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111.
Distribution of sulfated mucopolysaccharides in invertebrates.   总被引:13,自引:0,他引:13  
The sulfated mucopolysaccharide composition of 22 species of invertebrates belonging to the phyla Arthropoda, Mollusca, Annelida, Tunicata, Echinodermata, Coelenterata, and Porifera was analyzed. It is shown that all the species contain variable amounts of one or more types of sulfated mocopolysaccharides, most of which similar to the ones found in vertebrates. It is shown also that each species has a characteristic composition, differing from each other regarding the relative amount and type of chondroitin sulfates A, B, and C, heparitin sulfate, and heparin. The possible biological role of the sulfated mucopolysaccharides in cell recognition or aggregation or both is discussed in view of the present findings.  相似文献   
112.
The distribution of sulfated mucopolysaccharides in different tissues during growth and in cancer tissues is reported. It is shown that most of the tissues of 1 day-old rats and rabbits contain chondroitin sulfate A/C, chondroitin sulfate B and heparan sulfate in about the same proportions, whereas in adult animals chondroitin sulfate A/C decreases in concentration or disappears. Changes in the relative proportions of chondroitin sulfate B and heparan sulfate were also observed in most of the tissues. In rats, these changes occur in the first 25 days of extrauterine development. A great increase of chondroitin sulfate A/C was observed in human tumors of different origins when compared with the normal adjacent tissues. Changes in the relative proportions of chondroitin sulfate B and heparan sulfate were also observed in most of the tumors analysed. The possible role of chondroitin sulfate A/C in cell division is discussed in view of the present findings.  相似文献   
113.
    
Zusammenfassung Bei Haustauben, die in einem horizontalen Windkanal mit 48 km/h stationär flogen, wurden mit Hilfe von Zeitlupenanalysen Schlagphasen nachgewiesen, die dem vonWeis-Fogh (1973) geforderten clap-and-fling Mechanismus entsprechen. Am Ende des Aufschlags schlagen die beiden Flügel mit der morphologischen Oberseite ± vollständig zusammen (clap). Vor dem Abschlag öffnen sie sich wie die Seiten eines Buches von vorn nach hinten (fling); erst am Ende dieser Phase entfernen sie sich voneinander. Weitere feinkinematische Ergebnisse werden mitgeteilt. Diese instationären Schlagphasen werden insbesondere dann eingesetzt, wenn hohe Luftkräfte benötigt werden. Die Kinematik der Flügelbewegung ist demnach so beschaffen, daß durch frühzeitige Zirkulationsinduzierung bereits ganz zu Beginn des Abschlags hohe Auftriebskräfte erzeugt werden könnten. Es wird diskutiert, daß der clap-and-fling Mechanismus auch für rasche Beschleunigungen bei hohem Schubbedarf eingesetzt werden könnte.
Evidence for a clap-and-fling mechanism in pigeons flying in a windtunnel
Summary Slow motion pictures of pigeons flying horizontally at a speed of 48 km/h in a windtunnel have shown flight patterns which seemed to be similar to the clap-and-fling mechanism discribed byWeis-Fogh (1973) for small insects. At the end of upstroke, both upper surfaces of the wings come together ± completely (clap). Before downstroke, the wings are opened like the pages of a book (fling). This instationary wingbeat pattern is used especially when high aerodynamic forces are needed. The clap-and-fling mechanism enables the bird to establish an early circulation so that, at the very beginning of downstroke, high lift forces can be produced. The question whether the clap-and-fling mechanism is also used for quick accelerations when greater thrust is required is also discussed.


Mit Geräteunterstützung durch die Deutsche Forschungsgemeinschaft  相似文献   
114.
Zusammenfassung Der Bruterfolg des Eleonorenfalken wurde auf einer ägäischen Inselkolonie in Relation zur Horstlage untersucht. Bei Horsten mit Gratlage auf übersichtlichem Gelände war er signifikant höher (1,8 Junge/Horst) als bei den übrigen Horsten mit z. T. schlechtem Geländeüberblick (1,3 Junge/Horst). Da alle Horste gegenüber den NW-Winden geschützt lagen, waren die meisten an südlich ausgerichteten Hängen potentiell der intensiven Sonneneinstrahlung ausgesetzt. In den Horstrevieren von typisch 20 m Durchmesser gab es aber nicht immer vor Sonne geschützte Horsthöhlen, so daß bei Lufttemperaturen von 40 °C und Bodentemperaturen von bis zu 60 °C die Embryonen in den Eiern gefährdet sein können, besonders, wenn sie der direkten Sonneneinstrahlung ausgesetzt sind. Dies tritt z. B. bei einer Störung in der Brutkolonie ein. Der Bruterfolg in den sonnenexponierten Höhlen lag mit 0,8–1,3 Junge/Horst signifikant niedriger als in den sonnengeschützten Höhlen mit durchschnittlich 1,75 Junge/Horst. Neben einer normalen Infertilität von 10 % fielen weitere 8 % aller Eier in der Brutkolonie durch Sonneneinwirkung aus.
