Recognition of histone H3 lysine-4 methylation by the double tudor domain of JMJD2A

Biological responses to histone methylation critically depend on the faithful readout and transduction of the methyl-lysine signal by "effector" proteins, yet our understanding of methyl-lysine recognition has so far been limited to the study of histone binding by chromodomain and WD40-repeat proteins. The double tudor domain of JMJD2A, a Jmjc domain-containing histone demethylase, binds methylated histone H3-K4 and H4-K20. We found that the double tudor domain has an interdigitated structure, and the unusual fold is required for its ability to bind methylated histone tails. The cocrystal structure of the JMJD2A double tudor domain with a trimethylated H3-K4 peptide reveals that the trimethyl-K4 is bound in a cage of three aromatic residues, two of which are from the tudor-2 motif, whereas the binding specificity is determined by side-chain interactions involving amino acids from the tudor-1 motif. Our study provides mechanistic insights into recognition of methylated histone tails by tudor domains and reveals the structural intricacy of methyl-lysine recognition by two closely spaced effector domains.     

α?芋螺毒素LvIA第11位氨基酸的新突变体合成及其靶点活性

为了进一步探究第11位氨基酸的性质对LvIA靶点结合活性的影响，设计了LvIA的2个新型突变体[D11R]LvIA和[D11H]LvIA，即用2个碱性氨基酸?精氨酸（R）和组氨酸（H）分别替换原来的酸性氨基酸D。先人工合成了这2个新突变体的线性肽，然后采用2步氧化法进行折叠，以获得在第1位和第3位半胱氨酸（Cys 1～3）、第2位和第4位半胱氨酸（Cys 2～4）之间定点连接形成二硫键。经高效液相色谱分离纯化和质谱鉴定，合成了含有Cys(1～3, 2～4)二硫键连接方式的多肽，其分子质量正确，纯度在95%以上。利用双电极电压钳电生理学技术对这2种突变体与α3β2 nAChR的结合活性进行了检测。结果发现，当该位点的氨基酸性质由酸性转换为碱性后，对LvIA的活性影响巨大，直接导致对α3β2 nAChR的阻断活性丧失。[D11R]LvIA和[D11H]LvIA的活性与野生型LvIA相比分别降低了574.38%和408.62%。由此表明，第11位氨基酸的酸碱性对LvIA的活性至关重要。     

黄烷酮3-羟化酶基因表达分析及转基因大豆新种质创制

黄烷酮3-羟化酶(F3H)是大豆异黄酮代谢途径重要酶类。研究F3H在不同大豆品种中的表达差异,并应用转基因途径创制新种质是提高大豆异黄酮含量的重要途径。以高异黄酮含量大豆品种中豆27和低异黄酮含量大豆品种楚秀为试材,采用q PCR技术,分析F3H在大豆不同发育时期、组织部位中的表达差异;并利用花粉管通道转化技术,获得转F3H阳性植株。结果表明:F3H在2个大豆品种R1~R7期叶片中的表达模式不同,中豆27的F3H表达量在R1期最高,而后开始下降,R2~R5期维持较低水平,R6期略有上升,R7期又出现下降;楚秀F3H表达量在R1~R4期较低,R5期出现表达高峰,R6期开始下降。F3H在2个大豆品种R5~R8期籽粒中的表达模式基本相同,表达量均从R5期开始下降,且R6~R8期维持较低水平。基于此,构建F3H RNAi反义载体,并利用花粉管通道技术转入不同大豆品种,获得了5个转基因新材料。     

两种刺玫花粉离体萌发培养液配方的优化

以报春刺玫(Rosa primula)和单瓣黄刺玫(R.xanthina)储存花粉为材料,设计单因素试验和正交试验,考察了蔗糖、硼酸及Ca(NO3)2.4H2O浓度对两种刺玫花粉萌发率的影响。结果表明,适宜浓度的蔗糖和硼酸能促进花粉萌发,而较高浓度的Ca(NO3)2.4H2O会抑制花粉萌发。正交试验结果表明适合报春刺玫花粉萌发的最佳培养基为20%蔗糖(质量分数,下同)+100 mg/L硼酸;适合单瓣黄刺玫花粉萌发的最佳培养基为10%蔗糖+50 mg/L硼酸。     

