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1.
The syntheses and reactions of two epoxyketoacids (methyl (Z)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (IV) and methyl (E)-9,10-epoxy-13-oxo-(E)-11-octadecenoate (V)) are described. The synthetic method is based on the stereoselective oxidation of linoleic acid by soybean lipoxygenase to produce the corresponding 13-hydroperoxide. Reduction of the hydroperoxide with sodium borohydride followed by oxidation, esterification and epoxidation yielded the compounds IV and V with a global yield of 14% and 3%, respectively, referred to the diasteromerically pure isolated compounds. Confirmation of the structures was carried out by reduction of the ketone group with sodium borohydride and by the opening of the oxirane ring with methanolic boron trifluoride. The reduction of compounds IV and V with hydrogen mainly yielded the tetrahydrofuranoid fatty acid, methyl 10,13-epoxyoctadecanoate. This reaction may be considered a new procedure to obtain tetrahydrofuranoid fatty acids.  相似文献   

2.
A diastereo- and enantio-selective synthesis of the (E)-alkene dipeptide isostere of -Ala- -Ala from -alanine has been developed which proceeds via stereocontrolled addition of a (Z)-vinyllithium reagent followed by a [2,3]-Wittig rearrangement. The synthesis proceeds in seven steps overall from -alanine methyl ester. It is believed that this approach will provide a fairly general and convenient route to isosteres of a number of different dipeptides.  相似文献   

3.
天然免疫系统是多细胞生物抵抗各种入侵微生物的第一道防线.Notch途径介导相邻细胞之间的相互作用,调节细胞、组织、器官的分化和发育.为了进一步探索Notch信号途径在果蝇天然免疫中的功能,利用Notch途径下游基因Su(H)和E(spl)的低表达突变体果蝇,通过体外注射病原体分析了生存率、血细胞的噬菌功能和抗菌肽的表达量以及突变体的血细胞数量.结果表明,革兰氏阴性细菌和真菌感染后果蝇E(spl)突变体的生存率、噬菌能力及抗菌肽的表达量明显降低,而且幼虫期血细胞出现异常增殖;Su(H)突变体只对真菌表现出敏感性,抗菌肽的表达量降低,但是对真菌的噬菌能力正常.此结果表明,Notch途径不仅影响个体的生长发育,而且在果蝇天然免疫中也起重要的调节作用.  相似文献   

4.
Natural 2(E)-hexenal was produced in two steps from hydrolysed linseed oil, which contains the most linolenic acid among the available natural sources. In the first step 13-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid (13-HPOT) was formed from linolenic acid (100 mM) by soybean lipoxygenase-1 (Lox-1) isoenzyme with oxygen as co-substrate. The reaction resulted in 57 mM 13-HPOT with a yield of 62%. In the second step 13-HPOT (20 mM) was cleaved by green bell pepper hydroperoxide lyase resulting in 1.6 mM 2(E)-hexenal and 5.9 mM 3(Z)-hexenal (37% yield for the hexenal isomers together). Hexenals were isolated from the reaction mixture by repeated steam distillations. During distillations the 2(E)-hexenal:3(Z)-hexenal isomer ratio was changed from 0.27 to 7.86 as a consequence of heat.  相似文献   

5.
(E)-9-(1-pyrenyl)-4-hydroxynon-2-enal (FHNE), a fluorescent probe of (E)-4-hydroxynon-2-enal (HNE) is synthesised in seven steps and in 35% overall yield, starting from commercially available 1-pyrencarboxyaldehyde. When incubated with cultured HeLa cells this fluorescent probe penetrates cells and particularly concentrates in the region surrounding the nucleus. As the parent compound, HNE it is able to induce the activation of heat shock factor (HSF) and it is able to induce the binding of HSF to heat shock element (HSE).  相似文献   

