[Effect of LINE1-ORF1p overexpression on the proliferation of nephroblastoma WT_CLS1 cells].

OBJECTIVE: To prepare the LINE1-ORF1p polyclonal antibody, and to study the effect of LINE1-ORF1p on the proliferation of nephroblastoma WT_CLS1 cells. METHODS: A genetic engineering method was used to achieve prokaryotic expression of LINE1-ORF1p, and rabbits were immunized with LINE1-ORF1p to prepare polyclonal antibody. Indirect ELISA was used to evaluate antibody titer, and Western blot and immunohistochemistry were used to evaluate the specific ability of antibody to recognize LINE1-ORF1p. The eukaryotic expression vector pEGFP-N1-LINE1-ORF1 was constructed and used to transfect WT_CLS1 cells. Western blot and qRT-PCR were used to measure the protein and mRNA expression of LINE1-ORF1, respectively, and cell proliferation assay and colony-forming assay were used to evaluate the effect of LINE1-ORF1p on the proliferation of WT_CLS1 cells and the formation of tumor cell clone. RESULTS: The LINE1-ORF1p antibody prepared had a titer of >1:16 000 and could specifically recognize LINE1-ORF1p in cells and tumor tissue. WT_CLS1 cells transfected with pEGFP-N1-LINE1-ORF1 had significant increases in the mRNA and protein expression of LINE1-ORF1 and significantly enhanced cell proliferation ability and colony formation ability (P<0.05). CONCLUSIONS: LINE1-ORF1p can promote the growth of nephroblastoma cells and the formation of tumor cell clone, and may be involved in the pathogenesis of nephroblastoma.

Site-directed mutagenesis identified the key active site residues of alcohol acyltransferase PpAAT1 responsible for aroma biosynthesis in peach fruits.

The aroma of peach fruit is predominantly determined by the accumulation of γ-decalactone and ester compounds. A previous study showed that the biosynthesis of these aroma compounds in peach fruit is catalyzed by PpAAT1, an alcohol acyltransferase. In this work, we investigated the key active site residues responsible for γ-decalactone and ester biosynthesis. A total of 14 candidate amino acid residues possibly involved in internal esterification and 9 candidate amino acid residues possibly involved in esterification of PpAAT1 were assessed via site-directed mutagenesis. Analyses of the in vitro enzyme activities of PpAAT1 and its site-directed mutant proteins (PpAAT1-SMs) with different amino acid residue mutations as well as the contents of γ-decalactone in transgenic tobacco leaves and peach fruits transiently expressing PpAAT1 and PpAAT1-SMs revealed that site-directed mutation of H165 in the conserved HxxxD motif led to lost enzymatic activity of PpAAT1 in both internal esterification and its reactions, whereas mutation of the key amino acid residue D376 led to the total loss of γ-decalactone biosynthesis activity of PpAAT1. Mutations of 9 and 7 other amino acid residues also dramatically affected the enzymatic activity of PpAAT1 in the internal esterification and esterification reactions, respectively. Our findings provide a biochemical foundation for the mechanical biosynthesis of γ-decalactone and ester compounds catalyzed by PpAAT1 in peach fruits, which could be used to guide the molecular breeding of new peach species with more favorable aromas for consumers.

[Effects of Varying Long-term Fertilization on Organic Carbon Mineralization and Priming Effect of Paddy Soil].

A laboratory incubation experiment was conducted using the 14C isotope labeling technique to study the characteristics of organic carbon mineralization and their response to glucose addition when treated with a combination of straw and chemical fertilizer (ST), inorganic fertilizer (NPK), and non-fertilization (CK). The cumulative mineralization rate (ratio of accumulated mineralization amount to total organic carbon content) in CK reaches 1.64% at the end of incubation (56 days). The cumulative mineralization rate during NPK and ST treatments is significantly lower than that in CK (by 0.34% and 0.39%, respectively). This indicates that long-term fertilization affects the soil carbon sequestration. Varying long-term fertilization influences the response of paddy soil to glucose addition and leads to different levels of the priming effect. The priming effect on soil organic carbon mineralization of the three treatments gradually changes from negative to positive with increasing incubation time. The significantly negative cumulative priming effect in ST and NPK after 56 d is 22.07 and 9.05 times higher than that in CK, respectively. The results of the structural equation model indicate that the NH4+-N and DOC contents indirectly influence the cumulative priming effect on soil organic carbon by affecting the MBC and MBN contents. The NH4+-N concentration has a direct and significant negative effect on the cumulative priming effect. In conclusion, long-term fertilization treatments reduce the cumulative organic carbon mineralization rate of paddy soil. Fertilizer, especially the combination of straw and chemical fertilizer, enhances the soil carbon sequestration and accumulation.

[Effect of CO2 Doubling and Different Plant Growth Stages on Rice Carbon, Nitrogen, and Phosphorus and Their Stoichiometric Ratios].

The variation characteristics of ecological stoichiometric ratios can reflect the nature of plant adaptation to environmental changes. The C, N, and P contetns, and their stoichiometric ratios in different organs of rice were studied using a CO2 continuous labeling system, by simulating the increase of atmospheric CO2 concentration (800×10-6). The results showed that CO2 doubling promoted the growth of rice organs and increased the root/shoot ratio. CO2 doubling reduced the shoot TN content in different growth periods, increased the C/N ratio in the rice root, shoot, and grain, decreased the N use efficiency, and improved the P use efficiency. Multiple comparison and Venn diagram analyses showed that CO2 concentration only has a significant impact on the TN content in the rice shoot; it contributed little to the variation in rice nutrient content and their stoichiometric ratios, indicating that CO2 doubling had no effect on these. Under the condition of elevated atmospheric CO2 concentrations, the C, N, and P contents and their stoichiometirc ratios, in rice organs had good homeostasis, and the stoichiometric change during growth periods was consistent with "the Growth Rate Theory". In farmland management, appropriate nitrogen fertilizers can alleviate the nutrient balance pressure caused by the increase in CO2 concentration.

