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111.
112.
Hexavalent chromium is one of the most widely distributed environmental contaminants. Given the carcinogenic and mutagenic
consequences of Cr(VI) exposure, the release of Cr(VI) into the environment has long been a major concern. While many reports
of microbial Cr(VI) reduction are in circulation, very few have demonstrated Cr(VI) reduction under alkaline conditions. Since
Cr(VI) exhibits higher mobility in alkaline soils relative to pH neutral soils, and since Cr contamination of alkaline soils
is associated with a number of industrial activities, microbial Cr(VI) reduction under alkaline conditions requires attention.
Soda lakes are the most stable alkaline environments on earth, and contain a wide diversity of alkaliphilic organisms. In
this study, a bacterial isolate belonging to the Halomonas genus was obtained from Soap Lake, a chemically stratified alkaline lake located in central Washington State. The ability
of this isolate to reduce Cr(VI) and Fe(III) was assessed under alkaline (pH = 9), anoxic, non-growth conditions with acetate
as an electron donor. Metal reduction rates were quantified using Monod kinetics. In addition, Cr(VI) reduction experiments
were carried out in the presence of Fe(III) to evaluate the possible enhancement of Cr(VI) reduction rates through electron
shuttling mechanisms. While Fe(III) reduction rates were slow compared to previously reported rates, Cr(VI) reduction rates
fell within range of previously reported rates. 相似文献
113.
The liver is the main organ that clears circulating lipopolysaccharide (LPS), and hepatocytes are a major cell type involved in LPS uptake. Little is known about the mechanisms for LPS internalization in hepatocytes and what signaling pathways are involved. We show here that LPS uptake is initiated after formation of a multi-receptor complex within lipid rafts. We find that essential components for LPS uptake are CD14, TLR4, MD2, and the beta2-integrin CD11b/CD18. Activation of p38 MAPK is also essential for the initiation of LPS uptake, and interestingly, we show that this activation is not through TLR4 signaling by MyD88 but through activation of TIRAP via CD11b/CD18. However, TLR4/MD2 remain essential components at the cell surface as part of the LPS receptor complex. We therefore suggest novel roles for TLR4/MD2, CD11b/CD18, TIRAP, and p38 MAPK in LPS uptake by hepatocytes. 相似文献
114.
The effects of the Fanconi anemia zinc finger (FAZF) on cell cycle, apoptosis, and proliferation are differentiation stage-specific 总被引:5,自引:0,他引:5
Dai MS Chevallier N Stone S Heinrich MC McConnell M Reuter T Broxmeyer HE Licht JD Lu L Hoatlin ME 《The Journal of biological chemistry》2002,277(29):26327-26334
115.
Thomas Jans Erika Graf Christian Jacob Ulrike Zwanzger Silke Groß-Lesch Swantje Matthies Evgeniy Perlov Klaus Hennighausen Melanie Jung Michael Rösler Monika Schulte-Altedorneburg Alexander von Gontard Susann Hänig Esther Sobanski Barbara Alm Luise Poustka Lucia Bliznak Michael Colla Laura Gentschow Roland Burghardt Harriet Salbach-Andrae Katja Becker Martin Holtmann Christine Freitag Andreas Warnke Alexandra Philipsen 《Attention deficit and hyperactivity disorders》2013,5(1):29-40
116.
Ectomycorrhizal fungal (EMF) communities vary among microhabitats, supporting a dominant role for deterministic processes in EMF community assemblage. EMF communities also differ between forest and clearcut environments, responding to this disturbance in a directional manner over time by returning to the species composition of the original forest. Accordingly, we examined EMF community composition on roots of spruce seedlings planted in three different microhabitats in forest and clearcut plots: decayed wood, mineral soil adjacent to downed wood, or control mineral soil, to determine the effect of retained downed wood on EMF communities over the medium and long term. If downed and decayed wood provide refuge habitat distinct from that of mineral soil, we would expect EMF communities on seedlings in woody habitats in clearcuts to be similar to those on seedlings planted in the adjacent forest. As expected, we found EMF species richness to be higher in forests than clearcuts (P ≤ 0.01), even though soil nutrient status did not differ greatly between the two plot types (P ≥ 0.05). Communities on forest seedlings were dominated by Tylospora spp., whereas those in clearcuts were dominated by Amphinema byssoides and Thelephora terrestris. Surprisingly, while substrate conditions varied among microsites (P ≤ 0.03), especially between decayed wood and mineral soil, EMF communities were not distinctly different among microhabitats. Our data suggest that niche partitioning by substrate does not occur among EMF species on very young seedlings in high elevation spruce-fir forests. Further, dispersal limitations shape EMF community assembly in clearcuts in these forests. 相似文献
117.
118.
