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11.
In-vitro-grown cells of Mucuna pruriens, immobilized in calcium-alginate gels, were able to transform the precursor L-tyrosine into L-dihydroxyphenylalanine (L-DOPA). After the immobilization in alginate the plant cells released 90% of the produced L-DOPA into the medium; supplementation of the medium with calcium inhibited both the transformation of L-tyrosine into L-DOPA and the release of L-DOPA into the medium. Continuous illumination of the beads had a slight beneficial effect on the synthesis of L-DOPA. A simple production medium for the transformation of L-tyrosine into L-DOPA was designed. This medium contained only sucrose and sodium chloride as osmotic stabilizers, a low concentration of calcium chloride for stabilization of the alginate beads, and L-tyrosine as the precursor. 相似文献
12.
The phenylpropanoid derived lignan podophyllotoxin, occurring inPodophyllum species, is used as a starting compound for the chemical synthesis of the antitumour agents etoposide (VP-16-213) and teniposide (VM-26). At present, the availability of this lignan becomes increasingly limited. As an alternative source, cell cultures originating fromPodophyllum hexandrum Royle were initiated. Analysis of the cell extracts using different HPLC systems as well as TLC, indicated the presence of podophyllotoxin. After prepurification of the extracts by means of ITLC, the identity was confirmed by mass spectrometric analysis. Dark-grown cultures accumulated considerable higher amounts of podophyllotoxin in comparison with the light-grown cultures. 相似文献
13.
Identification of a widely distributed 90-kDa glycoprotein that is homologous to the Hermes-1 human lymphocyte homing receptor 总被引:9,自引:0,他引:9
S T Pals F Hogervorst G D Keizer T Thepen E Horst C C Figdor 《Journal of immunology (Baltimore, Md. : 1950)》1989,143(3):851-857
Homing of recirculating lymphocytes from the blood into the lymphoid tissues is mediated by 90-kDa homing receptors on the lymphocyte cell surface, allowing selective binding to specialized endothelium lining high endothelial venules. This study describes two novel mAb, NKI-P1 and NKI-P2, directed against functional epitopes of a human lymphocyte homing receptor, gp90. Biochemical studies demonstrated that these antibodies recognize a 90-kDa glycoprotein which is similar to the Ag recognized by the mAb Hermes-1. This notion was confirmed by immunohistochemical studies showing identical reaction patterns. Furthermore, it was observed that NKI-P1 and NKI-P2 blocked adhesion of lymphocytes to high endothelial venules. Immunohistochemical, immunofluorescence, and immunoprecipitation studies revealed that gp90 is widely expressed on hemopoietic cells including lymphocytes, macrophages/dendritic cells, myeloid cells, and erythrocytes. The gp90 is also expressed on a number of nonhemopoietic cells such as endothelial cells, certain epithelial cells, and fibroblasts. In addition to its expression on normal cells, gp90 is present on a spectrum of tumor cell lines of lymphoid, monocytic, epithelial, glial, and melanocytic origin. In addition to the 90-kDa product, the antibodies immunoprecipitate several polypeptides in the range of 120 to 200 kDa. Interestingly, it was observed that certain mamma tumor cell-line cells lack the 90-kDa polypeptide indicating the heterogeneous expression of the molecules recognized by the antibodies. These results indicate that the 90-kDa glycoprotein homologues of the Hermes-1 human lymphocyte homing receptor are expressed on hemopoietic tissues as well as on a number of nonhemopoietic tissues and tumor cell lines. Although the function of these molecules in nonlymphoid cells is presently unknown, they might play a role in cell-cell or cell-matrix adhesion. 相似文献
14.
Wim van Uden Niesko Pras Esther M. Vossebeld Jos N. M. Mol Theo M. Malingré 《Plant Cell, Tissue and Organ Culture》1990,20(2):81-87
Cell suspension cultures of Linum flavum L., routinely grown on a NAA-containing medium, accumulated low levels of the phenylpropanoid-derived lignan 5-methoxypodophyllotoxin (5-MPT), up to 0.004% on a dry weight basis. Feeding experiments with the precursor L-phenylalanine resulted in a 3–5-fold increase in 5-MPT levels, but caused the levels of PAL activity to fall. Treatment of the cultures with the elicitor Nigeran, either alone or in combination with phenylalanine, caused the 5-MPT production to cease, even though PAL activity was rapidly enhanced by these treatments. Transfer of the cultures to NAA-free medium resulted in a 40–50 fold higher level of 5-MPT accumulation, the PAL activity levels being lowered compared to the routinely grown cells. With these more differentiated cultures, phenylalanine feeding and elicitor treatment, both on its own and in combination with the precursor, had no effect on 5-MPT production, even though the PAL activity levels were higher than in the untreated cells. It can be concluded that in lignan-accumulating cultures of L. flavum, PAL activity is nearly always detectable and seems to show a reciprocal relationship with 5-MPT accumulation.Abbreviations 5-MPT
5-methoxypodophyllotoxin
- PAL
phenylalanine ammonia lyase (EC 4:3:1.5)
- NAA
naphthaleneacetic acid 相似文献
15.
