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Dive into the research topics where Maria Teresa Giardi is active.

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Featured researches published by Maria Teresa Giardi.


Planta | 1996

Long-term drought stress induces structural and functional reorganization of photosystem II

Maria Teresa Giardi; A. Cona; B. Geiken; Tomáš Kučera; Jiří Masojídek; Autar K. Mattoo

Long-term drought stress on photosystem II (PSII) was studied in pea (Pisum sativum L.) seedlings. Drought stress (reduction of water content by 35–80%) led to a considerable depletion of the PSII core, and the remaining PSII complex appeared to be functional and reorganized, with a unit size (LHCP/PSII core) twofold greater than that of well-irrigated plants. By immunoblotting analysis of the PSII proteins from grana and stroma lamellae, the enhanced degradation of CP43 and D1 proteins was observed in water-stressed plants. Also, water stress caused increased phosphorylation of the PSII core and increased D1 protein synthesis. Water-stress-mediated increase in D1 synthesis did not occur when plants were exposed to photoinhibitory light. The depletion of the PSII core was essentially reversed when water-stressed plants grown at low visible irradiance were watered. We suggest that the syndrome caused by the effect of long-term water stress on photosynthesis is a combination of at least two events: a reduction in the number of active PSII centres caused by a physical destabilization of the PSII core and a PSII reorganization with enhanced D1 turnover to counteract the core depletion.


Biosensors and Bioelectronics | 2001

Photosystem II-based biosensors for the detection of pollutants

Maria Teresa Giardi; Michal Koblizek; Jirı́ Masojı́dek

Photosystem II (PSII) is the supramolecular pigment-protein complex in the chloroplast, which catalyses the light-induced transfer of electrons from water to plastoquinone (PQ) in a process that evolves oxygen. The PSII complex is also known to bind some groups of (photosynthetic) herbicides, heavy metals and other chemical substances that affect its activity. The objective of this study is to provide an overview of the systems available for the bioassay of pollutants using biosensors that are based on the photochemical activity of PSII. Some applications of the PSII-based biosensors including herbicide, heavy metal monitoring and the detection of radiation in space experiments are reported.


Biotechnology and Bioengineering | 1998

A Sensitive Photosystem II-Based Biosensor for Detection of a Class of Herbicides

Michal Koblizek; Jiri Masojidek; Josef Komenda; Tomáš Kučera; Roberto Pilloton; Autar K. Mattoo; Maria Teresa Giardi

We have developed a biosensor for the detection of residual triazine-, urea- and phenolic-type herbicides, using isolated photosystem II (PSII) particles from the thermophilic cyanobacterium, Synechococcus elongatus, as biosensing elements. The herbicide detection was based on the fact that, in the presence of artificial electron acceptors, the light-induced electron transfer through isolated PSII particles is accompanied by the release of oxygen, which is inhibited by the herbicide in a concentration-dependent manner. The PSII particles were immobilized between dialysis membrane and the Teflon membrane of the Clark oxygen electrode mounted in a flow cell that was illuminated. Inclusion of the antibiotic chloramphenicol in the reaction mixtures prolonged, by 50%, the lifetime of the biosensor. The use of highly active PSII particles in combination with the flow system resulted in a reusable herbicide biosensor with good stability (50% of initial activity was still remaining after 35-h use at 25 degrees C) and high sensitivity (detection limit for diuron was 5 x 10(-10) M).


Biosensors and Bioelectronics | 2009

Optical biosensors for environmental monitoring based on computational and biotechnological tools for engineering the photosynthetic D1 protein of Chlamydomonas reinhardtii

Maria Teresa Giardi; Viviana Scognamiglio; Giuseppina Rea; Giuseppe Rodio; Amina Antonacci; Maya D. Lambreva; Gianni Pezzotti; Udo Johanningmeier

Homology-based protein modelling and computational screening followed by virtual mutagenesis analyses were used to identify functional amino acids in the D1 protein of the photosynthetic electron transfer chain interacting with herbicides. A library of functional mutations in the unicellular green alga Chlamydomonas reinhardtii for preparing biomediators was built and their interactions with herbicides were calculated. D1 proteins giving the lowest and highest binding energy with herbicides were considered as suitable for preparing the environmental biosensors for detecting specific herbicide classes. Arising from the results of theoretical calculations, three mutants were prepared by site-directed mutagenesis and characterized by fluorescence analysis. Their adsorption and selective recognition ability were studied by an equilibrium-adsorption method. The S268C and S264K biomediators showed high sensitivity and resistance, respectively, to both triazine and urea classes of herbicides. When immobilized on a silicon septum, the biomediators were found to be highly stable, remaining so for at least 1-month at room temperature. The fluorescence properties were exploited and a reusable and portable multiarray optical biosensor for environmental monitoring was developed with limits of detection between 0.8 x 10(-11) and 3.0 x 10(-9), depending on the target analyte. In addition, biomediator regeneration without obvious deterioration in performance was demonstrated.


