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1.
Bacterial biofilms are associated with chronic infections due to their resistance to antimicrobial agents. Staphylococcus
aureus is a versatile human pathogen and can form biofilms on human tissues and diverse medical devices. To identify novel biofilm
inhibitors of S. aureus, the supernatants from a library of 458 Actinomycetes strains were screened. The culture supernatants (1% v/v) of more than 10 Actinomycetes strains inhibited S. aureus biofilm formation by more than 80% without affecting the growth. The culture supernatants of these biofilm-reducing Actinomycetes strains contained a protease (equivalent to 0.1 μg proteinase K ml−1), which both inhibited S. aureus biofilm formation and detached pre-existing S. aureus biofilms. This study suggests that protease treatment could be a feasible tool to reduce and eradicate S. aureus biofilms. 相似文献
2.
Salenko VB Kotnova AP Karpova NN Lyubomirskaya NV Ilyin YV 《Molecular genetics and genomics : MGG》2008,279(5):463-472
Mobile genetic elements constitute a substantial part of eukaryotic genome and play an important role in its organization
and functioning. Co-evolution of retrotransposons and their hosts resulted in the establishment of control systems employing
mechanisms of RNA interference that seem to be impossible to evade. However, “active” copies of endogenous retrovirus gypsy escape cellular control in some cases, while its evolutionary elder “inactive” variants do not. To clarify the evolutionary
relationship between “active” and “inactive” gypsy we combined two approaches: the analysis of gypsy sequences, isolated from G32 Drosophila melanogaster strain and from different Drosophila species of the melanogaster subgroup, as well as the study of databases, available on the Internet. No signs of “intermediate” (between “active” and
“inactive”) gypsy form were found in GenBank, and four full-size G32 gypsy copies demonstrated a convergence that presumably involves gene conversion. No “active” gypsy were revealed among PCR generated gypsy ORF3 sequences from the various Drosophila species indicating that “active” gypsy appeared in some population of D. melanogaster and then started to spread out. Analysis of sequences flanking gypsy variants in G32 revealed their predominantly heterochromatic location. Discrepancy between the structure of actual gypsy sites in G32 and corresponding sequences in database might indicate significant inter-strain heterochromatin diversity.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Ping Su Anders Henriksson Christina Nilsson Hazel Mitchell 《World journal of microbiology & biotechnology》2008,24(9):1837-1842
The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three
probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against
Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both
Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by
24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately.
These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections
caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important
adjuncts to, or alternatives to, conventional antibiotic therapy. 相似文献
4.
N. O. Musa K. Eltom F. Gessler H. Böhnel A. Babiker S. M. El Sanousi 《Folia microbiologica》2010,55(3):211-214
Staphylococcus aureus ssp anaerobius strain S10 was isolated from an outbreak of sheep abscess disease. Sequence of the catalase gene of this strain showed 99
% identity to the catalase gene (katB) sequence of the reference strain (S. aureus ssp. anaerobius strain MVF213) with mismatching of three base pairs. An important substitution located 1036 nucleotides upstream of the initiation
codon from “C” in katB to “T” in the catalase gene of strain S10 originated a stop codon. The deduced protein (345 amino acids) is 105 amino acids
shorter than that of katB. Partial sequence of the catalase gene of other 8 local isolates in addition to another reference strain (DSM 20714/ATCC 35844)
revealed the same mutations in all local (African) strains, whereas the sequence of the reference (European) strain was typical
to that of katB. Sequence of the catalase gene of S. aureus ssp. anaerobius strain S10 was deposited in GenBank under accession no. EU281993. 相似文献
5.
Murat Akkurt Leocir Welter Erika Maul Reinhard Töpfer Eva Zyprian 《Molecular breeding : new strategies in plant improvement》2007,19(2):103-111
Sequence-characterized amplified regions markers (SCARs) were developed from six randomly amplified polymorphic DNA (RAPD)
markers linked to the major QTL region for powdery mildew (Uncinula necator) resistance in a test population derived from the cross of grapevine cultivars “Regent” (resistant) × “Lemberger”(susceptible).