Biology of the Eleonora's Falcon(Falco eleonorae): 10. Breeding success in relation to nest site exposition
Summary Breeding success of the Eleonora's Falcon was studied in an Aegean island colony. In nests near cliff tops with an unobstructed view of the surroundings, a significantly higher breeding success (1.8 pulli/nest) was obtained than in other nests (1.3 pulli/nest). Since all nests were chosen protected from the wind, and as the main wind comes from NW, most nests were situated on southern slopes and are thus potentially exposed to the sun. Within a falcon territory of typically 20 m diameter in size there was not always a lime stone crevice with complete shade for the eggs. At an air temperature of 40 °C and a soil temperature of up to 60 °C, excessive sunning of an unprotected egg can be lethal for the falcon embryo. Breeding success in sun exposed nests was significantly lower (0.8–1.3 pulli/nest) than in sheltered nests (1.75 pulli/nest). In addition to a normal infertility of 10 %, about 8 % of all eggs laid were lost due to sun irradiation.
  相似文献   
115.
Zusammenfassung An 1047 Silbermöwen-Nestern auf den Watteninseln Mellum und Memmert wurden 1979/80 ermittelt (Abb. 1): Grenzrichtungen der Vegetationsstände 1–3 (1: Vegetationsstand größter Winkelgröße) und Nest-Zugänge 1–3, ihre Winkelgrößen und mittleren Richtungen. Mehr als 80% der Nester waren zu 40–90% von Vegetation umstanden (Abb. 2). Die Winkelgröße des Gesamtvegetationsstandes betrug auf Mellum 212°, auf Memmert 205° (Tab. 1). Die Nestzugänge hatten eine geringere Winkelgröße als die Vegetationsstände (Tab. 1, Abb. 3). Die Silbermöwe bevorzugte demnach Nestplätze, die von Vegetation schützend umgeben sind. Der Vegetationsstand 1 befand sich bevorzugt auf der westlichen (= Hauptwindrichtung), der Zugang 1 auf der östlichen Nestseite (Tab. 2, Abb. 4). Die Verteilung der Gesamtvegetation zeigte entsprechende Vorzugsrichtungen (Abb. 6). Im Vergleich zu 1979 war 1980 eine Verlagerung der Vorzugsrichtung des Vegetationsstandes 1 um 50–60° von West nach Nord festzustellen (Tab. 2, Abb. 4). Ein Vergleich der mittleren Windrichtungen beider Jahre zeigte eine gleichsinnige Richtungsänderung (Abb. 5). Auf den zwei untersuchten Probeflächen Mellums ließ sich eine Auswahl des Nestplatzes im Hinblick auf Sichtschutz gegen Nachbarn nicht nachweisen (Tab. 3). Die mögliche Funktion der nestumgebenden Vegetation als Wind- und Wetterschutz wird diskutiert.
Vegetation surrounding Herring Gulls'(Larus argentatus) nests in relation to wind direction
Summary The following measurements were taken for a total of 1047 Herring Gulls' nests on the North Sea islands Mellum and Memmert (West Germany) in 1979 and 1980 (cf. Fig. 1 for terminology): limiting directions, angular sizes, and mean directions of the surrounding vegetation-stands 1 to 3 (1 = vegetation-stand with largest angular size), and of the entrances 1 to 3. For more than 80% of the nests, 40–90% of the circumference were surrounded by vegetation (Fig. 2). The mean angular size of the total vegetation-stand was 212° on Mellum and 205° on Memmert (Tab. 1). The nest entrances had a smaller angular size than the vegetation-stands (Tab. 1, Fig. 3). This shows the Herring Gull's preference for nest sites protected by surrounding vegetation.Vegetation-stand 1 was preferably orientated towards the west (= main wind direction), nest entrance 1 towards the east (Tab. 2, Fig. 4). The distribution of the total vegetation showed corresponding preferred directions (Fig. 6). A comparison of the years 1979 and 1980 revealed a shift of 50°–60°, from west to north, for the preferred direction of vegetation-stand 1 (Tab. 2, Fig. 4). A similar shift could be found for the mean wind direction (Fig. 5). For the two study plots on Mellum, a nest site selection favouring visual isolation from neighbours' nests could not be demonstrated (Tab. 3). The possible function of nest-surrounding vegetation as a shelter against wind and weather is discussed.


Herrn Dr. Friedrich Goethe zur Vollendung des 70. Lebensjahres gewidmet  相似文献   
116.
