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Populations Isolated (population + isolated)

Distribution by Scientific Domains

Life Sciences	55%
Medical Sciences	44%

Selected Abstracts

Different portions of the maize root system host Burkholderia cepacia populations with different degrees of genetic polymorphism

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2000
Luigi Chiarini
In order to acquire a better understanding of the spatial and temporal variations of genetic diversity of Burkholderia cepacia populations in the rhizosphere of Zea mays, 161 strains were isolated from three portions of the maize root system at different soil depths and at three distinct plant growth stages. The genetic diversity among B. cepacia isolates was analysed by means of the random amplified polymorphic DNA (RAPD) technique. A number of diversity indices (richness, Shannon diversity, evenness and mean genetic distance) were calculated for each bacterial population isolated from the different root system portions. Moreover, the analysis of molecular variance ( amova) method was applied to estimate the genetic differences among the various bacterial populations. Our results showed that, in young plants, B. cepacia colonized preferentially the upper part of the root system, whereas in mature plants, B. cepacia was mostly recovered from the terminal part of the root system. This uneven distribution of B. cepacia cells among different root system portions partially reflected marked genetic differences among the B. cepacia populations isolated along maize roots on three distinct sampling occasions. In fact, all the diversity indices calculated indicated that genetic diversity increased during plant development and that the highest diversity values were found in mature maize plants, in particular in the middle and terminal portions of the root system. Moreover, the analysis of RAPD patterns by means of the amova method revealed highly significant divergences in the degree of genetic polymorphism among the various B. cepacia populations. [source]

Chemokine receptor CXCR3 expression in inflammatory bowel disease

INFLAMMATORY BOWEL DISEASES, Issue 4 2001
Yu-Hong Yuan
Abstract CD4+ T lymphocytes in the lamina propria (LP) of the gut play a central role in the immune response in inflammatory bowel disease (IBD). CXCR3 is a chemokine receptor expressed on activated T lymphocytes, and a key component for the recruitment of T helper (Th1) effector cells to the site of inflammation. To determine if CXCR3 is involved in localization of T cells to the gut in IBD patients, we investigated the expression of CXCR3 on CD4+ T lymphocytes in the LP and in the submucosa of resection specimens from 51 IBD patients and 15 control patients. Positive cells were microscopically scored using a semiquantitative analysis on a five-point scale. We found that CD4+ T cells, CXCR3+ cells, and CD4+CXCR3+ T cells in the LP were slightly increased in both IBD groups compared with control non-IBD specimens. In addition, CD4+ and CXCR3+ cells in the submucosa were significant increased in the CD group compared with the control group. CD4+ and CXCR3+ expression was not statistically different between CD and UC. Flow cytometry was used to analyze the percentage of CXCR3+ cells within the CD4+ T-cell population isolated from biopsy specimens and peripheral blood from IBD patients and control patients. There was no difference in the percentage of CD4+CXCR3+ cells between the different groups in the gut as well as in the circulation. These results suggest that CD4+CXCR3+ T cells migrate to the normal and inflamed intestinal mucosa, indicating a role in maintaining normal gut homeostasis. The selective expression of CXCR3+ cells in the submucosa of CD patients might also indicate that these cells play a role in inflammation. [source]

Seasonal changes in suppressive capacity of CD4+ CD25+ T cells from patients with hayfever are allergen-specific and may result in part from expansion of effector T cells among the CD25+ population

CLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2009
A. E. Anderson
Summary Background Suppression of allergen-stimulated peripheral blood CD4+ CD25, effector T cells by CD4+ CD25+ regulatory T cells obtained from subjects with allergic rhinoconjunctivitis is reduced during the pollen season when compared with out of season. Objective We examined possible explanations for this effect of seasonal pollen exposure on suppression of allergen responses. Methods CD4+ CD25, and CD4+ CD25+ T cells were isolated from blood obtained from 44 volunteers with allergic rhinoconjunctivitis during and out of the UK grass pollen season. Co-cultures were performed with grass pollen extract and house dust mite (HDM) to examine allergen specificity. The frequency of IL-5 and IL-10 producing cells was determined by ELISPOT and the expression of T cell activation markers and the CD25+ regulatory T cell-associated transcription factor Foxp3 were examined. Lactic acid stripping of IgE was used to determine IgE dependence of T cell responses. Results The seasonal reduction in suppression by CD4+ CD25+ T cells was confirmed and was shown to be allergen specific because suppression of HDM-stimulated cultures was not affected significantly. The CD4+ CD25+ population contained IL-5 and IL-10 producing cells but increases in their frequencies with seasonal pollen exposure were not significant. Both activation marker and Foxp3 expression increased during the pollen season. IgE stripping reduced CD4+ and CD4+ CD25, T cell responses to allergen, but had no effect on suppression by CD4+ CD25+ T cells. Conclusion The seasonal reduction in suppression of grass pollen-stimulated effector T cells by CD4+ CD25+ T cells is allergen specific and cannot be explained by increased IgE-facilitated allergen presentation. We suggest that changes in the proportion of effector to regulatory T cells among the CD25+ population isolated may partially explain these findings, and that trafficking to the site of allergic disease may reduce allergen-specific regulatory T cell numbers in peripheral blood. [source]

Different portions of the maize root system host Burkholderia cepacia populations with different degrees of genetic polymorphism

Analysis of non- Saccharomyces yeast populations isolated from grape musts from Sicily (Italy)

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008
D.P. Romancino
Abstract Aims:, The aim of this study was to identify the non- Saccharomyces yeast populations present in the grape must microflora from wineries from different areas around the island of Sicily. Methods and Results:, Yeasts identification was conducted on 2575 colonies isolated from six musts, characterized using Wallerstein Laboratory (WL) nutrient agar, restriction analysis of the amplified 5·8S-internal transcribed spacer region and restriction profiles of amplified 26S rDNA. In those colonies, we identified 11 different yeast species originating from wine musts from two different geographical areas of the island of Sicily. Conclusions:, We isolated non- Saccharomyces yeasts and described the microflora in grape musts from different areas of Sicily. Moreover, we discovered two new colony morphologies for yeasts on WL agar never previously described. Significance and Impact of the Study:, This investigation is a first step in understanding the distribution of non- Saccharomyces yeasts in grape musts from Sicily. The contribution is important as a tool for monitoring the microflora in grape musts and for establishing a new non- Saccharomyces yeast collection; in the future, this collection will be used for understanding the significance of these yeasts in oenology. [source]

Phylogeography of Douglas-fir based on mitochondrial and chloroplast DNA sequences: testing hypotheses from the fossil record

MOLECULAR ECOLOGY, Issue 9 2010
PAUL F. GUGGER
Abstract The integration of fossil and molecular data can provide a synthetic understanding of the ecological and evolutionary history of an organism. We analysed range-wide maternally inherited mitochondrial DNA and paternally inherited chloroplast DNA sequence data with coalescent simulations and traditional population genetic methods to test hypotheses of population divergence generated from the fossil record of Douglas-fir (Pseudotsuga menziesii), an ecologically and economically important western North American conifer. Specifically, we tested (i) the hypothesis that the Pliocene orogeny of the Cascades and Sierra Nevada caused the divergence of coastal and Rocky Mountain Douglas-fir varieties; and (ii) the hypothesis that multiple glacial refugia existed on the coast and in the Rocky Mountains. We found that Douglas-fir varieties diverged about 2.11 Ma (4.37 Ma,755 ka), which could be consistent with a Pliocene divergence. Rocky Mountain Douglas-fir probably resided in three or more glacial refugia. More variable molecular markers would be required to detect the two coastal refugia suggested in the fossil record. Comparison of mitochondrial DNA and chloroplast DNA variation revealed that gene flow via pollen linked populations isolated from seed exchange. Postglacial colonization of Canada from coastal and Rocky Mountain refugia near the ice margin at the Last Glacial Maximum produced a wide hybrid zone among varieties that formed almost exclusively by pollen exchange and chloroplast DNA introgression, not seed exchange. Postglacial migration rates were 50,165 m/year, insufficient to track projected 21st century warming in some regions. Although fossil and genetic data largely agree, each provides unique insights. [source]

Identification of triploid trophoblast cells in peripheral blood of a woman with a partial hydatidiform molar pregnancy

