斑鸠对H9N2亚型禽流感病毒的易感性及其流感病毒受体类型的研究

【目的】验证斑鸠对H9N2亚型禽流感病毒的易感性,测定斑鸠呼吸道上皮细胞表面流感病毒受体的类型和分布。【方法】以5×104EID50/只的剂量经滴鼻、点眼途径感染A/Chicken/Beijing/2/2009（H9N2）亚型禽流感病毒,共感染8只斑鸠和8只SPF鸡,对试验斑鸠和SPF鸡进行临床症状、大体病变、组织学病变的观察及病毒抗原的定位、病毒分离和感染抗体的测定。【结果】攻毒后5d,斑鸠和SPF鸡未见异常临床表现和大体病变,病理组织学检查发现斑鸠的喉头、气管上段、中段和下段上皮细胞均有不同程度的脱落;在斑鸠的喉头、气管上段、中段和下段上皮细胞的胞浆内检测到了大量阳性流感病毒蛋白颗粒;斑鸠咽拭子病毒分离阳性率为75%（6/8）,SPF鸡咽拭子病毒分离阳性率为100%（8/8）。攻毒后14d,斑鸠H9N2亚型禽流感病毒HI抗体阳性率为80%（4/5）,SPF鸡HI抗体阳性率为100%（5/5）。对H9N2亚型禽流感病毒受体检测结果表明,斑鸠的喉头、气管上段、中段、下段上皮细胞表面存在SAα2, 3Gal和SAα2, 6Gal两种连接键型的受体。【结论】斑鸠对H9N2亚型禽流感病毒A/Chicken/Beijing/2/2009（H9N2）易感,且斑鸠的喉头和气管上、中、下段上皮细胞表面同时存在能够与禽流感病毒结合的SAα2, 3Gal受体和与人流感病毒结合的SAα2, 6Gal受体。     

鸡、鸽、虎呼吸道和消化道黏膜上皮细胞表面流感病毒受体类型的检测

 【目的】检测鸡、鸽和虎体内的流感病毒受体的类型和分布,以期解释3种动物对禽流感病毒易感性差异的机制。【方法】使用地高辛标记的外源性凝集素染色方法检测这些动物的喉头、气管、肺脏和肠道（直肠）的上皮细胞表面SAα2,6Gal和SAα2,3Gal连接键的类型。【结果】SPF鸡的上呼吸道黏膜上皮细胞表面有大量的SAα2,3Gal和少量的SAα2,6Gal;肺房上皮细胞表面只有SAα2,3Gal;而直肠黏膜上皮中SAα2,6Gal和SAα2,3Gal都没有表达。成年鸽的上呼吸道黏膜上皮细胞表面只有SAα2,6Gal,而没有SAα2,3Gal;而下呼吸道中SAα2,6Gal和SAα2,3Gal都没有;直肠黏膜上皮细胞只有SAα2,3Gal。虎的呼吸道和消化道（直肠）黏膜上皮细胞表面有大量的SAα2,6Gal和SAα2,3Gal。【结论】鸡和虎具有禽流感病毒受体,对禽流感病毒易感,鸽不具备禽流感病毒受体,因此,鸽对禽流感病毒不易感。     

Microsomal N-demethylation, by a cotton leaf oxidase system, of 3-(4'-chloropENYL)-1, 1-dimethylurea (monuron)

A cotton leaf microsomal oxidase system that N-demethylates 3-(4'-chlorophenyl)-1,1-dimethylurea (monuron) to 3-(4'-chlorophenyl)-1-methylurea has been partially characterized. The enzyme system is associated with a microsomal fraction separated by differential centrifugation and requires molecular oxygen as well as either the reduced form of nicotinamide adenine dinucleotide phosphate or the reduced form of nicotinamide adenine dinucleotide as cofactors.     

Mantle plume helium in submarine basalts from the galapagos platform

Helium-3/helium-4 ratios in submarine basalt glasses from the Galapagos Archipelago range up to 23 times the atmospheric ratio in the west and southwest. These results indicate the presence of a relatively undegassed mantle plume at the Galápagos hot spot and place Galápagos alongside Hawaii, Iceland, and Samoa as the only localities known to have such high helium-3/helium-4 ratios. Lower ratios across the rest of the Galápagos Archipelago reflect systematic variations in the degree of dilution of the plume by entrainment of depleted material from the asthenosphere. These spatial variations reveal the dynamics of the underlying mantle plume and its interaction with the nearby Galápagos Spreading Center.     

A glycolipid antigen associated with Burkitt lymphoma defined by a monoclonal antibody

The antigen defined by a rat monoclonal antibody directed to a Burkitt lymphoma cell line was identified as globotriaosylceramide [Gal alpha (1 leads to 4)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide]. The antibody demonstrated a strict steric specificity since it did not react with globoisotriaosylceramide [Gal alpha (1 leads to 3)-Gal beta (1 leads to 4)-Glc beta (1 leads to 1)-ceramide], the positional isomer of the antigen associated with the Burkitt lymphoma. Chemical analysis of various Burkitt lymphoma cell lines revealed that the Burkitt lymphoma cells contained more than 100 times as much of the glycolipid antigen as was found in other human lymphoma and leukemia cell lines.     

