中华大蟾蜍消化道嗜银细胞的形态与分布

目的:探索中华大蟾蜍消化道嗜银细胞的形态与分布规律。方法:应用龙桂开浸银法对中华大赡蜍消化道各部进行石蜡包埋切片和显微观察测量。结果:嗜银细胞分布于胃贲门及以下所有消化管。胃、十二指肠与小肠末段分布密度较高。在胃主要分布于胃腺粘液细胞之间或其附近,其它部位分布于粘膜上皮和肠腺,其中十二指肠始端肠腺内有高密度分布小区。嗜银细胞常有突起,细胞形态与其所在位置有关。嗜银细胞可见向消化管腔或其周边释放嗜银颗粒的现象。结论:嗜银细胞在消化管的两端分布多而中肠少,其形态可能与其所受挤压情况有关,其体积与其分布密度呈正相关;嗜银细胞的分泌物或通过消化管腔液发挥作用,或通过旁分泌形式发挥作用。     

Blood-group A and G specific structures in toad (Bufo) spawn. Comparative studies on three species (Bufo bufo, Bufo viridis, Bufo calamita)

Permethylation analyses of the spawn material of three toad (Bufo) species allow the conclusion that the serologically determinant group in Bufo bufo spawn is identical with that found in human and hog blood-group A substances (i.e. GalNAc(alpha1,3) [Fuc(alpha1,2)] Gal -), and the serologically determinant group in Bufo viridis and Bufo calamita spawn is identical with that found in blood-group H substances (i.e. Fuc(alpha1,2) Gal -).     

Lectin binding patterns in amphibian skin epithelium.

Seven lectins (PNA, DBA, WGA, UEA-I, RCA, SBA, Con A) were used to localize glycoconjugates in the skin of 10 species of Amphibia, 7 anurans (Bufo marinus, Bufo bufo, Rana ridibunda, Rana pipiens, Hyla arborea, Pelobates syriacus and Xenopus laevis) and 3 urodeles (Salamandra salamandra, Triturus vulgaris and Ambystoma mexicanum). It was found that every lectin has a specific binding pattern in the skin of each species. No common pattern could be established, either among frogs or toads, nor for a particular lectin. Each lectin bound specifically and selectively to a particular epithelial component, which differed from one species to the other. A number of lectins showed selective binding to mitochondria-rich cells, but, again, a pattern in positivity could not be found. It is concluded that lectin histochemistry does correlate with cellular function. Our data can be applied in studies of epithelium and skin development, and of changes that occur during adaptation to the environment by amphibian species.     

Pineal-retinal molecular relationships: distribution of "S-antigen" in the pineal complex

The immunocytochemical localization of S-antigen, a specific protein first discovered in retinal photoreceptors, was studied in the pineal complex of vertebrates (eel, pike, frog, lizard, passerines, mouse, hamster) using monoclonal antibody immunofluorescence. S-antigen immunoreactivity was demonstrated concurrently in retinal photoreceptors and in most pineal phototransducers of all species, i.e. in pineal cells of the receptor series (cone-like, modified photoreceptor cells, pinealocytes) and in cone-like photoreceptors of the frog frontal organ and lizard parietal eye. The labelling was distributed either in all compartments of these cells, or restricted to outer segments. The functional significance of the S-antigen as well as some phylogenetic and ontogenic implication of this marker are discussed.     

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

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.     

Development of Harderian gland during metamorphosis in anurans

Development of Harderian gland of larvae of Rana japonica, Bufo bufo japonicus, and Xenopus laevis was studied. In the adult animals, well-developed Harderian glands were invariably present in the orbit. In Rana and Bufo, the gland first appeared at late prometamorphic stage and in Xenopus it appeared around climax stage. In thyroidectomized tadpoles of Bufo and Rana, the Harderian gland was induced by thyroxine. In hypophysectomized tadpoles of Bufo the gland developed when they were treated with thyroxine or TSH.     

