共查询到20条相似文献,搜索用时 31 毫秒
1.
Akitami Ichihara Koichi Moriyasu Sadao Sakamura 《Bioscience, biotechnology, and biochemistry》2013,77(12):2421-2422
Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice. 相似文献
2.
第三节祖国在防治疾病上的伟大成就这节课是在学生已掌握了传染病的基本知識的基础上来进行講授的,首先在教材里提出以血吸虫病、天花、瘧疾、黑热病、痳疯等传染病說明了新旧社会的对比;同时也说明了社会主义社会制度的优越性。我們的党和政府对于人民健康的关怀是无微不至的,并且对于各种疾病的积极防治工作加强了党的领导,及时提出了一系列的方針、政策和措施;建立了专业防治机构,培养了专业干部;結合生产发动了广大羣众来参加防治。因此在防治各种传染病的工作中取得了很大的成績。 相似文献
3.
第五节大脑皮层的机能——高级神經活动本节是本章也是本書的高峯,是把过去学习过有关反射作用的知識进行总結和提高,使学生能从理論上理解神经对人的意义——保持內部各器官的协調,同外界环境的统一。 相似文献
4.
Hall(1977)首次在新西兰的土壤中发现GlomusinjtequensHall。Ames和Schneider(979)在美国的加利福尼亚再次发现了这个种。他们认为该种与无梗囊霉(Acauloryora)有相似之处,抱子都是从泡囊发育而成,但无梗囊霉的抱于是在产抱囊的侧面形成,而该种的抱子则是在产抱囊柄的内部发育而成的。为此,Ames和Schneider(197)为这个种建立起一个新属——内养囊霉属(Entrophospora),把这个种改名为稀有内养囊霉Entrophoworam斤equens(HallAmesetSchnelder。SChellGk和Spain(1984)报道了这个属的另一个种哥伦比亚内养囊霉(Entro… 相似文献
5.
Jan M. Anderson 《Photosynthesis research》1991,30(1):1-5
Obituary
Robert (Robin) Hill (1899–1991) 相似文献6.
TheZhoukoudian(Choukoutien)Site(英汉对照)TheZhoukoudianSite,famous“home”ofPekingMan,liesapproximately50kilometressouthwestofthePe... 相似文献
7.
Rengaswami Chandrasekaran Andrea Giacometti Struther Arnott 《Journal of biomolecular structure & dynamics》2013,31(6):1011-1022
Abstract The molecular structure of poly (dT)·poly (dA)·poly (dT) has been determined and refined using the continuous x-ray intensity data on layer lines in the diffraction pattern obtained from an oriented fiber of the DNA. The final R-value for the preferred structure is 0.29 significantly lower than that for plausible alternatives. The molecule forms a 12-fold right- handed triple-helix of pitch 38.4 Å and each base triplet is stabilized by a set of four Crick-Watson-Hoogsteen hydrogen bonds. The deoxyribose rings in all the three strands have C2′-endo conformations. The grooveless cylindrical shape of the triple-helix is consistent with the lack of lateral organization in the fiber. 相似文献
8.
X-ray diffraction analyses of fibers of polydeoxyadenylic acid · polydeoxythymidylic acid show that this molecule exists as a 10-fold double-helix with axial rise per nucleotide . The structure is very similar to B-DNA () in having C3-exo furanose rings and base-pairs positioned centrally on the helix axis, but distinctive enough to have two packing modes, neither of which has been observed for B-DNA. Although the triple-stranded poly(dT) · poly(dA) · poly(dT) also has a large value of h(3.26 Å), each of the chains is a 12-fold helix of the A-genus with C3-endo furanose rings and bases displaced several Angstrom units from the helix axis. 相似文献
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10.
(S)-(?)-Vertinolide 1 was synthesized via the tetronic acid derivative 6 from (S)-(?)-tetrahydro-2-methyl-5-oxo-2-furancarboxylic acid 3. (±)-Vertinolide was also synthesized from (±)-3. 相似文献
11.
3 临床治疗 3.1 临床肿瘤学拨款临床肿瘤学规划提供的拨款,支持研究治疗人类癌症中抗癌剂的应用及其效果的评估。它包括四个特殊领域:化疗药物的毒性和效果,单独激素治疗或同其它治疗方式相结合的临床研究;用动物模型和细胞系统发展治疗研究;对可能干扰抗癌药物活性,与癌有关的失调进行研究;进行癌症临床试验新方法的研究。该规划拨款还对癌症治疗时引起癌症患者承担的潜伏生命威胁处境给予支持。出血控制时的血小板转输,白血球输送, 相似文献
12.
