水稻白叶枯病菌GX1329基因组文库的构建及含编码TAL效应物基因的克隆的分离

由革兰氏阴性细菌水稻白叶枯病菌引起的水稻白叶枯病是亚洲、北美以及非洲部分地区最严重的水稻病害之一,水稻白叶枯病可使水稻减产高达50％以上。研究表明水稻白叶枯病菌的毒力主要依靠三型分泌系统所分泌的效应物。为了解水稻白叶枯病菌广西菌株GX1329中含有avrBs3／pthA家族基因的情况,本研究应用Alu I部分酶切其基因组DNA,构建了含有736个克隆的菌株GX1329的基因组文库。BamHI酶切分析随机挑取的15个文库克隆表明,克隆的外源DNA随机性良好,克隆的最小片段为27．7kb,最大为58．5kb,平均大小为39．9kb,文库克隆容量约为2．8×10^3Mb,该文库中包含基因组中任一个基因的概率为99．4％。利用来自水稻白叶枯病菌菲律宾菌株PX086的无毒基因avrXa10的第252位～第486位核苷酸序列作为探针,通过菌落原位杂交从GX1329基因组文库中筛选到37个含avrBs3／pthA家族基因的克隆。再通过Southern杂交分析,得到了17个独立克隆。这17个克隆中至少含有13个不同的avrBs3／pthA家族基因。这些基因在GX1329基因组中有的单独存在,有的两个或两个以上串联存在。本工作基本上明确了菌株GX1329基因组中avrBs3／pthA家族基因的数量,为进一步研究菌株GX1329中avrBs3／pthA家族基因的功能奠定了基础。     

低浓度环糊精强化Fenton试剂降解液相中茚并（1,2,3-cd）芘的试验研究

为了研究Fenton试剂对液相中茚并（1,2,3-cd）芘的降解效果,采用实验室内试验方法,考察并确定了H2O2浓度、FeSO4浓度、反应时间、pH值以及低浓度环糊精等因素对降解的影响。结果表明,使用Fenton试剂可以有效降解液相中的茚并（1,2,3-cd）芘。在降解过程中,对初始浓度为2.5mg·L-1的茚并（1,2,3-cd）芘,当H2O2浓度为20.0mmol·L-1,FeSO4浓度为3.0mmol·L-1时降解较为有效,去除率可达到62.88%,浓度过高或者过低都不利于反应的发生。Fenton氧化降解茚并（1,2,3-cd）芘的反应在60min内可以完成,并且pH值控制在3时更加有利于降解。反应体系中加入低浓度环糊精可以增加茚并（1,2,3-cd）芘在水相中的溶解度,当加入HPCD的浓度为3mg·L-1时,Fenton试剂对茚并（1,2,3-cd）芘的氧化去除率可由62.88%提高至71.24%。     

O_3浓度升高对麦季土壤-植株系统中微量元素的影响

利用O3-FACE平台研究近地面臭氧浓度升高（目标值比周围大气高50%）对2009—2010年间麦季各生育期不同深度（0～5cm,5～10cm和10～15cm）耕层土壤微量元素有效性和成熟期地上部分微量元素累积量的影响。结果表明,近地层大气O3浓度增加提高了麦季耕层（0～15cm）土壤中有效性Fe、Mn含量,降低了有效性Cu、Zn含量,对Zn的减幅达27.3%（P〈0.05）;大气O3浓度升高对土壤5～10cm土层DTPA提取态Fe、Mn、Cu、Zn的影响最大;高O3浓度显著降低了5～10cm和10～15cm土壤DTPA-Zn含量（P〈0.05）。O3浓度升高降低了小麦成熟期生物量和微量元素累积量。对不同层次土壤有效态微量元素和成熟期微量元素累积量对O3浓度升高响应进行了分析,同时指出应从土壤性质和作物生长两个方面进一步研究全球大气环境变化对土壤有效态微量元素的影响机制。     

园林植物模型在Quest3D中的应用研究

随着计算机软硬件水平的提高和可视化技术的不断发展更新,虚拟现实技术在园林中应用的领域越来越广,对园林设计的影响也越来越大。作为主流的虚拟现实软件,Quest3D在园林表现中越来越多地被应用,而园林植物对园林设计效果的表现起着重要的作用。对园林植物模型在Quest3D中的应用提出了优化的方法,以改进和完善基于Quest3D的园林虚拟漫游系统的表现效果。     