Potassium-argon ages from the galapagos islands

Potassium-argon ages of eight volcanic rocks from some of the geologically oldest flows exposed in the Galápagos Archipelago indicate that the Galápagos Islands have a probable maximum age of 3 million years. Rocks from six islands were dated; the oldest are from Espa?ola (3.2 +/- 0.2), Sante Fe (2.7 +/- 0.1), and Plazas (4.2 +/- 1.8 million years). The new data suggest that the Galápagos Islands are younger than previously supposed on the basis of marine magnetic anomaly dating, but they are older than most previously dated rocks from the Galápagos.     

RopGAP4-dependent Rop GTPase rheostat control of Arabidopsis oxygen deprivation tolerance

Transient soil flooding limits cellular oxygen to roots and reduces crop yield. Plant response to oxygen deprivation involves increased expression of the alcohol dehydrogenase gene (ADH) and ethanolic fermentation. Disruption of the Arabidopsis gene that encodes Rop (RHO-like small G protein of plants) guanosine triphosphatase (GTPase) activating protein 4 (ROPGAP4), a Rop deactivator, elevates ADH expression in response to oxygen deprivation but decreases tolerance to stress. Rop-dependent production of hydrogen peroxide via a diphenylene iodonium chloride-sensitive calcium-dependent reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is necessary for induction of both ADH and RopGAP4 expression. Tolerance to oxygen deprivation requires Rop activation and RopGAP4-dependent negative feedback regulation. This Rop signal transduction rheostat balances the ability to increase ethanolic fermentation with survival.     

Lead effects on corn mitochondrial respiration

Oxidation of exogenous nicotinamide-adenine dinucleotide and succinate by corn mitochondria was measured as a function of lead chloride concentration. Lead chloride (50 to 62 micromoles per liter) stimulated oxidation of exogenous reduced nicotinamide-adenine dinucleotide by 174 to 640 percent depending on the reaction mediums, whereas lead chloride (12.5 micromoles per liter) inhibited succinate oxidation by more than 80 percent. When inorganic phosphate was included in reaction mediums the subsequent addition of lead was without effect due to the low solubility of lead phosphate. If addition of lead was followed by addition of phosphate the inhibition of succinate oxidation by lead was released, but there was no reduction in the stimulation of oxidation of reduced nicotinamide-adenine dinucleotide by lead. The effects of lead on plant growth might be accentuated under conditions of phosphate deficiency.     

Est1p as a cell cycle-regulated activator of telomere-bound telomerase

In Saccharomyces cerevisiae, the telomerase components Est2p, TLC1 RNA, Est1p, and Est3p are thought to form a complex that acts late during chromosome replication (S phase) upon recruitment by Cdc13p, a telomeric DNA binding protein. Consistent with this model, we show that Est1p, Est2p, and Cdc13p are telomere-associated at this time. However, Est2p, but not Est1p, also binds telomeres before late S phase. The cdc13-2 allele has been proposed to be defective in recruitment, yet Est1p and Est2p telomere association persists in cdc13-2 cells. These findings suggest a model in which Est1p binds telomeres late in S phase and interacts with Cdc13p to convert inactive, telomere-bound Est2p to an active form.     

鸡β防御素1基因密码子优化及其在真核细胞中的表达

 鸡β防御素1在鸡防御系统中起重要作用,为实现其在真核细胞中的表达,本研究利用RT PCR从狼山鸡法氏囊中扩增出鸡β防御素1成熟肽基因,同时参照酵母密码子的偏好性,设计合成Gal 1成熟肽片段新基因,并在其3′端添加6×His序列以检测鸡β防御素1的表达情况,分别构建分泌型表达载体pPIC9K-Gal-1和pPIC9K-Gal-1-a-His,线性化后电转化导入毕赤酵母菌株GS115,G418抗性筛选高拷贝转化子,阳性克隆用甲醇诱导,Tricine SDS-PAGE分析和Western blotting鉴定表达上清液。结果表明,从狼山鸡法氏囊中扩增出鸡β防御素1成熟肽基因,其序列与GenBank登录号AF033335的序列同源性为100%;Gal-1和Gal-1-a-His基因均成功整合到毕赤酵母基因组中,重组酵母蛋白Gal-1-His获得了成功表达。本研究为后续鸡β防御素1的高效表达和生物学活性研究奠定了基础。     

Noxa, a BH3-only member of the Bcl-2 family and candidate mediator of p53-induced apoptosis

A critical function of tumor suppressor p53 is the induction of apoptosis in cells exposed to noxious stresses. We report a previously unidentified pro-apoptotic gene, Noxa. Expression of Noxa induction in primary mouse cells exposed to x-ray irradiation was dependent on p53. Noxa encodes a Bcl-2 homology 3 (BH3)-only member of the Bcl-2 family of proteins; this member contains the BH3 region but not other BH domains. When ectopically expressed, Noxa underwent BH3 motif-dependent localization to mitochondria and interacted with anti-apoptotic Bcl-2 family members, resulting in the activation of caspase-9. We also demonstrate that blocking the endogenous Noxa induction results in the suppression of apoptosis. Noxa may thus represent a mediator of p53-dependent apoptosis.     

