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21.
The influence of two enzyme solutions, differing only in the presence or absence of Macerozyme, on protoplast yield, colony formation and transient GUS (-glucuronidase) activity was studied. For all parameters tested the presence of Macerozyme during protoplast isolation had a negative influence. Using an enzyme solution without Macerozyme suspension aggregates gave up to 4.4 times higher protoplast yield and plating efficiencies were increased up to 10-fold. Further, protoplasts isolated without macerozyme showed a 5.2-fold higher GUS activity in transient gene expression. Apart from the presence of Macerozyme, longer incubation (3 compared with 1.5 h) of cell aggregates in the enzyme solution also had a negative effect on transient transformation efficiency. These data demonstrate that protoplast isolation conditions have a profound effect on transient gene expression and it is proposed that these factors will also influence stable transformation efficiency.Abbreviations CP
cellulase pectolyase
- CPM
cellulase pectolyase Macerozyme
- 2,4-d
2,4-dichlorophenoxyacetic acid 相似文献
22.
Arlette Pesty Brigitte Lefvre Jacek Kubiak Grard Graud Jan Tesarik Bernard Maro 《Molecular reproduction and development》1994,38(2):187-199
The incubation of mechanically denuded mouse oocytes in medium containing LiCl delayed both germinal vesicle breakdown (GVBD) and polar body extrusion in a dose-dependent and reversible manner. When myo-inositol alone was added to the culture medium, we observed that it accelerated GVBD and increased the rate of polar body extrusion, whereas, when combined with LiCl, the normal timing of GVBD was recovered. In the same way, when inositol trisphosphate (InsP3) was microinjected into the ooplasma, we observed an important improvement of the rate of GVBD, as compared to control oocytes, and prevention of lithium inhibition. However, neither myo-inositol nor InsP3 were able to rescue totally the oocytes from the negative effect of lithium on polar body extrusion. Moreover, lithium induced some important changes in microtubule and chromosome organizations. Before extrusion of the first polar body, the reduction of the spindle size or the appearance of short individualized chromosomes dispersed around a large aster of microtubules were often observed, whereas, after polar body extrusion, the spindle appeared smaller and chromosomes were often trapped in the midbody. Thus lithium affects mouse oocyte maturation at two different levels: GVBD and polar body extrusion. Whereas the former seems to be affected via polyphosphoinositide turnover, the latter is InsP3-independent and seems to be influenced negatively via underdevelopment of microtubular structures. © 1994 Wiley-Liss, Inc. 相似文献
23.
Differential expression of two related amino acid transporters with differing substrate specificity in Arabidopsis thaliana 总被引:8,自引:3,他引:5
Marion Kwart Brigitte Hirner Sabine Hummel Wolf B. Frommer 《The Plant journal : for cell and molecular biology》1993,4(6):993-1002
A general amino acid permease cDNA ( AAP2 ) was isolated from Arabidopsis by complementation of a yeast mutant defective in citrulline uptake. Direct transport measurements in yeast show that the protein mediates uptake of l -[14 C]-citrulline and l -[14 C]-proline. Detailed analyses of the substrate specificity by competition studies demonstrate that all proteogenic amino acids are recognized by the carrier, including those that represent the major transport forms of reduced nitrogen in many species, i.e. glutamine, glutamate and asparagine. Thus, AAP2 is less selective as compared with AAP1 and transports basic amino acids such as histidine as shown by expression in a histidine transport-deficient yeast strain. The predicted polypeptide of 53 kDa is highly hydrophobic with 12 putative membrane-spanning regions and shows significant homologies to the Arabidopsis broad specificity permease AAP1, and a limited homology to bacterial branched chain amino acid transporters, but not to any other known proteins. Alterations in the charged residues as compared with AAP1 in four regions might be involved in the difference in selectivity towards basic amino acids. Both genes are highly expressed in developing pods indicating a role in supplying the developing seeds with reduced nitrogen. AAP2 is selectively expressed in the stem and might therefore play a role in xylem-to-phloem transfer of amino acids during seed filling. Furthermore in situ hybridization shows that both genes are expressed in the vascular system of cotyledons in developing seedlings. 相似文献
24.
