Seasonal and phenological variations of the essential oil from the narrow endemic species Artemisia molinieri and its biological activities

The volatile components of the aerial parts of Artemisia molinieri, an endemic wormwood of southern France, were analyzed by GC and GC-MS. Among the 69 compounds identified, major components were ascaridole (19-76%), alpha-terpinene (traces-36%), p-cymene (1-17%), 1,8-cineole (0.3-8%), and germacrene D (0.6-15%). Quantitative variations have been characterized following the season, the phenological cycle, and the aging of the plants. Bioassays have been performed on a sample of essential oil, which has shown a strong inhibition of the growth of both tested yeasts (Candida albicans and Saccharomyces cerevisiae var. chevalieri) and minor activity on both tested Gram-negative bacteria (Escherichia coli and Enterococcus hirae). The oils have shown interesting antioxidant activities on the basis of alpha-tocopherol as reference compound, up to 400-1200%.     

Trial grow‐out culture of sea cucumber Holothuria scabra in sea cages and pens

Field trials were conducted to determine the effects of size, grow‐out period and site on the growth and survival of Holothuria scabra. Juveniles were reared in sea cages in two sites for 2 months during two different times of the year. Juveniles from Experiment 1 were subsequently grown in sea pens for 8 months in one site. The significantly lower survival particularly of the small‐sized group (<0.1 g) in Pilar is likely due to reduced water and sediment quality because of proximity to fish‐farming activities. The importance of grow‐out period was evident in the significant differences in weight increments in all size groups and biomass in the small‐sized group (P < 0.10) in Lucero during Experiment 2 when water temperature range and incidence of rainfall were higher. The decrease in the average weight of adults during the second half of the grow‐out period may be due to the interplay of the reduction in salinity, onset of sexual maturity and biomass exceeding carrying capacity in the pens. The estimated biomass threshold in the sea cages and pens in Lucero were 300 g m^?2 and 380 g m^?2 respectively. Implications of the results on the viability of small‐scale pen grow‐out culture are discussed.     

Ammonium‐driven nitrification plays a key role in increasing Mn availability in calcareous soils

Background : Manganese deficiency often becomes a yield limiting factor, particularly on calcareous soils, even though the total soil manganese content is usually sufficient. Although it is known that acidifying N fertilizers can improve Mn availability, the reason of this effect is still unknown. Aim : Our aim was to investigate the effect of stabilized ammonium fertilizers as a tool to distinguish between physiological‐ and nitrification‐induced acidification. Method : Two pot experiments with Triticum aestivum L. and one soil incubation experiment using different nitrogen forms (CN = calcium nitrate, AN = ammonium nitrate, AS = ammonium sulfate, ATS = ammonium thiosulfate) with and without addition of nitrification inhibitors (DCD, Nitrapyrin, Piadin, DMPP) were conducted to examine the effect on Mn availability in the soil and Mn uptake by the plants at different development stages (EC 31 und 39). Results : With increasing fertilizer ${\mathrm{NH}}_4^{+}$ content a higher Mn concentration was detected: CN: 32 µg Mn g^?1 DM, AN: 39 µg Mn g^?1 DW, AS: 55 µg Mn g^?1 DM, ATS: 109 µg Mn g^?1 DM. The addition of a nitrification inhibitor resulted in a significantly lower rhizosphere pH compared to the non‐stabilized fertilizer. Surprisingly, the use of different nitrification inhibitors led to unchanged (CN, AN) or lower Mn concentrations of wheat. Especially in the ${\mathrm{NH}}_4^{+}$ treatments (AS and ATS), this negative effect was very evident (AS+DCD: 42 µg Mn g^?1 DM; ATS+DCD: 55 µg Mn g^?1 DM). Conclusions : Mn availability was enhanced by ongoing nitrification process rather than physiological acidification. Compared to other N forms, ammonium thiosulfate led to the highest Mn availability in bulk soil.     