[Responses of organic carbon mineralization and priming effect to phosphorus addition in paddy soils]. / ç¨»ç”°åœŸå£¤æœ‰æœºç¢³çŸ¿åŒ–åŠå ¶æ¿€å‘æ•ˆåº”å¯¹ç£·æ·»åŠ çš„å“åº”.

To understand the coupled controlling of carbon (C) and phosphorus (P) on the minera-lization of soil organic carbon and amended substrates in paddy soil, we investigated the effects of P addition on the decomposition of organic carbon and its induced priming effect by using 13C isotope probing technique in microcosm. The results showed that P addition accelerated the release of CO2 but inhibited the release of CH4, leading to 53.1% reduction of total accumulated CH4 and 70.5% reduction of the 13CH4 derived from exotic glucose-13C. P addition altered the carbon distribution during the microbial turnover progress, with 3.6% of glucose-13C being transferred into the labile carbon pool, therein significantly increased potential of the mineralization rate of exogenous C. A transient negative priming effect was observed in the early stage of incubation. With time prolonging, the priming effect on CO2 emission (PECO2) generally increased and then decreased after a peak. The priming effect on CH4 emission (PECH4) kept increasing and finally fluctuated at a relative stable value until the end of the experiment (100 days). P addition increased PECO2 by 32.3% but reduced PECH4 by 93.4%. Results from the RDA and Pearson analysis showed that electric conductivity, oxidation-reduction potential and dissolved organic carbon significantly affected soil C mineralization. There were significantly negative correlations between available phosphorus (Olsen-P) and 13CH4, and between Olsen-P and PECH4. In conclusion, with the addition of exogenous organic matter, P application could reduce CH4 emissions and inhibit its priming effect, acce-lerate the mineralization of SOC, probably improve the nutrient supply, and thus enhance the avai-lability of organic C and promote C cycling in paddy soil.

[Effects of Long-term Fertilization on Enzyme Activities in Profile of Paddy Soil Profiles].

The enzyme activity, which is closely related to soil material cycling (mineralization, transformation, etc.), can reflect soil quality and nutrient status. In order to explore the effect of long-term fertilization on the enzyme activity in paddy soil profile (0-40 cm), soils with organic fertilizer and inorganic fertilizer, and non-fertilized soils were selected, and the carbon and nitrogen contents, and the activities of ß-1,4-glucosidase (BG), and ß-1,4-N-acetylglucosaminidase (NAG) in 10cm depths of soil were analyzed. The results showed that the activities of BG and NAG in the soils treated with inorganic fertilizer and organic fertilizer increased by 0.73-47.87 nmol·(g·h)-1 and 1.33-128.81 nmol·(g·h)-1, and 0.19-9.72 nmol·(g·h)-1 and 0.92-57.66 nmol·(g·h)-1, respectively, compared to those for non-fertilized soil. Soil enzyme activity decreased with increasing soil depth. Soil enzyme activity in soil from 0-20 cm was significantly higher than that of soil from 20-40 cm. Soil enzyme activities were significantly affected by long term fertilization at different soil depths. RDA analysis showed that soil carbon and nitrogen contents had significant positive relationships with the activities of BG and NAG in the 0-20 cm soil profiles, however, negative relationships were observed in the 20-40 cm soil profiles. The long-term application of organic fertilizer significantly increased soil biomass and enzyme activity, both of which decreased with the increase in soil depth. Long-term fertilization could increase soil nutrient contents, microbial biomass, and extracellular enzyme activities, which has important theoretical significance for optimizing farmland fertilizer management and improving soil productivity.

Dose estimation for nuclear power plant 4 accident in Taiwan at Fukushima nuclear meltdown emission level.

An advanced Gaussian trajectory dispersion model is used to evaluate the evacuation zone due to a nuclear meltdown at the Nuclear Power Plant 4 (NPP4) in Taiwan, with the same emission level as that occurred at Fukushima nuclear meltdown (FNM) in 2011. Our study demonstrates that a FNM emission level would pollute 9% of the island's land area with annual effective dose ≥50 mSv using the meteorological data on 11 March 2011 in Taiwan. This high dose area is also called permanent evacuation zone (denoted as PEZ). The PEZ as well as the emergency-planning zone (EPZ) are found to be sensitive to meteorological conditions on the event. In a sunny day under the dominated NE wind conditions, the EPZ can be as far as 100 km with the first 7-day dose ≥20 mSv. Three hundred sixty-five daily events using the meteorological data from 11 March 2011 to 9 March 2012 are evaluated. It is found that the mean land area of Taiwan in becoming the PEZ is 11%. Especially, the probabilities of the northern counties/cities (Keelung, New Taipei, Taipei, Taoyuan, Hsinchu City, Hsinchu County and Ilan County) to be PEZs are high, ranging from 15% in Ilan County to 51% in Keelung City. Note that the total population of the above cities/counties is as high as 10 million people. Moreover, the western valleys of the Central Mountain Range are also found to be probable being PEZs, where all of the reservoirs in western Taiwan are located. For example, the probability can be as high as 3% in the far southern-most tip of Taiwan Island in Pingtung County. This shows that the entire populations in western Taiwan can be at risk due to the shortage of clean water sources under an event at FNM emission level, especially during the NE monsoon period.