ATP synthases - rotary nano machines - consist of two major parts, F(O) and F(1), connected by two stalks: the central and the peripheral stalk. In spinach chloroplasts, the central stalk (subunits gamma, epsilon) forms with the cylinder of subunits III the rotor and transmits proton motive force from F(O) to F(1), inducing conformational changes of the catalytic centers in F(1). The epsilon subunit is an important regulator affecting adjacent subunits as well as the activity of the whole protein complex. Using a combination of chemical cross-linking and mass spectrometry, we monitored interactions of subunit epsilon in spinach chloroplast ATP synthase with III and gamma. Onto identification of interacting residues in subunits epsilon and III, one cross-link defined the distance between epsilon-Cys6 and III-Lys48 to be 9.4 A at minimum. epsilon-Cys6 was competitively cross-linked with subunit gamma. Altered cross-linking yields revealed the impact of nucleotides and Mg(2+) on cross-linking of subunit epsilon. The presence of nucleotides apparently induced a displacement of the N-terminus of subunit epsilon, which separated epsilon-Cys6 from both, III-Lys48 and subunit gamma, and thus decreasing the yield of the cross-linked subunits epsilon and gamma as well as epsilon and III. However, increasing concentrations of the cofactor Mg(2+) favoured cross-linking of epsilon-Cys6 with subunit gamma instead of III-Lys48 indicating an approximation of subunits gamma and epsilon and a separation from III-Lys48. 相似文献
119.
Hall JV Schell M Dessus-Babus S Moore CG Whittimore JD Sal M Dill BD Wyrick PB 《Cellular microbiology》2011,13(8):1183-1199
The oestrogen receptor (ER) α-β+ HEC-1B and the ERα+β+ Ishikawa (IK) cell lines were investigated to dissect the effects of oestrogen exposure on several parameters of Chlamydia trachomatis infection. Antibody blockage of ERα or ERβ alone or simultaneously significantly decreased C. trachomatis infectivity (45-68%). Addition of the ERβ antagonist, tamoxifen, to IK or HEC-1B prior to or after chlamydial infection caused a 30-90% decrease in infectivity, the latter due to disrupted eukaryotic organelles. In vivo, endometrial glandular epithelial cells are stimulated by hormonally influenced stromal signals. Accordingly, chlamydial infectivity was significantly increased by 27% and 21% in IK and HEC-1B cells co-cultured with SHT-290 stromal cells exposed to oestrogen. Endometrial stromal cell/epithelial cell co-culture revealed indirect effects of oestrogen on phosphorylation of extracellular signal-regulated kinase and calcium-dependant phospholipase A2 and significantly increased production of interleukin (IL)-8 and IL-6 in both uninfected and chlamydiae-infected epithelial cells. These results indicate that oestrogen and its receptors play multiple roles in chlamydial infection: (i) membrane oestrogen receptors (mERs) aid in chlamydial entry into host cells, and (ii) mER signalling may contribute to inclusion development during infection. Additionally, enhancement of chlamydial infection is affected by hormonally influenced stromal signals in conjunction with direct oestrogen stimulation of the human epithelia. 相似文献
120.
Epiphyses of the proximal tibiae of 7-week-old normal and homozygous recessive brachymorphic mice (bm/bm) were immunostained
using a monoclonal antibody to basic fibroblast growth factor to determine its expression in growth plate cartilage, osteoblasts
on the surfaces of the primary spongiosa and articular cartilage. In the normal growth plate, the immunoreactive factor was
present in chondrocytes of the proliferating and upper hypertrophic zones but absent from lower hypertrophic chondrocytes.
Immunostaining was present only in the territorial extracellular matrix immediately adjacent to the chondrocytes of the proliferating
and upper hypertrophic zones. Osteoblasts of the primary spongiosa stained heavily in normal mice. Strong staining was observed
in intermediate zone articular chondrocytes. Cells in the superficial layer of articular cartilage were unstained. The extracellular
matrix of the articular cartilage was completely free of immunostaining. In contrast, the reduced size of bm/bm growth plates
was accompanied by significantly reduced staining intensity in proliferating and upper hypertrophic chondrocytes, and staining
was absent from the territorial extracellular matrix of all zones of the bm/bm growth plate. Osteoblasts of the primary spongiosa
of bm/bm mice stained less than those of normal mice. Articular cartilage chondrocytes in the intermediate zone stained with
less intensity in bm/bm mice, and the cells of the superficial layer were unstained. The extracellular matrix of bm/bm articular
cartilage was completely free of staining. Brachymorphic epiphyseal growth plate and articular chondrocytes, and osteoblasts
in the primary spongiosa, express reduced amounts of immunoreactive fibroblast growth factor-2. This phenotypical characteristic
may be associated with abnormal endochondral ossification and development of bone in brachymorphic mice 相似文献