Ecological conditions for Saxifraga hirculus in Central Europe: A better understanding for a good protection

Saxifraga hirculus is a postglacial relict in Central Europe, whose populations suffered a dramatic decrease in the 19th and 20th centuries. However, few researchers have been interested in its ecological requirements in Central Europe. This article synthesizes previous knowledge supplemented by original data from the last large population (Switzerland).S. hirculus is a weak competitor which needs precise ecological conditions. It grows on bryophyte carpets in neutral to slightly acid wetlands, with stable water table close to the soil surface (optimum between 8 and 14 cm) but does not stand long flooding. However, it requires a good oxygen supply, with roots 2-3 cm under the soil surface, generally not reached by water, with running, cold water through loose, fibric peat. Its optimal conditions are in spring fens, but it grows in other types of wetlands as well. However, overgrowing by shrubs, sedges or Sphagnum in natural successions may threaten the species with extinction, as did drainage and peat extraction previously. Now, its survival in Central Europe depends on an adequate management of the ecosystems. Moderate grazing (cattle or sheep) or mowing help to limit competition with taller Carex species. Reintroduction of disappeared populations or creation of new ones from cultivation in botanical garden is possible, but appropriate sites are rare. In some cases, substrate management could improve the conditions in somewhat inadequate situations. This management in four directions can be flexibly applied in different situations to progress to optimal conditions for the conservation of this valuable species.     

Genetic relationships of alternative somatic cell count traits with milk yield,composition and udder type traits in Italian Jersey cows

The aim of this study was to estimate genetic associations between alternative somatic cell count (SCC) traits and milk yield, composition and udder type traits in Italian Jersey cows. Alternative SCC traits were test‐day (TD) somatic cell score (SCS) averaged over early lactation (SCS_150), standard deviation of SCS of the entire lactation (SCS_SD), a binary trait indicating absence or presence of at least one TD SCC >400,000 cells/ml in the lactation (Infection) and the ratio of the number of TD SCC >400,000 cells/ml to total number of TD in the lactation (Severity). Heritabilities of SCC traits, including lactation‐mean SCS (SCS_LM), ranged from 0.038 to 0.136. Genetic correlations between SCC traits were moderate to strong, with very few exceptions. Unfavourable genetic associations between milk yield and SCS_SD and Infection indicated that high‐producing cows were more susceptible to variation in SCC than low‐producing animals. Cows with deep udders, loose attachments, weak ligaments and long teats were more susceptible to an increase of SCC in milk. Overall, results suggest that alternative SCC traits can be exploited to improve cow's resistance to mastitis in Italian Jersey breed.     

Evaluation of conditions for in vitro storage of commercial and minor grapevine (Vitis vinifera L.) cultivars

In vitro culture represents a tool for the ex situ conservation of a high number of sanitised plants in a reduced space. However, the culture media and/or other growing conditions need to be optimised to minimising plant growth and storage cost. Growth on MW medium was evaluated in the commercial cultivars ‘Airén’, ‘Bobal’, ‘Chardonnay’, ‘Garnacha Blanca’, ‘Moscatel de Alejandría’, ‘Moscatel de Grano Menudo’, ‘Pedro Ximénez’, ‘Pinot Blanc’, ‘Pinot Gris’, ‘Sauvignon Blanc’, and ‘Tempranillo’; the minor cultivars ‘Chelva’, ‘Valencí Negre’, ‘Valencí Blanc’, and ‘Verdil’; and the endangered cv. ‘Esclafacherre’. Different growth rates were observed among cultivars: those with faster growth need to be subcultured every 1.5–2.0 months; those with the slowest growth every 3.5–4.0 months. The effect of halving the sucrose in MW reduced the growth of the cultivars that grew faster without compromising survival. When IBA was removed from MW, growth was also reduced in some cultivars. Therefore, small modifications of the MW composition are adequate for grapevine in vitro storage under standard incubation conditions. This is an advantage with respect to the change of temperature used in other work to achieve growth reduction, and allows the use of the same chamber for different in vitro culture procedures.     

Interaction of the fungicide mancozeb and Rhizobium sp. in pure culture and under field conditions

Information on the compatibility of Rhizobium sp. with seed-protectant chemicals is controversial because of variations in the methods used and the lack of quantitative data. The present study was conducted to determine the influence of the fungicide mancozeb (ethylenebis-dithiocarbamate), at recommended doses, on the growth, survival and symbiotic properties of Rhizobium sp. infecting peanut plants (Arachis hypogaea) under laboratory and field conditions. The results indicated that mancozeb decreased growth in pure culture by 50% of both Rhizobium sp. USDA 3187 and a strain isolated from peanut nodules. However, no differences were found in peanut seed yields under field conditions. These results suggest that the soil environment could reduce the probability of the direct, harmful effects of mancozeb on bacterial growth. Received: 21 June 1996     

Increased Carbon Stabilization in Australian Ferrosol with High Carbon Saturation Deficit

The concept of carbon (C) saturation implies that soils have a finite capacity to store C in a stable form, depending on their silt + clay content. We hypothesized that the stabilization of added organic C would be low in C saturated soil. We tested experimentally the influence of C saturation deficit on stabilization of added grass residue. We incubated 12 highly weathered, oxic soil samples collected from three contrasting land uses (i.e. cropping, improved pasture, and forest) with grass residue for 8 months. Carbon saturation deficit of the forest soils was lower than pasture and cropping soils. After incubation, we found increases in silt + clay associated C in grass residue treatment positively correlated with C saturation deficit of soils. Our results suggest that stabilization of added C was high in soil with low C saturation level and hence higher C saturation deficit.     

