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741.
742.
Summary A new bathypelagic species of the genus Heterokrohnia, H. longicaudata, is described and separated from the other five previously described Heterokrohnia species, H. mirabilis Ritter-Záhony 1911, H. bathybia Marumo and Kitou 1966, H. involucrum Dawson 1968, H. longidentata Kapp and Hagen 1985 and H. fragilis Kapp and Hagen 1985. The new specimen has been found at great depths (2,350m–1,000m) near Elephant Island, in the atlantic sector north of the Antarctic Peninsula. 相似文献
743.
Helga I. Georgescu Deanna Mendelow Christopher H. Evans 《In vitro cellular & developmental biology. Plant》1988,24(10):1015-1022
Summary We have isolated a continuous cell line from soft tissue lining the knee joints of rabbits. Designated HIG-82, this line was
produced by spontaneous establishment of an aging, late-passage culture of primary cells. Like unpassaged, primary cells,
HIG-82 cells can be activated by a number of stimuli, including phorbol myristate acetate (PMA), interleukin-1 (IL-1), and
the endocytosis of latex beads. Activated cells secrete collagenase, gelatinase, caseinase (stromelysin), and prostaglandin
E2 (PGE2) into their culture medium. Pseudodiploid, HIG-82 cells combine a high plating efficiency with a doubling time of approximately
24 h. As primary tissue of this origin is difficult to obtain in large quantities and shows cellular heterogeneity, the HIG-82
cell line should facilitate research into the biology and biochemistry of the fibroblastic cells that line the diarthrodial
joints of mammals. Such cells are likely to be important in the pathophysiology of various arthritides.
This work was supported, in part, by the Veteran's Administration, Washington, DC, and by grants AR36891 and AM07552 from
the National Institutes of Health, Bethesda, MD. 相似文献
744.
Piotr Golinski Stanisĺaw Wnuk Maĺgorzata Manka Peter Lepom Helga Kloss 《Mycotoxin Research》1987,3(1):46-48
Twelve isolates ofFusarium avenaceum Fries Sacc. originating from diseased corn plants from Germany produced Avenacein Y in amounts ranging from 0.001 to 1.6 g/kg of wheat grain. The isolates proved most pathogenic to triticale seedlings, less pathogenic to rye seedlings and least to wheat. Pathogenicity of the isolates was not correlated with their ability to produce Avenacein Y. 相似文献
745.
1. An improved method for the purification of Clostridium perfringens polynucleotide phosphorylase (nucleoside diphosphate-polyribonucleotide nucleotidyltransferase, EC 2.7.7.8) is described. The product was stable and was highly stimulated by polylysine or polyornithine. 2. It migrated as a single enzyme during sucrose-density-gradient centrifugation, and no separation of polymerization and phosphorolytic activities was observed. 3. Trypsin digestion caused a rapid, preferential loss of the polylysine- or polyornithine-stimulated activity, which was prevented by low concentrations of polyornithine. 4. The protection by polyornithine was not specific. 5. It is concluded that charge effects on the clostridial polynucleotide phosphorylase itself are primarily responsible for the stimulation of this enzyme by polylysine or polyornithine. 相似文献
746.
Zusammenfassung In der Wand der Eminentia mediana des Kaninchens kommen Plasmazellen vor. Jede von ihnen ist umgeben von einem wechselnd weiten perizellulären Spalt, von markscheidenführenden und markscheidenfreien Axonen und von Glia- und Ependymfortsätzen. Eine Basalmembran zwischen Plasmazellen und Ependym fehlt. Plasmazellen werden auch im perivaskulären Spalt und im Ventrikellumen des Recessus infundibuli gefunden.
Plasma cells in the wall of the median eminence in rabbit
Summary In the wall of the median eminence (rabbit) plasma cells occur. Each of them is surrounded by a variable pericellular space, by nonmyelinated and myelinated axons and by glial and ependymal processes. A basement membrane between the ependyma and the plasma cells does not exist. Plasma cells also are to be found in the perivascular space and in the cavity of the recessus infundibuli.
Die Untersuchung wurde mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft durchgeführt. 相似文献
747.
Helga Dahlhelm 《Planta》1969,86(3):224-234
Summary The auxin-induced cell elongation and the formation of indoleacetyl-aspartic acid (IAAsp) of pea epicotyl sections and Agrostemma hypocotyl sections are inhibited by heavy water. The formation of IAAsp requires a specific enzyme. The lack of IAAsp in D2O-treated plant tissues may be due to an influence of D2O on the induction or on the synthesis of that enzyme. Treatment of plant sections with synthetic IAAsp has no effect on the growth of the sections in D2O. Indole-3-acetic acid (IAA) increases the incorporation of 32P-orthophosphate into ribosomal and soluble RNA of pea epicotyl sections in H2O but not in D2O. The synthesis of ribosomal RNA is decreased by heavy water.The effects of IAA and D2O on the soluble proteins of pea sections have been studied by PAA-gel electrophoresis. D2O does not change the pattern of protein bands in comparison with the H2O-control, but prevents the probably IAA-induced alteration of the Rf-value of one protein band on the pherogram. It is assumed that the inhibition of auxin-induced reactions in the D2O-medium is due to the stabilizing effect of heavy water on allosteric proteins. The results of this work support the hypothesis that IAA acts as allosteric effector. 相似文献
748.
