brachycoeliidae and Mesocoeliidae taxa available on GenBank established the close relationship between M. lanfrediae sp. nov. and Mesocoelium sp.

Ornithophagy in Rhinella icterica / Ornitofagia em Rhinella icterica

In this work we report an observation of an ornitophagy event on Certhiaxis cinnamomeus by Rhinella icterica occurred in the central region of Rio Grande do Sul, Brazil.

Reportamos um evento de ornitofagia por Rhinella icterica sobre Certiaxis cinnamomeus ocorrido em 2010, na região central do Estado do Rio Grande do Sul (29°41S, 53°48W), Brasil.

Evaluación de los efectos de diversas intensidades de estimulación nerviosa sobre la amplitud de la respuesta en diferentes especies / Evaluation of the effects of various intensities of nerve stimulation on the scale of the response in different species

El comportamiento nervioso a la estimulación eléctrica ha sido ampliamente estudiado desde 1840, época en la que se comienza a entender las características de la amplitud de respuesta nerviosa y velocidades de conducción en nervios de animales. La amplitud de respuesta en segmentos de nervios es producto de los potenciales de acción compuestos resultantes a la estimulación eléctrica. En esta investigación se estudió el comportamiento nervioso a potenciales evocados in vivo en humanos (nervio ulnar) e in vitro como nervio aislado en Bufus marinus. Durante la estimulación de los nervios se encontró respuesta de comportamiento cualitativo creciente y heterogéneo intra e ínter-especie. El análisis de las respuestas y mecanismos que participan en estos resultados se discuten.

Nervous behaviour by electrical stimulation has been widely studied since 1840, times that initiated the comprehension of the conduction velocity and nerve's amplitude responses in animals. The amplitude response in nerve segments electrically stimulated is generated by the result of composed action potentials. This research pretended to study the nerve responses to evoked potentials in human in vivo (ulnar nerve) and in vitro in animals (Bufus marinus) in sciatic nerve. Electrical stimulation resulted in rising responses of heterogeneous quality inter and intra-species. Mechanisms involved in each response are examined.

Effects of azadirachtin on mortality, fertilization, and swimming speed in larvae of the cane toad, Bufo marinus (Anura: Bufonidae).

Experiments were conducted to assess the effects of azadirachtin (AZ) on survival capacity, fertilization success, and swimming speed in larval stages of the cane toad, Bufo marinus . LC50 values (96-hr) for various larval stages exposed to 0.50 mg/l AZ were as follows: 5.35 (stage 12), 5.77 (stage 16), 787 (stage 20), 13.43 (stage 24), and 21.54 (stage 30). Tadpoles did not exhibit any apparent disorientation or production of mucous in response to AZ concentrations ranging from 0.3 to 0.5 mg/l. Mortality was significantly higher at 0.50 mg/l AZ than at lower concentrations. At 0.50 mg/l, mortality rate decreased significantly from 36% for stage 12 tadpoles, to 24% for stage 20 tadpoles. Mortality for early stages (stage 12) dropped significantly, from 36% at 0.50 mg/l, to 21% at 0.40 mg/l AZ There were no significant differences in percent mortality for any developmental stage at an AZ concentration of 0.3 mg/l, or for controls (no AZ). Exposure of gametes to 0.30 mg/l AZ did not reduce fertilization success as compared to controls (89.8 vs. 83.7%). At 0.40 mg/l, percent fertilization decreased significantly (68.8%). This effect was even more pronounced at 0.50 mg/l. No significant difference was found in swimming speeds between controls and subjects exposed to 0.30 mg/l AZ. However, at a concentration of 0.40 mg/l, tadpoles required a significantly longer period of time to swim a distance of 140 cm as compared to controls. The potential impact of AZ on amphibian populations is discussed.

