排序方式: 共有122条查询结果,搜索用时 312 毫秒
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Czelleng A Bozso Z Ott PG Besenyei E Varga GJ Szatmari A Kiraly L Klement Z 《Current microbiology》2006,53(4):282-286
Analysis of virulence mechanisms of plant pathogens is often limited by the lack of genetic tools that can be used to identify
genes that are preferentially expressed during their interactions with plants. In the present study, we used the newly constructed
IVET (in vivo expression technique) plasmid pIviGK and the corresponding antibiotic resistance–based selection method to identify genes that encode
pathogenicity factors of the soft rot-causing bacterium Pseudomonas viridiflava. These included pel, the gene encoding pectate lyase, which is responsible for the development of soft rot symptoms. We have also isolated and
characterized the gene mviNpv encoding a putative novel membrane associated virulence factor of P. viridiflava. A mutation in mviNpv was shown to influence motility as well as virulence of P. viridiflava. The mviNpv gene is expressed to a moderate level in LB media and its expression increases under inducing conditions as was shown by
measuring in planta expression dynamics of the fused gfp reporter gene. 相似文献
103.
Ludwiczek S Theurl I Bahram S Schümann K Weiss G 《Journal of cellular physiology》2005,204(2):489-499
Although the recent identification of several genes has extended our knowledge on the maintenance of body iron homeostasis, their tissue specific expression patterns and the underlying regulatory networks are poorly understood. We studied C57black/Sv129 mice and HFE knockout (HFE -/-) variants thereof as a model for hemochromatosis, and investigated the expression of iron metabolism genes in the duodenum, liver, and kidney as a function of dietary iron challenge. In HFE +/+ mice dietary iron supplementation increased hepatic expression of hepcidin which was paralleled by decreased iron regulatory protein (IRP) activity, and reduced expression of divalent metal transporter-1 (DMT-1) and duodenal cytochrome b (Dcytb) in the enterocyte. In HFE -/- mice hepcidin formation was diminished upon iron challenge which was associated with decreased hepatic transferrin receptor (TfR)-2 levels. Accordingly, HFE -/- mice presented with high duodenal Dcytb and DMT-1 levels, and increased IRP and TfR expression, suggesting iron deficiency in the enterocyte and increased iron absorption. In parallel, HFE -/- resulted in reduced renal expression of Dcytb and DMT-1. Our data suggest that the feed back regulation of duodenal iron absorption by hepcidin is impaired in HFE -/- mice, a model for genetic hemochromatosis. This change may be linked to inappropriate iron sensing by the liver based on decreased TfR-2 expression, resulting in reduced circulating hepcidin levels and an inappropriate up-regulation of Dcytb and DMT-1 driven iron absorption. In addition, iron excretion/reabsorption by the kidneys may be altered, which may aggravate progressive iron overload. 相似文献
104.
Chantakru S Wang WC van den Heuvel M Bashar S Simpson A Chen Q Croy BA Evans SS 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(8):4011-4019
Precursors of uterine NK cells home to the uterus during early pregnancy from multiple lymphohemopoietic sources. In mouse uterine tissue, pregnancy markedly up-regulates both L-selectin- and alpha(4) integrin-dependent adhesion pathways for circulating human CD56(bright) cells, the phenotype of human uterine NK cells. Based on roles for these adhesion molecules in lymphocyte homing, we examined effects of pregnancy or the steroid hormones 17beta-estradiol or progesterone on lymphocyte-endothelial interactions in secondary lymphoid tissues and in uterus. From preimplantation gestation day 3, specialized high endothelial venules in peripheral lymph nodes and Peyer's patches supported elevated L-selectin and alpha(4)beta(7) integrin-dependent lymphocyte adhesion under shear throughout pregnancy, as compared with high endothelial venules of virgin or postpartum donors. Squamous endothelium from nonlymphoid tissue was not affected. Pregnancy-equivalent endothelial responses were observed in lymph nodes and Peyer's patches from ovariectomized mice receiving 17beta-estradiol and/or progesterone replacement therapy. Adhesion of human CD56(bright) cells to uteri from pregnant or hormone-treated ovariectomized mice was enhanced through L-selectin- and alpha(4) integrin-dependent mechanisms and involved multiple vascular adhesion molecules including mucosal addressin cell adhesion molecule-1, VCAM-1, and peripheral lymph node addressin. Analysis of Tie2-green fluorescence protein transgenic mice demonstrated that CD56(bright) cells adhered primarily to vascular endothelium within the decidua basalis. Microdomain localization of adhesion involving large clusters of lymphocytes was induced on uteri from natural matings, but not pseudopregnancy. Steroid hormones also had independent effects on L-selectin function in splenic lymphocytes that mimicked physiological stimulation induced by pregnancy or fever-range temperatures. These results provide the first evidence for coordinated, organ-specific, steroid hormone-induced changes in lymphocyte homing mechanisms that could contribute to local and systemic immune responses during pregnancy. 相似文献
105.