6.
The presence of group I intron-like elements within the U7 region of the mtDNA large ribosomal subunit RNA gene (rnl) was investigated in strains of Ophiostoma novo-ulmi subsp. americana from Canada, Europe and Eurasia, and in selected strains of O. ips, O. minus, O. piceae, O. ulmi, and O. himal-ulmi. This insertion is of interest as it has been linked previously to the generation of plasmid-like mtDNA elements in diseased strains of O. novo-ulmi. Among 197 O. novo-ulmi subsp. americana strains tested, 61 contained a 1.6 kb insertion within the rnl-U7 region and DNA sequence analysis suggests the presence of a group I intron (IA1 type) that encodes a potential double motif LAGLIDADG homing endonuclease-like gene (HEG). Phylogenetic analysis of rnl-U7 intron encoded HEG-like elements supports the view that double motif HEGs originated from a duplication event of a single-motif HEG followed by a fusion event that combined the two copies into one open reading frame (ORF). The data also show that rnl-U7 intron encoded ORFs belong to a clade that includes ORFs inserted into different types of group I introns, e.g. IB, ID, IC3, IA1, present within a variety of different mtDNA genes, such as the small ribosomal subunit RNA gene (rns), apo-cytochrome b gene (cob), NADH dehydrogenase subunit 5 (nad5), cytochrome oxidase subunit 1 gene (coxI), and ATPase subunit 9 gene (atp9).

We also compared the occurrence of the rnl-U7 intron in our collection of 227 strains with the presence of the rnl-U11 group I intron and concluded that the U7 intron appears to be an optional element and the U11 intron is probably essential among the strains tested.  相似文献   


7.
8.
Making a medical diagnosis consists of correlating knownpatterns of disease with the various classes of clinical data elicited from the history, physical examination, and batteries of tests relative to the diagnostic dynamics symbolized by atree branching into the various possible diagnostic decisions. In this paper a relational mathematical model of the reasoning aspects of the conventional medical diagnostic process is suggested as a way of extracting a general, formal concept of medical diagnosis. Computer implementation of the model is discussed briefly.  相似文献   

9.
Individual plants from the BC1F6 and BC1F8 backcross progenies of barley-wheat [H. marinum subsp. gussoneanum Hudson (=H. geniculatum All.) (2n = 28) × T. aestivum L. (2n = 42)] and the BC1F6 progeny of their amphiploids were used to obtain alloplasmic euploid (2n = 42) lines L-28, L-29, and L-49 and alloplasmic telocentric addition (2n = 42 + 2t) lines L-37, L-38, and L-50. The lines were examined by genomic in situ hybridization (GISH), microsatellite analysis, chromosome C-banding, and PCR analysis of the mitochondrial 18S/5S repeat. Lines L-29 and L-49 were characterized by substitution of wild barley chromosome 7H1 for common wheat chromosome 7D. In line L-49, common wheat chromosomes 1B, 5D, and 7D were substituted with homeologous barley chromosomes. Lines L-37, L-38, and L-50 each contained a pair of telocentric chromosomes, which corresponded to barley chromosome arm 7H1L. All lines displayed heteroplasmy for the mitochondrial 18S/5S locus; i.e., both barley and wheat sequences were found. Original Russian Text ? N.V. Trubacheeva, E.D. Badaeva, I.G. Adonina, L.I. Belova, E.P. Devyatkina, L.A. Pershina, 2008, published in Genetika, 2008, Vol. 44, No. 1, pp. 81–89.  相似文献   

10.
ThechiL gene product is involved in the light-independent synthesis of chlorophyll in photosynthetic bacteria, green algae and non-flowering plants. The chloroplast genome ofChlorella vulgaris strain C-27 contains the first example of a splitchiL gene, which is interrupted by a 951 bp group I intron in the coding region. In vitro synthesized pre-mRNA containing the entire intron and parts of the flanking exon sequences is able to efficiently self-splice in vitro in the presence of a divalent and a monovalent cation and GTP, to yield the ligated exons and other splicing intermediates characteristic of self-splicing group I introns. The 5 and 3 splice sites were confirmed by cDNA sequencing and the products of the splicing reaction were characterized by primer extension analysis. The absence of a significant ORF in the long P9 region (522 nt), separating the catalytic core from the 3 splice site, makes this intron different from the other known examples of group I introns. Guanosine-mediated attack at the 3 splice site and the presence of G-exchange reaction sites internal to the intron are some other properties demonstrated for the first time by an intron of a protein-coding plastid gene.  相似文献   

