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1.
A procedure was developed which allows the large-scale isolation of root hairs from seedlings of Pisum sativum . L. cvs. Kleine Rheinländerin and Rosa Krone. The method may yield up to 50 g fresh weight of root hairs per 3.104 seedlings. In a modified form considerable amounts of root hair material may be harvested, even after incubation of the roots in aqueous solutions. Thus, detailed biochemical studies on the root hair system have become feasible.
The occurrence of specific proteins in membrane fractions of P. sativum root hairs was demonstrated as follows: Incubation of root hairs in situ with 3-azidonaphthalene-2,7-disulfonate – a strongly anionic, photoactivated fluorescent marker – followed by gel electrophoresis of membrane fractions showed the presence of root-hair specific proteins which, since the system was intact, suggests that they are on the outer surface of the cells. 相似文献
The occurrence of specific proteins in membrane fractions of P. sativum root hairs was demonstrated as follows: Incubation of root hairs in situ with 3-azidonaphthalene-2,7-disulfonate – a strongly anionic, photoactivated fluorescent marker – followed by gel electrophoresis of membrane fractions showed the presence of root-hair specific proteins which, since the system was intact, suggests that they are on the outer surface of the cells. 相似文献
2.
Rhizobium japonicum 61-A-101 and its bacteroids catabolize phenol and p-hydroxybenzoate. With phenol as a carbon source, utilization started only after a prolonged lag phase while p-hydroxybenzoate was almost instantancously metabolized. Succinate, which supports rapid growth of Rhizobium japonicum, completely repressed respication of phenol; the oxidation of p-hydroxybenzoate was partially inhibited. Pyruvate, supporting slower growth than succinate, retarded the onset of phenol consumption but did not affect its maximum rate.Catabolite repression of phenol utilization by succinate appears to be a characteristic feature of rhizobia. In Pseudomonas putida which also actively metabolizes phenol, succinate had no effect on phenol utilization. 相似文献
3.
Cytokeratin expression in simple epithelia 总被引:10,自引:0,他引:10
Valentino Romano Mechthild Hatzfeld Thomas M. Magin Ralf Zimbelmann Werner W. Franke Gernot Maier Herwig Ponstingl 《Differentiation; research in biological diversity》1986,30(3):244-253
To study the regulation of the expression of cytokeratins characteristic of simple epithelia, i.e., human cytokeratins nos. 7, 8, 18, and 19, we prepared several cDNA clones coding for these proteins and their bovine counterparts. In the present study, we describe a cDNA clone of the mRNA coding for human cytokeratin no. 18, which was isolated from an expression library using the monoclonal antibody, KG 8.13. This clone (756 nucleotides, excluding the polyA portion), encodes approximately one-half of the mRNA (approximately 1.4 kb), identifies one mRNA band in Northern-hybridization blots, and specifically selects one mRNA species coding for cytokeratin no. 18, as demonstrated by translation in vitro. Comparison of the deduced amino acid sequence--confirmed by direct amino-acid-sequence analyses of some polypeptide fragments produced by cleavage with cyanogen bromide--indicated that cytokeratin no. 18 is a member of the acidic (type I) subfamily of cytokeratins. It has only limited sequence homologies in common with other intermediate-sized filament proteins, and these are essentially restricted to certain domains of the alpha-helical rod portion. The carboxyterminal tail sequence does not contain glycine-rich elements, thus distinguishing this cytokeratin from those acidic (type I) cytokeratins that are characterized by this feature. The similarities and differences between cytokeratin no. 18 and previously described epidermal cytokeratins are discussed in relation to the differences in the stability of the complexes which this cytokeratin forms with basic (type II) cytokeratins, as well as in relation to possible functional differences of cytokeratins in simple and stratified epithelia. 相似文献
4.
A 395 bp fragment located downstream from the soybean heat shock geneGmhsp 17.6-L exhibits several characteristics of scaffold attachment region (SAR) sequences. It contains matrix consensus elements, a topoisomerase II binding sequence and it associates with the isolated nuclear scaffold of soybeanin vitro. Chimaeric genes containing the SARL fragment either at one side (5 or 3) or at both sides of a heat shock promoter-regulated -glucuronidase reporter gene were constructed. A five-to nine-fold increase of heat-inducible -glucuronidase activity was observed in transgenic tobacco plants containing constructs with SARL fragments either at both sides or with at least one SARL copy located upstream from the reporter gene. The gene copy number is positively correlated with the level of heat-inducible reporter gene activity in these. plants but positional effects are not entirely eliminated. Thus, SAR sequences may potentially be used to increase gene expression, via as yet unknown mechanisms, and to reduce adverse effects on the expression of multiple gene copies in transgenic plants. 相似文献
5.
