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11.
Bovine chromaffin granules undergo irreversible structural changes during osmotic shrinkage in hypertonic sucrose and salt solutions, such that, on reexposure to isoosmotic conditions they do not regain their original morphology, but undergo lysis ('hyperosmotic relaxation lysis'). Irreversible alterations of granules were induced by hypertonic incubations lasting for as little as 1 min. Fluorescence and EPR membrane labelling experiments showed that hypertonicity did not induce membrane loss for instance by inwardly or outwardly directed pinching off of membrane material. The mean sizes of chromaffin granules as a function of increasing and subsequently decreasing osmotic pressure were measured by photon correlation spectroscopy; there was no significant difference in sizes of hyperosmotically pretreated granules as compared with controls. Freeze-fracture electron micrographs showed the formation of 'twins' and 'triplets' under hypertonic conditions. They also revealed intragranular vesicles of 50-200 nm in diameter in both hypertonically and isotonically suspended granules. 'Twin' and 'triplet' granules were formed by the attachment of intragranular vesicles to the granule membranes. We suggest that hyperosmotic relaxation lysis is caused by the fact that this adhesion partly prevents the granule membrane from reexpanding, thus, leading to its rupture. 相似文献
12.
Abstract Detection of plant viruses by ELISA using different reagent strips
A simplified immunoassay for detection of plant viruses under field conditions was developed on the basis of the direct double antibody sandwich ELISA using dry reagent carriers immobilized on PVC-supports which are arranged in a fan-like manner. The fan consists of a first reagent carrier with antivirus IgG covalently bound to cyanuric chloride-activated (CCA) paper while the second and third are filter papers impregnated with alkaline phosphatase labelled antivirus IgG and the fluorogenic subsrate, 4-methylumbelliferylphosphate, respectively. Performing the test, the first carrier is contacted with a liquid sample containing the virus to be identified, the second and third carriers is contacted with a liquid sample containing the virus to be identified the second and third carriers are sequentially put one upon the other and the reactions carried out. The virus is detected by the reacted substrate fluorescing under a UV-light. The applicability of the test is demonstrated with cucumber mosaic virus and potato virus X. 相似文献
A simplified immunoassay for detection of plant viruses under field conditions was developed on the basis of the direct double antibody sandwich ELISA using dry reagent carriers immobilized on PVC-supports which are arranged in a fan-like manner. The fan consists of a first reagent carrier with antivirus IgG covalently bound to cyanuric chloride-activated (CCA) paper while the second and third are filter papers impregnated with alkaline phosphatase labelled antivirus IgG and the fluorogenic subsrate, 4-methylumbelliferylphosphate, respectively. Performing the test, the first carrier is contacted with a liquid sample containing the virus to be identified, the second and third carriers is contacted with a liquid sample containing the virus to be identified the second and third carriers are sequentially put one upon the other and the reactions carried out. The virus is detected by the reacted substrate fluorescing under a UV-light. The applicability of the test is demonstrated with cucumber mosaic virus and potato virus X. 相似文献
13.
Ca2+ release from mitochondria induced by prooxidants 总被引:3,自引:0,他引:3
A variety of chemically different prooxidants causes Ca2+ release from mitochondria. The prooxidant-induced Ca2+ release occurs from intact mitochondria via a route which is physiologically relevant and may be regulated by protein ADP-ribosylation. When the released Ca2+ is excessively cycled by mitochondria they are damaged. This leads to uncoupling, a decreased ATP supply, and a decreased ability of mitochondria to retain Ca2+. Excessive Ca2+ cycling by mitochondria will deprive cells of ATP. As a result, Ca2+ ATPases of the endoplasmic (sarcoplasmic) reticulum and the plasma membrane are stopped. The rising cytosolic Ca2+ level cannot be counterbalanced due to damage of mitochondria which, under normoxic conditions, act as safety device against increased cytosolic Ca2+. It is proposed that prooxidants are toxic because they impair the ability of mitochondria to retain Ca2+. 相似文献
14.
We report the identification, via their cDNAs, of genes which are temporarily transcribed during the initiation of somatic embryogenesis in carrot (Daucus carota L.) cells cultured in an auxin-free medium. Their expression is roughly associated with the first morphogenetic, or globular, stage. A cDNA library ( gt 10) was established using poly(A)+ -rich RNAs from cells deprived of auxin for 8 d. By differential screening a number of clones corresponding to early-induced embryogenic genes were identified. For several a temporary accumulation of the specific mRNA between 6 and 16 d after induction was observed. With regard to the nucleotide sequence and the respective deduced amino-acid sequence, two glycine-rich proteins and a polypeptide with a proline-rich domain were among the products of genes activated at the onset of somatic embryogenesis.Abbreviations b, bp
bases, basepairs
- 2,4-D
2,4-dichlorophenoxyacetic acid
Sequence data reported here will appear in the EMBL Genbank and DDBJ Nucleotide Sequence Databases under the following accession numbers: X 15436 for clone DC 2.15 (proline-rich protein), X 15706 for clone DC 7.1 (glycine-rich protein, DCGRP) and X 14067 for clone DC 9.1 (glycine-rich protein, DCGRP)This research was supported by the Deutsche Forschungsgemeinschaft. We thank Mrs. I. Liebscher for her competent assistance. 相似文献
15.
