Conceição Santos

University of Aveiro, Aveiro, Aveiro, Portugal

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Publications (80)165.51 Total impact

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    ABSTRACT: Background & Scope of the review: This review focuses on the UV radiation effects on skin, emphasizing the photoaging process, and the photoprotection conferred by tretinoin (all-trans retinoic acid or ATRA). Tretinoin is still the best tested retinoid to reverse photoaged skin. Major Conclusions: Tretinoin can be used for photoaging treatment or combined treatment by different mechanisms. It binds to and activates retinoic acid receptors, inducing changes in gene expression that leads to cell differentiation, decreased cell proliferation, and inhibition of tumourigenesis. It has been demonstrated that photoaging resulting from UV-B radiation can be treated by retinoid formulations. Pretreatment of human skin with tretinoin blocks dermal matrix degradation followed by sun exposure, inhibiting the induction of the activated protein-1 (AP-1) transcription factor and AP-1 regulated matrix-degrading metalloproteinases. General Significance and Interest: Tretinoin should be considered as a key factor as it is the most potent and best-studied retinoid. In addition, the development of advanced drug delivery systems, especially novel nanoformulations, has contributed to overpass some technical drawbacks besides the skin irritation potential. The triple combination of tretinoin, hydroquinone and corticosteroids is still considered the gold standard for melasma. Although there are other novel therapeutic approaches, more high-quality clinical trials are still needed.
    Mini Reviews in Medicinal Chemistry 08/2014; · 2.87 Impact Factor
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    ABSTRACT: Background & Scope of the reviewThis review focuses on the photoprotection conferred by lycopene, one of the most potent antioxidants. Lycopene has been recently proposed to play a critical role on anticarcinogenic action at different levels.Major Conclusions The photoprotective properties of lycopene remain contradictory. Some studies point out a positive and others a negative effect in both in vitro and in vivo models. Currently, researchers recognize that crucial gaps exist in understanding the role of carotenoids as effective modulators of apoptosis, cell cycle dynamics and/or of their in vivo behavior as cellular antioxidants.General SignificanceThe development of novel therapeutic strategies for skin disorders depends on our understanding of the molecular mechanism of UV damage on skin cells. The use of several effective phytocompounds, including lycopene, working through preventive and/ or corrective pathways in the cell, may be an approach for reducing UV-B generated damage.This article is protected by copyright. All rights reserved.
    Experimental Dermatology 07/2014; · 3.58 Impact Factor
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    ABSTRACT: Ultradeformable vesicles are highly promising tools to enhance the percutaneous transport of different drugs such as tretinoin across the skin barrier, and also to increase the formulationstability at absorption site and reduce the drug induced irritation.
    European Journal of Pharmaceutics and Biopharmaceutics. 05/2014;
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    ABSTRACT: Hormonal conditioning of plants in order to increase photosynthetic performance and reduce oxidative stress may improve plants’ tolerance to stress. This study aims to elucidate the effects of ABA pretreatment on the photosynthetic apparatus and antioxidant battery of Ulmus minor plants under well watered (WW) and drought stress (DS) conditions. Leaves were sprayed with ABA (50 and 100 μM). After 25 days of treatment DS was initiated by withholding water for 6 days. Water deficit decreased the RWC, induced stomatal closure and impaired net CO2 assimilation rate (A). However, independently of the water regime, ABA pretreatment increased plant DW accumulation, A, carotenoids and Chl a contents and reduced water loss. DS induced oxidative stress, but ABA application increased DS tolerance by the enhancement of the antioxidant system. Under WW conditions, the benefits of ABA application in reducing the cell membrane damages were noticeable. ABA pretreatment and DS induced changes in U. minor cell cycle of leaf cells, with a delay in S phase and an increase of FPCV coefficient. We propose that ABA pretreatment improves plant performance by increasing plant DW accumulation and augmenting the antioxidant system of U. minor plants, not only under DS conditions, but also under WW conditions. The use of ABA as pretreatment to alleviate the negative effects of DS seems to be a promising strategy to reduce plant's loss and improve plant productivity in drought prone habitats.