We examined the effects of the conversion of tropical forest to pasture on soil organic matter (SOM) origin and quality along
a chronosequence of sites, including a primary forest and six pastures. Bulk soil samples received a physical size-fractionation
treatment to assess the contribution of each compartment to total SOM pool. Besides a general increase in total C and N stocks
along the chronosequence, we observed a reduction of the relative contribution of the coarser fractions to total soil C content,
and an increased concentration in the finer fractions. The origin of the C in each size fraction was established from measurements
of13C abundance. After 80 years about 93% of the C in the least humified fraction of the top 10 cm of soil was of pasture origin,
while in the most humified it was 82%. Chemical analyses indicated that the fine silt and coarse clay fractions contained
the most refractory carbon. 相似文献
25.
Christiane Chine Michael Fountoulakis Heinz Dbeli Brigitte D'Arcy Fritz Winkler Allan D'Arcy 《Proteins》1995,23(4):591-594
A complex of human interferon-γ (IFN- γ) with the soluble extracellular domain of the IFN- γ receptor α-chain (IFN-γ-R) has been crystallised. Crystals of the complex were grown using PEG 4000 as the precipitating agent in the presence of β-octyl glucoside. The receptor-ligand complex crystallizes in a monoclinic space group and diffracts to about 3.0 Å resolution. Isomorphous crystals have been obtained with complex containing selenomethionine and cysteine mutants of IFN-γ, which may facilitate the ongoing X-ray structure determination. © 1995 Wiley-Liss, Inc. 相似文献
26.
Zusammenfassung Die vorliegende Untersuchung befaßt sich mit besonderen Haarfeinstrukturen der Soricidae, wobei geklärt werden soll, ob dem H-förmigen Haarquerschnitt-Profil eine taxonomische Bedeutung zukommt. Wir überprüften deshalb die betreffenden Haarstrukturen mit Hilfe des REM in 8 Gattungen.Das besondere Haarprofil, das auf das Terminalsegment der Grannenhaare beschränkt ist, findet sich bei folgenden Gattungen:Sorex, Neomys, Blarina undCryptotis, alles Vertreter der Subfamilie Soricinae. Sämtliche untersuchten Vertreter der Subfamilie Crocidurinae, d.h.Crocidura, Praesorex, Suncus undSylvisorex weisen ein einfaches Haarprofil auf.Das H-Profil wird als Synapomorphie der Soricinae angesehen und charakterisiert diese als monophyletische Gruppe. Die haarmorphologischen Kriterien ergänzen somit die osteologischen Kriterien von Repenning (1967) und sprechen für die Beibehaltung der von vielen Autoren abgelehnten Subfamilien.
Mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung (Nr. 3.515.71, 3.821.72, 3.413-0.74)
Unser Dank gilt Herrn Prof. N. Schönenberger, Herrn Prof.R. Krstic und Frau C. Regamey, die uns bei der histologischen Präparation behilflich waren, insbesondere auch Herrn Dr. T. Jalanti, der uns in die REM-Technik einführte. Kostbares Material wurde uns von Frau A. Geraets (Bonn), Herrn Prof. U. Rahm (Basel) und Herrn Dr. V. Aellen (Genf) zur Verfügung gestellt; auch ihnen sei hierfür herzlich gedankt. 相似文献
Special hair structures in Soricidae (Mammalia, Insectivora) and their taxonomic interpretation
Summary The following study should clear up the structures of the H-shaped profile found in the hairs of some shrews and show if it has a taxonomic signification. Therefore we studied the concerned hair structures by scanning electron microscopy in 8 genera.The special hair-shape, which is confined to the terminal segment of guard hairs, is found in the species of the following genera:Sorex, Neomys, Blarina andCryptotis, all members of the subfamily Soricinae. All the examined members of the subfamily Crocidurinae, i.e.Crocidura, Praesorex, Suncus andSylvisorex show a simple hair shape.The H-shaped hair characterizes the Soricinae as a monophyletic unity. Yet, the morphological criteria of hair complete the osteological criteria of Repenning (1967) an plead for the validitiy of the often refuted subfamilies.