Fibronectin (FN) turnover and turnover changes induced by the anticancer drug Adriamycin (ADR) were measured in human mesangial cells (HMC) in vitro. HMC cultures synthesize cellular FN (2.2+-0.3% of totalprotein synthesis; n = 12) which is secreted and incorporated into a fibrillar extracellular matrix (ECM). A 24 hr incubation of HMC with ADR (0.5–5 g/ml) resulted in an accumulation of FN in the culture medium, with a maximum increase following 5 pglml(7.3+-2.3pg/cell vs. controls: 4.4+-1.9pg/cell; n= 10). Correspondingly, radioactively labeled immunoprecipitable FN was increased in a dosage-dependent manner in the culture medium up to 50% vs. controls. The incorporation of radioactively labeled FN into ECM was significantly increased following 2 g ADR/ml. In accordance, immunofZuorescence staining revealed an expansion ofpericellular FNfibers in cultures exposed to 2 g ADR/ml. Concomitant with the accumulation of extracelhlar FN, radioactively labeled FN in the cells was reduced by 22%. Qualitative characterization of FN patterns revealed a diminished number of degradation products in the culture medium ofADR-treated HMC. These data suggest thatADR interferes with the turnover of FN secreted by HMC in vitro in such a way that FN accumulates extracellularly. This in turn leads to a reduced FN synthesis. These findings are compatible with a loss of urinary FN degradation products accompanying the onset ofproteinuria in ADR-treated rats.Abbreviations ADR
adriamycin
- BSA
bovine serum albumin
- DTT
dithiothreitol
- ECM
extracellular matrix
- EDTA
ethylenediamine tetraacetic acid disodium salt
- ELISA
enzyme-linked immunosorbent assay
- FCS
fetal calf serum
- FITC
fluorescein isothiocyanate
- FN
fibronectin
- HMC
human mesangial cell
- PBS
phosphate buffered saline
- PMSF
phenylmethylsulfonyl fluoride
- SDS
sodium dodecyl sulfate
- SDS-PAGE
SDS-polyacrylamide gel electrophoresis 相似文献
6.
Mechthild Geyer Tassilo Feuerer Guido Benno Feige 《Plant Systematics and Evolution》1984,145(1-2):41-54
The secondary lichen products of 31 specimens of theRhizocarpon superficiale group are examined by high performance liquid chromatography (HPLC). At 260 nm 13 different compounds have been detected. 6 of them are well-known lichen acids which occur in nearly all the species; but proportions are different and constant for each species. An analytical key is added.
Beitrag I einer Publikationsreihe. 相似文献
7.
8.
Summary Experiments with black locust (Robinia pseudoacacia L.) seedlings grown under strictly controlled laboratory conditions indicated that the availability of nitrate has a marked impact on nitrogen fixation. When nitrate concentrations were very low, both nodulation and seedling growth were impaired, whereas nitrate concentrations high enough to promote plant growth strongly inhibited symbiotic nitrogen fixation. When nitrate was added to the growth medium after infection, nodulation and nitrogen fixation of the seedlings decreased. This effect was even more marked when nitrate was applied before infection with rhizobia. Higher nitrogen concentrations also reduced nodule number and nodule mass when applied simultaneously with the infecting bacteria. The contribution of symbiotic nitrogen fixation to black locust shoot mass by far exceeded its effects on shoot length and root mass. When nitrate availability was very low, specific nitrogen fixation (i. e. nitrogenase activity per nodule wet weight) was improved with increasing nitrogen supply, but rapidly decreased with higher nitrogen concentrations. 相似文献
9.
Ifey Alio Mirja Gudzuhn Pablo Pérez García Dominik Danso Marie Charlotte Schoelmerich Uwe Mamat Ulrich E. Schaible J?rg Steinmann Daniel Yero Isidre Gibert Thomas A. Kohl Stefan Niemann Matthias I. Gr?schel Johanna Haerdter Thomas Hackl Christel Vollstedt Mechthild B?meke Richard Egelkamp Rolf Daniel Anja Poehlein Wolfgang R. Streit 《Applied and environmental microbiology》2020,86(24)
10.
Nitrogen is an essential macronutrient for plant growth. Following uptake from the soil or assimilation within the plant, organic nitrogen compounds are transported between organelles, from cell to cell and over long distances in support of plant metabolism and development. These translocation processes require the function of integral membrane transporters. The review summarizes our current understanding of the molecular mechanisms of organic nitrogen transport processes, with a focus on amino acid, ureide and peptide transporters. 相似文献