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131.
132.
Bricca Alessandro Conti Luisa Tardella Maria Federico Catorci Andrea Iocchi Marco Theurillat Jean-Paul Cutini Maurizio 《Plant Ecology》2019,220(12):1139-1151
Plant Ecology - Community-weighted mean (CWM) and functional diversity (FD) describe the two aspects of plant communities’ functional structure. While they have been often used separately to... 相似文献
133.
Federico Morelli Yanina Benedetti Anders Pape Mller Richard A. Fuller 《Ecology and evolution》2019,9(14):8378-8386
Measuring the extent to which a species is specialized is a major challenge in ecology, with important repercussions for fundamental research as well as for applied ecology and conservation. Here, we develop a multidimensional index of specialization based on five sets of ecological characteristics of breeding bird species. We used two recent databases of species traits of European birds based on foraging ecology, habitat, and breeding characteristics. The indices of specialization were calculated by applying the Gini coefficient, an index of inequality. The Gini coefficient is a measure of statistical dispersion on a scale between 0 and 1, reflecting a gradient from low to high specialization, respectively. Finally, we tested the strength of the phylogenetic signal of each specialization index to understand how the variance of such indices is shared throughout the phylogeny. The methods for constructing and evaluating a multidimensional index of bird specialization could also be applied to other taxa and regions, offering a simple but useful tool, particularly suited for global or biogeographic studies, as a contribution to comparative estimates of the degree of specialization of species. 相似文献
134.
In this paper, we report investigations on the nested structure, the high-definition mapping, and the molecular basis of the classical Giemsa and Reverse bands in human chromosomes. We found the rules according to which the approximately 3,200 isochores of the human genome are assembled in high (850-band) resolution bands, and the latter in low (400-band) resolution bands, so forming the nested mosaic structure of chromosomes. Moreover, we identified the borders of both sets of chromosomal bands at the DNA sequence level on the basis of our recent map of isochores, which represent the highest-resolution, ultimate bands. Indeed, beyond the 100-kb resolution of the isochore map, the guanine and cytosine (GC) profile of DNA becomes turbulent owing to the contribution of specific sequences such as exons, introns, interspersed repeats, CpG islands, etc. The isochore-based level of definition (100 kb) of chromosomal bands is much higher than the cytogenetic definition level (2-3 Mb). The major conclusions of this work concern the high degree of order found in the structure of chromosomal bands, their mapping at a high definition, and the solution of the long-standing problem of the molecular basis of chromosomal bands, as these could be defined on the basis of compositional DNA properties alone. 相似文献
135.
N-type inactivation in voltage-gated K+ (Kv) channels is a widespread means to modulate neuronal excitability and signaling. Here we have shown a novel mechanism of N-type inactivation in a Caenorhabditis elegans Kv channel. The N-terminal sequence of KVS-1 contains a domain of 22 amino acids that resembles the inactivation ball in A-type channels, which is preceded by a domain of eighteen amino acids. Wild type KVS-1 currents can be described as A-type; however, their kinetics are significantly (approximately 5-fold) slower. When the putative inactivation ball is deleted, the current becomes non-inactivating. Inactivation is restored in non-inactivating channels by diffusion of the missing inactivation domain in the cytoplasm. Deletion of the domain in front of the ball speeds inactivation kinetics approximately 5-fold. We conclude that KVS-1 is the first example of a novel type of Kv channel simultaneously possessing an N-inactivating ball preceded by an N inactivation regulatory domain (NIRD) that acts to slow down inactivation through steric mechanisms. 相似文献
136.
Rigamonti D Bolognini D Mutti C Zuccato C Tartari M Sola F Valenza M Kazantsev AG Cattaneo E 《The Journal of biological chemistry》2007,282(34):24554-24562
137.
Fast, efficient and reproducible genetic transformation of Phaseolus spp. by Agrobacterium rhizogenes 总被引:1,自引:0,他引:1
Estrada-Navarrete G Alvarado-Affantranger X Olivares JE Guillén G Díaz-Camino C Campos F Quinto C Gresshoff PM Sanchez F 《Nature protocols》2007,2(7):1819-1824
This transformation procedure generates, with high efficiency (70-90%), hairy roots in cultivars, landraces and accessions of Phaseolus vulgaris (common bean) and other Phaseolus spp. Hairy roots rapidly develop after wounding young plantlets with Agrobacterium rhizogenes, at the cotyledon node, and keeping the plants in high-humidity conditions. Callogenesis always precedes hairy-root formation, and after 15 days, when roots develop at wounded sites, the stem with the normal root is cleaved below the hairy root zone. Transgenic roots and nodules co-transformed with a binary vector can be easily identified using a reporter gene. This procedure, in addition to inducing robust transgenic hairy roots that are susceptible to being nodulated by rhizobia and to fixing nitrogen efficiently, sets the foundation for a high-throughput functional genomics approach on the study of root biology and root-microbe interactions. This protocol can be completed within 30 days. 相似文献
138.