    Environmental and Experimental Botany 04/2014; · 3.00 Impact Factor
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    ABSTRACT: Osteosarcoma is a recalcitrant bone malignancy with poor responsiveness to treatments; therefore, new chemotherapeutic compounds are needed. Sulforaphane (SFN) has been considered a promising chemotherapeutic compound for several types of tumors by inducing apoptosis and cytostasis, but its effects (e.g., genotoxicity) in osteosarcoma cells remains exploratory. In this work, the MG-63 osteosarcoma cell line was exposed to SFN up to 20 μM for 24 and 48 h. SFN induced G2/M phase arrest and decreased nuclear division index, associated with disruption of cytoskeletal organization. Noteworthy, SFN induced a transcriptome response supportive of G2/M phase arrest, namely a decrease in Chk1- and Cdc25C-encoding transcripts, and an increase in Cdk1-encoding transcripts. After 48-h exposure, SFN at a dietary concentration (5 μM) contributed to genomic instability in the MG-63 cells as confirmed by increased number of DNA breaks, clastogenicity, and nuclear and mitotic abnormalities. The increased formation of nucleoplasmic bridges, micronuclei, and apoptotic cells positively correlated with loss of viability. These results suggest that genotoxic damage is an important step for SFN-induced cytotoxicity in MG-63 cells. In conclusion, SFN shows potential to induce genotoxic damage at low concentrations and such potential deserves further investigation in other tumor cell types.
    Nutrition and Cancer 01/2014; · 2.70 Impact Factor
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    ABSTRACT: This paper describes a proton high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) metabolomic study of lettuce (Lactuca sativa L) leaves to characterise metabolic adaptations during leaf growth and exposure to mancozeb. Metabolite variations were identified through multivariate analysis and checked through spectral integration. Lettuce growth was accompanied by activation of energetic metabolism, preferential glucose use and changes in amino acids, phospholipids, ascorbate, nucleotides and nicotinate/nicotinamide. Phenylalanine and polyphenolic variations suggested higher oxidative stress at later growth stages. Exposure to mancozeb induced changes in amino acids, fumarate and malate, suggesting Krebs cycle up-regulation. In tandem disturbances in sugar, phospholipid, nucleotide and nicotinate/nicotinamide metabolism were noted. Additional changes in phenylalanine, dehydroascorbate, tartrate and formate were consistent with a higher demand for anti-oxidant defence mechanisms. Overall, lettuce exposure to mancozeb was shown to have a significant impact on plant metabolism, with mature leaves tending to be more extensively affected than younger leaves.
    Food Chemistry 01/2014; 154:291-298. · 3.33 Impact Factor
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    ABSTRACT: Cork oak (Quercus suber L.) is a research priority in the Mediterranean area and because of cork oaks’ distribution these stands are experiencing daily stress. Based on projections of intensifying climate change and considering the key role of exploring the recovery abilities, cork oak seedlings were subjected to a cumulative temperature increase from 25 °C to 55 °C and subsequent recovery. CO2 assimilation rate, chlorophyll fluorescence, anthocyanins, proline and lipid peroxidation were used to evaluate plant performance, while the relative abundance of seven genes encoding for proteins of cork oak with a putative role in thermal/stress regulation (POX1, POX2, HSP10.4, HSP17a.22, CHS, MTL and RBC) was analyzed by qPCR (quantitative Polymerase Chain Reaction). A temperature change to 35 °C showed abundance alterations in the tested genes; at 45 °C, the molecular changes were associated with an antioxidant response, possibly modulated by anthocyanins. At 55 °C, HSP17a.22, MTL and proline accumulation were evident. After recovery, physiological balance was restored, whereas POX1, HSP10.4 and MTL abundances were suggested to be involved in increased thermotolerance. The data presented here are expected to pinpoint some pathways changes occurring during such stress and further recovery in this particular Mediterranean species.
