Challenge for macrophages and mast cells of Chelon ramada to counter an intestinal microparasite, Myxobolus mugchelo (Myxozoa).

Thinlip mullet Chelon ramada is the most abundant mullet species found in the Comacchio lagoons (northern Adriatic Sea, Italy). Histological and ultrastructural sections of the intestine of C. ramada showed that over 83% of 48 mullets were infected with the intestinal parasite Myxobolus mugchelo (Myxozoa). In histological sections, plasmodia of M. mugchelo containing mature spores were situated closer to mucosal folds and were surrounded by numerous mast cells (MCs). Mature spores, generally oval in shape, were observed in the paracellular space among the enterocytes or within them. Near the infected epithelial cells, several MCs, rodlet cells and few neutrophils occurred. In intestinal epithelium, large cells resembling macrophages, some with spores of M. mugchelo inside, were observed. These macrophage-like cells were foamy and possessed elongate striated granules. The number of MCs and macrophages in the intestinal epithelium was significantly higher in parasitized fish. In some parasitized intestines, portions of epithelium were displaced by spores, or the spores were observed inside the damaged enterocytes. Immunohistochemical analysis of C. ramada infected or uninfected intestinal tissue revealed the presence of histamine, serotonin (5-HT), leu-enkephalin and inducible-nitric oxide synthase in epithelial macrophages. Several epithelial cells positive to proliferating cell-nuclear antigen were also observed in the proximity of the macrophages. The current study is the first to record the occurrence of intraepithelial macrophages which engulf myxozoan spores. A hypothesis on migration of spores from pancreas via intestinal wall to gut lumen is presented.

Intestinal granular cells of a cartilaginous fish, thornback ray Raja clavata: Morphological characterization and expression of different molecules.

This investigation aims to fill gaps in our understanding of the intestinal immune cells of elasmobranchs. Whole digestive tracts of fifteen thornback ray Raja clavata were provided by a trawl fleet from the Gulf of Asinara (Sardinia, western Mediterranean Sea). Histochemical, immunohistochemical and ultrastructural observations were conducted on the spiral intestine. Three types of granular cells were identified; type I in epithelium, types II and III in lamina propria-submucosa, with each of them containing cytoplasmic granules with different ultrastructural characteristics. Data on size and density of each granular cell type are provided. Immunostaining of intestinal sections showed the reactivity of the granular cells: type I cells were positive for lysozyme, mast cell tryptase and tumor necrosis factor-ɑ based on antibody staining; type III cells were immune-reactive to anti-interleukin 6 antibody, whilst type II cells were negative to all the antibodies used. Comparison of each granular cell type with immune cells of teleosts or mammals and an hypothesis on their nature and function are reported. A potential role for granular cells in intestinal cellular immunity is also discussed with respect to type I and type III cells having similarities to Paneth cells and neutrophils, respectively.

Histochemical and immunohistochemical characterization of rodlet cells in the intestine of two teleosts, Anguilla anguilla and Cyprinus carpio.

Rodlet cells (RC) are characterized by a distinctive cell cortex and conspicuous inclusions named "rodlets." These cells are particularly abundant and large in size in intestine of eels. Histochemical, immunohistochemical and ultrastructural investigations were carried out on European eel Anguilla anguilla and Common carp Cyprinus carpio from Northern Italy. Eight biotinylated lectins were used to probe for specific carbohydrate residues in deparaffinized, hydrated intestinal sections of eel and carp. Five antibodies were tested on intestinal sections of both fish species: inducible nitric oxide synthase (i-NOS), leu-enkephalin, lysozyme, serotonin and tumour necrosis factor-α. Lectin histochemistry revealed rodlet cells (RCs) of the eel intestine to react with two of the eight lectins tested, specifically Concanavalin A (ConA) and Sambucus Nigra Agglutinin (SNA). This contrasted to lectin staining of RCs in the intestine of common carp, where four of the eight lectins showed a positive reaction; Dolichos Biflorus Agglutinin (DBA), Wheat Germ Agglutinin (WGA), SNA and ConA. RCs in eel and carp intestine were immunoreactive with antibodies to lysozyme and i-NOS. The occurrence of the inflammatory peptides lysozyme and i-NOS in RCs of the eel and common carp poses in favour that these cells are involved in the mechanism of defence against pathogens.

Liver of the fish Gymnotus inaequilabiatus and nematode larvae infection: Histochemical features and expression of proliferative cell nuclear antigen.