Mit Unterstützung des Schweizerischen Nationalfonds zur Förderung der wissenschaftlichen Forschung (Nr. 3.515.71, 3.821.72, 3.413-0.74)
Unser Dank gilt Herrn Prof. N. Schönenberger, Herrn Prof.R. Krstic und Frau C. Regamey, die uns bei der histologischen Präparation behilflich waren, insbesondere auch Herrn Dr. T. Jalanti, der uns in die REM-Technik einführte. Kostbares Material wurde uns von Frau A. Geraets (Bonn), Herrn Prof. U. Rahm (Basel) und Herrn Dr. V. Aellen (Genf) zur Verfügung gestellt; auch ihnen sei hierfür herzlich gedankt. 相似文献
27.
UV-induced allevation of lambda restriction in Escherichia coli K-12: kinetics of induction and specificity of this SOS function 总被引:11,自引:0,他引:11
Summary In UV-irradiated cells of Escherichia coli K-12 a partial release of the restriction of non-modified phage is observed when the cells are recA
+
lexA
+. We show here that the induction of this restriction allevation (RA) also depends on the recBC enzyme and that the expression of RA requires protein synthesis. Maximum expression was reached within 60 to 90 min after irradiation. Experiments are presented which show that upon UV-irradiation a signal is created which triggers the development of RA when protein synthesis is allowed. This signal decayed with a half-life of only a few minutes in cells treated with chloramphenicol. The decay kinetics were similar in uvr
+ and uvrA mutants. RA appeared to be specific for EcoK insofar as no allevation of restriction by EcoRI, EcoRII and EcoP1 occurred. During maximum expression of RA no gross reduction of the activities of the recBC enzyme (exonuclease V) and the restriction endonuclease EcoK was observed and no new DNA modifying activity appeared in the cells. Since, in fully expressed cells, up to 75% of the infecting DNA was converted to acid-soluble material within 20 min after infection we suggest that only a small specific fraction of infections may undergo RA. 相似文献
28.
Dr. Brigitte Krisch 《Cell and tissue research》1980,205(3):453-471
Summary The present ultrastructural results indicate that, in the rat, the vasopressin-synthesizing perikarya of the supraoptic nucleus (NSO) attain a certain degree of maturity earlier than those of the paraventricular nucleus (NPV). In the neonate rat, the stainability of the nuclear areas is very weak; in the perikarya of the NSO a few labeled granules can be found, whereas the perikarya of the NPV often display only a labeled Golgi area, the cytoplasm being devoid of granules. At the end of the first (NSO) and the second (NPV) postnatal weeks, the filling of the neurosecretory granules with vasopressin is inhomogeneous with irregular spots of reaction product distributed on the granules. This feature is less obvious during the following week and has nearly disappeared after the third and fourth postnatal weeks. Already in the neonate two types of vasopressin-positive fibers are observed in the median eminence, characterized by the different diameters of their granules and by their typical location in the internal and the external pericapillary contact zone. Especially in one and two week-old animals, in the internal zone of the median eminence and, to a lesser degree in the neural lobe, the immunocytochemical reaction product is deposited on an axonal tubular network. Judging from the presence of very few vasopressin-negative fibers in the neural lobe of the neonate, the development of the oxytocin system appears to be delayed. A characteristic relationship between pituicytes and the neurosecretory fibers can be observed during the first two postnatal weeks. After the third postnatal week the immunocytochemical features of the vasopressin system correspond approximately to that in adult rats.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/3) and Stiftung Volkswagenwerk 相似文献
29.