Peter E. Prevelige Gerald D. Fasman 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1983,739(1):85-96
Core histones, (H2A,H2B,H3,H4)2, were reconstituted with the synthethic polynucleotides poly(dA-dT)·poly(dA-dT) and poly(dG-dC)·poly(dG-dC) to yield synthetic chromatins containing 200 basepairs per octamer. These synthetic chromatins displayed a 36% decrease in the circular dichroism (CD) peak ellipticity from the value of the polynucleotide free in solution; the poly(dA-dT)·poly(dA-dT)/chromatin showed an increase in the complexity of the thermal denaturation profile compared to that of the polynucleotide. Both the temperature of maximum for each transition (Tm) and the relative amount of poly(dA-dT)·poly(dA-dT) in the synthetic chromatin melting in each of the four thermal transitions is a function of the ionic strength over the 0–5 mM sodium phosphate range (0.25 mM EDTA, pH 7.0); a shift of material toward higher melting transitions was observed with increasing ionic strength. The CD peak ellipticity value for both synthetic chromatins was ionic strength-independent over the 0–5 mM sodium phosphate range. These results are in contrast to those observed with stripped chicken erythrocyte chromatin (Fulmer, A. and Fasman, G.D. (1979) Biopolymers 18, 2875–2891), where an ionic strength dependence was found. Differences in the CD spectra between poly(dA-dT)·poly(dA-dT)/chromatin, poly(dG-dC)·poly(dG-dC)/chromatin and stripped chicken erythrocyte chromatin suggest subtle differences in assembly. Finally, the temperature dependence of the CD spectra of poly(dA-dT)·poly(dA-dT)-containing synthetic chromatin, which is similar to that for the polynucleotide, suggests the core histone bound polynucleotide has a large degree of conformational flexibility allowing it to undergo the premelt transition. 相似文献
13.
D. Hennig E. B. Starikov J. F. R. Archilla F. Palmero 《Journal of biological physics》2004,30(3):227-238
We investigate the charge transport in synthetic DNA polymers built up from single type of base pairs. In the context of a polaronlike model, for which an electronic tight-binding system and bond vibrations of the double helix are coupled, we present estimates for the electron-vibration coupling strengths utilizing a quantum-chemical procedure. Subsequent studies concerning the mobility of polaron solutions, representing the state of a localized charge in unison with its associated helix deformation, show that the system for poly(dG)–poly(dC) and poly(dA)–poly(dT) DNA polymers, respectively possess quantitatively distinct transport properties. While the former supports unidirectionally moving electron breathers attributed to highly efficient long-range conductivity, the breather mobility in the latter case is comparatively restrained, inhibiting charge transport. Our results are in agreement with recent experimental results demonstrating that poly(dG)–poly(dC) DNA molecules acts as a semiconducting nanowire and exhibit better conductance than poly(dA)–poly(dT) ones. 相似文献
14.
Peter N Alexandrov Prerna Dua James M Hill Surjyadipta Bhattacharjee Yuhai Zhao Walter J Lukiw 《International Journal of Biochemistry and Molecular Biology》2012,3(4):365-373
Human cerebrospinal fluid (CSF), produced by the choroid plexus and secreted into the brain ventricles and subarachnoid space, plays critical roles in intra-cerebral transport and the biophysical and immune protection of the brain. CSF composition provides valuable insight into soluble pathogenic bio-markers that may be diagnostic for brain disease. In these experiments we analyzed amyloid beta (Aβ) peptide and micro RNA (miRNA) abundance in CSF and in short post-mortem interval (PMI <2.1 hr) brain tissue-derived extracellular fluid (ECF) from Alzheimer’s disease (AD) and age-matched control neocortex. There was a trend for decreased abundance of Aβ42 in the CSF and ECF in AD but it did not reach statistical significance (mean age ~72 yr; N=12; p~0.06, ANOVA). The most abundant nucleic acids in AD CSF and ECF were miRNAs, and their speciation and inducibility were studied further. Fluorescent miRNA-array-based analysis indicated significant increases in miRNA-9, miRNA-125b, miRNA-146a, miRNA-155 in AD CSF and ECF (N=12; p<0.01, ANOVA). Primary human neuronal-glial (HNG) cell co-cultures stressed with AD-derived ECF also displayed an up-regulation of these miRNAs, an effect that was quenched using the anti-NF-кB agents caffeic acid phenethyl ester (CAPE) or 1-fluoro-2-[2-(4-methoxy-phenyl)-ethenyl]-benzene (CAY10512). Increases in miRNAs were confirmed independently using a highly sensitive LED-Northern dot-blot assay. Several of these NF-кB-sensitive miRNAs are known to be up-regulated in AD brain, and associate with the progressive spreading of inflammatory neurodegeneration. The results indicate that miRNA-9, miRNA-125b, miRNA-146a and miRNA-155 are CSF- and ECF-abundant, NF-кB-sensitive pro-inflammatory miRNAs, and their enrichment in circulating CSF and ECF suggest that they may be involved in the modulation or proliferation of miRNA-triggered pathogenic signaling throughout the brain and central nervous system (CNS). 相似文献
15.
自七十年代发现了紫杉醇(taxol)独特的抗癌机制一促进微管蛋白聚合、抑制微管蛋白解聚后,紫杉醇及其类似物紫杉烷类二该化合物的资源调查和化学研究倍受重视。紫杉醇主要存在于红豆杉科的大多数植物中,红豆杉科(Taxaceae)红豆杉属(TaxuS)植物全球大约有11种,我国有4种和1个变种。我们从采自湖北神农架的红豆杉(Tchinens周树皮中分离得到8个结晶性物质,本文报道其中已鉴定的3个成分,即taxinineJ(l),ldiydroxybaccatinl(2)和taxol(3)。据文献报道,已经从红豆杉分离得到二十多种紫杉烷类化合物l'l,而我们分离得到的1和2… 相似文献
16.
