Transport,anoxia and end-product accumulation control carbon dioxide and methane production and release in peat soils

Anaerobic respiration and methanogenesis have been found to slow-down in water saturated peat soils with accumulation of metabolic end-products, i.e. dissolved inorganic carbon (DIC) and methane (CH₄), due to a lack of solute and gas transport. So far it is not well understood how solute and gas transport may control this effect. We conducted a column experiment with homogenized ombrotrophic peat over a period of 300 days at 20 °C. We specifically evaluated the effects of diffusive flux as control, downward advective water flux, intensified ebullition by conduit gas transport and diffusive oxygen supply on controlling anaerobic decomposition rates and carbon (C) turnover. To simulate advective flux, water and solutes were recirculated downward through the column after stripping of dissolved gases. We analyzed DIC and CH₄ concentrations, production rates and fluxes, gas filled porosity, oxygen profiles (O₂) and microbial C biomass over time. DIC residence time thereby served as proxy to characterize transport. A slowdown of anaerobic respiration and methanogenesis evolved with the accumulation of the end-products DIC and CH₄ and set in after 150 days. This slow-down was accompanied by a decrease in the distribution of microbial biomass C with depths. Anaerobic DIC and CH₄ production rates were fastest close to the water table and sharply slowed with depth. Accumulation of DIC and CH₄ in the homogeneous peat material throughout the column decreased decomposition constants from about 10^?5 near the surface to 10^?9 year^?1 deeper in the profile. Advective water transport extended the zone of active methanogenesis compared to a diffusive system; experimental enhancement of ebullition had little or no effect as well as strictly anoxic conditions. DIC residence time was negatively correlated to anaerobic respiration suggesting this parameter to be a predictor of anaerobic peat decomposition in peatlands. Overall, this study suggests that burial of peat and accumulation of metabolic end-products effectively slows decomposition and that this effect needs to be considered to explain peat accumulation and the response of peat mineralization rates to changes in environmental conditions.     

Asperula calabra (Rubiaceae) and allied taxa in southern Apennines,Italy

The present work is aimed at studying several Asperula (Rubiaceae) sect. Cynanchicae populations in southern Apennines, Italy, with particular reference to those referred to A. calabra, by employing biometrical methods on macromorphological data. Among other historical misapplications, A. cynanchica subsp. cynanchica seems to be very rare or missing in southern Italy. The enigmatic Asperula calabra, confirmed to be limited to a single mountain population in Calabria, appears to be strictly related to A. aristata subsp. scabra, so we suggest to treat it as a further subspecies of A. aristata. This latter species is otherwise distributed throughout southern Italy with subsp. scabra and subsp. aristata, characterised by slight morphological differences, which are correlated to altitudinal ranges.     

Peptide aptamers:The versatile role of specific protein function inhibitors in plant biotechnology

In recent years,peptide aptamers have emerged as novel molecular tools that have attracted the attention of researchers in various fields of basic and applied science,ranging from medicine to analytical chemistry.These artificial short peptides are able to specifically bind,track,and inhibit a given target molecule with high affinity,even molecules with poor immunogenicity or high toxicity,and represent a remarkable alternative to antibodies in many different applications.Their use is on the rise,driven mainly by the medical and pharmaceutical sector.Here we discuss the enormous potential of peptide aptamers in both basic and applied aspects of plant biotechnology and food safety.The different peptide aptamer selection methods available both in vivo and in vitro are introduced,and the most important possible applications in plant biotechnology are illustrated.In particular,we discuss the generation of broadbased virus resistance in crops, "reverse genetics" and aptasensors in bioassays for detecting contaminations in food and feed.Furthermore,we suggest an alternative to the transfer of peptide aptamers into plant cells via genetic transformation,based on the use of cell-penetrating peptides that overcome the limits imposed by both crop transformation and Genetically Modified Organism commercialization.     

