Drilling to gabbro in intact ocean crust     

Wilson DS  Teagle DA  Alt JC  Banerjee NR  Umino S  Miyashita S  Acton GD  Anma R  Barr SR  Belghoul A  Carlut J  Christie DM  Coggon RM  Cooper KM  Cordier C  Crispini L  Durand SR  Einaudi F  Galli L  Gao Y  Geldmacher J  Gilbert LA  Hayman NW  Herrero-Bervera E  Hirano N  Holter S  Ingle S  Jiang S  Kalberkamp U  Kerneklian M  Koepke J  Laverne C  Vasquez HL  Maclennan J  Morgan S  Neo N  Nichols HJ  Park SH  Reichow MK  Sakuyama T  Sano T  Sandwell R  Scheibner B  Smith-Duque CE  Swift SA  Tartarotti P  Tikku AA  Tominaga M  Veloso EA 《Science (New York, N.Y.)》2006,312(5776):1016-1020

Sampling an intact sequence of oceanic crust through lavas, dikes, and gabbros is necessary to advance the understanding of the formation and evolution of crust formed at mid-ocean ridges, but it has been an elusive goal of scientific ocean drilling for decades. Recent drilling in the eastern Pacific Ocean in Hole 1256D reached gabbro within seismic layer 2, 1157 meters into crust formed at a superfast spreading rate. The gabbros are the crystallized melt lenses that formed beneath a mid-ocean ridge. The depth at which gabbro was reached confirms predictions extrapolated from seismic experiments at modern mid-ocean ridges: Melt lenses occur at shallower depths at faster spreading rates. The gabbros intrude metamorphosed sheeted dikes and have compositions similar to the overlying lavas, precluding formation of the cumulate lower oceanic crust from melt lenses so far penetrated by Hole 1256D.  相似文献   

Identification and characterization of conjugated linolenic acid isomers by Ag+-HPLC and NMR     

Cao Y  Gao HL  Chen JN  Chen ZY  Yang L 《Journal of agricultural and food chemistry》2006,54(24):9004-9009

Interest in the biological activity of conjugated linolenic acids (CLnA) is growing. Technically, previous methods could not fully characterize and identify CLnA isomers. The present study is the first report on application of silver ion impregnated high-performance liquid chromatography (Ag+-HPLC) into separation of CLnA methyl ester (CLnAMe) mixture. Compared with the GC and reversed-phase HPLC techniques, Ag+-HPLC could resolve and separate CLnAMe isomers into three clusters of peaks namely ttt, ctt and ctc geometrical groups. Each positional isomer belonging to the same geometrical group could be further separated by Ag+-HPLC. Quantitative 13C NMR properties of CLnAMe mixture were subsequently studied. Olefinic signals in the CLnAMe mixture were assigned and used to quantify each isomer in combination with Ag+-HPLC. The present study provided a detailed analysis of a complex CLnA mixture and may have an important application in future studies dealing with synthesis, oxidative stability, and bioactivity of individual CLnA isomers.  相似文献   

育苗基质的养分供应对青花菜幼苗生长的影响   总被引：2，自引：0，他引：2  

李祥云  赵明  高峻岭  宋朝玉  朱培生 《北方园艺》2006,(3):7-9

采用正交试验法,对青花菜无土育苗基质中的最佳施肥量进行了研究.结果表明,适量增施氮肥可显著促使幼苗生长、干物质积累和对养分的平衡吸收,青花菜无土育苗的最佳施肥量每立方米为:N0.4 kg、P2O5 0.4 kg、K2O 0.1 kg.  相似文献   

Purification, characterization, and gene cloning of a chitosanase from Bacillus species strain s65     

Su C  Wang D  Yao L  Yu Z 《Journal of agricultural and food chemistry》2006,54(12):4208-4214

For the production of oligosaccharides from chitosan, a chitosanase-producing bacterium, S65, was isolated from soil. On the basis of phylogenetic analysis of the 16S rDNA gene sequence and phenotypic analysis, S65 was identified as a Bacillus sp. strain. This bacterium constitutively produced chitosanase in a culture medium without chitosan as an inducer. S65 chitosanase was homogeneously purified by DEAE Sepharose fast flow anion exchange followed by Superdex 75 size exclusion, and the molecular weight was 45 kDa according to SDS-PAGE. Enzyme analysis showed that the optimum pH and temperature of S65 were 6.0 and 65 degrees C, respectively. Catalytic activity was stable from pH 5.5-6.5 at temperatures below 40 degrees C, and the pI of chitosanase was about 6.0 as determined by a test tube method. S65 chitosanase degraded carboxymethyl cellulose (CMC) at the degree of about 5.3% relative to the value of soluble chitosan, but it cannot hydrolyze colloidal chitin and crystalline cellulose. Gene encoding was cloned and sequenced. The deduced amino acid sequence of the S65 exhibited the highest homology to those of family 8 glycanase, suggesting that the enzyme belonged to family 8.  相似文献   

Phosphatized polar lobe-forming embryos from the Precambrian of southwest China     

Chen JY  Bottjer DJ  Davidson EH  Dornbos SQ  Gao X  Yang YH  Li CW  Li G  Wang XQ  Xian DC  Wu HJ  Hwu YK  Tafforeau P 《Science (New York, N.Y.)》2006,312(5780):1644-1646

In developing embryos of some extant spiralian animals, polar lobe formation is one of the symmetry-breaking mechanisms for segregation of maternal cytoplasmic substances to certain blastomeres and not others. Polar lobe formation leads to unique early cleavage morphologies that include trilobed, J-shaped, and five-lobed structures. Fossil embryos similar to modern lobeforming embryos are recognized from the Precambrian Doushantuo Formation phosphates, Weng'an, Guizhou Province, China. These embryos are abundant and form a developmental sequence comparable to different developing stages observed in lobe-forming embryos of extant spiralians. These data imply that lobe formation is an evolutionarily ancient process of embryonic specification.  相似文献   

