ORIGIN OF A TETRAPLOID SHOOT FROM THE REGION OF A TUMOR ON TOMATO     

Kostoff D  Kendall J 《Science (New York, N.Y.)》1932,76(1963):144-145

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A whiff of oxygen before the great oxidation event?   总被引：1，自引：0，他引：1  

Anbar AD  Duan Y  Lyons TW  Arnold GL  Kendall B  Creaser RA  Kaufman AJ  Gordon GW  Scott C  Garvin J  Buick R 《Science (New York, N.Y.)》2007,317(5846):1903-1906

High-resolution chemostratigraphy reveals an episode of enrichment of the redox-sensitive transition metals molybdenum and rhenium in the late Archean Mount McRae Shale in Western Australia. Correlations with organic carbon indicate that these metals were derived from contemporaneous seawater. Rhenium/osmium geochronology demonstrates that the enrichment is a primary sedimentary feature dating to 2501 +/- 8 million years ago (Ma). Molybdenum and rhenium were probably supplied to Archean oceans by oxidative weathering of crustal sulfide minerals. These findings point to the presence of small amounts of O2 in the environment more than 50 million years before the start of the Great Oxidation Event.  相似文献   

SEPARATIONS BY THE IONIC MIGRATION METHOD     

Kendall J 《Science (New York, N.Y.)》1928,67(1728):163-167

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De novo computational design of retro-aldol enzymes     

Jiang L  Althoff EA  Clemente FR  Doyle L  Röthlisberger D  Zanghellini A  Gallaher JL  Betker JL  Tanaka F  Barbas CF  Hilvert D  Houk KN  Stoddard BL  Baker D 《Science (New York, N.Y.)》2008,319(5868):1387-1391

The creation of enzymes capable of catalyzing any desired chemical reaction is a grand challenge for computational protein design. Using new algorithms that rely on hashing techniques to construct active sites for multistep reactions, we designed retro-aldolases that use four different catalytic motifs to catalyze the breaking of a carbon-carbon bond in a nonnatural substrate. Of the 72 designs that were experimentally characterized, 32, spanning a range of protein folds, had detectable retro-aldolase activity. Designs that used an explicit water molecule to mediate proton shuffling were significantly more successful, with rate accelerations of up to four orders of magnitude and multiple turnovers, than those involving charged side-chain networks. The atomic accuracy of the design process was confirmed by the x-ray crystal structure of active designs embedded in two protein scaffolds, both of which were nearly superimposable on the design model.  相似文献   

Precision agriculture technology adoption: a qualitative study of small-scale commercial “family farms” located in the North China Plain     

Kendall  Helen  Clark  Beth  Li  Wenjing  Jin  Shan  Jones  Glyn. D.  Chen  Jing  Taylor  James  Li  Zhenhong  Frewer  Lynn. J. 《Precision Agriculture》2022,23(1):319-351

Precision Agriculture - Precision agriculture (PA) technologies offer a potential solution to food security and environmental challenges but, will only be successful if adopted by farmers. Adoption...  相似文献   

Salish Sea Chinook salmon exhibit weaker coherence in early marine survival trends than coastal populations          下载免费PDF全文

Casey P. Ruff  Joseph H. Anderson  Iris M. Kemp  Neala W. Kendall  Peter A. Mchugh  Antonio Velez‐Espino  Correigh M. Greene  Marc Trudel  Carrie A. Holt  Kristen E. Ryding  Kit Rawson 《Fisheries Oceanography》2017,26(6):625-637

Identifying factors that influence anadromous Pacific salmon (Oncorhynchus spp.) population dynamics is complicated by their diverse life histories and large geographic range. Over the last several decades, Chinook salmon (O. tshawytscha) populations from coastal areas and the Salish Sea have exhibited substantial variability in abundance. In some cases, populations within the Salish Sea have experienced persistent declines that have not rebounded. We analyzed a time series of early marine survival from 36 hatchery Chinook salmon populations spanning ocean entry years 1980–2008 to quantify spatial and temporal coherence in survival. Overall, we observed higher inter‐population variability in survival for Salish Sea populations than non‐Salish Sea populations. Annual survival patterns of Salish Sea populations covaried over smaller spatial scales and exhibited less synchrony among proximate populations relative to non‐Salish Sea populations. These results were supported by multivariate autoregressive state space (MARSS) models which predominantly identified region‐scale differences in survival trends between northern coastal, southern coastal, Strait of Georgia, and Puget Sound population groupings. Furthermore, Dynamic Factor Analysis (DFA) of regional survival trends showed that survival of southern coastal populations was associated with the North Pacific Gyre Oscillation, a large‐scale ocean circulation pattern, whereas survival of Salish Sea populations was not. In summary, this study demonstrates that survival patterns in Chinook salmon are likely determined by a complex hierarchy of processes operating across a broad range in spatial and temporal scales, presenting challenges to the management of mixed‐stock fisheries.  相似文献   

The importance of bare marine sedimentary habitats for maintaining high polychaete diversity and the implications for the design of marine protected areas     

Christopher R. S. Barrio Froján  Mike A. Kendall  Gordon L. J. Paterson  Lawrence E. Hawkins  Sompoch Nimsantijaroen  Chittima Aryuthaka 《水产资源保护:海洋与淡水生态系统》2009,19(7):748-757

• 1. Bare intertidal sedimentary habitats have received relatively little attention compared with their neighbouring vegetated habitats. An ecological comparison of benthic faunal assemblages inhabiting tropical intertidal seagrass beds and bare sediments has been made to assess the faunal similarity between the two habitats in south‐east Asia.
• 2. The poorly developed taxonomy of most invertebrate taxa in the region precluded the full identification of many faunal groups. Only the polychaetes — which accounted for 76% of all the macrofaunal organisms collected — were identified to the lowest possible taxonomic level, yielding 177 nominal species belonging to 35 families. Ecological analyses suggested that although each habitat had a distinct polychaete assemblage, there were few differences between habitats based on a range of calculated assemblage diversity metrics.
• 3. Further analyses were applied to the data to test the performance of three strategies for optimizing the selection of sites for inclusion in potential marine protected areas. Strategies were based either on the total number of species, the number of rare or endemic species, or on the level of species richness (used as a surrogate for community structure).
• 4. All three strategies consistently captured above average numbers of species at most levels of conservation intensity. The merits of each strategy are considered in turn.

Copyright © 2009 John Wiley & Sons, Ltd.  相似文献