    Journal of plant physiology 01/2014; 171(6):399–406. · 2.50 Impact Factor
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    ABSTRACT: Sulforaphane (SFN) is a naturally-occurring isothiocyanate best known for its role as an indirect antioxidant. Notwithstanding, in different cancer cell lines, SFN may promote the accumulation of reactive oxygen species (ROS) and cause cell death e.g. by apoptosis. Osteosarcoma often becomes chemoresistant, and new molecular targets to prevent drug resistance are needed. Here, we aimed to determine the effect of SFN on ROS levels and to identify key biomarkers leading to ROS unbalance and apoptosis in the p53-null MG-63 osteosarcoma cell line. MG-63 cells were exposed to SFN for up to 48 h. At 10 μM concentration or higher, SFN decreased cell viability, increased the%early apoptotic cells and increased caspase 3 activity. At these higher doses, SFN increased ROS levels, which correlated with apoptotic endpoints and cell viability decline. In exposed cells, gene expression analysis revealed only partial induction of phase-2 detoxification genes. More importantly, SFN inhibited ROS-scavenging enzymes and impaired glutathione recycling, as evidenced by inhibition of glutathione reductase (GR) activity and combined inhibition of glutathione peroxidase (GPx) gene expression and enzyme activity. In conclusion, SFN induced oxidative stress and apoptosis via a p53-independent mechanism. GPx expression and activity were found associated with ROS accumulation in MG-63 cells and are potential biomarkers for the efficacy of ROS-inducing agents e.g. as co-adjuvant drugs in osteosarcoma.
    PLoS ONE 01/2014; 9(3):e92980. · 3.53 Impact Factor
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    ABSTRACT: This paper presents a new combination, Calendula suffruticosa subsp. cinerea, and two lectotypifications, for Calendula suffruticosa subsp. tomentosa and Calendula suffruticosa subsp. cinerea, in the course of a taxonomic revision for Flora Iberica. Explanations about the taxonomic concept here adopted are also provided.
    Phytotaxa 10/2013; 145(1):47-53. · 1.30 Impact Factor
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    ABSTRACT: Cork oak is an economically important forest species showing a great tolerance to high temperatures and shortage of water. However, the mechanisms underlying this plasticity are still poorly understood. Among the stress regulators, transcription factors (TFs) are especially important since they can control a wide range of stress-inducible genes, which make them powerful targets for genetic engineering of stress tolerance. Here we evaluated the influence of increasing temperatures (up to 55 °C) or drought (18% field capacity, FC) on the expression profile of an R2R3-MYB transcription factor of cork oak, the QsMYB1. QsMYB1 was previously identified as being preferentially expressed in cork tissues and as having an associated alternative splicing mechanism, which results in two different transcripts (QsMYB1.1 and QsMYB1.2). Expression analysis by reverse transcription quantitative PCR (RT-qPCR) revealed that increasing temperatures led to a gradual down-regulation of QsMYB1 transcripts with more effect on QsMYB1.1 abundance. On the other hand, under drought condition, expression of QsMYB1 variants, mainly the QsMYB1.2, was transiently up-regulated shortly after the stress imposition. Recovery from each stress has also resulted in a differential response by both QsMYB1 transcripts. Several physiological and biochemical parameters (plant water status, chlorophyll fluorescence, lipid peroxidation and proline content) were determined in order to monitor the plant performance under stress and recovery. In conclusion, this report provides the first evidence that QsMYB1 TF may have a putative function in the regulatory network of cork oak response to heat and drought stresses and during plant recovery.
