Growth temperature control of the linoleic acid content in safflower (Carthamus tinctorius) seed oil

The temperature and oxygen regulation of the microsomal oleate desaturase (FAD2) from safflower (Carthamus tinctorius L.) seeds was investigated. Heat-resistance profiles obtained in vivo and in vitro showed that the FAD2 enzyme maintained its maximal activity until 30 degrees C. A temperature increase from 10 to 40 degrees C caused a decrease of the FAD2 activity. However, when the temperature was decreased from 40 to 10 degrees C, no increase in the activity level was detected. The removal of hulls from safflower seeds followed by incubation in air did not change the FAD2 activity level, whereas incubation under nitrogen caused a strong decrease. Air replacement brought about the recovery of the initials levels. Oxygen concentrations less than 3% produced the inactivation of the enzyme. These data indicate that the higher thermal stability and the lower dependence on oxygen availability of the safflower FAD2 enzyme, compared with that of sunflower, could be the main factors to explain why the linoleate content of safflower seeds is more independent of growth temperature than that of sunflower seeds.     

Structural carbohydrate differences and potential source of dietary fiber of onion (Allium cepa L.) tissues.

Onion tissues of three varieties were evaluated for dietary fiber (DF) composition. Insoluble (IDF) and soluble (SDF) dietary fibers were subjected to acid hydrolysis, and the resultant neutral sugars, uronic acids, and Klason lignin were quantified. Brown skin exhibited the highest total dietary fiber (TDF) content (65.8%) on a dry matter basis, followed by top (48.5%) and bottom (38.6%), IDF being the main fraction found. The SDF:IDF ratio decreased from inner to outer tissues. Brown skin and outer leaves byproducts appear to be the most suitable sources of DF that might be used in food product supplementation. The chemical composition reveals that cellulose and pectic polysaccharides were the main components of onion DF in all tissues, although differences between them were noticed. An increase in the uronic acids/neutral sugars ratio from inner to outer tissues was found, suggesting that the galactan side chain shows a DF solubilization role.     

Effect of heat-inactivated fish and non-fish derived probiotics on the innate immune parameters of a teleost fish (Sparus aurata L.)

The in vitro effects of four heat-inactivated bacterial species on the cellular innate immune responses of the gilthead seabream (Sparus aurata L.) were investigated. Head-kidney leucocytes were isolated and incubated for 30 min with two bacteria isolated from seabream skin (Pdp11 and 51M6; members of the Vibrionaceae and in the genus Shewanella) and two bacteria used as probiotics in humans and cattle (Lactobacillus delbrüeckii subsp. lactis and Bacillus subtilis) at 5 x 10(5), 5 x 10(6) or 5 x 10(7)CFU/ml. After incubation, different cellular innate immune parameters (leucocyte peroxidase content, phagocytosis, respiratory burst activity and cytotoxicity) were evaluated. The leucocyte peroxidase content was significantly higher after incubation with 51M6 at 5 x 10(7)CFU/ml. Head-kidney phagocytes were able to engulf the four bacterial species in all four cases, L. delbrüeckii subsp. lactis and B. subtilis being the most actively phagocytized. The incubation of seabream leucocytes with 51M6, L. delbrüeckii subsp. lactis and B. subtilis resulted in a great increase in respiratory burst activity. Cytotoxic activity was generally stimulated in a dose-dependent manner, the enhancement obtained with 5 x 10(7)CFU/ml being statistically significant. The usefulness of in vitro assays for screening and selecting candidate probiotic bacteria, as well as for optimising their effective dose, is discussed in relation with their immune-modulatory properties.     

Historical and Modern Disturbance Regimes,Stand Structures,and Landscape Dynamics in Piñon–Juniper Vegetation of the Western United States

Piñon–juniper is a major vegetation type in western North America. Effective management of these ecosystems has been hindered by inadequate understanding of 1) the variability in ecosystem structure and ecological processes that exists among the diverse combinations of piñons, junipers, and associated shrubs, herbs, and soil organisms; 2) the prehistoric and historic disturbance regimes; and 3) the mechanisms driving changes in vegetation structure and composition during the past 150 yr. This article summarizes what we know (and don't know) about three fundamentally different kinds of piñon–juniper vegetation. Persistent woodlands are found where local soils, climate, and disturbance regimes are favorable for piñon, juniper, or a mix of both; fires have always been infrequent in these woodlands. Piñon–juniper savannas are found where local soils and climate are suitable for both trees and grasses; it is logical that low-severity fires may have maintained low tree densities before disruption of fire regimes following Euro-American settlement, but information is insufficient to support any confident statements about historical disturbance regimes in these savannas. Wooded shrublands are found where local soils and climate support a shrub community, but trees can increase during moist climatic conditions and periods without disturbance and decrease during droughts and following disturbance. Dramatic increases in tree density have occurred in portions of all three types of piñon–juniper vegetation, although equally dramatic mortality events have also occurred in some areas. The potential mechanisms driving increases in tree density—such as recovery from past disturbance, natural range expansion, livestock grazing, fire exclusion, climatic variability, and CO₂ fertilization—generally have not received enough empirical or experimental investigation to predict which is most important in any given location. The intent of this synthesis is 1) to provide a source of information for managers and policy makers; and 2) to stimulate researchers to address the most important unanswered questions.     

