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1.
Anna Sotirova Tatyana Avramova Stoyanka Stoitsova Irina Lazarkevich Vera Lubenets Elena Karpenko Danka Galabova 《Current microbiology》2012,65(5):534-541
The antimicrobial properties of methyl (MTS) and ethyl (ETS) esters of thiosulfonic acid alone and in combination with rhamnolipid-biosurfactant (RL) have been characterized for their ability to disrupt the normal physiological functions of living pathogens. Bactericidal and fungicidal activities of MTS and ETS and their combination with rhamnolipid were demonstrated on strains of Pseudomonas aeruginosa, Bacillus subtilis, Alcaligenes faecalis, and Rhizopus ngtricans. It was found that the combination of rhamnolipid and thiosulfonic esters has a synergistic effect leading to decreasing of bactericidal and fungicidal concentrations of MTS and ETS. More extensively was studied the effect of rhamnolipid on the lipid composition of B. subtilis bacterial membrane. To our knowledge, in this article is reported for the first time a remarkable increase of negatively charged phospholipid cardiolipin in the presence of rhamnolipid. The capacity of RL as a surface-active substance was confirmed by scanning electron microscopy (SEM). The occurrence of surface infolds and blebs on B. subtilis shown by SEM, was not accompanied by changes in membrane permeability tested by a live/dead viability staining for fluorescence microscopy. When RL was applied in combination with MTS, a dramatic permeability shift for propidium iodide was observed in vegetative cells. 相似文献
2.
A study of bacterial surface oligosaccharides were investigated among
different strains of Neisseria gonorrhoeae to correlate structural features
essential for binding to the MAb 2C7. This epitope is widely expressed and
conserved in gonococcal isolates, characteristics essential to an effective
candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared
by a modification of the hot phenol-water method from which de-O-acetylated
LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and
ES-MSnin a triple quadrupole and an ion trap mass spectrometer,
respectively. Previously documented natural heterogeneity was apparent from
both LOS and OS preparations which was admixed with fragments induced by
hydrazine and mild acid treatment. Natural heterogeneity was limited to
phosphorylation and antenni extensions to the alpha-chain. Mild acid
hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic
linkage of lipid A. OS structures were determined by collisional and
resonance excitation combined with MS and multistep MSn which provided
sequence information from both neutral loss, and nonreducing terminal
fragments. A comparison of OS structures, with earlier knowledge of MAb
binding, enzyme treatment, and partial acid hydrolysis indicates a generic
overlapping domain for 2C7 binding. Reoccurring structural features include
a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the
nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc
(gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the
central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain),
moiety is required although extensions to this residue appear unnecessary.
相似文献
3.
Aglika Edreva Violeta Sotirova Iordanka D. Georgieva Elisaveta Stoimenova Rositza Rodeva Nevena Bogatzevska 《Acta Physiologiae Plantarum》2000,22(3):274-277
In the present work the responses of β-glucosidase in leaves of tomato plants subjected to various stress factors of both
pathogenic (fungi, bacteria, viruses) and abiotic origin (heat shock) were studied. Biochemical and cytochemical methods were
applied. It was established that an increase of β-glucosidase activity is induced uniquely by fungal pathogens. The cytochemical
tests confirm the finding. Hence, the conclusion can be drawn that β-glucosidase response is a specific character of fungal
pathogenesis in tomato; probably, the enzyme is involved in plant — fungi recognition. The data are in accordance with our
previous results on tobacco and wheat — stress stimuli systems. 相似文献
4.
RNA interference is a widely used tool for analysis of gene function in mammalian cells. Stable knockdown of specific target genes can be maintained in cell lines and live organisms using vector-based delivery of short hairpins (shRNAs) driven by RNA polymerase III promoters. Here we describe a vector incorporating the human 7SK promoter for shRNA-mediated gene silencing in the P19 embryonic carcinoma stem cell line. Our preliminary experiments with the 7SK shRNA expression vector indicated that its activity could be hindered by random genomic integration. In order to counter this inhibitory mechanism, we inserted a matrix-attached region sequence to generate an episomal vector system. We compared the effects of insertion versus exclusion of the MAR sequence on the shRNA-mediated gene-specific silencing of the beta-tubulin III and Cyclophilin A genes. While the MAR sequence is not strongly correlated with the episomal status of the expression vector, our studies indicate that inclusion of the MAR element significantly enhances the stability of shRNA-mediated gene silencing in the P19 stem cells. 相似文献
5.
Zagorska NA Shtereva LA Kruleva MM Sotirova VG Baralieva DL Dimitrov BD 《Plant cell reports》2004,22(7):449-456
We present data on the morphological, cytological, biochemical and genetic characteristics of tomato regenerants obtained through anther culture. As a result of induced androgenesis, more than 6,000 rooted regenerants were developed that differed both from the donor plants and among each other with respect to habitus and leaf, flower and inflorescence morphology. Cytological analysis revealed a great variability in chromosome number in the cells of the regenerated plants. While most of the regenerants were mixoploid, the majority of the cells had a haploid chromosome number. R1 and R2 progenies were tested for their resistance to Clavibacter michiganense subsp. michiganense (Cmm 7). Some of the regenerants were resistant to the pathogen. A biochemical analysis of fruit from R3 and R4 plants showed a higher content of dry matter, sugars and vitamin C in the regenerant plants obtained from the hybrids than in those from the cultivars and control plants. The values of the parameters of hybrid regenerants grown in the greenhouse were about 1.5-fold higher than those of the hybrid regenerants grown in the field, and this trend is clearly expressed in all of the hybrid regenerants. The results obtained suggest that induced androgenesis and gametoclonal variation may be used as an additional tool to create a large range of new forms. The application of the latter in breeding programs would accelerate the development of tomato lines and varieties that would be more productive, disease-resistant, highly nutritive and flavour-acceptable.Abbreviations
BAP
N6-Benzylaminopurine
-
Cmm
Clavibacter michiganense subsp. michiganense
-
cfu
Colony-forming units
-
GA
3
Gibberellic acid
-
IBA
Indole-3-butyric acid
-
ms
Male sterility
-
PDA
Potato dextrose agar
Communicated by H. Lörz 相似文献
6.
