63 research outputs found
Development of a chlorophyll fluorescence imaging system for the quality assessment of fruits and vegetables
No full textChlorophyll fluorescence has been used for a long time as a powerful tool to
investigate the functioning of the photosynthetic apparatus of photosynthetic organisms. It is
an extremely sensitive technique, though such sensitivity often makes its results very difficult
to decipher. One of its main advantages is that it is a non-destructive technique, which makes
it ideally suited for fast screening of large collections of samples. Traditionally, chlorophyll
fluorescence is measured by specially designed fluorimeters, which perform point
measurements on the sample surface. In the last decade a new approach, chlorophyll
fluorescence imaging, has been developed in order to measure the distribution of chlorophyll
fluorescence emission in two dimensions. Research work in this area is still at an early stage,
and a few research groups developed different approaches to the problem.
The present thesis deals with the development of a chlorophyll fluorescence imaging
system carried out at the Laboratory of Botany of the Limburgs Universitair Centrum and its
application in the field of fruit quality assessment, in the study of plant heavy metal stress, on
the effects of disturbances of the endogenous phytohormone balance and as a diagnostic
method for pre-symptomatic detection of viral infections.
The system is composed of an excitation unit, an imaging unit and a control unit.
Chlorophyll fluorescence is detected by a CCD camera fitted with a red cut-off filter, upon
excitation with xenon lamps filtered with a solution of copper sulphate, which provides a blue
cut-off low-pass filter. A detailed description of the system is presented and relevant technical
issues are discussed. In particular, advantages and drawbacks implied by the technical
solutions adopted are addressed.
The mainstream application of the chlorophyll fluorescence imaging system is in the
field of apple quality assessment. After a description of the typical behavior of an apple in
terms of fluorescence emission as measured by the fluorescence imaging system, results from
various experiments with apple material are reported. The suitability of the technique as a
predictor for development of storage diseases is discussed on the basis of an example of
successful prediction. In experiments with apples grown with or without extra nitrogen
supply, the system proved to be able to detect differences in fluorescence emission related to the nitrogen treatment. New perspectives opened by such result are discussed. Progress made
in using advanced analysis tools like Artificial Neural Networks is also addressed. The system
was used also in an experiment with apples grown in orchards treated with different water
regimes. In this case, unfortunately, the system could not detect any remarkable differences
related to the irrigation regimes.
The fluorescence imaging systems, though designed with special attention to its
application in fruit quality control, can be applied also to other fields of research. A gallery of
three examples of an alternative application is presented. In particular, results are shown from
experiments made on heavy metal treated bean plants, on virus-inoculated Nicotiana
benthamiana and on cytokinin-overexpressing transgenic Pssu-ipt tobaccо.
Heavy metal treated plants showed a variation of fluorescence emission in time
during the metal treatment. Not only the intensity of fluorescence emission changed, but also
its distribution on the leaf, opening the way to speculations about the possible correlation of
the difference observed and the distribution of metal ions within the leaf.
The inoculation of Nicotiana benthamiana plants with pepper mild mottle virus
caused an alteration of the fluorescence emission pattern a few days after the inoculation in
otherwise asymptomatic leaves. A peculiar pattern could be observed, which might be related
to the spreading of the virus from the site of inoculation to other parts of the plant.
Transgenic Pssu-ipt tobacco, characterized by an elevated content of endogenous
cytokinin, also showed a peculiar pattern of fluorescence emission, with altered kinetics in
mesophyll areas at a distance from the main veins. Possible explanations of such phenomenon
are attempted.
In the appendices, the software tools used in this research work are presented. In
particular, a description is given of the following programs:
Grabix: Developed by the author, this is the software that controls the whole
fluorescence imaging system.
KhorosPro 2001, Student edition: This is a very flexible multi-purpose
software suite for image analysis, used to process fluorescence images after
being captured with Grabix.
R: This is the programming language for statistical data analysis used to
extract statistical information from the images. Stuttgart Neural Network Simulator (SNNS): It is the simulator used to
analyze fluorescence images by means of artificial neural networks
Development of a chlorophyll fluorescence imaging system for the quality assessment of fruits and vegetables
No full textChlorophyll fluorescence has been used for a long time as a powerful tool to
investigate the functioning of the photosynthetic apparatus of photosynthetic organisms. It is
an extremely sensitive technique, though such sensitivity often makes its results very difficult
to decipher. One of its main advantages is that it is a non-destructive technique, which makes
it ideally suited for fast screening of large collections of samples. Traditionally, chlorophyll
fluorescence is measured by specially designed fluorimeters, which perform point
measurements on the sample surface. In the last decade a new approach, chlorophyll
fluorescence imaging, has been developed in order to measure the distribution of chlorophyll
fluorescence emission in two dimensions. Research work in this area is still at an early stage,
and a few research groups developed different approaches to the problem.
