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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructure of the tentacles of the apodous holothurian Leptosynapta spp (Holothurioidea: Echinodermata) with special reference to the epidermis and surface coats (1988)
    Springer
    Cell & tissue research 251 (1988), S. 387-397 
    Details
    ISSN: 1432-0878
    Keywords: Tentacles ; Ultrastructure ; Adhesion ; Leptosynapta spp (Holotheorie) ; Echinodermata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tentacles of the apodous holothurian Genus Leptosynapta have been studied by use of transmission and scanning electron microscopy. The gross anatomy, water vascular system, fibre systems and ectoneural nerve ring are described. A fuzzy coat of attenuated filaments covers the surface of the tentacle, broken only by secretory ducts. A cuticle underlies the fuzzy coat. Bacteria are common in the subcuticular space. Fixation without osmium gives poor preservation of the surface coats. The epidermis consists of a single layer of columnar cells consisting of Type-1, Type-2, support, goblet and uniciliated cells. Type-1 cells secrete electron-dense material and appear to be homologous to adhesive cells of the tentacles of other holothurians. The support cells contain large, granular vesicles not found in other holothurians. Goblet cells contain flocculent mucus and have an apical cilium. Goblet cells are not found in other holothurian tentacles and may function to lubricate and wrap adhering particles to aid their ingestion. The uniciliated cells are rare, poorly developed and the cilium does not extend past the cuticle. The ultrastructure of the tentacles is discussed in relation to those of other holothurians.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215848
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  • 2
    Electronic Resource
    Electronic Resource
    The ultrastructure of the tentacles of eleven species of dendrochirote holothurians studied with special reference to the surface coats and papillae (1987)
    Springer
    Cell & tissue research 248 (1987), S. 187-199 
    Details
    ISSN: 1432-0878
    Keywords: Tentacles ; Ultrastructure ; Adhesion ; Echinodermata ; Dendrochirodita (11 species)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The tentacles of eleven species of dendrochirote holothurians have been studied. The water vascular system, deep fibre system, ectoneural nerve ring and superficial fibre system are described and are similar to those of other holothurian tentacles. A conspicuous fuzzy coat covers the entire tentacular surface except for the tips of cilia. On the basis of its structure it is thought to be an attenuated glycocalyx. Its function is discussed in relation to anti-fouling and surface adhesion. The two surface coats underlying the fuzzy coat are termed the cuticle. Bacteria are found both within the surface coats and in the sub-cuticular space. Primary fixatives lacking osmium give poor preservation of the surface coats. The adhesive papillae of the apices of the tentacles contain elements of support cells and two other cells named Type-1 and Type-2 papillar cells. The secretions of Type-1 papillar cells are dense-cored vesicles and may contain a proteinaceous adhesive. The vesicles fuse with the cuticle and release their products which are apparently disseminated along the fuzzy coat filaments. The secretions of Type-2 papillar cells may have a neurosecretory function. The different models of food capture by dendrochirote tentacles are discussed as are duo-glandular adhesive systems in relation to dendrochirote tentacles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01239980
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Modification of developmental instability and fitness: Malathion-resistance in the Australian sheep blowfly,Lucilia cuprina (1993)
    Springer
    Genetica 89 (1993), S. 67-76 
    Details
    ISSN: 1573-6857
    Keywords: Lucilia cuprina ; malathion-resistance ; fluctuating asymmetry ; fitness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution of resistance to malathion byLucilia cuprina initially results in an increase in fluctuating asymmetry. Resistant flies are at a selective disadvantage, relative to susceptibles, in the absence of the insecticide. A fitness/asymmetry modifier of diazinon-resistant phenotypes ameliorates these effects resulting in malathion-resistant phenotypes of relative fitness and asymmetry similar to susceptibles. For the nine genotypic combinations of the modifier and malathion-resistance alleles, developmental time increases linearly with increasing asymmetry. Percentage egg hatch decreases linearly with increasing asymmetry. The initially disruptive effect of the malathion-resistant allele was partially dominant, the effect of the modifier dominant. The results are discussed in terms of developmental perturbation, asymmetry estimation and relative fitness to consider whether it is adequate to use changes in fluctuating asymmetry alone as measures of developmental instability. It is suggested that in some circumstances antisymmetry may indicate developmental instability and that the diazinon/malathion-resistance systems inL. cuprina may allow the relative importance of genetical and/or environmental developmental perturbations to be ascertained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02424506
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  • 4
    Electronic Resource
    Electronic Resource
    Measuring fitness and intergenic interactions: The evolution of resistance to diazinon inLucilia cuprina (1993)
    Springer
    Genetica 90 (1993), S. 227-237 
    Details
    ISSN: 1573-6857
    Keywords: Lucilia cuprina ; diazinon resistance ; fitness ; asymmetry ; frequency-dependent selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Resistance at the diazinon-resistance locus (Rop-1) is recessive with respect to fitness. Selection initially occurs at concentrations lower than those required to controlLucilia cuprina. The presence of theRop-1 allele initially disrupted development so that in the absence of diazinon, carriers were at a relative selective disadvantage. Continued use of the chemical, subsequent to resistance evolving, selected a modifier to ameliorate this effect. Modified resistant phenotypes show similar developmental stability and relative fitness to susceptible individuals. Frequency-dependent interactions are observed between resistant and susceptible phenotypes of theRop-1 locus. The interactions are determined by the concentration of diazinon and range from competitive to facilitative. The results are discussed in the context of the contribution insecticide resistance systems can make to the study of general evolutionary phenomena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435042
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    Paper (German National Licenses)
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