Preliminary investigations of hydrogen peroxide treatment of selected ornamental fishes and efficacy against external bacteria and parasites in green swordtails

The objectives of these preliminary studies were to evaluate the use of hydrogen peroxide (H2O2) for the treatment of selected species of ornamental fishes and its efficacy in treating external bacteria and parasites. In the first part of the study, fish of five species (serpae tetra Hyphessobrycon eques (also known as Serpa tetra H. serpae), tiger barb Puntius tetrazona, blue gourami Trichogaster trichopterus, suckermouth catfish Hypostomus plecostomus, and green swordtail Xiphophorus hellerii) were exposed to H2O2 for 1 h at concentrations between 6 and 34 mg/L or for 24 h at concentrations between 1 and 6 mg/L. The results were species specific: green swordtails tolerated all of the treatments, serpae tetras and tiger barbs were sensitive only to the highest concentration, and mortalities of suckermouth catfish and blue gourami were recorded in every treatment. In the second part of the study, clinically healthy green swordtails and fish infested with external motile rod-shaped bacteria (i.e., Ichthyobodo spp., Trichodina spp., and Gyrodactylus spp.) were treated with several concentrations of H2O2. A single H2O2 treatment of 3.1 mg/L or more for 1 h effectively eliminated external bacteria, concentrations of 6.5 mg/L or more appeared to effectively kill Ichthyobodo spp., and none of the treatments tested was effective against Trichodina spp. or Gyrodactylus spp. These preliminary findings suggest that H2O2 is effective for treating certain external bacterial infections and flagellate infestations in some species of ornamental fish at the dosages tested. Other treatment regimens may need to be tested for effectiveness against Trichodina spp. and Dactylogyrus spp.     

Microbial enzyme activities,fungal biomass and quality of the litter and upper soil layer in a beech forest of south Italy

Forest soils contain a large amount of organic matter (OM) and therefore represent a considerable carbon reserve. The amount of OM sequestered in the soil is dependent on annual input of litter and its quality. The aim of this study was to investigate the quantity and quality of OM, the microbial capacity to degrade it and its recalcitrance to further degradation, by considering some extracellular enzyme activities in a beech (Fagus sylvatica L.) forest in south Italy (Mediterranean area). Our attention was focused on the decomposition continuum of the litter horizon and upper soil layer. Because fungi are the major decomposers of plant material, fungal biomass was also measured and its relationship with enzyme activities was tested. The results showed that: (i) the litter horizon and the upper soil layer differed in chemical characteristics and biological activities; (ii) within the litter horizon, the three layers detected for their different degree of degradation (L, recently fallen, not decomposed and not compressed material; F, partially decomposed and fragmented but macroscopically recognizable material; H, compressed and strongly fragmented) differed more in chemical characteristics than in biological activities; (iii) the enzyme activities and fungal biomass changed during the study period but a clear relationship with succession of seasons was evident only for cellulase, laccase, peroxidase and fungal biomass; and (iv) the upper soil layer included 42% OM and less than 50% of that was susceptible to further decomposition. This percentage was 30% in the OM of L.     

Access to technical information and gendered NRM practices: Men and women in rural Senegal

Gender differences in knowledge of NRM practices have long been noted in Senegal and throughout Sub-Saharan Africa. An exploration of these differences among a sample of rural Senegalese men and women shows that these differences are, in part, a function of extension agent interventions. The level of knowledge of a set of NRM technologies is associated with contact with three key types of extension agent in rural Senegal: extension team leaders, forestry agents, and women's agents. Analysis of intra-household variation in levels of knowledge shows a degree of interdependence between the knowledge levels of husbands and wives for some practices. However, multi-variate analysis, controlling for personal and contextual factors, clearly demonstrates the independent impact of extension agents on gender differences in rural Senegalese NRM knowledge. It can be concluded that contact with extension agents increases knowledge of NRM practices. In particular, contact with the women's agent is a strong predictor of the level of women's NRM knowledge and, surprisingly, also contributes to the level of men's knowledge. Despite the small number of women's agents in the field, they appear to have significant positive impact on the dissemination of NRM knowledge among rural Senegalese women and men. This revised version was published online in June 2006 with corrections to the Cover Date.     