The present thesis deals with the development of a chlorophyll fluorescence imaging
system carried out at the Laboratory of Botany of the Limburgs Universitair Centrum and its
application in the field of fruit quality assessment, in the study of plant heavy metal stress, on
the effects of disturbances of the endogenous phytohormone balance and as a diagnostic
method for pre-symptomatic detection of viral infections.
The system is composed of an excitation unit, an imaging unit and a control unit.
Chlorophyll fluorescence is detected by a CCD camera fitted with a red cut-off filter, upon
excitation with xenon lamps filtered with a solution of copper sulphate, which provides a blue
cut-off low-pass filter. A detailed description of the system is presented and relevant technical
issues are discussed. In particular, advantages and drawbacks implied by the technical
solutions adopted are addressed.
The mainstream application of the chlorophyll fluorescence imaging system is in the
field of apple quality assessment. After a description of the typical behavior of an apple in
terms of fluorescence emission as measured by the fluorescence imaging system, results from
various experiments with apple material are reported. The suitability of the technique as a
predictor for development of storage diseases is discussed on the basis of an example of
successful prediction. In experiments with apples grown with or without extra nitrogen
supply, the system proved to be able to detect differences in fluorescence emission related to the nitrogen treatment. New perspectives opened by such result are discussed. Progress made
in using advanced analysis tools like Artificial Neural Networks is also addressed. The system
was used also in an experiment with apples grown in orchards treated with different water
regimes. In this case, unfortunately, the system could not detect any remarkable differences
related to the irrigation regimes.
The fluorescence imaging systems, though designed with special attention to its
application in fruit quality control, can be applied also to other fields of research. A gallery of
three examples of an alternative application is presented. In particular, results are shown from
experiments made on heavy metal treated bean plants, on virus-inoculated Nicotiana
benthamiana and on cytokinin-overexpressing transgenic Pssu-ipt tobaccо.
Heavy metal treated plants showed a variation of fluorescence emission in time
during the metal treatment. Not only the intensity of fluorescence emission changed, but also
its distribution on the leaf, opening the way to speculations about the possible correlation of
the difference observed and the distribution of metal ions within the leaf.
The inoculation of Nicotiana benthamiana plants with pepper mild mottle virus
caused an alteration of the fluorescence emission pattern a few days after the inoculation in
otherwise asymptomatic leaves. A peculiar pattern could be observed, which might be related
to the spreading of the virus from the site of inoculation to other parts of the plant.
Transgenic Pssu-ipt tobacco, characterized by an elevated content of endogenous
cytokinin, also showed a peculiar pattern of fluorescence emission, with altered kinetics in
mesophyll areas at a distance from the main veins. Possible explanations of such phenomenon
are attempted.
In the appendices, the software tools used in this research work are presented. In
particular, a description is given of the following programs:
Grabix: Developed by the author, this is the software that controls the whole
fluorescence imaging system.
KhorosPro 2001, Student edition: This is a very flexible multi-purpose
software suite for image analysis, used to process fluorescence images after
being captured with Grabix.