Catalytic reduction of dinitrogen to ammonia at a single molybdenum center

Dinitrogen (N2) was reduced to ammonia at room temperature and 1 atmosphere with molybdenum catalysts that contain tetradentate [HIPTN3N]3- triamidoamine ligands (such as [HIPTN3N]Mo(N2), where [HIPTN3N]3- is [(3,5-(2,4,6-i-Pr3C6H2)2C6H3NCH2CH2)3N]3-) in heptane. Slow addition of the proton source [(2,6-lutidinium)(BAr'4), where Ar' is 3,5-(CF3)2C6H3]and reductant (decamethyl chromocene) was critical for achieving high efficiency ( approximately 66% in four turnovers). Numerous x-ray studies, along with isolation and characterization of six proposed intermediates in the catalytic reaction under noncatalytic conditions, suggest that N2 was reduced at a sterically protected, single molybdenum center that cycled from Mo(III) through Mo(VI) states.     

Hot Plasma and Energetic Particles in Neptune's Magnetosphere

The low-energy charged particle (LECP) instrument on Voyager 2 measured within the magnetosphere of Neptune energetic electrons (22 kiloelectron volts /=0.5 MeV per nucleon) energies, using an array of solid-state detectors in various configurations. The results obtained so far may be summarized as follows: (i) A variety of intensity, spectral, and anisotropy features suggest that the satellite Triton is important in controlling the outer regions of the Neptunian magnetosphere. These features include the absence of higher energy (>/=150 keV) ions or electrons outside 14.4 R(N) (where R(N) = radius of Neptune), a relative peak in the spectral index of low-energy electrons at Triton's radial distance, and a change of the proton spectrum from a power law with gamma >/= 3.8 outside, to a hot Maxwellian (kT [unknown] 55 keV) inside the satellite's orbit. (ii) Intensities decrease sharply at all energies near the time of closest approach, the decreases being most extended in time at the highest energies, reminiscent of a spacecraft's traversal of Earth's polar regions at low altitudes; simultaneously, several spikes of spectrally soft electrons and protons were seen (power input approximately 5 x 10(-4) ergs cm(-2) s(-1)) suggestive of auroral processes at Neptune. (iii) Composition measurements revealed the presence of H, H(2), and He(4), with relative abundances of 1300:1:0.1, suggesting a Neptunian ionospheric source for the trapped particle population. (iv) Plasma pressures at E >/= 28 keV are maximum at the magnetic equator with beta approximately 0.2, suggestive of a relatively empty magnetosphere, similar to that of Uranus. (v) A potential signature of satellite 1989N1 was seen, both inbound and outbound; other possible signatures of the moons and rings are evident in the data but cannot be positively identified in the absence of an accurate magnetic-field model close to the planet. Other results indude the absence of upstream ion increases or energetic neutrals [particle intensity (j) < 2.8 x 10(-3) cm(-2) s(-1) keV(-1) near 35 keV, at approximately 40 R(N)] implying an upper limit to the volume-averaged atomic H density at R 22 keV) input on Neptune is approximately 3 x 10(7) W, surprisingly small when compared to energy input into the atmosphere of Jupiter, Saturn, and Uranus.     

烤烟烟叶成熟度与香气质量的关系

以河南产烤烟为试材，研究了烤烟烟叶成熟度与香气质量关系。结果显示：1)烟叶中主要香气成分的含量随烤烟成熟度的提高而增加，如3-甲基-2-乙酰苯酚、香叶基香叶二烯、(1S，2E，4R,6R，7E,11S)-2,7,12-西柏三烯-4，6-二醇、10-异丙基-3，7，13-三甲基-2，6，11，13-十四碳四烯-1-醇、巨豆-4，6(E)。8(E)-三烯酮-3、十四碳酸等，在烟叶充分成熟阶段达到最大值，之后开始缓慢下降；2)烟碱、十六碳酸、(1S、2E、4R、6R、7E、11S)-2,7,12-西柏三烯-4，6，11-三醇、(1S，2E，4R，6R，7E，11S)-8，11-氧撑-2，6,12-西柏三烯-4-醇等香气成分含量则随着成熟度的提高持续增加，最大值出现在过熟阶段；3)2-呋喃甲醛、2-甲基苯甲醛、1-乙基环己烯、1，2-苯二甲酸异丁正丁酯、巨豆-4．6(Z)，8(Z)-三烯酮-3等香气成分含量随着成熟度提高呈稳定下降趋势；4)成熟时烟叶的糖含量高。总氮、烟碱含量适宜，各种化学比值协调，烟叶香气量足，香气质好，杂气、刺激性明显减轻，总体香吃味质量最好，而成熟不够或者过熟的烟叶．其内在质量明显降低。     

