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21.
The metabolism of pantothenic acid 总被引:5,自引:0,他引:5
BROWN GM 《The Journal of biological chemistry》1959,234(2):370-378
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Xiphinema americanum is listed as a quarantine nematode by The European Plant Protection Organisation because of its ability to transmit quarantine viruses. Detection of this nematode in soil samples, or in mixed nematode samples extracted from soil, is therefore of paramount importance. We recently described the use of magnetic beads (Dynabeads) in combination with probes such as lectins or antibodies for recovery of small endoparasitic nematodes including Meloidogyne spp. and Globodera rostochiensis from mixed nematode samples. Here we show that magnetic capture can be used with much larger nematodes such as X. americanum. We describe lectins and antisera that bind to the surface of this nematode and show that the antisera can be used in the Dynabeads system to recover and enrich X. americanum from mixed nematode samples. 相似文献
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CECIL H. BROWN 《American anthropologist》1977,79(2):317-342
Folk botanical life-form terms are added to languages in a highly regular manner. The first life-form to be lexically encoded is always "tree"and the second, a small herbaceous plant class (GRERB). The addition of "bush," "vine," and "grass" follows with "vine" always preceding "grass." An explanation of this encoding sequence is proposed which refers to certain general principles of naming-behavior recently outlined by Witkowski and Brown (1977). In addition, size of folk botanical life-form vocabularies is positively correlated with both societal complexity and botanical species diversity. An explanation of these associations is presented . [cognitive anthropology, ethnobotany, folk classification, language universale, language change] 相似文献
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C. S.JONES L. R. NOBLE J. OUMA H. C. KARIUKI R. MIMPFOUNDI D. S. BROWN D. ROLLINSON 《Biological journal of the Linnean Society. Linnean Society of London》1999,68(1-2):215-240
African freshwater snails of the genus Bulinus act as intermediate hosts for schistosomes, trematode parasites responsible for medical and veterinary forms of schistosomiasis. The relationship between these snails and their parasites is an intricate one, with particular species of snail susceptible to infection only by certain species of schistosome. In common with other self-fertile hermaphrodite gastropods, Bulinus consists of a number of closely related species complexes with restricted gene flow between populations of each taxon. Consequently, despite their medical and veterinary importance as intermediate hosts, unambiguous identification and differentiation of planorbid snails such as these remains problematic, often confounding attempts to define the distribution and evolutionary relationships of conchologically similar taxa. Here we consider how morphological methods of discrimination can be used in conjunction with molecular based approaches to improve snail identification, thereby achieving a better understanding of the epidemiology of schistosomiasis. Data are presented from Central and East African taxa which illustrate how PCR-based methods have begun to be used in combination with traditional analyses in an integrated approach to characterize the genus Bulinus , specifically the B. forskalii species group. Particular emphasis is given to the analyses of Random Amplified Polymorphic DNA (RAPDs) and the mitochondrial gene cytochrome oxidase I (COI). 相似文献
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Effect of precipitation variability on net primary production and soil respiration in a Chihuahuan Desert grassland 总被引:2,自引:0,他引:2
MICHELL L. THOMEY SCOTT L. COLLINS RODRIGO VARGAS JENNIFER E. JOHNSON RENEE F. BROWN DONALD O. NATVIG MICHAEL T. FRIGGENS 《Global Change Biology》2011,17(4):1505-1515
Precipitation regimes are predicted to become more variable with more extreme rainfall events punctuated by longer intervening dry periods. Water‐limited ecosystems are likely to be highly responsive to altered precipitation regimes. The bucket model predicts that increased precipitation variability will reduce soil moisture stress and increase primary productivity and soil respiration in aridland ecosystems. To test this hypothesis, we experimentally altered the size and frequency of precipitation events during the summer monsoon (July through September) in 2007 and 2008 in a northern Chihuahuan Desert grassland in central New Mexico, USA. Treatments included (1) ambient rain, (2) ambient rain plus one 20 mm rain event each month, and (3) ambient rain plus four 5 mm rain events each month. Throughout two monsoon seasons, we measured soil temperature, soil moisture content (θ), soil respiration (Rs), along with leaf‐level photosynthesis (Anet), predawn leaf water potential (Ψpd), and seasonal aboveground net primary productivity (ANPP) of the dominant C4 grass, Bouteloua eriopoda. Treatment plots receiving a single large rainfall event each month maintained significantly higher seasonal soil θ which corresponded with a significant increase in Rs and ANPP of B. eriopoda when compared with plots receiving multiple small events. Because the strength of these patterns differed between years, we propose a modification of the bucket model in which both the mean and variance of soil water change as a consequence of interannual variability from 1 year to the next. Our results demonstrate that aridland ecosystems are highly sensitive to increased precipitation variability, and that more extreme precipitation events will likely have a positive impact on some aridland ecosystem processes important for the carbon cycle. 相似文献