Johannes H. P. Hackstein Theo A. van Alen 《Evolution; international journal of organic evolution》1996,50(2):559-572
It has been assumed that the feeding habits of vertebrates predispose the variety of intestinal differentiations and the composition of the microbial biota living in their intestinal tracts. Consequently, the presence of methanogenic bacteria in the various differentiations of the large intestine and the foregut of herbivorous vertebrates had been attributed primarily to the existence of anaerobic habitats and the availability of carbon dioxide and hydrogen originating from the fermentative microbial digestion of plant-based diets. However, Australian ratites, many murids, and several New World primates lack methanogens, despite their intestinal differentiations and their vegetarian feeding habits. Crocodiles, giant snakes, aardvarks, and ant-eaters on the other hand release significant amounts of methane. A determination of methane emissions by 253 vertebrate species confirmed that competence for intestinal methanogenic bacteria is shared by related species and higher taxa, irrespective of different feeding habits. In “methanogenic” branches of the evolutionary tree, a variety of differentiations of the large intestine evolved and, in some cases, differentiations of the foregut. In contrast, the lack of competence for methanogens in chiropterans/insectivores and carnivores apparently has precluded the evolution of specialized fermenting differentiations of the digestive tract. Our observations reveal that the presence of intestinal methanogenic bacteria is under phylogenetic rather than dietary control: competence for intestinal methanogenic bacteria is a plesiomorphic (primitive-shared) character among reptiles, birds, and mammals. This competence for methanogenic bacteria has been crucial for the evolution of the amniotes. 相似文献
16.
17.
The sphinctozoid sponge generaFania Senowbari-Daryan 1990 andSpica Termier &Termier 1977 are preoccupied.Fania is replaced byFanthalamia nom. nov. andSpica by the younger synonymFistulispongia Termier &Termier 1977. The invalid subfamily name FaniinaeSenowbari-Daryan 1990 is replaced by Fanthalamiinae n. subfam. The invalid family and subfamily names SpicidaeTermier &Termier 1977 and SpicinaeSenowbari-Daryan 1990 respectively are replaced by FistulispongiidaeTermier atTermier 1977 and FistulispongiinaeSenowbari-Daryan 1990. The generaWaagenium de Laubenfels 1957 andCatubria Merla 1931 were previously overlooked.Waagenium DeLaubenfels 1957 is a younger synonym ofColospongia Laube 1865. The position ofCatubria Merla 1931 is uncertain. Most probablyCatubria is an alga. 相似文献
18.
Anke J. de Jong Theo Hendriks Ellen A. Meijer Maarten Penning Fiorella L. Schiavo Mario Terzi Ab van Kammen Sacco C. de Vries 《Genesis (New York, N.Y. : 2000)》1995,16(4):332-343
At the nonpermissive temperature, somatic embryos of the temperature-sensitive (ts) carrot (Daucus carota L.) cell variant ts11 only proceed beyond the globular embryo stage in the presence of medium conditioned by wild-type cells. The causative component in the conditioned medium has been identified as an acidic 32 kD endochitinase. An antiserum raised against the 32 kD chitinase detected this protein in culture medium from ts11 embryo cultures grown at the permissive temperature as well as at the nonpermissive temperature. No difference in biochemical characteristics or in effect on ts11 embryo development could be detected between the 32 kD chitinase purified from wild-type cultures and the chitinase from ts11 cultures grown at the permissive or at the nonpermissive temperature. Compared to the amount present in a ts11 embryo culture at the permissive temperature, a reduction in the amount of 32 kD chitinase was observed during the temperature-sensitive period at the nonpermissive temperature. These results imply that the arrested embryo phenotype of ts11 is not the result of a structural difference in its 32 kD chitinase, but is the result of a transient decrease in the amount of 32 kD chitinase present. Morphological observations indicate that the ts11 phenotype is pleiotropic and also affects the cell wall of nonembryogenic cells. © 1995 Wiley-Liss, Inc. 相似文献
19.
20.
Thomas Schnyder Peter Tittmann Hanspeter Winkler Heinz Gross Theo Wallimann 《Journal of structural biology》1995,114(3)
Octamers of mitochondrial creatine kinase (Mi-CK) wore modified with the thiol-specific reagents N-ethylmaleimide or the gold-coupled derivative, maleidoyl undecagold. The kinetics of inhibition of the Mi-CK catalysis was shown to be comparable for both reagents, suggesting that the large gold cluster complex is accessible to the reactive cysteines. SDS-PAGE analysis revealed that two of eight cysteines per Mi-CK monomer were labeled with maleidoyl undecagold with a similar affinity for the functional maleimide group. Gel exclusion chromatography of labeled molecules showed that the octameric structure of Mi-CK was preserved after thiol modification. Freeze-dried gold-labeled octamers visualized by electron microscopy under cryoconditions were enhanced in contrast and showed a well-preserved fourfold symmetry of the end-on view, Image analysis of gold-labeled Mi-CK exhibited an averaged end-on view with four strong contrast signals located at the periphery of the notamer, whereas the center of the molecule remained electron translucent. We conclude that the two cysteine residues per monomer labeled with maleidoyl undecagold are located at the octamer's perimeter and we discuss the possible role of these reactive cysteines in enzyme catalysis. 相似文献