Browsing by Author "Santos, C."
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- Data report: IODP Expedition 339 Site U1391: an improved splice and preliminary age model on the basis of XRF dataPublication . Abrantes, Fatima; Santos, C.; Ventura, C.; Voelker, Antje; Röhl, U.; Stow, Dorrik A. V.; Hernandez-Molina, F. Javier; Alvarez Zarikian, Carlos A.; Expedition 339 ScientistsWith the objective to reconstruct past primary production on the southwest Portuguese margin at orbital and millennial timescales through the Pleistocene, we chose to compare two sites recovered during Expedition 339 at similar latitude but different distances to the coast (Sites U1385 and U1391). Site U1385 has a well-established chronology, but for Site U1391 no isotope data are yet available. In order to develop a correct chronology without isotope data, we performed XRF analysis of cores from Holes U1391A and U1391B between 76.51 and 205.77 mbsf. With these data, in particular using log(Ca/Ti) and log(Ca/Fe), it was possible to enhance the Site U1391 splice and to establish an age model based on the correlation to the well-defined and robust Site U1385 age model.
- Development of an asymmetric PCR-ELISA typing method for citrus tristeza virus based on the coat protein genePublication . Nolasco, Gustavo; Santos, C.; Silva, Goncalo; Fonseca, FilomenaThe coat protein gene of isolates of citrus tristeza virus (CTV) from 20 citrus-producing regions around the world was amplified by RT-PCR, TA cloned, and characterized by SSCP. Haplotypes that produced different patterns within each geographic region were sequenced and a database of 153 accessions of CTV was assembled. Phylogenetic analysis revealed the existence of seven well-defined clusters (Coefficient of differentiation 0.78). An asymmetric PCR-ELISA typing (APET) assay was developed in the frame of this clustering pattern using a set of eight hybridisation probes. The membership of any unknown haplotype is determined by comparing its pattern of reaction against the whole set of probes and not, as previously done in hybridisation assays, in an all-or-nothing basis. Interpretation of the results is objective and done through a visual basic application that compares the rates of hydrolysis of the ELISA substrate of an assayed isolate to a matrix of rates of hydrolysis obtained from standard haplotypes. This assay was validated and showed a better ability to resolve haplotypes than other assays to which it was compared experimentally. It may be automated to the same extent as any ELISA. (c) 2008 Elsevier B.V. All rights reserved.
- First report of Citrus tristeza virus in the State Union of Serbia and Montenegro.Publication . Papic, T.; Santos, C.; Nolasco, GustavoCitrus production in the State Union of Serbia and Montenegro has a strategic importance to the agricultural sector. Approximately 400,000 trees are now grown in the major citrus producing region, which is the Montenegrin Coastal Region. Satsuma mandarins and lemons grafted on Poncirus trifoliata are the most cultivated varieties. In December 2003, eight samples taken from the coastal region close to the towns of Bar and Ulcinj were analyzed using enzyme- linked immunosorbent assay (ELISA) with SP7 antibodies produced at Universidade do Algarve, Portugal (3). Further analysis was done using immunocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) targeting the entire coat protein (CP) gene (forward primer CTV1: 5(prime)- ATGGACGACGAAACAAAGAA-3(prime) and reverse primer CTV10: 5 (prime)-ATCAACGTGTGTTGAATTTCC-3(prime)). Using both techniques, seven of eight samples analyzed were found to be infected by Citrus tristeza virus (CTV), including samples from five trees that exhibited chlorosis, gummosis, and fruit deformation, and two trees that were symptomless.