Correlation between the presence of Gonyaulax fragilis (Dinophyceae) and the mucilage phenomena of the Emilia-Romagna coast (northern Adriatic Sea)

The formation of massive amounts of suspended mucilaginous organic matter which periodically affects the Adriatic Sea, has been regarded as a complex physico-chemical phenomenon resulting from the production of extracellular material by phytoplankton. Although the exact cause has remained obscure, the mechanism of its formation has usually been considered to be a long-term process, starting after the late winter-early spring blooms, and involving the participation of various algal species, mainly within the diatom group. In this paper we report on the results of a phytoplankton monitoring programme in northern Adriatic seawaters off the Emilia-Romagna coast of Italy which revealed the constant concomitant presence of the dinoflagellate Gonyaulax fragilis (Schütt) Kofoid and mucilaginous formations. In the early stages of the phenomenon the dinoflagellate was clearly observable by microscopic examination in the mucilage, but as the mucilage aged this alga almost completely decomposed and diatom cells increased in number and became predominant. Although characterized by a slow growth rate in culture, in natural seawater G. fragilis was observed to reach cell densities of up to 7.0×10⁶ cells l⁻¹. The results of this study lead us to propose the hypothesis that the appearance of mucilage in the water column of the Adriatic Sea is the consequence of a seasonal growth of this dinoflagellate favoured by specific environmental circumstances.     

Habitat-Specific Diversity of Borrelia burgdorferi Sensu Lato in Europe, Exemplified by Data from Latvia

The distribution of Borrelia burgdorferi sensu lato genospecies in questing Ixodes ricinus ticks from ecologically distinct habitats in Latvia was analyzed. A significant variation in the frequency of the genospecies across sites was observed, pointing to the importance of the host community in the ecology of Lyme borreliosis.     

Signification paléoécologique des assemblages de diatomées du Messinien dans le bassin de Melilla-Nador (Rif Nord-Oriental, Maroc)

In the Melilla-Nador basin, the diatomites represent one of the main sedimentary components of the Messinian together with reefal carbonate platforms. Two vertical sections were realised in the diatomitic levels from distal platform. Diatom assemblages are for the first time described in this basin. A total of 125 diatom species were determined: 73 centrics and 52 pennates. Significant diatom assemblages defined from the statistical analysis indicate ecological variations concerning diatomitic levels or parts of diatomitic levels. Using the data sets we propose paleoenvironmental models showing the complexity of the ecological interactions. This study point the permanence of opened marine environment, the impulse of cold waters from Atlantic origin, a general decrease in bathymetry in the Messinian marls-diatomitic series, the influence of the carbonate platform progradation and the occurrence of upwelling systems.     

Organization of neuropeptide tyrosine-like immunoreactive system in the brain of the Antarctic fish, Trematomus bernacchii

Antarctic notothenioids have developed unique freezing-resistance adaptations, including brain diversification, to survive in the subzero waters of the Southern Ocean surrounding Antarctica. In this study we have investigated the anatomical distribution of neuropeptide tyrosine (NPY)-like immunoreactive elements in the brain of the Antarctic fish Trematomus bernacchii, by using an antiserum raised against porcine NPY. Perikarya exhibiting NPY-like immunoreactivity were observed in distinct regions of the brain. The most rostral group of immunoreactive perikarya was found in the telencephalon, within the entopeduncular nucleus. In the diencephalon, three groups of NPY-like immunoreactive perikarya were found in the hypothalamus. Two groups of positive cell bodies were found in distinct populations of the preoptic nucleus, whereas the other group was found in the nucleus of the lateral recess. More caudally, NPY immunoreactivity was detected in large neurons located in the subependymal layers of the dorsal tegmentum of the mesencephalon, medially to the torus semicircularis. NPY-like immunoreactive nerve fibres were more widely distributed throughout the telencephalon to the rhombencephalon. High densities of nerve fibres and terminals were observed in several regions of the telencephalon, olfactory bulbs, hypothalamus, tectum of the mesencephalon and in the ventral tegmentum of the rhombencephalon. The distribution of NPY-like immunoreactive structures suggests that, in Trematomus, this peptide may be involved in the control of several brain functions, including olfactory activity, feeding behaviour, and somatosensory and visual information. In comparison with other neuropeptides previously described in the brain of Antarctic fish, NPY is more widely distributed. Our data also indicate the existence of differences in the brain distribution of NPY between Trematomus and other teleosts. In contrast with previous results reported in other fish, Trematomus contains positive fibres in the olfactory bulbs and immunoreactive perikarya in the nucleus of the lateral recess, whereas NPY-immunopositive cell bodies are absent in the thalamus and rhombencephalon, and no NPY immunoreactivity is present in the pituitary. These differences could be related to the Antarctic ecological diversity of notothenioids living at subzero temperatures.