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101.
Maria João Feio Trefor B. Reynoldson Verónica Ferreira Manuel Augusto S. Graça 《Hydrobiologia》2007,579(1):55-68
We sampled macroinvertebrates at 75 locations in the Mondego river catchment, Central Portugal, and developed a predictive
model for water quality assessment of this basin, based on the Reference Condition Approach. Sampling was done from June to
September 2001. Fifty-five sites were identified as “Reference sites” and 20 sites were used as “Test sites” to test the model.
At each site we also measured 40 habitat variables to characterize water physics and chemistry, habitat type, land use, stream
hydrology and geographic location. Macroinvertebrates were generally identified to species or genus level; a total of 207
taxa were found. By Unweighted Pair Group Method with Arithmetic mean (UPGMA) clustering and analysis of species contribution
to similarities percentage (SIMPER), two groups of reference sites were established. Using Discriminant Analysis (stepwise
forward), four variables correctly predicted 78% of the reference sites to the appropriate group: stream order, pool quality,
substrate quality and current velocity. Test sites’ environmental quality was established from their relative distance to
reference sites, in MDS ordination space, using a series of bands (BEAST methodology). The model performed well at upstream
sites, but at downstream sites it was compromised by the lack of reference sites. As with the English RIVPACS predictive model,
the Mondego model should be continually improved with the addition of new reference sites. The adaptation of the Mondego model
methodology to the Water Framework Directive is possible and would consist mainly of the integration of the WFD typology and
increasing the number of ellipses that define quality bands.
Handling editor: K. Martens 相似文献
102.
Sacramento Doralice Rodrigues Coelho Rosalie Reed Rodrigues Wigg Márcia Dutra Toledo Luna Linhares Luiz Fernando de Matos dos Santos Marta Gonçalves Azevedo Soares Semêdo Luzia Teixeira de Ribeiro da Silva Antonio Jorge 《World journal of microbiology & biotechnology》2004,20(3):225-229
A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial
activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions,
obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic
fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type
1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
103.
Jesús Olivero John E. Fa Miguel A. Farfán Jerome Lewis Barry Hewlett Thomas Breuer Giuseppe M. Carpaneto María Fernández Francesco Germi Shiho Hattori Josephine Head Mitsuo Ichikawa Koichi Kitanaishi Jessica Knights Naoki Matsuura Andrea Migliano Barbara Nese Andrew Noss Dieudonné Ongbwa Ekoumou Pascale Paulin Raimundo Real Mike Riddell Edward G. J. Stevenson Mikako Toda J. Mario Vargas Hirokazu Yasuoka Robert Nasi 《PloS one》2016,11(1)
Pygmy populations occupy a vast territory extending west-to-east along the central African belt from the Congo Basin to Lake Victoria. However, their numbers and actual distribution is not known precisely. Here, we undertake this task by using locational data and population sizes for an unprecedented number of known Pygmy camps and settlements (n = 654) in five of the nine countries where currently distributed. With these data we develop spatial distribution models based on the favourability function, which distinguish areas with favourable environmental conditions from those less suitable for Pygmy presence. Highly favourable areas were significantly explained by presence of tropical forests, and by lower human pressure variables. For documented Pygmy settlements, we use the relationship between observed population sizes and predicted favourability values to estimate the total Pygmy population throughout Central Africa. We estimate that around 920,000 Pygmies (over 60% in DRC) is possible within favourable forest areas in Central Africa. We argue that fragmentation of the existing Pygmy populations, alongside pressure from extractive industries and sometimes conflict with conservation areas, endanger their future. There is an urgent need to inform policies that can mitigate against future external threats to these indigenous peoples’ culture and lifestyles. 相似文献
104.
