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141.
142.
E. R. Jasper Wubs Wim H. van der Putten Simon R. Mortimer Gerard W. Korthals Henk Duyts Roel Wagenaar T. Martijn Bezemer 《Ecology letters》2019,22(7):1145-1151
Recent demonstrations of the role of plant–soil biota interactions have challenged the conventional view that vegetation changes are mainly driven by changing abiotic conditions. However, while this concept has been validated under natural conditions, our understanding of the long‐term consequences of plant–soil interactions for above‐belowground community assembly is restricted to mathematical and conceptual model projections. Here, we demonstrate experimentally that one‐time additions of soil biota and plant seeds alter soil‐borne nematode and plant community composition in semi‐natural grassland for 20 years. Over time, aboveground and belowground community composition became increasingly correlated, suggesting an increasing connectedness of soil biota and plants. We conclude that the initial composition of not only plant communities, but also soil communities has a long‐lasting impact on the trajectory of community assembly. 相似文献
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With the increasing frequency of large‐scale restoration efforts, the need to understand the adaptive genetic structure of natural plant populations and their relation to heavily utilized cultivars is critical. Bouteloua gracilis (blue grama) is a wind‐dispersed, perennial grass consisting of several cytotypes (2n = 2×–6×) with a widespread distribution in western North America. The species is locally dominant and used regularly in restoration treatments. Using amplified fragment length polymorphism (AFLP) and cpDNA analyses, we assessed the genetic variability and adaptive genetic structure of blue grama within and among 44 sampling sites that are representative of the species’ environmental and habitat diversity in the southwestern United States. Five cultivars were also included to investigate genetic diversity and differentiation in natural versus cultivated populations. Three main findings resulted from this study: (a) Ninety‐four polymorphic AFLP markers distinguished two population clusters defined largely by samples on and off the Colorado Plateau; (b) substructure of samples on the Colorado Plateau was indicated by genetic divergence between boundary and interior regions, and was supported by cytotype distribution and cpDNA analysis; and (c) six AFLP markers were identified as “outliers,” consistent with being under selection. These loci were significantly correlated to mean annual temperature, mean annual precipitation, precipitation of driest quarter, and precipitation of wettest quarter in natural populations, but not in cultivated samples. Marker × environment relationships were found to be largely influenced by cytotype and cultivar development. Our results demonstrate that blue grama is genetically variable, and exhibits genetic structure, which is shaped, in part, by environmental variability across the Colorado Plateau. Information from our study can be used to guide the selection of seed source populations for commercial development and long‐term conservation management of B. gracilis, which could include genetic assessments of diversity and the adaptive potential of both natural and cultivated populations for wildland restoration. 相似文献
145.
Bermek O Diamantopoulou Z Polykratis A Dos Santos C Hamma-Kourbali Y Burlina F Delbé J Chassaing G Fernig DG Katsoris P Courty J 《Experimental cell research》2007,313(19):4041-4050
Heparin affin regulatory peptide (HARP) is an 18 kDa heparin-binding protein that plays a key role in tumor growth. We showed previously that the synthetic peptide P(111-136) composed of the last 26 HARP amino acids inhibited HARP-induced mitogenesis. Here, to identify the exact molecular domain involved in HARP inhibition, we investigated the effect of the shorter basic peptide P(122-131) on DU145 cells, which express HARP and its receptor protein tyrosine phosphatase beta/zeta (RPTPbeta/zeta). P(122-131) was not cytotoxic; it dose-dependently inhibited anchorage-independent growth of DU145 cells. Binding studies using biotinylated P(122-131) indicated that this peptide interfered with HARP binding to DU145 cells. Investigation of the mechanisms involved suggested interference, under anchorage-independent conditions, of P(122-131) with a HARP autocrine loop in an RPTPbeta/zeta-dependent fashion. Thus, P(122-131) may hold potential for the treatment of disorders involving RPTPbeta/zeta. 相似文献
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Dick H J Thijssen Gerard A Rongen Arie van Dijk Paul Smits Maria T E Hopman 《Journal of applied physiology》2007,103(3):852-857
Advanced age is associated with a decreased leg blood flow and reduced physical activity. Endothelin (ET-1), a powerful vasoconstrictor, may play a role in the increased leg vascular tone in older men. objectives: to assess the ET-1-mediated vascular tone in the legs of healthy sedentary older men, both before and after 8 wk of exercise training. methods: in 8 younger subjects (19-50 yr) and 8 older men (67-76 yr), bilateral leg blood flow was measured using venous occlusion plethysmography before and after antagonizing ET-1 (using selective ET(A/B)-receptor antagonists). In older men, reversibility of the observations was assessed after 8 wk of cycling. results: ET-receptor inhibition increased leg blood flow significantly more in older men compared with younger individuals (29 +/- 9% and 10 +/- 4%, respectively, P < 0.05). Eight-week cycling training increased baseline blood flow in older men. The blood flow response to ET-receptor inhibition in older men was not affected by the training program (25 +/- 8%, P > 0.05 for comparison with pretraining). The flow ratio (blood flows infused leg/noninfused leg) decreased significantly by training from 26 +/- 8% to 7+3% (P < 0.05). CONCLUSION: the increased baseline vascular tone in aging is at least in part mediated by the endothelin. Eight-weeks cycling training in older sedentary men decreased leg vascular tone and seems to partly decrease the ET-1-mediated vascular tone. 相似文献
148.
Gerard T. Haymes Paul H. Patrick Lawrence J. Onisto 《International Review of Hydrobiology》1984,69(6):867-876
Laboratory and field tests were conducted to determine the effectiveness of filtered mercury vapour lights in attracting fish with possible utilization in a fish conserving scheme at an electrical generating station. In laboratory tests, alewife demonstrated an attraction to the mercury vapour light which was associated with an increase in swimming activity. This response was maintained over a 48-hour period. When the filtered mercury vapour lights were utilized in association with a fish pump in the Nanticoke Generating Station forebay, juvenile gizzard shad and smelt were attracted to the pump area. Although there was variation with time of day, tubidity and lighting array; the results suggested that the number of fish passing through the pump increased when the mercury vapour lights alone or when the mercury lights in association with a white strobe light were employed. 相似文献
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The chirality of the title heterocycles is discussed considering their genesis by desymmetrization of the corresponding adamantanes. Some rules for the specification of the absolute configurations of the enantiomers (R or S) for this type of compounds are proposed. © 1996 Wiley-Liss, Inc. 相似文献