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1.
Gisela Drews Kai Graszynski 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1987,157(3):345-353
Summary Euryhaline Crustacea living in dilute media, counterbalance the salt loss by active absorption of NaCl across the gill epithelium. To investigate the mechanisms involved in salt absorption, transeptithelial potential difference (PDte) was measured in isolated, perfused gills of the fiddler crab,Uca tangeri. The influence of some specific inhibitors of epithelial ion transport on the PDte was tested.With symmetrical conditions on both sides of the epithelium, the posterior gills ofUca tangeri showed a spontaneous PDte of +5 to +10 mV, that is an active transport potential which was positive on the bath side as referred to the hemolymph side. This potential decreased considerably after application of KCN or 2,4-dinitrophenol (DNP) to the perfusion saline.Omission of K+ from the perfusion saline or addition of ouabain led to a reversible drop of the PDte, suggesting that the absorption of Na+ and also of Cl– is driven by the (Na++K+)ATPase located in the basolateral membrane of the epithelial cells.Perfusion of the hemolymph space with saline containing diphenylamine-2-carboxylate (DPC) or the loop diuretic furosemide resulted in a decrease of the PDte.After application of amiloride to the bath saline the PDte increased. Half-maximum response to amiloride was reached at a concentration of about 10–5 mol·l–1. This suggests that one of the Na+ pathways across the apical membrane may consist of Na+ channels.Abbreviations
PD
te
transepithelial potential difference
-
DPC
diphenylamine-2-carboxylate
-
R
ps
resistance of perfusate shunt
-
R
te
transepithelial resistance
-
R
in
input resistance
-
DNP
2,4-dinitrophenol
Parts of this study have been reported at the 1st Congress of Comparative Physiology and Biochemistry, Liège 1984, and at the Vth European Colloquium on Renal Physiology, Frankfurt, 1985 相似文献
2.
A monozygotic twin pair with Rett syndrome 总被引:1,自引:1,他引:0
Summary A five-year-old, monozygotic, Turkish female twin pair with Rett syndrome is described. The twins are almost completely concordant in all clinical signs. This observation suggests a genetic cause of Rett syndrome. 相似文献
3.
The role of kinesin and other soluble factors in organelle movement along microtubules 总被引:32,自引:17,他引:15
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Kinesin is a force-generating ATPase that drives the sliding movement of microtubules on glass coverslips and the movement of plastic beads along microtubules. Although kinesin is suspected to participate in microtubule-based organelle transport, the exact role it plays in this process is unclear. To address this question, we have developed a quantitative assay that allows us to determine the ability of soluble factors to promote organelle movement. Salt-washed organelles from squid axoplasm exhibited a nearly undetectable level of movement on purified microtubules. Their frequency of movement could be increased greater than 20-fold by the addition of a high speed axoplasmic supernatant. Immunoadsorption of kinesin from this supernatant decreased the frequency of organelle movement by more than 70%; organelle movements in both directions were markedly reduced. Surprisingly, antibody purified kinesin did not promote organelle movement either by itself or when it was added back to the kinesin-depleted supernatant. This result suggested that other soluble factors necessary for organelle movement were removed along with kinesin during immunoadsorption of the supernatant. A high level of organelle motor activity was recovered in a high salt eluate of the immunoadsorbent that contained only little kinesin. On the basis of these results we propose that organelle movement on microtubules involves other soluble axoplasmic factors in addition to kinesin. 相似文献
4.
Dr. Gisela Baumann R. Theiler-Hedtrich Prof. Dr. R. Casper 《Journal of Phytopathology》1988,122(4):372-375
Apple mosaic virus and raspberry bushy dwarf virus were detected by ELISA in plantlets of red raspberry still growing in vitro. The plantlets were derived from explants which were excised from plants infected by either of the viruses mentioned. Detection by ELISA of prune dwarf virus in 4-month-old in vitro cultures of sour cherry was reported earlier. Thus, application of ELISA to tissue cultured plants in vitro seems to be an appropriate method for early detection of virus-infected plant cultures. 相似文献
5.
High intensity and blue light regulated expression of chimeric chalcone synthase genes in transgenic Arabidopsis thaliana plants 总被引:10,自引:0,他引:10
Rhonda L. Feinbaum Gisela Storz Frederick M. Ausubel 《Molecular & general genetics : MGG》1991,226(3):449-456
Summary To establish a genetic system for dissection of light-mediated signal transduction in plants, we analyzed the light wavelengths and promoter sequences responsible for the light-induced expression of the Arabidopsis thaliana chalcone synthase (CHS) promoter fused to the -glucuronidase (GUS) marker gene. Transgenic A. thaliana lines carrying 1975, 523, 186, and 17 by of the CHS promoter fused to the GUS gene were generated, and the expression of these chimeric genes was monitored in response to high intensity light in mature plants and to different wavelengths of light in seedlings. Fusion constructs containing 1975 and 523 by of CHS promoter sequence behaved identically to the endogenous CHS gene under all conditions. Expression of these constructs was induced specifically in response to high intensity white light and blue light. The response to blue light was seen in the presence of the Pfr form of phytochrome. Fusion constructs containing 186 by of promoter sequence showed reduced basal levels of expression and only weak stimulation by blue light but were induced significantly by high intensity white light. These analyses showed that the expression of the A. thaliana CHS gene is responsive to a specific blue light receptor and that sequences between — 523 and — 186 by are required for optimal basal and blue light-induced expression of this gene. The experiments lay the foundation for a simple genetic screen for light response mutants. 相似文献
6.