Frank Rasche Ester Marco-Noales Henk Velvis Leo S. van Overbeek María M. López Jan D. van Elsas Angela Sessitsch 《Plant and Soil》2006,289(1-2):123-140
Genetically modified potatoes expressing antibacterial protein T4 lysozyme may offer effective control strategies for bacterial pathogens causing severe potato diseases. Apart from this beneficial effect, it is very important to investigate such engineered potatoes carefully for potential adverse effects on potato-associated bacteria which frequently exhibit plant beneficial functions such as plant growth promotion and antagonism towards pathogens invading the plant. Two field experiments were carried out in Spain to analyze the potential effects of conventional and genetically modified T4-lysozyme producing potatoes on shoot-associated bacteria. The first baseline field trial 2002 was performed in Meliana in which three conventional potato lines, Achirana Inta, Desirée, and Merkur, were cultivated and sampled at flowering. The second field trial was conducted in Cella in 2003 in order to compare the effects of a senescent transgenic, T4 lysozyme expressing potato trait, Desirée DL 12, with its isogenic, non-transformed parental line Desirée. Structural characteristics of potato shoot-associated bacteria was assayed by 16S rRNA-based terminal restriction fragment length polymorphism (T-RFLP) analysis and dominant community members within T-RFLP profiles were identified by sequence analysis of generated 16S rRNA gene libraries. Cultivable bacteria isolated from shoots of potatoes grown in the Meliana field trial were monitored for antibiosis against Ralstonia solanacearum, whereas isolates derived from shoots of potatoes cultivated in the Cella trial were screened for antagonism against Ralstonia solanacearum and Rhizoctonia solani, and for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase production. Determined antagonists were identified by 16S rRNA gene analysis. All potato traits hosted a cultivar-specific community of bacteria with antagonism against the pathogens and/or potential to produce ACC deaminase. Several antagonists obtained from the Cella field potatoes were also observed as ACC deaminase producers. Community profiling revealed a greater diversity differentiation between the senescent T4 lysozyme expressing and parental Desirée lines grown in the Cella field as compared to the variations between the three flowering conventional lines cultivated in the Meliana field trial. Effects of the two varying field sites and different vegetation stages were greater than those of T4 lysozyme when investigating the community composition of bacteria colonizing the shoots of the Desirée line cultivated in both field trials. 相似文献
105.
Mariella Si?a Rachel C. Wood Enrique Saldarriaga Joshua Lawler Joseph Zunt Patricia Garcia César Cárcamo 《PloS one》2016,11(1)
Climate change poses multiple risks to the population of Lima, the largest city and capital of Peru, located on the Pacific coast in a desert ecosystem. These risks include increased water scarcity, increased heat, and the introduction and emergence of vector-borne and other climate sensitive diseases. To respond to these threats, it is necessary for the government, at every level, to adopt more mitigation and adaptation strategies. Here, focus groups were conducted with representatives from five Lima municipalities to determine priorities, perception of climate change, and decision-making processes for implementing projects within each municipality. These factors can affect the ability and desire of a community to implement climate change adaptation and mitigation strategies. The results show that climate change and other environmental factors are of relatively low priority, whereas public safety and water and sanitation services are of highest concern. Perhaps most importantly, climate change is not well understood among the municipalities. Participants had trouble distinguishing climate change from other environmental issues and did not fully understand its causes and effects. Greater understanding of what climate change is and why it is important is necessary for it to become a priority for the municipalities. Different aspects of increased climate change awareness seem to be connected to having experienced extreme weather events, whether related or not to climate change, and to higher socioeconomic status. 相似文献
106.
Begoña Carrasco Cristina Cañas Gary J. Sharples Silvia Ayora 《Journal of molecular biology》2009,390(1):1-49
The RecU Holliday junction (HJ)-resolving enzyme is highly conserved in the Firmicutes phylum of bacteria. In Bacillus subtilis, the recU gene has two putative initiation codons, at positions 1 and 33. In rec+ cells, only the full-length RecU polypeptide (206 residues, 23.9 kDa) was detected even after different stress treatments. To address the relevance of the flexible N-terminus, we constructed mutant variants. Experiments in vivo revealed that recUΔ1-32 (which initiates at Met33 and encodes RecUΔ1-32) and recU31 (the conserved Arg31 residue was substituted with alanine to give RecUR31A) are genuine RecU mutants, rendering cells impaired in DNA repair and chromosomal segregation. RecU has three activities: It (i) cleaves HJs, (ii) anneals complementary strands and (iii) modulates RecA activities. RecUR31A binds and cleaves HJ DNA in vitro as efficiently as wild-type RecU, but RuvB·ATPγS·Mg2+ fails to stimulate the RecUR31A cleavage reaction. In contrast, RecUΔ1-32 forms unstable complexes with DNA and fails to cleave HJs. RecU and its variants are capable of promoting DNA strand annealing and exert a negative effect on deoxy-ATP-dependent RecA-mediated DNA strand exchange. This study shows that the flexible N-terminus of RecU is essential for protein activity. 相似文献
107.
108.
109.
Johara Boldrini-França Renata Santos Rodrigues Ludier Kesser Santos-Silva Dayane Lorena Naves de Souza Mário Sérgio Rocha Gomes Camila Takeno Cologna Edwin de Pauw Loïc Quinton Flávio Henrique-Silva Veridiana de Melo Rodrigues Eliane Candiani Arantes 《Applied microbiology and biotechnology》2015,99(23):9971-9986
110.
CNDO/II calculations of chlorophylls a and b and their beryllium homologs show that the 3d atomic orbitals of the metal atoms contribute significantly to the σ and π bonding energies. In both chlorophylls a and b replacement of magnesium by beryllium stabilizes the total molecular energy by 40 kcal/mol. 相似文献