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61.
62.
Andreas Pries Alexander Steinbüchel Hans G. Schlegel 《Applied microbiology and biotechnology》1990,33(4):410-417
Summary Transposon Tn 951-encoded -galactosidase was expressed in Pseudomonas saccharophila and enabled this bacterium to grow on lactose as sole carbon source. In contrast, -galactosidase was not expressed in Alcaligenes eutrophus even if the lacZ gene of Tn 951 was separated from the lacI gene. However, -galactosidase was expressed in A. eutrophus, if a DNA fragment, which was suspected to harbour the promoter of the A. eutrophus poly(3-hydroxybutyric acid)-synthetic genes, was ligated to the promoter probe vector pMC1403, which employs lac Z, Y as reporter genes. Plasmid pPL76, which harboured one of the promoter-lac fusions, enabled A. eutrophus not only to express -galactosidase but also to grow slowly on lactose (doubling time = 25–30 h). Subsequently, the promoter-lac fusion was ligated to Tn5 in pSUP5011 and was inserted into the genome of A. eutrophus H16 and of the glucose-utilizing mutant H16-G+1 by applying the suicide plasmid technique. Two recombinant strains, H16-cPL and H16-G+1-cPL, which grow with a doubling time of 16–23 h on lactose, were investigated in detail. The cells only utilized the glucose residue of lactose as a carbon source for grouth and excreted galactose into the medium. Only after the Escherichia coli gal operon had been cloned in vector pVK101 and had been mobilized to H16-cPL or H16-G+1-cPL, was lactose completely utilized; no galactose was detected in the medium and the growth yields increased twofold. Depending on the orientation of the gal operon in pVK101, the expression of galactokinase seems to be dependent either on the promoter of aminoglycoside phosphotransferase gene (kan) or on the promoter of the tetR gene.
Offprint requests to: A. Steinbüchel 相似文献
63.
Kirstin Schultze Klaus Janke Andreas Krüß Wolfgang Weidemann 《Helgoland Marine Research》1990,44(1):39-51
This paper describes the macroflora and macrofauna associated with two bull kelp species,Laminaria hyperborea andL. digitata, at the island of Helgoland, North Sea. During a study period of seven months (March–September 1987), 29 macroflora species
and 125 macrofauna species were found. The dominant taxonomic groups were Polychaeta (25 species), Bryozoa (17), Amphipoda
(14), Hydrozoa (10) and Ascidiae (8). The species maximum was in July. In general,L. hyperborea was preferred as a substrate for settlement toL. digitata. Composition of the communities associated with kelp changed during the season according to exposure to wave action, and
according to location on the kelp thallus. The rhizoid community of both kelps bore more species at exposed locations. Wave-exposedL. digitata lacked obvious faunal settlement on both phylloid and cauloid. Phylloid and cauloid ofL. hyperborea were chosen as an attractive substrate at both sheltered and wave-exposed locations, showing an association of encrusting
bryozoan and hydrozoan colonies. 相似文献
64.
Eva-Marià Kupsch Dominique Aubel Carol P. Gibbs Andreas F. Kahrs Thomas Rudel Thomas F. Meyer 《Molecular & general genetics : MGG》1996,250(5):558-569
A versatile shuttle system has been developed for genetic complementation with cloned genes of transformable and non-transformableNeisseria mutants. By random insertion of a selectable marker into the conjugativeNeisseria plasmidptetM25.2, a site within this plasmid was identified that is compatible with plasmid replication and with conjugative transfer of plasmid. Regions flanking the permissive insertion site of ptetM25.2 were cloned inEscherichia coli and served as a basis for the construction of the Hermes vectors. Hermes vectors are composed of anE. coli replicon that does not support autonomous replication inNeisseria, e.g. ColE1, p15A, orori
fd, fused with a shuttle consisting of a selectable marker and a multiple cloning site flanked by the integration region of ptetM25.2. Complementation of a non-transformableNeisseria strain involves a three-step process: (i) insertion of the desired gene into a Hermes vector; (ii) transformation of Hermes into aNeisseria strain containing ptetM25.2 to create a hybrid ptetM25.2 via gene replacement by the Hermes shuttle cassette; and (iii) conjugative transfer of the hybrid ptetM25.2 into the finalNeisseria recipient. Several applications for the genetic manipulation of pathogenicNeisseriae are described. 相似文献
65.
