Conservation of Northern European plant diversity: the correspondence with soil pH     

Meelis Prtel  Aveliina Helm  Nele Ingerpuu  Ülle Reier  Eva-Liis Tuvi 《Biological conservation》2004,120(4):525-531

Effective biodiversity conservation requires an analysis of the existing reserve system. In temperate and boreal regions, plant diversity has a strong positive association with soil pH. Consequently, in order to protect plant diversity effectively, a relatively large proportion of protected areas should be on high pH soils. Since biodiversity data are never complete for all taxa, biodiversity indicators, e.g., threatened species, should be used. We studied soil pH distributions in protected areas in Northern Europe and tested whether soil pH requirement differs between threatened and non-threatened bryophyte and vascular plant species. As result, the proportion of high pH soils in protected areas was significantly greater than the proportion of these soils in general. This ensures that a large regional pool of plant species preferring high pH soils is relatively well protected. Threatened and non-threatened species in Northern Europe did not differ in their soil pH requirements, but threatened species required a narrower soil pH range than non-threatened species. Consequently, threatened species diversity can be used for indicating overall plant diversity.  相似文献   

Isolation of 4-methylthio-3-butenyl glucosinolate from Raphanus sativus sprouts (kaiware daikon) and its redox properties     

Barillari J  Cervellati R  Paolini M  Tatibouët A  Rollin P  Iori R 《Journal of agricultural and food chemistry》2005,53(26):9890-9896

The most promising among glucosinolates (GLs) are those bearing in their aglycon an extra sulfur function, such as glucoraphasatin (4-methylthio-3-butenyl GL; GRH) and glucoraphenin (4-methylsulfinyl-3-butenyl GL; GRE). The GRE/GRH redox couple is typically met among secondary metabolites of Raphanus sativus L. and, whereas GRE prevails in seeds, GRH is the major GL in full-grown roots. During the 10 days of sprouting of R. sativus seeds, the GRE and GRH contents were determined according to the Eurpean Union official method (ISO 9167-1). In comparison to the seeds, the GRE content in sprouts decreased from about 90 to about 12 micromol g(-1) of dry weight (dw), whereas a 25-fold increase--from about 3 to 76 micromol g(-1) of dw--of the GRH content was measured. An efficient pure GRH gram-scale production process from R. sativus (kaiware daikon) sprouts resulted in significant yield improvement of up to 2.2% (dw basis). The reaction of GRH with both H2O2 and ABTS*+ radical cation was investigated. Whereas H2O2 oxidation of GRH readily resulted in complete transformation into GRE, ABTS*+ caused complete decay of the GL. Even though not directly related to its radical scavenging activity, the assessed reducing capacity of GRH suggests that R. sativus sprouts might possess potential for health benefits.  相似文献   

Enzyme-induced gelation of extensively hydrolyzed whey proteins by Alcalase: peptide identification and determination of enzyme specificity     

Doucet D  Otter DE  Gauthier SF  Foegeding EA 《Journal of agricultural and food chemistry》2003,51(21):6300-6308

Extensive hydrolysis of whey protein isolate by Alcalase was shown to induce gelation mainly via hydrophobic interactions. The aim of this work was to characterize the peptides released in order to better understand this phenomenon. The apparent molecular mass distribution indicated that aggregates were formed by small molecular mass peptides (<2000 Da). One hundred and thirty peptides with various lengths were identified by reversed-phase high-performance liquid chromatography coupled with electrospray ionization mass spectrometry. Alcalase was observed to have a high specificity for aromatic (Phe, Trp, and Tyr), acidic (Glu), sulfur-containing (Met), aliphatic (Leu and Ala), hydroxyl (Ser), and basic (Lys) residues. Most peptides had an average hydrophobicity of 1-1.5 kcal/residue and a net charge of 0 at the pH at which gelation occurred (6.0). Therefore, an intermolecular attractive force such as hydrophobic interaction suggests the formation of aggregates that further leads to the formation of a gel.  相似文献   