Corticosterone stimulates the development of preoptic catecholamine neurons in tadpoles Bufo bufo japonicus

Summary In Bufo bufo japonicus catecholamine neurons in the preoptic recess organ (PRO) became detectable at the metamorphic climax by formaldehyde-induced fluorescence (Falck-Hillarp technique). In hypophysectomized tadpoles metamorphosis was inhibited and no fluorescent neurons appeared in the PRO. Implantation of a pituitary graft to the hypophysectomized tadpoles induced metamorphosis and development of PRO catecholamine neurons. Administration of corticosterone to hypophysectomized tadpoles resulted in the development of PRO catecholamine neurons in spite of the unmetamorphosed state. On the other hand, prolactin administration had no effect on the PRO neurons of hypophysectomized tadpoles. From these results, in conjunction with our previous results indicating that thyroxine treatment induces development of the PRO catecholamine neurons in thyroidectomized animals but not in hypophysectomized animals, it is concluded that corticosterone is a primary hormone for the development of PRO catecholamine neurons in toad tadpoles.     

Intracellular sodium and potassium concentrations in toad and frog oocytes during development

1. During growth of oocytes of Bufo bufo from approximately 700-2000 mum in diameter, intracellular Na rose from 20 to 120 m-mole/l. cell water while K fell from 120 to 15 m-mole/l. cell water.2. In Rana temporaria Na similarly rose from 9 to 190 m-mole/l. cell water and K fell from 126 to 28 m-mole/l. cell water.3. At the same time in both Bufo and Rana the ouabain-sensitive Na efflux, the ouabain-insensitive Na efflux, and the total Na influx all increased.4. It is concluded that the predominant process is an increase of passive Na permeability. The increase of apparently active Na efflux may be secondary to the consequent rise in intracellular Na.     

Localization of calcium in fibrocytes associated with the "substantia amorpha" in the skin of toad, Bufo bufo (L.) (Amphibia, Anura)

Using the potassium pyroantimonate-technique in the fibrocytes associated with the calcium-containing granules of the substantia amorpha within the dermis of Bufo bufo numerous electron-dense deposits have been observed. Reaction product lies in the mitochondria, at the plasma membranes and in various vesicular structures. X-ray microanalysis confirmed that pyroantimonate was predominantly associated with calcium. It is suggested that certain organelles of the fibrocytes are capable of sequestering calcium ions and that the fibrocytes are involved in the Ca-metabolism of the substantia amorpha.     

Zum Wirkungsmechanismus der Etacrynsäure

Zusammenfassung An der isolierten Bauchhaut der Erdkröte (Bufo bufo) wurden im Ussingschen Modell der Einfluß von Etacrynsäure und Furosemid auf Potentialdifferenz und Kurzschlußstrom gemessen. Je nach Ort der Zugabe (Innen- oder Außenseite der Membran) ergaben sich deutliche Wirkungsunterschiede. Insgesamt weisen die Ergebnisse darauf hin, daß an der isolierten Haut von Amphibien neben einem Einfluß auf den aktiven Natriumtransport Änderungen der Permeabilitätsverhältnisse für passive Ionenbewegungen als Erklärung für die Wirkungsweise der beiden Diuretica angenommen werden müssen.

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Summary Using the ventral skin of the European toad (Bufo bufo) in the Ussing model the influence of the diuretics Furosemide and Etacrynic acid on the membrane potential and the short-circuit-current were investigated. A marked difference in response of the two parameters was observed in regard to the side of the membrane (inside—outside) to which the drug was added. In addition the results indicate that aside from the influence of the two drugs on active sodium transport changes in the permeability of the skin for passively moving ions have to be assumed.

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Herrn Professor Dr.H. Schwiegk zum 60. Geburtstag gewidmet.     

Intracellular sodium and potassium concentrations in oocytes of Bufo bufo at the beginning of maturation

1. During the first phase of maturation in oocytes of Bufo bufo, after the growth phase but before ovulation, intracellular Na rises to 120 m-mole/l. cell water while K falls to 15 m-mole/l. cell water.2. At the same time, the ouabain-insensitive Na efflux and total Na influx both increase while the ouabain-sensitive Na efflux is unchanged.     