Andreas Schmidt-Rhaesa 《Zoomorphology》1996,116(3):133-142
The nervous system of Nectonema munida is shown to be composed of a brain, a ventral nerve cord with an anterior and a posterior enlargement, a dorsal nerve cord
and a plexus-like basiepidermal nervous system. The ultrastructure of these parts is given. Additionally, the ventral nerve
cord of Gordius aquaticus is ultrastructurally described. The results are compared with the literature to work out the ground pattern of the Nematomorpha
according to the nervous system. This contains a circumpharyngeal brain with a main subpharyngeal portion and a weak suprapharyngeal
portion, a ventral and dorsal intraepidermal nerve cord and a peripheral nervous system. The ground pattern of the nervous
system of Nematomorpha is then compared to that of other Nemathelminthes. The form of the brain and the distribution of perikarya
are derived characters of the Nematomorpha. The existence of an unpaired ventral and an unpaired dorsal nerve cord and the
position of these two cords in epidermal cords are synapomorphies of the Nematomorpha and the Nematoda.
Accepted: 7 July 1996 相似文献
66.
The role of the N-terminus of the extrinsic 33 kDa protein of Photosystem II has been investigated by means of site-directed mutagenesis and cross-linking. Replacement of Asp-9 resulted in a dramatic increase in proteolytic sensitivity leading to the degradation of the protein forming a 31 kDa fragment with an undefined N-terminus. This fragment was unable to restore oxygen evolution. However, the variants of the 33 kDa protein which remained intact could reconstitute oxygen evolution as effectively as the wild-type protein. Cross-linking experiments with a water-soluble carbodiimide revealed that mutagenesis of residue D9 led to the disruption of an intramolecular salt bridge. Therefore we suggest that the N-terminus of the 33 kDa protein is necessary for maintaining the binding ability of the protein to Photosystem II but might not be involved in binding itself. 相似文献
67.
Andreas Christian Dorothee Koberg Holger Preuschoft 《Pal?ontologische Zeitschrift》1996,70(3-4):591-601
The pelvis ofPlateosaurus is examined from a biomechanical point of view. The shape of the acetabulum in particular is analysed in order to determine the range of possible directions of the forces exchanged between femur and pelvis. These forces must have been more or less confined to a sagittal plane. From a quasi-static analysis under consideration of the major hip muscles ofPlateosaurus, a nearly but not fully extended posture of the hindlimbs can be deduced. The hip joints ofPlateosaurus and probably of some other dinosaurs with a narrow biacetabular width were balanced rather by adducting than by abducting muscles. 相似文献
68.
Peter Salzer Gerhard Hebe Andreas Reith Barbara Zitterell-Haid Harald Stransky Katja Gaschler Achim Hager 《Planta》1996,198(1):118-126
Elicitors released from hyphae or cell walls of the ectomycorrhizal fungus Hebeloma crustuliniforme (Bull. ex Fries.) Quél. induced in suspension-cultured cells of Picea abies (L.) Karst. a set of fast reactions: (i) an immediate efflux of Cl– into the medium, followed by a K+ efflux; (ii) an influx of Ca2+ (measured as accumulation of 45Ca2+ in the cells); (iii) a phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein (detectable by 4 min after elicitor application); (iv) an alkalinization of the medium, and (v) a transient synthesis of H2O2. The removal of extracellular Ca2+ by EGTA delayed the elicitor-induced alkalinization. A further reduction of this response could be achieved by TMB-8 an inhibitor of Ca2+ release from intracellular stores. Moreover, the inhibition of protein kinase activity by staurosporine prevented the extracellular alkalinization completely. However, the effectiveness of the elicitors in inducing the extracellular alkalinization was strongly impaired by constitutively secreted enzymes of spruce cells which cleaved the elicitors to inactive fragments. It is suggested that in ectomycorrhizae the efficacy of elicitors released from fungal cell walls is controlled by apoplastic enzymes of the host; the plant itself is able to reduce the activity of fungal elicitors on their way through the plant cell wall. But those elicitors which finally reach the plasma membrane of host cells induce reactions that are similar to the early defense reactions in plant-pathogen interactions.Abbreviations DW
dry weight
- FW
fresh weight
- TMB-8
3,4,5 trimethoxybenzoic acid 8-(diethylamino)-octyl ester
We thank Prof. M. Zenk (Universität München, Germany) for providing spruce cell cultures, and Dr. I. Kottke (Universität Tübingen, Germany) for isolates of Hebeloma crustuliniforme Tü 704. We are also thankful to Dr. W. Mayer (Universität Tübingen) for valuble discussions. This work was supported by Deutsche Forschungsgemeinschaft. B. Zitterell-Haid was financed by Graduiertenkolleg Interaktion in Waldökosystemen (supported by Deutsche Forschungsgemeinschaft) and G. Hebe by a scholarship of the Landesgraduiertenförderungsgesetz. 相似文献
69.
70.