RAPD products were cloned and sequenced. Primer pairs with at least 21 nucleotides primer length were designed. All pairs
were tested in the F1 progeny of “Regent” × “Lemberger”. The SCAR primers resulted in the amplification of specific bands
of expected sizes and were tested in additional genetic resources of resistant and susceptible germplasm. All SCAR primer
pairs resulted in the amplification of specific fragments. Two of the SCAR markers named ScORA7-760 and ScORN3-R produced
amplification products predominantly in resistant individuals and were found to correlate to disease resistance. ScORA7-760,
in particular, is suitable for marker-assisted selection for powdery mildew resistance and to facilitate pyramiding powdery
mildew resistance genes from various sources. 相似文献
6.
de Niederhäusern S Bondi M Messi P Iseppi R Sabia C Manicardi G Anacarso I 《Current microbiology》2011,62(5):1363-1367
In last decade methicillin-resistant Staphylococcus aureus with high level of vancomycin-resistance (VRSA) have been reported and generally the patients with VRSA infection were also
infected with a vancomycin-resistant Enterococcus (VRE). Considering that the high level of vancomycin-resistance in VRSA isolates seems to involve the horizontal transfer
of Tn1546 transposon containing vanA gene from coinfecting VRE strains, the authors have studied the “in vitro” conjugative transfer of this resistance from VanA
enterococci to S. aureus. Out of 25 matings performed combining five vancomycin-resistant enterococci as donors (three Enterococcus faecalis and two Enterococcus faecium), and five S. aureus as recipients, all clinical isolates, two have been successful using E. faecalis as donor. The transfer of vancomycin-resistance was confirmed by vanA gene amplification in both transconjugants and the resistance was expressed at lower levels (MIC 32 μg/ml) in comparison
with the respective VRE donors (MIC > 128 μg/ml). The vancomycin-resistance of trasconjugants was maintained even after subsequent
overnight passages on MSA plates containing subinhibitory levels of vancomycin. This study shows that the vanA gene transfer can be achieved through techniques “in vitro” without the use of laboratory animals employed, in the only similar
experiment previously carried out by other authors, as substrate for the trasconjugant growth. Moreover, in that previous
experiment, contrary to this study, the vancomycin resistant S. aureus trasconjugants were selected on erythromycin agar and not by direct vancomycin agar selection. 相似文献
7.
Nina Rosa F. Castillo Nahla V. Bassil Sugae Wada Barbara M. Reed 《In vitro cellular & developmental biology. Plant》2010,46(3):246-256
Questions often arise concerning the genetic stability of plant materials stored in liquid nitrogen for long time periods.
This study examined the genetic stability of cryopreserved shoot tips of Rubus germplasm that were stored in liquid nitrogen for more than 12 yr, then rewarmed and regrown. We analyzed the genetic stability
of Rubus grabowskii, two blackberry cultivars (“Hillemeyer” and ‘Silvan’), and one raspberry cultivar (“Mandarin”) as in vitro shoots and as field-grown plants. No morphological differences were observed in greenhouse-grown cryopreserved plants when
compared to the control mother plants. In the field, cryopreserved plants appeared similar but were more vigorous than mother
plants, with larger leaves, fruit, and seeds. Single sequence repeats (SSR) and amplified fragment length polymorphism (AFLP)
analyses were performed on shoots immediately after recovery from cryopreservation and on shoots subcultured for 7 mo before
analysis. Ten SSR primers developed from “Marion” and “Meeker” microsatellite-enriched libraries amplified one to 15 alleles
per locus, with an average of seven alleles and a total of 70 alleles in the four genotypes tested. No SSR polymorphisms were
observed between cryopreserved shoots and the corresponding mother plants regardless of subculture. Although no polymorphisms
were detected in shoots analyzed immediately after recovery from cryopreservation, AFLP polymorphisms were detected in three
of the four Rubus genotypes after they were subcultured for 7 mo. Field-grown plants from the polymorphic shoot tips of R. grabowskii and ‘Silvan’ displayed the same AFLP fingerprints as their corresponding mother plants. Only long-cultured in vitro shoot tips displayed polymorphisms in vitro, and they were no longer detected when the plants were grown ex vitro. The transitory nature of these polymorphisms should be carefully considered when monitoring for genetic stability. 相似文献
8.