The measurement of the intrinsic alkaline Bohr effect of various human haemoglobins by isoelectric focusing 下载免费PDF全文
We have used isoelectric focusing to measure the differences between the pI values of various normal and mutant human haemoglobins when completely deoxygenated and when fully liganded with CO. It was assumed that the ΔpI(deox.–ox.) values might correspond quantitatively to the intrinsic alkaline Bohr effect, as most of the anionic cofactors of the haemoglobin molecule are `stripped' off during the electrophoretic process. In haemoglobins known to exhibit a normal Bohr coefficient (ΔlogP50/ΔpH) in solutions, the ΔpI(deox.–ox.) values are lower the higher their respective pI(ox.) values. This indicates that for any particular haemoglobin the ΔpI(deox.–ox.) value accounts for the difference in surface charges at the pH of its pI value. This was confirmed by measuring, by the direct-titration technique, the difference in pH of deoxy and fully liganded haemoglobin A0 (α2β2) solutions in conditions approximating those of the isoelectric focusing, i.e. at 5°C and very low concentration of KCl. The variation of the ΔpH(deox.–ox.) curve as a function of pH (ox.) was similar to the isoelectric-focusing curve relating the variation of ΔpI(deox.–ox.) versus pI(ox.) in various haemoglobins with Bohr factor identical with that of haemoglobin A0. In haemoglobin A0 the ΔpI(deox.–ox.) value is 0.17 pH unit, which corresponds to a difference of 1.20 positive charges between the oxy and deoxy states of the tetrameric haemoglobin. This value compares favourably with the values of the intrinsic Bohr effect estimated in back-titration experiments. The ΔpI(deox.–ox.) values of mutant or chemically modified haemoglobins carrying an abnormality at the N- or C-terminus of the α-chains are decreased by 30% compared with the ΔpI value measured in haemoglobin A0. When the C-terminus of the β-chains is altered, as in Hb Nancy (α2βTyr-145→Asp2), we observed a 70% decrease in the ΔpI value compared with that measured in haemoglobin A0. These values are in close agreement with the estimated respective roles of the two major Bohr groups, Val-1α and His-146β, at the origin of the intrinsic alkaline Bohr effect [Kilmartin, Fogg, Luzzana & Rossi-Bernardi (1973) J. Biol. Chem. 248, 7039–7043; Perutz, Kilmartin, Nishikura, Fogg, Butler & Rollema (1980) J. Mol. Biol. 138, 649–670]. In other mutant haemoglobins it is demonstrated also that the ΔpI(deox.–ox.) value may be decreased or even suppressed when the substitution affects residues involved in the stability of the tetramer. These results support the interpretation proposed by Perutz, Kilmartin, Nishikura, Fogg, Butler & Rollema [(1980), J. Mol. Biol. 138, 649–670] for the mechanism of the alkaline Bohr effect, and also indicate that the transition between the two quaternary configurations is a prerequisite for the full expression of the alkaline Bohr effect. 相似文献
30.
Summary Examination of serial semithin sections of rat kidney cortex and a subsequent electron microscopic study of selected areas revealed that the characteristic epithelium of the cortical part of the thick ascending limb of Henle extends for a varying distance beyond the macula densa. The transition from the relatively thin epithelium of the thick ascending limb at this site to the three -or even four-fold thicker epithelium of the convoluted part of the distal tubule is sharply defined and occurs without the interposition of an intermediate cell type.The position of the macula densa at the end but still clearly within the ascending limb of Henle's loop is functionally interpreted to guarantee the separation of the sensor point macula densa from disturbing influences which might arise from the secretory activity of the subsequent tubular portion.Investigations supported by the Deutsche Forschungsgemeinschaft. The skillful technical assistance of Mrs. Saliha Sabanovic is gratefully acknowledged 相似文献