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981.
Rodríguez-Bonilla P López-Nicolás JM Méndez-Cazorla L García-Carmona F 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(15-16):1091-1097
In this work, a reversed phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of pterostilbene in food samples. The novel method is based on the addition of cyclodextrins (CDs) to the mobile phase where the complexation of pterostilbene by CDs is carried out. In order to select the most suitable conditions for the RP-HPLC method, the effect of several physico-chemical parameters on the complexation of pterostilbene by CDs was studied. Our results show that the addition of 12 mM HP-β-CD to a 50:50 (v/v) methanol:water mobile phase at 25°C and pH 7.0 significantly improves the main analytical parameters. In addition, it was seen that pterostilbene forms a 1:1 complex with HP-β-CD, showing an apparent complexation constant of 251±13 M(-1). Finally, in order to study the validity of the proposed method, blueberries were analyzed and the concentration of pterostilbene has been determined. 相似文献
982.
983.
Galofré JC Gómez-Sáez JM álvarez Escola C álvarez García E Anda Api?aniz E Calleja A Donnay S Lucas-Martin A Menéndez Torre E Navarro González E Pereg V Pérez Corral B Santamaría Sandi J Riesco Eizaguirre G Zafón Llopis C;Toma de posición del Grupo de Trabajo de Cáncer de Tiroides de la Sociedad Espa?ola de Endocrinología y Nutrición 《Endocrinología y nutrición》2011,58(8):381-386
984.
985.
Gracia P. González-Porter Frank Hailer Oscar Flores-Villela Rony García-Anleu Jesús E. Maldonado 《Conservation Genetics》2011,12(5):1229-1242
We conducted a phylogeographic analysis of the strictly aquatic and critically endangered Central American river turtle, Dermatemys mawii, as part of a conservation management program for the species. We sampled 238 individuals from 15 different localities throughout
the species range. Using sequence fragments from the mtDNA Cyt b and ND4 genes, we identified 16 different haplotypes. Overall, our results reveal a signal of phylogeographic structure throughout
the range, which appears to have been secondarily blurred by extensive gene flow. Notably, this also applies to genetic structuring
across three major hydrological basins that pose biogeographic breaks in other aquatic taxa. Divergence times of mtDNA haplotypes
in D. mawii suggest that the main lineages split in the Pliocene–Pleistocene (3.73–0.227 MA) and demographic tests indicate that the
species has undergone drastic demographic size fluctuations since this time period. One ancient haplotype (1D) was found to
exhibit sequence divergence of up to 2% from other haplogroups. Divergence of this magnitude is indicative of species level
differentiation in other turtle genera. Haplotype 1D was found in only two localities, Sarstun and Salinas, but specimens
with other haplotypes were also found in those localities. It is not known whether the individuals with the 1D haplotype interbreed
with non-1D individuals. Our results suggest that human activity, such as harvesting and long distance transport of animals,
may have influenced the current patterns of genetic diversity. For more than 2000 years, D. mawii has been consumed by people from Middle American cultures, and the archeological record contains strong evidence that the
Mayans transported animals between villages and far away from their natural distribution range. Therefore, the large-scale
pattern of haplotype sharing even across hydrological barriers, the observed low haplotype diversity in some populations and
the contemporary absence of a pronounced phylogeographic pattern is likely due to a combination of population expansions,
gene flow, extensive human-mediated-movements and recent bottlenecks resulting from over-harvesting. 相似文献
986.
