烤烟叶片成熟过程中钙镁铁含量的变化

田间条件下对烤烟下、中、上3个部位叶片成熟过程中钙、镁、铁元素含量的变化进行了分析。结果表明：随着烟叶部位的上升,叶片中钙、铁含量均表现为随之降低的变化规律,镁含量呈现出先降低又增加的变化;随着移栽后天数的增加,新鲜烟叶中各部位叶片钙、镁、铁含量无明显的变化规律性。3个烟叶部位之间钙、镁含量差异极显著,铁含量差异不显著;不同移栽后天数之间钙、镁、铁含量差异均不显著。移栽后天数与烟叶钙、镁、铁含量之间的相关性不显著;烟叶中钙与镁、钙与铁、镁与铁含量之间均呈极显著正相关。     

江汉平原水资源可持续利用评价

水资源系统是一个涉及自然环境、经济和社会组成的复杂系统.为了研究江汉平原水资源可持续利用的状况,通过对江汉平原水资源影响因素和供需情况的分析,建立相应的评价指标体系及等级评价模型,将众多的评价指标转化为单个综合指标,反映江汉平原水资源可持续利用的程度.通过对所收集的指标数据用SPSS软件进行预测,结果表明,江汉平原水资源2020年的可持续系数是1.017 3,即从2010年起每年以1.7％的速度增长,表明江汉平原水资源有较大的发展潜力,但部分区域仍存在不稳定因素.因此,应当采取相应的措施,加大对江汉平原水资源的保护力度,使江汉平原水资源不断向着可持续的方向发展.     

抗鸡β干扰素单克隆抗体的制备及初步鉴定

以鸡β干扰素（IFN-β）的重组蛋白pCold-ChIFN-β免疫8周龄Balb/c小鼠,采用杂交瘤技术制备抗鸡β干扰素单克隆抗体,获得两株抗鸡IFN-β的单克隆抗体。经ELISA鉴定,两株单抗的腹水效价均达到10-3以上;Western blot检测结果证明2株单克隆抗体均能与表达的鸡IFN-β发生特异性反应;其中一株单抗可检测浓度小于15 pg/mL的鸡IFN-β。本研究为检测鸡IFN-β提供了一种重要工具,也为评价鸡用疫苗的免疫效果等奠定了物质基础。     

Observing the multiexciton state in singlet fission and ensuing ultrafast multielectron transfer

Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as molecular media. Using the model system of pentacene/fullerene bilayers and femtosecond nonlinear spectroscopies, we directly observed the multiexciton (ME) state ensuing from singlet fission (a molecular manifestation of MEG) in pentacene. The data suggest that the state exists in coherent superposition with the singlet populated by optical excitation. We also found that multiple electron transfer from the ME state to the fullerene occurs on a subpicosecond time scale, which is one order of magnitude faster than that from the triplet exciton state.     

T cell receptor signaling precedes immunological synapse formation

The area of contact between a T cell and an antigen-presenting cell (APC) is known as the immunological synapse. Although its exact function is unknown, one model suggests that it allows for T cell receptor (TCR) clustering and for sustained signaling in T cells for many hours. Here we demonstrate that TCR-mediated tyrosine kinase signaling in na?ve T cells occurred primarily at the periphery of the synapse and was largely abated before mature immunological synapses had formed. These data suggest that many hours of TCR signaling are not required for T cell activation. These observations challenge current ideas about the role of immunological synapses in T cell activation.     

粒子群算法在农业水文学中的应用进展

优化问题一直是农业水文学研究的重要问题之一,而粒子群算法作为新型智能算法具有很好的寻优能力.介绍了粒子群算法的流程和步骤,以及各种改进后的粒子群算法,分析了粒子群算法在农业水资源优化配置、农田节水灌溉措施、农作物种植优化等农业水文学几个方面的应用现状.结果表明,粒子群算法在农业水文学中的应用范围有限;现有应用研究重视经济效益最大化,忽视社会生态效益;研究呈现碎片化的现象,未形成完整的学科理论体系;改进后的粒子群算法具有更好的寻优能力.指出粒子群算法与其他优化算法和技术结合将会为该算法在农业水文学中的发展开辟新的方向和道路,为农业水文学中科学问题的解决得出更好的优化结果.     

