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Provider: - Institution: National Library of the Netherlands - Koninklijke Bibliotheek - Data provided by Europeana Collections- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Conditioning experiments revealed that Proteus perceives a back-and-forth moving (approximately 1 Hz) direct-current field and its polarity. Minimum behavioral thresholds occurred at a current ...density of 0.15 microA/cm2, corresponding to a voltage gradient of 0.5 mV/cm. Recordings from afferent nerve fibers showed that ampullary electroreceptors in Proteus respond as do other nonteleost receptors, i.e. with an increase in discharge rate to cathodal current and a decrease to anodal current (threshold: approximately 1 mV/cm).
Do the blind cave salamander Proteus and its epigean relative Necturus use the chemical sense in searching for prey? Proteus shows a significant, and Necturus only a weak, preference for water which ...passes living prey before entering a choice chamber. Prey which was frozen before the test also gave the same result in both species. However, with this immobilized prey the time for a decision in the test was much longer. The results of ten series of tests demonstrate the importance of chemoreception for prey detection in Proteus . The weaker reactions in Necturus can be explained probably by the different biotope. Six other series of tests have been conducted to show that these results are not influenced by stimuli relating to mechanoreception, thigmotaxis and rheotropism.
The multicellular epithelial organs in Proteus anguinus, which Bugnion (1873) assumed to be developing neuromasts, have been analyzed by light- and electron-microscopy. Their fundamental structure ...consists of single ampullae with sensory and accessory cells with apical parts that extend into the pit of the ampulla, and of a short jelly-filled canal connecting the ampulla pit with the surface of the skin. The organs are located intra-epithelially and are supported by a tiny dermal papilla. The cell elements of sensory epithelium are apically linked together by tight junctions. The free apical surface of the sensory cell bears several hundred densely packed stereocilia-like microvilli whereas the basal surface displays afferent neurosensory junctions with a pronounced round synaptic body. The compact uniform organization of the apical microvillous part shows a hexagonal pattern. A basal body was found in some sensory cells whereas a kinocilium was observed only in a single cell. The accessory cells have their free surface differentiated in a sparsely distributed and frequently-forked microvilli. The canal wall is built of two or three layers of tightly coalescent flat cells bordering on the lumen with branching microvilli. The ultrastructure of the content of the ampulla pit is presented. In the discussion stress is laid on the peculiarities of the natural history of Proteus anguinus that support the view that the morphologically-identified ampullary organs are electroreceptive. The structural characteristics of ampullary receptor cells are dealt with from the viewpoint of functional morphology and in the light of evolutionary hypotheses of ampullary organs.
In the perennibranchiate Proteus anguinus, larval myosin isoforms were shown to coexist for life with the adult isomyosins that appeared at the end of the larval stage. Analysis of the myofibrillar ...ATPase profile also revealed that a high percentage of immature fibers persisted in adults. A long-term treatment with large amounts of T3 had no effect on juvenile individuals. Applied to subadult animals it promoted a regression of larval myosin isoforms and a reduction in the percentage of immature fiber types. The regulative effect of T3 in the myosin isoenzymic transition may be delayed and depends on metabolic conditions, which suggests it is indirect.