- Genomic variability of Citrus tristeza virus (CTV) isolates introduced into MoroccoPublication . Lbida, B.; Fonseca, Filomena; Santos, C.; Zemzami, M.; Bennani, A.; Nolasco, GustavoGenomic variability of the coat protein gene of Citrus tristeza virus isolates obtained from old Meyer lemon introductions in Morocco and more recent budwood introductions from Spain were studied. The coat protein gene of the virus was amplified directly from infected tissue by immunocapture RT-PCR and analysed by single stranded conformation polymorphism (SSCP) and sequencing. Each isolate consisted of several related genomic variants, typical of a quasi-species. Although SSCP analysis has only limited typing ability it could be used in an initial screening to discriminate between isolates of different origin and to analyse the genomic structure of each isolate. Sequence analysis showed that the isolates of Spanish origin were closely related to mild isolates characterised in Florida and in Portugal. The Meyer lemon isolate on the other hand was related to severe strains of Meyer lemon characterised in Florida some years ago and to other severe strains from Brasil. A knowledge of the coat protein gene sequence is useful to trace the origin of the isolates.
- Membranes technology used in water treatment: Chemical, microbiological and ecotoxicological analysisPublication . Palma, Patrícia; Fialho, S.; Alvarenga, P.; Santos, C.; Bras, T.; Palma, G.; Cavaco, C.; Gomes, R.; Neves, L. A.The increment of world's Human population, with the consequent demand for water supply, plus the need for sustainable development and the conservation of water resources, highlights the urgency of improving water treatment technologies and management actions.The aim of the present study was to characterize and evaluate the efficiency of nanofiltration (NF90, NF270) and reverse osmosis (SW30) membranes, in improving the quality of three types of waters: irrigation, municipal supply and wastewater. The efficiency of using this technology was assessed by: (i) the study of water permeability and rejection of some chemical parameters, such as total nitrogen, total phosphorus, chemical oxygen demand (COD), biochemical oxygen demand (BOD5), feacal coliforms, nitrates, chlorides, iron and manganese; and (ii) the evaluation of their ecotoxicological effects, through the use of representative species of different taxonomic and functional groups (Vibrio fischeri, Thamnocephalus platyurus, Daphnia magna, and Pseudokirchneriella subcapitata). Results indicated that all three membranes have high rejection percentages for the majority of the studied parameters (>90%). All parameters concentrations in the permeate stream were below the limit values from Portuguese legislation and European Directives. With respect to the ecotoxicological effects, in general, the use of membranes removed the toxicity detected in the initial samples (which exhibited significant toxicity). The SW30 membrane showed a greater efficiency for toxicity removal, comparing with the nanofiltration membranes. Further, among the nanofiltration membranes used, the NF90 promoted a greater decrease in the toxicity of the samples. Thus, treatment with the membranes NF90 and SW30 allowed obtaining waters with high quality and low ecotoxicological potential, without risks for human populations and endangering the environmental balance. (C) 2016 Elsevier B.V. All rights reserved.
- Micropropagation of the Mediterranean species Viburnum tinusPublication . Nobre, J.; Santos, C.; Romano, AnabelaIn vitro propagation of the Mediterranean species Viburnum tinus L. was established from an outdoor-grown shrub. Two standard macrosalt formulations (Margara N30K and Murashige and Skoog), a range of benzyladenine and sucrose concentrations were tested for their effect on shoot multiplication. The cytokinin concentration was the most important factor affecting shoot multiplication. The highest shoot multiplication rate was obtained from single-node explants cultured on Murashige and Skoog medium supplemented with 4.4 mu M benzyladenine. Cytokinin concentration and an interaction of macrosalts and benzyladenine influenced shoot length on the multiplication stage: best shoot growth was observed on MS medium containing 1.1 mu M benzyladenine. In addition, sucrose concentrations of 87.6-146.0 mM gave the highest multiplication rates and improved shoot growth. Following a shoot ellongation stage, single shoots were rooted on media containing naphtaleneacetic acid (1.3-5.4 mu M). Although enhanced in vitro rooting was obtained on media containing 5.4 mu M naphtaleneacetic acid, reducing the auxin concentration to 1.3 mu M during the in vitro rooting stage improved acclimatisation frequency and further plant growth in a horticultural substrate.
