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1.
Patricia Pacheco Daniel J. Crawford Tod F. Stuessy Mario Silva O. 《American journal of botany》1991,78(4):534-543
Leaf flavonoid chemistry was examined from the three subgenera and 11 species of the endemic genus Dendroseris (Compositae, Lactuceae) of the Juan Fernandez Islands, Chile. Eight of the species are restricted to the older island (Masatierra, ca. 4 million years old), which is also closer to the mainland. Three species, one from each subgenus, are restricted to Masafuera, which is younger geologically (1–2 million years old) and 145 km further west of Masatierra. A total of 16 compounds was identified, with the 7-0-glucosides of the flavones apigenin and luteolin accounting for 12 of the constituents. Two glucosides of the flavonol quercetin were detected. Despite considerable interpopulation variation within species, six of the taxa have distinctive flavonoid profiles. Although there are few absolute differences among the subgenera, they can be distinguished chemically. Subgenus Rea contains the greatest number of compounds, and a previous cladistic analysis based on morphological features suggested this subgenus as most primitive. Subgenus Phoenicoseris is considered highly derived morphologically, and it has a reduced flavonoid chemistry. Very little reduction in flavonoid diversity was seen in the morphologically specialized subg. Dendroseris as compared to subg. Rea. A trend in reduction of numbers of compounds was seen for two of the three species on the younger island of Masafuera when compared to their presumed ancestors on Masatierra. Flavonoids of selected species of Hieracium and Hypochaeris, presumptive mainland progenitors of Dendroseris, reveal a close chemical affinity with the former genus. 相似文献
2.
Tod M. L.; McGeady M. L.; Rock P.; Sylvester J. T. 《Journal of applied physiology》1987,63(4):1387-1395
The effects of embolization on the longitudinal distribution of pulmonary vascular pressures with respect to vascular compliance were determined by the vascular inflow and outflow occlusion technique in isolated blood-perfused pig lungs treated with papaverine to prevent vasomotor responses. Embolization with microspheres having mean diameters of 75, 200, and 550 microns and with barrier beads (2 X 3 X 3.5 mm) significantly increased the pressure gradient across the relatively compliant middle region (delta Pm) without increasing the gradients across the relatively noncompliant regions on the arterial (delta Pa) or venous (delta Pv) ends of the vasculature. In contrast ligation of several lobar arteries caused delta Pa to increase from 0.9 +/- 0.3 to 5.9 +/- 1.1 mmHg but did not change delta Pm or delta Pv. Assuming that delta Pa and delta Pv measured by vascular occlusion result from cessation of flow through resistances, these data suggest that in isolated pig lungs the vessels at the boundary between the arterial and middle regions defined by the occlusion technique are arteries greater than 2-3 mm diam and smaller than lobar arteries. 相似文献
3.
Yuelong Yang Nancy E. Stamp Tod L. Osier 《Entomologia Experimentalis et Applicata》1996,79(3):335-344
To understand the mechanisms underlying plant-insect herbivore interactions, it is necessary to examine the simultaneous effects of temperature, food quality and larval age. We examined the simultaneous effects of three allelochemicals (tomatine, rutin and chlorogenic acid) on the performance of first and second instar Manduca sexta larvae under two representative thermal regimes 21 : 10°C and 26 : 15°C for spring and summer, respectively. Thermal regime and allelochemicals interacted to influence the time from egg hatch to ecdysis to the third instar. On average, it took about half as much time to reach the third instar at 26 : 15°C as it did at 21 : 10°C. Separately, tomatine and rutin had a negative effect on developmental time from egg hatch to the third instar, but their simutaneous effects were not additive. Chlorogenic acid significantly reduced the negative effect of tomatine. The magnitude of the allelochemical effect was larger at the cooler thermal regime compared to the warmer regime. For instance, chlorogenic acid by itself had no effect at the 26 : 15°C regime, but at the 21 : 10°C regime it significantly shortened total developmental time. The effect of chlorogenic acid on stadium duration was distinctly different for the two instars. Chlorogenic acid shortened stadium duration of first instar larvae. However, depending on thermal regime and the presence of tomatine, chlorogenic acid had a negative, positive or neutral effect on stadium duration of second instar larvae. Molting duration of second instar larvae was shortened by a half day at the warmer thermal regime but was not affected by the allelochemicals. Final larval weight was influenced by rutin and chlorogenic acid. Caterpillars fed diets containing 20 moles of rutin were on average 10% lighter than those fed plain diet, whereas those fed diets containing 20 moles of chlorogenic adic were on average 7% heavier. However, the effect of chlorogenic acid depended on thermal regime. Overall, our results indicated that: 1) temperature and food quality can interact to influence insect performance and 2) these effects are influenced by larval age. 相似文献
4.
5.
The flavonoids of three species of Desmanthodium are based upon kaempferol, quercetin and quercetagetin. Sugar substitutions comprise glucosides, galactosides, rhamnosides, rutinosides and diglucosides. Four different O-methylated compounds occur in field populations of the genus, but they are found in all species and are therefore not useful for sectional or subgeneric delimitations. The flavonoid profile of Desmanthodium is very similar to that of Clibadium, which parallels their close morphological affinity. 相似文献
6.
Manuel J. Steinbauer Richard Field John‐Arvid Grytnes Panayiotis Trigas Claudine Ah‐Peng Fabio Attorre H. John B. Birks Paulo A. V. Borges Pedro Cardoso Chang‐Hung Chou Michele De Sanctis Miguel M. de Sequeira Maria C. Duarte Rui B. Elias José María Fernández‐Palacios Rosalina Gabriel Roy E. Gereau Rosemary G. Gillespie Josef Greimler David E. V. Harter Tsurng‐Juhn Huang Severin D. H. Irl Daniel Jeanmonod Anke Jentsch Alistair S. Jump Christoph Kueffer Sandra Nogué Rüdiger Otto Jonathan Price Maria M. Romeiras Dominique Strasberg Tod Stuessy Jens‐Christian Svenning Ole R. Vetaas Carl Beierkuhnlein 《Global Ecology and Biogeography》2016,25(9):1097-1107
7.
