Another phocine distemper outbreak in Europe     

Jensen T  van de Bildt M  Dietz HH  Andersen TH  Hammer AS  Kuiken T  Osterhaus A 《Science (New York, N.Y.)》2002,297(5579):209

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Embryonic stem cells. Willingness to donate frozen embryos for stem cell research     

Lyerly AD  Faden RR 《Science (New York, N.Y.)》2007,317(5834):46-47

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The class of 2005. Germany: deciphering cellular processes     

Forde A 《Science (New York, N.Y.)》2005,310(5747):519-520

Biochemist Anne Spang will soon take up her first tenured faculty position--a professorship--at the Biozentrum in Basel, Switzerland. Her research career has taken her to four countries, where she has investigated fundamental cell biological questions.  相似文献   

Critical roles for Rac1 and Rac2 GTPases in B cell development and signaling     

Walmsley MJ  Ooi SK  Reynolds LF  Smith SH  Ruf S  Mathiot A  Vanes L  Williams DA  Cancro MP  Tybulewicz VL 《Science (New York, N.Y.)》2003,302(5644):459-462

The Rac1 guanosine triphosphatase (GTPase) has been implicated in multiple cellular functions, including actin dynamics, proliferation, apoptosis, adhesion, and migration resulting from signaling by multiple receptors, including the B cell antigen receptor (BCR). We used conditional gene targeting to generate mice with specific Rac1 deficiency in the B cell lineage. In the absence of both Rac1 and the highly related Rac2, B cell development was almost completely blocked. Both GTPases were required to transduce BCR signals leading to proliferation, survival and up-regulation of BAFF-R, a receptor for BAFF, a key survival molecule required for B cell development and maintenance.  相似文献   

The Air noncoding RNA epigenetically silences transcription by targeting G9a to chromatin   总被引：1，自引：0，他引：1  

Nagano T  Mitchell JA  Sanz LA  Pauler FM  Ferguson-Smith AC  Feil R  Fraser P 《Science (New York, N.Y.)》2008,322(5908):1717-1720

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Comment on "Mixed-layer deepening during Heinrich events: a multi-planktonic foraminiferal delta18O approach"     

Hillaire-Marcel C  de Vernal A 《Science (New York, N.Y.)》2008,320(5880):1161; author reply 1161

Rashid and Boyle (Reports, 19 October 2007, p. 439) analyzed oxygen isotopes in planktonic foraminera from marine sediments and concluded that Heinrich events (massive iceberg discharges into the North Atlantic Ocean) caused upper water masses to deepen. We question the robustness of this interpretation and argue that a strongly stratified mixed layer characterized by dense sea-ice cover and production of oxygen-18-depleted brines likely prevailed during such events.  相似文献   

Retraction     

Davis ST  Benson BG  Bramson HN  Chapman DE  Dickerson SH  Dold KM  Eberwein DJ  Edelstein M  Frye SV  Gampe RT  Grifffen RJ  Harris PA  Hassell AM  Holmes WD  Hunter RN  Knick VB  Lackey K  Lovejoy B  Luzzio MJ  Murray D  Parker P  Rocque WJ  Shewchuk-Chapman L  Veal JM  Walker DH  Kuyper LF 《Science (New York, N.Y.)》2002,298(5602):2327

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Robust crossover assurance and regulated interhomolog access maintain meiotic crossover number     

Rosu S  Libuda DE  Villeneuve AM 《Science (New York, N.Y.)》2011,334(6060):1286-1289

Most organisms rely on interhomolog crossovers (COs) to ensure proper meiotic chromosome segregation but make few COs per chromosome pair. By monitoring repair events at a defined double-strand break (DSB) site during Caenorhabditis elegans meiosis, we reveal mechanisms that ensure formation of the obligate CO while limiting CO number. We find that CO is the preferred DSB repair outcome in the absence of inhibitory effects of other (nascent) recombination events. Thus, a single DSB per chromosome pair is largely sufficient to ensure CO formation. Further, we show that access to the homolog as a repair template is regulated, shutting down simultaneously for both CO and noncrossover (NCO) pathways. We propose that regulation of interhomolog access limits CO number and contributes to CO interference.  相似文献   

Formation of Maillard reaction products during heat treatment of carrots     

Wellner A  Huettl C  Henle T 《Journal of agricultural and food chemistry》2011,59(14):7992-7998

As indicators of the early stage of the Maillard reaction in carrots, N-(furoylmethyl) amino acids (FMAAs) formed during acid hydrolysis of the corresponding Amadori products were analyzed using RP-HPLC with UV detection. N(ε)-FM-Lys (furosine), FM-Gly, FM-Ala, FM-Val, FM-Ile, FM-Leu, and FM-GABA were identified using synthesized standard material by means of mass spectrometry. Furthermore, N(ε)-carboxymethyllysine (CML) and pyrraline were analyzed as indicators for advanced stages of glycation. For commercial samples with high water content, the formation of Amadori compounds predominates, whereas the advanced stage of Maillard reaction plays only a minor part. Carrot juices, baby food, and tinned carrots showed quite low rates of amino acid modification up to 5%. For dehydrated carrots, significantly higher values for Amadori products were measured, corresponding to a lysine derivatization of up to 58% and nearly 100% derivatization of GABA. Drying experiments revealed great differences in reactivity between the amino acids studied. Whereas furosine reached constant values quite quickly, some FMAAs showed a continuous increase with heating time, indicating that selected FMAAs can be used as a hallmark for the early Maillard reaction to control processing conditions.  相似文献   

Chemical characterization of Klason lignin preparations from plant-based foods     

Bunzel M  Schüssler A  Tchetseubu Saha G 《Journal of agricultural and food chemistry》2011,59(23):12506-12513

To analyze the accuracy of the Klason lignin method as applied for the determination of lignin contents in plant based-food products, Klason lignin preparations from curly kale, pears, whole wheat grains, and corn bran were chemically characterized. Characterization included routine ash and protein determinations and the extraction of fat/waxes as well as cutin/suberin depolymerization and extraction of the liberated monomers. Fat/wax and cutin/suberin amounts in the Klason lignin preparations were determined gravimetrically, and their compositions were analyzed by using GC-MS. Typical fat, wax, and cutin (and suberin) constituents such as saturated and unsaturated fatty acids, hydroxy and/or epoxy fatty acids, and phenolic acids were identified in all samples, whereas the detection of long-chain hydrocarbons, alcohols, and ketones, sterols, stanols, and dioic acids was dependent on the sample analyzed. Estimation of the contribution of non-lignin compounds to the Klason lignin contents reduced the noncorrected Klason lignin contents of the insoluble fibers from 28.7% (kale), 22.8% (pear), 14.8% (wheat), and 9.9% (corn) to maximum lignin contents of 6.5% (kale), 16.4% (pear), 4.9% (wheat), and 2.3% (corn). These data demonstrate that certain commonly used statements such as "cereal brans are highly lignified" need to be revised.  相似文献