Influence of conifers on the forms of phosphorus in selected New Zealand grassland soils

We examined the effects of conifers on the forms of P in low-fertility tussock grassland soils using ³¹P nuclear magnetic resonance (NMR) and soil P fractionation. Results from field and glasshouse experiments clearly demonstrated that conifers enhanced the mineralization of labile (and to a lesser extent more resistant) forms of soil organic P which, in turn, increased amounts of labile inorganic P in the soil. These findings have important implications for P availability and long-term sustainable management of grassland soils in New Zealand.     

Characterization of phosphorus in sub-alpine forest and adjacent grassland soils by chemical extraction and phosphorus-31 nuclear magnetic resonance spectroscopy

We used chemical extraction methods and ³¹P-nuclear magnetic resonance (NMR) to investigate the effects of vegetation on the amount and structural composition of phosphorous (P) in the sub-alpine soils of central Taiwan. Chemical extraction methods were used to measure inorganic P (Pi) and organic P (Po) in main soil horizons. The soil P composition was assessed by ³¹P-NMR spectroscopy on alkaline EDTA–NaOH extracts. According to the results of chemical extractions, the forest soil had a higher amount of Pi than the grassland soil, which might be a result of the mineralization of Po. ³¹P-NMR spectra showed inorganic orthophosphate (up to 67%) and orthophosphate monoesters (up to 75%) as the major forms of P extracted in forest and grassland soils, respectively. Smaller proportions of orthophosphate diesters and trace amounts of phosphonates and pyrophosphate were found. With possible hydrolysis of P compounds during chemical extraction and slight systemic error in the processes of extraction with NMR, the results from NMR analysis are, in general, consistent with those of chemical extraction.     

二系稻N31S／P40（F1）改变库／源比对叶片衰老及同化物分配的影响

在开花期，通过剪去１／２左右颖花和剑叶以下叶片来改变库／源比，研究了改变库／源比对二系稻Ｎ３１ｓ／Ｐ４０（Ｆ_１）剑叶光合速率，叶绿素、可溶性蛋白及的ＤＡ含量，光合同化物从剑叶的输出和在稻穗中的积累，茎鞘中糖含量的变化的影响。处理后７ｄ的光合速率差异明显，去１／２颖花量的降低光合速率，而剪叶的则提高光合速率，但处理１４ｄ后则处理间无差异。剑叶叶绿素、可溶性蛋白和ＭＤＡ含量处理间差异均不显著。因此，改变库／源比并不影响二系稻Ｎ３ＩＳ／Ｐ４０剑叶的衰老行为。但是，改变库／源比后茎鞘糖含量的变化差异明显。疏花的茎鞘可溶性糖含量高于对照，而剪叶处理的则低于对照。淀粉含量处理间差异不明显。剪叶提高乳熟期剑叶光合同化物在穗中的分配，疏花则降低在穗中的分配，但疏花提高了光合同化物在茎鞘中的分配。     

固定化31DH进行苹果酸-乳酸发酵的研究

对固定化31DH在模式酒中进行苹果酸-乳酸发酵进行了研究,结果表明:MLF结束后,以包埋量0.5ml的粒子降解苹果酸的量最多,并且产生挥发酸最少;在试验范围内,温度为15℃、pH3.1、酒精12.0%(v/v)、SO210mg/L时,苹果酸降解量最大;固定化31DH的MLE活力为6.313,游离31DH的MLE活力为3.59,前者是后者的1.76倍。     

基于31P NMR的自然成土过程中有机磷组分演变特征及影响因素研究进展

土壤有机磷(P_o)是土壤中重要的磷库,其形态、含量与生物有效性随成土过程而发生变化,进而影响土壤磷素供应、养分平衡及生态系统生产力。然而,与土壤无机磷(P_i)相比,以往的研究对P_o的重视不够,这主要是由于土壤中P_o的提取、分析和鉴定方法难于P_i。近年来,随着液相³¹P核磁共振(³¹P NMR)波谱技术在土壤学领域的应用,为定量分析土壤P_o组分及含量提供了新的技术手段,同时为更好地理解生态系统演化过程中不同形态P_o的转化特征奠定了基础。本文主要总结了土壤P_o的种类和性质,介绍了液相³¹P NMR分析土壤P_o的原理和方法,在此基础上综述了自然成土过程中不同形态P_o的转化特征及其影响因素,并指出了需进一步研究的方向和关键科学问题：包括量化成土过程中不同形态P_o转化速率、途径与环境阈值,阐明...     