Resting respiratory behavior in minimally instrumented toads - effects of very long apneas on blood gases and pH

Resting respiratory behavior of Bufo marinus in minimally instrumented toads is described for a period of 24 hours in which the animals are left undisturbed. Torpor-related long apneas are described and their implications for blood gas levels are investigated. Results show that the resting ventilation rate of Bufo marinus is much lower than that reported so far. Levels of arterial oxygen, carbon dioxide, and pH are monitored during artificial long apneas induced by anesthesia. The toads showed an unexpected ability to unload carbon dioxide by non-respiratory means, even while being kept on dry plastic box with no access to water. Oxygen arterial partial pressure dropped to very low levels after one hour of apnea. This suggests that these animals may endure very well severe hypoxia for long periods of time while in torpor

Ventilatory behaviors of the toad Bufo marinus revealed by coherence analysis

Breathing in amphibians is a remarkably complex behavior consisting of irregular breaths that may be taken singly or in bouts that are used to deflate and inflate the lungs. The valves at the two outlets of the buccal cavity (nares and glottis) need to be finely controlled throughout the bout for the expression of these complex respiratory behaviors. In this study, we use a technique based on the calculation of the coherence spectra between respiratory variables (buccal pressure; narial airflow; and lung pressure). Coherence was also used to quantify the effects of chemoreceptor and pulmonary mechanoreceptor input on narial and glottal valve behavior on normoxic, hypoxic, and hypercapnic toads with both intact and bilaterally sectioned pulmonary vagi. We found a significant reduction in narial coherence in hypoxic vagotomized toads indicating that pulmonary mechanoreceptor feedback modulates narial opening duration. An unexpectedly high coherence between Pl and Pb during non-respiratory buccal oscillations in hypercapnic toads indicated more forceful use of the buccal pump. We concluded that the coherence function reveals behaviors that are not apparent through visual inspection of ventilatory time series

Las glandulas de la mucosa dorso-distal de la lengua del sapo Bufo marinus L. (Amphibia: Anura): histologia y ultraestructura / The glands of the dorso-distal mucosa of the toad Bufo marinus (Amphibia: Anura) tongue: histology and ultrastructure

RESUMEN: Frecuentemente, los estudios realizados en la ultraestructura del epitelio dorsal no-sensorial de la lengua de anuros no muestran las diferencias existentes entre el epitelio que reviste la papila filiforme y el epitelio que cubre la pared glandular. Para estudiar el epitelio glandular, muestras de la mucosa dorso-distal de la lengua de Bufo marinus fueron procesadas para microscopía electrónica de transmisión y cortes gruesos y finos fueron coloreados para analizarlos con microscopía de luz y electrónica. Los resultados mostraron claramente que el epitelio glandular se encuentra formado por tres diferentes tipos de células: (1) células secretoras granulares serosas; (2) células ricas en mitocondrias (CRM) y (3) células ciliadas. Se expone la estructura detallada de cada tipo celular bajo microcopía de luz y electrónica. Es de hacer notar que en la porción lingual estudiada, las células secretoras no mostraron signos de exocitosis de sus gránulos secretores, lo que sugiere que estas células no tienen una actividad secretora basal o continua. Adicionalmente la distribución, localización y estructura de las CRM sugieren su participación en la maduración y/o función de las células secretoras.

Los mastocitos de la lengua del sapo Bufo marinus L: caracterizacion histoquimica de glicoconjugados con tecnicas convencionales y con lectinas / The tongue mast cells of Bufo marinus L. toad: characterization of glycoconjugates with conventional and lectin methods

Mast cell populations in mammals have been recognized as morphologically and functionally heterogeneous. In situ characterization of these cell type carbohydrates with conventional histochemical techniques and with lectin histochemistry has not been afforded in amphibian species. Different conventional staining methods for complex carbohydrates and 18 different, biotin or peroxidase conjugated, lectins were used in paraffin embedded Rossman fluid-fixed sections of mid-central region of the toad tongue. Conventional carbohydrate histochemistry showed a single type of mast cells with a variable concentration of highly sulphated glycosaminoglycans. Lectin histochemistry showed partial heterogeneity in the mast cell population. Most cells contain N-linked and O-linked oligosaccharides with variable quantities of Man but high of GlcNAc and terminal Gal-beta (1,3)-GaINAc residues. A considerable number of mast cells showed proteins or oligosaccharides with terminal sialic acid residues but only few mast cells contain terminal fucose. Discussion is made comparing these results with similar histochemical studies and with functional experimental studies performed in human and rat mast cells

Evidencias que sugieren una asociacion microanatomica mastocito-nervio en la lengua del sapo Bufo Marinus demostradas mediante microscopia de luz de alta resolucion / Suggestive evidences for a microanatomical relationship between mast cells and nerve in the tongue of the toad Bufo Marinus demonstrated by means of high resolution light microscopy