7.
Violeta Georgieva Sotirova Nevena Stojanova Bogatsevska 《Acta Physiologiae Plantarum》2000,22(3):256-259
Thirty six tomato wild species accessions of the subgenera Eulycopersicon and Eriopersicon of the genus Lycopersicon were inoculated with race T1 and T3 of Xanthomonas vesicatoria by vaccum infiltration method. Degree of diseases was evaluated by scale of 0 to 4. It was established that some accessions
showed low degree of disease to race T1 and others to race T3. LA 2623 indicated very low degree of disease to race T1 and
was immune in inoculation with T3. LA 386 and LA 1297 manifested hypersensitive reaction to both races and PI 127826 to race
T3 only. The accessions possessing low degree of disease or hypersensitive reaction to race T1 and race T3 are new promising
sources of resistance to Xanthomonas vesicatoria. 相似文献
8.
Iordanka Georgieva Aglika Edreva Rossitza Rodeva Violeta Sotirova Elisaveta Stoimenova 《Acta Physiologiae Plantarum》2000,22(3):281-284
The metabolic changes in tomato fruits and seeds separately infected with cucumber mosaic virus, Pseudomonas syringae pv. tomato or Botrytis cinerea were investigated cytochemically. The changes of peroxidase (E.C. 1.11.1.7) and β-glucosidase (E.C. 3.2.1.21) were investigated
biochemically as well. Tomato fruits were involved in the study because of their high economic value. Tomato seeds were investigated
since they have been used most extensively as a model system for studying the physiology and biochemistry of seed development.
The diseases caused by the pathogens under study are of special importance for yield reduction in tomato. The three pathogens
provoked local changes in the activities of enzymes under study that affect the infected pericarp tissues and neighboring
seeds. It was established non-specific and specific responses. The non-specific responses of invaded tissues were expressed
as a local enhancement of peroxidase activity in both pericarp tissues and seeds as well as a decrease in activities of: i. enzymes taking part in aerobic and anaerobic respiration, ii. hydrolases esterase and acid phosphatase involved in the basic metabolism as well as an enhancement of their activities in
neighboring tissues. Furthermore, it was observed an enhancement of α-galactosidase activity in infected area was observed.
The specific responses depending on the type of the pathogen consisted in an enhancement of glucose-6-phosphate dehydrogenase
activity by virus infection and an increase of β-glucosidase activity by fungal invasion. 相似文献
9.
The potential of biosurfactant PS to permeabilize bacterial cells of Pseudomonas aeruginosa, Escherichia coli, and Bacillus subtilis on growing (in vivo) and resting (in vitro) cells was studied. Biosurfactant was shown to have a neutral or detrimental effect
on the growth of Gram-positive strains, and this was dependent on the surfactant concentration. The growth of Gram-negative
strains was not influenced by the presence of biosurfactant in the media. Cell permeabilization with biosurfactant PS was
shown to be more effective with B. subtilis resting cells than with Pseudomonas aeruginosa. Scanning-electron microscopy observations showed that the biosurfactant PS did not exert a disruptive action on resting
cells such that it was detrimental to the effect on growing cells of B. subtilis. Low critical micelle concentrations, tender action on nongrowing cells, and neutral effects on the growth of microbial strains
at low surfactant concentrations make biosurfactant PS a potential candidate for application in different industrial fields,
in environmental bioremediation, and in biomedicine. 相似文献
10.
In this study, the effect of rhamnolipid biosurfactant produced by Pseudomonas fluorescens on bacterial strains, laboratory strains, and isolates from industrial wastewater was investigated. It was shown that biosurfactant,
depending on the concentration, has a neutral or detrimental effect on the growth and protein release of model Gram (+) strain
Bacillus subtilis 168. The growth and protein release of model Gram (−) strain Pseudomonas aeruginosa 1390 was not influenced by the presence of biosurfactant in the medium. Rhamnolipid biosurfactant at the used concentrations
supported the growth of some slow growing on hexadecane bacterial isolates, members of the microbial community. Changes in
cell surface hydrophobicity and permeability of some Gram (+) and Gram (−) isolates in the presence of rhamnolipid biosurfactant
were followed in experiments in vitro. It was found that bacterial cells treated with biosurfactant became more or less hydrophobic
than untreated cells depending on individual characteristics and abilities of the strains. For all treated strains, an increase
in the amount of released protein was observed with increasing the amount of biosurfactant, probably due to increased cell
permeability as a result of changes in the organization of cell surface structures. The results obtained could contribute
to clarify the relationships between members of the microbial community as well as suggest the efficiency of surface properties
of rhamnolipid biosurfactant from Pseudomonas fluorescens making it potentially applicable in bioremediation of hydrocarbon-polluted environments. 相似文献