A method to produce transgenic plants of Vitis rotundifolia was developed. Embryogenic cultures were initiated from leaves of in vitro grown shoot cultures and used as target tissues
for Agrobacterium-mediated genetic transformation. A green fluorescent protein/neomycin phosphotransferase II (gfp/nptII) fusion gene that allowed for simultaneous selection of transgenic cells based on GFP fluorescence and kanamycin resistance
was used to optimize parameters influencing genetic transformation. It was determined that both proembryonal masses (PEM)
and mid-cotyledonary stage somatic embryos (SE) were suitable target tissues for co-cultivation with Agrobacterium as evidenced by transient GFP expression. Kanamycin at 100 mg l−1 in the culture medium was effective in suppression of non-transformed tissue and permitting the growth and development of
transgenic cells, compared to 50 or 75 mg l−1, which permitted the proliferation of more non-transformed cells. Transgenic plants of “Alachua” and “Carlos” were recovered
after secondary somatic embryogenesis from primary SE explants co-cultivated with Agrobacterium. The presence and stable integration of transgenes in transgenic plants was confirmed by PCR and Southern blot hybridization.
Transgenic plants exhibited uniform GFP expression in cells of all plant tissues and organs including leaves, stems, roots,
inflorescences and the embryo and endosperm of developing berries. 相似文献
9.
Giovanni Iapichino Marcello Airò 《In vitro cellular & developmental biology. Plant》2008,44(4):330-337
Multiple shoots were induced on stem segments of an 8-y-old plant of Metrosideros excelsa Sol ex Gaertn. “Parnel”. Axillary shoots produced on uncontaminated explants were excised, segmented, and recultured in the
same medium to increase the stock of shoot cultures. The Murashige and Skoog (MS) medium, augmented with different concentrations
of 2- isopenthenyladenine (2iP) and indole-3-acetic acid (IAA), either singly or in combinations, as potential medium for
shoot multiplication by nodal segments was tested. In the following experiment, equal molar concentrations of four cytokinins
[2iP, kinetin, zeatin, and N
6-benzyladenine (BA)] in combination with equal molar concentrations of three auxins [IAA, α-naphthaleneacetic acid (NAA),
and indole-3-butyric acid (IBA)] were tested for ability to induce axillary shoot development from single-node stem segments.
The highest rate of axillary shoot proliferation was induced on MS agar medium supplemented with 1.96μM 2iP and 1.14μM IAA
after 6 wk in culture. Different auxins (IAA, IBA, and NAA) were tested to determine the optimum conditions for in vitro rooting of microshoots. The best results were accomplished with IAA at 5.71μM (89% rooting) and with IBA at 2.85 or 5.71μM
(86% and 86% rooting, respectively). Seventy and 90 percent of the microshoots were rooted ex vitro in bottom-heated bench (22 ± 2°C) after 2 and 4 wk, respectively. In vitro and ex vitro rooted plantlets were successfully established in soil. 相似文献
10.