施加粪肥对潮土有机磷形态转化的影响

施加粪肥是提高土壤肥力的重要措施,为了解粪肥磷在潮土中的化学行为,通过室内培养试验,采用NaOH-EDTA 浸提和 31P 核磁共振技术分析比较了鸡粪、牛粪及施肥后土壤中的磷形态及含量,并研究了施肥对潮土有效磷的影响。结果表明,粪肥磷主要以无机态形式存在,2 种粪肥的有机磷形态及含量有明显不同,肌醇六磷酸在鸡粪中的含量明显高于牛粪。粪肥施加到潮土后丰富了土壤有机磷的形态。随时间延长,潮土中各形态磷发生相互转化,以肌醇六磷酸为主的正磷酸单酯含量明显降低,核酸等正磷酸双酯显著升高。鸡粪处理的土壤有效磷含量逐渐升高,牛粪处理则表现出相反的趋势。施加粪肥后,土壤有效磷呈现不同的变化规律可能是无机磷在土壤中固定或沉淀,有机磷矿化和无机磷被微生物固持这三方面综合作用的结果。     

鸡gga-miR-31-5p 启动子真核表达载体的构建及其转录因子结合位点预测

为确定鸡gga-miR-31-5p启动子基本活性区域,并分析调控其转录的重要转录因子,初步探究影响鸡gga-miR-31-5p的表达调控机制,采用PCR法扩增鸡gga-miR-31-5p启动子,插入到pEGFP-N1载体,构建重组载体。利用菌液PCR及测序鉴定阳性重组质粒。将重组载体转染DF-1细胞系,观察其启动活性。利用在线预测网站预测gga-miR-31-5p启动子区域的转录因子结合位点。结果显示,成功克隆出gga-miR-31-5p启动子片段,并成功构建其pEGFP重组载体。体外转染结果表明,该区域具有启动活性,并发现鸡gga-miR-31-5p启动子区域存在RARα、ER、c-Jun、GR等重要转录因子结合位点。研究初步确定了鸡gga-miR-31-5p启动子区域,同时发现该区域存在重要转录因子结合位点,该结果为后续探讨进一步研究gga-miR-31-5p启动子的生物学功能奠定基础。     

玉米新品种豫玉31的丰产稳产性分析

对1997～1999年河南省玉米区试、生产试验结果分析表明,豫玉31属高产、稳产型玉米新杂交种,广泛适宜于黄淮海夏玉米区推广种植.由于其子粒品质优良,推广开发前景十分广阔。     

牛、羊布鲁菌多重PCR方法的建立与应用

根据布鲁菌属特异性基因BCSP31和布鲁菌种间特异性标志IS711插入序列,设计合成了3对引物,以牛种布鲁菌544A、104M和羊种布鲁菌16M基因组DNA为模板,通过优化反应条件,建立了可同时检测布鲁菌属、牛种布鲁菌和羊种布鲁菌的多重PCR方法。牛种布鲁菌可扩增出301和114 bp 2条带,羊种布鲁菌可扩增出301和253 bp 2条带,该方法对牛种布鲁菌544A和羊种布鲁菌16M混合DNA模板的最小检出量为100 pg,对大肠杆菌O157∶H7、小肠结肠炎耶尔森菌等15种参照菌的核酸扩增结果均为阴性。应用该方法对吉林省某牛场的106份粪便进行检测,虎红平板凝集试验作对照,结果PCR检测9份为阳性,且全为牛种布鲁菌阳性,对应的虎红平板凝集试验也为阳性。结果表明,建立的多重PCR方法具有良好的敏感性和特异性,为布鲁菌病的鉴别诊断提供了一种分子检测工具。     

Effect of deformation conditions on twinning of AZ31 magnesium alloy during compression test

Deformation twinning of homogenizing magnesium alloy AZ31 is respectively investigated by compression at room temperature with different deformation degrees from 5% to 15% and different deformation rates from 0.5 to 4mm/min.The results show that thick twins exit in a few amount of crystals at the beginning of the deformation.The thin-long twins and the thick twins appear at the end of the deformation,and they can be observed in almost all crystals.With increasing compressing rates,the yield strength,compression resistance fracture strength and density of twins increased,and twins become thin.