Histopathological lesions due to third-larval stage of nematode Brevimulticaecum sp. within the liver of a subpopulation of 31 Gymnotus inaequilabiatus from the Pantanal Region (Brazil) were studied with histochemical and immunohistochemical methods. In 93.5% of fish, livers harboured nematode larvae and the intensity of infection ranged from 8 to 293. In livers with highest number of larvae, the hepatic tissue was occupied primarily by the nematodes. Each larva was encircled by focal inflammatory granulomatous reaction. Within the thickness of the granuloma, three concentric layers were recognized: an inner layer of densely packed epithelioid cells, a middle layer of mast cells (MCs) entrapped in a thin fibroblast-connective mesh and an outer layer of fibrous connective tissue with fibroblasts. Epithelioid cells and fibroblasts within the thickness of the granuloma wall were positive for proliferative cell nuclear antigen (PCNA). Moreover, several hepatocytes in infected liver were immunoreactive to PCNA. Occurrence of rodlet cells and MCs in parenchyma, in close proximity to the encysted nematode larvae and near the blood vessel of infected liver, was observed. Macrophage aggregates (MAs) were numerous within the granulomas and scattered in parenchyma of the infected liver. High quantity of haemosiderin was encountered in MAs and hepatocytes of infected liver.

European sea bass gill pathology after exposure to cadmium and terbuthylazine: expert versus fractal analysis.

The objective of this study was to compare expert versus fractal analysis as new methods to evaluate branchial lamellar pathology in European sea bass Dicentrarchus labrax (Linnaeus, 1758) experimentally exposed to cadmium and to terbuthylazine. In particular, guided expert quantitative and fractal analysis were performed on selected images from semithin sections to test possible differences according to exposure class (unexposed, cadmium exposed, or terbuthylazine exposed) and the discrimination power of the two methods. With respect to guided expert quantitative analysis, the following elementary pathological features were assessed according to pre-determined cover classes: 'epithelial lifting', 'epithelial shrinkage', 'epithelial swelling', 'pillar cells coarctation', 'pillar cells detachment', 'channels fusion', 'chloride cells swelling' and 'chloride cells invasion'. Considering fractal analysis, DB (box dimension), DM (mass dimension), Dx (mean fractal dimension) as fractal dimensions and lacunarity from DM and Dx scan types were calculated both from the outlined and skeletonized (one pixel wide lines) images. Despite significant differences among experimental classes, only expert analysis provided good discrimination with correct classification of 91.7 % of the original cases, and of 87.5 % of the cross-validated cases, with a sensitivity of 95.45 % and 91.3 %, respectively, and a specificity of 75 % in both cases. Guided expert quantitative analysis appears to be a reliable method to objectively characterize fish gill pathology and may represent a powerful tool in environmental biomonitoring to ensure proper standardization and reproducibility. Though fractal analysis did not equal the discrimination power of the expert method, it certainly warrants further study to evaluate local variations in complexity or possible multiple scaling rules.

Fish innate immunity against intestinal helminths.

Most individual fish in farmed and wild populations are infected with parasites. Upon dissection of fish, helminths from gut are often easily visible. Enteric helminths include several species of digeneans, cestodes, acanthocephalans and nematodes. Some insights into biology, morphology and histopathological effects of the main fish enteric helminths taxa will be described here. The immune system of fish, as that of other vertebrates, can be subdivided into specific and aspecific types, which in vivo act in concert with each other and indeed are interdependent in many ways. Beyond the small number of well-described models that exist, research focusing on innate immunity in fish against parasitic infections is lacking. Enteric helminths frequently cause inflammation of the digestive tract, resulting in a series of chemical and morphological changes in the affected tissues and inducing leukocyte migration to the site of infection. This review provides an overview on the aspecific defence mechanisms of fish intestine against helminths. Emphasis will be placed on the immune cellular response involving mast cells, neutrophils, macrophages, rodlet cells and mucous cells against enteric helminths. Given the relative importance of innate immunity in fish, and the magnitude of economic loss in aquaculture as a consequence of disease, this area deserves considerable attention and support.

Cutaneous myxidiosis in European eel, Anguilla anguilla (Linnaeus, 1758): histopathology, histochemistry and laminin immunohistochemistry.