    Plant Physiology and Biochemistry 10/2013; 73C:274-281. · 2.78 Impact Factor
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    ABSTRACT: Eucalyptus plantations are among the most productive forest stands in Portugal and Spain, being mostly used for pulp production and, more recently, as an energy crop. However, the region's Mediterranean climate, with characteristic severe summer drought, negatively affects eucalypt growth and increases mortality. Although the physiological response to water shortage is well characterized for this species, evidence about the plants' recovery ability remains scarce. In order to assess the physiological and biochemical response of E. globulus during the recovery phase, two genotypes (AL-18 and AL-10) were submitted to a three-week water stress period at two different intensities (18% and 25% of field capacity), followed by one week of rewatering. Recovery was assessed one day and one week after rehydration. Drought reduced height, biomass, water potential, NPQ and gas exchange in both genotypes. Contrarily, the levels of pigments, chlorophyll fluorescence parameters (Fv /Fm and ɸPSII ), MDA and ABA increased. During recovery, the physiological and biochemical profile of stressed plants showed a similar trend: they experienced reversion of altered traits (MDA, ABA, E, gs , pigments), while other parameters did not recover (ɸPSII , NPQ). Furthermore, an overcompensation of CO2 assimilation was achieved one week after rehydration, which was accompanied by greater growth and re-establishment of oxidative balance. Both genotypes were tolerant to the tested conditions, although clonal differences were found. AL-10 was more productive and showed a more rapid and dynamic response to rehydration (namely in carotenoid content, ɸPSII and NPQ) compared to clone AL-18.
    Physiologia Plantarum 10/2013; · 3.66 Impact Factor
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    ABSTRACT: This experimental work aimed to develop a simple, fast, economic and environmental friendly process for the extraction of lycopene from tomato and incorporate this lycopene-rich-extract in ultradeformable vesicular nanocarriers suitable for topical application. The lycopene extraction was carried out without a co-solvent for 30 min. The extracts were analyzed and incorporated in transfersomes and ethosomes. These formulations were characterized and the cellular uptake was observed by confocal microscopy. Dermal delivery of lycopene formulations was tested in vitro and in vivo conditions. Lycopene extraction proved to be quite safe and selective. The vesicular formulation was uptaken by the cells being more concentrated around the nucleus. Lycopene formulations epicutaneous application decreased anthralin-induced ear swelling by 97% and 87%, in a non-statistically different manner from the positive control. These results support that the lycopene-rich extract may be a good alternative to the expensive commercial lycopene to be incorporated in advanced topical delivery systems.
    Journal of Agricultural and Food Chemistry 07/2013; · 3.11 Impact Factor
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    Glória Pinto, Clara Araújo, Conceição Santos, Lucinda Neves
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    ABSTRACT: Forest tree improvement programs benefit from the emergence of new biotechnological strategies that complement plant developmental biology and discovery of genes associated with complex multigenic traits. Recently, significant progress has been made in the area of plant regeneration via somatic embryogenesis (SE) for economically important tree species (e.g. pines). These advances have opened up new scenarios for deployment of new high-performance clonally replicated planting stock to forest plantations and may also be a valuable tool for the development of efficient gene transfer techniques. Although high rates of plant propagation from axillary shoot proliferation can be achieved easily in many Eucalyptus species, even higher multiplication rates through SE have been recorded in other tree species. If the clonal propagation of Eucalyptus through SE proves to be an effective propagation method, it has the potential to meet the increasing industrial demands for high-quality uniform materials and to rapidly capture the benefits of breeding programs. Since 2002 a reproducible protocol for SE induction from mature zygotic embryos of E. globulus has been available. However, for SE to be useful in E. globulus improvement programs, the frequency of SE initiation, maturation, germination and acclimatisation needs to be improved and controlled. If this technology could be extended to elite germplasm, it would become an economically feasible tool for large-scale production and delivery of improved planting stock. This is one of the greatest current challenges in Eucalyptus tissue culture. In this review we update the most important aspects of SE in Eucalyptus with particular emphasis on E. globulus. We highlight both genetic control and the influence of different environmental factors in the SE process (e.g. medium composition, antioxidants, light and plant growth regulators), from induction to plant acclimatisation in both primary and secondary SE.
