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971.
Common species have lower taxonomic diversity Evidence from the urban floras of Brussels and Rome 总被引:1,自引:0,他引:1
The species pool hypothesis claims that the large‐scale regional species pool is the chief parameter in determining small‐scale species richness through filtering of species that can persist within a community on the basis of their tolerance of the abiotic environment. Accordingly, different environmental conditions give rise to different species assemblages. From a taxonomic perspective, under the assumption of trait conservatism, co‐occurring species that experience similar environmental conditions are likely to be more taxonomically similar than ecologically distant species. The next step consists in understanding how commonness and rarity of individual species produce the observed taxonomic diversity. In this paper, the importance of environmental filtering in regulating the taxonomic structure of rare and common plant species in the urban floras of Brussels (Belgium) and Rome (Italy) is tested. First, we computed the taxonomic diversity of the rare and common species of Brussels and Rome based on the branching topology of the Linnaean taxonomic trees. Next, using a randomization procedure, we determined whether the taxonomic diversity of the rare species was significantly higher than the diversity of the common species. Results show that, for both urban floras, common species that shape the community matrix and experience similar environmental conditions have a taxonomic diversity that is significantly lower than that of the rare species that represent a relatively incidental set of species of more ‘disperse’ origin. Finally, from a conservation/management perspective our results imply that, given their high taxonomic heterogeneity, the protection of rare species is a central issue for preserving high levels of diversity in urban areas. 相似文献
972.
973.
Adrian L. D. Paul Sandrine Isnard Christine M. Wawryk Peter D. Erskine Guillaume Echevarria Alan J. M. Baker Jason K. Kirby Antony van der Ent 《The Plant journal : for cell and molecular biology》2021,107(4):1040-1055
The hyperaccumulator Pycnandra acuminata is a New Caledonian rainforest tree known to have the highest concentration of nickel in any living organism, with 25 wt% nickel in its latex. All trees (with a diameter of >10 cm) and soil profiles in a 0.25-hectare permanent plot were sampled to assess the biogeochemical compartmentalisation of nickel in a dense stand of P. acuminata trees. Nickel stable isotope analysis permitted insights into the cycling of nickel in this ecosystem. The total tree biomass of the plot was calculated to be 281 tonnes ha−1, which contained 0.44 kg of cobalt, 49.1 kg of manganese, 257 kg of nickel and 6.76 kg of zinc. Nickel stable isotope analysis identified the biotic origin of the nickel in the soil upper layers, with P. acuminata shoots enriched in lighter nickel isotopes. The δ60Ni latex signature suggests that long-distance transport, radial xylem and phloem loading are at play in P. acuminata. 相似文献
974.
975.
Eric Grouzmann Jean‐Baptiste Gualtierotti Sandrine Gerber‐Lemaire Karim Abid Noureddine Brakch Alessandro Pedretti Bernard Testa Giulio Vistoli 《Chirality》2013,25(1):28-34
(1R)‐Normetanephrine is the natural stereoisomeric substrate for sulfotransferase 1A3 (SULT1A3)‐catalyzed sulfonation. Nothing appears known on the enantioselectivity of the reaction despite its potential significance in the metabolism of adrenergic amines and in clinical biochemistry. We confronted the kinetic parameters of the sulfoconjugation of synthetic (1R)‐normetanephrine and (1S)‐normetanephrine by recombinant human SULT1A3 to a docking model of each normetanephrine enantiomer with SULT1A3 and the 3′‐phosphoadenosine‐5′‐phosphosulfate cofactor on the basis of molecular modeling and molecular dynamics simulations of the stability of the complexes. The KM, Vmax, and kcat values for the sulfonation of (1R)‐normetanephrine, (1S)‐normetanephrine, and racemic normetanephrine were similar. In silico models were consistent with these findings as they showed that the binding modes of the two enantiomers were almost identical. In conclusion, SULT1A3 is not substrate‐enantioselective toward normetanephrine, an unexpected finding explainable by a mutual adaptability between the ligands and SULT1A3 through an “induced‐fit model” in the catalytic pocket. Chirality, 25:28‐34, 2012.© 2012 Wiley Periodicals, Inc. 相似文献
976.