Buriev ZT Saha S Shermatov SE Jenkins JN Abdukarimov A Stelly DM Abdurakhmonov IY 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(8):1359-1373
The Gossypium MIC-3 (Meloidogyne Induced Cotton-3) gene family is of great interest for molecular evolutionary studies because of its uniqueness to Gossypium species, multi-gene content, clustered localization, and root-knot nematode resistance-associated features. Molecular evolution
of the MIC-3 gene family was studied in 15 tetraploid and diploid Gossypium genotypes that collectively represent seven phylogenetically distinct genomes. Synonymous (dS) and non-synonymous (dN) nucleotide substitution rates suggest that the second of the two exons of the MIC-3 genes has been under strong positive selection pressure, while the first exon has been under strong purifying selection to
preserve function. Based on nucleotide substitution rates, we conclude that MIC-3 genes are evolving by a birth-and-death process and that a ‘gene amplification’ mechanism has helped to retain all duplicate
copies, which best fits with the “bait and switch” model of R-gene evolution. The data indicate MIC-3 gene duplication events occurred at various rates, once per 1 million years (MY) in the allotetraploids, once per ~2 MY in
the A/F genome clade, and once per ~8 MY in the D-genome clade. Variations in the MIC-3 gene family seem to reflect evolutionary selection for increased functional stability, while also expanding the capacity
to develop novel “switch” pockets for responding to diverse pests and pathogens. Such evolutionary roles are congruent with
the hypothesis that members of this unique resistance gene family provide fitness advantages in Gossypium. 相似文献
11.
Multidrug resistance (MDR) systems are ubiquitously present in prokaryotes and eukaryotes and defend both types of organisms against toxic compounds in the environment. Four families of MDR systems have been described, each family removing a broad spectrum of compounds by a specific membrane-bound active efflux pump. In the present study, at least four MDR systems were identified genetically in the soil bacterium Streptomyces lividans. The resistance genes of three of these systems were cloned and sequenced. Two of them are accompanied by a repressor gene. These MDR gene sequences are found in most other Streptomyces species investigated. Unlike the constitutively expressed MDR genes in Escherichia coli and other gram-negative bacteria, all of the Streptomyces genes were repressed under laboratory conditions, and resistance arose by mutations in the repressor genes.Abbreviations MDR Multidrug resistance 相似文献
12.
13.
Natasa Mitik-Dineva James Wang Vi Khanh Truong Paul Stoddart Francois Malherbe Russell J. Crawford Elena P. Ivanova 《Current microbiology》2009,58(3):268-273
Attachment tendencies of Escherichia coli K12, Pseudomonas aeruginosa ATCC 9027, and Staphylococcus aureus CIP 68.5 onto glass surfaces of different degrees of nanometer-scale roughness have been studied. Contact-angle and surface-charge
measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM)
were employed to characterize substrata and bacterial surfaces. Modification of the glass surface resulted in nanometer-scale
changes in the surface topography, whereas the physicochemical characteristics of the surfaces remained almost constant. AFM
analysis indicated that the overall surface roughness parameters were reduced by 60–70%. SEM, CLSM, and AFM analysis clearly
demonstrates that although E. coli, P. aeruginosa and S. aureus present significantly different patterns of attachment, all of the species exhibited a greater propensity for adhesion to
the “nano-smooth” surface. The bacteria responded to the surface modification with a remarkable change in cellular metabolic
activity, as shown by the characteristic cell morphologies, production of extracellular polymeric substances, and an increase
in the number of bacterial cells undergoing attachment. 相似文献
14.
The objective of this article is to study the effect of 5-aminolevulinic acid (ALA) and enhanced chlorophyll content, antioxidative
enzymes and photosynthesis rate by foliar application of ALA. We evaluated three concentrations (control-distilled water,
T1-50 mg l−1, T2-150 mg l−1, T3-250 mg l−1) of ALA and seven cultivars, “Sanchidaye” (Sa-1), “Lichuandasuomian” (Li-1), “Aijiaohuang” (Ai-1), “Qingyou” No. 4 (Qi-1),
“Aikang” No. 5 (Ak-1), “Hanxiao” (Ha-1) and “Shulv” (Sl-1). “Ak-1” showed strongest response of POD (peroxidase) enzyme activity
(0.4 U g−1 min−1) in 250 mg l−1 ALA solution. The highest CAT (catalase) activity (0.8 U g−1 min−1) after administration of 250 mg l−1 ALA was observed in “Li-1”. Meanwhile, highest (1.42 mg l−1) total chlorophyll content was also observed in “Ak-1”, when leaves were treated in 50 mg l−1 ALA, “Li-1” and “Ai-1” showed strongest response of specific activity of superoxide dismutase (SOD) in 50 mg l−1 and 50 mg l−1 ALA. Two hundred and fifty milligram per milliliter of ALA-treatment significantly improved the net photosynthetic rate. 相似文献
15.