Characterization of imidacloprid resistance in the housefly Musca domestica (Diptera: Muscidae)     

Jing Li  Qingmin Wang  Lan Zhang  Xiwu Gao 《Pesticide biochemistry and physiology》2012,102(2):109-114

In recent years, imidacloprid was introduced to control the housefly in China and it was documented that the housefly indeed showed signs of resistance to imidacloprid somewhere but not in China. Therefore, a housefly population collected from filed (IFS) was selected continuously with imidacloprid to establish the resistant strain (IRS) and the basic characteristics were investigated in this study. After continuous selection over 21 generations, the resistance ratio increased from 9.01 to 140, and different levels of cross-resistance were developed to beta-cypermethrin, chlorpyrifos, chlorfenapyr, acetamiprid and azamethiphos in the IRS strain. The realized heritability of resistance was 0.10. The synergistic ratios for IRS pretreated with DEF, DEM and PBO were 1.68, 1.52 and 2.53, and the corresponding ones for IFS were 3.17, 1.87 and 2.67, respectively. Synergistic and biochemical assays suggested that the cytochrome P450 may play an important role in the imidacloprid resistance comparing with GSTs- and carboxylesterases-mediated detoxification in the IRS strain, and there might be additional mechanisms (e.g. reduced target-site sensitivity) contributed to imidacloprid resistance in the IRS strain.  相似文献   

Frequencies of the M918I mutation in the sodium channel of the diamondback moth in China, Thailand and Japan and its association with pyrethroid resistance     

Shoji Sonoda  Xueyan ShiDunlun Song  Youjun ZhangJianhong Li  Gang WuYong Liu  Ming LiPei Liang  David WariMasaya Matsumura  Chieka MinakuchiToshiharu Tanaka  Tadashi MiyataXiwu Gao 《Pesticide biochemistry and physiology》2012,102(2):142-145

In addition to the allele frequencies of the L1014F and T929I mutations which are involved in nerve-insensitive resistance to a pyrethroid, those of the M918I mutation were examined using field strains obtained in China, Thailand, and Japan during 2009-2011. Results show that the resistance allele frequencies at the L1014F site were 89-100%, 97-100% and 65-85%, respectively, for strains in China, Thailand, and Japan. The respective allele frequencies at the T929I site were 86-100%, 70-97% and 58-84% for Chinese, Thai, and Japanese strains. With low frequencies up to 27%, M918I was found in Japan and China, but not in Thailand. The strain homozygous for the M918I and L1014F mutations was established and its resistance level to a pyrethroid was examined. The strain lacks a portion of the sodium channel gene corresponding to the 3′ portion of exon 18a, intron 18, and the 5′ portion of exon 18b. Nevertheless, the strain showed a similar level of resistance to that which was homozygous for the T929I and L1014F mutations.  相似文献   

山东泰安地区小麦禾谷孢囊线虫幼虫孵化特性初步研究   总被引：1，自引：0，他引：1  

宋晓磊  高德良  程永  苗建强  刘峰 《植物保护》2012,38(1):95-97

为大量获得研究所需的小麦禾谷孢囊线虫2龄幼虫,在室内离体条件下研究了预处理条件、孵化温度、低温预处理时间以及田间采样时期对山东泰安地区小麦禾谷孢囊线虫幼虫孵出量的影响.结果表明:5℃低温预处理条件下,孢囊浸水处理有利于幼虫孵出;低温预处理后,孵化温度为15℃处理的2龄幼虫孵出率高于20℃处理的孵出率;低温预处理时间为8周的2龄幼虫孵出率最高;6月和8月田间采集的孢囊幼虫孵出率显著高于7月和9月,其中8月采集的孢囊幼虫孵出率最高,为最佳采集时间.  相似文献   

施用胂·锌·福美双对西洋参及其栽培土壤中砷残留量的影响     

张雪松  王亚平  苏文忠  王振丰  高微微 《植物保护》2012,38(2):143-146

选择3年生西洋参进行田间试验,设计胂·锌·福美双两个施用量以400～600倍药液均匀喷施全株,处理2年后,测定田间土壤样品及西洋参根中砷含量.西洋参根中砷含量与胂·锌·福美双的使用量有显著相关关系,与对照相比,每年施用3～4次胂·锌·福美双,砷含量增加64.52％～101.68％,但低于目前中国药典的相关规定(2mg/kg).胂·锌·福美双的施用与土壤砷含量无显著相关关系(R2 =0.1890).在相同施用量情况下,随着有机质含量的增加土壤砷含量有所增加.含砷类农药的施用有可能增加西洋参中砷的残留,应尽量减少高含量重金属杀菌剂的应用并关注有关肥料的使用.  相似文献   

小麦孢囊线虫病传播扩散途径研究初报   总被引：4，自引：0，他引：4  

汪涛  戚仁德  吴向辉  赵伟  高同春  张琍  吴慧平 《植物保护》2012,38(1):98-100

为了明确小麦孢囊线虫病的扩散传播途径,调查病区农用机械、麦田翻耕后田间及其周边流水中小麦孢囊线虫的孢囊数量.结果表明,收割机、旋耕机和播种机上土样的孢囊检出率分别为27.1％、51.6％和44.0％,麦稻轮作的病田中,浪渣的孢囊检出率为58.3％,翻耕后麦田积水、沟渠和小河流中的孢囊检出率分别为33.3％、22.7％和7.7％.说明农业机械的跨区作业和水流是小麦孢囊线虫病传播、扩散的重要途径.  相似文献