    Southern Forests: a Journal of Forest Science 05/2013; 75(2):59-69. · 0.39 Impact Factor
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    ABSTRACT: Calendula L. (Asteraceae) is a taxonomically and cytologically complex genus due to its high morpho-logical and karyological variation. To gather consistent cytological information aiming to consolidate the existing knowledge, sustain the taxonomic revision of the genus and explore the evolutionary relationships among species, the genome size and chromosome number of the Iberian Pen-insula representatives of this genus were assessed. The study included 11 taxa that occur in the Iberian Peninsula, one in Madeira and two from Morocco. Chromosome counts were made using the squash technique in root tips and flower buds, while nuclear DNA contents were asses-sed using propidium iodide flow cytometry. The following chromosome numbers are reported: 2n = 44 for C. arv-ensis, 2n = 30 for C. tripterocarpa, and 2n = 32 for the remaining Iberian taxa. The genome size of Calendula species was assessed for the first time and ranged from 1.75 pg/2C in C. maroccana to 5.41 pg/2C in C. arvensis. Within the complex formed by C. incana and C. suffruti-cosa, a gradient of genome size values was obtained. Intraspecific variation in genome size was detected in some taxa. The obtained genome size values and their variation are discussed in the light of the theories proposed for the speciation of the genus, with events of hybridization, genome duplication and dysploidy being hypothesized to play a major role in the evolution of this genus.
    Plant Systematics and Evolution 05/2013; 299:853-864. · 1.31 Impact Factor
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    ABSTRACT: Aluminium (Al) toxicity decreases plant growth. Secale cereale L. is among the most Al-tolerant crop species. In order to study the response to Al-long term exposure, two rye genotypes with different Al sensitivity ('D. Zlote' and 'Riodeva') were exposed to 1.11 and 1.85mM Al and the antioxidant responses were followed for 2 and 3 weeks in roots and leaves. Al toxicity signals, such as a severe decrease in root growth, occurred sooner in 'Riodeva.' The antioxidant response was dependent on the genotype, the organ, Al concentration and the exposure period. Al-exposed roots of 'D. Zlote' showed earlier enhancements of APX, SOD and G-POX activities than those of 'Riodeva.' 'D. Zlote' roots showed stimulation of the AsA-GSH cycle after the second week (when root growth inhibition was less severe), while later (when severe root growth inhibition was observed), oxidation of AsA and GSH pools was observed. In leaves of both genotypes, CAT, SOD and G-POX activities increased with Al exposure. In these leaves, the effect of AsA-GSH was time dependent, with maximum oxidation at the second week, followed by recovery. We confirmed that the oxidation state of AsA and GSH pools is involved in the detoxification of Al-induced oxidative stress. Moreover, our data demonstrate that the production of ROS does not correlate with the Al-induced root growth decrease. Finally, the differences observed over time indicate that long term exposure may provide additional information on rye sensitivity to Al, and contribute to a better understanding of this species' mechanisms of Al tolerance.
    Journal of plant physiology 03/2013; · 2.50 Impact Factor
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    Lara Currais, João Loureiro, Conceição Santos, Jorge Canhoto
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    ABSTRACT: Ploidy levels of short-term (1 and 2 years) and long-term (7 and 10 years) embryogenic cultures as well as of regenerated plantlets of tamarillo were analyzed by flow cytometry and chromosome counts. Embryogenic cultures were induced from expanding leaves cultured in the presence of Picloram or 2,4-dichlorophenoxyacetic acid (2,4-D) and monthly subcultured on the same media. Embryo develop-ment and plantlets were obtained following subculture of the embryogenic tissue in auxin free medium containing gib-berellic acid (GA 3). Seedlings and rooted shoots from axil-lary shoot proliferation were used as controls. The results showed that in long-term embryogenic cultures the ability to develop somatic embryos and plantlets was reduced. Embryogenic tissues maintained for 10 years were mostly aneuploids of the tetraploid (2n = 4x = 48) level whereas those kept in culture for 7 years or less were also mostly aneuploids but of the diploid (2n = 2x = 24) level. The results obtained by flow cytometry were, in general, consis-tent with those obtained by chromosome counts. The chro-mosome alteration observed in the embryogenic tissues was already present after 1 year of culture and increased with culture age, hence impairing the maintenance of these tissues for long periods without affecting chromosome stability of the regenerated plantlets. However, the occurrence of triploids and tetraploids as well as aneuploids can be useful for breeding purposes. A value around 23 pg/2C was found for the genome size of tamarillo largely exceeding the value previously published (15.50 pg/2C).