Histopathology, histochemistry and immunohistochemistry of the integument of European eel, Anguilla anguilla (Linnaeus, 1758), infected by Myxidium sp. are reported. Skin samples from affected and unaffected eels were dissected, formalin fixed, paraffin embedded, sectioned and stained with H&E, Periodic acid-Schiff's staining method, Alcian Blue 8 GX pH 2.5/Periodic acid-Schiff's and McCallum-Goodpasture's Gram stain. Moreover, immunohistochemistry was performed using a primary polyclonal laminin antibody. Histologically, cysts (diameter 2-3 mm) were observed mainly under the scale pockets, encircled by a thin collagen layer, lined by elongated, flattened fibroblasts and containing bipolar, PAS- and Gram-positive spores with opposite polar capsules. The epidermis stretched by the underlying cyst appeared dysplastic, thinned with a significant reduction in mucous cells number. Only inconsistent and aspecific inflammatory reaction was noted around the cysts at the dermis/epidermis interface. Intense laminin-like protein immunolabel was documented in the plasmodial ectoplasm and related to host anergia. This was the first report of laminin immunolabel in a member of the Myxozoa. Epidermal dysplasia represents likely an aspecific response against the underlying tensile force exerted by the developing parasite cyst, while fibroblast and collagen encapsulation denote a parasite-driven host response protecting, rather than harming, the encircled parasite.

Anguilla anguilla intestinal immune response to natural infection with Contracaecum rudolphii A larvae.

The European eel, Anguilla anguilla, is a major warm-water fish species cultured in North and South Europe. Seventy-one A. anguilla collected between 2010 and 2015 from the Comacchio lagoons were examined. Fish were infected and damaged by larvae (L3) of the nematode Contracaecum rudolphii A, which were encapsulated within the thickness of the intestinal wall and within the external visceral peritoneum (serosa). Conspicuous granulomas, visible at sites of infection, were arranged in a trilayer, formed by a series of concentric whorls. The cells involved in the immune response and their distribution in the granuloma layers were assessed by immunohistochemical, immunofluorescence, and ultrastructural techniques. The outer part of the granuloma contained macrophages, macrophage aggregates, and mast cells (MCs) scattered among fibroblasts. This layer was vascularized, with degranulation of MCs occurring in close proximity to the capillaries. The middle layer was rich in MCs and fibroblasts. The inner layer, closest to the parasite larva, consisted mainly of dark epithelioid cells, some of which were necrotic. Non-necrotic epithelioid cells formed desmosomes between themselves or with fibroblasts. Within the granulomas, numerous cells of different types were positive to proliferative cell nuclear antigen antibody, indicating a high degree of cellular proliferation around the larvae.

Fe3O4/γ-Fe2O3 nanoparticle multilayers deposited by the Langmuir-Blodgett technique for gas sensors application.

Fe3O4/γ-Fe2O3 nanoparticles (NPs) based thin films were used as active layers in solid state resistive chemical sensors. NPs were synthesized by high temperature solution phase reaction. Sensing NP monolayers (ML) were deposited by Langmuir-Blodgett (LB) techniques onto chemoresistive transduction platforms. The sensing ML were UV treated to remove NP insulating capping. Sensors surface was characterized by scanning electron microscopy (SEM). Systematic gas sensing tests in controlled atmosphere were carried out toward NO2, CO, and acetone at different concentrations and working temperatures of the sensing layers. The best sensing performance results were obtained for sensors with higher NPs coverage (10 ML), mainly for NO2 gas showing interesting selectivity toward nitrogen oxides. Electrical properties and conduction mechanisms are discussed.

The use of fractal dimension and lacunarity in the characterization of mast cell degranulation in rainbow trout (Onchorhynchus mykiss).

