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21.
Mariana Mayer-Pinto Barbara L. Ignacio Maria T. M. Széchy Mariana S. Viana Maria P. Curbelo-Fernandez Helena P. Lavrado Andrea O. R. Junqueira Eduardo Vilanova Sérgio H. G. Silva 《PloS one》2012,7(10)
Several approaches have been proposed to assess impacts on natural assemblages. Ideally, the potentially impacted site and multiple reference sites are sampled through time, before and after the impact. Often, however, the lack of information regarding the potential overall impact, the lack of knowledge about the environment in many regions worldwide, budgets constraints and the increasing dimensions of human activities compromise the reliability of the impact assessment. We evaluated the impact, if any, and its extent of a nuclear power plant effluent on sessile epibiota assemblages using a suitable and feasible sampling design with no ‘before’ data and budget and logistic constraints. Assemblages were sampled at multiple times and at increasing distances from the point of the discharge of the effluent. There was a clear and localized effect of the power plant effluent (up to 100 m from the point of the discharge). However, depending on the time of the year, the impact reaches up to 600 m. We found a significantly lower richness of taxa in the Effluent site when compared to other sites. Furthermore, at all times, the variability of assemblages near the discharge was also smaller than in other sites. Although the sampling design used here (in particular the number of replicates) did not allow an unambiguously evaluation of the full extent of the impact in relation to its intensity and temporal variability, the multiple temporal and spatial scales used allowed the detection of some differences in the intensity of the impact, depending on the time of sampling. Our findings greatly contribute to increase the knowledge on the effects of multiple stressors caused by the effluent of a power plant and also have important implications for management strategies and conservation ecology, in general. 相似文献
22.
Cylindrocarpon root rot: multi-gene analysis reveals novel species within the Ilyonectria radicicola species complex 总被引:1,自引:0,他引:1
Ana Cabral Johannes Z. Groenewald Cecília Rego Helena Oliveira Pedro W. Crous 《Mycological Progress》2012,11(3):655-688
Ilyonectria radicicola and its Cylindrocarpon-like anamorph represent a species complex that is commonly associated with root rot disease symptoms on a range of hosts. During the course of this study, several species could be distinguished from I. radicicola sensu stricto based on morphological and culture characteristics. DNA sequence analysis of the partial ??-tubulin, histone H3, translation elongation factor 1-?? and nuclear ribosomal RNA-Internal Transcribed Spacer (nrRNA-ITS) genes were employed to provide further support for the morphological species resolved among 68 isolates associated with root rot disease symptoms. Of the various loci screened, nrRNA-ITS sequences were the least informative, while histone H3 sequences were the most informative, resolving the same number of species as the combined dataset across the four genes. Within the Ilyonectria radicicola species complex, 12 new taxa are delineated occurring on a diverse range of hosts, the most common being Cyclamen, Lilium, Panax, Pseudotsuga, Quercus and Vitis. 相似文献
23.
GS Basarab P Hill CJ Eyermann M Gowravaram H Käck E Osimoni 《Bioorganic & medicinal chemistry letters》2012,22(17):5600-5607
Structure-activity relationships are presented around a series of pyrazolopyrimidinediones that inhibit the growth of Helicobacter pylori by targeting glutamate racemase, an enzyme that provides d-glutamate for the construction of N-acetylglucosamine-N-acetylmuramic acid peptidoglycan subunits assimilated into the bacterial cell wall. Substituents on the inhibitor scaffold were varied to optimize target potency, antibacterial activity and in vivo pharmacokinetic stability. By incorporating an imidazole ring at the 7-position of scaffold, high target potency was achieved due to a hydrogen bonding network that occurs between the 3-position nitrogen atom, a bridging water molecule and the side chains Ser152 and Trp244 of the enzyme. The lipophilicity of the scaffold series proved important for expression of antibacterial activity. Clearances in vitro and in vivo were monitored to identify compounds with improved plasma stability. The basicity of the imidazole may contribute to increased aqueous solubility at lower pH allowing for improved oral bioavailability. 相似文献
24.
Helena Geys Geert Molenberghs Lieven Declerck Louise Ryan 《Biometrical journal. Biometrische Zeitschrift》2000,42(3):279-302
Risk assessment for developmental toxicity studies in rodents is faced with the fairly involved data structure of clustered multivariate binary outcomes. While likelihood methods for this setting do not abound, we show that a conditional model, combined with pseudo‐likelihood inference and fractional polynomial predictor functions, as proposed by Royston and Altman (1994), are a promising way forward. The methods are illustrated using teratology data collected under the National Toxicology Program. 相似文献
25.