柳叶拟沉香中乙酰胆碱酯酶的抑制活性成分

采用ODS、硅胶、Sephadex LH-20等柱色谱技术从瑞香科(Thymelaeaceae)拟沉香属(Gyrinops)植物柳叶拟沉香(Gyrinops salicifolia Ridl)分离得到9个2-(2-苯乙基)色酮类化合物,运用波谱学方法鉴定其结构,并采用Elman比色法对全部化合物进行活性测试。结果表明,柳叶拟沉香中分离的化合物结构分别为:6-羟基-2-(2-苯乙基)色酮(化合物1)、6-羟基-2-[2-(4-甲氧基苯)乙基]色酮(化合物2)、6,8-二羟基-2-[2-(4-甲氧基苯)乙基]色酮(化合物3)、6-甲氧基-2-[2-(3-甲氧基-4-羟基苯)乙基]色酮(化合物4)、6-羟基-7-甲氧基-2-[2-(4-甲氧基苯)乙基]色酮(化合物5)、(5R,6R,7S,8R)-5,6,7,8-四氢-5,6,7,8-四羟基-2-(2-苯乙基)-4氢-色酮(化合物6)、5α,6β,7β-三羟基-8α-甲氧基-2-(2-苯乙基)-4氢-色酮(化合物7)、(5S,6S,7S,8R)-2-[2-(4-甲氧基苯)乙基]-5,6,7,8-四羟基-5,6,7,8-4氢-色酮(化合物8)和8-氯-6-羟基-2-(2-苯乙基)色酮(化合物9)。从拟沉香属植物所产沉香中分离得到以上化合物均未见报道。化合物2,4,8,9对乙酰胆碱酯酶具有一定的抑制活性。     

Infrared observations of the saturnian system from voyager 1

During the passage of Voyager 1 through the Saturn system, the infrared instrument acquired spectral and radiometric data on Saturn, the rings, and Titan and other satellites. Infrared spectra of Saturn indicate the presence of H(2), CH(4), NH(3), PH(3), C(2)H(2), C(2)H(6), and possibly C(3)H(4) and C(3)H(8). A hydrogen mole fraction of 0.94 is inferred with an uncertainty of a few percent, implying a depletion of helium in the atmosphere of Saturn relative to that of Jupiter. The atmospheric thermal structure of Saturn shows hemisphere asymmetries that are consistent with a response to the seasonally varying insolation. Extensive small-scale latitudinal structure is also observed. On Titan, positive identifications of infrared spectral features are made for CH(4), C(2)H(2), C(2)H(4), C(2)H(6), and HCN; tentative identifications are made for C(3)H(4) and C(3)H(8). The infrared continuum opacity on Titan appears to be quite small between 500 and 600 cm(-1), implying that the solid surface is a major contributor to the observed emission over this spectral range; between 500 and 200 cm(-1) theopacity increases with decreasing wave number, attaining an optical thickness in excess of 2 at 200 cm(-1). Temperatures near the 1-millibar level are independent of longitude and local time but show a decrease of approximately 20 K between the equator and north pole, which suggests a seasonally dependent cyclostrophic zonal flow in the stratosphere of approximately 100 meters per second. Measurements of the C ring of Saturn yield a temperature of 85 +/- 1 K and an infrared optical depth of 0.09 +/- 0.01. Radiometer observations of sunlight transmitted through the ring system indicate an optical depth of 10(-1.3 +/-0.3) for the Cassini division. A phase integral of 1.02 +/- 0.06 is inferred for Rhea, which agrees with values for other icy bodies in the solar system. Rhea eclipse observations indicate the presence of surface materials with both high and low thermal inertias, the former most likely a blocky component and the latter a frost.     

