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1.
Moran Jonathan A.; Merbach Marlis A.; Livingston Nigel J.; Clarke Charles M.; Booth Webber E. 《Annals of botany》2001,88(2):307-311
Old World pitcher plants (Nepenthes spp., Nepenthaceae) trapand digest invertebrate prey to derive nutrients, primarilynitrogen (N). In the majority of lowland Nepenthes species studiedto date, ants (Hymenoptera, Formicidae) are numerically thedominant prey taxon. Nepenthes albomarginata is unusual in showingan apparent bias towards the capture of termites (Isoptera).We tested the hypothesis that N. albomarginata derives N fromtermite capture, by comparison of foliar stable N isotope abundance( 相似文献
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Adam NR Wall GW Kimball BA Pinter PJ Lamorte RL Hunsaker DJ Adamsen FJ Thompson T Matthias AD Leavitt SW Webber AN 《Photosynthesis research》2000,66(1-2):65-77
We have examined the photosynthetic acclimation of wheat leaves grown at an elevated CO2 concentration, and ample and limiting N supplies, within a field experiment using free-air CO2 enrichment (FACE). To understand how leaf age and developmental stage affected any acclimation response, measurements were
made on a vertical profile of leaves every week from tillering until maturity. The response of assimilation (A) to internal
CO2 concentration (Ci) was used to estimate the in vivo carboxylation capacity (Vcmax) and maximum rate of ribulose-1,5-bisphosphate limited photosynthesis (A
sat). The total activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), and leaf content of Rubisco and the Light
Harvesting Chlorophyll a/b protein associated with Photosystem II (LHC II), were determined. Elevated CO2 did not alter Vcmax in the flag leaf at either low or high N. In the older shaded leaves lower in the canopy, acclimatory decline in Vcmax and A
sat was observed, and was found to correlate with reduced Rubisco activity and content. The dependency of acclimation on N supply
was different at each developmental stage. With adequate N supply, acclimation to elevated CO2 was also accompanied by an increased LHC II/Rubisco ratio. At low N supply, contents of Rubisco and LHC II were reduced in
all leaves, although an increased LHC II/Rubisco ratio under elevated CO2 was still observed. These results underscore the importance of leaf position, leaf age and crop developmental stage in understanding
the acclimation of photosynthesis to elevated CO2 and nutrient stress.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
Cytologic diagnosis of Pneumocystis carinii infection by bronchoalveolar lavage in acquired immune deficiency syndrome 总被引:2,自引:0,他引:2
Twenty-six patients with pulmonary infiltrates and suspected acquired immune deficiency syndrome (AIDS) underwent 29 fiberoptic bronchoscopies, including bronchoalveolar lavage. Seventeen of the 18 patients (94.4%) shown to have Pneumocystis carinii pneumonia were diagnosed by examination of the bronchoalveolar lavage specimen. Minor complications occurred in 7 of 29 total bronchoscopies and included transient fever and hypoxemia. Bronchoalveolar lavage is a safe, easy and effective procedure for making the diagnosis of P. carinii pneumonia in patients at high risk for AIDS and should be included routinely when performing fiberoptic bronchoscopy. 相似文献
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K C Nicolaou B E Marron C A Veale S E Webber S E Dahlén B Samuelsson C N Serhan 《Biochimica et biophysica acta》1989,1003(1):44-53
Addition of (15S)-hydroxy-5,8,11-cis-13-trans-eicosatetraenoic acid (15-HETE) and the ionophore A23187 (2.5 microM) to human neutrophils led to the formation of both lipoxin A4 and lipoxin B4 as well as a novel 5,6,15-trihydroxyeicosatetraenoic acid. The new compound was identified using an improved isolation and detection system and its basic structure was determined by physical methods. On the basis of biosynthetic considerations, geometric isomers of lipoxin A4 and lipoxin B4 were prepared by total synthesis. Comparison of these synthetic materials with the neutrophil-derived product showed that the new compound is (5S,6R,15S)-trihydroxy-9,11,13-trans-7-cis-eicosatetraenoic acid or the 7-cis-11-trans-isomer of LXA4 (7-cis-11-trans-LXA4). LXA4, 11-trans-LXA4, 7-cis-LXA4 and 7-cis-11-trans-LXA4 all evoked dose-dependent (0.1-10 microM) contractions of the guinea pig lung strip, whereas 6-cis-LXB4 and 6-cis-8-trans-LXB4 relaxed this preparation. LXA4 and 7-cis-LXA4 were approx. 10-times more potent than the compounds with 11-trans geometry. However, all four double-bond isomers of LXA4 caused contractions which, based upon pharmacological evidence, appeared to involve specific activation of the same site as cysteinyl-containing leukotrienes. In conclusion, 7-cis-11-trans-LXA4 was isolated and identified as a novel biologically active eicosanoid formed by human neutrophils. 相似文献
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BORIS KRYTUFEK ELENA V. BUAN VLADIMÍR VOHRALÍK ROGHAIEH ZAREIE BEYTULLAH ÖZKAN 《Biological journal of the Linnean Society. Linnean Society of London》2009,98(1):121-128
We established a cytochrome b (cyt b ) phylogeny for six species of social voles. A Bayesian approach to phylogenetic reconstruction (BI) and a maximum likelihood (ML) tree revealed a dichotomy into two major clusters, namely a Microtus guentheri cluster and a M. socialis cluster. The three main lineages that emerged within each of these two clusters were separated by the K2P divergences which are above the intraspecific variation in Microtus . All six species were also retrieved in the minimum spanning network. Within its present taxonomic scope, M. guentheri is paraphyletic and consists of two allopatric sibling species: M. guentheri (Syria, Israel) and M. hartingi (Anatolia and the Balkans). The closest relative to these two species is M. dogramacii , which is possibly a sister species to M. hartingi . The two geographic samples were identified as M. irani , one from Shiraz (Iran) and the other from Balkusan (Turkey). The cyt b sequence confirmed the specific status of M. anatolicus within the M. socialis cluster. Although five species of social voles occur within a radius of < 500 km in the north-eastern corner of the Mediterranean, small-scale sympatry is exceptional. Species richness in this region possibly originates from past fragmentation with subsequent allopatric speciation in refugial areas. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 121–128. 相似文献
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The level of hypoglycaemia required to elicit gastric secretion of acid and pepsin was studied in urethane-anaesthetized rats. Hypoglycaemia was induced by intravenous injection of insulin or by electrical stimulation of the posterior hypothalamus. In each case the blood glucose values below which gastric secretion was stimulated were significantly higher for pepsin than for acid secretion. This consistently resulted in the onset of pepsin secretion in advance of the onset of acid secretion. These observations suggest that the production of the different components of the gastric juice was under the influence of either separate hypothalamic glucoreceptors, or a single set of glucoreceptors able to respond selectively to different blood glucose levels. 相似文献