Relative Koordination der Lymphherzbewegungen bei Anuren

Zusammenfassung 1. Die Registrierung der Pulsrhythmen der coccygealen Lymphherzen von Rana temporaria, R. esculenta, R. ridibunda, Bufo bufo, B. calamita und B. viridis ergab gattungstypische Unterschiede.2. Die Pulse der coccygealen Lymphherzen der Anuren zeigen relative Koordination, wie sie für somatisch innervierte Lokomotionsorgane bekannt war.3. Es ist wahrscheinlich, daß zwischen den coccygealen Lymphherzzentren koordinierende nervöse Verbindungen bestehen, wie sie für die homolateralen bekannt waren. Es scheint sich um intraspinale Bahnen zu handeln, die eine zu den homolateralen Bahnen differente Ausbildung zeigen.4. Die Erregungsleitung dieser interzentralen Bahnen wird durch Impulse aus dem Gehirn blockiert, eine Hemmung, die durch Narkose und Dekapitierung beseitigt wird.5. Bei Kröten der Gattung Bufo treten von Erregungszuständen abhängige charakteristische Doppelsystolen (Extrasystolen) auf, die als Phänomene der relativen Koordination (Bigemini) zu verstehen sind.

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Summary 1. Recording the beats of the coccygeal lymph hearts of Rana temporaria, R. esculenta, R. ridibunda, Bufo bufo, B. viridis and B. calamita, genustypical differences were found.2. The pulsations of the anuran coccygeal lymph hearts show relative Koordination which has been known for locomotion-organs with somatic innervation.3. There seem to be coordinating nervous connexions between the spinal centers of the lymph hearts. In comparison to the known homolateral ones they are of a different type.4. The conduction by the intercentral connexions is blocked by cerebral impulses. In spinal animals and after narcosis the block is removed.5. The lymph hearts of toads (genus Bufo) show, depending on the degree of excitation, characteristic paired systoles which are phenomenons of the relative Koordination (Bigemini).

     

Ultrastructure of the gut caecal epithelium of Pricea multae (Monogenea: Polyopisthocotylea)

 Ultrastructural observations of the gut caecal epithelium of Pricea multae revealed the presence of pigmented and non-pigmented digestive cells. The pigmented digestive cells were separated by a connecting syncytium and appeared elongated,with numerous vesicles appearing toward the apical cell surface. They were characterised by granular inclusions in the form of electron-dense pigments, which were eliminated by exocytosis. These cells and their lamellar connecting syncytium were observed projecting into the gut lumen. Transverse sections of the gut epithelium revealed intact portions of digestive cells lying in the lumen. Endocytosis at the apical surface of the pigmented digestive cells gave rise to the formation of granular inclusions, which appeared as electron-dense pigments confined to lysosomal vesicles within the digestive system. Electron X-ray microanalysis indicated these granules were primarily composed of iron, demonstrating that P. multae is a blood-feeder. The connecting syncytium, while probably involved in a structural, supportive role, may additionally function in the absorption of micromolecular nutrients from the host blood meal. Received: 20 June 1995 / Accepted: 3 November 1995     

Variations in photoreceptor response dynamics across the fly retina

Gradients in the spatial properties of retinal cells and their relation to image statistics are well documented. However, less is known of gradients in temporal properties, especially at the level of the photoreceptor for which no account exists. Using light flashes and white-noise-modulated light and current stimuli, we examined the spatial and temporal properties of a single class of photoreceptor (R1-6) within the compound eyes of male blowfly, Calliphora vicina. We find that there is a trend toward higher performance at the front of the eye, both in terms of spatiotemporal resolution and signal-to-noise ratio. The receptive fields of frontal photoreceptors are narrower than those of photoreceptors at the side and back of the eye and response speeds are 20% faster. The signal-to-noise ratio at high frequencies is also greatest at the front of the eye, allowing a 30-40% higher information rate. The power spectra of signals and noise indicate that this elevation of performance results both from shorter responses to individual photons and from a more reliable registration of photon arrival times. These distinctions are characteristic of adaptational changes that normally occur on increasing illumination. However, all photoreceptors were absorbing light at approximately the same mean photon rate during our recordings. We therefore suggest that frontal photoreceptors attain a higher state of light adaptation for a given photon rate. This difference may be achieved by a higher density of (Ca2+ permeable) light-gated channels. Consistent with this hypothesis, membrane-impedance measurements show that frontal photoreceptors have a higher specific conductance than other photoreceptors. This higher conductance provides a better temporal performance but is metabolically expensive. Across the eye, temporal resolution is not proportional to spatial (optical) resolution. Neither is it matched obviously to optic flow. Instead we examine the consequences of an improved temporal resolution in the frontal region for the tracking of small moving targets, a behavior exhibited by male flies. We conclude that the temporal properties of a given class of retinal neuron can vary within a single retina and that this variation may be functionally related to the behavioral requirements of the animal.     