A NOTE ON THE SURFACE VISCOSITY OF COLLOIDAL SOLUTIONS     

Du Noöo PL 《Science (New York, N.Y.)》1925,61(1570):117-118

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IMMUNOLOGICAL REACTIONS AND VISCOSITY     

du Noüy L 《Science (New York, N.Y.)》1935,82(2124):254-256

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THE SURFACE EQUILIBRIUM OF COLLOIDAL SOLUTIONS. II     

Du Noüy PL 《Science (New York, N.Y.)》1924,60(1554):337-338

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Temporal variability of the Atlantic meridional overturning circulation at 26.5 degrees N   总被引：4，自引：0，他引：4  

Cunningham SA  Kanzow T  Rayner D  Baringer MO  Johns WE  Marotzke J  Longworth HR  Grant EM  Hirschi JJ  Beal LM  Meinen CS  Bryden HL 《Science (New York, N.Y.)》2007,317(5840):935-938

The vigor of Atlantic meridional overturning circulation (MOC) is thought to be vulnerable to global warming, but its short-term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain. We combine continuous measurements of the MOC (beginning in 2004) using the purposefully designed transatlantic Rapid Climate Change array of moored instruments deployed along 26.5 degrees N, with time series of Gulf Stream transport and surface-layer Ekman transport to quantify its intra-annual variability. The year-long average overturning is 18.7 +/- 5.6 sverdrups (Sv) (range: 4.0 to 34.9 Sv, where 1 Sv = a flow of ocean water of 10(6) cubic meters per second). Interannual changes in the overturning can be monitored with a resolution of 1.5 Sv.  相似文献   

Biochemistry. Dicey assemblies     

Janin J 《Science (New York, N.Y.)》2008,319(5860):165-166

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Comparative genomics of trypanosomatid parasitic protozoa     

El-Sayed NM  Myler PJ  Blandin G  Berriman M  Crabtree J  Aggarwal G  Caler E  Renauld H  Worthey EA  Hertz-Fowler C  Ghedin E  Peacock C  Bartholomeu DC  Haas BJ  Tran AN  Wortman JR  Alsmark UC  Angiuoli S  Anupama A  Badger J  Bringaud F  Cadag E  Carlton JM  Cerqueira GC  Creasy T  Delcher AL  Djikeng A  Embley TM  Hauser C  Ivens AC  Kummerfeld SK  Pereira-Leal JB  Nilsson D  Peterson J  Salzberg SL  Shallom J  Silva JC  Sundaram J  Westenberger S  White O  Melville SE  Donelson JE  Andersson B  Stuart KD  Hall N 《Science (New York, N.Y.)》2005,309(5733):404-409

A comparison of gene content and genome architecture of Trypanosoma brucei, Trypanosoma cruzi, and Leishmania major, three related pathogens with different life cycles and disease pathology, revealed a conserved core proteome of about 6200 genes in large syntenic polycistronic gene clusters. Many species-specific genes, especially large surface antigen families, occur at nonsyntenic chromosome-internal and subtelomeric regions. Retroelements, structural RNAs, and gene family expansion are often associated with syntenic discontinuities that-along with gene divergence, acquisition and loss, and rearrangement within the syntenic regions-have shaped the genomes of each parasite. Contrary to recent reports, our analyses reveal no evidence that these species are descended from an ancestor that contained a photosynthetic endosymbiont.  相似文献   

Tracing the origin and fate of NOx in the Arctic atmosphere using stable isotopes in nitrate     

Morin S  Savarino J  Frey MM  Yan N  Bekki S  Bottenheim JW  Martins JM 《Science (New York, N.Y.)》2008,322(5902):730-732

Atmospheric nitrogen oxides (NOx =NO+ NO2) play a pivotal role in the cycling of reactive nitrogen (ultimately deposited as nitrate) and the oxidative capacity of the atmosphere. Combined measurements of nitrogen and oxygen stable isotope ratios of nitrate collected in the Arctic atmosphere were used to infer the origin and fate of NOx and nitrate on a seasonal basis. In spring, photochemically driven emissions of reactive nitrogen from the snowpack into the atmosphere make local oxidation of NOx by bromine oxide the major contributor to the nitrate budget. The comprehensive isotopic composition of nitrate provides strong constraints on the relative importance of the key atmospheric oxidants in the present atmosphere, with the potential for extension into the past using ice cores.  相似文献