R: This is the programming language for statistical data analysis used to
extract statistical information from the images. Stuttgart Neural Network Simulator (SNNS): It is the simulator used to
analyze fluorescence images by means of artificial neural networks
Effects of Three Widely Used Antibiotics and Their Mixture on the Haemocytes of the Clam Ruditapes philippinarum
No full textAlthough the presence of pharmaceutical and personal care products in aquatic
ecosystems is well documented, little information is available about their sublethal
effects, on aquatic invertebrates. From an ecotoxicological point of view, the use of
in vitro approaches has been recommended as a tool to assess adverse effects and to
understand the mechanisms of action of chemicals at the cellular level. In the present
in vitro study, the effects of Amoxicillin (AMX), Trimethoprim (TMP) and Ciprofloxacin (CIP)
(1 μg/L, each) were tested alone and—for the first time—as a mixture (MIX) on haemocytes
of the clam Ruditapes philippinarum. After the exposure, a battery of cellular parameters
was evaluated, such as haemocyte viability, lysosomal membrane stability, superoxide
anion production, acid phosphatase activity, the frequency of micronuclei and
chromosomal aberrations. The results demonstrated that AMX, TMP, CIP and MIX
affected lysosomal membrane stability, as well as superoxide anion and acid
phosphatase production, and promoted chromosomal aberrations. This study
highlighted that Manila clam haemocytes are a sensitive cell model to assess the
effects of exposure to pharmaceutical products on non-target species. Our study
demonstrated that the effects of pharmaceutical mixtures on marine species should be
experimentally evaluated because they are not predictable from single exposures as the
compounds can interact in different ways on the various biological endpoints considered
Ecotoxicological effects and bioaccumulation of BPA analogues and their mixture in the clam Ruditapes philippinarum
No full textBisphenol A is recognized as an endocrine disruptor that can affect several biological processes in marine species. Consequently, its use has been restricted and it has been replaced with other similar compounds named bisphenol A analogues (BPA analogues). BPA analogues are speculatively considered safer compounds than BPA and their usage is increasing with a consequent higher environmental release. In this study, specimens of the clam Ruditapes philippinarum were exposed to three main BPA analogues, namely BPAF, BPF, BPS and their mixture at an environmentally relevant concentration of 300 ng/L for 7 and 14 days. Effects on biomarkers indicative of cytotoxicity, oxidative stress and damage and neurotoxicity were evaluated. In addition, bioaccumulation of the compound tested was analysed in clam soft tissues. Results showed that BPA analogues at an environment concentration affected cellular parameters and antioxidant system causing also oxidative damage, suggesting that BPA analogues can be harmful compounds for clams
Can BPA Analogs Affect Cellular and Biochemical Responses in the Microalga Phaeodactylum tricornutum Bohlin?
No full textBisphenol A analogs (BPA analogs) are emerging contaminants with a rising production caused by the replacement of BPA with these compounds. The increased production of BPA analogs is leading to their increased release into various ecosystems, including marine ones. The aim of this study was to evaluate the biological effects of BPA analogs on a primary producer, the diatom Phaeodactylum tricornutum Bohlin. Three different BPA analogs (BPAF, BPF, and BPS) and their mixture were tested at the environmental relevant concentration of 300 ng/L. Growth, cell size and several biomarkers of oxidative stress and oxidative damage were measured. Our results indicated that the tested compounds caused a reduced growth rate and induced oxidative stress, altering many antioxidant enzymes in P. tricornutum. However, no oxidative damages were observed
The person between liberalism and democracy in the political thought of Maria Zambrano
No full textopenA partire dalla lettura delle opere di María Zambrano Orizzonte del liberalismo e Persona e democrazia, maturate nel contesto storico segnato dall’ascesa dei totalitarismi, la tesi intende ricostruire la centralità del tema della persona che emerge nella proposta avanzata dalla Filosofa andalusa di un rinnovato liberalismo, fondato oltreché sulla libertà personale, sulla socializzazione dell’economia e su di una nuova definizione della democrazia, intesa come l’unico sistema politico che permette la piena fioritura dell’essere umano nella sua dimensione individuale e sociale.Starting from the reading of María Zambrano’s works Horizon of Liberalism and Person and Democracy, written in the historical context marked by the rise of totalitarian regimes, the thesis aims to reconstruct the centrality of the theme of the person as it emerges in the andalusian Philosopher’s proposal for a renewed liberalism, which is founded not only on personal freedom, but also on the socialization of the economy and on a new definition of democracy, understood as the only political system that allows for the full flourishing of the human being in both their individual and social dimensions
Effects of Bisphenol A analogues and their mixture on the crab Carcinus aestuarii: Cytotoxicity, oxidative stress and damage, neurotoxicity, physiological responses, and bioaccumulation
