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81.
Direct infusion ESI‐IT‐MSn alkaloid profile and isolation of tetrahydroharman and other alkaloids from Bocageopsis pleiosperma maas (Annonaceae) 下载免费PDF全文
82.
Phylogenetic eigenvectors and nonstationarity in the evolution of theropod dinosaur skulls 下载免费PDF全文
J. A. F. Diniz‐Filho D. M. C. C. Alves F. Villalobos M. Sakamoto S. L. Brusatte L. M. Bini 《Journal of evolutionary biology》2015,28(7):1410-1416
Despite the long‐standing interest in nonstationarity of both phenotypic evolution and diversification rates, only recently have methods been developed to study this property. Here, we propose a methodological expansion of the phylogenetic signal‐representation (PSR) curve based on phylogenetic eigenvectors to test for nonstationarity. The PSR curve is built by plotting the coefficients of determination R2 from phylogenetic eigenvector regression (PVR) models increasing the number of phylogenetic eigenvectors against the accumulated eigenvalues. The PSR curve is linear under a stationary model of trait evolution (i.e. the Brownian motion model). Here we describe the distribution of shifts in the models R2 and used a randomization procedure to compare observed and simulated shifts along the PSR curve, which allowed detecting nonstationarity in trait evolution. As an applied example, we show that the main evolutionary pattern of variation in the theropod dinosaur skull was nonstationary, with a significant shift in evolutionary rates in derived oviraptorosaurs, an aberrant group of mostly toothless, crested, birdlike theropods. This result is also supported by a recently proposed Bayesian‐based method (AUTEUR). A significant deviation between Ceratosaurus and Limusaurus terminal branches was also detected. We purport that our new approach is a valuable tool for evolutionary biologists, owing to its simplicity, flexibility and comprehensiveness. 相似文献
83.
Differential effects of temperature change and human impact on European Late Quaternary mammalian extinctions 下载免费PDF全文
Sara Varela Matheus Souza Lima‐Ribeiro JosÉ Alexandre Felizola Diniz‐Filho David Storch 《Global Change Biology》2015,21(4):1475-1481
Species that inhabited Europe during the Late Quaternary were impacted by temperature changes and early humans, resulting in the disappearance of half of the European large mammals. However, quantifying the relative importance that each factor had in the extinction risk of species has been challenging, mostly due to the spatio‐temporal biases of fossil records, which complicate the calibration of realistic and accurate ecological niche modeling. Here, we overcome this problem by using ecotypes, and not real species, to run our models. We created 40 ecotypes with different temperature requirements (mean temperature from ?20 °C to 25 °C and temperature range from 10 °C to 40 °C) and used them to quantify the effect of climate change and human impact. Our results show that cold‐adapted ecotypes would have been highly affected by past temperature changes in Europe, whereas temperate and warm‐adapted ecotypes would have been positively affected by temperature change. Human impact affected all ecotypes negatively, and temperate ecotypes suffered the greatest impacts. Based on these results, the extinction of cold‐adapted species like Mammuthus primigenius may be related to temperature change, while the extinction of temperate species, like Crocuta crocuta, may be related to human impact. Our results suggest that temperature change and human impact affected different ecotypes in distinct ways, and that the interaction of both impacts may have shaped species extinctions in Europe. 相似文献
84.
José Alexandre Felizola Diniz Filho Fabricio Villalobos Luis Mauricio Bini 《Genetics and molecular biology》2015,38(3):396-400
Eigenfunction analyses have been widely used to model patterns of autocorrelation in time, space and phylogeny. In a phylogenetic context, Diniz-Filho et al. (1998) proposed what they called Phylogenetic Eigenvector Regression (PVR), in which pairwise phylogenetic distances among species are submitted to a Principal Coordinate Analysis, and eigenvectors are then used as explanatory variables in regression, correlation or ANOVAs. More recently, a new approach called Phylogenetic Eigenvector Mapping (PEM) was proposed, with the main advantage of explicitly incorporating a model-based warping in phylogenetic distance in which an Ornstein-Uhlenbeck (O-U) process is fitted to data before eigenvector extraction. Here we compared PVR and PEM in respect to estimated phylogenetic signal, correlated evolution under alternative evolutionary models and phylogenetic imputation, using simulated data. Despite similarity between the two approaches, PEM has a slightly higher prediction ability and is more general than the original PVR. Even so, in a conceptual sense, PEM may provide a technique in the best of both worlds, combining the flexibility of data-driven and empirical eigenfunction analyses and the sounding insights provided by evolutionary models well known in comparative analyses. 相似文献
85.
Renan de Souza Rezende Gustavo Figueiredo Marques Leite Anderson Kennedy Soares De‐Lima Luis Antonio Braga Da Silva Filho Camila Vilarinho Costa Chaves Ana Cecilia Holler Prette June Spriger Freitas José Francisco Gonçalves Júnior 《Austral ecology》2015,40(6):693-700
The allochthonous detritus that accumulates in the substrate of streams is used by aquatic invertebrate shredders for shelter and food. Shredders are considered rare in tropical systems, and little information is available about the role of density effects and predation risk (associated with the perception of predators by prey) in relationship to the resources used by these organisms. The aim of this study was to examine experimentally the effects of increased predation risk and of the density of Phylloicus sp. (i.e. of two types of biological relationships) on the processing of the leaf litter of Nectandra megapotamica (Spreng.) Mez. Phylloicus sp. can use leaf litter for case building and as a food resource. The density effect was measured using four treatments that differed only in the number of individuals (one, two, three or four). A second experiment with five treatments was performed to test the risk of non‐lethal predation on detritus consumption (shelter and food) by Phylloicus sp. (T1: Caddisfly; T2: Mayfly; T3: Astyanax sp./fish; T4: Damselflies; T5: Stonefly). A single Phylloicus and one other organism (a potential predator blocked with 0.5 mm fine mesh) were placed in each tank (0.002 m3 volume). We observed a negative effect of density on per capita litter consumption (experiment 1). The low density of Phylloicus may be a natural factor that decreases intraspecific competition. In the presence of fish, Phylloicus showed the lowest amount of litter processing observed in the experiment, indicating top‐down control (experiment 2). In treatments that involved the presence of invertebrates (non‐predatory and predatory), Phylloicus showed the highest amount and an intermediate amount of leaf litter processing, respectively (experiment 2). This observation also suggests that the predation effect is more probable for specific predator–prey pairs. Population density and predation risk in Phylloicus may be important factors controlling leaf litter processing. 相似文献
86.
