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For the development of a bio-sensor based on fluorescence excitation in transmission, a plastic substrate with excellent optical characteristics, such as high optical transmission in the visible range and low self-fluorescence, is required. Polyethylene (PE) films have been found to meet these optical characteristics. However, the adhesion of short sequences of oligonucleotides used as bio-probes, which are needed to develop a genosensor, has not proven ideal on this substrate, due to its olefinic composition. In order to overcome this challenge, a physical-chemical surface modification of PE films has been performed using a corona treatment, followed by the attachment of functional organic compounds. The surface modified substrates have been characterized for their wettability, surface energy, zeta potential and surface topography. The bio-probes’ adhesion on the treated surfaces has been tested by monitoring the fluorescence of dye-conjugated complementary sequences of the oligonucleotides deposited on the modified PE substrates. Finally, two modified PE substrates, comprising the best adhesion of the bio-probes, have been used to prepare a genosensor for the detection of the DNA of the insect Hermetia illucens. As expected, the better adhesion of bio-probes on the functionalized PE substrate has allowed a significant improvement of the bio-sensor’s limit of detection (LOD).

As reported by World Health Organization (WHO), most than half of the word population is potentially at risk to be infected with Dengue virus. This virus is a single strained RNA virus of the flaviviridae family that presents four different serotypes. Secondary infections with different serotypes can induce very dangerous complications, like Dengue haemorrhagic fever and shock syndrome. The tropical and sub-tropical areas are the most affected by this infection. Therefore, there is a strong need of a cheap, portable, fast and sensitive diagnostic test also for economic reasons. In this paper, the development of a Point-of-Care multiparametric system using an organic light emitting diode (OLED)-based biochip for the simultaneous detection of the four different Dengue serotypes, is presented. The system exploits the fluorescence detection of a low density matrix of protein antigens and secondary fluorophore tagged antibodies, excited by an OLED source. A low cost CMOS camera, allowing low light detection, to perform multiparametric quantitative analysis has been used in combination with a specifically developed image processing software. The software pipeline adopted is described as well. Fourty Dengue patient sera, previously characterized by standard diagnostic techniques, have been tested, using 3 μl of sera and an incubation time of 30 minutes. The results of these analysis demonstrate the capability of this diagnostic system to perform early Dengue diagnosis and to recognize the Dengue serotype with very high precision, in particular in convalescent patients.

Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in “La Albufera” Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves—where they are presumably compartmentalized in vacuoles—and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na+ and Cl− contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K+ transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level—estimated from malondialdehyde accumulation—was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study., Work in the UPV laboratories was partly funded by a grant to OV from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution from the European Regional Development Fund.

[EN] We have isolated full-length cDNA clones of the NHX1 gene – encoding the vacuolar Na+ /H+ antiporter – from three Plantago species (P. crassifolia, P. coronopus and P. major) differing in salt tolerance. A phylogenetic tree of their deduced protein sequences and those of NHX1 antiporters previously isolated from other species suggested the presence of some structural features characteristic of the proteins of salt tolerant taxa. The expression patterns of the NHX1 genes in the presence of salt correlated with the relative degree of salt tolerance of the three species: no induction was detected in the least tolerant P. major – and in the glycophyte A. thaliana – and the highest and quickest induction was observed in the most tolerant P. crassifolia. These data support the hypothesis that the NHX1 antiporters play a functional role in the mechanisms of salt tolerance in plants.