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991.
Ekaterina S Bozhokina Olga A Tsaplina Tatiana N Efremova Ludmila V Kever Ilya V Demidyuk Sergey V Kostrov Thomas Adam Yan Yu Komissarchik Sofia Yu Khaitlina 《Cell biology international》2011,35(2):111-118
Earlier, we have shown that spontaneously isolated non‐pathogenic bacteria Serratia grimesii and Serratia proteamaculans invade eukaryotic cells, provided that they synthesize thermolysin‐like metalloproteases ECP32/grimelysin or protealysin characterized by high specificity towards actin. To address the question of whether the proteases are active players in entry of these bacteria into host cells, in this work, human larynx carcinoma Hep‐2 cells were infected with recombinant Escherichia coli expressing grimelysin or protealysin. Using confocal and electron microscopy, we have found that the recombinant bacteria, whose extracts limitedly cleaved actin, were internalized within the eukaryotic cells residing both in vacuoles and free in cytoplasm. The E. coli‐carrying plasmids without inserts of grimelysin or protealysin gene did not enter Hep‐2 cells. Moreover, internalization of non‐invasive E. coli was not observed in the presence of protealysin introduced into the culture medium. These results are consistent with the direct participation of ECP32/grimelysin and protealysin in entry of bacteria into the host cells. We assume that ECP32/grimelysin and protealysin mediate invasion being injected into the eukaryotic cell and that the high specificity of the enzyme towards actin may be a factor contributed to the bacteria internalization. 相似文献
992.
Tatiana de Campos Paula Rodrigues Oblessuc Danilo Augusto Sfor?a Juliana Morini Kupper Cardoso Renata Moro Baroni Adna Cristina Barbosa de Sousa S��rgio Augusto Morais Carbonell Alisson Fernando Chioratto Antonio Augusto Franco Garcia Luciana Benchimol Rubiano Anete Pereira de Souza 《Molecular breeding : new strategies in plant improvement》2011,27(4):549-560
The genetic linkage map for the common bean (Phaseolus vulgaris L.) is a valuable tool for breeding programs. Breeders provide new cultivars that meet the requirements of farmers and consumers, such as seed color, seed size, maturity, and growth habit. A genetic study was conducted to examine the genetics behind certain qualitative traits. Growth habit is usually described as a recessive trait inherited by a single gene, and there is no consensus about the position of the locus. The aim of this study was to develop a new genetic linkage map using genic and genomic microsatellite markers and three morphological traits: growth habit, flower color, and pod tip shape. A mapping population consisting of 380 recombinant F10 lines was generated from IAC-UNA × CAL143. A total of 871 microsatellites were screened for polymorphisms among the parents, and a linkage map was obtained with 198 mapped microsatellites. The total map length was 1865.9 cM, and the average distance between markers was 9.4 cM. Flower color and pod tip shape were mapped and segregated at Mendelian ratios, as expected. The segregation ratio and linkage data analyses indicated that the determinacy growth habit was inherited as two independent and dominant genes, and a genetic model is proposed for this trait. 相似文献
993.
Kochetkova TV Rusanov II Pimenov NV Kolganova TV Lebedinsky AV Bonch-Osmolovskaya EA Sokolova TG 《Extremophiles : life under extreme conditions》2011,15(3):319-325
Carbon monoxide (CO) is one of the common gaseous compounds found in hot volcanic environments. It is known to serve as the
growth substrate for a number of thermophilic prokaryotes, both aerobic and anaerobic. The goal of this work was to study
the process of anaerobic transformation of CO by microbial communities inhabiting natural thermal environments: hot springs
of Uzon Caldera, Kamchatka. The anaerobic microbial community of Treshchinny Spring (80°C, pH 6.5) was found to exhibit two
peaks of affinity for CO (K
S1 = 54 nM and K
S2 = 1 μM). The actual rate of anaerobic CO transformation by the microbial community of this spring, calculated after obtaining
the concentration dependence curve and extrapolated to the natural concentration of CO dissolved in the hot spring water (20 nM),
was found to be 120 μmol l−1 of sediment day−1. In all the hot springs studied, more than 90% of the carbon of 14CO upon anaerobic incubation was recovered as 14CO2. From 1 to 5% of 14CO was transformed to volatile fatty acids (VFA). The number of microorganisms capable of anaerobic CO oxidation determined
by dilution-to-extinction method reached 106 cells ml−1 of sediment. CO-transforming anaerobic thermophilic microorganisms isolated from the springs under study exhibited hydrogenogenic
type of CO oxidation and belonged to the bacterial genera Carboxydocella and Dictyoglomus. These data suggest a significant role of hydrogenogenic carboxydotrophic prokaryotes in anaerobic CO transformation in Uzon
Caldera hot springs. 相似文献
994.