Nelo Eidy Zanchi Frederico Gerlinger-Romero Lucas Guimarães-Ferreira Mário Alves de Siqueira Filho Vitor Felitti Fabio Santos Lira Marília Seelaender Antonio Herbert LanchaJr. 《Amino acids》2011,40(4):1015-1025
Amino acids such as leucine and its metabolite α-ketoisocaproate (KIC), are returning to be the focus of studies, mainly because
of their anti-catabolic properties, through inhibition of muscle proteolysis and enhancement of protein synthesis. It is clear
that these effects may counteract catabolic conditions, as well as enhance skeletal muscle mass and strength in athletes.
Moreover, beta-hydroxy-beta-methylbutyrate (HMB) has been shown to produce an important effect in reducing muscle damage induced
by mechanical stimuli of skeletal muscle. This review aims to describe the general scientific evidence of KIC and HMB supplementation
clinical relevance, as well as their effects (e.g., increases in skeletal muscle mass and/or strength), associated with resistance
training or other sports. Moreover, the possible mechanisms of cell signaling regulation leading to increases and/or sparing
(during catabolic conditions) of skeletal muscle mass are discussed in detail based on the recent literature. 相似文献
87.
Use of experimental design to investigate biodiesel production by multiple-stage Ultra-Shear reactor
Da Silva Nde L Garnica JA Batistella CB Maciel MR Maciel Filho R 《Bioresource technology》2011,102(3):2672-2677
This work presents biodiesel production from soybean oil and bioethanol by multiple-stage Ultra-Shear reactor (USR). The experiments were carried out in the following conditions: reaction time from 6 to 12 min; catalyst concentration from 0.5% to 1.5% by weight of soybean oil; ethanol: soybean oil molar ratio from 6:1 to 10:1. The experimental design was used to investigate the influence of process variables on the conversion in biodiesel. The best ethyl ester conversion obtained was 99.26 wt.%, with ethanol:soybean oil molar ratio of 6:1, catalyst concentration of 1.35% and with 12 min of reaction time. 相似文献
88.
Analysis of the NAC transcription factor gene family in citrus reveals a novel member involved in multiple abiotic stress responses 总被引:1,自引:0,他引:1
89.
Carolina A. Lima José L. Lima Filho Benício B. Neto Attilio Converti Maria G. Carneiro da Cunha Ana L. F. Porto 《Biotechnology and Bioprocess Engineering》2011,16(3):549-560
A 24 full factorial design was used to identify the main effects and interactions of the initial medium pH, soybean flour concentration,
temperature and orbital agitation speed on extracellular collagenase production by Penicillium aurantiogriseum URM4622. The most significant variables for collagenase production were soybean flour concentration and initial medium pH
that had positive main effects, and temperature that had a negative one. Protein concentration in soybean flour revealed to
be a significant factor for the production of a collagenase serine proteinase. The most favorable production conditions were
found to be 0.75% soybean flour, pH 8.0, 200 rpm, and 28°C, which led to a collagenase activity of 164 U. The enzyme showed
an optimum activity at 37°C and pH 9.0, was stable over wide ranges of pH and temperature (6.0 ∼ 10.0 and 25 ∼ 45°C, respectively)
and was strongly inhibited by 10 mM phenylmethylsulphonylfluoride. The firstorder rate constants for collagenase inactivation
in the crude extract, calculated from semi-log plots of the residual activity versus time, were used in Arrhenius and Eyring
plots to estimate the main thermodynamic parameters of thermoinactivation (E*
d
= 107.4 kJ/mol and ΔH*
d
= 104.7 kJ/mol). The enzyme is probably an extracellular neutral serine collagenase effective on azocoll, gelatin and collagen
decomposition. 相似文献
90.
Marina O. S. Dias Marcelo Pereira da Cunha Rubens Maciel Filho Antonio Bonomi Charles D. F. Jesus Carlos E. V. Rossell 《Journal of industrial microbiology & biotechnology》2011,38(8):955-966
Sugarcane bagasse is used as a fuel in conventional bioethanol production, providing heat and power for the plant; therefore,
the amount of surplus bagasse available for use as raw material for second generation bioethanol production is related to
the energy consumption of the bioethanol production process. Pentoses and lignin, byproducts of the second generation bioethanol
production process, may be used as fuels, increasing the amount of surplus bagasse. In this work, simulations of the integrated
bioethanol production process from sugarcane, surplus bagasse and trash were carried out. Selected pre-treatment methods followed,
or not, by a delignification step were evaluated. The amount of lignocellulosic materials available for hydrolysis in each
configuration was calculated assuming that 50% of sugarcane trash is recovered from the field. An economic risk analysis was
carried out; the best results for the integrated first and second generation ethanol production process were obtained for
steam explosion pretreatment, high solids loading for hydrolysis and 24–48 h hydrolysis. The second generation ethanol production
process must be improved (e.g., decreasing required investment, improving yields and developing pentose fermentation to ethanol)
in order for the integrated process to be more economically competitive. 相似文献