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  • 11
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 193 (1962), S. 750-752 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] THE nervous systems of insects and vertebrate animals are surrounded by cellular and fibrous sheaths which are generally supposed to represent effective diffusion barriers restricting the entry of ions and molecules into the underlying tissues1. In vertebrates both the peripheral nerves and the ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 55 (1982), S. 202-207 
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Field observations on the ocean skater, Halobates robustus Barber showed that the flotillas of adults, unlike those of juveniles, occurred very close to the shore at specific sites from which they were not easily dislodged. The adult flotillas consisted of small all-male groups or aggregations of males and copulating pairs. The proportion of free males in copulating flotillas decreased with increasing group size. There was no correlation between the sizes of the paired males and females. Single adult females, which were not observed in the copulating flotillas, were usually teneral with undeveloped eggs. In contrast, the copulating females contained numerous well-developed eggs. The pairs remained in prolonged genital contact. The behaviour of free males in copulating flotillas was characterized by frequent, non-random encounters with copulating pairs. Experiments with marked individuals established that male take-overs can occur within flotillas. It is concluded that the copulating flotillas are initiated by the males and not only provide protection from predators, as previously shown, but also act as arenas for mate finding and selection. It is presumed that prolonged copulation reduces sperm competition between contending males.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 181 (1958), S. 1280-1281 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Fig. 1. The effect of concentration on the movements of glucose labelled with carbon-14 between the mid-gut caeca and the naemo-lymph during an experimental period of 15-0 min. The open circles represent the percentage absorption of labelled glucose when the initial radioactivity of the glucose in ...
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 211 (1966), S. 215-216 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] In an insect such as the cockroach, the deposits of closely adhering fat-body cells are confined as small patches on the surface of ganglia and are absent from the inter-ganglionic connectives. Recent investigation has shown that in the stick insect (Carausius morosus), however, the fat-body cells ...
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 223 (1969), S. 377-380 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The sodium which is available to maintain the activity of the large axons of Anodonta cygnea (Mollusca: Eulamellibranchia) seems to be in two forms. One is immediately accessible; the other is a store that can be mobilized to sustain axonal ...
    Materialart: Digitale Medien
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  • 16
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary On a marine saltmarsh, the intertidal mite, Bdella interrupta Evans, is exposed to periods of regular tidal submergence which alternate with periods of tidal emergence. The mite shows well defined day and night peaks of locomotory activity on the soil surface. During periods of tidal submergence the activity peaks showed an apparent periodicity, of around 12.5 h, characteristic of a tidal rhythm. In the presence of non-submerging tides the periodicity of the activity peaks changed to around 11.5 h. It is suggested that this shorter periodicity results either from free-running of the circatidal clock in the absence of entraining tides or from a sequence of transients that are phaseshifting towards a stable relationship with a second zeitgeber. It is further suggested that the alternation between a ca. 12.5 h and a ca. 11.5 h rhythm ensures that an activity peak is maintained in daylight and, also, reduces the possibility of inundation during the first critical floodings during sequences of rising spring tides.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 21 (1975), S. 141-155 
    ISSN: 1432-1939
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The intertidal aphid, Pemphigus trehernei, is restricted to aster plants (Aster tripolium) growing near the edges of creeks and salt pans in low areas on tidal saltmarshes. Aphid populations in mid-marsh areas do not show an equivalent edge effect. In low-marshes the edge soil generally has more surface cracks and cavities which can accommodate aphids and a higher % air space than soil from regions away from edges. Adults and 1st instars can penetrate edge soil more readily than non-edge soil. Aphid abundance is positively correlated with % air space in low-marsh regions. Aphid populations established on potted asters were destroyed or reduced to very low levels when transferred to non-edge regions of low-marsh areas. It is suggested that aphid distribution is primarily limited by soil conditions, especially the extent of soil drainage.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 247 (1987), S. 111-120 
    ISSN: 1432-0878
    Schlagwort(e): Glia ; Neural repair ; CNS ; Organ culture ; Insect, Periplaneta americana
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Insect glial cells are capable of division and repair in organ culture after selective damage with the toxin ethidium bromide. The repair is slower and less organised than seen in vivo after similar treatment and is still incomplete after one month. Granule-containing cells, which play an important role in the early stages of repair in vivo, are never seen in cultured connectives. This observation adds further support to the hypothesis that these cells are derived from haemocytes and that their presence is necessary for rapid and orderly repair. The uptake of 3H-thymidine into perineurial glial cells in vitro, both in control and ethidiumtreated connectives, shows that there is a considerable proliferation of cells in this region. Some uptake of thymidine is also seen in subperineurial glia but division alone cannot account for the large increase in the number of glial nuclei found at the early stages of repair in this region. Further, glial cells with diverse morphologies suggest that subpopulations are present. We conclude that cell migration from undamaged areas, as well as cell proliferation, is necessary for CNS repair in vitro.
    Materialart: Digitale Medien
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  • 19
    ISSN: 1432-0878
    Schlagwort(e): Haemocytes ; Glia ; Central nervous system ; Repair ; Insect ; Periplaneta americana
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Injection of physiologically inert particles (fluorescent microspheres) has a profound effect on neural repair of central nervous connectives of the cockroach Periplaneta americana following selective glial disruption. The injected particles, which do not gain direct access to the central nervous tissues, are taken up by a relatively small proportion (〈 10%) of the haemocytes. This interference with haemocyte function virtually abolishes the appearance of the granule-containing cells (which are prominently involved in normal glial repair) and produces abnormal reorganization of the superficial glial elements. These results are interpreted as evidence that the granule-containing cells are derived from haemocytes which are critically involved in glial repair.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    Cell & tissue research 243 (1986), S. 375-384 
    ISSN: 1432-0878
    Schlagwort(e): Glia ; Haemocyte ; Central nervous system ; Bleomycin ; Neural repair ; Insect, Periplaneta americana
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The DNA-binding drug, bleomycin, has a profound effect on neural repair following selective glial disruption by ethidium bromide. The contribution of the granule-containing cells (which normally appear in the early stages of repair) is greatly reduced, the restoration of the blood-brain barrier is delayed and the ultrastructural organization of the reorganising perineurium is dramatically changed. The aberrant perineurial structure and function observed in the presence of bleomycin are postulated to result from the effects of the drug on haemocytes which, together with endogenous reactive cells, contribute to the normal process of glial repair.
    Materialart: Digitale Medien
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