Pinto LM Pereira R de Paula E de Nucci G Santana MH Donato JL 《Journal of liposome research》2004,14(1-2):51-59
We assessed the effect of local anesthetics (LA) from different families such as esters (benzocaine), linear aminoamides (lidocaine) and cyclic aminoamides (bupivacaine) on the platelet aggregation induced by ADP. Liposomal formulations of the three LA, prepared with egg phosphatidylcholine:cholesterol alpha-tocopherol, were also tested. The three LA were able to inhibit platelet aggregation induced by ADP, in the following order: bupivacaine > lidocaine > benzocaine. After encapsulation into liposomes the inhibitory effect increased for all anesthetics studied, showing that aggregation tests could be used to assess the toxicity of new drug formulations. 相似文献
26.
Sánchez-Magraner L Viguera AR García-Pacios M Garcillán MP Arrondo JL de la Cruz F Goñi FM Ostolaza H 《The Journal of biological chemistry》2007,282(16):11827-11835
alpha-Hemolysin (HlyA) from Escherichia coli is a protein toxin (1024 amino acids) that targets eukaryotic cell membranes, causing loss of the permeability barrier. HlyA consists of two main regions, an N-terminal domain rich in amphipathic helices, and a C-terminal Ca(2+)-binding domain containing a Gly- and Asp-rich nonapeptide repeated in tandem 11-17 times. The latter is called the RTX domain and gives its name to the RTX protein family. It had been commonly assumed that membrane interaction occurred mainly if not exclusively through the amphipathic helix domain. However, we have cloned and expressed the C-terminal region of HlyA, containing the RTX domain plus a few stabilizing sequences, and found that it is a potent surface-active molecule. The isolated domain binds Ca(2+) with about the same affinity (apparent K(0.5) approximately 150 microM) as the parent protein HlyA, and Ca(2+) binding induces in turn a more compact folding with an increased proportion of beta-sheet structure. Both with and without Ca(2+) the C-terminal region of HlyA can interact with lipid monolayers spread at an air-water interface. However, the C-terminal domain by itself is devoid of membrane lytic properties. The present results can be interpreted in the light of our previous studies that involved in receptor binding a peptide in the C-terminal region of HlyA. We had also shown experimentally the distinction between reversible membrane adsorption and irreversible lytic insertion of the toxin. In this context, the present data allow us to propose that both major domains of HlyA are directly involved in membrane-toxin interaction, the nonapeptide repeat, calcium-binding RTX domain being responsible for the early stages of HlyA docking to the target membrane. 相似文献
27.
Natácia Evangelista de Lima Alexandre Assis Carvalho Alan William Meerow Maura Helena Manfrin 《Organisms Diversity & Evolution》2018,18(2):151-161
The genus Acrocomia, popularly known as macaw palm or macaúba, occurs in savanna areas and open forests of tropical America, with distribution from Central to southern South America. They are important oleaginous palm trees, due to their role in ecosystems and local economies and their potential for biofuel production and vegetable oil. Although the taxonomy of the genus is not resolved because of observed phenotypic diversity in A. aculeata (Jacq.) Lodd. ex Mart., there are several conflicting treatments. Some authors recognize three caulescent spp. occurring in South America: A. aculeata, A. intumescens Drude, and A. totai Mart, although a new one was described recently—Acrocomia corumbaensis. Because some Latin American governments want to expand production of macaw palm in their territory as raw material for agro-energy, several groups have been encouraged to study this genus, focusing on the production of biodiesel, seed germination, phenotypic aspects, and genetic diversity. The goal of this review is to compile key information available in the literature and herbarium data, focusing on South American populations of the genus. 相似文献
28.
29.
Christian G. Ramos André M. Grilo Sílvia A. Sousa Marta L. Barbosa Helena Nadais Jorge H. Leitão 《Applied microbiology and biotechnology》2010,85(3):801-806
This work describes a methodology combining DNA extraction, polymerase chain reaction amplification with primers targeting 16S ribosomal RNA genes, cloning, and sequencing of clones previously analyzed by restriction fragment length polymorphism (RFLP), which can be applied to study the microbial diversity in a given habitat. The methodology allows the minimization of the sequencing effort, which is particularly relevant when analyzing large numbers of clones. The methodology does not require particularly skilled personnel and can easily be adaptable to the molecular characterization of virtually any particular microbial population, provided that both adequate primers and suitable restriction enzymes for RFLP analysis of the clone library have been chosen. An example of application is presented, in which a sample taken from a continuously operating upflow anaerobic sludge blanket reactor was analyzed. RFLP analysis of the initial 162 clones with HaeIII allowed the identification of only 28 distinct profiles. As expected, identical RFLP profiles corresponded to identical nucleotide sequences. 相似文献
30.