解磷菌株黑曲霉PSFM发酵条件优化研究

【目的】利用液体培养法探究不同碳源、氮源、无机盐和微量元素浓度以及发酵时间、温度、初始pH、转速、接种量等条件对解磷菌解磷特性的影响,获得解磷菌的最佳发酵培养基和培养条件。【方法】采用单因素及正交试验法,对一株分离自土壤的解磷真菌黑曲霉（Aspergillus niger）PSFM菌株的基础发酵培养基和发酵条件（发酵时间0～10d、温度20～40℃、初始pH值3.0～11.0、接种量1%～11%、转速120～300rpm）进行优化,测定其发酵液吸光度值,以解磷量的高低作为评价发酵培养基及发酵条件优劣的指标。【结果】分别在无机磷和有机磷液体培养基、简单培养基（SP）、NBRIY、NBRIP、NBRIYP培养基中培养6d后,以无机磷液体培养基的PSFM菌株解磷能力最高,解磷量为526.42mg/L。在12种不同碳源培养基中,PSFM均能正常生长,其解磷能力由大到小依次为：木糖〉葡萄糖〉乳糖〉蔗糖〉麦芽糖〉半乳糖〉山梨糖〉甘露糖〉果糖〉可溶性淀粉〉鼠李糖〉甘油。以硝酸钠、尿素、酵母浸膏、氯化铵、硝酸镁、硝酸铵、色氨酸、乙酸铵、牛肉浸膏、胰-蛋白胨、甘氨酸、酪氨酸、丙氨酸和精氨酸为氮源时,硫酸铵为唯一氮源的解磷效果最好,菌株PSFM发酵液中有效磷含量最高（990.31mg/L）。菌株PSFM的解磷能力均随着最佳培养基中NaCl、KCl、MgSO4·7H2O、FeSO4·7H2O和MnSO4·7H2O浓度的增加呈先提高后降低趋势,当其浓度分别为0.03%、0.01%、0.03%、0.001%、0.001%时,菌株PSFM的解磷能力均最强。在不同发酵条件下,以发酵6d、温度28℃、初始pH6.0、5%接种量、转速300rpm的PSFM解磷能力最强,解磷量分别为599.24、528.23、603.69、530.57和731.48mg/L。【结论】最适合PSFM菌株的基础发酵培养基为无机磷液体培养基,碳源为1.0%木糖,氮源为0.10%硫酸铵,最佳无机盐配方为：NaCl0.10g/L、KCl0.70g/L、MgSO·47H2O 0.70g/L、FeSO4·7H2O 0.01g/L、MnSO·47H2O 0.01g/L;最佳培养条件为：温度28℃,初始pH6.0,转速180rpm,接种量5%,发酵时间为6d。     

黎药光叶巴豆枝叶的化学成分分析

为研究光叶巴豆枝叶的化学成分,笔者采用硅胶柱色谱、Sephadex LH-20、半制备高效液相色谱等多种色谱技术进行化合物的分离纯化,通过化合物的波谱数据和理化性质鉴定其结构.从光叶巴豆枝叶95％乙醇提取物中分离得到12个化合物,分别鉴定为:(3S,5R,6S,7E,9R)-3,6-dihydroxy-5,6-dihy...     

A liquid-solution-phase synthesis of crystalline silicon

A liquid-solution-phase technique for preparing submicrometer-sized silicon single crystals is presented. The synthesis is based on the reduction of SiCl(4) and RSiCl(3) (R = H, octyl) by sodium metal in a nonpolar organic solvent at high temperatures (385 degrees C) and high pressures (> 100 atmospheres). For R = H, the synthesis produces hexagonal-shaped silicon single crystals ranging from 5 to 3000 nanometers in size. For R = octyl, the synthesis also produces hexagonal-shaped silicon single crystals; however, the size range is controlled to 5.5 +/- 2.5 nanometers.     