Journal of Agricultural and Food Chemistry | 2010

New platform of biosensors for prescreening of pesticide residues to support laboratory analyses.

Katia Buonasera; Gianni Pezzotti; Viviana Scognamiglio; Arianna Tibuzzi; Maria Teresa Giardi

Millions of tons of pesticides are applied worldwide annually in agriculture. Among them, herbicides such as triazines and ureas, originating from agricultural runoff, can contaminate soils and surface and ground waters with severe toxic effects on humans. Nowadays, different analytical techniques are available for the detection of these chemicals; however, most of them are expensive and time-consuming, especially in the case of routine analyses. For this reason, on the basis of results collected through many years of experience in the field of photosynthetic organisms, we designed a biosensor platform intended for the easy, low-cost, and fast prescreening of photosynthetic herbicides. The platform combines the possibilities of amperometric and optical transduction systems, which have proven to be highly sensitive (limits of detection = 10(-10)-10(-8) M). The use of genetically modified algae strengthens the power of the platform, allowing different subclasses of herbicides to be recognized. The system has been validated for the analysis of environmental water and is proposed to support laboratories involved in the control of water pollution.


Plant Science | 1999

Modulation of D1 protein turnover under cadmium and heat stresses monitored by [35S]methionine incorporation

Emanuel Franco; Sabrina Alessandrelli; Jiri Masojidek; Andrea Margonelli; Maria Teresa Giardi

Abstract This study examined the response of Photosystem II (PSII) to heavy metal and heat stresses and their combination in two higher plant species, pea (Pisum sativum) and broad beans (Vicia faba). The photochemical activity of PSII was monitored as the maximum fluorescence yield of PSII, Fv/Fm, in leaves and as DCPIP photoreduction in thylakoids isolated from control and treated leaves. The pre-treatment of plants with cadmium (1 mM CdCl2) induced a temporary protection of PSII activity against heat stress (38°C). On the contrary, pre-treatment at the high temperature did not protect PS II against heavy metal (1 mM CdCl2) stress. The pulse-chase experiments with [35S]methionine demonstrated that the two types of stress had different consequences on D1 protein turnover. When the plants were subjected to the cadmium treatment (Cd-treatment), net D1 synthesis was first stimulated, and then inhibited. Heat stress, however, caused an immediate decline of net D1 synthesis. In response to the simultaneous imposition of both stresses, D1 turnover remained stable initially for several hours, but was greatly inhibited under prolonged treatment. Both treatments resulted in a decrease of the D1 level. The symptoms of heavy metal stress were particularly evident when D1 turnover was scarcely stimulated.


Analytical and Bioanalytical Chemistry | 2011

Technological applications of chlorophyll a fluorescence for the assessment of environmental pollutants.

Katia Buonasera; Maya D. Lambreva; Giuseppina Rea; Eleftherios Touloupakis; Maria Teresa Giardi

Chlorophyll a fluorescence has been extensively studied over the last few years. As demonstrated, this phenomenon is closely related to the state of photosystem II, which plays a leading role in the photosynthetic process, and therefore it has become a powerful tool to investigate this complex and any damage occurring in it as a result of physical or chemical stresses. This means that by using photosynthetic organisms as biological probes, one can consider chlorophyll a fluorescence as one of the techniques of choice to reveal the presence of some hazardous toxicants widely spread in the environment. Herbicides, pesticides, and heavy metals, whose concentration in water and food products is generally subject to extremely severe restrictions, are a concrete example of compounds detectable by chlorophyll a fluorescence. These dangerous substances react with the photosystem II, modifying the fluorescence emitted and giving responses which vary in a concentration-dependent manner. The possibility of performing easy, fast, and direct measurements of the fluorescence, even under light conditions, has opened new frontiers for the analysis in situ of pollutants. The aim of this review is to give an overview of the different techniques based on chlorophyll a fluorescence spectrometry, focusing in particular on those which represented the starting point for applications addressed to the assessment of toxic compounds in environmental samples.


