排序方式: 共有304条查询结果,搜索用时 15 毫秒
11.
Merve Sasmaz Bunyamin Akgül Derya Yıldırım 《International journal of phytoremediation》2016,18(1):69-76
This study investigated mercury (Hg) uptake and transport from the soil to different plant parts by documenting the distribution and accumulation of Hg in the roots and shoots of 12 terrestrial plant species, all of which grow naturally in surface soils of the Gumuskoy Pb-Ag mining area. Plant samples and their associated soils were collected and analyzed for Hg content by ICP-MS. Mean Hg values in the soils, roots, and shoots of all plants were 6.914, 460, and 206 µg kg?1, respectively and lower than 1. The mean enrichment factors for the roots (ECR) and shoots (ECS) of these plants were 0.06 and 0.09, respectively and lower than 1. These results show that the roots of the studied plants prevented Hg from reaching the aerial parts of the plants. The mean translocation factor (TLF) was 1.29 and higher than 1. The mean TLF values indicated that all 12 plant species had the ability to transfer Hg from the roots to the shoots but that transfer was more efficient in plants with higher ECR and ECS. Therefore, these plants could be useful for the biomonitoring of environmental pollution and for rehabilitating areas contaminated by Hg. 相似文献
12.
13.
Coker-Gurkan Ajda Bulut Derya Genc Recep Arisan Elif-Damla Obakan-Yerlikaya Pınar Palavan-Unsal Narcin 《Molecular biology reports》2019,46(1):355-369
Molecular Biology Reports - Autocrine growth hormone (GH) signaling is a promoting factor for breast cancer via triggering abnormal cell growth, proliferation, and metastasis, drug resistance.... 相似文献
14.
Andre Bazzone Laura Tesmer Derya Kurt H. Ronald Kaback Klaus Fendler M. Gregor Madej 《The Journal of biological chemistry》2022,298(2)
Bacterial transporters are difficult to study using conventional electrophysiology because of their low transport rates and the small size of bacterial cells. Here, we applied solid-supported membrane–based electrophysiology to derive kinetic parameters of sugar translocation by the Escherichia coli xylose permease (XylE), including functionally relevant mutants. Many aspects of the fucose permease (FucP) and lactose permease (LacY) have also been investigated, which allow for more comprehensive conclusions regarding the mechanism of sugar translocation by transporters of the major facilitator superfamily. In all three of these symporters, we observed sugar binding and transport in real time to determine KM, Vmax, KD, and kobs values for different sugar substrates. KD and kobs values were attainable because of a conserved sugar-induced electrogenic conformational transition within these transporters. We also analyzed interactions between the residues in the available X-ray sugar/H+ symporter structures obtained with different bound sugars. We found that different sugars induce different conformational states, possibly correlating with different charge displacements in the electrophysiological assay upon sugar binding. Finally, we found that mutations in XylE altered the kinetics of glucose binding and transport, as Q175 and L297 are necessary for uncoupling H+ and d-glucose translocation. Based on the rates for the electrogenic conformational transition upon sugar binding (>300 s−1) and for sugar translocation (2 s−1 − 30 s−1 for different substrates), we propose a multiple-step mechanism and postulate an energy profile for sugar translocation. We also suggest a mechanism by which d-glucose can act as an inhibitor for XylE. 相似文献
15.
Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献
16.
Tanriover G Kayisli UA Demir R Pestereli E Karaveli S Demir N 《Histochemistry and cell biology》2004,122(3):191-200
An important subgroup of adhesion molecules is the superfamily of cadherins, which takes part in cell recognition and differentiation during development. To our knowledge only one study describing N-cadherin expression in developing human brain has been performed so far. Our aim is to identify N-cadherin expression to establish a relationship between its expression and function in human cerebral cortex during prenatal development. In the present study, localization and intensity of N-cadherin was investigated in developing cerebral cortex. Fetuses from spontaneous abortions (n=13) were obtained from first, second, and third trimesters. Western blot analysis revealed three bands and the third trimester samples showed the strongest bands for N-cadherin. Cell processes, axon bundles, and some of the developing neurons revealed immunoreactivity for N-cadherin throughout pregnancy. The immunoreactivity increased in the developing neocortex and expanded from the ventricular layer toward the marginal zone as development progressed. Moreover, the immunoreactivity was strong in vascular endothelium during all three trimesters. We conclude that N-cadherin is dynamically related to the organization of cerebral cortex layers during prenatal development. The dynamic expression pattern implicates N-cadherin as a potential regulator of cell migration, axon extension and fasciculation, the establishment of synaptic contacts, and neurovascular angiogenesis in the developing human cerebral cortex. 相似文献
17.
