ABSTRACT
Atmospheric haze pollution is a popular environmental issue in recent years. The aerosols reduce solar radiation reaching land surface, with consequences on the growth of crops. In order to examine the effects of low solar radiation intensity on the physiological characteristics and mineral nutrition of grain crops, the random designed field experiment of rice cultivar 'Nanjing 5055' planted under different shading degrees (CK, natural sunlight control; Y1 and Y2 were treatments with shading rates of 19% and 45%, respectively) were conducted. The response of chlorophyll content (SPAD), leaf area index (LAI), net photosynthetic rate of leaves, grain yields and secondary/micro element contents (Ca, Mg, Fe, Zn, Mn, Cu) in rice were measured during key growth stages (jointing, heading, and grain filling stages). Results showed that, shading treatments inhibited the synthesis of photosynthetic products and reduced the LAI during the whole growing period, but at the early stage it did not affect the chlorophyll content, which was significantly increased at the late growth stage. Compared with CK, the 1000-grain weight of rice was decreased by 14.4% and 18.4%, and seed setting rate was decreased by 4.3% and 12.9%, which resulted in rice yield reduction. With the increases of shading rates, rice yield was decreased by 58.5% and 66.4%, respectively. The nutrient concentrations, especially for the micro-elements, in brown rice and glume were increased. Shading had a negative effect on rice growth, which would eventually reduce the crop production. The higher contents of heavy metals such as Cu and Mn would be a pollution risk for human health. Therefore, the impacts of weakened solar radiation on quantity and quality of crops need comprehensive evaluation.
Subject(s)
Oryza , Chlorophyll , Edible Grain , Humans , Photosynthesis , Plant LeavesABSTRACT
OBJECTIVE: To investigate the possibility of using generation 5 polyamidoamine dendrimers (G5-PAMAM-D) as gene vector for eukaryotic expression plasmid of siRNA in prostate carcinoma in vitro and vivo. METHODS: Firstly, eukaryotic expression vector of siRNA pSilencing 4.1-EGFP-shRNA, specific for enhanced green fluorescent protein (EGFP), pSilencing 4.1-STAT3-shRNA for signal transducers and activators of transcription 3 (STAT3) was constructed. pEGFP-C1 and pSilencing 4.1-EGFP-shRNA were cotransfected into prostate cancer cells PC-3 and 22Rv1 with G5-PAPAM-D as vector, and to observe silencing of EGFP. Next, pSilencing 4.1-STAT3-shRNA was transfected into PC-3 and 22Rv1 cells by G5-PAPAM-D, Western blotting and apoptosis staining was used to detect silencing of STAT3 and growth inhibition. Thirdly, BALB/C mice subcutaneous tumor model was made with PC-3 cells. Polyplex of G5-PAMAM-D and pSilencing 4.1-STAT3-shRNA was injected intratumorally. The tumor volume was measured and recorded. RESULTS: Fluorescence detection and Western blotting analysis demonstrated that G5-PAMAM-D was able to deliver Silencing 4.1-EGFP-shRNA and pSilencing 4.1-STAT3-shRNA into the two prostate cancer cell lines, and shRNA was expressed to induce silence of EGFP and STAT3. MTT results showed that proliferation of prostate cancer cells was suppressed by G5-PAMAM-D/pSilencing 4.1-STAT3-shRNA and induced apoptosis of PC-3 cells in vitro. Human prostate cancer in mice was successfully formed by inoculation of PC-3 cells into male BABL/C mice. In G5-PAMAM-D/pSilencing 4.1-STAT3-shRNA treated group, the tumor volume was shrank remarkably at 9 days after treatment and tumor growth was retarded compared with control groups. CONCLUSION: GS-PAMAM-D nanoparticles can be used to deliver plasmid vector expressing shRNA into prostate cancer cells effectively in vitro and vivo. It appears to be a promising gene vector for RNA interference therapy in prostate cancer.
