Influence de la concentration de la solution nutritive dans la phase de réinsertionin vivo des vitroplants d'Erica × darleyensis

Résumé La réinsertion de vitroplants d'Erica × darleyensis est suivie en chambre climatisée et sur perlite arrosée de solutions nutritives, en analysant pendant deux mois le développement des plantes. Quatre solutions nutritives ont été testées. Seule en varie les concentrations (A, A/2, A/4 et A/10); le rapport entre les différents éléments reste constant. Les vitroplants issus d'un milieu de multiplication gélosé A/2, transplantés sur les milieux de réinsertion subisent un choc nutritionnel: même les vitroplants transférésin vivo sur solution dont la concentration en macroéléments est le double de celle du milieu de multiplicationin vitro, enregistrent une diminution des teneurs minérales. L'influence de la nature des substrats de ces différents milieux (gélose ou perlite) semble prédominante à cet égard. Des milieux de réinsertion moyennement concentrés (A/2 ou A/4) constituent les meilleures références pour la précocité et l'optimisation de la production des rameaux. La production des rameaux est reliée à certains paramètres internes nutritionnels tels que: rapports élevés K⁺/(Ca²⁺+Mg²⁺) et Mn²⁺/Fe³⁺, et de hautes teneurs en azote et phosphore.

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Influence ofin vivo nutrient concentration inErica × darleyensis vitroplant transfer on perlite mediaI. Development and nutrient contents of transferred vitroplants

Development ofErica × darleyensis vitroplants was studied on perlite nutritive media in growth chamber conditions, during two months. Four nutritive solutions were examined. Only solution concentrations vary (solutions A, A/2, A/4 and A/10); the ratio between nutrients remains constant. Vitroplants from a A/2 agar-agar propagation medium, transferred on perlite media underwent a nutritional stress: even vitroplants transferred on a perlite medium whose concentration is twice that of the propagation medium, show a decrease in mineral content. The influence of the kinds of substrates (agar-agar or perlite) seems to be prevailing in this respect. Perlite media irrigated with mildly concentrated solutions (A/2 or A/4) are the best references for earliness and optimization of ramification. Branch production is correlated to internal nutritional parameters such as: high K⁺/(Ca²⁺+Mg²⁺) and Mn²⁺/Fe³⁺), a high nitrogen and phosphorus contents.

     

Effects of high hydrostatic pressures on the activity of the membrane ATPases of some organs implicated in hydromineral regulation.

1. The effects of high hydrostatic pressures have been studied on the ATPases extracted from tissues implicated in iono- and osmoregulation of a frog and various teleostean fishes. Pressure affects enzyme activity in the same qualitative way, whatever the tissue and the species considered. 2. The Mg2+ ATPase activity is maximally enhanced at 250 kg/cm2. A slight inhibition is observed at higher pressures up to 1000 kg/cm2. 3. The (Na+ + K+)ATPase is little affected by low pressures but strongly inhibited at 500 kg/cm2 and more. 4. The results are discussed in terms of pressure effects on the recently described protein-lipid interaction linked to ATPase activity.     

Evaluation of an electronic nose for the early detection of organic overload of anaerobic digesters

This study aimed at analysing the utilization of an electronic nose (e-nose) to serve as a specific monitoring tool for anaerobic digestion process, especially for detecting organic overload. An array of non specific metal oxide semiconductor gas sensors were used to detect process faults due to organic overload events in twelve 1.8-L anaerobic semi-continuous reactors. Three different load strategies were followed: (1) a cautious organic load (1.3 gVS L^?1 day^?1); (2) an increasing load strategy (1.3–5.3 gVS L^?1 day^?1) and (3) a cautious organic load with load pulses of up to 12 gVS L^?1 day^?1. A first monitoring campaign was conducted with three different substrates: sucrose, maize oil and a mix of sucrose/oil during 60 days. The second campaign was run with dry sugar beet pulp for 45 days. Hotelling’s T ² value and upper control limit to a reference set of digesters fed with a cautious OLR (1.3 gVS L^?1 day^?1) was used as indirect state variable of the reactors. Overload situations were identified by the e-nose apparatus with Hotelling’s T ² values at least four times higher in magnitude than the upper control limit of 23.7. These results confirmed that the e-nose technology appeared promising for online detection of process imbalances in the domain of anaerobic digestion.     

C, N, P concentrations and requirements of flowering Posidonia oceanica

The carbon, nitrogen and phosphorus contents in flowering and nonflowering shoots were compared after an important flowering event occurred in the Posidonia meadow of the Bay of Calvi. The flower formation caused a significant increase of C and a significant decrease of N concentrations in intermediate and adult leaves. Minimum daily requirements in mgshoot^-1day^-1 of 3.4 and 4.8 of C, 0.09 and 0.09 N, 0.01 and 0.02 of P respectively for nonflowering and flowering shoots were calculated. It shows that additional quantities of C and P are required for the inflorescence elaboration. The unchanged quantity of N required by the shoot for the inflorescence elaboration and the significant modification of N concentration in intermediate and adult leaves suggests that N is limited in the environment and that an efficient resorption of N occurs from leaves to ensure the inflorescence formation.     

Infliximab concentration monitoring improves the control of disease activity in rheumatoid arthritis

Introduction  

Adjustment of infliximab dosage for individuals may be useful in improving therapeutic response in rheumatoid arthritis (RA). Herein, we aimed to determine whether measurement of infliximab serum concentration modifies the therapeutic decision and improves the control of disease activity.     

Expression of VP7, a Bluetongue Virus Group Specific Antigen by Viral Vectors: Analysis of the Induced Immune Responses and Evaluation of Protective Potential in Sheep

Bluetongue virus (BTV) is an economically important Orbivirus transmitted by biting midges to domestic and wild ruminants. The need for new vaccines has been highlighted by the occurrence of repeated outbreaks caused by different BTV serotypes since 1998. The major group-reactive antigen of BTV, VP7, is conserved in the 26 serotypes described so far, and its role in the induction of protective immunity has been proposed. Viral-based vectors as antigen delivery systems display considerable promise as veterinary vaccine candidates. In this paper we have evaluated the capacity of the BTV-2 serotype VP7 core protein expressed by either a non-replicative canine adenovirus type 2 (Cav-VP7 R⁰) or a leporipoxvirus (SG33-VP7), to induce immune responses in sheep. Humoral responses were elicited against VP7 in almost all animals that received the recombinant vectors. Both Cav-VP7 R⁰ and SG33-VP7 stimulated an antigen-specific CD4⁺ response and Cav-VP7 R⁰ stimulated substantial proliferation of antigen-specific CD8⁺ lymphocytes. Encouraged by the results obtained with the Cav-VP7 R⁰ vaccine vector, immunized animals were challenged with either the homologous BTV-2 or the heterologous BTV-8 serotype and viral burden in plasma was followed by real-time RT-PCR. The immune responses triggered by Cav-VP7 R⁰ were insufficient to afford protective immunity against BTV infection, despite partial protection obtained against homologous challenge. This work underscores the need to further characterize the role of BTV proteins in cross-protective immunity.