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  • 1
    ISSN: 1432-072X
    Keywords: Methanogens ; Archaebacteria ; Autotrophic ; Thermophilic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An autotrophic thermophilic motile coccoid methanogen was isolated from geothermally heated sea sediments close to Naples, Italy. Growth occurs on H2/CO2 and on formate between 30 and 70°C with an optimum at 65°C. The optimal doubling time is only 55 min. The NaCl-concentration ranges from 1.3% to 8.3% with an optimum around 4%. By its G+C-content of 31.3 mol%, its subunit envelope, and by DNA-RNA hybridization the new isolate is clearly defined to be a member of the genusMethanococcus. We name itMethanococcus thermolithotrophicus.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Zoomorphology 91 (1978), S. 119-131 
    ISSN: 1432-234X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The antennal-tip sensory complex inAllacma fusca (Collembola) was reconstructed from serial ultrathin sections. The complex contains 16 sensory cells which belong to three spatially separated subunits: (1) a sensory hair; (2) a cuticular protrusion, containing two highly-specialized dendritic outer segments from a single sensory cell encapsulated by an enveloping cell and a gland cell (Figs. 4 and 5); and (3) two sensory cells with partly lamellated, double dendritic outer segments located well away from the cuticular surface (Fig. 3). A phylogenetic evaluation reveals a mosaic of apparently primitive characters, and trends toward higher structural complexity as well as toward reduction (Table 1). There is support for a hypothesis that the receptors of the sensory hair are chemosensitive. The functional interpretation of the other components of the complex is problematic due to their unusual structural properties. The sensory cell beneath the cuticular protrusion is considered to be proprioceptive.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 129 (1972), S. 196-216 
    ISSN: 1432-0878
    Keywords: Insect sensilla ; Stimulus conducting system ; Molt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. 1. Das Sinnesorgan des 3. Antennengliedes von Onychiurus sp. enthält 2 basiconische und 2 keulenförmige Sensillen mit je 3 bzw. 5 Sinneszellen. Die Oberfläche der Außenstrukturen der Sensillen ist wabenförmig. Vom Boden der Waben führen 50 Å weite Kanälchen über Porentubuli oder unmittelbar in den äußeren Rezeptorlymphraum. Auf dem 4. Antennenglied stehen Sensilla trichodea, die durch Poren und Porentubuli gekennzeichnet sind. 2. 2. Bei den Sensillen des Sinnesorganes des 3. wie bei den Sinneshaaren des 4. Antennengliedes liegt im Lymphraum über der trichogenen und tormogenen Zelle, in Spalträumen der Borsten- bzw. Keulenbasis, in äußeren Rezeptorlymphraum und bei den ersteren auch im Bereich der Porentubuli, Poren und Waben ein zusammenhängendes elektronendichtes Material, das durch H2O2 aus unkontrastierten Schnitten herausgelöst wird. Dieses Material, das von der tormogenen, vielleicht auch von der trichogenen Zelle sezerniert werden dürfte, wird als reizleitendes System interpretiert. 3. 3. Das Postantennalorgan stimmt hinsichtlich Porendurchmesser und Eigenschaften des reizleitenden Materials mit den antennalen Sensillen überein. 4. 4. Es werden 2 Häutungstypen unterschieden. Bei den antennalen Sensillen bleibt nach der Apolysis der strukturell unveränderte periphere Apparat über die verlängerten, umscheideten Dendriten mit dem proximalen Anteil unterhalb der Neubildung verbunden. Beim Postantennalorgan ziehen sich Dendriten und Hüllzelle bei der Apolysis aus den alten cuticulären Außenstrukturen zurück.
    Notes: Summary 1. 1. The sense organ on the third antennal segment of Onychiurus sp. consists of two basiconic and two club-shaped sensilla. Outwardly the cuticle of both types assumes the structure of a honeycomb with pores 50 Å wide perforating its floor. On the fourth antennal segment sensilla trichodea are found which are characterized by both pores and pore tubules. 2. 2. An electron-dense material within the fluid space across the trichogen and tormogen cells extends through canals in the base of the cuticular outer structures into the fluid space surrounding the outer dendritic segments. From here it continues into the pore tubules, out the pores and spreads across the floor of the combs, particularly in the sensilla of the sense organ on the third segment. The material can be extracted by H2O2 in uncontrasted sections. It is most probably secreted by the tormogen and trichogen cells. It may function as a stimulus conducting system. 3. 3. The postantennal organ has pores of the same size and a dense substance of the same properties as found in the antennal receptors. 4. 4. Two types of molt-related structural changes can be distinguished. As in other sensilla the dendrites and their cuticular sheathes in the antennal sensilla grow longer during the molt and maintain contact with the old outer structures until they are shed. In the postantennal organ on the other hand the dendrites break contact with the periphery at the onset of apolysis and withdraw together with their inner enveloping cell.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 182 (1977), S. 93-98 
    ISSN: 1432-0878
    Keywords: Statocyst ; Gravity receptor system ; Secondary sensory cells ; Octopus vulgaris (Cephalopoda)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The presence of secondary sensory cells in the Octopus gravity receptor system has been demonstrated. In serial thin sections of the receptor cells (hair cells) no axons were found leaving the cells. Instead, synapses were observed with synaptic vesicles lying inside the receptor cells. Both data clearly indicate that the receptor hair cells represent secondary sensory cells. In addition, efferent contacts to the receptor cells could be confirmed.
    Type of Medium: Electronic Resource
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