Intracellular staining of physiologically identified photoreceptor cells and hyperpolarizing interneurons in the teleost pineal organ

The directly photosensory pineal organ of the rainbow trout functions primarily as a luminance detector. Its neutral output reflects the level of ambient illumination in an almost linear fashion over several orders of magnitude. It may thus transmit information about the daily light-dark cycle to central projection targets in the brain, and exert an important control over putative central oscillators. We have studied single neural elements in the explanted pineal organ of the rainbow trout by combining intracellular recording with intracellular injections of either the fluorescent dye Lucifer Yellow CH or the electron dense marker horseradish peroxidase. After physiological characterization, dye was injected, and the pineal organs were processed for fluorescence or electron microscopy. Horseradish peroxidase-injected cells were selected with light microscopy, and were serially sectioned for electron microscopy. By examining the entire series of ultrathin sections of several labeled cells the following results were obtained. (1) Intensity-graded hyperpolarization that was elicited by light stimuli of all wavelengths could be either purely monophasic at all light intensities, or monophasic at low and intermediate light intensities but with an initial peak transient at response saturation. These two types of responses could be demonstrated to emanate from photoreceptor cells. (2) In addition, an interneuron that responded to light stimulation with intensity-graded hyperpolarizations that decreased in amplitude at high light intensities was identified by analysis of serial ultrathin sections. This interneuron was situated in close opposition to a photoreceptor-like element and another interneuron, both of which contained transcellularly transferred horseradish peroxidase. Transcellular transfer of horseradish peroxidase was repeatedly observed, although in the majority of cases only single cells were labeled. Intracellular injection of Lucifer Yellow CH consistently revealed dye-coupling between photoreceptors and between (inter)neurons. The numbers of labeled elements varied between two and eight cells, after intracellular injection of one cell. The present results indicate that the net neural output of the pineal organ is the result of a relatively complicated neural circuitry, encompassing different types of photoreceptors, interneurons and projection neurons. Electrical coupling between photoreceptors, between neurons, and between photoreceptors and neurons may provide spatial signal averaging. The very slow photoreceptor responses to photic stimulation may provide temporal signal averaging.(ABSTRACT TRUNCATED AT 400 WORDS)     

Cinobufagin exerts anti-proliferative and pro-apoptotic effects through the modulation ROS-mediated MAPKs signaling pathway

Abstract

Cinobufagin (CBG) is a cardiotoxic bufanolide steroid secreted by the skin and parotid venom glands of the Asiatic toad Bufo bufo gargarizans (called Chan-Su). Although CBG is known to exhibit anti-cancer activities, very little is known about its potential mechanism(s) of action. In this study, we investigated whether CBG mediates its effect through the modulation of the mitogen-activated protein kinases (MAPKs) signaling pathway in human multiple myeloma (MM) U266 cells. We found that CBG caused the significant activation of ERK, JNK and p38 MAPK in U266 cells. CBG showed much higher cytotoxicity against U266 cells as compared to peripheral blood mononuclear cells (PBMC). Induction of CBG increased reactive oxygen species (ROS) generation from mitochondria, which is associated with the induction of apoptosis as characterized by increased sub-G1 DNA contents of cell cycle, positive Annexin V binding, activation of caspase-3 and cleavage of PARP. Inhibition of ROS generation by N-acetyl-l-cysteine (NAC) significantly prevented CBG-induced ERK, JNK and p38 MAPK activation and apoptosis. CBG also down-regulated the expression of various downstream gene products that mediate cell proliferation, survival, angiogenesis and metastasis. Interestingly, ERK, JNK and p38MAPK pharmacological inhibitors blocked CBG-induced MAPKs activation and ERK inhibitor (PD98059) also prevented the CBG-induced caspase-3 activation and PARP cleavage in U266 cells. Taken together, these findings suggest that CBG can act as a potent anticancer agent against MM and possibly exerts its effects through the ROS-mediated activation of ERK, JNK and p38 MAPK leading to the activation of caspase-3 in U266 cells.     