18.
Identification and simian immunodeficiency virus infection of CD1d-restricted macaque natural killer T cells 下载免费PDF全文
Motsinger A Azimzadeh A Stanic AK Johnson RP Van Kaer L Joyce S Unutmaz D 《Journal of virology》2003,77(14):8153-8158
Natural killer T (NKT) cells express a highly conserved T-cell receptor (TCR) and recognize glycolipids in the context of CD1d molecules. We recently demonstrated that CD4+ NKT cells are highly susceptible to human immunodeficiency virus type 1 (HIV-1) infection and are selectively depleted in HIV-infected individuals. Here, we identified macaque NKT cells using CD1d tetramers and human Valpha24 antibodies. Similar to human NKT cells, alpha-galactosylceramide (alpha-GalCer)-pulsed dendritic cells activate and expand macaque NKT cells. Upon restimulation with alpha-GalCer-pulsed CD1d(+) cells, macaque NKT cells secreted high levels of cytokines, a characteristic of these T cells. Remarkably, the majority of resting and activated macaque NKT cells expressed CD8, and a smaller portion expressed CD4. Macaque NKT cells also expressed the HIV-1/simian immunodeficiency virus (SIV) coreceptor CCR5, and the CD4+ subset was susceptible to SIV infection. Identification of macaque NKT cells has major implications for delineating the role of these cells in nonhuman primate disease models of HIV as well as other pathological conditions, such as allograft rejection and autoimmunity. 相似文献
19.
Uppal RS Khan U Kakar S Talas G Chapman P McGrouther AD 《Plastic and reconstructive surgery》2001,108(5):1218-1224
The possibility of altering the pathophysiology of keloid scars was investigated in 11 patients, using a single application of 5-fluorouracil solution for 5 minutes after extralesional excision was performed. Similar excisional wounds treated with phosphate-buffered saline for 5 minutes served as synchronous controls. An objective scoring system and subjective assessment were made to assay the change in the quality of the wound-healing and scar tissue produced by this treatment. A keloid scar score was used at regular time intervals after treatment to assess the quality of scar produced, thereby enabling the treated and control scars to be clinically compared.Biopsies were taken of the control and treated scars 1 month after treatment; the biopsy specimens were then subjected to immunohistochemical analysis as well as a functional assessment of cultured keloid fibroblasts. The immunohistochemical antigens assayed were Ki-67 (also called MIB-1; a marker of cell proliferation); vascular cell adhesion molecule-1 (a marker of inflammation); transforming growth factor beta-1 (a factor involved in scarring) and CD-68 (a macrophage-specific marker). Fibroblast-populated collagen lattices provided a functional assessment of fibroblast contraction.All treated and control wounds healed without any dehiscence or infection. The keloid scar score revealed that there was a perceived improvement in condition for those treated with 5-fluorouracil, compared with the control specimens, during the 6-month follow-up period in the five patients who attended all their clinic appointments; data on later recurrence are not complete as yet. The wounds treated with 5-fluorouracil produced scars that had a significant (p < 0.01) reduction in all the markers assayed, apart from CD-68. Functionally, the keloid fibroblasts from three of five of the treated patients showed reduced contractile capacity.This pilot study demonstrates that a "single-touch" technique with 5-fluorouracil can produce a change in the characteristics of the healing keloid wound after extralesional excision. Long-term studies are required to elucidate the correct dosage and time of exposure to improve the efficacy of this potential treatment. 相似文献
20.
Nef-mediated downregulation of CD4 enhances human immunodeficiency virus type 1 replication in primary T lymphocytes 下载免费PDF全文
The accessory protein Nef plays a crucial role in primate lentivirus pathogenesis. Nef enhances human immunodeficiency virus type 1 (HIV-1) infectivity in culture and stimulates viral replication in primary T cells. In this study, we investigated the relationship between HIV-1 replication efficiency in CD4(+) T cells purified from human blood and two various known activities of Nef, CD4 downregulation and single-cycle infectivity enhancement. Using a battery of reporter viruses containing point mutations in nef, we observed a strong genetic correlation between CD4 downregulation by Nef during acute HIV-1 infection of activated T cells and HIV-1 replication efficiency in T cells. In contrast, HIV-1 replication ability was not significantly correlated with the ability of Nef to enhance single-cycle virion infectivity, as determined by using viruses produced in cells lacking CD4. These results demonstrate that CD4 downregulation by Nef plays a crucial role in HIV-1 replication in activated T cells and underscore the potential for the development of therapies targeting this conserved activity of Nef. 相似文献