Origin of espanola island and the age of terrestrial life on the galapagos islands

Geological studies of Espa?ola (Hood) Island, Galápagos, Ecuador, indicate that the island had a subaerial rather than a submarine origin. Because the younger lava flows are dated at 3 million years, Espa?ola has apparently existed as an island for at least that long. Thus terrestrial life may have existed or arrived on the Galápagos Islands at least 3 million years ago, more than twice as long as had been assumed.     

降解膜覆盖对滴灌玉米土壤水温变化及其生长的影响

针对聚乙烯地膜覆盖产生的农田残膜污染问题,探明新疆滴灌条件下可降解地膜覆盖在玉米上的应用效果。通过设置不同降解膜(M1:诱导期为100 d,黑色氧化生物双降解膜;M2:诱导期为80 d,白色氧化生物双降解膜;M3:诱导期为80 d,黑色完全生物降解膜;M4:诱导期为100 d,白色完全生物降解膜)和普通地膜(PE)共5种处理,研究降解膜覆盖对滴灌玉米土壤水温变化及生长的影响。结果表明:灌浆期前,各处理间土壤含水率无显著差异;灌浆期后,M2和M3处理21～40 cm平均土壤含水率较PE膜处理显著降低2.76%和2.89%,M1和M4处理与PE膜处理无显著差异。灌浆期至成熟期,4种降解膜处理各土层土壤平均温度与PE膜处理无显著差异。玉米苗期5～25 cm土层土壤温度日变化均呈现低—高—低变化趋势。相较于PE膜处理,生育前期降解膜处理对玉米株高、茎粗、叶面积指数和干物质积累量不产生显著影响,成熟期M1、M2、M3和M4处理的玉米株高分别减小3.09%、2.23%、2.50%和1.44%,干物质积累量分别减小0.87%、6.67%、2.72%和2.29%。对照于PE膜处理,M1、M2、M3和M4处理的产量分别降低0.43%、19.18%、5.74%和5.40%,水分利用效率分别降低1.09%、17.06%、5.42%和4.62%,其中M1处理与PE膜处理差异不显著。综上,诱导期为100 d的黑色氧化生物双降解地膜(M1)应用效果较好,可考虑在干旱区的生产实践中推广使用。     

Abraxas and RAP80 form a BRCA1 protein complex required for the DNA damage response

The BRCT repeats of the breast and ovarian cancer predisposition protein BRCA1 are essential for tumor suppression. Phosphopeptide affinity proteomic analysis identified a protein, Abraxas, that directly binds the BRCA1 BRCT repeats through a phospho-Ser-X-X-Phe motif. Abraxas binds BRCA1 to the mutual exclusion of BACH1 (BRCA1-associated C-terminal helicase) and CtIP (CtBP-interacting protein), forming a third type of BRCA1 complex. Abraxas recruits the ubiquitin-interacting motif (UIM)-containing protein RAP80 to BRCA1. Both Abraxas and RAP80 were required for DNA damage resistance, G(2)-M checkpoint control, and DNA repair. RAP80 was required for optimal accumulation of BRCA1 on damaged DNA (foci) in response to ionizing radiation, and the UIM domains alone were capable of foci formation. The RAP80-Abraxas complex may help recruit BRCA1 to DNA damage sites in part through recognition of ubiquitinated proteins.     

Gravitational Evidence for a Low-Density Mass beneath the Galapagos Islands

A residual negative free-air and Bouguer anomaly of at least 80 milligals, superimposed on a broader high, occurs over the Galápagos Islands The axis of the anomaly trends roughly east and plunges eastward. Thus, a low-density mass in the crust or upper mantle must underlie the archipelago. This anomaly may be caused by thermal expansion over a crust-mantle " hot spot".     

Structure of an HIF-1alpha -pVHL complex: hydroxyproline recognition in signaling

The ubiquitination of the hypoxia-inducible factor (HIF) by the von Hippel-Lindau tumor suppressor (pVHL) plays a central role in the cellular response to changes in oxygen availability. pVHL binds to HIF only when a conserved proline in HIF is hydroxylated, a modification that is oxygen-dependent. The 1.85 angstrom structure of a 20-residue HIF-1alpha peptide-pVHL-ElonginB-ElonginC complex shows that HIF-1alpha binds to pVHL in an extended beta strand-like conformation. The hydroxyproline inserts into a gap in the pVHL hydrophobic core, at a site that is a hotspot for tumorigenic mutations, with its 4-hydroxyl group recognized by buried serine and histidine residues. Although the beta sheet-like interactions contribute to the stability of the complex, the hydroxyproline contacts are central to the strict specificity characteristic of signaling.