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21.
Harald Sverdrup Salim Belyazid Bengt Nihlg?rd Lars Ericson 《Plant Growth Regulation》1991,10(2):173-174
Book Review
Plant protoplasts and genetic engineering IIY.P.S. Bajaj (Ed.), (Biotechnology in Agriculture and Forestry, Vol. 9). Berlin: Springer-Verlag, 1989. 510 pages. DM398.00. ISBN 3-540-50789-2 相似文献22.
23.
Else K. Hoffmann Ian H. Lambert Lars Ole Simonsen 《The Journal of membrane biology》1986,91(3):227-244
Summary The net loss of KCl observed in Ehrlich ascites cells during regulatory volume decrease (RVD) following hypotonic exposure involves activation of separate conductive K+ and Cl– transport pathways. RVD is accelerated when a parallel K+ transport pathway is provided by addition of gramicidin, indicating that the K+ conductance is rate limiting. Addition of ionophore A23187 plus Ca2+ also activates separate K+ and Cl– transport pathways, resulting in a hyperpolarization of the cell membrane. A calculation shows that the K+ and Cl– conductance is increased 14-and 10-fold, respectively. Gramicidin fails to accelerate the A23187-induced cell shrinkage, indicating that the Cl– conductance is rate limiting. An A23187-induced activation of42K and36Cl tracer fluxes is directly demonstrated. RVD and the A23187-induced cell shrinkage both are: (i) inhibited by quinine which blocks the Ca2+-activated K+ channel. (ii) unaffected by substitution of NO
3
–
or SCN– for Cl–, and (iii) inhibited by the anti-calmodulin drug pimozide. When the K+ channel is blocked by quinine but bypassed by addition of gramicidin, the rate of cell shrinkage can be used to monitor the Cl– conductance. The Cl– conductance is increased about 60-fold during RVD. The volume-induced activation of the Cl– transport pathway is transient, with inactivation within about 10 min. The activation induced by ionophore A23187 in Ca2+-free media (probably by release of Ca2+ from internal stores) is also transient, whereas the activation is persistent in Ca2+-containing media. In the latter case, addition of excess EGTA is followed by inactivation of the Cl– transport pathway. These findings suggest that a transient increase in free cytosolic Ca2+ may account for the transient activation of the Cl– transport pathway. The activated anion transport pathway is unselective, carrying both Cl–, Br–, NO
3
–
, and SCN–. The anti-calmodulin drug pimozide blocks the volume- or A23187-induced Cl– transport pathway and also blocks the activation of the K+ transport pathway. This is demonstrated directly by42K flux experiments and indirectly in media where the dominating anion (SCN–) has a high ground permeability. A comparison of the A23187-induced K+ conductance estimated from42K flux measurements at high external K+, and from net K– flux measurements suggests single-file behavior of the Ca2+-activated K+ channel. The number of Ca2+-activated K+ channels is estimated at about 100 per cell. 相似文献
24.
Lars Werdelin John A. Long 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1986,19(2):161-169
A set of 18 measurements of the dermal armour of Bothriolepis canadensis Whiteaves (Placodermi, Anti-archa) is analysed with respect to allometric growth patterns. The strongest allometric patterns were found for the orbital fenestra and premedian plate of the head-shield. and the anterior median dorsal plate of the trunk-shield. These are all areas of the greatest importance in antiarch phylogeny and imply a role for ontogenetic effects such as paedomorphosis in the evolution of antiarchs. It is suggested that this is partly a result of the severe constraints on growth in a closed box such as the armour of placoderms, and may be generally true of such arrangements. 相似文献
25.
Brain Cell Biology - Cytochemical techniques were used to study the localization of 5′-nucleotidase in the enteric ganglia and in smooth muscle cells of the guinea-pig ileum, iris and vas... 相似文献
26.
Lars Olof Björn 《Physiologia plantarum》1984,60(3):369-372
Experiments by several authors on the effects of polarized light on phytochromemediated responses in fern gametophytes and in the green alga Mougeotia have earlier been interpreted as showing that the transition moment of phytochrome in the Pr form is parallel to the plasmalemma, but perpendicular to the plasmalemma for the Pfr form of phytochrome. It is now shown that the experimental results can be interpreted differently, and that they are also consistent with a chromophore rotation of about 30° (instead of 90°), as found for immobilized phytochrome molecules in vitro. Thus there is no evidence for a rotation of the whole phytochrome protein. For the gametophyte of Adiantum it is calculated that the Pr transition moment is inclined 17° to the plasmalemma, and the Pfr transition moment ca 50°, corresponding to an in vivo chromophore rotation of ca 33°; however, these values are very approximate. 相似文献
27.