Tishchenko G Simůnek J Bartoňová H Dušková J Dohnálek J Ponomareva E Tennikova T 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(22):2175-2178
Membrane ultrafiltration (UF) was used in sample preparation of the culture fluids of the human intestinal bacterium Clostridium paraputrificum strain J4 containing seven extracellular chitinolytic isoenzymes (38-90 kDa). The subsequent filtration of the bacteria-free supernatants was carried out through Millipore membranes with cut-off 100 and 30 kDa for separation of undigested components of the culture medium and bacterial metabolites with molecular weight higher and lower than that of the target enzymes. The chitinolytic enzymes, which were the minor components in the culture fluids, were concentrated at UF as well. The aim of the research consisted in evaluation of the effect of component composition of bacteria-free supernatants and the chemical nature of membrane active layer on partial fractionation of the chitinolytic enzymes, their recovery in retentates and purification degree. On the basis of the obtained experimental results, the sample preparation procedure of the culture fluids of C. paraputrificum J4 was established to be used further in chromatographic separations of the chitinolytic enzymes. 相似文献
995.
Fluctuating asymmetry (FA) represents small, random variation from symmetry and it has been used as an indicator of plant
quality and susceptibility to herbivory. In this study, the effects of FA on the responses of distinct herbivore species belonging
to several guilds were examined along an environmental gradient in south Florida. This approach was chosen because it relies
on a multi-species approach to the study of fluctuating asymmetry and patterns of herbivory between and within plants along
an environmental gradient of salinity and plant stress. To examine differences in FA between and within plant communities,
seven plant species were investigated. Four of these plants were coastal species and three species occurred in upland communities.
Levels of FA were assessed before herbivory and plants were followed for the whole herbivory season in 2006. Coastal plants
exhibited significantly higher salt concentration, higher percentage of asymmetric leaves and higher asymmetry levels than
upland plants. Herbivore abundance varied widely amongst the seven species studied, but quantitative syntheses of our results
indicated significant and positive responses of insect herbivores to leaf asymmetry: insects were 25.11% more abundant on
more asymmetric plants and stronger effects of asymmetry were observed for leaf miners compared to gall-formers. As demonstrated
by other recent studies, FA might be used as a reliable stress indicator, leading to similar responses of insect herbivores
to variation in leaf symmetry. 相似文献
996.
Schijman AG Bisio M Orellana L Sued M Duffy T Mejia Jaramillo AM Cura C Auter F Veron V Qvarnstrom Y Deborggraeve S Hijar G Zulantay I Lucero RH Velazquez E Tellez T Sanchez Leon Z Galvão L Nolder D Monje Rumi M Levi JE Ramirez JD Zorrilla P Flores M Jercic MI Crisante G Añez N De Castro AM Gonzalez CI Acosta Viana K Yachelini P Torrico F Robello C Diosque P Triana Chavez O Aznar C Russomando G Büscher P Assal A Guhl F Sosa Estani S DaSilva A Britto C Luquetti A Ladzins J 《PLoS neglected tropical diseases》2011,5(1):e931
Background
A century after its discovery, Chagas disease still represents a major neglected tropical threat. Accurate diagnostics tools as well as surrogate markers of parasitological response to treatment are research priorities in the field. The purpose of this study was to evaluate the performance of PCR methods in detection of Trypanosoma cruzi DNA by an external quality evaluation.Methodology/Findings
An international collaborative study was launched by expert PCR laboratories from 16 countries. Currently used strategies were challenged against serial dilutions of purified DNA from stocks representing T. cruzi discrete typing units (DTU) I, IV and VI (set A), human blood spiked with parasite cells (set B) and Guanidine Hidrochloride-EDTA blood samples from 32 seropositive and 10 seronegative patients from Southern Cone countries (set C). Forty eight PCR tests were reported for set A and 44 for sets B and C; 28 targeted minicircle DNA (kDNA), 13 satellite DNA (Sat-DNA) and the remainder low copy number sequences. In set A, commercial master mixes and Sat-DNA Real Time PCR showed better specificity, but kDNA-PCR was more sensitive to detect DTU I DNA. In set B, commercial DNA extraction kits presented better specificity than solvent extraction protocols. Sat-DNA PCR tests had higher specificity, with sensitivities of 0.05–0.5 parasites/mL whereas specific kDNA tests detected 5.10−3 par/mL. Sixteen specific and coherent methods had a Good Performance in both sets A and B (10 fg/µl of DNA from all stocks, 5 par/mL spiked blood). The median values of sensitivities, specificities and accuracies obtained in testing the Set C samples with the 16 tests determined to be good performing by analyzing Sets A and B samples varied considerably. Out of them, four methods depicted the best performing parameters in all three sets of samples, detecting at least 10 fg/µl for each DNA stock, 0.5 par/mL and a sensitivity between 83.3–94.4%, specificity of 85–95%, accuracy of 86.8–89.5% and kappa index of 0.7–0.8 compared to consensus PCR reports of the 16 good performing tests and 63–69%, 100%, 71.4–76.2% and 0.4–0.5, respectively compared to serodiagnosis. Method LbD2 used solvent extraction followed by Sybr-Green based Real time PCR targeted to Sat-DNA; method LbD3 used solvent DNA extraction followed by conventional PCR targeted to Sat-DNA. The third method (LbF1) used glass fiber column based DNA extraction followed by TaqMan Real Time PCR targeted to Sat-DNA (cruzi 1/cruzi 2 and cruzi 3 TaqMan probe) and the fourth method (LbQ) used solvent DNA extraction followed by conventional hot-start PCR targeted to kDNA (primer pairs 121/122). These four methods were further evaluated at the coordinating laboratory in a subset of human blood samples, confirming the performance obtained by the participating laboratories.Conclusion/Significance
This study represents a first crucial step towards international validation of PCR procedures for detection of T. cruzi in human blood samples. 相似文献997.