Accumulation and erosion of Mars' south polar layered deposits

Mars' polar regions are covered with ice-rich layered deposits that potentially contain a record of climate variations. The sounding radar SHARAD on the Mars Reconnaissance Orbiter mapped detailed subsurface stratigraphy in the Promethei Lingula region of the south polar plateau, Planum Australe. Radar reflections interpreted as layers are correlated across adjacent orbits and are continuous for up to 150 kilometers along spacecraft orbital tracks. The reflectors are often separated into discrete reflector sequences, and strong echoes are seen as deep as 1 kilometer. In some cases, the sequences are dipping with respect to each other, suggesting an interdepositional period of erosion. In Australe Sulci, layers are exhumed, indicating recent erosion.     

Biomedical exploitation of chitin and chitosan via mechano-chemical disassembly, electrospinning, dissolution in imidazolium ionic liquids, and supercritical drying

Recently developed technology permits to optimize simultaneously surface area, porosity, density, rigidity and surface morphology of chitin-derived materials of biomedical interest. Safe and ecofriendly disassembly of chitin has superseded the dangerous acid hydrolysis and provides higher yields and scaling-up possibilities: the chitosan nanofibrils are finding applications in reinforced bone scaffolds and composite dressings for dermal wounds. Electrospun chitosan nanofibers, in the form of biocompatible thin mats and non-wovens, are being actively studied: composites of gelatin + chitosan + polyurethane have been proposed for cardiac valves and for nerve conduits; fibers are also manufactured from electrospun particles that self-assemble during subsequent freeze-drying. Ionic liquids (salts of alkylated imidazolium) are suitable as non-aqueous solvents that permit desirable reactions to occur for drug delivery purposes. Gel drying with supercritical CO(2) leads to structures most similar to the extracellular matrix, even when the chitosan is crosslinked, or in combination with metal oxides of interest in orthopedics.     

Resistance traits and AFLP characterization of diploid primitive tuber-bearing potatoes

Worldwide, a variety of pathogens negatively affect potato production, resulting in an estimated 22% annual yield reduction. Wild Solanum species represent a unique gene pool where all the traits necessary to improve the cultivated potato can be found. Therefore, breeding efforts for improved disease resistance and research aimed at characterizing wild germplasm have been extensively made. In this paper, sources of resistance to Phytophthora infestans, Erwinia carotovora subsp. carotovora, Fusarium solani and Globodera spp. have been investigated in several clones of two Solanum species originating from Central Mexico (S. bulbocastanum and S. cardiophyllum). Interestingly, we found sources of combined resistance to late blight and bacterial soft rot. This is an important finding considering that the development of resistant potato varieties has been hindered by the scarcity of resistant germplasm. In addition, we explored molecular differences within and between the two species generating AFLP fingerprints. By means of six primer pair combinations, we found 13 and 16 putative species-specific AFLP markers for S. bulbocastanum and S. cardiophyllum, respectively, and a bounty of markers useful for mapping, MAS, and cloning purposes. The phenotypic and molecular information associated to S. bulbocastanum and S. cardiophyllum for designing strategies of assisted selection are discussed.     

The barley (Hordeum vulgare L.) of Sardinia, Italy

Since ancient times, barley has been an important food resource for the people of Sardinia. The oldest traces of its cultivation are from the mid-Neolithic (fourth millennium B.C.). Archaeological, historical and anthropological aspects of barley cultivated in Sardinia are discussed in this paper. We describe the traditional process for making barley bread (orgiathu) in Sardinia, where a special starter called ghimisone was prepared. Today, barley is cultivated only as animal feed, with two uses, grain yield and grazing. Many farmers prefer to grow local populations belonging to landrace locally known as S' orgiu sardu. Local Sardinian populations of barley evolved in diverse environments, being cultivated from sea-level up to 1000 m elevation, on various soil types at different intensities of abiotic stresses, and with climates and environments associated with various agricultural practices, depending both on production strategies and climatic conditions. These barley materials are thought to be valuable genetic and cultural inheritance which must be preserved and used for both productive and research purposes.     