    Plant Cell Tissue and Organ Culture 03/2013; 114:149-159. · 2.61 Impact Factor
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    ABSTRACT: Site-specific risk assessment of contaminated areas indicates prior areas for intervention, and provides helpful information for risk managers. This study was conducted in the Ervedosa mine area (Bragança, Portugal), where both underground and open pit exploration of tin and arsenic minerals were performed for about one century (1857 - 1969). We aimed at obtaining ecotoxicological information with terrestrial and aquatic plant species to integrate in the risk assessment of this mine area. Further we also intended to evaluate if the assessment of other parameters, in standard assays with terrestrial plants, can improve the identification of phytotoxic soils. For this purpose, soil samples were collected on 16 sampling sites distributed along four transects, defined within the mine area, and in one reference site. General soil physical and chemical parameters, total and extractable metal contents were analyzed. Assays were performed for soil elutriates and for the whole soil matrix following standard guidelines for growth inhibition assay with Lemna minor and emergence and seedling growth assay with Zea mays. At the end of the Z. mays assay, relative water content, membrane permeability, leaf area, content of photosynthetic pigments (chlorophylls and carotenoids), malondialdehyde levels, proline content, and chlorophyll fluorescence (Fv/Fm and ΦPSII) parameters were evaluated. In general, the soils near the exploration area revealed high levels of Al, Mn, Fe and Cu. Almost all the soils from transepts C, D and F presented total concentrations of arsenic well above soils screening benchmark values available. Elutriates of several soils from sampling sites near the exploration and ore treatment areas were toxic to L. minor, suggesting that the retention function of these soils was seriously compromised. In Z. mays assay, plant performance parameters (other than those recommended by standard protocols), allowed the identification of more phytotoxic soils. The results suggest that these parameters could improve the sensitivity of the standard assays.
    PLoS ONE 01/2013; 8(4):e59748. · 3.53 Impact Factor
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    ABSTRACT: Candidate species for reforestation of areas prone to drought must combine water stress (WS) tolerance and economic or medicinal interest. Melia azedarach produces high quality timber and has insecticidal and medicinal properties. However, the impact of WS on M. azedarach has not yet been studied. Two-month old M. azedarach plants were exposed to WS during 20 days. After this period, plant’s growth, water potential, photosynthetic performance and antioxidant capacity were evaluated. WS did not affect plants’ growth, but induced stomatal closure, reduced net CO2 assimilation rate (A) and the intercellular CO2 availability in mesophyll (Ci). WS also reduced the photosynthetic efficiency of PSII but not the pigment levels. WS up-regulated the antioxidant enzymes and stimulated the production of antioxidant metabolites, preventing lipid peroxidation. Therefore, despite some repression of photosynthetic parameters by WS, they did not compromise plant growth, and plants increased their antioxidant capacity. Our data demonstrate that M. azedarach juvenile plants have the potential to acclimate to water shortage conditions, opening new perspectives to the use of this species in reforestation/afforestation programs of drought prone areas.
    Plant Physiology and Biochemistry 01/2013; · 2.78 Impact Factor

Publication Stats

583 Citations
165.51 Total Impact Points

Institutions

  • 2002–2014
    • University of Aveiro
      • • Division of Biology
      • • Department of Biology
      Aveiro, Aveiro, Portugal
  • 2010
    • University of Coimbra
      • Departamento de Ciências da Vida
      Coimbra, Distrito de Coimbra, Portugal
  • 2007–2009
    • Instituto Universitario Valle de Santiago
      Santiago, Nayarit, Mexico