Klimke W O'Donovan C White O Brister JR Clark K Fedorov B Mizrachi I Pruitt KD Tatusova T 《Standards in genomic sciences》2011,5(1):168-193
The promise of genome sequencing was that the vast undiscovered country would be mapped out by comparison of the multitude of sequences available and would aid researchers in deciphering the role of each gene in every organism. Researchers recognize that there is a need for high quality data. However, different annotation procedures, numerous databases, and a diminishing percentage of experimentally determined gene functions have resulted in a spectrum of annotation quality. NCBI in collaboration with sequencing centers, archival databases, and researchers, has developed the first international annotation standards, a fundamental step in ensuring that high quality complete prokaryotic genomes are available as gold standard references. Highlights include the development of annotation assessment tools, community acceptance of protein naming standards, comparison of annotation resources to provide consistent annotation, and improved tracking of the evidence used to generate a particular annotation. The development of a set of minimal standards, including the requirement for annotated complete prokaryotic genomes to contain a full set of ribosomal RNAs, transfer RNAs, and proteins encoding core conserved functions, is an historic milestone. The use of these standards in existing genomes and future submissions will increase the quality of databases, enabling researchers to make accurate biological discoveries. 相似文献
998.
999.
Amaratunga C Lopera-Mesa TM Brittain NJ Cholera R Arie T Fujioka H Keefer JR Fairhurst RM 《PloS one》2011,6(4):e14798
Background
In Africa, infant susceptibility to Plasmodium falciparum malaria increases substantially as fetal hemoglobin (HbF) and maternal immune IgG disappear from circulation. During the first few months of life, however, resistance to malaria is evidenced by extremely low parasitemias, the absence of fever, and the almost complete lack of severe disease. This resistance has previously been attributed in part to poor parasite growth in HbF-containing red blood cells (RBCs). A specific role for maternal immune IgG in infant resistance to malaria has been hypothesized but not yet identified.Methods and Findings
We found that P. falciparum parasites invade and develop normally in fetal (cord blood, CB) RBCs, which contain up to 95% HbF. However, these parasitized CB RBCs are impaired in their binding to human microvascular endothelial cells (MVECs), monocytes, and nonparasitized RBCs – cytoadherence interactions that have been implicated in the development of high parasite densities and the symptoms of malaria. Abnormal display of the parasite''s cytoadherence antigen P. falciparum erythrocyte membrane protein-1 (PfEMP-1) on CB RBCs accounts for these findings and is reminiscent of that on HbC and HbS RBCs. IgG purified from the plasma of immune Malian adults almost completely abolishes the adherence of parasitized CB RBCs to MVECs.Conclusions
Our data suggest a model of malaria protection in which HbF and maternal IgG act cooperatively to impair the cytoadherence of parasitized RBCs in the first few months of life. In highly malarious areas of Africa, an infant''s contemporaneous expression of HbC or HbS and development of an immune IgG repertoire may effectively reconstitute the waning protective effects of HbF and maternal immune IgG, thereby extending the malaria resistance of infancy into early childhood. 相似文献1000.
Recent clinical findings support the notion that the progressive deterioration of cholesterol homeostasis is a central player in Alzheimer's disease (AD). Epidemiological studies suggest that high midlife plasma total cholesterol levels are associated with an increased risk of AD. This paper reports the plasma cholesterol concentrations, cognitive performance, locomotor activity and neuropathological signs in a murine model (transgenic mice expressing apoB100 but knockout for the LDL receptor [LDLR]) of human familial hypercholesterolaemia (FH). From birth, these animals have markedly elevated LDL-cholesterol and apolipoprotein B100 (apoB100) levels. These transgenic mice were confirmed to have higher plasma cholesterol concentrations than wild-type mice, an effect potentiated by aging. Further, 3-month-old transgenic mice showed cholesterol (total and fractions) concentrations considerably higher than those of 18-month-old wild-type mice. The hypercholesterolaemia of the transgenic mice was associated with a clear locomotor deficit (as determined by rotarod, grip strength and open field testing) and impairment of the episodic-like memory (determined by the integrated memory test). This decline in locomotor activity and cognitive status was associated with neuritic dystrophy and/or the disorganization of the neuronal microtubule network, plus an increase in astrogliosis and lipid peroxidation in the brain regions associated with AD, such as the motor and lateral entorhinal cortex, the amygdaloid basal nucleus, and the hippocampus. Aortic atherosclerotic lesions were positively correlated with age, although potentiated by the transgenic genotype, while cerebral β-amyloidosis was positively correlated with genetic background rather than with age. These findings confirm hypercholesterolaemia as a key biomarker for monitoring mild cognitive impairment, and shows these transgenic mice can be used as a model for cognitive and psycho-motor decline. 相似文献