Capacity for digestive hydrolysis and amino acid absorption in Atlantic salmon (Salmo salar) fed diets with soybean meal or inulin with or without addition of antibiotics

This experiment was done to study the effects of dietary soybean meal (SBM) and inulin (a prebiotic) on the capacity for digestive hydrolysis and amino acid absorption by Atlantic salmon, and how a dietary supplement of the broad-spectrum antibiotic oxytetracycline (OTC) modulated these responses. A control diet (FM) was made from fish meal, fish oil and extruded wheat. Two similar diets were made with 250 g soybean meal (SBM) or 75 g inulin kg^− 1. Each diet was made with or without a supplement of 3 g OTC kg^− 1. All six diets contained yttrium oxide for estimation of apparent nutrient absorption. Each diet was fed to two groups of 172 g salmon kept in 1 m² tanks with 9 °C saltwater for 3 weeks. Intestinal organs were then sampled and weighed. Gastrointestinal tracts (GIT) were sectioned for analyses of brush border alkaline phosphatase (ALP) and leucine aminopeptidase (LAP) activities. Tissue from the distal intestine (DI) was also fixed for histological examination. Digesta from the different sections were freeze dried for estimation of trypsin and amylase activities, and of apparent absorption of amino acids (AA), nitrogen (N), and sulphur (S). About 85% of the trypsin activity, 70% of the amylase activity, 85% of the ALP activity, and 82% of the LAP activity were found in the proximal (PI) and mid (MI) intestine of fish with functional DI, and the absorption of AA, N, and S was quantitatively completed in the MI. Dietary OTC resulted in lower relative liver weight, but apart from increased ALP and LAP activities in DI when feeding OTC in combination with inulin, OTC did not modify the responses to dietary SBM or inulin. Dietary SBM resulted in lower relative liver weight, and induced pathomorphological changes in the DI mucosa, thus lower the ALP and LAP activities in the DI. SBM also stimulated absorption of AA, N, and S in the PI, but at the same time increased the activities of trypsin and amylase in the DI, indicating reduced re-absorption and increased faecal losses of these endogenous enzymes. Dietary inulin did not damage the DI, and stimulated intestinal growth and higher relative mass of the GIT. Inulin without OTC did not affect the hydrolytic and absorptive capacity of the salmon GIT.     

Spatial pattern of trees influences species productivity in a mature oak–pine mixed forest

Spatial pattern has a key role in the interactions between species in plant communities. These interactions influence ecological processes involved in the species dynamics: growth, regeneration and mortality. In this study, we investigated the effect of spatial pattern on productivity in mature mixed forests of sessile oak and Scots pine. We simulated tree locations with point process models and tree growth with spatially explicit individual growth models. The point process models and growth models were fitted with field data from the same stands. We compared species productivity obtained in two types of mixture: a patchy mixture and an intimate mixture. Our results show that the productivity of both species is higher in an intimate mixture than in a patchy mixture. Productivity difference between the two types of mixture was 11.3 % for pine and 14.7 % for oak. Both species were favored in the intimate mixture because, for both, intraspecific competition was more severe than interspecific competition. Our results clearly support favoring intimate mixtures in mature oak–pine stands to optimize tree species productivity; oak is the species that benefits the most from this type of management. Our work also shows that models and simulations can provide interesting results for complex forests with mixtures, results that would be difficult to obtain through experimentation.     

Influence of forage harvesting regimes on dynamics of biological dinitrogen fixation of a tropical woody legume

