Vegetative propagation of twelve fodder tree species indigenous to the Sahel,West Africa

In the Sahel region, many woody species are used as fodder because of their high nitrogen content, especially during the dry season, in contrast to grasses and crop residues. Unfortunately, this resource is being threatened by regular pruning, increasing livestock browsing and impeding their natural regeneration. Therefore, there is a need to find appropriate regeneration options to sustain fodder production. Thus, a series of vegetative propagation experiments were conducted to identify the most appropriate multiplication methods of some of the species used as fodder. This series included testing the effects of naphthalene acetic acid (NAA) and indole butyric acid (IBA) on rooting ability of stem cuttings of 12 species: Afzelia africana, Balanites aegyptiaca, Bauhinia rufescens, Commiphora africana, Faidherbia albida, Ficus gnaphalocarpa, Guiera senegalensis, Kigelia africana, Pterocarpus erinaceus, Pterocarpus lucens, Pterocarpus santalinoides and Terminalia avicennioides. The series also evaluated the impacts of the size (C. africana) and the age (P. erinaceus) of the cuttings on their rooting success. Pterocarpus santalinoides was revealed to be an easy-to-root species, showing a high percentage of rooted cuttings (up to 88±3%), followed by P. erinaceus, P. lucens and B. aegyptiaca (up to 37±4%, 31±5% and 26±6%, respectively), in contrast to A. africana, cuttings of which did not root at all. The application of NAA and IBA enhanced the number of roots and secondary roots per rooted cutting. Large-diameter cuttings (15–20?mm) of deeply planted C. africana gave the highest percentage of rooted cuttings (78.3±4.4%). Tree pruning improved the rooting capacity of cuttings collected from P. erinaceus with one-month resprouts giving the highest percentage of rooted cuttings (50.0±6.7%). These results indicate that P. santalinoides, C. africana, P. erinaceus, P. lucens and B. aegyptiaca are amenable to vegetative propagation as an alternative to sexual propagation.     

Experimental in vitro transmission of Babesia sp. (EU1) by Ixodes ricinus

Babesia sp. (EU1), first characterized in 2003, has been implicated in human cases of babesiosis in Italy, Austria and Germany. It has been identified in roe deer and in its suspected tick vector, Ixodes ricinus, in several European countries. The aim of the present study was to validate the competence of I. ricinus as a vector of Babesia sp. (EU1) via experimental infections. For this purpose, a parasite strain isolated from roe deer was cloned in sheep erythrocytes. After experimental infections, parasite DNA was successfully amplified by PCR in both eggs and larvae originating from infected I. ricinus females and in the salivary glands of females exposed to Babesia sp. (EU1) as nymphs. We also demonstrate that infected females were able to transmit parasite DNA during a new blood meal. Together with previous epidemiological studies, these results validate I. ricinus as a competent vector for Babesia sp. (EU1).     

Effect of nitrogen fertilization on nitrogen dynamics in oilseed rape using 15N‐labeling field experiment

In order to optimize nitrogen (N) fertilization and to reduce the environmental impact of oilseed rape without decreasing yield, a clearer understanding of N dynamics inside the plant is crucial. The present investigation therefore aimed to study the effects of different N‐application rates on the dynamics of N uptake, partitioning, and remobilization. The experiment was conducted on winter oilseed rape (Brassica napus L. cv. Capitol) under three levels of N input (0, 100, and 200 kg N ha^–1) from stem elongation to maturity using ¹⁵N‐labeling technique to distinguish between N uptake and N retranslocation in the plant. Nitrogen fertilization affected the time‐course of N uptake and also the allocation of N taken up from flowering to maturity. Most pod N came from N remobilization, and leaves accounted for the largest source of remobilized N regardless the N‐application rate. However, the contribution of leaves to the remobilized N pool increased with the N dose whereas the one of taproot decreased. Stems were the main sink for remobilized N from stem elongation to flowering. Leaves remained longer on N200 than on N0 and N100 plants, and N concentration in fallen leaves increased with the N treatment and in N100 plants along an axial gradient from the basal to the upper leaves. Overall, these results show that the timing of N supply is more crucial than the N amount to attain a high N efficiency.     

“Aberrant” plants in cauliflower: 2. Aneuploidy and global DNA methylation

Aberrant phenotypes of cauliflower were detected throughout the cultivation period and in any variety type. The rate of these phenotypes in the field has recently increased. We reported previously on the first part of our results which showed that (1) the rate of aberrant plants varied with genotype and cultivation area, (2) the aberrant phenotypes can evolve or reverse to normality during the plant cycle and (3) the capacity to express a variant phenotype can be transmitted to the progeny. An epigenetic hypothesis has been proposed to explain the determinism of the phenomenon. Further investigation on the “aberrant” character focussed on the flow cytometric estimation of ploidy levels and on the parallel observation of meiosis. Only a fraction of aberrant plants did show aneuploidy and various ploïdy levels were found for the same phenotype. Indeed, aneuploidy could not be related to the aberrant phenotype although it could probably be a consequence of the aberration phenomenon. HPLC analysis of global DNA methylation rates showed that DNA hypermethylation occurred in plants which exhibited an evolution of their phenotype during vegetative cycle. The epigenetic origin of aberrant phenotypes in cauliflower is discussed with reference to epigenetic diseases described in human beings.     