Stearidonic acid (18:4ω3), which is reported to be of rare occurrence in the plant kingdom and which is of considerable dietary and pharmaceutical interest has been found in three closely related Primula species. It occurs, together with γ-linolenic acid (3–4% of the seed oil total fatty acids), in significant percentages in Primula florindae (11%), P. sikkimensis (14%) and P. alpicola (14%). 18:4(ω3 may also be of chemotaxonomic interest in the genus Primula, as high levels may be typical for section Sikkimensis. The only commercial plant source of stearidonic acid known so far is the seed oil of Ribes nigrum. 相似文献
7.
Growth Yields and Maintenance Coefficients of Unadapted and NaCl-Adapted Tobacco Cells Grown in Semicontinuous Culture 总被引:1,自引:1,他引:0
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Comparison of carbon utilization between unadapted and NaCl (428 millimolar) adapted tobacco (Nicotiana tabacum L.) cells under substrate limited growth conditions was facilitated using semicontinuous culture. Growth yields (Yg) and maintenance coefficients (m) of unadapted and NaCl adapted cells were similar, indicating that the efficiency of carbon utilization for growth was not altered as a result of salt adaptation and that no additional metabolic costs were associated with growth of adapted cells in the presence of a high concentration (428 millimolar) of NaCl. The Yg (0.588 grams organic dry weight gain per gram sugar uptake) and m values (0.117 grams sugar uptake per gram organic dry weight per day) were comparable in spite of substantial physiological and biochemical differences that exist between unadapted and NaCl adapted cells. Apparently, a metabolic homeostasis governs biomass production of cells before and after adaptation to salinity. 相似文献
8.
9.
Dr. Gisela v. Raussendorff-Bargen 《Planta》1962,58(5):471-482
Zusammenfassung Zur Identifizierung der Streckungswuchsstoffe in Apfelgeweben wurden Extrakte aus vegetativen und reproduktiven Organen in verschiedenen Entwicklungsstadien chromatographiert und mit Hilfe des Weizen-Koleoptilzylinder-Tests, verschiedener Farbreagentien und synthetischer Vergleichssubstanzen auf ihre Wuchsstoffwirkung und ihren Gehalt an Indolderivaten geprüft. Alle untersuchten Gewebe ergaben im biologischen Test dieselben Wuchsstoffe, allerdings mit erheblichen quantitativen Unterschieden.In der sauren Fraktion von Ätherextrakten aus dem Fruchtfleisch verschiedener Apfelsorten ließen sich Malonyltryptophan, Indol-3-carbonsäure, 2-Hydroxy-indol-3-essigsäure, Indol-3-essigsäure, Indol-3-aldehyd (vor allem in reifen Früchten) und Indol-3-essigsäure-äthylester (in unreifen Früchten) identifizieren. In Gegenwart von IES trat häufig auch Indol-3-acetamid auf; dieses, die Indol-3-essigsäure und 2-Hydroxy-indol-3-essigsäure und der Indol-3-essigsäure-äthylester zeigten im Weizen-Koleoptilzylinder-Test Wuchsstoffwirkung.Nach Hydrolyse des mit Äther extrahierten Materials fanden sich neben einer größeren Anzahl unbekannter Substanzen, die im Farb-Test Indolreaktionen ergaben, drei weitere, im biologischen Test aktive Indolderivate, von denen das eine als Indol-3-acetylasparaginsäure identifiziert werden konnte; die anderen beiden sind möglicherweise ebenfalls Verbindungen der IES mit Aminosäuren.Im Weizen-Koleoptilzylinder-Test konnte eine Überlagerung der Indolderivate mit unbekannten, ebenfalls aktiven Substanzen nicht ausgeschlossen werden.Mit 3 Textabbildungen 相似文献
10.
Jonathan A. Coles Gisela Schneider-Picard 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1989,165(1):109-118
Summary Photoreceptor cells of the drone,Apismellifera , have a voltage-gated Na+ membrane conductance that can be blocked by tetrodotoxin (TTX) and generates an action potential on abrupt depolarization: an action potential is triggered by the rising phase of a receptor potential evoked by an intense light flash (Autrum and von Zwehl 1964; Baumann 1968). We measured the intracellular voltage response to a small (9%), brief (30 ms) decrease in light intensity from a background, and found that its amplitude was decreased by 1M TTX. The response amplitude was maximal when the background intensity depolarized the cell to –38 mV. With intensities depolarizing the cell membrane to –45 to –33 mV the average response amplitude was decreased by TTX from 1.2mV to 0.5mV. TTX is also known to decrease the voltage noise during steady illumination (Ferraro et al. 1983) but, despite this, the ratio of peak-to-peak signal to noise was, on average, decreased by TTX. The results suggest that drone photoreceptors use voltage-gated Na+ channels for graded amplification of responses to small, rapid changes in light intensity.Abbreviations
TTX
tetrodotoxin
-
V
i
intracellular potential with respect to the bath
-
V
o
extracellular potential
-
V
m,V
i-V
o
approximate transmembrane potential
-
S
amplitude of the voltage response to an 8.9% decrease in light intensity
-
N
voltage noise, usually measured as root mean square voltage deviation as described in Methods 相似文献