Abstract— In cell cultures of glial character derived from perinatal mouse brain adenosine elicits two effects. (a) At submicromolar concentrations It inhibits the increase in the intracellular level of cyclic AMP caused by β-adrenoceptor agonists. (b) At concentrations above micromolar it increases the level of cyclic AMP in the cultures. These two effects are mediated by two different adenosine receptors present on the outer surface of the cells. This is concluded from the following evidence. (a) Both effects are antagonized by methylxanthines but not by blockage of adenosine uptake or inhibition of phosphodiesterase activity. (b) In both cases activity depends on the integrity of the ribose moiety of the nucleotide. Substituents of the purine system are tolerated comparatively well. (c) The order of potency of adenosine analogues is different for the two effects. We suggest the name A1 receptors for those that mediate the inhibition and A2 for those that mediate the stimulation of cyclic AMP accumulation.  相似文献   
117.
Over 70 naturally occurring and synthetic flavonoids were screened for mutagenicity with 5 tester strains in the Salmonella/mammalian microsome assay: TA1535, TA100, TA1537, TA1538 and TA98. Frameshift mutagenicity was confined to the flavonols (flavon-3-ols) in strain TA98, TA1537 and TA100. The two most mutagenic falvonols, namely, quercetin (3,3',4',5,7-pentahydroxyflavone) and kaempferol (3,4',5,7-tetrahydroxyflavone), exhibiting 12 and 7 revertants/nmol in TA98 respectively, are also the most common flavonols occurring in plants. Other flavonols exhibited less activity (revertants/nmol): galangin (2.0), rhamnetin (0.45), kaempferide (0.24), fisetin (0.14), myricetin (0.12), robinetin (0.06) and morin (0.05). All of these flavonols apparently exhibited significant activation by Aroclor 1254 induced rat-liver microsome preparations (S9). However, subsequent study revealed that only those flavonols either lacking or possessing one B ring hydroxyl group had an absolute requirement for microsomal activation. Alternatively, quercetin with two B-ring OH groups is not activated by microsomal enzymes, but by soluble (S100) enzymes from liver which are apparently constitutive and not subject to the usual chemical induction. 3 flavonol glycosides, namely, quercetrin (quercetin-3-O-rhamnoside), rutin (quercetin-3-O-rutinoside) and robinin (kaempferol-3-O-galactosido-rhamnoside-7-O-rhamnoside), were found to be nonmutagenic. They could, however, be activated by a variety of mixed glycosidases incorporated in the usual pour plate procedure. The most effective enzyme mixtures were obtained from rat cecal bacteria and from the snail Helix pomatia.  相似文献   
118.
Summary The connections of the olfactory bulb were studied in the piranha using the Nauta and horseradish-peroxidase methods. Three olfactory tracts project to seven terminal fields in the telencephalon and one in the diencephalon, all of them bilaterally. The contralateral olfactory bulb also receives a small input. All contralateral projections decussate in the anterior commissure and are relatively weak compared to the ipsilateral projections. HRP-containing cells were found in all of the ipsilateral telencephalic aggregates receiving an olfactory tract projection; the contralateral side was free of labeled cell bodies. Although only about one fourth of the entire telencephalon receives a direct olfactory input, the high degree of differentiation of the olfactory system suggests that the piranha depends substantially on the sense of olfaction and that this species may be a good model for further studies on olfactory mechanisms.  相似文献   
119.
120.
The utilization of ortho-phosphate by two coastal marine diatomspecies, Nitzschia closterium and Cyclotella cryptica, was studiedin batch cultures. The hypothesis was tested that thresholdconcentrations in the phosphate uptake determine the lower limitof environmental phosphate, permitting the existence of species.The turn-over time of residual medium phosphate in culturesis {small tilde}10 min, indicating a rapid equilibration ofconcentration dependent on uptake with leakage of ortho-phosphate.Increasing phosphate starvation in cultures diminished the residualortho-phosphate in the range of {small tilde}60–<2nmol l–1, as measured radiochemically after elution onSephadex® G-10 gel. These concentrations encompass the rangeof limiting phosphate concentration in continuous cultures ofthe few microalgae, for which these concentrations are actuallymeasured. The diatoms excreted {small tilde}20–100 nmolI–1 of organic phosphate. One dominating compound, probablyan unusual nucleotide, was incompletely or not resorbed underphosphate starvation. In contrast, Nitzschia closterium excretedunder ample phosphate supply a series of three related compounds,probably phospholipids, that were resorbed under depletion.The association of the organic phosphates with macromolecularexudates is interpreted, along with the other observations,as an indication for a hardly explored periplasmatic phosphatemetabolism in these algae. 3Dedicated to Prof. Dr. H.-A. von Stosch in honour of his 75thbirthday. 4This study was conducted at the University of Marburg undersupport of the Humboldt Foundation Publication no. 64 of theproject "Biological Research of the Eems-Dollard Estuary".  相似文献   
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