Los mastocitos son células del tejido conectivo presentes en todos los vertebrados y caracterizados por la coloración metacromática de sus gránulos. Actualmente están reconocidos como potentes productores de múltiples citocinas, sugiriendo un papel importante en la inmunoregulación y en la defensa del hospedador. Estas células han sido descritas preferentemente localizadas alrededor de los vasos sanguíneos pero recientemente se han reportado relaciones espaciales próximas entre mastocitos y nervios mayoritariamente refe-ridos a mamíferos. En este trabajo se estudia, mediante microscopía de luz de alta resolución, la anatomía microscópica de los mastocitos asociados al tejido nervioso, en la lengua del sapo Bufo marinus. La población de mastocitos fue identificada en los cortes semifinos incluidos en Epon por la tinción metacromática de sus gránulos citoplasmáticos al ser contrastados con Azul de Toluidina y Azure A. Se observaron numerosos mastocitos dispersos a través de la región submucosal, adyacentes y/o dentro de paquetes nerviosos y de ganglios nerviosos, cerca de fibras musculares esqueléticas y adyacentes a vasos sanguíneos. Adicionalmente, se observaron mastocitos adyacentes a fibras nerviosas mielínicas conspicuas e individuales, bajo el endotelio de los vasos linfáticos, siendo éste aparentemente, un evento previamente no reportado. Los resultados sugieren que las asociaciones mastocitos-nervios son funcionalmente importantes en la lengua del sapo.

Nuevas observaciones en la estructura del epitelio de las papilas filiformes de la lengua del sapo Bufo marinus L: estudio con microscopia de luz y electrónica de transmisión / New observations on the structure of the lingual filiform papillae epithelium of the toad Bufo marinus L: Light and transmission electron microscopy study

Existen inconsistencias y confusiones acerca de la estructura microscópica del epitelio de la mucosa dorsal lingual no-sensorial en anuros. El objetivo de este trabajo fue diferenciar la estructura del epitelio de revestimiento papilar de la del epitelio glandular y para ello, muestras de la mucosa dorsal distal de la lengua de Bufo marinus fueron procesadas para microscopía electrónica de transmisión (MET) y para microscopía de luz (ML), utilizando cortes coloreados de 1 _m. Los resultados mostraron que las papilas filiformes están revestidas por un epitelio biestratificado formado por un estrato basal de células dendríticas y un estrato superficial constituido por una mayoría de células secretoras seromucosas, prolongaciones apicales de células dendríticas además de algunas células caliciformes y ciliadas. Con ML la mayoría de las papilas filiformes mostraban células secretoras seromucosas en aparente reposo. Estas células se caracterizaron por tener núcleo basal redondeado, citoplasma pálido y con gránulos pequeños, dispersos y coloreados en la región supra-nuclear. Con el MET las células seromucosas mostraron RER poco desarrollado, gránulos de mediana electrón densidad y microcrestas en el borde apical. Las células dendríticas se observaron como células ramificadas que rodean completamente la superficie basolateral de las células secretoras superficiales y cuyos procesos apicales terminan en microvellosidades. Las tecas de células semejantes a células caliciformes mostraron una red continua de gránulos secretores medianamente electrón densos, parcialmente fusionados y algunos procesos en forma de microvellosidades irregulares en el borde apical. Las células ciliadas aparecieron localizadas en su mayoría, en la pared lateral de la papila filiforme. Los resultados sugieren que en la papila filiforme existen interacciones yuxtacrinas o paracrinas, mediadas por contacto físico, entre células dendríticas y secretoras.

Fast and slow voltage modulation of apical Cl- permeability in toad skin at high [K+]

The influence of voltage on the conductance of toad skin was studied to identify the time course of the activation/deactivation dynamics of voltage-dependent Cl- channels located in the apical membrane of mitochondrion-rich cells in this tissue. Positive apical voltage induced an important conductance inhibition which took a few seconds to fully develop and was instantaneously released by pulse inversion to negative voltage, indicating a short-duration memory of the inhibiting factors. Sinusoidal stimulation at 23.4 mM [Cl-] showed hysteresis in the current versus voltage curves, even at very low frequency, suggesting that the rate of voltage application was also relevant for the inhibition/releasing effect to develop. We conclude that the voltage modulation of apical Cl- permeability is essentially a fast process and the apparent slow components of activation/deactivation obtained in the whole skin are a consequence of a gradual voltage build-up across the apical membrane due to voltage sharing between apical and basolateral membranes.