Effects of Echerichia coli lipopolysaccharides and dissolved ammonia on immune response in southern white shrimp Litopenaeus schmitti

The success of penaeid shrimp aquaculture has been limited by endemic and epidemic infectious diseases around the world and shrimp defense mechanisms are a priority for control, prevention, and diagnosis. The lethal dose (LD₅₀) of Escherichia coli lipopolysaccharides was calculated and pathogen injection and dissolved ammonia concentration on immune response were evaluated in southern white shrimp Litopenaeus schmitti. The lethal dose of lipopolysacharides was 3.78 mg kg^− 1 body weight. Injection caused changes in phenoloxidase activity in plasma and nitric oxide and total haemocyte counts within the first 24 h. High concentration of dissolved ammonia caused a decrease in haemocytes by 66% within the first 72 h, when compared to the control. Hemagglutination in plasma was not affected by injection or high concentrations of dissolved ammonia. The results showed that white shrimp recognized the lipopolysacharides and responded to this microbial elicitor, as indicated by a variety of immunological indicators and that increased dissolved ammonia affected the number of circulating haemocytes.     

Microbial Growth Models in Gilthead Sea Bream (Sparus aurata) Stored in Ice

ABSTRACT

This study analyzes microbiological changes in whole, ungutted farmed gilthead sea bream (Sparus aurata) stored for an 18-day period in ice using traditional methods for mesophilic aerobic bacteria, psychrotrophic, Pseudomonas spp., Aeromonas spp., Shewanella putrefaciens, Enterobacteriaceae, sulphide-reducing Clostridium (Clostridia), and Photobacterium phosphoreum in muscle, skin, and gills, evaluating their seasonal differentiation. Two different statistical models were used to analyze microbiological growth. Simultaneously, physicochemical parameters such as the temperature, pH, biological oxygen demand (BOD), total dissolved solids, salinity, ammonia nitrogen, and total phosphorus content of growing waters were analyzed. The results showed that by the end of the storage time, specific spoilage bacteria (SSB) such as Pseudomonas spp., Aeromonas spp., and S. putrefaciens as H₂S-producing bacteria were dominant in sea bream harvested in temperate water in the Canary Islands. Muscle tissue had the least contamination, followed by skin and gills. The values of the analyzed seawater parameters were constant during the four seasons, except that the temperature showed a small difference between winter and summer. Seasonal effects were observed among the fish analyzed, suggesting that the lower levels of contamination detected in winter may have been due to the slight difference observed in water temperature in that season.     

Mercury Partitioning in Surface Sediments of the Upper St. Lawrence River (Canada): Evidence of the Importance of the Sulphur Chemistry

An intensive survey of mercury speciation was performed at a site on the Upper St. Lawrence River near Cornwall, Ontario, Canada with a history mercury contamination in sediments. Surface sediments were collected every 1.50 h. Total mercury (Hg_total), methylmercury (MeHg), organic carbon, inorganic and organic sulphur were determined in the solid fraction. Dissolved Hg_total, MeHg and dissolved organic carbon (DOC) were measured in pore waters. Concentrations of Hg_total in the upper layers (first 5 cm) were high, ranging from 1.42 to 25.8 nmol g^?1 in solids and from 125 to 449 pM in pore waters. MeHg levels were also high, ranging from 4.34 to 34.1 pmol g^?1 in solids and from 40 to 96 pM in pore waters. This amounts to up to 1.4% of Hg_total present as MeHg in solids and 64% in pore waters. A daily pattern for Hg_total was observed in the solid fraction. The MeHg distribution in solids and pore waters was not correlated with Hg_total or DOC_, suggesting that the concentrations of MeHg are probably more influenced by the relative rates of methylation/demethylation reactions in the sediment–water interface. Acid volatile sulphide levels and DOC were inversely correlated with organic sulphur (S_org) levels suggesting that both parameters are involved in the rapid production of S_org. A positive correlation was also observed between Hg_total and S_org in solids (R?=?0.87, p?<?0.01) illustrating the importance of organic sulphur in the retention and distribution of Hg in the solid fraction of the sediments. The results suggest that variations of Hg_total concentrations in Upper St. Lawrence River surface sediments were strongly influenced by the formation/deposition/retention of organic sulphur compounds in the sediment–water interface.     

The potential global distribution of <Emphasis Type="Italic">Chilo partellus</Emphasis>, including consideration of irrigation and cropping patterns

Chilo partellus is a major crop pest in Asia and Africa, and has recently spread to the Mediterranean region. Knowledge of its potential distribution can inform biosecurity policies aimed at limiting its further spread and efforts to reduce its impact in areas that are already invaded. Three models of the potential distribution of this insect have been published, each with significant shortcomings. We re-parameterized an existing CLIMEX model to address some parameter inconsistencies and to improve the fit to the known distribution of C. partellus. The resulting model fits the known distribution better than previous models, highlights additional risks in equatorial regions and reduces modelled risks in wet and extremely dry regions. We bring new insights into the role of irrigation in the potential spread of this invasive insect and compare its potential distribution with the present known distribution of its hosts. We also distinguish regions that are suitable for supporting persistent populations from those that may be at risk from ephemeral populations during favourable seasons. We present one of the first demonstrations of a new capability in CLIMEX to automatically estimate parameter sensitivity and model uncertainty. Our CLIMEX model highlights the substantial invasion risk posed by C. partellus to cropping regions in the Americas, Australia, China, Europe, New Zealand and West Africa. Its broad host range and reported impacts suggest that it should be a pest of significant concern to biosecurity agencies in these presently uninvaded regions.