E. D. Jarvis R. L. Widom G. LaFauci Y. Setoguchi I. R. Richter R. Rudner 《Genetics》1988,120(3):625-635
Integrative mapping with vectors containing ribosomal DNA sequences were used to complete the mapping of the 10 rRNA gene sets in the endospore forming bacterium Bacillus subtilis. Southern hybridizations allowed the assignment of nine operons to distinct BclI restriction fragments and their genetic locus identified by transductional crosses. Nine of the ten rRNA gene sets are located between 0 and 70 degrees on the genomic map. In the region surrounding cysA14, two sets of closely spaced tandem clusters are present. The first (rrnJ and rrnW) is located between purA16 and cysA14 closely linked to the latter; the second (rrnI, rrnH and rrnG) previously mapped within this area is located between attSPO2 and glpT6. The operons at or near the origin of replication (rrnO,rrnA and rrnJ,rrnW) represent "hot spots" of plasmid insertion. 相似文献
16.
Biomanipulation and its feasibility for water quality management in shallow eutrophic water bodies in The Netherlands 总被引:5,自引:0,他引:5
A. F. Richter 《Aquatic Ecology》1986,20(1-2):165-172
Biomanipulation as a tool for lake restoration is discussed mainly using literature data. It is based on the exploitation of the interactions both within and between the trophic levels in an aquatic ecosystem. Important among the interactions are: competition for light and nutrients between aquatic macrophytes and phytoplankton and among different phytoplankton species; grazing by planktonic and benthic filter feeders; and size-selective predation by fish. In several case studies biomanipulation has proved to be successful in restorating mildly eutrophic small waterbodies. However, for long-term stability of the restored ecosystems supplementary measures like reducing the external nutrient loadings are needed. The feasibility of the different biomanipulation measures to improve the water quality in shallow Dutch lakes is discussed. Preliminary results on biomanipulation experiments in enclosures withOscillatoria agardhii and the benthic filter feederDreissena polymorpha are given. 相似文献
17.
The effect of seleno-DL-methionine, which has antioxidative properties, on the recovery of human platelets after freezing with 0.5 mol/liter glycerol or 0.7 mol/liter (5% v/v) dimethyl sulfoxide was investigated. Incubation of platelets with 2 mumol/liter seleno-DL-methionine for 30 min at room temperature before equilibration with the protective additives improved the post-thaw uptake of 5-hydroxytryptamine and the percentage reversal in the hypotonic stress test. The effect was small, but in view of the ability of seleno-DL-methionine to inhibit lipid peroxidation in membranes, the results suggest that oxidative damage is implicated in freezing injury. The dimethyl sulfoxide protocol apparently afforded greater protection to the platelets than the glycerol protocol. But, if the platelets were incubated for 24 hr at 37 degrees C after thawing, there was a marked improvement in the response of cells in the hypotonic stress test, particularly in the samples frozen with glycerol, and there was no longer any difference between the two additives. There was, however, a concomitant loss of almost half the number of cells in the thawed suspensions during the prolonged incubation at 37 degrees C. 相似文献
18.
The separation of 38 hypophyseal or hypothalamic peptides and proteins by reversed-phase HPLC is described. The efficacy of several supports is discussed: large-pore reversed-phase silica supports turned out to be most effective in the separation of neuropeptides and proteins. The use of high sodium phosphate and phosphoric acid in the eluent resulted in high yields and better separation. On the basis of this procedure, beta-lipotropin, beta-endorphin, and adrenocorticotropic hormone were prepared from porcine pituitary glands, and human neurophysins from human pituitary posterior lobes. Moreover, this system is used for the analysis of the perifusate of pituitary posterior lobes, showing the release of micro-heterogeneous neurophysins. 相似文献
19.
Development of flower buds in thin-layer cultures of floral stalk tissue from tobacco: Role of hormones in different stages 总被引:4,自引:0,他引:4
The in vitro development of flower buds was studied on tissue explants of epidermis and subepidermal cortex from the flower stalks of Nicotiana tabacum L. cv. Samsun. The number of flower buds formed depended mainly on cytokinin concentration. Auxin acted as a modifier in a complex way. In early development, NAA at 1 μ M decreased the number of buds initiated and delayed bud emergence. At a later stage, auxin promoted bud outgrowth at the same concentration. Optimal results were obtained when explants were first incubated at low auxin concentration for 3–5 days and subsequently transferred to an elevated auxin level. Physiological processes that lead to flower bud initiation start very soon after the onset of incubation. This was inferred from experiments whereby explants were first cultured at an inductive cytokinin concentration and then transferred to a non-inductive hormone level. 相似文献
20.
A theory of early visual information processing proposed by Marr and co-workers suggests that simple cortical cells may be involved in the detection of zero crossing in the retinal output. We have tested this theory by using pairs of adjacent edges (staircases stimuli) and recording from edge-specific simple cells in cat striate cortex. The zero crossing hypothesis gives rise for such stimuli to non-obvious predictions that were generally confirmed by the experiment. 相似文献