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51.
Volume regulation by flounder red blood cells in anisotonic media   总被引:4,自引:2,他引:2       下载免费PDF全文
The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.  相似文献   
52.
We have developed an automated procedure for determining bone-age in the monkey, Macaca fascicularis. The status of epiphysial junctions and sesamoids were determined from radiographs. Epiphyses were scored as either open or closed, and sesamoids were scored as either present or absent. Bone-age was calculated by a computer program that stored and used a data base of probabilities for epiphysial closure and sesamoid appearance. The simplicity of scoring, combined with the speed and accuracy of the calculations, make this technique potentially adaptable for use in a variety of primate species.  相似文献   
53.
54.
Summary The results are given of experiments to test wether leaf analyses can be used for diagnostic determinations of deficiency and excess in mineral nutrition of lettuce in soilless culture. re]19760127  相似文献   
55.
M R Sutton  D Rosen  G Feher  L A Steiner 《Biochemistry》1982,21(16):3842-3849
We have determined the sequence of the 25-28 amino-terminal residues of the three subunits, L, M, and H, of the membrane-bound reaction center protein of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. The sequences are as follows: L, H2N-Ala-Leu-Leu-Ser-Phe-Glu-Arg-Lys-Tyr-Arg- Val-Pro-Gly-Gly-Thr-Leu-Val-Gly-Gly-Asn-Leu-Phe-Asp-Phe-(His)-Val-; M, H2N-Ala-Glu-Tyr-Gln-Asn-Ile-Phe-Ser-Gln-Val-Gln-Val-Arg-Gly-Pro-Ala-Asp-Leu-Gly-Met-Thr-Glu-Asp-Val-Asn-Leu-Ala-Asn-; H, H2N-Met-Val-Gly-Val-Thr-Ala-Phe-Gly-Asn-Phe-Asp-Leu-Ala-Ser-Leu-Ala-Ile-Tyr-Ser-Phe-Trp-Ile-Phe-Leu-Ala-X-Leu-Ile-. The H sequence, especially after the aspartyl residue at position 11, is rich in hydrophobic residues, consistent with the possibility that this section of the polypeptide chain is located within the membrane. The L sequence is hydrophilic near the amino terminus and then becomes moderately hydrophobic. The M sequence is of average polarity.  相似文献   
56.
In the present study 36 police officers were exposed to a psychological stressor (IQ quiz) and to cold pressor stress while several cardiovascular variables were monitored. Impedance cardiography was used to provide measures of heart rate, stroke volume, cardiac output, myocardial contractility, and total peripheral resistance. In addition, measures of systolic and diastolic blood pressure and peripheral skin temperature were obtained. A multivariate analysis of variance (MANOVA) indicated that significant increases in diastolic and systolic blood pressure during the cold pressor test were mediated by large increases in total peripheral resistance, whereas blood pressure elevation during the IQ quiz were accompanied by significant increases in heart rate and, to a lesser extent, cardiac output. Peripheral skin temperature decreased in response to each stressor. Additional analysis indicated a degree of stimulus specificity for several variables. For example, diastolic blood pressure showed greater increases to cold pressor than quiz, whereas systolic blood pressure increased more with the psychological than the physical stressor. Directional fractionation occurred for both myocardial contractility and cardiac output.  相似文献   
57.
Zusammenfassung Im Herbst 1984 schliefen mindestens 50 Hohltauben (Columba oenas), wahrscheinlich aber wesentlich mehr, an drei verschiedenen Stellen auf grobscholligen Sturzäckern der offenen Ackerlandschaft des Marchfeldes östlich von Wien. Bäume verwendeten sie nur als Sammelplatz. Im gleichen Zeitraum war auch ein traditioneller Schlafplatz zusammen mit Türkentauben (Streptopelia decaoto) in einem Wiener Randbezirk (16 km entfernt) benutzt; er lag in einem Gehölz.
Stock Doves (Columba oenas) roosting also in open fields
Summary In autumn 1984, at least 50 — probably many more — Stock Doves roosted in open fields, roughly ploughed, east of Vienna. The nearest trees, 200 metres distant, were used only as perches until darkness approached. Some 16 km distant, another roosting place in trees was shared with Collared Doves (Streptopelia decaocto).
  相似文献   
58.
Subpopulations of different proliferative status are determined during cell-density dependent proliferation of 3T3 cells. From these data the probability of conversion of proliferative to quiescent cells is derived and found to correlate well with published data on binding of growth-inhibiting factors secreted from growth-inhibited cells.Based on material presented at the Symposium Intercellular Communication Stuttgart, September 16–17, 1982  相似文献   
59.
We developed a specific antibody to the catalytic subunit (C-subunit) of cyclic AMP-dependent protein kinase and used it to localize C- subunit in cultured cells. C-subunit antigen was purified from bovine cardiac muscle and cross-linked to hemocyanin with glutaraldehyde. Immunized goat serum showed a low titer of antibody after boosting; it was enriched 100-fold by affinity chromatography on catalytic subunit- Sepharose. The antibody immunoprecipitated C-subunit from type I and type II holoenzyme and depleted enzymatic activity from solution. At 12.5 nM antigen, 1 microgram antibody immunoprecipitated 10 ng of C- subunit. Immunoprecipitation of 35S-labeled cell extracts and 125I- antibody detection on nitrocellulose paper revealed that the antibody specifically reacts with C-subunit in Chinese hamster ovary (CHO) whole cell extracts. Using indirect immunofluorescence to localize C-subunit, we found a pattern of diffuse staining in the cytoplasm of CHO cells with little or no nuclear staining. A similar distribution of the enzyme was observed in Swiss 3T3 cells, bovine endothelial tracheal cells, human lung fibroblasts and NRK cells. Treatment of CHO cells with 8-bromo-cyclic AMP produced no change in the pattern or intensity of immunofluorescence. We conclude that the majority of C-subunit is localized in cytoplasm and that in cultured fibroblasts exposure to cyclic AMP analogues causes no apparent redistribution of catalytic subunit.  相似文献   
60.
A method for unambiguously determining the initiator methionine residue and the adjacent NH2-terminal amino acid sequence of cell-free translation products of eukaryotic messenger RNA is described. In this procedure, the NH2 termini of nascent peptides are blocked by incorporating labeled formylmethionine instead of methionine, using yeast initiator tRNA in the wheat germ cell-free system. After immunoprecipitation of the desired product the radiolabeled material is treated with dansyl-Cl to irreversibly block all remaining free amino groups. The material is then deformylated by mild acid hydrolysis and subjected to automated Edman degradation. Only those products that had been synthesized with formylmethionine residues at their NH2-termini can then give rise to labeled phenylthiohydantoin derivatives during degradation. Using this method, we have defined the initiation sites in both rat preproinsulin and pregrowth hormone messenger RNAs.  相似文献   
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