11.
I studied a group of woolly monkeys (Lagothrix lagotricha)for 1800 hr from early 1985 until September 1987 near the lower Apaporis river of the Vaupés Department in the eastern Colombian Amazon. The group had an activity budget of 29.9% rest, 38.8% move, 25.8% forage, and 5.5% other activities during 720 hr of observations evenly spaced throughout this year. The only significant change in these activities during the study period was social activity, which increased as a function of increased food supply. Average diurnal activities of resting and moving are negatively correlated, and each activity show significant changes during the day, while foraging show no significant change. The activity budgets of the adult males and females are not significantly different, but the activities of the juveniles and infants showed much more social activity than the adults. High moving scores may be correlated with the comparative infertility of the soils of the Caparú forest, which require increased effort to maintain the energy levels necessary for maintenance and reproduction in Lagothrix.  相似文献   

12.
13.
何雪李  陆施毅  黄中豪  李友邦 《生态学报》2021,41(21):8664-8672
为了解白头叶猴(Trachypithecus leucocephalus)的栖息地利用规律及其影响因素,2016年2月至2017年1月,采用瞬时扫描取样法对广西崇左白头叶猴国家级自然保护区一群白头叶猴的栖息地利用进行了研究。结果表明,白头叶猴对山体不同部位的利用存在显著性差异(χ2 =39.467,df=3,P<0.001),其中,对崖壁(56.75±9.55)%的利用比例最大,其次是对山坡(39.42±10.93)%和山顶(2.98±2.54)%的利用,而对山脚(0.84±1.47)%的利用频率最低。白头叶猴对不同微生境类型的利用存在差异(χ2=27.709,df=3,P<0.001),其中对乔木(49.37±12.31)%的利用比例最大,其次是裸岩(24.05±13.61)%,随后依次为藤本(15.48±8.01)%和灌木(10.87±5.45)%。白头叶猴主要在山坡上觅食,利用崖壁移动、休息,进行社会活动;主要利用裸岩进行社会活动,觅食、移动、休息主要发生在乔木上。从整体来看,白头叶猴在雨季对乔木的利用频率显著大于旱季(Z=-2.680,n=12,P=0.007);雨季在山坡觅食频率显著大于旱季(Z=-2.517,n=12,P=0.012),而在崖壁觅食频率刚好相反(Z=-2.842,n=12,P=0.004);白头叶猴雨季在乔木休息的频率显著大于旱季(Z=-2.355,n=12,P=0.019)。白头叶猴对栖息地的利用受到温度的影响。白头叶猴对乔木的总体利用频率随着平均温度的升高而增加(r=0.664,n=12,P=0.018);觅食时,对崖壁、裸岩的利用频率均与平均温度成负相关关系(崖壁:r=-0.685,n=12,P=0.014;裸岩:r=-0.600,n=12,P=0.039);休息时,对乔木的利用频率与平均温度呈正相关关系(r=0.650,n=12,P=0.022)。不同季节,白头叶猴对栖息地的利用方式不同。白头叶猴的栖息地利用模式可能是在觅食利益和捕食风险之间作出的权衡,并受到环境温度的影响。  相似文献   

14.
It is shown that gravid Pieris brassicae L. preferentially select as hosts, individuals of Brassica oleracea L. subsp. oleracea with a strongly positive reaction to the Guignard picrate test. It is suggested that allyl nitrile is a specific attractant for P. brassicae. The larvae are shown to be non-selective in their choice of food plant, the only selection taking place at egg-laying. It is suggested that the loss of high picrate score plants during the vegetative, preflowering stage is due to this differential selection.
Zusammenfassung Eiablagebereite Weibchen von Pieris brassicae L. ziehen als Wirte Pflanzen von Brassica oleracea L. mit einer starken Reaktion auf den Guignard Picrat-Test vor. Es wird vermutet, dass Allylnitril spezifisch attraktiv für P. brassicae ist. Die Raupen sind nicht selektiv bei der Wahl der Wirtspflanze, also erfolgt die einzige Auswahl bei der Eiablage. Es wird vermutet, dass das während des vegetativen Wachstums vor der Blüte festzustellende Verschwinden von Pflanzen mit starker Picratreaktion auf dieser unterscheidenden Selektion beruht.
  相似文献   

