Minimal Wave Speed of Bacterial Colony Model with Saturated Functional Response

By considering bacterium death and general functional response we develop previous model of bacterial colony which focused on the traveling speed of bacteria. The minimal wave speed for our model is expressed by parameters and the necessary and sufficient conditions for traveling wave solutions (TWSs) are given. To prove the existence of TWSs, an auxiliary system is introduced and the existence of TWSs for this auxiliary system is proved by Schauder’s fixed point theorem. The limit arguments show the existence of TWSs for original system. By introducing negative one-sided Laplace transform, we prove the nonexistence of TWSs

ShRNA-mediated gene silencing of MTA1 influenced on protein expression of ER alpha, MMP-9, CyclinD1 and invasiveness, proliferation in breast cancer cell lines MDA-MB-231 and MCF-7 in vitro

<p>Abstract</p> <p>Background</p> <p>MTA1(metastasis associated-1) is a tumor metastasis associated candidate gene and overexpression in many human tumors, including breast cancer. In this study, we investigated depressive effect on MTA1 by MTA1-specific short hairpin RNA(shRNA) expression plasmids in human breast cancer cell lines MDA-MB-231 and MCF-7, and effect on protein levels of ER alpha, MMP-9, cyclinD1, and tumor cell invasion, proliferation.</p> <p>Methods</p> <p>ShRNA expression vectors targeting MTA1 was constructed and transfected into human breast cancer cell lines MDA-MB-231 and MCF-7. The transfection efficiency was evaluated by fluorescence microscopy, mRNA levels of MTA1 were detected by reverse transcription-polymerase chain reaction (RT-PCR), protein levels of ER alpha, MMP-9 and cyclinD1 were detected by Western blotting, respectively. Tumor cells invasive ability were evaluated by Boyden chamber assay, the cells proliferation were evaluated using cell growth curve and MTT analysis, the cell cycle analysis was performed using flow cytometry.</p> <p>Results</p> <p>Down-regulation of MTA1 by RNAi approach led to re-expression of ER alpha in ER-negative breast cancer cell lines MDA-MB-231, and reduced protein levels of MMP-9 and CyclinD1, as well as decreased tumor cell invasion and proliferation, more cells were blocked in G0/G1 stage(P < 0.05). However, after inhibiting mRNA levels of MTA1, protein expression of ER alpha, MMP-9, cyclinD1 and the changes of cancer cells invasiveness, proliferation, cells cycle were no statistical difference in ER-positive human breast cancer cell lines MCF-7 (P > 0.05).</p> <p>Conclusions</p> <p>ShRNA targeted against MTA1 could specifically mediate the MTA1 gene silencing and consequentially recover the protein expression of ER alpha, resulting in increase sensitivity of antiestrogens, as well as suppress the protein levels of MMP-9 and cyclinD1 in ER-negative human breast cancer cell lines MDA-MB-231. Silencing effect of MTA1 could efficiently inhibit the invasion and proliferation in MDA-MB-231 cells. The shRNA interference targeted against MTA1 may have potential therapeutic utility in human breast cancer.</p

Probiotic Strain \u3cem\u3eStenotrophomonas acidaminiphila\u3c/em\u3e BJ1 Degrades and Reduces Chlorothalonil Toxicity to Soil Enzymes, Microbial Communities and Plant Roots

Chlorothalonil, a non-systemic and broad-spectrum fungicide, is widely used to control the pathogens of agricultural plants. Although microbial degradation of chlorothalonil is known, we know little about the colonization and degradation capacity of these microbes in the natural and semi-natural soil environments. Therefore, we studied the colonization and detoxification potential of a chlorothalonil degrading Stenotrophomonas acidaminiphila probiotic strain BJ1 in the soil under green conditions. The results from polymerase chain reaction-denaturing gradient gel electrophoresis demonstrated that probiotic strain BJ1 successfully colonized the soil by competing with the native biota. Moreover, the bacterial inoculation stimulated some members of indigenous soil microbial communities. Meantime, the degradation half-life of chlorothalonil decreased from 9.0 to 4.9 days in the soil environment. Moreover, the results from enzymatic activities and micronucleus test of Vicia faba root tips showed that the probiotic strain BJ1 reduced the ecotoxicity and genotoxicity of chlorothalonil in the soil. We suggest that probiotic strains like BJ1 could potentially alleviate the toxic effects of pesticides on soil microbes and plant roots under greenhouse conditions

Chemical Vapor Deposition to Titanium Dioxide Thin Films.

TiO\sb2 thin films have been prepared by the thermal decomposition of titanium tetra-isopropoxide (TTIP) in two low pressure chemical vapor deposition (LPCVD) reactors. The two reactors are the vertical tube hot-wall reactor and the stagnation point flow single-wafer cold-wall reactor. The effects of TTIP partial pressure, substrate temperature, gas flow rate, and reactor pressure on the growth rate of TiO\sb2 film were examined. Aerosol formation, wall effects, the effect of water content, and the effect of reactor geometry were also investigated. The experiments were performed in the substrate temperature range 225-400\sp\circC, inlet TTIP partial pressure range 6.4\times10\sp{-4} $-$ 0.4 torr, reactor pressure range 1.5-8 torr, and gas flow rate range 12-192 sccm. Growth rates up to 5 $\mu$m/h were obtained. The TiO\sb2 films were characterized by X-ray diffraction and scanning electron microscopy. Only anatase TiO\sb2 films were obtained under the present experimental conditions. The morphology of TiO\sb2 films varies with the reactor used. A two-dimensional model for reactor transport and kinetic mechanism has been developed. A homogeneous gas phase reaction mechanism was utilized in the model. Aerosol formation in the gas phase was considered. To save computation time, simplified flow models were used in the modeling. The model equations were solved using a control volume based finite difference method. The model predictions of growth rates and uniformity of TiO\sb2 films agree well with the experimental results. Addition of multi-component diffusion coefficients and thermal diffusion in the model are recommended to improve the model predictions