Summary Intracellular phenylalanine and tyrosine was determined in lymphocytes of 19 heterozygotes (parents) for PKU and in 26 randomly collected apparently normal persons. In cells from the heterozygotes the concentrations of both phenylalanine and tyrosine were higher than in those from the normals, the difference being statistically highly significant. It is argued that this could be responsible for the slight, though statistically significant, intellectual inferiority of heterozygotes for PKU. 相似文献
749.
Zusammenfassung Durch drei verschiedene Methoden wurde in Kulturen vonAcanthamoeba castellanii die stationäre Wachstumsphase, in deren Verlauf sich Trophozoiten zu Cysten entwickeln, induziert: Durch Nahrungsmangel, indem Amöben der logarithmischen Wachstumsphase in ein nährstofffreies Medium überführt wurden, durch Sauerstoffmangel, indem Kulturen zu großer Zelldichte heranwuchsen, und durch Hemmung der mitochondrialen DNS-Synthese, indem Kulturen der logarithmischen Phase mit Äthidiumbromid versetzt wurden.Unabhängig von den Encystierungsbedingungen nimmt die intracelluläre Konzentration von Adenosin-3,5-monophosphat (cAMP) bei Verminderung der Zellteilungsrate bis zu Beginn der stationären Wachstumsphase um das 2–3 fache zu. Die Ergebnisse deuten an, daß der Anstieg von intracellulärem cAMP auf eine Erhöhung der Adenylat-Cyclase- und nicht auf eine Verminderung der Phosphodiesterase-Aktivität zurückzuführen ist.Extracelluläres cAMP konnte weder in Kulturen der logarithmischen noch in Kulturen der stationären Phase nachgewiesen werden. Dies ist vermutlich auf die extracellulär vorhandene cAMP-Phosphodiesterase zurückzuführen.Die Tatsache, daß auch durch Theophyllin die stationäre Wachstumsphase und Encystierung induziert werden kann, läßt auf eine Beteiligung von cAMP an den Entwicklungsprozessen, speziell an dem Abbau von Glykogen, schließen.
The role of adenosine-3,5-monophosphate in the development ofAcanthamoeba castellanii
In cultures ofacanthamoeba castellanii the stationary growth phase in which trophozoites develop to cysts, was induced in three ways: by transferring cells from a logarithmic growing culture into a nutrient-free medium, by growth in nutrient medium to high cell density and by inhibition of the mitochondrial DNA synthesis with ethidium bromide.In all cases, the intracellular concentration of adenosine-3,5-monophosphate (cAMP) rises by a factor of two to three from the end of the logarithmic phase to the beginning of the stationary phase. The results show that this rise may be more a consequence of an increased adenylate cyclase activity than of a diminished cAMP phosphodiesterase activity.No extracellular cAMP could be measured in cultures of the logarithmic and stationary growth phase, perhaps because of the extracellular cAMP phosphodiesterase.Because theophylline also induces the stationary phase and encystation, cAMP seems to be of importance for the development ofAcanthamoeba castellanii, especially for the degradation of glycogen.相似文献
750.
Summary The NADH-nitrate oxidoreductase of Chlorella vulgaris has an inactive form which has previously been shown to be a cyanide complex of the reduced enzyme. This inactive enzyme can be reactivated by treatment with ferricyanide in vitro. In the present study, the activation state of the enzyme was determined after different prior in vivo programs involving environmental variations. Oxygen, nitrate, light and CO2 all affect the in vivo inactivation of the enzyme in an interdependent manner. In general, the inactivation is stimulated by O2 and inhibited by nitrate and CO2. Light may stimulate or inhibit, depending on conditions. Thus, the effects of CO2 and nitrate (inhibition of reversible inactivation) are clearly manifested only in the light. In contrast, light stimulates the inactivation in the presence of oxygen and the absence of CO2 and nitrate. Since the inactivation of the enzyme requires HCN and NADH, and it is improbable that O2 stimulates NADH formation, it is reasonable to conclude that HCN is formed as the result of an oxidation reaction (which is stimulated by light). The formation of HCN is probably stimulated by Mn2+, since the formation of reversibly-inactivated enzyme is impaired in Mn2+-deficient cells. The prevention of enzyme inactivation by nitrate in vivo is in keeping with previous in vitro results showing that nitrate prevents inactivation by maintaining the enzyme in the oxidized form. A stimulation of nitrate uptake by CO2 and light could account for the effect of CO2 (prevention of inactivation) which is seen mainly in the presence of nitrate and light. Ammonia added in the presence of nitrate has the same effect on the enzyme as removing nitrate (promotion of reversible inactivation). Ammonia added in the absence of nitrate has little extra effect. It is therefore likely that ammonia acts by preventing nitrate uptake. The uncoupler, carbonylcyanide-m-chloro-phenylhydrazone, causes enzyme inactivation because it acts as a good HCN precursor, particularly in the light. Nitrite, arsenate and dinitrophenol cause an enzyme inactivation which can not be reversed by ferricyanide in crude extracts. This suggests that there are at least two different ways in which the enzyme can be inactivated rather rapidly in vivo. 相似文献