Effect of Plant Type on Grain Yield of Maize Hybrid Grown in Diferent Densities

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MicroRNA-3666 regulates expression of phosphatase and tensin homologue deleted on chromosome ten in leukemic cells

AIM: To explore the regulatory effect of microRNA-3666 (miR-3666) on the expression of its target gene phosphatase and tensin homologue deleted on chromosome ten (PTEN) in leukemic cells. METHODS: miR-3666 expression levels in normal peripheral blood mononuclear cells and leukemic cells were determined by quantitative real-time PCR. miR-3666 targeting PTEN 3-untranslated region (3UTR) was predicted by TargetScan software. 3UTR of PTEN was inserted in the dual luciferase reporter vector psiCHECK2. The reporter activity was evaluated by the Dual-Luciferase Reporter Assay System after the luciferase promoter vector and miRNA were co-transfected into HEK293T cell line. K562 cells were transfected with synthetic miR-3666 inhibitor (anti-miR-3666) or a synthetic control miRNA (anti-miR-C). The expression of PTEN protein in the above transfected K562 cells was determined by Western blotting. RESULTS: miR-3666 was up-regulated in the human leukemic cell lines and primary leukemic cells compared to normal peripheral blood mononuclear cells. The results of dual luciferase assays validated PTEN as a specific target gene of miR-3666. Inhibition of miR-3666 resulted in an up-regulation of PTEN protein expression in the K562 cells. CONCLUSION: miR-3666 is over-expressed in leukemic cells. The abnormal over-expression of miR-3666 may play a key role in leukemia due to the down-regulation of PTEN.     

用通径分析法研究土壤水解酶活性与土壤性质的关系

为正确评价土壤性质对酶活性的影响程度 ,运用通径分析方法研究了浙江 5种土壤 1 2个样品中的土壤脲酶、转化酶、酸性磷酸酶活性与土壤性质的关系。结果表明 :土壤有机质、全氮、全磷是制约脲酶、转化酶和酸性磷酸酶活性的主要因素 ,而阳离子交换量对三种酶活性的影响均很微弱 ;就通径分析的直接效应而言 ,pH对脲酶活性的影响最为显著 ,对转化酶和酸性磷酸酶活性的影响程度大致相当。然而pH对脲酶、转化酶、酸性磷酸酶的这种直接效应在很大程度上被通过其它因素对三种酶的间接效应所抵消 ;土壤粉粒对转化酶活性的作用尤为显著。此外 ,粘粒对酸性磷酸酶、砂粒对脲酶有一定影响且均主要体现为直接效应。     

Extraction,molecular fractionation and enzyme degradation of organically associated phosphorus in soil solutions

The concentrations and chemical composition of water-extractable P were compared in four soil types from NE Scotland. All sites were sampled during the early establishment phase of a spring barley (Hordeum vulgare) crop. The quantity of total soluble P extracted ranged from <2.0 to 10 mg P kg soil^-1, of which up to 50% was classified as being organically associated. Sample fractionation showed that both orthophosphate inorganic P and organic P were associated with a wide molecular-size range of organic material. A strong positive correlation was readily apparent between P and the sum of Fe + Al in the fractionated samples. The extent of enzymatic hydrolysis of organic P varied between soil samples and the type of enzyme. Phytase consistently produced the greatest degree of hydrolysis.     

堆肥微生物的培养与磷酸酶活性的研究(I)——曲霉的产磷酸酶活性的研究

对培养过程中丝状真菌的产磷酸酶活性进行了比较,筛选了一株产磷酸酶活性较高的曲霉菌株HQ,对其产酶特性及对不同难溶性磷底物的磷释放量进行了研究。液体培养结果表明,该菌株在以植酸钠为底物时,中性磷酸酶活性为0.54mg m l-1,磷释放量46.65μg m l-1。固体培养结果表明,以畜禽废弃物为培养基的磷酸酶活性最高,其中性磷酸酶活性为37.4mg g-1。该菌株有潜力作为堆肥微生物的候选菌株。     

Effects of lime and phosphate additions on changes in enzyme activities,microbial biomass and levels of extractable nitrogen,sulphur and phosphorus in an acid soil

Summary The effects of adding lime and/or phosphate to an acid, phosphate-deficient soil on microbial activity, enzyme activities and levels of biomass and extractable N, S and P were studied under laboratory conditions. Following rewetting there was, as expected, an initial flush in microbial growth and activity, as shown by large increases in CO₂ evolution, in levels of biomass N, S and P and by accumulation of extractable mineral N and sulphate in the soil. Following rewetting, additions of lime and phosphate further stimulated mineralization of C, N and S. In the first 4 weeks of incubation, the mineralized N accumulated in the soil as ammonium N and there was a concomitant rise in soil pH. After this initial period, nitrification increased substantially and soil pH decreased again. Additions of lime generally increased protease and sulphatase activities but decreased phosphatase activity. Additions of phosphate decreased the activities of all three enzymes. The positive effect of liming on protease and sulphatase activities persisted for the duration of the experiment while accumulation of mineral N and sulphate effectively ceased after about 4 weeks. Furthermore, although phosphate additions decreased the activities of protease and sulphatase they increased the accumulation of mineral N and sulphate. Thus, protease and sulphatase activities were not reliable indicators of the relative amounts of mineral N and sulphate accumulated in the soil during incubation. Some uncertainty surrounded the validity of biomass S and P values estimated by the chloroform fumigation technique because differing proportions of the sulphate and phosphate released from the lysed cells may have been extracted from the different treatments.     