Interactions between body temperature regulation and blood acid-base status in anuran amphibians

In vertebrate evolution, the transition from aquatic to terrestrial mode of life was associated with considerable changes in the respiratory system and CO2/pH-sensitive receptors became fundamental. The present review focuses on the combined effects of hypercapnia and body temperature in anuran amphibians, that represent a key group for the transition. Recent studies have indicated that temperature affects the hypercapnic drive to breathe. Conversely, hypercapnia modulates the range of preferred body temperature of amphibians and central (CO2/pH) receptors are likely to be involved.

Histoquimica de lectinas en la lengua del sapo Bufo marinus L / Lectin histochemical of the cane toad Bufo marinus L. tongue

Lectin histochemistry at light microscope level was used in the tongue of the cane toad Bufo marinus to determine the distribution of sugar residues in glycoconjugates (GCs) previously localized and characterized by conventional histochemical techniques. Five horseradish-peroxidase (HRP)labeled-lectins, namely Con A, PNA, SBA, UEA-1 and WGS were used. Additionally, neuraminidase (N) treated sections before the staining procedures were used in order to dilucidate the presence of terminal sialic acid (SA). Sugar residues in GCs of the taste organ (TO) associated mucous cells stained more intensely with WGA than with Con A and UEA-1. All the sensory cells reacted with Con A and WGA but one type of them were characteristically labeled by UEA-1. The glycocalix (gc) of the TOs resulted ensely stained with Con A and with WGA and UEA-1 before and after N treatment. The GCs in the mucous-supporting cells of dorsal mucosae filiform papillae and folds reacted intensely with WGA and weakly with Con A. The ciliated cells (cic) were intense and characteristically stained with UEA-1 and WGA and moderately with Con A. The gc reacted more intensely with WGA than with Con A. Dorsal mucosae glands secretory cells mucins were characteristically stained with PNA, SBA and WGA besides Con A, while glandular ciliated cells showed the same staining pattern as in the filiform papillae. In the ventral mucosa all epithelium cells resulted stained with WGA and Con A, while differentiated goblet cells only reacted as well with UEA-1 and PNA before and after neuraminidase treatment. Unexpectedly, cliated ventral ucosae cells did not react with UEA-1 but only with WGA and Con A. The results have shown that lectin histochemistry is an interesting tool to characterize similarities and differences in the lingual GCs sugar residues composition and distribution, particularly those located in epithelial cells

Caracterizacion histoquimica de los glicoconjugados de la lengua del sapo Bufo marinus L. (Anfibio, Anuro) con tecnicas convencionales para microscopia de luz / Histochemical characterization of glycoconjugates in the tongue of the toad Bufo marinus L. (Amphibian, Anuran) with conventinonal techniques for light microscopy

Histochemical stains with and without enzymatic digestions such as alpha-amylase, neuraminidase and hyaluronidase, made possible to localize and differentiate various types of glycoconjugates (GCs) in the tongue of the toad Bufo marinus. In the dorsal mucosae the covering epithelium of the filiform papillae, of the central folds and in the marginal cells of the fungiform papillae there were present large amounts of neutral GCs with little or no galactose and/or N-acetylgalactosamine and scanty carboxylic acid GCs while the superficial strata of the taste organs showed a mixture of neutral an acid GCs with a predominance of sulfated and carboxylic acid GCs. The glandular secretory cells showed neutral GCs almost exclusively with a gradient of concentrations increasing from the base to the apex being galactose or N-acetyl-galactosamine one of the component sugars. The ventral epithelium showed two types of mucous cells, one with neutral GCs and the other with neutral and acidic GCs. The connective tissue contained many mast cells showing highly acid GCs both sulfated and carboxilic with some neutral GCs. The extracellular connective matrix showed scanty neutral and acid GCs. Glycogen was present in the cytoplasm of glandular epithelial cells and of the striated muscle fibers. Additionally, the obtained results suggest the presence of a type of GC with a carboxylic acid (sialic acid) resistant to neuraminidase of Clostridium perfringens used in this study.