排序方式: 共有22条查询结果,搜索用时 15 毫秒
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GUILLAUME TCHERKEZ RUDI SCHÄUFELE SALVADOR NOGUÉS CLÉMENT PIEL ARNOUD BOOM GARY LANIGAN CÉCILE BARBAROUX CATARINA MATA SLIMAN ELHANI DEBBIE HEMMING CHRISTINA MAGUAS DAN YAKIR FRANZ W. BADECK HOWARD GRIFFITHS HANS SCHNYDER JALEH GHASHGHAIE 《Plant, cell & environment》2010,33(6):900-913
While there is currently intense effort to examine the 13C signal of CO2 evolved in the dark, less is known on the isotope composition of day‐respired CO2. This lack of knowledge stems from technical difficulties to measure the pure respiratory isotopic signal: day respiration is mixed up with photorespiration, and there is no obvious way to separate photosynthetic fractionation (pure ci/ca effect) from respiratory effect (production of CO2 with a different δ13C value from that of net‐fixed CO2) at the ecosystem level. Here, we took advantage of new simple equations, and applied them to sunflower canopies grown under low and high [CO2]. We show that whole mesocosm‐respired CO2 is slightly 13C depleted in the light at the mesocosm level (by 0.2–0.8‰), while it is slightly 13C enriched in darkness (by 1.5–3.2‰). The turnover of the respiratory carbon pool after labelling appears similar in the light and in the dark, and accordingly, a hierarchical clustering analysis shows a close correlation between the 13C abundance in day‐ and night‐evolved CO2. We conclude that the carbon source for respiration is similar in the dark and in the light, but the metabolic pathways associated with CO2 production may change, thereby explaining the different 12C/13C respiratory fractionations in the light and in the dark. 相似文献
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LIZE JOUBERT H. JOHAN T. VENTER RUDI L. VERHOEVEN 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(2):343-346
A new species of Cryptolepis is described from Kenya and Tanzania. It is a tropical forest climber and its unique second corona whorl of deeply cleft lobes distinguishes it from all other Cryptolepis species. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 343–346. 相似文献
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MAARTEN T.BASTIAENS RUDI G.J. WESTENDORP BERT J. VERMEER JAN N. BOUWES BAVINCK 《Pigment cell & melanoma research》1999,12(5):316-322
Ephelides and solar lentigines are benign pigmented spots, which are currently associated with an increased risk of skin cancer. These two pigmented spots are known to be discriminated by their clinical, histological, and electron microscopic characteristics, even though occasional misclassification can occur because of their similarity. It has also been questioned whether these spots are not one and the same. In this study, we have attempted to differentiate between these two pigmented spots with the use of a standardized protocol for clinical examinations on 272 healthy volunteers, paying particular consideration to their pigmentary and constitutional host factors. We found that solar lentigines 1) are more prevalent than ephelides, 2) increase in prevalence and number with higher age, and 3) are most prevalent on the trunk and occur more frequently in males than in females. A trend is also observed whereby ephelides 1) loose their prevalence with age, 2) become equally distributed on the face, arms, and trunk, and 3) occur more frequently in females. An intimate association of ephelides, but not solar lentigines, has been found with hair color and skin type. All of these findings are in agreement with most of those reported in the literature, supporting the view that ephelides and solar lentigines are different types of pigmented lesions. 相似文献
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HANS SCHNYDER MICHAEL SCHWERTL KARL AUERSWALD RUDI SCHÄUFELE 《Global Change Biology》2006,12(7):1315-1329
The carbon isotope composition (δ13C) of C3 ecosystems is sensitive to water availability, and provides important information for the assessment of terrestrial carbon (C) sink/source activity. Here, we report the effects of plant available soil water (PAW) on community 13C signatures of temperate humid grassland. The 5‐year study was conducted on pastures exhibiting a large range of PAW capacity that were located on two site types: peat and mineral soils. The data set included the centennial drought year 2003, and data from wet years (2000 and 2002). Seasonal variation of PAW was modeled using PAW capacity of each pasture, precipitation inputs and evapotranspiration estimates. Community 13C signatures were derived from the δ13C of vegetation and segments of tail switch hair of cattle grown while grazing pastures. Hair 13C signatures provided an assimilation‐weighted 13C signal that integrated both spatial (paddock‐scale) and temporal (grazing season) variation of 13C signatures on a pasture. The δ13C of hair and vegetation increased with decreasing modeled PAW in the same way on mineral and peat soils. But, at a given PAW, the δ13C of hair was 2.6‰ less negative than that of vegetation, reflecting the diet‐hair isotopic shift. Furthermore, the δ13C of hair and vegetation on peat soil pastures was 0.5‰ more negative than on pastures situated on mineral soil. This may have resulted from a ~10 ppm CO2 enrichment of canopy air derived from ongoing peat mineralization. Community‐scale season‐mean 13C discrimination (Δ) exhibited a saturation‐type response towards season‐mean modeled PAW (r2=0.78), and ranged between 19.8‰ on soils with low PAW capacity during the drought year of 2003, and 21.4‰ on soils with high PAW capacity in a wet year. This indicated relatively small variation in season‐mean assimilation‐weighted pi/pa (0.68–0.75) between contrasting sites and years. However, this range is similar to that reported in other studies, which encompass the range from subtropical arid to humid temperate grassland. Furthermore, the tight relationship between season‐mean Δ and modeled mean PAW suggests that PAW may be used as proxy for Δ. 相似文献
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CHOLINESTERASES IN RETICULAR NERVE CELLS 总被引:1,自引:1,他引:0
RUDI PAVLIN 《Journal of neurochemistry》1965,12(6):515-518
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TJISSE VAN DER HEIDE RUDI M. M. ROIJACKERS EDWIN T. H. M. PEETERS EGBERT H. VAN NES 《Freshwater Biology》2006,51(1):110-116
1. Wilf & Labandeira (1999) suggested that increased temperatures because of global warming will cause an increase in herbivory by insects. This conclusion was based on the supposed effect of temperature on herbivores but did not consider an effect of temperature on plant growth. 2. We studied the effect of temperature on grazing pressure by the small China‐mark moth (Cataclysta lemnata L.) on Lemna minor L. in laboratory experiments. 3. Between temperatures of 15 and 24 °C we found a sigmoidal increase in C. lemnata grazing rates, and an approximately linear increase in L. minor growth rates. Therefore, an increase in temperature did not always result in higher grazing pressure by this insect as the regrowth of Lemna changes also. 4. At temperatures below 18.7 °C, Lemna benefited more than Cataclysta from an increase in temperature, causing a decrease in grazing pressure. 5. In the context of global warming, we conclude that rising temperatures will not necessarily increase grazing pressure by herbivorous insects. 相似文献