Cornet PB Picquet C Lemoine P Osteen KG Bruner-Tran KL Tabibzadeh S Courtoy PJ Eeckhout Y Marbaix E Henriet P 《The Journal of biological chemistry》2002,277(45):42496-42504
The human endometrium is a unique tissue that is periodically shed during menstruation. Although overall triggered by ovarian steroids withdrawal, menstrual induction of matrix metalloproteinases (MMPs) and resulting tissue breakdown are focal responses, pointing to additional local modulators. LEFTY-A, a novel member of the transforming growth factor-beta family identified originally as an endometrial bleeding-associated factor (EBAF), is a candidate for this local control. We measured LEFTY-A and beta-ACTIN mRNA concentration during the menstrual cycle in vivo and found that their ratio was dramatically ( approximately 100-fold) increased at the perimenstrual phase. A similar increase was seen when proliferative explants were cultured for 24 h in the absence of ovarian steroids; this was followed by spontaneous production of proMMP-1, -3, and -9. Both responses were inhibited by progesterone. Moreover, addition of recombinant LEFTY-A to proliferative explants was sufficient to stimulate the expression of proMMP-3 and -7; this response was also blocked by ovarian steroids. Collectively, these data indicate that LEFTY-A may provide a crucial signal for endometrial breakdown and bleeding by triggering expression of several MMPs. Progesterone appears to exert a dual block, upstream by inhibiting LEFTY-A expression and downstream by suppressing its stimulatory effect on MMPs. 相似文献
106.
Mason JM Xu HP Rao SK Leask A Barcia M Shan J Stephenson R Tabibzadeh S 《The Journal of biological chemistry》2002,277(1):407-415
Homeostasis of the extracellular matrix (ECM) of tissues is regulated by controlling deposition and degradation of ECM proteins. The breakdown of ECM is essential in blastocyst implantation and embryonic development, tissue morphogenesis, menstrual shedding, bone formation, tissue resorption after delivery, and tumor growth and invasion. TGF-beta family members are one of the classes of proteins that actively participate in the homeostasis of ECM. Here, we report on the effect of lefty, a novel member of the TGF-beta family, on the homeostasis of extracellular matrix in a fibrosarcoma model. Fibroblastic cells forced to express lefty by retroviral transduction lost their ability to deposit collagen in vivo. This event was associated with down-regulation of the steady-state level of connective tissue growth factor that induces collagen type I mRNA. In addition, lefty transduction significantly decreased collagen type I mRNA expression and simultaneously increased collagenolytic, gelatinolytic, elastolytic, and caseinolytic activities in vivo by the transduced fibroblasts. These findings provide a new insight on the actions of lefty and suggest that this cytokine plays an active role in remodeling of the extracellular matrix in vivo. 相似文献
107.
Kayvan?NajarianEmail author Maryam?Zaheri Ali?A Rad Siamak?Najarian Javad?Dargahi 《BMC bioinformatics》2004,5(1):201
Background
The main goal in analyzing microarray data is to determine the genes that are differentially expressed across two types of tissue samples or samples obtained under two experimental conditions. Mixture model method (MMM hereafter) is a nonparametric statistical method often used for microarray processing applications, but is known to over-fit the data if the number of replicates is small. In addition, the results of the MMM may not be repeatable when dealing with a small number of replicates. In this paper, we propose a new version of MMM to ensure the repeatability of the results in different runs, and reduce the sensitivity of the results on the parameters. 相似文献108.
109.
Rouya Ebrahimi Siamak Rahmanpour Youbert Ghoosta Mahdi Ghaffari 《Archives Of Phytopathology And Plant Protection》2013,46(16):2033-2042
Sclerotinia wilt of sunflower caused by Sclerotinia sclerotiorum (Lib.) De Bary is the major disease of sunflower (Helianthus annuus L.) in Iran. North-western areas of Iran demonstrate the most yield losses through the disease. Development of cultivars with adequate genetic resistance is necessary to avoid these losses. Evaluation of sunflower genotypes varies based on researchers and environmental conditions. Meanwhile, greenhouse tests of the sunflower genotypes are more reliable because of controlled conditions during the assessment activities. To study the reaction of the host plants under controlled conditions, three stem inoculation techniques, including mycelium plug (MP), oxalic acid solution (OAS) and wheat seeds infested (IWS) with Sclerotinia mycelium, were employed. Wounded and non-wounded treatments were used in the experiment to find their effect on the disease progress. Four genotypes, including Ghalami (local variety in market), Confeta, Alstar and Master, were inoculated in this study. The factor was the lesion length to evaluate the effectiveness of different inoculation procedures. The lesion length was measured after 3, 7, 10 and 14 days post inoculation. The analysis of variance demonstrated significant differences between IWS and two other methods (MP and OAS), where the IWS produced the longest lesion lengths. In contrast, the non-significant differences between MP and OAS methods might help researchers to employ the pathogenicity factor (oxalic acid) as an alternative inoculum for their studies. Master variety was the most tolerant genotype among the treatments and its viability was 100% even at 14?days after inoculation and incubation. Interestingly, there was no mortality in all cultivars before 7-day incubations, regardless of resistant or susceptible reactions. 相似文献
110.