No full textBisphenol A (BPA) analogues are emerging contaminants, whose ecotoxicological profile for aquatic species, particularly marine ones, is little known. In this study, the effects of an environmentally realistic concentration (300 ng/L) of three BPA analogues (BPAF, BPF, and BPS) - alone or as a mixture (MIX) – were evaluated for the first time on the crab Carcinus aestuarii. A multibiomarker approach was adopted to assess the effects of 7 and 14 days of exposure on haemolymph parameters, gill and hepatopancreas biochemical parameters, and physiological responses of crabs. Bioaccumulation of the three bisphenols was also investigated in crabs by UHPLC-HRMS. A significant reduction in total haemocyte counts was recorded in crabs exposed for 7 days to BPAF and MIX and for 14 days to the MIX, whereas an increase was found in crabs treated for 14 days with BPAF. Cell proliferation increased significantly in crabs exposed for 14 days to BPS and MIX. An imbalance of the antioxidant system, as well as oxidative damage, was recorded in gills and hepatopancreas. No neurotoxic effects were observed in crabs. At the physiological level, exposure to MIX increased the respiration rate of crabs. As for bioaccumulation, only bisphenol AF was detected in crabs. Overall, the present study demonstrated that BPA analogues can affect some important cellular parameters, induce oxidative stress and alter physiological responses in crabs
First Evidence of In Vitro Effects of C6O4—A Substitute of PFOA—On Haemocytes of the Clam Ruditapes philippinarum
No full textAlternative chemicals to per- and poly-fluoroalkyl substances have recently been introduced in various industrial processes. C6O4 (difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1,3-dioxolan-4-yl]oxy}acetic acid) is a new surfactant and emulsifier used as a replacement for perfluorooctanoic acid (PFOA). From an ecotoxicological point of view, in vitro assays are useful tools for assessing the negative effects and understanding the mechanisms of action of chemicals at the cellular level. Here, we present the results of an in vitro study in which the effects of C6O4 were evaluated—for the first time—on haemocytes of the clam Ruditapes philippinarum. Cells were exposed to three concentrations of C6O4 (0.05, 0.5, 5 μg/mL) and the effects on haemocyte viability, haemocyte morphology, differential haemocyte count, lysosomal membrane stability, superoxide anion production, acid phosphatase, and β-glucuronidase activities, as well as on the percentage of micronuclei and chromosomal aberrations were evaluated. The results demonstrated that C6O4 significantly affected haemocyte morphology, lysosomal membrane stability, hydrolytic enzyme activity, and superoxide anion production, and promoted chromosomal aberrations. To the best of our knowledge, this is the first study revealing the in vitro effects of C6O4, a substitute for PFOA, on haemocytes from a bivalve species
Assessing the Effects of a Diet of BPA Analogue-Exposed Microalgae in the Clam Ruditapes philippinarum
No full textIn our previous study, we demonstrated that the microalgae Phaeodactylum tricornutum can
bioaccumulate bisphenol A analogues. Since this microalgae species is part of the diet of marine
filter-feeding organisms, such as bivalves, in this study we tested the hypothesis that a diet based on
exposed microalgae can exert negative effects on the clam Ruditapes philippinarum. Microalgae were
exposed for 7 days to 300 ng/L of bisphenol AF (BPAF), bisphenol F (BPF), and bisphenol S (BPS),
alone or as a mixture (MIX), to allow bioaccumulation. Microalgae were then supplied as food to
bivalves. After 7 and 14 days of diet, the effects of exposed microalgae were evaluated on a battery of
biomarkers measured in haemolymph/haemocytes, gills and digestive glands of clams. In addition,
bioaccumulation of the three bisphenols was investigated in clams by UHPLC-HRMS. The results
obtained demonstrated that total haemocyte count (THC) increased in clams following ingestion for
7 days of BPAF- and BPF-exposed microalgae, while BPS-exposed microalgae significantly reduced
THC after 14 days of diet. MIX- and BPS-exposed microalgae increased haemocyte proliferation.
The diet of exposed microalgae affected acid and alkaline phosphatase activity in clams, with an
opposite response between haemolymph and haemocytes. Regarding antioxidants, an increase in
catalase activity was observed in clams after ingestion of BPA analogue-exposed microalgae. The
results also demonstrated marked oxidative stress in gills, the first tissue playing an important role in
the feeding process. Oxidative damage was recorded in both the gills and digestive glands of clams
fed BPA analogue-exposed microalgae. Alterations in epigenetic-involved enzyme activity were
also found, demonstrating for the first time that BPA analogue-exposed food can alter epigenetic
mechanisms in marine invertebrates. No bioaccumulation of BPA analogues was detected in clam
soft tissues. Overall, this study demonstrated that a diet of BPA analogue-exposed microalgae can
induce significant alterations of some important biological responses of R. philippinarum. To our
knowledge, this is the first study demonstrating the effects of ingestion of BPA analogue-exposed
microalgae in the clam R. philippinarum, suggesting a potential ecotoxicological risk for the marine
food chain, at least at the first levels
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