Carbon isotopic ratios of wetland and terrace soil sequences in the Maya Lowlands of Belize and Guatemala

This article provides new data and synthesizes earlier findings on the carbon isotope ratios of the humin part of soil organic matter from a range of sites in the central Maya Lowlands. Changes down the soil profile in carbon isotope ratios can provide an important line of evidence for vegetation change and erosion over time, especially in well dated aggrading profiles. Research thus far has provided substantial evidence for significant inputs from C₄ vegetation in buried layers from the Ancient Maya periods in depositional soils but equivocal evidence from sloping soils. We present new findings from soil profiles through ancient Maya wetland fields, upland karst wetlands, ancient Maya aguadas (reservoirs), and ancient Maya terraces. Most of the profiles exhibited δ¹³C enrichment greater than the 2.5–3‰ typical from bacterial fractionation. Seven of nine ancient Maya wetland profiles showed δ¹³C enrichment ranging from 4.25 to 8.56‰ in ancient Maya-dated sediments that also contained phytolith and pollen evidence of grass (C₄ species) dominance. Upland karst sinks and ancient reservoirs produced more modest results for δ¹³C enrichment. These seasonal wetland profiles exhibited δ¹³C enrichment ranging from 1 to 7.3‰ from the surface to ancient Maya-period sediments. Agricultural terraces produced mixed results, with two terraces having substantial δ¹³C enrichment of 5.34 and 5.66‰ and two producing only equivocal results of 1.88 and 3.03‰ from modern topsoils to Maya Classic-period buried soils. Altogether, these findings indicate that C₄ plants made up c. 25% of the vegetation at our sites in the Maya Classic period and only a few percent today. These findings advance the small corpus of studies from ancient terraces, karst sinks, and ancient wetland fields by demonstrating substantial δ¹³C and thus C₄ plant enrichment in soil profile sections dated to ancient Maya times. These studies are also providing a new line of evidence about local and regional soil and ecological change in this region of widespread environmental change in the Late Holocene.     

Pedogenic carbonate recrystallization assessed by isotopic labeling: a comparison of 13C and 14C tracers

The C isotopic composition (δ¹³C) of pedogenic carbonates reflects the photosynthetic pathway of the predominant local vegetation because pedogenic (secondary) CaCO₃ is formed in isotopic equilibrium with soil CO₂ released by root and rhizomicrobial respiration. Numerous studies show the importance of pedogenic carbonates as a tool for reconstructing paleoecological conditions in arid and semiarid regions. The methodological resolution of these studies strongly depends on the time scale of pedogenic carbonate formation, which remains unknown. The initial formation rate can be assessed by ¹⁴C labeling of plants grown on loess and subsequent incorporation of ¹⁴C from rhizosphere CO₂ into newly formed carbonate by recrystallization of loess CaCO₃. We tested the feasibility of ¹⁴C and ¹³C tracers for estimating CaCO₃ recrystallization rates by simultaneous ¹⁴C and ¹³C labeling and comparison with literature data. ¹⁴C labeling was more efficient and precise in assessing recrystallization rates than ¹³C labeling. This is connected with higher sensitivity of ¹⁴C liquid scintillation counting when compared with δ¹³C measurement by IRMS. Further, assessment of very low amounts of incorporated tracer is more precise with low background signal (natural abundance), which is true for ¹⁴C, but is rather high for ¹³C. Together, we obtained better reproducibility, higher methodological precision, and better plausibility of recrystallization rates calculated based on ¹⁴C labeling. Periods for complete CaCO₃ recrystallization, extrapolated from rates based on ¹⁴C labeling, ranged from 130 (125–140) to 240 (225–255) y, while it was ≈ 600 (365–1600) y based on the ¹³C approach. In terms of magnitude, data from late‐Holocene soil profiles of known age provide better fit with modeled recrystallization periods based on the ¹⁴C approach.     