Smith SA de Oca AN Reeder TW Wiens JJ 《Evolution; international journal of organic evolution》2007,61(5):1188-1207
Differences in species richness at different elevations are widespread and important for conservation, but the causes of these patterns remain poorly understood. Here, we use a phylogenetic perspective to address the evolutionary and biogeographic processes that underlie elevational diversity patterns within a region. We focus on a diverse but well-studied fauna of tropical amphibians, the hylid frogs of Middle America. Middle American treefrogs show a "hump-shaped" pattern of species richness (common in many organisms and regions), with the highest regional diversity at intermediate elevations. We reconstructed phylogenetic relationships among 138 species by combining new and published sequence data from 10 genes and then used this phylogeny to infer evolutionary rates and patterns. The high species richness of intermediate elevations seems to result from two factors. First, a tendency for montane clades to have higher rates of diversification. Second, the early colonization of montane regions, leaving less time for speciation to build up species richness in lowland regions (including tropical rainforests) that have been colonized more recently. This "time-for-speciation" effect may explain many diversity patterns and has important implications for conservation. The results also imply that local-scale environmental factors alone may be insufficient to explain the high species richness of lowland tropical rainforests, and that diversification rates are lower in earth's most species-rich biome. 相似文献
8.
ObjectivesTo identify factors within the South Yorkshire coalfields that influence use of health services by people with angina.DesignQualitative study using semistructured individual and group interviews.SettingGeneral practice and community settings in Barnsley and Rotherham health authorities.Participants14 patients with stable angina and nine primary care staff had individual interviews plus five community groups and one group of general practitioners.ResultsA complex web of factors was identified that prevented, delayed, or facilitated referral to secondary care. Delay, denial, and self management by patients meant that the full extent of symptoms often remained hidden from general practitioners, resulting in a delayed or missed referral. Barriers identified fell into six categories: structural, personal, social and cultural, past experience and expectations, diagnostic confusion, and knowledge and awareness.ConclusionsMany of the factors influencing referral operate before general practitioners become involved. Community development could be one way of tackling inequalities and promoting sustainable change. Structural changes are needed to improve access and increase the acceptability of general practice services. Primary care staff should be educated to detect underreporting of symptoms and promote appropriate referral.
What is already known on this topic
An inverse correlation has been shown between deprivation and cardiac revascularisationFear of hospitals, denial of ill health, and low expectations may prevent people with angina accessing health servicesWhat this study adds
Fear, denial, and low expectations were important barriers to accessing health services, reinforcing earlier findingsOther factors may be specific to the study population—for example, coping, independence, and attributing symptoms to industrially related lung diseaseMany of the barriers operate before general practitioners are involved, making it difficult to identify solutions 相似文献9.
Requirement for PAK4 in the anchorage-independent growth of human cancer cell lines 总被引:10,自引:0,他引:10
Callow MG Clairvoyant F Zhu S Schryver B Whyte DB Bischoff JR Jallal B Smeal T 《The Journal of biological chemistry》2002,277(1):550-558
p21-activated protein kinase (PAK) serine/threonine kinases are important effectors of Rho family GTPases and have been implicated in the regulation of cell morphology and motility, as well as in cell transformation. To further investigate the possible involvement of PAK kinases in tumorigenesis, we analyzed the expression of several family members in tumor cell lines. Here we demonstrate that PAK4 is frequently overexpressed in human tumor cell lines of various tissue origins. We also have identified serine (Ser-474) as the likely autophosphorylation site in the kinase domain of PAK4 in vivo. Mutation of this serine to glutamic acid (S474E) results in constitutive activation of the kinase. Phosphospecific antibodies directed against serine 474 detect activated PAK4 on the Golgi membrane when PAK4 is co-expressed with activated Cdc42. Furthermore, expression of the active PAK4 (S474E) mutant has transforming potential, leading to anchorage-independent growth of NIH3T3 cells. A kinase-inactive PAK4 (K350A,K351A), on the other hand, efficiently blocks transformation by activated Ras and inhibits anchorage-independent growth of HCT116 colon cancer cells. Taken together, our data strongly implicate PAK4 in oncogenic transformation and suggest that PAK4 activity is required for Ras-driven, anchorage-independent growth. 相似文献
10.
Leighfield TA Barbier M Van Dolah FM 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2002,133(3):317-324
A cAMP dependent protein kinase (PKA) was identified in the dinoflagellate Amphidinium operculum. In vitro kinase activity towards kemptide, a PKA-specific substrate, was not detectable in crude lysates. However, fractionation of dinoflagellate extracts by gel filtration chromatography showed PKA-like activity toward kemptide at approximately 66 kDa. These findings suggest that possible low molecular mass inhibitors in crude lysates were removed by the gel filtration chromatography. Pre-incubation of extracts with cAMP prior to chromatography resulted in an apparent molecular mass shift in the in vitro kinase assay to 40 kDa. An in-gel kinase assay reflected activity of the free catalytic subunit at approximately 40 kDa. Furthermore, western blotting with an antibody to the human PKA catalytic subunit confirmed a catalytic subunit with a mass of approximately 40 kDa. Results from this study indicate that the PKA in A. operculatum has a catalytic subunit of similar size to that in higher eukaryotes, but with a holoenzyme of a size suggesting a dimeric, rather than tetrameric structure. 相似文献