Effects of three forage harvesting regimes-total removal of foliage and branches once (T-12) or twice a year (T-6) and 50% removal every 2 months (P-2)-on growth and biological dinitrogen fixation of Gliricidia sepium (Jacq.) Walp were studied under subhumid tropical conditions in Guadeloupe, French Antilles. Gliricidia sepium was grown in association with the perennial C(4) grass Dichantium aristatum (Poir) C.E. Hubbard in a two-storied fodder production system. The medium-term effects of pruning on N(2) fixation were assessed by the (15)N natural abundance method. Gmelina arborea Roxb. was used as the non-fixing reference. The trees in the T-12 regime followed the natural phenological cycle, and flowering and podfilling at the beginning of the dry season reduced both foliage and nodule biomass. The T-6 regime impeded flowering, and only a few flowers, on older branches, were produced in the P-2 regime. In trees in the T-12, T-6, and P-2 regimes, fixed N comprised 54-87, 54-92, and 60-87%, respectively, of the total N in aboveground biomass, depending on sampling date. Total annual accumulation of N in harvestable aboveground biomass was highest in trees in the T-6 regime at 313 kg ha(-1), of which 204 kg ha(-1) of N was fixed from the atmosphere. In all treatments, about 70% of the N exported per year from the plot in the fodder harvest came from N(2) fixation. Thus, N(2) fixation makes an important contribution to the N economy of the G. sepium-D. aristatum forage production system, and greatly reduces the need for fertilizer application.     

Impact of bark and foliage harvesting on fruit production of the multipurpose tree <Emphasis Type="Italic">Afzelia africana</Emphasis> in Burkina Faso (West Africa)

In sub-Saharan Africa, extraction for daily livelihood needs often results in uncontrolled exploitation of bark and leaves of valuable medicinal and fodder trees. However, overharvesting of bark and foliage can reduce fruit production and threaten reproduction. This study evaluates the impact of combined bark and foliage harvesting on the performance of fruit production of Afzelia africana in Burkina Faso. We compared fruit and seed production at different harvesting intensities. Data on fruit yields were collected by stratified random sampling of 91 trees with no, low, severe, and very severe harvesting intensities. The fruit production varied with harvesting intensity, tree size and number of branches. Fruit and seed quantity and quality decreased with increasing harvesting intensity. However, no significant difference was detected between trees without and trees under low harvesting. Trees of all size classes under very severe harvesting intensity had no fruits. Under low harvesting impact, large trees had twice as many fruits as the control, whereas fruits were reduced by half to 95 % for the small trees. High harvesting intensity is an unsustainable practice that should be completely prohibited in order to ensure longterm persistence of Afzelia africana. Low harvesting intensity should be allowed, but only on large reproductive individuals.     

Induction of T helper type 2 immunity by a point mutation in the LAT adaptor

The transmembrane protein LAT (linker for activation of T cells) couples the T cell receptor (TCR) to downstream signaling effectors. Mice homozygous for a mutation of a single LAT tyrosine residue showed impeded T cell development. However, later they accumulated polyclonal helper T (TH) cells that chronically produced type 2 cytokines in large amounts. This exaggerated TH2 differentiation caused tissue eosinophilia and massive maturation of plasma cells secreting to immunoglobulins of the E and G1 isotypes. This paradoxical phenotype establishes an unanticipated inhibitory function for LAT that is critical for the differentiation and homeostasis of TH cells.     

Phenotypic biodiversity of an endemic wild pear, Pyrus mamorensis Trab., in North-Western Morocco using morphological descriptors

In this paper, we report on morphological diversity, ecology and flowering phenological records of an endangered and an endemic species of Morocco Pyrus mamorensis Trab. For this study, a survey was undertaken in North-Western Morocco (Mamora forest and Zaër region) whereby 67 accessions of P. mamorensis were sampled. A set of 33 genotypes of Pyrus spp. from the international collection INRA-Angers (France) of the genus Pyrus were also analyzed. The variability of the total of 100 accessions was assessed by twenty-six characters including fourteen qualitative and twelve quantitative traits. The results demonstrated high levels of morphological variation in the sampled accessions of P. mamorensis and established the relationships among the local germplasm using the UPGMA cluster analysis and the factorial discriminant analysis. Furthermore, we were able to distinguish three types of flowering in the Mamora forest: early, intermediate and late flowering type. Otherwise, the UPGMA classification comparing local accessions of P. mamorensis to the international collection led to the formation of four major groups showing the closest correspondence to their geographical origins: (1) The North African species represented by P. mamorensis, (2) The East Asian pea species, (3) The West Asian species and (4) The European species. These findings suggest the importance of implementing a conservation strategy preserving the genetic resources of wild pear in North-Western Morocco.