Johel Chaves-Campos Steven G. Johnson Francisco J. Garc��a de Le��n C. Darrin Hulsey 《Conservation Genetics》2011,12(2):557-567
The valley of Cuatro Ciénegas in Mexico has the highest degree of local endemicity of any habitat in North America. A large number of endemic aquatic species occur both in the Cuatro Ciénegas basin and in the upper parts of the Río Salado de los Nadadores drainage, located immediately to the east of the valley. No natural surface flow occurs between these basins but artificial canals connect both areas. It is not clear whether the sharing of endemics between the Cuatro Ciénegas basin and the Río Salado is due to migration through canals. We conducted a phylogeographic study of mitochondrial haplotypes of the endemic shrimp Palaemonetes suttkusi to determine the evolutionary distinctiveness of the population found in Río Salado. We discovered that P. suttkusi likely has occurred naturally in both basins well into the distant past. Based on molecular clock analyses of the COI gene, the populations in the Río Salado and much of the Cuatro Ciénegas basin likely began diverging from each other between 1.9 and 11.2 Myr ago. The general levels of divergence are substantial but our results suggest there has also likely been recent gene flow between these basins. This is consistent with migration through human-made canals, but also consistent with the occurrence of natural gene flow during intermittent wet periods in the past million years. We also found significant differentiation of the Pozas Azules area from the rest of the Cuatro Ciénegas basin, a finding that is concordant with several phylogeographic studies on other aquatic endemics in Cuatro Ciénegas. We recommend that the upper parts of the Río Salado, the Pozas Azules area, and the rest of the Cuatro Ciénegas basin should each be considered independent evolutionarily significant units for conservation, and that migration of species through human-made canals should be monitored and controlled. 相似文献
987.
988.
989.
Rivera-Pérez C del Toro Mde L García-Carreño F 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2011,158(1):99-105
An intracellular lipase present in the whiteleg shrimp Litopenaeus vannamei was detected in pleopods. The lipase from pleopods was purified and characterized by biochemical and kinetic parameters. Purified intracellular lipase has a molecular mass of 196kDa, the polypeptide is assembled by two monomers, 95.26 and 63.36kDa. The enzyme lacks glycosylation, and it has an isoelectric point of 5.0. The enzyme showed the highest activity at a temperature range of 30-40°C at pH 8.0-10.0. Activity was completely inhibited by tetrahydrolipstatin and diethyl p-nitrophenyl phosphate, suggesting that the intracellular lipase is a serine lipase. The lipase hydrolyzes short and long-chain triacylglycerides, as well as naphthol derivatives at comparable rates in contrast to other sources of lipases. Specific activity of 930U mg(-1) and 416.56U mg(-1) was measured using triolein and tristearin at pH 8.0 at 30°C as substrates, respectively. The lipase showed a K(M,app) of 41.03mM and k(cat)/K(M,app) ratio of 4.88 using MUF-butyrate as the substrate. The intracellular lipase described for shrimp has a potential role in hydrolysis of triacylglycerides stored as fat body, as has been shown in humans. 相似文献
990.
Cristina Aponte Luis V. García Ignacio M. Pérez‐Ramos Eduardo Gutiérrez Teodoro Marañón 《植被学杂志》2011,22(5):856-867
Questions: What is the spectrum of variability of chemical elements in a Mediterranean forest ecosystem across the different compartments? Do co‐existing tree species with different leaf chemical composition and nutrient cycling distinctly modify soil conditions? Could these species‐specific, tree‐generated soil changes create a potential positive feedback by affecting long‐term species distribution? Location: Mixed oak forests of southern Spain, Los Alcornocales Natural Park. Methods: We sampled and chemically analysed five different ecosystem components: leaves, leaf fall, litter and superficial (0–25 cm) and sub‐superficial (25–50 cm) soil beneath the canopies of evergreen Quercus suber and deciduous Q. canariensis trees. We used multiple co‐inertia analysis (MCoA) to conjointly analyse the patterns of variability and covariation of eight macro‐ and micronutrients determined in each of the sampled ecological materials. We implemented a path analysis to investigate alternative causal models of relationships among the chemical properties of the different ecosystem components. Results: Variability in the concentration of chemical elements was related to the nature of their biogeochemical cycles. However, the rank of element concentration was consistent across ecosystem components. Analysis of co‐inertia (MCoA) revealed that there was a common underlying multivariate pattern of nutrient enrichment in the ecosystem, which supported the hypothesis of a separation in biogeochemical niches between the two co‐existing oak species, with Q. canariensis having richer plant tissues and more fertile soil directly under each tree than Q. suber. The feasibility of a potential tree–soil positive feedback model was the only statistically validated among several alternative (non‐feedback) models tested. Conclusions: In the studied Mediterranean forests, oak species distinctly modify soil fertility conditions through different nutrient return pathways. Further investigation is needed to address whether these tree‐generated soil changes could affect seedling establishment and ultimately influence species distribution. 相似文献