15.
由于对模式标本考证有误,狭舌橐吾(Ligularia angustiligulata C.C.Chang)长期以来被处理为沼生橐吾[L.lamarum(Diels)C.C.Chang]的异名。经我们考证,狭舌橐吾的主模式应为藏于PE的蔡希陶58004号标本(为唯一有狭舌橐吾的作者张肇骞先生所写定名签的标本),LBG藏有1份同号模式标本,它们与狭舌橐吾的原白完全吻合,而藏于KUN(2份)和SZ(1份)的同号标本与狭舌橐吾的原白在一些重要性状上相冲突,均非狭舌橐吾的模式标本;进而发现狭舌橐吾与叶状鞘橐吾(L.phyllocoleaHand.-Mazz.)在形态上没有本质区别,故应处理为后者的异名,而藏于KUN和SZ的3份标本均属于沼生橐吾。同时还指出长柄橐吾(L.longipes C.C.Chang)的名实有待进一步研究,其模式与叶状鞘橐吾有较大区别,似不宜将其处理为叶状鞘橐吾的异名。  相似文献   

16.
17.
The chloroperoxidase (CPO)-catalyzed oxidation of the methyl (2E)-2,4-pentadienoate gives the terminal double bond epoxide (25%) and a cyclodimerization compound (63%) as the major products.  相似文献   

18.
The Corsican Nuthatch Sitta whiteheadi is a bird endemic to Corsica Island and has a very small population. Its habitat, Corsican pine Pinus nigra laricio forest, is currently restricted to less than 16,000 ha and is threatened by forest fires. In this article, we aim (1) to evaluate the effects of a large wildfire on a Nuthatch population, and (2) to identify the habitat features that influence the presence/absence of the Nuthatch after fire, so as to promote appropriate forestry practices after fire. The study has been conducted on a study plot of 300 ha which is part of a larger area severely burnt in August 2003. Habitat characteristics have been investigated on 39 plots of 1,225 m2 occupied by the bird, and 22 randomly chosen plots without the Nuthatch. We observed a decrease of 37.5% in Nuthatch abundance the first spring after the fire, but the impact showed great local variation as a function of fire severity. Logistic modelling showed that the presence of Nuthatch mainly depended on the degree of crown alteration: the Nuthatch tended to be present when at least one pine had less than 2.5 m of crown burned. We have no evidence of any direct fire-induced mortality, but several effects of fire can explain this population decrease, namely, the reduction of canopy volume, the decrease of the amount of pine seeds, and the reduction of nest-site availability. These results permit us to propose a simple criterion that can help in choosing the plots to be cut where salvage logging is necessary.  相似文献   

19.
On the basis of proportionality between flow and its conjugated force a mathematical model for volume, current and osmotic flows was designed and a method for the experimental measurement of flows, the transbarrier (trans-segmental) potential and the rate of flow was devised. The results obtained experimentally as well as using the mathematical model indicate that the plant root is differentiated not only according to localization, but also according to the conductivity, permeability and selectivity of these tissues.  相似文献   

20.
Short- and long-term consequences of natural selection, operating in accordance with the classical (non-interaction) model, are reviewed. This review provides the basis for comparisons of the optimum results of the classical model with the results from interaction models. Then as a first step, the simplest interaction modeling system (Model I) is developed subject to the following conditions: (i) The natural selection model is constructed so that it is compatible with the one that already exists for artificial selection theory. This condition ensures that an overall theory is formulated which embraces both natural and artificial selection with a single modeling system and a common notation. (ii) The interaction theory is developed so that it is an extension of the classical theory. This condition ensures that the generalized theory includes the classical results as a special case when interaction is absent.The short- and long-term consequences of selection operating with Model I are determined to be less than optimal when compared with the classical results. Future papers in this series will consider how the interaction model can be modified in order to produce results which tend toward optimality.  相似文献   

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