打孔塞入法治疗果树缺铁黄叶病

为了经济、安全、高效地治疗果树因缺铁而引发的黄叶病,克服目前土壤和叶面施铁疗效差,树干注射复绿剂受季节限制、安全性差、操作复杂的缺陷,选用4类8种含Fe化合物(易溶性二价无机铁盐FeSO4.7H2O和FeCl2.4H2O,易溶性三价无机铁盐Fe2(SO4)3和FeCl3.6H2O,难溶性Fe2O3和FeC2O4,铁络合物Fe(NH4)2(SO4)2.6H2O和FeC6O7H6),在树干上打孔后将其塞入。结果表明,多种含铁化合物都能使果树缺铁黄化病在第6至第7天开始复绿,20d后使已经白化的叶片也能彻底恢复绿色,其中Fe(NH4)2(SO4)2.6H2O最为经济、安全、高效,FeSO4.7H2O次之。     

广东樟树各器官含碳率及碳储量

以2012年广东省森林资源连续清查资源数据中樟树Cinnamomum camphora的分布为基础,按2,4,6,8,12,16,20,26,32和38 cm共10个径阶伐倒90株樟树样木,获取树干、树皮、树叶、树枝、树根各器官生物量及含碳率数据,采用加权平均和总碳储量计算方法,计算了90株单木的碳储量。结果表明:广东樟树平均含碳率为0.509 6;树皮含碳率显著低于其他各器官（P < 0.05）,树干、树叶、树枝、树根差异不显著;含碳率随年龄增加而增加,到近熟林和成熟林达到最高,到过熟林再下降;人工林的含碳率高于天然林;含碳率随着纬度增加而增加,随着海拔增加而降低;各器官碳储量在全树中的比例从大到小排列顺序为树干,树枝,树根,树皮,树叶;随着胸径增加树干碳储量比例变化的趋势先增加后下降,树皮碳储量比例前期稳定、后期下降,树叶、树根碳储量比例变化不大,树枝碳储量比例初期稳定、后期增加。拟合出樟树年龄（A）,胸径（D）和D2H（H为树高）的最优碳储量（C_t）模型依次为C_t=0.019 4A2.652 0,C_t=0.011 8D2.937 6,C_t=0.001 6（D2H）1.268 6,R2值依次为0.602 9,0.943 2,0.910 5;经交叉检验,模型拟合效果显著（P < 0.01）。以胸径和D2H为变量的樟树碳储量模型拟合效果优于以年龄为变量的模型,模型应用中应优先选择胸径和D2H为变量的模型进行碳储量估算,当胸径和D2H不易测量且年龄易知时,方可使用年龄为变量的碳储量模型进行估算。     

Reversible, metal-free hydrogen activation

Although reversible covalent activation of molecular hydrogen (H2) is a common reaction at transition metal centers, it has proven elusive in compounds of the lighter elements. We report that the compound (C6H2Me3)2PH(C6F4)BH(C6F5)2 (Me, methyl), which we derived through an unusual reaction involving dimesitylphosphine substitution at a para carbon of tris(pentafluorophenyl) borane, cleanly loses H2 at temperatures above 100 degrees C. Preliminary kinetic studies reveal this process to be first order. Remarkably, the dehydrogenated product (C6H2Me3)2P(C6F4)B(C6F5)2 is stable and reacts with 1 atmosphere of H2 at 25 degrees C to reform the starting complex. Deuteration studies were also carried out to probe the mechanism.     

Resistance of barley varieties to Heterodera avenae in the Qinghai–Tibet Plateau,China

The cereal cyst nematode, Heterodera avenae, is one of the most economically important pathogens impacting the worldwide production of cereals and is widely distributed in more than 16 regions in China. The present study used the numbers of nematodes inside the plant roots to evaluate the resistance/susceptibility of different subpopulations of barley Hordeum vulgare (QH2R, QH6R and TB2R) to H. avenae under field and pot conditions. Nematode development in two highly resistant varieties was also evaluated by in vivo experiment and microscopic observation. Analyses of 186 selected varieties showed the numbers of susceptible varieties identified with the number of females/cysts per plant (NFP) method were significantly higher than those identified with the Pf/Pi ratio (PPR) method, which indicated that the NFP method rather than the PPR method is more reliable to evaluate the resistance of barley. The field and pot experiment results indicated that the QH2R subpopulation had lower females/cysts numbers than QH6R and TB2R subpopulations, and eight HR varieties (Sunong 7617, Sunong 7635, Dongyuan 87-14, Rudong 14-46, Rudong 87-57, Rudong 87-8-45, Rudong 88-14-2, and Rudong 88-67-1) were identified in QH2R, with the NFP numbers below 4.2. Further microscopic observation of nematode development suggested that H. avenae often penetrated less into highly resistant varieties (Sunong 7635 and Dongyuan 87-14) and more frequently failed to develop into females than the susceptible barleys. The promising resistant varieties identified in the present research might be helpful for breeders to develop CCN-resistant cultivars and control H. avenae populations effectively at low costs.     