Retention of coumaric acid by soil and its colloidal components

In this study of the behavior of coumaric acid added to soil, the disappearance of the acid was found to be due to adsorption plus microbial degradation, and was influenced by the concentration and contact time. Adsorption experiments set up with soils varying widely in their chemical and physical properties, showed that the Freundlich isotherm fits the data quite well and that among the different soil factors, only the pH was closely and negatively correlated with coumaric acid adsorption. Approximately at pH > 7 no adsorption occurred, perhaps due to the repulsion between the negatively charged soil colloids and the dissociated acidic groups of coumaric acid. Adsorption experiments carried out with different adsorbents showed that the hydroxy-Fe compound was the most effective in retaining coumaric acid, followed by humic acid, illite, kaolinite and vermiculite, in this order.     

Fungi-to-bacteria ratio in soils of European Russia

The selective inhibition technique by specific antibiotics (streptomycin, cycloheximide) applied to substrate-induced respiration (SIR) measurement was used to test the relative contribution of fungi to bacteria (F/B ratio) to the overall microflora-induced activity in soils of European Russia. Investigated soils covered a wide climatic transect and different ecosystem types including managed vs. natural ecosystems. Before direct comparison among sites, the antibiotic inhibition technique was optimized for soil characteristics. Once the optimal concentration was set, the combined effect of the two antibiotics resulted in average 60% inhibition of SIR. The analyzed sites (in total 47) including various biomes (tundra, middle taiga, southern taiga, subtaiga, dark coniferous forests outside the boreal region, steppe, mountain forests and arable sites), were characterized by a wide range of soil pH_w (3.95–7.95), soil organic carbon (0.69–24.08%), soil microbial biomass carbon (149–5028 µg C g^?1 soil) and soil basal respiration (0.24–8.28 µg CO₂-C g^?1 soil h^?1). In all the analyzed sites, a predominance of fungal over bacteria activity was observed with F/B ratios always higher than one (4.9 on average). Natural sites were characterized by higher F/B ratios (on average 5.6) compared to agricultural ones (on average 3.5).     

Growth and mineral content of roots and shoots of maize seedlings in response to increasing water deficits induced by peg solutions

Abstract

The effects of polyethylene glycol (PEG) solutions of increasing osmotic potentials (ψπ=?0.44 and ‐0.88 MPa) on the growth of the seedlings and on the concentrations of Mn, Cu, Pb, Zn, Ni, Co, Mo, Cr, Cl, Fe, Ca, Mg, K, Na, P, and N were determined in the shoots and roots of maize (Zea mays L. cv. Summer II) grown in Hoagland's solution in a growth chamber. Water stress was imposed for three days with PEG 4000 on six‐day‐old seedlings. Despite a reduction in the leaf water potential (ψw), which decreased with increasing PEG concentrations, and despite an increase in the water saturation deficit (W.S.D.), the pressure potentials (ψp) were maintained in both treatments at levels quite similar to that in the control seedlings.

At ψπ=?0.44 MPa of the growth medium, both the length and dry weight of the shoots and roots significantly decreased, whereas at ψπ=?0.88 MPa only the root length continued to decrease with the consequence of an increase in the total mass production of the seedlings. At ψπ=?0.88 MPa, PEG was absorbed by the seedlings in significant amounts, although the roots were undamaged.

The effects of the imposed water stress on nutrient absorption and accumulation differed in the two treatments, depending on the plant tissue and nutrient; nevertheless, the element contents generally showed their lowest values at ψπ=?0.44 MPa, as consequence of the reduction in dry matter. The water stress experienced by the maize seedlings grown at ψπ=?0.88 MPa did not induce further decreases in either the macro‐ or micronutrients.