Influence of forest cover and herbaceous vegetation on the microbiological and biochemical properties of soil under Mediterranean humid climate

The effects of different Mediterranean vegetation cover on the biological and biochemical quality of soil is not well understood. The aim of this work is to evaluate the effects that different types of vegetation (forestry plots, mainly dominated by Spanish black pine (Pinus nigra Arn. ssp salzmannii) and herbaceous plots, where overstorey density is lower and natural herbaceous percentage is higher than in forestry plots) have in the biological properties of soil in Mediterranean humid climate. The impact of these plant communities on the biological soil quality was determined by several sensitive parameters related to the microbial activity of the soil such as soil respiration and some enzyme activities (urease, phosphatase and dehydrogenase). Development of vegetation (herbaceous and pines) was also determined and correlated with microbiological and biochemical indicators. Organic matter content in herbaceous sites was significantly higher than in forestry sites, ranging from 5.27 to 6.70 g 100 g^?1 in herbaceous sites to 1.64–2.81 g 100 g^?1 in forested areas. Herbaceous sites showed higher values of basal respiration and dehydrogenase activity than pine areas. However, the decrease of organic carbon content in pine areas led microbial activity enrichment per unit of carbon. These results conclude that vegetation cover significantly impacts soil microbial processes in Mediterranean humid climates, herbaceous vegetation having a more positive influence than forest vegetation on the biochemical and microbial activity of the soil, principally due to the higher accumulation of organic matter from plant remains.     

Development of natural waxes dispensers for pheromones and use in mating disruption of the ambrosia beetle <Emphasis Type="Italic">Megaplatypus mutatus</Emphasis> in poplar (<Emphasis Type="Italic">Populus</Emphasis> spp) plantations

Megaplatypus mutatus (= Platypus mutatus) (Chapuis) is an ambrosia beetle native to South America that attacks live trees, mining deeply into the xylem through large tunnels. This activity weakens the structural integrity of the tree, causing severe stem-breakage and mortality. Attacks are initiated by pioneer males that select a host tree and build short nuptial galleries, to which they attract females using a sexual pheromone. Previously, we showed the potential for the strategy of pheromone-mediated mating disruption of M. mutatus in commercial poplar and hazelnut plantations in South America and Europe using polyethylene reservoir dispensers for pheromones. In the present work we replaced the polymeric reservoir dispensers by monolithic dispensers made by dispersion of the pheromone in natural waxes and the addition of kaolin and we found that: prior to pheromone deployment, the mean number of galleries per tree did not differ significantly between the control and treated plots and the same was observed after the mating disruption treatment for the control plot but not for treated plots, where the mean number of galleries were reduced. These findings confirm that mating disruption is a viable tool for management of M. mutatus in poplar plantations. Using natural wax dispensers has obvious advantages from an environmental point of view.     

Survival and retention of the probiotic properties of Bacillus sp. strains under marine stress starvation conditions and their potential use as a probiotic in Artemia culture

The probiotic properties of Bacillus strains isolated from Artemia culture and the effect of marine stress on viability and survival were investigated, as well as the changes occurring in their properties. Analyses showed that these bacteria corresponded to the genus Bacillus sp. Antagonism and adherence assays revealed that Bacillus strains have an inhibitory effect against tested pathogenic bacteria and are fairly adherent. Normal and starved cells showed different enzymatic profiles. Challenge tests performed with Artemia larvae provided evidence that the tested Bacillus strains were neither pathogenic nor toxic to the host and conferred protection for Artemia culture against pathogens. The tested strains maintained their viability and their probiotic properties during the period of study. The results suggest that the tested strains have suffered changes allowing them to survive in seawater in the absence of nutrients and outside their natural host, identifying them as potential probiotic candidates for Artemia culture.     

Need for speed: Preference for fast‐flowing water by the endangered semi‐aquatic Pyrenean desman (Galemys pyrenaicus) in two contrasting streams

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Immunostimulant properties of a cell wall-modified whole Saccharomyces cerevisiae strain administered by diet to seabream (Sparus aurata L.)

The possible differences in the immunostimulant effects between whole wild Saccharomyces cerevisiae and a mutant strain (fks-1) administered in the diet to gilthead seabream (Sparus aurata L.) were studied. Fish were fed diets containing 0 (control) or 10 g whole wild yeast or fks-1 strain per kilogram feed for 2, 4 or 6 weeks. After each sampling, the innate humoral (complement, lysozyme and peroxidases) and cellular (intracellular peroxidases, phagocytosis, respiratory burst activity and cytotoxicity) responses were determined. Among the humoral responses, serum peroxidases and complement activity were significantly decreased after 6 weeks of feeding with the fks-1 strain-supplemented diet, while lysozyme activity increased after 2 and 4 weeks of feeding the fks-1 strain. Of the cellular responses studied, phagocytosis was increased to a significant degree at all the assayed times but only by the fks-1 strain-supplemented diet, while respiratory burst activity (after 4 weeks) and natural cytotoxicity (after 4 and 6 weeks) increased with either yeast strain. The intracellular peroxidase content was not affected by the dietary supplementation of either yeast strain. These results are discussed with a view to assessing the possible use of wild and/or mutant yeast strains for immunostimulant purposes in aquaculture.