解磷菌株黑曲霉PSFM发酵条件优化研究

【目的】利用液体培养法探究不同碳源、氮源、无机盐和微量元素浓度以及发酵时间、温度、初始pH、转速、接种量等条件对解磷菌解磷特性的影响,获得解磷菌的最佳发酵培养基和培养条件。【方法】采用单因素及正交试验法,对一株分离自土壤的解磷真菌黑曲霉（Aspergillus niger）PSFM菌株的基础发酵培养基和发酵条件（发酵时间0～10 d、温度20～40℃、初始pH值3.0～11.0、接种量1%～11%、转速120～300 rpm）进行优化,测定其发酵液吸光度值,以解磷量的高低作为评价发酵培养基及发酵条件优劣的指标。【结果】分别在无机磷和有机磷液体培养基、简单培养基（SP）、NBRIY、NBRIP、NBRIYP培养基中培养6 d后,以无机磷液体培养基的PSFM菌株解磷能力最高,解磷量为526.42 mg/L。在12种不同碳源培养基中,PSFM均能正常生长,其解磷能力由大到小依次为：木糖＞葡萄糖＞乳糖＞蔗糖＞麦芽糖＞半乳糖＞山梨糖＞甘露糖＞果糖＞可溶性淀粉＞鼠李糖＞甘油。以硝酸钠、尿素、酵母浸膏、氯化铵、硝酸镁、硝酸铵、色氨酸、乙酸铵、牛肉浸膏、胰-蛋白胨、甘氨酸、酪氨酸、丙氨酸和精氨酸为氮源时,硫酸铵为唯一氮源的解磷效果最好,菌株PSFM发酵液中有效磷含量最高（990.31 mg/L）。菌株PSFM的解磷能力均随着最佳培养基中NaCl、KCl、MgSO4·7H2O、FeSO4·7H2O和MnSO4·7H2O浓度的增加呈先提高后降低趋势,当其浓度分别为0.03%、0.01%、0.03%、0.001%、0.001%时,菌株PSFM的解磷能力均最强。在不同发酵条件下,以发酵6 d、温度28℃、初始pH 6.0、5%接种量、转速300 rpm的PSFM解磷能力最强,解磷量分别为599.24、528.23、603.69、530.57和731.48 mg/L。【结论】最适合PSFM菌株的基础发酵培养基为无机磷液体培养基,碳源为1.0%木糖,氮源为0.10%硫酸铵,最佳无机盐配方为：NaCl 0.10 g/L、KCl 0.70 g/L、MgSO4·7H2O 0.70 g/L、FeSO4·7H2O 0.01 g/L、MnSO4·7H2O 0.01 g/L;最佳培养条件为：温度28℃,初始pH 6.0,转速180 rpm,接种量5％,发酵时间为6 d。     

Diverse plasma populations and structures in Jupiter's magnetotail

Jupiter's magnetotail is the largest cohesive structure in the solar system and marks the loss of vast numbers of heavy ions from the Jupiter system. The New Horizons spacecraft traversed the magnetotail to distances exceeding 2500 jovian radii (R(J)) and revealed a remarkable diversity of plasma populations and structures throughout its length. Ions evolve from a hot plasma disk distribution at approximately 100 R(J) to slower, persistent flows down the tail that become increasingly variable in flux and mean energy. The plasma is highly structured-exhibiting sharp breaks, smooth variations, and apparent plasmoids-and contains ions from both Io and Jupiter's ionosphere with intense bursts of H(+) and H(+)(3). Quasi-periodic changes were seen in flux at approximately 450 and approximately 1500 R(J) with a 10-hour period. Other variations in flow speed at approximately 600 to 1000 R(J) with a 3- to 4-day period may be attributable to plasmoids moving down the tail.