Specificity of LSU rRNA-targeted oligonucleotide probes for Pseudo-nitzschia species tested through dot-blot hybridisation

In the scope of the development of a microarray PhyloChip for the detection of toxic phytoplankton species, we designed a large series of probes specific against targets in the nuclear large subunit (LSU) rRNA of a range of Pseudo-nitzschia species and spotted these onto the microarray. Hybridisation with rRNA extracted from monoclonal cultures and from plankton samples revealed many cross-reactions. In the present work, we tested the functionality and specificity of 23 of these probes designed against ten of the species, using a dot-blot procedure. In this case, probe specificity is tested against the target region in PCR products of the LSU rRNA gene marker region blotted on nitrocellulose filters. Each filter was incubated with a species-specific oligoprobe. Eleven of the tested probes showed specific responses, identifying seven Pseudo-nitzschia species. The other probes showed non-specific responses or did not respond at all. Results of dot-blot hybridisations are more specific than those obtained with the microarray approach and the possible reasons for this are discussed.     

Spatial pattern of ozone injury in Aleppo pine related to air pollution dynamics in a coastal-mountain region of eastern Spain

In eastern Spain, studies combining the tracking and meso-scale circulations of air pollutants with the evaluation of their effects on plants have been undertaken since 1994. Meso-scale processes are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean area. The first results of these field surveys show that in 1994, 1995 and 1996, the distribution pattern of ozone visual injury (chlorotic mottle) in Pinus halepensis correlated with the penetration of pollutants transported by the sea-breeze into coastal valleys of Castellón (eastern Spain). In this tree species, longer needles are associated with higher chlorotic mottle, and ozone injury seems to be among the factors affecting needle retention and crown transparency.     

Properties and erosional response of soils in a degraded ecosystem in Crete (Greece)

To study desertification processes relating to soil erosion, a climatological and altitudinal gradient from south to north was selected in Crete (Greece) and four locations were selected along the gradient. At the locations precipitation ranged from 1400 mm/year at the highest location to 400 mm/year at the lowest. All locations are affected by the actual land use: intensive grazing, small controlled fires, and abandoned agricultural terraces. Representative soil profiles were described in the field and analyzed in the laboratory, and rainfall simulation experiments in the field measured soil erosion over different soil surfaces and land uses. Data on physical and chemical properties were obtained from the soil profiles and soil hydrology, and erosion data were obtained from the rainfall simulation experiments. Soil aggregation was studied with samples taken from the soil in the rainfall simulation plots and special attention being paid to the aggregate size distribution and the water-stable microaggregation. The interaction between climatological conditions and land use seems to be the main factor controlling soil erosion. This paper describes how the expected erosion along the gradient (from the most humid to the driest site) can be affected and disturbed by specific processes derived from land use.     

Phylogenetic diversity of epibiotic bacteria in the accessory nidamental glands of squids (Cephalopoda: Loliginidae and Idiosepiidae)

Bacterial communities were identified from the accessory nidamental glands (ANGs) of European and Western Pacific squids of the families Loliginidae and Idiosepiidae, as also in the egg capsules, embryo and yolk of two loliginid squid species, and in the entire egg of one idiosepiid squid species. The results of phylogenetic analyses of 16S RNA gene (rDNA) confirmed that several phylotypes of α-proteobacteria, γ-proteobacteria and Cytophaga–Flavobacteria–Bacteroides phylum were present as potential symbiotic associations within the ANGs. Several identified clones were related to reference strains, while others had no known close relatives. Gram positive strains were rare in loliginid squids. Several bacterial groups may play important roles in the function of the ANGs, such as production of the toxic compounds involved in egg protection and carotenoid pigments. Within the eggs, no bacteria were associated with embryo or yolk of Loligo vulgaris and Sepioteuthis lessoniana, but α- and γ-proteobacteria were present in the egg capsules. Most bacterial strains detected in the egg capsules were the same as those found in the ANGs. The cephalopods of temperate regions (European cuttlefishes and the squid L. vulgaris) appear to be associated with one Agrobacterium strain (Agro2) while tropical-subtropical strains (Asian and Australian loliginids) are associated with Silicibacter-related strains, suggesting a biogeographic clustering for the Agrobacterium-like strains.     

Genotoxicity of gold nanoparticles functionalized with indolicidin towards Saccharomyces cerevisiae

The toxic effects of gold nanoparticles surface-functionalized with the antimicrobial peptide indolicidin(Au NPs-indolicidin) towards the yeast Saccharomyces cerevisiae, one of the major eukaryotic model organisms, have been evaluated. Growth and survival,genotoxicity, as measured by comet assay, and expression of the YCA1, an apoptosis indicating gene, following 72 hr exposure of yeast to Au NPs-indolicidin, and to Au NPs and indolicidin alone have been examined. The gold nanoparticles exerted toxicity with DNA damage, accompanied by reactive oxygen species production(ROS), but they do not inhibit yeast growth and viability. Genotoxicity was less pronounced for surface-functionalized nanoparticles, showing that S. cerevisiae is quite resistant to the complex Au NPs-indolicidin.A progressive reduction of the genotoxic effect was observed along 72 hr exposure,presumably due to the activation of DNA repair mechanisms. These findings suggest the occurrence of a physiological protective response of S. cerevisiae towards nanoparticles,thereby providing useful information to the assessment of the environmental impact of metal nanoparticles.     

Instrumental and bio-monitoring of heavy metal and nanoparticle emissions from diesel engine exhaust in controlled environment

In the present article we characterized the emissions at the exhaust of a Common Rail (CR) diesel engine, representative of lightduty class, equipped with a catalyzed diesel particulate filter (CDPF) in controlled environment. The downstream exhausts were directly analyzed (for PM, CO, CO2, O2, HCs, NOx) by infrared and electrochemical sensors, and SEM-EDS microscope; heavy metals were chemically analyzed using mosses and lichens in bags, and glass-fibre filters all exposed at the engine exhausts. The highest particle emission value was in the 7–54 nm size range; the peak concentration rose until one order of magnitude for the highest load and speed. Particle composition was mainly carbonaceous, associated to noticeable amounts of Fe and silica fibres. Moreover, the content of Cu, Fe, Na, Ni and Zn in both moss and lichen, and of Al and Cr in moss, was significantly increased. Glass-fibre filters were significantly enriched in Al, B, Ba, Cu, Fe, Na, and Zn. The role of diesel engines as source of carbonaceous nanoparticles has been confirmed, while further investigations in controlled environment are needed to test the catalytic muffler as a possible source of silica fibres considered very hazardous for human health.