Fractal analysis is a reliable method for describing, summarizing object complexity and heterogeneity and has been widely used in biology and medicine to deal with scale, size and shape management problems. The aim of present survey was to use fractal analysis as a complexity measure to characterize mast cells (MCs) degranulation in a rainbow trout ex vivo model (isolated organ bath). Compound 48/80, a condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde, was adopted as MCs degranulation agent in trout intestinal strips. Fractal dimension (D), as a measure of complexity, 'roughness' and lacunarity (λ), as a measure of rotational and translational invariance, heterogeneity, in other words, of the texture, were compared in MCs images taken from intestinal strips before and after compound 48/80 addition to evaluate if and how they were affected by degranulation. Such measures were also adopted to evaluate their discrimination efficacy between compound 48/80 degranulated group and not degranulated group and the results were compared with previously reported data obtained with conventional texture analysis (image histogram, run-length matrix, co-occurrence matrix, autoregressive model, wavelet transform) on the same experimental material. Outlines, skeletons and original greyscale images were fractal analysed to evaluate possible significant differences in the measures values according to the analysed feature. In particular, and considering outline and skeleton as analysed features, fractal dimensions from compound 48/80 treated intestinal strips were significantly higher than the corresponding untreated ones (paired t and Wilcoxon test, p < 0.05), whereas corresponding lacunarity values were significantly lower (paired Wilcoxon test, p < 0.05) but only for outline as analysed feature. Outlines roughness increase is consistent with an increased granular mediators interface, favourable for their biological action; while lacunarity (image heterogeneity) reduction is consistent with the biological informative content decrease, due to granule content depletion. In spite of the significant differences in fractal dimension and lacunarity values registered according to the analysed feature (greyscale obtained values were, on average, lower than those obtained from outlines and skeletons; General Linear Model, p < 0.01), the discrimination power between not degranulated and degranulated MCs was, on average, the same and fully comparable with previously performed texture analysis on the same experimental material (outline and skeleton misclassification error, 20% [two false negative cases]; greyscale misclassification error, 30% [two false negative cases and one false positive case]). Fractal analysis proved to be a reliable and objective method for the characterization of MCs degranulation.

Cell types and structures involved in tench, Tinca tinca (L.), defence mechanisms against a systemic digenean infection.

Histopathological and ultrastructural investigations were conducted on 36 tench, Tinca tinca (L.), from Lake Trasimeno (Italy). The gills, intestine, liver, spleen, kidney and heart of 21 individuals were found to harbour an extensive infection of larvae of an unidentified digenean trematode. The eyes, gonads, swim bladder and muscles were uninfected. The parasites in each tissue type were embedded in a granulomatous proliferation of tissue, forming a reactive fibroconnective capsule around each larva. Most of the encysted larvae were metacercariae, in a degenerative state, but on occasion some cercariae were found. Many of the granulomas were either necrotic or had a calcified core. Within the granuloma of each, the occurrence of granulocytes, macrophages, rodlet cells and pigment-bearing macrophage aggregates was observed. Hearts bore the highest parasitic infection. Whilst the presence of metacercariae within the intestine was found positioned between the submucosa and muscle layers, metacercariae in the liver were commonly found encysted on its surface where the hepatocytes in close contact with the granuloma were observed to have electron-lucent vesicles within their cytoplasm. Metacercariae encysting adjacent to the cartilaginous rods of gill filaments were seen to elicit a proliferation of the cartilage from the perichondrium. Rodlet cells, neutrophils and mast cells were frequently observed in close proximity to, and within, infected gill capillaries. Given the degenerated state of most granulomas, a morphology-based identification of the enclosed digeneans was not possible.

Stochastic simulation of successive waves of COVID-19 in the province of Barcelona.

Analytic compartmental models are currently used in mathematical epidemiology to forecast the COVID-19 pandemic evolution and explore the impact of mitigation strategies. In general, such models treat the population as a single entity, losing the social, cultural and economical specificities. We present a network model that uses socio-demographic datasets with the highest available granularity to predict the spread of COVID-19 in the province of Barcelona. The model is flexible enough to incorporate the effect of containment policies, such as lockdowns or the use of protective masks, and can be easily adapted to future epidemics. We follow a stochastic approach that combines a compartmental model with detailed individual microdata from the population census, including social determinants and age-dependent strata, and time-dependent mobility information. We show that our model reproduces the dynamical features of the disease across two waves and demonstrates its capability to become a powerful tool for simulating epidemic events.

Rodlet cell biometry: interspecific and intraspecific variability.

Intraspecific and interspecific variability in rodlet cell size in various tissues of several species of freshwater and marine fish were documented. Differences were attributed mainly to fish species, although tissue type contributed significantly, providing evidence for the presence of rodlet cell morphotypes.

Histo-cytological responses of Dicentrarchus labrax (L.) following mercury exposure.

This work deals with the damaging effects of mercury (Hg concentrations 251, 355, 501 microgl(-1)) on the structure and ultrastructure of gills, liver, intestine and kidney of farmed European sea bass (Dicentrarchus labrax L., 1758) acutely treated for 24 and 48 h. The histoarchitecture of the gills of exposed fish was highly modified due to severe oedema, telangiectasia and secondary lamellar fusion. In hepatocytes and enterocytes hydropic cell swelling, alterations to the endoplasmic reticulum and mitochondria were noted, in addition to an abundance of myelinoid bodies which were frequently encountered following treatment. In the intestine and renal tubules of exposed European sea bass, rodlet cells (RCs) displayed ultrastructural modifications. Statistical analyses were conducted on the number and the size of selected cell types and structures. Following exposure to mercury for 24 and 48 h, the number of chloride cells, RCs and macrophage aggregates were found to have increased significantly in the gills, the intestine and the head kidney.