Pierre Delattre Nicolas Morellet Peggy Codreanu Sandrine Miot Jean -Pierre Quéré Florent Sennedot Jacques Baudry 《Acta theriologica》2009,54(1):51-60
Vole demographics are often modified close to wooded environments. Population monitoring in such settings reveals substantial
edge effects, although these have seldom been quantified. This study compares the abundance of common voleMicrotus arvalis (Pallas, 1778) populations at various distances from three types of wooded environment (hedgerow, copse and forest) and in
two types of habitat (temporary and permanent grassland). In temporary grassland, substantial edge effects were detected along
the boundaries of forests and hedgerows. At 100 m from the forest edge, voles were twice more abundant than at 50 m, four
times more than at 25 m and eight times more than at 5 m. In permanent grassland, the edge effect was such that voles were
practically absent up to 100 m from the forest edge. For both types of grassland, the edge effect was more pronounced for
forest habitat than for hedgerows, that is, for elements with a large surface area of wooded environment. Our results suggest
that landscape context may greatly affect the local abundance of voles. Given the considerable damage done byM. arvalis, the presence of wooded patches in grassland areas leads to lower vole densities in adjacent areas and this might be an alternative
method to controlM. arvalis as a pest species. 相似文献
977.
Xenie Johnson Guillaume Vandystadt Sandrine Bujaldon Francis-André Wollman Rémi Dubois Pierre Roussel Jean Alric Daniel Béal 《Photosynthesis research》2009,102(1):85-93
Here, we describe a new imaging setup able to assess in vivo photosynthetic activity. The system specifically measures time-resolved
chlorophyll fluorescence in response to light. It is composed of a fast digital camera equipped with a wide-angle lens for
the analysis of samples up to 10 × 10 cm, i.e. entire plants or petri dishes. In the choice of CCD, we have opted for a 12-bits
high frame rate [150 fps (frames per second)] at the expense of definition (640 × 480 pixels). Although the choice of digital
camera is always a compromise between these two related features, we have designed a flexible system allowing the fast sampling
of images (down to 100 μs) with a maximum spatial resolution. This image readout system, synchronized with actinic light and
saturating pulses, allows a precise determination of F
0 and F
M, which is required to monitor PSII activity. This new imaging system, together with image processing techniques, is useful
to investigate the heterogeneity of photosynthetic activity within leaves or to screen large numbers of unicellular algal
mutant colonies to identify those with subtle changes in photosynthetic electron flow. 相似文献
978.
Chloroplast Dysfunction Causes Multiple Defects in Cell Cycle Progression in the Arabidopsis crumpled leaf Mutant 总被引:1,自引:0,他引:1
979.
980.
Filippo Molica Merlijn J.P. Meens Sandrine Morel Brenda R. Kwak 《Biology of the cell / under the auspices of the European Cell Biology Organization》2014,106(9):269-293
Connexins (Cxs) form a family of transmembrane proteins comprising 21 members in humans. Cxs differ in their expression patterns, biophysical properties and ability to combine into homomeric or heteromeric gap junction channels between neighbouring cells. The permeation of ions and small metabolites through gap junction channels or hemichannels confers a crucial role to these proteins in intercellular communication and in maintaining tissue homeostasis. Among others, Cx37, Cx40, Cx43, Cx45 and Cx47 are found in heart, blood and lymphatic vessels. Mutations or polymorphisms in the genes coding for these Cxs have not only been implicated in cardiovascular pathologies but also in a variety of other disorders. While mutations in Cx43 are mostly linked to oculodentodigital dysplasia, Cx47 mutations are associated with Pelizaeus–Merzbacher‐like disease and lymphoedema. Cx40 mutations are principally linked to atrial fibrillation. Mutations in Cx37 have not yet been described, but polymorphisms in the Cx37 gene have been implicated in the development of arterial disease. This review addresses current knowledge on gene mutations in cardiovascular Cxs systematically and links them to alterations in channel properties and disease. 相似文献