Steen Kølvraa Torben A. Kruse P. K. A. Jensen Kirsten H. Linde Søren R. Vestergaard Lars Bolund 《Human genetics》1986,74(3):284-287
Summary EDA (ectodermal dysplasia, anhidrotic) is an X-linked recessive disorder characterized by hypohidrosis, hypoor anodontia, and hypotrichosis. A possible linkage between the gene for EDA and a number of restriction fragment length polymorphisms (RFLPs) spread over the X chromosome was investigated in two Danish families segregating EDA. No recombination between the gene for EDA and our probe pTAK8, which detects a two allele polymorphism in the region Xp11-q12, was found in nine informative meiotic events (seven of which are phase known), giving a maximal lod score of 2.41 at a recombination fraction of 0.00. This juxtacentromeric location of the gene for EDA agrees well with the linkage data obtained with the other markers used in this study. 相似文献
28.
Summary A new freeze-drier for histochemical use is described. It uses a refrigerated cooling bath for outer cooling and large amounts of phosphorous pentoxide as water vapor trap.The main features are a very high drying capacity, a simple, reliable easy-to-handle construction and a series of safety devices which, including a rigid stainless steel vacuum chamber which cannot implode, ensures reproducable results.Estimations of relative dryness can be performed during drying. An extra blind flange entrance to the vacuum chamber and the use of standard vacuum connections makes the apparatus versatile. Thus it can be used also for chemical freeze-drying.The apparatus was developed for use with the Falck-Hillarp fluorescence technique for histochemical visualization of monoamines. It gives excellent results with this technique both with peripheral tissues and brain tissue. As many as 20–25 whole brains from adult rats can be processed simultaneously within 3 days. 相似文献
29.
Rat liver microsomes catalyze the hydrolysis of the triphosphates of adenosine, guanosine, uridine, cytidine, and inosine into the corresponding diphosphates and inorganic orthophosphate. The activities are stimulated by Na2S2O4, and inhibited by atebrin, chlorpromazine, sodium azide, and deaminothyroxine. Sodium deoxycholate inhibits the ATPase activity in a progressive manner; the release of orthophosphate from GTP and UTP is stimulated by low, and inhibited by high, concentrations of deoxycholate, and that from CTP and ITP is unaffected by low, and inhibited by high, concentrations of deoxycholate. Subfractionation of microsomes with deoxycholate into ribosomal, membrane, and soluble fractions reveals a concentration of the triphosphatase activity in the membrane fraction. Rat liver microsomes also catalyze the hydrolysis of the diphosphates of the above nucleosides into the corresponding monophosphates and inorganic orthophosphate. Deoxycholate strongly enhances the GDPase, UDPase, and IDPase activities while causing no activation or even inhibition of the ADPase and CDPase activities. The diphosphatase is unaffected by Na2S2O4 and is inhibited by azide and deaminothyroxine but not by atebrin or chlorpromazine. Upon fractionation of the microsomes with deoxycholate, a large part of the GDPase, UDPase, and IDPase activities is recovered in the soluble fraction. Mechanical disruption of the microsomes with an Ultra Turrax Blender both activates and releases the GDPase, UDPase, and IDPase activities, and the former effect occurs more readily than the latter. The GDPase, UDPase, and IDPase activities of the rat liver cell reside almost exclusively in the microsomal fraction, as revealed by comparative assays of the mitochondrial, microsomal, and final supernatant fractions of the homogenate. The microsomes exhibit relatively low nucleoside monophosphatase and inorganic pyrophosphatase activities, and these are unaffected by deoxycholate or mechanical treatment. Different approaches toward the function of the liver microsomal nucleoside tri- and diphosphatases are reported, and the possible physiological role of the two enzymes is discussed. 相似文献
30.
This study presents 8 dogs of German Shepherd breed (6 males, 2 females, 2–5 years of age at onset of the disease) with a lupus like syndrome characterized by febrile polyarthritis, wasting, nephropathy, cutaneous lesions and high positive titres of ANA (antinuclear antibodies) of speckled type. The serum autoantibodies were further characterized by double immunodiffusion against ENA (extractable nuclear antigen), ELISA for Histone antibodies (Histon fraction H-24A and H-3S), indirect IF on rat-liver sections, non treated and RNase/DNase digested sections for DNP/RNP antibodies, and smears of a nemoflagellate C. luciliae for antibodies vs doubbel strained DNA, (dsDNA). Thus, the high ANA titres in these dogs represent varying types of autoantibodies against nucleoproteins of both DNA and RNA nature, associated histone antigens and non-histone antibodies (RNA and Sm) as well. Rheumatoid Factor titres in serum from these dogs were low or negative. Immunoglobulin deposits at dermo-epidermal junctions were demonstrated in some of the dogs with hyperkeratotic skin lesions. High concentration of serum-IgG was a constant finding in combination with anemia and in most cases leukopenia probably related to the chronic inflammatory process in these animals. Autoimmune hemolytic anemia (AIHA) or thrombocytopenia was not detected in these dogs. 相似文献