基于ZigBee和嵌入式技术的无线安防监控系统研究与设计

针对传统有线安防系统的局限性,通过对zigbee技术和嵌入式技术的研究,提出了一种基于zigbee组网技术和嵌入式控制技术的住宅小区无线安防监控系统,实现了布防后能够对住宅小区生活中存在的火灾、盗窃、煤气泄漏等安全隐患进行监测及报警。采用基于ZigBee标准的射频芯片CC2430,实现节点间数据的无线传输,并给出了系统的硬件原理框图和软件设计思路。     

包膜控释尿素（追施）对冬小麦生长发育及土壤硝态氮含量的影响

通过田间试验,研究了苗期和返青期追施释放期为30d和60d的包膜控释尿素对冬小麦生长发育及土壤硝态氮含量的影响。结果表明,分别在冬小麦苗期和返青期追施释放期为60d包膜控释尿素（N60N60）,能显著促进植株生长发育,增强植株对N、P、K养分吸收,增加籽粒产量。与不追肥（CK）处理相比,N60N60处理植株地上部和地下部干物重分别提高33.21%和67.84%;叶片叶绿素含量增加12.77%～25.20%;植株茎叶N、P、K含量分别增加63.55%、37.08%和6.91%,籽粒N、P、K含量分别增加8.56%、31.18%和24.49%;小麦穗长、穗粒重、千粒重和籽粒产量分别增加14.14%、27.00%、39.32%和48.01%。在返青期追施1次包膜控释尿素,N0N30优于N0N60处理,叶绿素含量增加1.50%～3.04%;植株茎叶N、P、K含量分别增加12.37%、12.25%和1.26%,籽粒N、P、K含量分别增加0.50%、5.69%和9.74%;小麦穗长、穗粒重、千粒重和籽粒产量分别增加2.84%、11.81%、11.65%和6.61%。同时,包膜控释尿素施用能明显减少硝态氮向土壤深层渗漏数量,减轻对地下水污染风险。     

家蚕3-羟酰辅酶A脱氢酶基因全长cDNA克隆及其在质型多角体病毒感染家蚕的差异表达

家蚕质型多角体病毒（Bombyx mori cytoplasmic polyhedrosis virus,BmCPV）是家蚕的重要病毒病原之一,往往给养蚕业生产造成极大危害。我们以前的研究运用基因芯片技术在感染质型多角体病毒的家蚕中肠中鉴定出一个差异表达的3-羟酰辅酶A脱氢酶蛋白基因（Bombyx mori3-hydroxyacyl-CoA dehyrogenase protein gene-Bm3HAD）。本研究利用cDNA末端快速扩增技术（RACE）克隆了该基因,其全长cDNA序列为1168bp,包含一个83bp5＇端非翻译区序列（5＇-UTR）、一个930bp的开放阅读框（ORF）和一个155bp的3＇端非翻译区序列（3＇-UTR）;基因结构分析发现该基因由5个外显子和4个内含子组成。RT-PCR结果显示该基因在家蚕中肠、脂肪体、血液、丝腺及生殖体中均有表达。荧光定量PCR结果表明该基因在BmCPV感染初期为上调表达,随着病毒感染的进展,该基因的表达水平逐渐降低,并转变为下调表达。研究结果为进一步研究BmCPV对家蚕致病的分子机制提供了有益的信息。     

福建菜田氮磷积累状况及其淋失潜力研究

本文通过采集460个福建菜田代表性耕层土样,采用土壤测试和土柱渗漏水模拟试验的方法研究菜田土壤硝态氮和Olsen P含量状况和淋失临界指标及其淋失潜力。结果表明,耕层土壤硝态氮含量为47.455.5 mg/kg,Olsen-P含量则为61.743.2 mg/kg, 其中瓜果类蔬菜种植地土壤硝态氮和Olsen-P含量明显高于叶菜类和根茎类蔬菜种植地。 应用双速率转折点建模法,得到氮、 磷淋失临界指标X0分别为土壤硝态氮76.3 mg/kg和Olsen-P 42.8 mg/kg。 淋失临界值相当于或略高于满足蔬菜营养的农学指标。当土壤硝态氮或Olsen-P含量低于X0时,随着其含量增加,渗漏水硝态氮或总磷浓度以线性方式缓慢增加,反之,则以非线性形式急剧增大。土壤硝态氮和Olsen-P含量高于其X0的土样数分别占17.9%和81.3%, 表明这些样点具有较高的氮、 磷淋失潜力,是氮、 磷污染控制的关键地块。 瓜果类菜田土壤硝态氮和Olsen-P含量高于其X0的土样数分别占到32.3%和96.3%,淋失潜力明显高于叶菜类和根茎类菜田,是氮、 磷污染控制的优先区域。