Specific salt effects were studied on the quenching reaction of excited [Ru(N-N)3]2+ (N-N=2,2′-bipyridine (bpy), 1,10-phenanthrorine (phen)) and [Cr(bpy)3]3+ by [Cr(ox)3]3− (ox=oxalate ion) and [Cr(mal)3]3− (mal=malonate ion) in aqueous solutions as a function of alkali metal ions which were added for adjustment of ionic strength. The value of kq, quenching rate constants, and k1, energy transfer rate constant in encounter complex, is changed by the cations as the order of Li+ > Na+ > K+ ≈ Rb+ ? Cs+, although diffusion rate constants are not changed by the co-existing cations. Among the quenching reactions investigated in this work, a ratio of k1 values in the aqueous solutions whose ionic strength was adjusted with LiCl and KCl, k1LiCl/k1KCl, is larger for quenching systems of closely approached donor-acceptor pair than loosely bounded pair. These results indicate that co-existing alkali cation tunes the distance between donor and acceptor in encounter complex where energy transfer occurs. 相似文献
17.
Mono(maleonitriledithiolene)sulfidomolybdenum(IV) complex, [MoS(S(4) )(mnt)](2-) (2; mnt=maleonitriledithiolene) was synthesized by the substitution reaction of a tetrasulfido ligand of the known [MoS(S(4) )(2) ](2-) (1) upon reaction with one or even excess equivalent of Na(2) (mnt) in aqueous MeCN solution in air. Surprisingly, 2 undergoes dimerization on treatment with alkyl halide such as MeI and PhCH(2) Br to form bis(μ-sulfido)dimolybdenum(V) species, [{MoS(mnt)}(2) (μ-S)(2) ](2-) (3). These complexes have been characterized by IR, UV/VIS spectroscopy, cyclic voltammetry, elemental analysis, and by X-ray crystal-structure analysis. Differences in the relative stability and electrochemical behavior of 1, 2, and 3 have been correlated with theoretical calculations at DFT level. 相似文献
18.
A truncated form of the Agouti‐related protein (AgRP), a member of the cystine‐knot family, has shown promise as a scaffold for engineering novel peptides with new molecular recognition properties. In this study, we replaced a constrained six amino acid loop in AgRP with a nine amino acid loop containing an Arg–Gly–Asp integrin recognition motif, and randomized the neighboring residues to create a library of ~20 million AgRP variants. We displayed the AgRP mutants as fusions on the surface of yeast and used high‐throughput fluorescence‐activated cell sorting (FACS) to isolate peptides that bound specifically to the platelet integrin αIIbβ3, a clinically important target for the prevention and treatment of thrombosis. These AgRP peptides had equilibrium dissociation (KD) constants for αIIbβ3 integrin ranging from 60 to 90 nM, and did not bind to αvβ3, αvβ5, or α5β1 integrins. Using an alternate library screening strategy, we identified AgRP peptides that bound to both αIIbβ3 and αvβ3 integrins with KD values ranging from 40 to 70 nM and 20 to 30 nM, respectively, and did not bind to αvβ5 or α5β1 integrins. Unique consensus sequences were identified within both series of AgRP peptides suggesting alternative molecular recognition events that dictate different integrin binding specificities. In addition, the engineered AgRP peptides prevented platelet aggregation as well as or slightly better than the FDA‐approved cyclic peptide eptifibatide. Collectively, these data demonstrate that cystine‐knot peptides can be generated with high affinity and specificity to closely‐related integrins, and provide insights into molecular interactions between small, structured peptide ligands and their receptors. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
异(虫元)亚科的研究(原尾目:古(虫元)科) 总被引:1,自引:0,他引:1
自从1977年建立异(虫元)属(Anisentomon Yin)以来,在我国又陆续记述了一些种类,并于1982年由尹文英制定原尾虫新的分类体系时,将这一类单独成立为一个亚科。近年来,我们从云南、广东、广西等地的标本中又发现了8个新种,经过整理,将国内、外已知的23种,按形态特征,拟分为4个属,现分别记述于后。新种的模式标本全部保存于中国科学院上海昆虫研究所。 相似文献
20.
栖息地选择的遗传与获得据目前研究所知,动物对栖息地的选择具有一定的遗传性和后天获得性(即可借助于早期生活经验和学习而改进)。如果把两种动物饲养在同一环境中,发现它们对栖息地的选择有所不同,那么这种差异大都是由遗传所决定的。例如:把从未在自然植被中生活过的蓝山雀和煤山雀关在同一个鸟舍中,鸟舍内放有栎树枝和松树枝,观察记录表明,煤山雀大部分时间都停栖在松树枝上,而蓝山雀则主要停栖在栎树枝上。这种不同的选择同这两种山雀在自然状态下对栖息地的不同偏爱是一致的(蓝山雀偏爱阔叶林,而煤山雀偏爱针叶林)。 相似文献