Magnesium (Mg(2+)) is an essential macronutrient for plant growth and development, and the CorA/MRS2/MGT-type Mg(2+) transporters play important roles in maintaining Mg(2+) homeostasis in plants. Although the MRS2/MGT genes have been identified in two model plant species, Arabidopsis and rice, a comprehensive analysis of the MRS2/MGT gene family in other plants is lacking. In this work, 12 putative MRS2/MGT genes (ZmMGT1- ZmMGT12) were identified in maize and all of them were classified into five distinct subfamilies by phylogenetic analysis. A complementation assay in the Salmonella typhimurium MM281 strain showed that five representatives of the 12 members possess Mg(2+) transport abilities. Inhibition of ZmMGT protein activity using the hexaamminecobalt (III) (Co-Hex) inhibitor indicated that the ZmMGT protein mediated both low-affinity and high-affinity Mg(2+) transport in maize. A semi-quantitative reverse transcription-PCR (RT-PCR) analysis revealed that eight genes were constitutively expressed in all of the detected tissues, with one being specifically expressed in roots and three having no detectable expression signals. A quantitative RT-PCR analysis showed that some ZmMGT members displayed differential responses to Mg(2+) deficiency and aluminum (Al) stress. Furthermore, root growth inhibition and Mg(2+) accumulation analyses in two maize inbred lines, which conferred different levels of Al tolerance, revealed that ZmMGT proteins contributed to the Al resistance of the Al tolerance genotype. We hypothesize that ZmMGT family members function as Mg(2+) transporters and may play a role in linking Mg(2+) deficiency and Al stress responses. Our results will be valuable in a further analysis of the important biological functions of ZmMGT members in maize.
Aim: Proteins with legume lectin domains are known to possess a wide range of biological functions. Here, the antitumor effects of two representative legume lectins, concanavalin A (ConA) and Sophora flavescens lectin (SFL), on human breast carcinoma cells were investigated in vitro and in vivo. Methods: Human breast carcinoma MCF-7 cells and human normal mammary epithelial MCF-10A cells were examined. Cell viability was detected using WST-1 and CCK-8 assays. Cell apoptosis was analyzed with Hoechst 33258 staining. Cell cycle was investigated using flow cytometry. The expression of relevant proteins was measured using Western blotting. Breast carcinoma MCF-7 bearing nude mice were used to study the antitumor effects in vivo. The mice were injected with ConA (40 mg/kg, ip) and SFL (55 mg/kg, ip) daily for 14 d. Results: ConA and SFL inhibited the growth of MCF-7 cells in dose-and time-dependent manners (IC 50 values were 15 and 20 μg/mL, respectively). Both ConA and SFL induced apoptotic morphology in MCF-7 cells without affecting MCF-10A cells. ConA and SFL dosedependently increased the sub-G 1 proportion in MCF-7 cells, while SFL also triggered the G 2 /M phase cell cycle arrest. Both ConA and SFL dose-dependently increased the activities of caspase-3 and caspase-9 and release of cytochrome c from mitochondria into cytoplasm, up-regulated Bax and Bid, and down-regulated Bcl-2 and Bcl-X L in MCF-7 cells. ConA reduced NF-κB, ERK, and JNK levels, and increased p53 and p21 levels, while SFL caused similar changes in NF-κB, ERK, p53, and p21 levels, but did not affect JNK expression. Administration of ConA and SFL significantly decreased the subcutaneous tumor mass volume and weight in MCF-7 bearing nude mice. Conclusion: ConA and SFL exert anti-tumor actions against human breast carcinoma MCF-7 cells both in vitro and in vivo.
Common buckwheat is a health-care crop, and continuous cropping is one of the main factors restricting its high-yielding. In order to clarify the mechanism of continuous cropping of buckwheat, 4, 5and 6 years continuous cropping treatments were set up. We obtained the following results. The available nutrients content in rhizosphere soil, soil enzyme activity, leaf area, chlorophyll and soluble protein content, the peroxidase(POD) activity of leaves, agronomic traits, root index (except average diameter) of Fengtian1(FT1) decreased significantly with the increase of continuous cropping years. While, soil pH and the number of fungi in rhizosphere soil increased significantly, the number of bacteria in rhizosphere soil and the activity of catalase (CAT) and superoxide dismutase(SOD) in leaves first increased and then decreased. The yields of continuous cropping for 6 years were 12 times lower than the control crop. In conclusion, continuous cropping has certain effects on growth and yields of buckwheat.
Antibiotics have been described to modulate bacterial virulence gene expression. This study aimed to assess the changes caused by anti-Staphylococcus agents in the transcription of leucocidin ED (lukED) gene of Staphylococcus aureus strain Newman in vitro and in vivo and to determine whether the altered expression is agr dependent. The bacteria were exposed to subinhibitory concentrations [1/2, 1/4, or 1/8 minimal inhibitory concentration (MIC)] of 11 antibiotics, and the expression of lukE and agr-effector RNAIII was determined using qRT-PCR. In vivo experiments were performed to evaluate the impact exerted by six representative antibiotics on the transcription of both genes. Molecular analysis showed that in vitro lukE transcription was dramatically promoted in the Newman strain exposed to sub-MICs of vancomycin, trimethoprim-sulfamethoxazole, clindamycin, gentamicin, daptomycin, and ciprofloxacin and considerably reduced when stimulated by cefazolin, erythromycin, rifampicin, tigecycline, and linezolid. In the murine abscess model, tigecycline significantly decreased the transcription of lukE and the bacterial numbers, whereas vancomycin increased them; although cefazolin increased the lukE expression (contrary to the in vitro effect), it had a remarkable role in reducing bacterial load. The correspondence analysis shows that RNAIII expression varied under seven of 11 antibiotics in vitro, and six drugs in vivo were consistent with lukE transcripts. In conclusion, our data show that anti-Staphylococcus antibiotics exert modulatory effects on lukE expression in vitro and/or in vivo, and the changed expression caused by some drugs may be involved with agr activity, thus providing a guide to choose appropriate agents to avoid promoting bacterial virulence in lukED-positive S. aureus infections.
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