Enzymatic hydrolysis of organic phosphorus in extracts and resuspensions of swine manure and cattle manure

Animal manure can be a valuable resource of P for plant growth. Organic phosphates (P_o) are considered bioavailable if they can be hydrolyzed to inorganic P (P_i). Therefore, investigation of the susceptibility of manure P_o to hydrolysis may increase our understanding of manure P_o bioavailability. In this study, we demonstrate that three orthophosphate-releasing enzymes, acid phosphatase from wheat germ, alkaline phosphatase from bovine intestinal mucosa, and fungal phytase from Aspergillus ficcum, were able to hydrolyze certain amounts of P_o in animal manure. A scheme of sequential enzymatic release of P_o in manure was developed and then used to investigate changes in swine and cattle manure P distribution after storage at –20°C, 4°C or 22°C for about a year. Assuming that the P distribution in manure maintained at –20°C remained unchanged (i.e., similar to fresh manure), bioavailable P (P_i and enzyme-hydrolysable P_o) in swine manure remained relatively constant [72.8–76.3% of total P (P_t)]. Soluble but enzymatically unhydrolysable P_o (P_ue) increased from 7.2% to 32.1% of P_t during storage at 4°C. In cattle manure, bioavailable P decreased from 71.6% to 62.9% of P_t, and P_ue increased from 21.7% to 37.2% of P_t during storage at 22°C. These data indicated that the major change during the storage of animal manure for a year was the increase in P_ue, so manure P solubility may increase with storage, but the increase would not produce more bioavailable P in the manure. The effects of storage on the bioavailability of manure P should be further investigated to develop an efficient manure-P management strategy.Trade or manufacturers' names mentioned in the paper are for information only and do not constitute endorsement, recommendation, or exclusion by the USDA-ARS     

Organic phosphorus compounds as a phosphorus source for higher plants through the activity of phosphatases produced by plant roots and microorganisms

Summary The efficiency of phosphatases produced by clover, barley, oats and wheat was investigated in soils treated with sodium glycerophosphate, lecithin and phytin. Root exudates of aseptically grown clover were also examined for the breakdown of different organic P compounds in order to test the efficiency of plant-produced phosphatases. In general, the plants were able to use P from all the organic sources used in the study almost as efficiently as inorganic sources. Dry-matter yield, P uptake, acid and alkaline phosphatase activity and microbial population were increased in all the P treatments. Organic P enhanced alkaline phosphatase activity. Lecithin increased fungal, and phytin bacterial growth. There was no alkaline phosphatase activity in the asepticallly grown clover root exudates. Phosphatase released in aseptic culture after 4 weeks of clover growth was able to efficiently hydrolyse sodium glycerophosphate, lecithin and phytin. The amount of organic P hydrolysed in this and in the soil experiment surpassed plant uptake by a factor of 20. This suggests that the limiting factor on plant utilization of organic P is the availability of hydrolysable organic P sources.     

Techniques for observing phosphorus mobilization in the rhizosphere

Summary The techniques described here were developed to visualize the dissolution of sparingly soluble calcium phosphate and the presence of root-borne phosphatase in the rhizosphere. Newly formed calcium phosphate precipitate was suspended in agar containing other essential nutrients. The agar was poured into Petri dishes and acrylglass boxes and was used as a growth medium for seedlings of wheat, rape, buckwheat, and rice. With NH ₄ ⁺ applied as the N source, the precipitate dissolved in the root vicinity and this was attributed to acidification. No dissolution occurred with NO ₃ ^– as the N source. The release of a neutral phosphatase from roots was verified by embedding the roots of young seedlings in agar at pH 7 containing phenolphthalein phosphate. After pH was raised to the alkaline range by adding sodium hydroxide, the agar around the roots turned purple, especially around the roots of P-deprived plants. The most intensive phosphatase activity was found in apical root regions.     

营养环境中的酸碱反应对甜菜根际磷酸酶分泌的效应

通过对6号和10号两个甜菜品种在不同营养条件下内源磷酸酶和外源磷酸酶活性研究，得出甜菜根际酸碱度的变化对根的内源3种磷酸酶(酸性、中性和碱性磷酸酶)的活性有不同程度的影响，甜菜向根际分泌的磷酸酶的种类和量受根际pH值的影响程度因品种而异，品种间对生长介质中酸碱反应的适应能力也不同。所以。找出最佳的磷酸酶分泌pH值对甜菜生产具有现实意义。