Influence of mycotoxins on spontaneous contraction in myometrial strips of prepubertal lamb.

The effects of mycotoxin zearalenone and their major metabolites alpha- and beta-zearalenol on spontaneous contractions in isolated lamb uterine smooth muscle were examined. The study was carried out on 20 female prepubertal lambs aged between 45 and 50 days. Myometrial strips were set up in two isolated organ baths (10ml) at 37 degrees C and were exposed to increasing concentrations (10(-11)M-10(-6)M) of these mycoestrogens and results were compared with the effect, at the same concentrations, of natural estrogen 17beta-estradiol. Our findings suggest that mycotoxins and 17beta-estradiol, at nanomolar concentrations, rapidly enhance phasic spontaneous smooth muscle contraction. In particular, zearalenone increases the uterine activity similarly to 17beta-estradiol. On the contrary, its metabolite alpha-zearalenol significantly inhibits myometrial contractility.

Assessment of serum protein fractions in rainbow trout using automated electrophoresis and densitometry.

BACKGROUND: Although rainbow trout (Oncorhynchus mykiss, Walbaum) are one of the most-studied fish, electrophoretic techniques and classification of serum protein fractions have not been standardized, such that clinically useful values are lacking. OBJECTIVE: The aim of the present study was to evaluate preliminarily the serum protein fractions of rainbow trout using automated cellulose acetate electrophoresis and densitometry. METHODS: Serum samples from 25 rainbow trout (Oncorhynchus mykiss, Walbaum) were electrophoresed on cellulose acetate plates and quantified using densitometry. RESULTS: A maximum of 6 fractions were identified and numbered, in order of decreasing mobility, as I, II, III, IV, V, and VI. In 3 of 25 (12%) samples, 6 fractions were identified; in 18 (72%) samples, 5 fractions were identified; and in 4 (16%) samples, 4 fractions were identified. Fractions I, V, and VI were always clearly identifiable, whereas fractions II and IV were frequently fused and indistinguishable from fraction III. The pattern with 5 fractions was the most probable type (chi(2), P<.01). The mean (+/-SEM) protein concentrations of the 6 fractions were I, 0.8+/-0.1 g/dL; II, 0.3+/-0.0 g/dL; III, 1.6+/-0.1 g/dL; IV, 0.3+/-0.1 g/dL; V, 0.6+/-0.0 g/dL; and VI, 0.2+/-0.0 g/dL. Based on comparison of serum and plasma electrophoretic patterns from 8 fish, fibrinogen was found in fraction V. CONCLUSION: Automated cellulose acetate electrophoresis and densitometry appear to be a practical method for estimation of serum protein fractions in rainbow trout.

Cellular alterations in different organs of European sea bass Dicentrarchus labrax (L.) exposed to cadmium.

Specimens of farmed European sea bass (Dicentrarchus labrax L., 1758) were exposed to different cadmium (Cd) concentrations (4.47, 5.63, 7.08 and 8.91 mg l(-1)) for 24 and 48 h. The effects of Cd on numbers of some cell types and structures (i.e., chloride cells, CCs; macrophage aggregates, MAs; rodlet cells, RCs) and on structure and ultrastructure of the main organs (gill, liver, intestine, kidney) were studied with routine process for light and transmission electron microscopy. Following cadmium exposure, the numbers of branchial CCs as well as intestinal and renal RCs increased significantly within 24h. Increase in metal concentration did not affect the magnitude of the numerical increment of the aforementioned cells. Moreover, in treated fish (24 and 48 h) the numbers of MAs in both head kidney and spleen were significantly higher than in control conspecifics, whilst the global area of MAs was less influenced by the acute treatment. In exposed sea bass, all the examined organs exhibited cellular modifications which appeared time- and dose-dependent. The gills showed telangectasia, lamellar fusion, oedema, epithelial lifting and leukocyte infiltration. In the liver, kidney and intestine acute cell swelling and vacuolization were common. Ultrastructurally the alterations observed frequently in hepatocytes, tubular epithelial cells and enterocytes included presence of numerous myelinoid bodies, damaged mitochondria, dilatation of endoplasmic reticulum, high number of lysosomes and autophagolysosomes. In intestinal and kidney tubular epithelia of treated fish, rodlet cells displayed some anomalies like dilatation of nuclear envelope, cytoplasmic vacuolization, presence of myelinoid bodies, rodlets degeneration and extensive discharge activity.