Dagmar Janovská Pavel Klouček Jan Urban Tomáš Vaněk Vojtěch Rada Ladislav Kokoška 《Biologia》2008,63(5):607-609
The antimicrobial activity of the dichloromethane extract from aerial parts of Leuzea carthamoides DC. was tested in vitro against 19 Staphylococcus aureus strains (ATCC 25923, CNCTC Mau 43/60, clinical isolates). The extract was fractionated by column chromatography on silica
gel into six fractions (petroleum ether, toluene, dichloromethane, ethyl acetate, methanol and water). The minimum inhibitory
concentrations (MICs) of the fractions ranged from 64 to 1024 μg/mL. An ethyl acetate fraction (EA 1) with the widest range
of activity inhibited all of the strains with MIC in the range 128–512 μg/mL. This fraction exhibited potent activity against
strains which showed associated resistance to oxacillin, ciprofloxacin and erythromycin. 相似文献
16.
17.
Disanthus cercidifolius Maxim. var. longipes H.T. Chang usually has two inflorescences growing in opposite directions in the axillae, but occasionally three inflorescences
grow paratactically. The typical flowering process could be divided into 4 periods: “Pre-dehiscence”, “Initial dehiscence”, “Full dehiscence” and “Withering”. Both the natural population and the planted population had a flowering peak of 15–35 days after the first flower bloomed.
There were significant differences between the time courses of flowering of the two populations. Out-crossing is the main
breeding system in this species. And autogamy decreases the risk of reproductive failure of this species. The main insect
pollinators of D. cercidifolius var. longipes are Episyrphus balteatus de Geer, Scaptodrosophila coracina Kikkawa and Peng, Polistes olivaceus de Geer, Apis cerana Fabricius, Nezara viridula L. and Coccinella septempunctata L., and so on. Among the insects, S. coracina and E. balteatus are the most important and efficient pollinators, but others are inefficient pollinators. Though wind pollination is not
efficient, it guarantees reproduction when insect pollinators are not available. “Mass flowering” is an adaptive behavior and reproductive strategy of this species, and “few fruiting” could be caused by the lack of pollinators. 相似文献
18.
Several chromosome types have been recognized in Citrus and related genera by chromomycin A3 (CMA) banding patterns and fluorescent in situ hybridization (FISH). They can be used to characterize cultivars and species
or as markers in hybridization and backcrossing experiments. In the present work, characterization of six cultivars of P. trifoliata (“Barnes”, “Fawcett”, “Flying Dragon”, “Pomeroy”, “Rubidoux”, “USDA”) and one P. trifoliata × C. limonia hybrid was performed by sequential analyses of CMA banding and FISH using 5S and 45S rDNA as probes. All six cultivars showed
a similar CMA+ banding pattern with the karyotype formula 4B + 8D + 6F. The capital letters indicate chromosomal types: B, a chromosome
with one telomeric and one proximal band; D, with only one telomeric band; F, without bands. In situ hybridization labeling
was also similar among cultivars. Three chromosome pairs displayed a closely linked set of 5S and 45S rDNA sites, two of them
co-located with the proximal band of the B type chromosomes (B/5S-45S) and the third one co-located with the terminal band
of a D pair (D/5S-45S). The B/5S-45S chromosome has never been found in any citrus accessions investigated so far. Therefore,
this B chromosome can be used as a marker to recognize the intergeneric Poncirus × Citrus hybrids. The intergeneric hybrid analyzed here displayed the karyotype formula 4B + 8D + 6F, with two chromosome types B/5S-45S
and two D/5S-45S. The karyotype formula and the presence of two B/5S-45S chromosomes clearly indicate that the plant investigated
is a symmetric hybrid. It also demonstrates the suitability of karyotype analyses to differentiate zygotic embryos or somatic
cell fusions involving trifoliate orange germplasm.