García-Fuentes E García-Almeida JM García-Arnés J García-Serrano S Rivas-Marín J Gallego-Perales JL Rojo-Martínez G Garrido-Sánchez L Bermudez-Silva FJ Rodríguez de Fonseca F Soriguer F 《Obesity (Silver Spring, Md.)》2007,15(10):2391-2395
Objective: Visfatin has shown to be increased in obesity and in type 2 diabetes. The aim of this study was to determine the change in plasma visfatin in severely obese (SO) persons after weight loss following bariatric surgery in relation to glucose concentration. Research Methods and Procedures: Visfatin and leptin were studied in 53 SO persons (BMI, 54.4 ± 6.8 kg/m2) before and 7 months after bariatric surgery and in 28 healthy persons (BMI, 26.8 ± 3.8 kg/m2). All of the patients underwent bariatric surgery with biliopancreatic diversion or gastric bypass. Results: The pre‐surgery levels of visfatin in the SO group were greater than in the control group (55.9 ± 39.9 vs. 42.9 ± 16.6 ng/mL, p = 0.024). This increase was significant in the SO group with impaired fasting glucose (63.4 ± 36.6 ng/mL) and diabetes (60.0 ± 46.0 ng/mL). SO patients with normal fasting glucose had similar levels of visfatin to the controls. Seven months after surgery, visfatin levels were significantly increased (84.8 ± 32.8 ng/mL, p < 0.001). This increase was independent of the pre‐surgical glucose levels. The type of bariatric surgery had no influence on visfatin levels. Post‐surgical visfatin was significantly correlated with the post‐surgery plasma concentrations of leptin (r = 0.39, p = 0.014). Discussion: Plasma levels of visfatin in the SO group were increased but only when accompanied by high glucose levels, even in the range of impaired fasting glucose. Bariatric surgery causes an increase in visfatin, which is correlated mainly with the changes produced in the leptin concentration. 相似文献
139.
Han SK Federico S Grillo A Giaquinta G Herzog W 《Biomechanics and modeling in mechanobiology》2007,6(3):139-150
The integrity of articular cartilage depends on the proper functioning and mechanical stimulation of chondrocytes, the cells
that synthesize extracellular matrix and maintain tissue health. The biosynthetic activity of chondrocytes is influenced by
genetic factors, environmental influences, extracellular matrix composition, and mechanical factors. The mechanical environment
of chondrocytes is believed to be an important determinant for joint health, and chondrocyte deformation in response to mechanical
loading is speculated to be an important regulator of metabolic activity. In previous studies of chondrocyte deformation,
articular cartilage was described as a biphasic material consisting of a homogeneous, isotropic, linearly elastic solid phase,
and an inviscid fluid phase. However, articular cartilage is known to be anisotropic and inhomogeneous across its depth. Therefore,
isotropic and homogeneous models cannot make appropriate predictions for tissue and cell stresses and strains. Here, we modelled
articular cartilage as a transversely isotropic, inhomogeneous (TI) material in which the anisotropy and inhomogeneity arose
naturally from the microstructure of the depth-dependent collagen fibril orientation and volumetric fraction, as well as the
chondrocyte shape and volumetric fraction. The purpose of this study was to analyse the deformation behaviour of chondrocytes
using the TI model of articular cartilage. In order to evaluate our model against experimental results, we simulated indentation
and unconfined compression tests for nominal compressions of 15%. Chondrocyte deformations were analysed as a function of
location within the tissue. The TI model predicted a non-uniform behaviour across tissue depth: in indentation testing, cell
height decreased by 43% in the superficial zone and between 11 and 29% in the deep zone. In unconfined compression testing,
cell height decreased by 32% in the superficial zone, 25% in the middle, and 18% in the deep zones. This predicted non-uniformity
is in agreement with experimental studies. The novelty of this study is the use of a cartilage material model accounting for
the intrinsic inhomogeneity and anisotropy of cartilage caused by its microstructure. 相似文献
140.