Development of a platform of antibody-presenting liposomes

Antibody-presenting liposomes present high interest as drug delivery systems. The association of antibodies to liposomes is usually realized by covalent coupling of IgGs or their antigen-binding fragments to lipid polar head groups by means of hetero-bifunctional crosslinkers. We present here an original platform of IgG-presenting liposomes which is based on a fusion protein between Annexin-A5 (Anx5) and the IgG-binding ZZ repeat derived from Staphylococcus aureus protein A. The Anx5ZZ fusion protein acts as a bi-functional adaptor that anchors IgGs to liposomes in a non covalent and highly versatile manner. The interactions between IgGs, Anx5ZZ and liposomes were characterized by PAGE, dynamic light scattering and fluorescence quenching assays, establishing that binding of Anx5ZZ to IgGs and of Anx5ZZ-IgG complexes to liposomes is complete with stoichiometric amounts of each species. We found that the sequence of assembly is important and that Anx5ZZ-IgG complexes need to be formed first in solution and then adsorbed to liposomes in order to avoid aggregation. The targeting capacity of Anx5ZZ-IgG-functionalized liposomes was demonstrated by electron microscopy on an ex vivo model system of atherosclerotic plaques. This study shows that the Anx5ZZ adaptor constitutes an efficient platform for functionalizing liposomes with IgGs. This platform may present potential applications in molecular imaging and drug delivery.     

Extraction, preparation and characterization of cellulose fibres and nanocrystals from rice husk

Cellulose fibres and cellulose nanocrystals were extracted from rice husk. Fibres were obtained by submitting the industrial rice crop to alkali (NaOH) and bleaching treatments. Nanocrystals were extracted from these fibres using sulphuric acid (H₂SO₄) hydrolysis treatment. The material obtained after each stage of the treatments was carefully characterized and its chemical composition was determined. Morphological investigation was performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) spectroscopy showed the progressive removal of non-cellulosic constituents. X-ray diffraction (XRD) analysis revealed that the crystallinity increased with successive treatments. The thermal stability of the rice husk fibres and cellulose nanocrystals was also investigated using thermogravimetric analysis (TGA).     

GIS Coop: networks of silvicultural trials for supporting forest management under changing environment

Key message

The diversity of forest management systems and the contrasted competition level treatments applied make the experimental networks of the GIS Coop, a nationwide testing program in the field of emerging forestry topics within the framework of the ongoing global changes.

Context

To understand the dynamics of forest management systems and build adapted growth models for new forestry practices, long-term experiment networks remain more crucial than ever.

Aims

Two principles are at the basis of the experimental design of the networks of the Scientific Interest Group Cooperative for data on forest tree and stand growth (GIS Coop): contrasted and extreme silvicultural treatments in diverse pedoclimatic contexts.

Methods

Various forest management systems are under study: regular and even-aged stands of Douglas fir, sessile and pedunculate oaks, Maritime and Laricio pines, mixed stands of sessile oak, European silver fir, and Douglas fir combined with other species. Highly contrasted stand density regimes, from open growth to self-thinning, are formalized quantitatively.

Results

One hundred and eighty-five sites representing a total of 1206 plots have been set up in the last 20 years, where trees are measured regularly (every 3 to 10 years). The major outputs of these networks for research and management are the calibration/validation of growth and yield models and the drawing up of forest management guides.

Conclusion

The GIS Coop adapts its networks so that they can contribute to develop growth models that explicitly integrate pedoclimatic factors and thus also contribute to research on the sustainability of ecosystems under environmental and socio-economic changes.

     

A NOVEL,REMOVABLE, CERROBEND,BEAM‐BLOCKING DEVICE FOR RADIATION THERAPY OF THE CANINE HEAD AND NECK: PILOT STUDY

Radiation therapy of the head and neck can result in mucositis and other acute affects in the oral cavity. This prospective pilot study evaluated a novel, intraoral, beam‐blocking device for use during imaging and therapeutic procedures. The beam‐blocking device was made from a metal alloy inserted into a coated frozen dessert mold (Popsicle® Mold, Cost Plus World Market, Oakland, CA). The device was designed so that it could be inserted into an outer shell, which in turn allowed it to be placed or removed depending on the need due to beam configuration. A Farmer type ionization chamber and virtual water phantom were used to assess effects of field size on transmission. Six large breed cadaver dogs, donated by the owner after death, were recruited for the study. Delivered dose at the dorsal and ventral surfaces of the device, with and without the alloy block in place, were measured using radiochromic film. It was determined that transmission was field size dependent with larger field sizes leading to decreased attenuation of the beam, likely secondary to scatter. The mean and median transmission on the ventral surface without the beam‐blocking device was 0.94 [range 0.94–0.96]. The mean and median transmission with the beam‐blocking device was 0.52 [range 0.50–0.57]. The mean and median increase in dose due to backscatter on the dorsal surface of the beam‐blocking device was 0.04 [range 0.02–0.04]. Findings indicated that this novel device can help attenuate radiation dose ventral to the block in dogs, with minimal backscatter.