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Phosphate-solubilizing bacteria (PSB) increase phosphate bioavailability, thereby reducing the application frequency of chemical fertilizers in the production of Nicotiana tabacum (tobacco). In this study, PSB were isolated from tobacco plants for the first time. These PSB were screened in vitro for their ability to solubilize inorganic P (Pi) when grown in association with tobacco plants. Thirty-six PSB with the ability to solubilize Pi were isolated and screened for their indolyl-3-acetic acid and siderophore-producing capabilities. In addition, all 36 PSB strains had a partial fragment of their 16S rRNA gene sequenced. The analysis revealed high sequence identity to 16S rDNA sequences from Bacillus, Arthrobacter, Providencia, Enterobacter, Proteus, Psychrobacter, Serratia, Rhodococcus, Pseudomonas, Ochrobactrum, and Acinetobacter. Of the 36 PSB strains analyzed, three (Psychrobacter alimentarius HB15, Enterobacter ludwigii HB21, and Ochrobactrum haematophilum HB36) were selected for a controlled plant inoculation experiment. Inoculation of tobacco plants with these bacterial strains significantly increased plant dry weight. Additionally, inoculation increased P, K, and N uptake by tobacco seedlings as well as soil P availability. The increases observed with inoculation were even more pronounced when tricalcium phosphate (TCP) was added to the soil. The phosphate-solubilizing activity of these three strains was correlated with the release of gluconic, tartaric, acetic, and citric organic acids. Overall, co-inoculation of PSB and TCP appears to represent a promising option for increasing the yield of tobacco plants. The adoption of this technique could provide a pathway to reducing fertilizer input in agricultural settings.
Human PCAN1 (prostate cancer gene 1) is a prostate-specific gene that is highly expressed in prostate epithelial tissue, and frequently mutated in prostate tumors. To better understand the regulation of the PCAN1 gene, a 2.6-kb fragment of its 5′ flanking region was obtained by PCR. Its promoter activity was examined via the dual-luciferase reporter assay after it had been cloned into a pGL3-basic vector generating pGL3-p2.6kb and transfected into LNCaP cells. pGL3-basic and pGL3-control were respectively used as the negative and positive controls. Sequence analysis with the MatInspector database showed that some possible binding sites for the transcriptional factors, NKX3.1, P53, SP1, cEBP and the PPAR/RXR heterodimers may locate on a 2.6-kb region upstream of the PCAN1 gene. To examine the relevant regulation of PCAN1, pGL3-p2.6kb was transfected into the prostate cancer cell line LNCaP, which was treated with R1881 (10−7∼10−9 mol/l), 17β-estradiol (17β-E2, 10−7∼10−9 mol/l), all-trans-retinoic acid (all-trans-RA, 10−5∼10−7 mol/l) or 9-cis-retinoic acid (9-cis-RA, 10−5∼10−7 mol/l), and eukaryotic expression plasmids of NKX3.1, p53, Sp1, Pten, PPARγ or cEBPα were cotransfected with pGL3-p2.6kb into LNCaP cells. pRL-TK, a Renilla luciferase reporter vector, was cotransfected into all the transfection lines as an internal control. The activities of pGL3-p2.6kb (PCAN1 promoter) were analyzed via the dual-luciferase reporter assay 48 h after transfection. The results showed that 9-cis-RA enhanced the PCAN1 promoter activity in a dose-dependent manner, while R1881, 17β-E2 and all-trans-RA had no significant effect on PCAN1 promoter activities. Cotransfection with pGL3-p2.6kb and the expression plasmids of NKX3.1, p53, Sp1 or Pten respectively resulted in 1.66-, 2.48-, 2.00-and 1.72-fold 2.6 kb PCAN1 promoter activity increases relative to the controls, which were cotransfected with pcDNA3.1(+), while cotransfection of PPARγ and cEBPα yielded no significant effect on PCAN1 promoter activities. These results could be applied for further study of the function and transcription regulation of the PCAN1 gene in prostate development and carcinogenesis.
Ecological security is the comprehensive characterization of the noosystem’s overall collaborative capacity in relation to human welfare within a whole society. Recent years, however, have witnessed the excessive exploitation of natural resources via anthropogenic activities that have consistently triggered or accelerated ecological deterioration. In addition, an adequate ecological security assessment has yet to be conducted in a steppe ecoregion, especially when considering that the steppe is the major ecoregion category in China. In this study, we selected a typical steppe ecoregion in Inner Mongolia, northern China, as a representative region to conduct a spatiotemporal assessment of ecological security from both global and local perspectives. Along with an evaluation indicator system constituting 25 separate indicators covering three different systems (society, economy, and nature), we applied an improved grey target decision-making method in the initial indicator conversion process. As it pertains to weight determination, we employed a weight calculation method that weighed all indicators synthetically. Research findings indicated that a progressive deterioration of ecological security has been observed in the typical steppe ecoregion of China from 1990 to 2014, with a decline in the security situation and even more severe deterioration observed from a local perspective than a global perspective. Social and economic systems, specifically an excessive rural population and unreasonable development (mainly grazing and mining), were the major factors that promoted ecological security deterioration, while the natural system has contributed only slightly to this deterioration.
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