Ionic relations and electrical properties of isolated oocytes of Bufo bufo with special reference to removal of extracellular chloride

1. The efflux rate coefficients of sodium, potassium and chloride from immature oocytes of the toad Bufo bufo have been measured and found to be respectively, 0.0069, 0.0023 and 0.0034 min(-1).2. Replacement of external chloride by sulphate resulted in a fall in chloride efflux of about 50%. This has been interpreted in terms of exchange diffusion.3. The membrane conductance has been measured and found to be 0.14 x 10(-3) mhos cm(-2) in good agreement with the value calculated from the flux data, 0.12 x 10(-3) mhos cm(-2), after taking account of the chloride exchange diffusion fraction.     

Active sodium transport by the colon of Bufo marinus: stimulation by aldosterone and antidiuretic hormone

1. The isolated colon of Bufo marinus transports sodium actively from the mucosal (lumen) to the serosal side, and this transport is expressed quantitatively by the short-circuit current.

2. Upon dilution of sodium in Ringer solution on the mucosal side of the preparation, short-circuit current remained a fair expression of sodium transport from mucosa to serosa.

3. In view of this, the relation between short-circuit current and dilution of sodium of the luminal side was examined. This relation was curvilinear, which suggests the intervention of a saturable step in the transfer of sodium from lumen to serosal surface of colon.

4. The relation between short-circuit current on the one hand, and the amount of sodium drawn from the luminal side and recovered in the membrane (`active sodium transport pool') on the other hand, appeared (almost) linear instead. This is meant to indicate that the `pump' operates far from capacity. Hence, the observed saturation of sodium transport, when concentration of sodium on the mucosal side was increased, probably occurs at the mucosal border of the preparation.

5. After treatment with aldosterone, the `active sodium transport pool' and short-circuit current increased to the same extent, from which it is inferred that the hormone merely allows sodium easier access to the `pump' which would react in proportion. Consequently, no direct influence of aldosterone on the `pump' proper need be postulated.

6. Upon exposure of the colon to antidiuretic hormone, there were (modest) increases of short-circuit current and of osmotic water flow across the wall of the organ.

     

Effects of telencephalic ablation on visual unit, sustained potential shift, and EEGs recorded from the toad tectum in response to a visual stimulus

Extracellular recordings were made of visual unit activity, sustained potential shifts (SPSs), and electroencephalographic activity (EEGs) from the optic tectum and of EEGs from the telencephalon of immobilized toads (Bufo bufo). Moving visual stimuli were presented, and the bioelectric responses were monitored both before and after ligature of the telencephalon. The operation reduced the neuronal spike frequency and the amplitude of the tectal SPS and EEG responses. EEGs were still recorded from the tectum and even the isolated telencephalon. The results are discussed in relation to possible adaptive functions of SPS and EEG changes, the genesis of the EEG, and the role of the telencephalon in visually guided prey-catching behavior.     

The influence of ACTH fragments on habituation of the prey catching behaviour in the European toad (Bufo bufo L.)

Earlier observations on the influence of the ACTH molecule on habituation in toads revealed a capacity, which resembles the improvement of learning and memory processes in rats [6]. In the present investigation ACTH, ACTH1-10 and ACTH11-24 were tested on habituation of turning reaction, a stereotypic component of the prey catching behaviour in the European Toad, Bufo bufo L.. Furthermore the time relationship of the ACTH-effect was determined by injections at different times prior to the beginning of the habituation. ACTH as well as ACTH1-10 caused a dramatic decline in turning reactions per minute towards a prey dummy, when administered 30 min prior to habituation. Therefore, the capacity to facilitate behavioral adaptations must be located mainly in the first ten amino acids of ACTH.