PRENATAL DIAGNOSIS, Issue 13 2001
I. J. van Wijk
Abstract In a woman with a partial hydatidiform molar pregnancy with 69,XXY karyotype, the presence of male fetal cells of trophoblastic origin was demonstrated in maternal blood by X/Y-chromosome specific PCR and by immunostaining combined with FISH on two cell populations isolated from maternal blood. Blood was obtained three weeks prior to the detection of fetal demise, at 13 weeks' gestation. Results were confirmed on formalin-fixed paraffin-embedded molar tissue, removed at 16 weeks' gestational age for therapeutic reasons. The results indicate that both plasma and cells from maternal peripheral blood might be useful for non-invasive prenatal diagnosis of fetal aneuploidies, as described in the current case with a partial molar pregnancy. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Dendritic Cell Subset Ratio in Peripheral Blood Correlates with Successful Withdrawal of Immunosuppression in Liver Transplant Patients

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2003
George V. Mazariegos
Human dendritic cell (DC) subsets appear to play distinct roles in the induction and regulation of immune responses. While monocytoid DC (DC1) induce T-helper (Th) 1-type responses, plasmacytoid DC (DC2) have been reported to selectively induce Th2 responses. In blood, their precursors (p) can be identified as HLA-DR+ lineage, cells that are further characterized as CD11c+ CD123,/lo (IL-3R,,/lo) (pDC1) or as CD11c, CD123hi (pDC2) by rare event, flow cytometric analysis. We compared the incidences of pDC1 and pDC2 in peripheral blood mononuclear cell populations isolated from normal healthy controls and from 3 groups of clinically stable liver transplant patients. Group A had been successfully withdrawn from immunosuppression, whereas group B were undergoing prospective drug weaning and on minimal anti-rejection therapy. In group C, drug withdrawal had either failed or never been attempted and patients were on maintenance immunosuppression. Assessment of DC subsets and the pDC2 : pDC1 ratio showed good intra-and interassay reproducibility. Compared with patients in group C, those in groups A and B demonstrated a significantly higher relative incidence of pDC2 and a lower incidence of pDC1 , similar to those values observed in normal healthy controls. Moreover, the pDC2 : pDC1 ratio was significantly higher in patients undergoing (successful) weaning and in those off immunosuppression compared with patients on maintenance immunosuppression. [source]

Regulation of the interferon-, production induced by RNA-containing immune complexes in plasmacytoid dendritic cells

ARTHRITIS & RHEUMATISM, Issue 8 2009
Maija-Leena Eloranta
Objective Interferon-, (IFN,) is produced in several autoimmune diseases, including systemic lupus erythematosus (SLE), and may be important in their pathogenesis. We undertook this study to investigate how IFN, production induced by RNA-containing immune complexes (ICs) in plasmacytoid dendritic cells (PDCs) is regulated. Methods Normal PDCs purified from peripheral blood mononuclear cells (PBMCs) were cocultivated with other cell populations isolated from healthy individuals or SLE patients. IFN, production was induced by RNA-containing ICs, which consisted of anti-RNP autoantibodies and U1 small nuclear RNP particles, and the effects of prostaglandin E2 (PGE2), reactive oxygen species (ROS), or the cytokines IFN,2b, granulocyte,macrophage colony-stimulating factor (GM-CSF), interleukin-10 (IL-10), or tumor necrosis factor , (TNF,) were explored. Results Monocytes inhibited IFN, production by PDCs in PBMC cultures, while natural killer (NK) cells were stimulatory. The monocytes had little effect on IFN, production by pure PDCs but inhibited its stimulation by NK cells. Monocytes from SLE patients were less inhibitory. Exposure of PBMCs or PDCs to IFN,2b/GM-CSF increased their IFN, production. RNA-containing ICs caused production of ROS, PGE2, and TNF,, especially in monocytes. These mediators and IL-10 suppressed IFN, production in PBMC cultures, with ROS and PGE2 also inhibiting IFN, production by purified PDCs. Inhibition by all of these agents, except for ROS, was abolished by IFN,2b/GM-CSF. The inhibitory effect of monocytes was significantly counteracted by the ROS scavengers serotonin and catalase. Conclusion IFN, production induced by RNA-containing ICs in PDCs is regulated by a network of interactions between monocytes, NK cells, and PDCs, involving several pro- and antiinflammatory molecules. This should be considered when designing and applying new therapies. [source]