- Molecular characterization of Citrus tristeza virus isolates from Cyprus on the basis of the coat protein genePublication . Papayiannis, L. C.; Santos, C.; Kyriakou, A.; Kapari, T.; Nolasco, GustavoWithin the context of a program in Cyprus for the control of Citrus tristeza virus (CTV), the coat protein (CP) genes of 12 local isolates of the virus that induced different symptoms on host trees, were compared to those of known isolates. The CP genes were reverse-transcribed (RT) and amplified by polymerase chain reaction (PCR) and the resulting amplicons were cloned and sequenced. Nucleotide sequence analysis revealed no signs of geographic speciation. All the sequences obtained clustered close to those of previously known isolates of worldwide origin that are in five distinct groups. The nucleotide diversity was high compared to that found using a worldwide database of CP gene sequences. These data support the existence of different CTV introductions into Cyprus or an introduction from a location in which CTV is relatively diverse. Some of the isolates induced stem pitting on branches of grapefruit and sweet orange. Such isolates have not been noted often in the Mediterranean basin. They were close in CP sequence to isolate B249 from Venezuela, which induces stem pitting, and are of particular concern for the whole region.
- Nanofiltration ability to remove copper oxide and silver nanoparticles: The role of surface charge and sizePublication . Serrão Sousa, Vânia; Santos, C.; Ribau Teixeira, Margarida; Marsh, N.This work pretends to study the performance of nanofiltration (NF) membranes in the removal of copper oxide and silver nanoparticles (NPs) and evaluate the role of surface charge and size of the NPs on this performance. Results demonstrate that positive charged CuO NPs are adsorbed onto negatively charged NF membrane, whereas for the negatively charged Ag NPs the adsorption on the membrane surface is much lower. For CuO NPs, NF270 is very efficient and the main mechanism of removal seems to be adsorption. For Ag NPs, removals are low due to the hydrodynamic diameter of the NPs at this pH compared to the membrane cut-off (similar to 170 Da).
- Occurrence of stem-pitting strains of Citrus tristeza virus in CroatiaPublication . Cerni, S.; Skoric, D.; Krajacic, M.; Gatin, Z.; Santos, C.; Martins, V.; Nolasco, GustavoCitrus is grown in Croatia (approximately 1,500 ha of citrus groves) on the Dalmatian Coast and Islands between 42 and 43°30'N. The major species, Citrus unshiu Marc. (Satsuma mandarin), is grafted on trifoliate rootstock. The presence of Citrus tristeza virus (CTV) in Satsumas in the Neretva Valley Region was previously reported (3). During the course of a biomolecular characterization of isolates from Croatia, 15 budsticks were collected from field- infected, enzyme-linked immunosorbent assay (ELISA)-positive sources during the autumn of 2003 near Kaštela, Split, Metković (Neretva Valley), and on the island of Vis. Isolates were propagated by graft transmission to Madam Vinous sweet orange (SwO) and maintained in an insect-proof greenhouse at 21 to 33° C.
- Presence of Citrus tristeza virus in Angola and São Tomé e Princípe: characterization of isolates based on coat protein gene analysisPublication . Silva, Goncalo; Fonseca, Filomena; Santos, C.; Nolasco, GustavoA first report is given of the presence of Citrus tristeza virus (CTV) in Angola and Sao Tome e Principe. Two out of twenty citrus samples from Sao Tome e Principe and all of the seven samples from Angola were shown by ELISA to contain CTV. The capsid protein gene variants obtained by IC/RT-PCR were characterized by SSCP analysis to test for the presence of different haplotypes in each isolate and nucleotide sequence analysis of each variant leading to a different SSCP pattern, followed by in silico comparison with previously characterized CTV groups. The results confirmed that each isolate could contain different variants, which clustered with the different groups. Variants obtained from each country fitted into the same three clusters.