During the submission of this paper, we analyzed 25 other citrus cultivars with the same methodology and we found that the
chromosome marker reported here can indeed distinguish Poncirus trifoliata from grapefruits, pummelos, and one variegated access of Citrus, besides the previously reported access of limes, limons, citrons, and sweet-oranges. However, among 14 mandarin cultivars,
two of them displayed a single B/5S-45S chromosome, whereas in Citrus hystrix D.C., a far related species belonging to the Papeda subgenus, this chromosome type was found in homozygosis. Since these two mandarin cultivars are probably of hybrid origin,
we assume that for almost all commercial cultivars and species of the subgenus Citrus this B type chromosome is a useful genetic marker. 相似文献
19.
A proteomic approach to understanding the development of multidrug-resistant<Emphasis Type="Italic"> Candida albicans</Emphasis> strains 总被引:1,自引:0,他引:1
Kusch H Biswas K Schwanfelder S Engelmann S Rogers PD Hecker M Morschhäuser J 《Molecular genetics and genomics : MGG》2004,271(5):554-565
Resistance of the pathogenic yeast Candida albicans to the antifungal agent fluconazole is often caused by the overexpression of genes that encode multidrug efflux pumps (CDR1, CDR2, or MDR1). We have undertaken a proteomic approach to gain further insight into the regulatory network controlling efflux pump expression and drug resistance in C. albicans. Three pairs of matched fluconazole-susceptible and resistant clinical C. albicans isolates, in which drug resistance correlated with stable activation of MDR1 or CDR1/2, were analyzed for differences in their protein expression profiles. In two independent, MDR1-overexpressing, strains, additional up-regulated proteins were identified, which are encoded by the YPR127 gene and several members of the IFD (YPL088) gene family. All are putative aldo-keto reductases of unknown function. These proteins were not up-regulated in a fluconazole-resistant strain that overexpressed CDR1 and CDR2 but not MDR1, indicating that expression of the various efflux pumps of C. albicans is controlled by different regulatory networks. To investigate the possible role of YPR127 in the resistance phenotype of the clinical isolates, we constitutively overexpressed the gene in a C. albicans laboratory strain. In addition, the gene was deleted in a C. albicans laboratory strain and in one of the drug-resistant clinical isolates in which it was overexpressed. Neither forced overexpression nor deletion of YPR127 affected the susceptibility of the strains to drugs and other toxic substances, suggesting that the regulatory networks which control the expression of efflux pumps in C. albicans also control genes involved in cellular functions not related to drug resistance.Communicated by D. Y. Thomas 相似文献
20.
Acacia catechu, commonly known as catechu, cachou and black cutch is an important medicinal plant and an economically important forest tree.
The methanolic extract of this plant was found to have antimicrobial activities against six species of pathogenic and non-pathogenic
microorganisms: Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. The maximum zone of inhibition (20 mm) was found to be exhibited against S. aureus. For this organism the minimum bactericidal concentration (MBC) of the crude extract was 1,000 μg/ml. The extract was found
to be equally effective against gram positive and gram negative bacteria. The antimicrobial activity of the extract was found
to be decreased during purification. The chemical constituents of organic plant extracts were separated by thin layer chromatography
(TLC) and the plant extracts were purified by column chromatography and were further identified by Gas chromatography–mass
selection (GC–MS) analysis. The composition of A. catechu extract had shown major components of terpene i.e. camphor (76.40%) and phytol (27.56%) along with other terpenes in minor
amounts which are related with their high antibacterial and antifungal properties. 相似文献