Polycyclic aromatic hydrocarbons in marine organisms from the Adriatic Sea, Italy.

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in bivalves (Mitylus galloprovincialis), cephalopods (Todarodes sagittatus), crustaceans (Nephrops norvegicus) and fish (Mullus barbatus, Scomber scombrus, Micromesistius poutassou, Merluccius merluccius) in several pools coming from the Central Adriatic Sea. These marine organisms were selected because of their multitude, wide distribution and common use in the Italian diet, they were sampled and analyzed during the year 2004. Acenaphthene, benzo(a)pyrene, dibenz(a,h)anthracene, benzo(ghi)perylene and indeno(1,2,3-cd)pyrene showed levels below the instrumental detection limit in all samples. Fluorene, phenanthrene, anthracene, fluoranthene, benz(a)anthracene, benzo(b)fluoranthene and benzo(k)fluoranthene were detected at different concentrations in analyzed samples. Chrysene was detected only in mussels with very low values (average 0.74ngg(-1) wet weight). PAHs composition pattern was dominated by the presence of PAHs with 3-rings (62%) followed from those with 4-rings (37%) and 5-rings (1%). Atlantic mackerel, European hake and blue whiting showed the highest PAH concentrations, ranging from 44.1 to 63.3ngg(-1) wet weight, the group of invertebrate organisms showed a level of contamination about three times lower than those of the vertebrate groups. Mediterranean mussels that did not present very high levels of contamination expressed as sum of PAHs showed one of the highest values of benzo(a)pyrene equivalents (BaPEs). Conversely the latter value was very low in Atlantic mackerel even if this species reported the highest total PAH concentrations. No significant correlation was observed between weight, length and trophic levels and total PAHs.

Effects of experimental terbuthylazine exposure on the cells of Dicentrarchus labrax (L.).

The effects of acute exposure to the herbicide terbuthylazine (3.55, 5.01 and 7.08 mg l(-1)) on the cells of farmed European sea bass, Dicentrarchus labrax L., were investigated by means of light and electron microscopy. In gills of treated fish, the number of chloride cells (CCs) and rodlet cells (RCs) increased significantly within 24 h and 48 h, respectively; the intestine showed the largest increase in RCs linked to treatment and exposure time. In kidney, 24 h exposure induced a significant increase in RCs and the number and global area of macrophage aggregates (MAs). Treated fish displayed cellular and/or ultrastructural alterations in all the organs examined. In the gills necrosis, lamellar and cellular oedema, epithelial lifting, telangectasia, and fusion of secondary lamellae were encountered. The liver presented myelin-like figures, cytoplasmic rarefaction and acute cell swelling of hepatocytes. In both organs, the severity of damage was dose-dependent. In RCs of gills, the intestine and kidney of exposed sea bass, high cytoplasmic vacuolization, myelin-like figures, cristolysis and varying degrees of rodlet degeneration were observed. Extensive rodlet expulsion occurred in the gut lumen. Exposure to terbuthylazine also affected the renal tubular epithelial cells, which exhibited 'blebs'. Damage to the intestinal epithelial cells was also observed.

Surface plamon resonance imaging of DNA based biosensors for potential applications in food analysis.

The adsorption processes of oligonucleotides immobilised onto suitable photolithographic patterned gold substrates have been investigated in aqueous buffer solution by using a home made surface plasmon resonance (SPR) imaging equipment. A rapid self-assembled method for the construction of DNA chips to be used in SPR imaging experiments have been followed. The immobilised DNA molecules (probes) adopted in our SPR experiments anchored to a gold surface via thiol group were 5'thiol-modified containing a (CH(2))(15) tail. The hybridisation processes taking place with its complementary sequence have been observed and characterized by monitoring phenomena by a SPR imaging system. The two analysed oligonucleotides (probes and target) are of interest in plant gene biotechnological application and differing for the presence at the 5'-end of a poly T16 spacer. Dynamic investigation of smallest changes in SPR imaging pictures performed in liquid phase in the presence of DNA complementary probes have been performed. Quantitative information in terms of threshold of sensitivity has been extracted by using a specific images treatment.