Protein Science | 2009

Structure‐based design of novel Chlamydomonas reinhardtii D1‐D2 photosynthetic proteins for herbicide monitoring

Giuseppina Rea; Fabio Polticelli; Amina Antonacci; Viviana Scognamiglio; Prashant Katiyar; Sudhir Kulkarni; Udo Johanningmeier; Maria Teresa Giardi

The D1‐D2 heterodimer in the reaction center core of phototrophs binds the redox plastoquinone cofactors, QA and QB, the terminal acceptors of the photosynthetic electron transfer chain in the photosystem II (PSII). This complex is the target of the herbicide atrazine, an environmental pollutant competitive inhibitor of QB binding, and consequently it represents an excellent biomediator to develop biosensors for pollutant monitoring in ecosystems. In this context, we have undertaken a study of the Chlamydomonas reinhardtii D1‐D2 proteins aimed at designing site directed mutants with increased affinity for atrazine. The three‐dimensional structure of the D1 and D2 proteins from C. reinhardtii has been homology modeled using the crystal structure of the highly homologous Thermosynechococcus elongatus proteins as templates. Mutants of D1 and D2 were then generated in silico and the atrazine binding affinity of the mutant proteins has been calculated to predict mutations able to increase PSII affinity for atrazine. The computational approach has been validated through comparison with available experimental data and production and characterization of one of the predicted mutants. The latter analyses indicated an increase of one order of magnitude of the mutant sensitivity and affinity for atrazine as compared to the control strain. Finally, D1‐D2 heterodimer mutants were designed and selected which, according to our model, increase atrazine binding affinity by up to 20 kcal/mol, representing useful starting points for the development of high affinity biosensors for atrazine.


Talanta | 2008

Development of a photosystem II-based optical microfluidic sensor for herbicide detection.

Dimitrios G. Varsamis; Eleftherios Touloupakis; Pietro Morlacchi; Demetrios F. Ghanotakis; Maria Teresa Giardi; David C. Cullen

Herbicides are highly toxic for both human and animal health. The increased application of herbicides in agriculture during the last decades has resulted in the contamination of both soil and water. Herbicides, under illumination, can inhibit photosystem II electron transfer. Photosynthetic membranes isolated from higher plants and photosynthetic micro-organisms, immobilized and stabilized, can serve as a biorecognition element for a biosensor. The inhibition of photosystem II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase. In the present work, a compact and portable sensing device that combines the production and detection of hydrogen peroxide in a single flow assay is proposed for herbicide detection.


Critical Reviews in Food Science and Nutrition | 2013

Healthy and adverse effects of plant-derived functional metabolites: the need of revealing their content and bioactivity in a complex food matrix.

Teresa Lavecchia; Giuseppina Rea; Amina Antonacci; Maria Teresa Giardi

In recent years, both food quality and its effect on human health have become a fundamental issue all over the world. As a consequence of this new and increased awareness, American, European, and Asian policymakers have strongly encouraged the research programs on food quality and safety thematic. Attempts to improve human health and to satisfy peoples desire for healthcare without intake of pharmaceuticals, has led the food industry to focus attention on functional or nutraceutical food. For a long time, compounds with nutraceutical activity have been produced chemically, but the new demands for a sustainable life have gradually led the food industry to move towards natural compounds, mainly those derived from plants. Many phytochemicals are known to promote good health, but, sometimes, undesirable effects are also reported. Furthermore, several products present on the market show few benefits and sometimes even the reverse - unhealthy effects; the evidence of efficacy is often unconvincing and epidemiological studies are necessary to prove the truth of their claims. Therefore, there is a need for reliable analytical control systems to measure the bioactivity, content, and quality of these additives in the complex food matrix. This review describes the most widespread nutraceutics and an analytical control of the same using recently developed biosensors which are promising candidates for routine control of functional foods.

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Giuseppina Rea

National Research Council

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Gianni Pezzotti

National Research Council

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Amina Antonacci

National Research Council

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Dania Esposito

National Research Council

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Maya D. Lambreva

Bulgarian Academy of Sciences

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Katia Buonasera

National Research Council

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Alba Zanini

Istituto Nazionale di Fisica Nucleare

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