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81.
A total of 1257 Actinomycetes strains, the majority of which of the albus, griseus and globisporus series, were isolated from 345 samples from the rhizosphere of various plants and soils. According to these observations the cultivation of the soil is not of paramount importance for the quantitative and species composition of the Actinomycetes. The determination of the antibacterial spectrum shows that 45% of the isolated strains have antagonistic properties with respect to Gram positive, Gram negative, acid fast bacteria, yeastlike fungi and moulds. 相似文献
82.
Moten Dzhemal Kolchakova Desislava Todorov Krasimir Mladenova Tsvetelina Dzhambazov Balik 《The protein journal》2022,41(2):315-326
The Protein Journal - Allergic diseases are a socially significant problem of global importance. The number of people suffering from pollen allergies has increased dramatically in recent decades.... 相似文献
83.
The thermo-sensitivity of two new pea (Pisum sativum L.) cultivars—Afila (mutant in the gene transforming leaves into mustaches) and Ranen (mutant for early ripening)—as compared
to the control cultivar Pleven-4 to either low (4 °C, T4) or high temperature (38 °C, T38) was investigated by means of chlorophyll (Chl) fluorescence kinetics. The low temperature treatment decreased the photosynthetic
activity, measured via a decline of the Chl fluorescence decrease ratios RFd690 and RFd735, and this was mainly due to a decline of the Chl fluorescence decrease parameter Fd and maximum Chl fluorescence Fm. In the new cv. Ranen the RFd ratios at first decreased and increased again after 24-h exposure to 4 °C, indicating its good acclimation ability to low
temperature. The cold-induced changes in the photosynthetic performance of all cultivars were reversed after transferring
plants back to 23 °C for 48 h. In the Chl and carotenoid (Car) contents no or little changes occurred during the T4 treatment, except for a slight but clear increase of the ratio Chl a/b and a decrease in the ratio Chl/Car. In contrast to this, the T38 treatment for 72 h decreased the RFd ratios more strongly than the T4 exposure did. In fact, an irreversible injury of the photosynthetic apparatus was caused in the control pea cv. Pleven-4
by a 48-h T38 exposure and for the new cv. Afila after a 72-h T38 exposure. In contrast, the cv. Ranen was less and little sensitive to the T38 exposure. In the heat-sensitive cvs. Pleven-4 and Afila, the decrease in RFd values at T38 was associated with a strong decline of the Chl a+b and total Car contents. The Chl a+b decline could also be followed via an increase of the Chl fluorescence ratio F690/F735. Parallel to this, a strong decline of Chl a/b from ca. 3.0 (range 2.85–3.15) to ca. 1.9 (range 1.85–1.95) occurred indicating a preferential decline of the Chl a-pigment proteins but not of the Chl a/b-pigment protein LHC2. In the relatively heat-tolerant cv. Ranen, however, the ratio Chl a/b declined only partially. After the T4 treatment the stress adaptation index Ap was higher in cv. Ranen than in controls and reached in heat-treated Ranen plants
almost the starting value indicating a cold and heat stress hardening of the treated plants. The Chl fluorescence parameters
and pigment contents were influenced by T38 and T4 treatments in various ways indicating that the mechanisms of low and high temperature injury of the photosynthetic apparatus
are different. The new cv. Ranen exhibited a cross tolerance showing a fairly good acclimation ability to both T4 and T38, hence it is a very suitable plant for outdoor growth and for clarification of the acclimation mechanisms to unfavourable
temperatures. 相似文献
84.
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87.
We describe an altered mobility for acetylated histone isoforms in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoforms of histones H3 and H4 with a higher acetylation degree have a slightly faster electrophoretic mobility. Since acetylation neutralizes the positive charge of the epsilon-amino group of lysine, without significantly changing the molecular mass of the protein, the acetylation-dependent mobility shift could be explained by the increase of the net negative charge of the SDS-histone complexes. A possible consequence of this differential mobility for the acetylation site determination by protein microsequencing from SDS gels is discussed. 相似文献
88.
Improvement of posttranslational bottlenecks in the production of penicillin amidase in recombinant Escherichia coli strains 总被引:4,自引:0,他引:4
Ignatova Z Mahsunah A Georgieva M Kasche V 《Applied and environmental microbiology》2003,69(2):1237-1245
Using periplasmic penicillin amidase (PA) from Escherichia coli ATCC 11105 as a model recombinant protein, we reviewed the posttranslational bottlenecks in its overexpression and undertook attempts to enhance its production in different recombinant E. coli expression hosts. Intracellular proteolytic degradation of the newly synthesized PA precursor and translocation through the plasma membrane were determined to be the main posttranslational processes limiting enzyme production. Rate constants for both intracellular proteolytic breakdown (k(d)) and transport (k(t)) were used as quantitative tools for selection of the appropriate host system and cultivation medium. The production of mature active PA was increased up to 10-fold when the protease-deficient strain E. coli BL21(DE3) was cultivated in medium without a proteinaceous substrate, as confirmed by a decrease in the sum of the constants k(d) and k(t). The original signal sequence of pre-pro-PA was exchanged with the OmpT signal peptide sequence in order to increase translocation efficiency; the effects of this change varied in the different E. coli host strains. Furthermore, we established that simultaneous coexpression of the OmpT pac gene with some proteins of the Sec export machinery of the cell resulted in up to threefold-enhanced PA production. In parallel, we made efforts to increase PA flux via coexpression with the kil gene (killing protein). The primary effects of the kil gene were the release of PA into the extracellular medium and an approximately threefold increase in the total amount of PA produced per liter of bacterial culture. 相似文献
89.
Georgieva R Moya S Hin M Mitlöhner R Donath E Kiesewetter H Möhwald H Bäumler H 《Biomacromolecules》2002,3(3):517-524
Polyelectrolyte microcapsules (PEMCs) have been prepared by coating red blood cells with the polyelectrolytes poly(styrenesulfonate), poly(allylamine hydrochloride), and dextran sulfate applying the layer-by-layer technique with subsequent dissolution of the core. The capsule permeability for human serum albumin (HSA) was studied as a function of the ionic strength and pH by means of confocal microscopy. PEMCs produced with dextran sulfate and poly(allylamine hydrochloride) show a significant increase in permeability for HSA at salt concentrations over 1 mM. For PEMCs prepared with poly(styrenesulfonate) and poly(allylamine hydrochloride) the limiting salt concentration is 5 mM. No pH dependence for permeation was observed. A correlation between the permeation and adsorption of HSA on the PEMC walls was investigated. Finally, a mechanism for the permeability, combining electrostatic interactions, and the presence of pores in the polymer layers is presented confirmed by the considerable increase of permeation of charged molecules in the presence of salt and the permeation of neutral molecules regardless of the ionic strength. 相似文献
90.
T Belenkaya A Soldatov E Nabirochkina I Birjukova S Georgieva P Georgiev 《Genetics》1998,150(2):687-697