大肠埃希菌LPS感染对乌鸡脂肪代谢及相关调控基因表达的影响

【目的】研究大肠埃希菌脂多糖(LPS)感染对乌鸡脂肪代谢及相关调控基因转录表达的影响。【方法】将120只35日龄乌鸡随机分为对照组和3个试验组(低剂量LPS组、中剂量LPS组、高剂量LPS组),试验组乌鸡每48 h注射1次不同浓度的大肠埃希菌LPS生理盐水溶液,剂量为1 mL/(只.次),低、中、高剂量LPS组乌鸡的LPS用量分别为0.25,0.5,1 mg/(kg.次),对照组注射等量生理盐水,持续2周。每次注射后12 h,用温度计测量鸡只泄殖腔温度;35,42,49日龄时称鸡体质量;49日龄时,各组随机选取10只鸡翅下静脉采血,分离血清,试剂盒检测血脂指标和脂解酶的活性,然后屠宰,取胸部肌肉、腿部肌肉和腹部脂肪计算脂肪沉积率,定量PCR检测脂肪和肌肉中脂肪代谢调控基因和脂肪酸转运调控基因的转录表达情况。【结果】试验期内LPS处理组乌鸡的泄殖腔温度极显著高于对照组;与对照组相比,LPS处理组乌鸡生产性能极显著下降;脂肪沉积量减少,肌间脂肪、皮下脂肪和腹部脂肪的含量明显降低;血清中总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)浓度极显著下降,而甘油三酯(TG)、游离脂肪酸(FFA)浓度极显著升高;LPS处理组乌鸡血清中的脂蛋白脂酶、肝脂酶和脂肪酶的活性均极显著高于对照组。定量PCR检测表明,LPS处理组乌鸡肌肉和脂肪中的脂肪合成基因FAS、ACC以及控制脂肪酸氧化的CPT-ⅠmRNA水平都显著下降,且FAS/CPT-ⅠmRNA表达水平的比率明显降低;而调控脂肪分解的LPL和控制能量稳态的PPARα的mRNA水平在低剂量LPS组明显升高,但在高剂量LPS组又显著降低;LPS处理组乌鸡的脂肪酸转运调控基因FATP1、FATP4随着LPS剂量的增大而显著降低,FABP和FAT/CD36mRNA在低剂量LPS组显著升高,但随着LPS剂量升高,其表达又降低。【结论】低剂量LPS处理减弱了乌鸡体内的脂肪生成和脂肪酸的氧化,强化了脂质的分解,而高剂量LPS全面抑制了脂肪的代谢。     

Human CHN1 mutations hyperactivate alpha2-chimaerin and cause Duane's retraction syndrome

Duane's retraction syndrome (DRS) is a complex congenital eye movement disorder caused by aberrant innervation of the extraocular muscles by axons of brainstem motor neurons. Studying families with a variant form of the disorder (DURS2-DRS), we have identified causative heterozygous missense mutations in CHN1, a gene on chromosome 2q31 that encodes alpha2-chimaerin, a Rac guanosine triphosphatase-activating protein (RacGAP) signaling protein previously implicated in the pathfinding of corticospinal axons in mice. We found that these are gain-of-function mutations that increase alpha2-chimaerin RacGAP activity in vitro. Several of the mutations appeared to enhance alpha2-chimaerin translocation to the cell membrane or enhance its ability to self-associate. Expression of mutant alpha2-chimaerin constructs in chick embryos resulted in failure of oculomotor axons to innervate their target extraocular muscles. We conclude that alpha2-chimaerin has a critical developmental function in ocular motor axon pathfinding.     

The Prp19p-associated complex in spliceosome activation

During spliceosome activation, a large structural rearrangement occurs that involves the release of two small nuclear RNAs, U1 and U4, and the addition of a protein complex associated with Prp19p. We show here that the Prp19p-associated complex is required for stable association of U5 and U6 with the spliceosome after U4 is dissociated. Ultraviolet crosslinking analysis revealed the existence of two modes of base pairing between U6 and the 5' splice site, as well as a switch of such base pairing from one to the other that required the Prp19p-associated complex during spliceosome activation. Moreover, a Prp19p-dependent structural change in U6 small nuclear ribonucleoprotein particles was detected that involves destabilization of Sm-like (Lsm) proteins to bring about interactions between the Lsm binding site of U6 and the intron sequence near the 5' splice site, indicating dynamic association of Lsm with U6 and a direct role of Lsm proteins in activation of the spliceosome.