Specific and reversible immobilization of proteins tagged to the affinity polypeptide C-LytA on functionalized graphite electrodes

We have developed a general method for the specific and reversible immobilization of proteins fused to the choline-binding module C-LytA on functionalized graphite electrodes. Graphite electrode surfaces were modified by diazonium chemistry to introduce carboxylic groups that were subsequently used to anchor mixed self-assembled monolayers consisting of N,N-diethylethylenediamine groups, acting as choline analogs, and ethanolamine groups as spacers. The ability of the prepared electrodes to specifically bind C-LytA-tagged recombinant proteins was tested with a C-LytA-β-galactosidase fusion protein. The binding, activity and stability of the immobilized protein was evaluated by electrochemically monitoring the formation of an electroactive product in the enzymatic hydrolysis of the synthetic substrate 4-aminophenyl β-D-galactopyranoside. The hybrid protein was immobilized in an specific and reversible way, while retaining the catalytic activity. Moreover, these functionalized electrodes were shown to be highly stable and reusable. The method developed here can be envisaged as a general, immobilization procedure on the protein biosensor field.

Community attributes determine facilitation potential in a semi-arid steppe

Studies on positive plant–plant relations have traditionally focused on pair-wise interactions. Conversely, the interaction with other co-occurring species has scarcely been addressed, despite the fact that the entire community may affect plant performance. We used woody vegetation patches as models to evaluate community facilitation in semi-arid steppes. We characterized biotic and physical attributes of 53 woody patches (patch size, litter accumulation, canopy density, vegetation cover, species number and identity, and phylogenetic distance), and soil fertility (organic C and total N), and evaluated their relative importance for the performance of seedlings of Pistacia lentiscus, a keystone woody species in western Mediterranean steppes. Seedlings were planted underneath the patches, and on their northern and southern edges. Woody patches positively affected seedling survival but not seedling growth. Soil fertility was higher underneath the patches than elsewhere. Physical and biotic attributes of woody patches affected seedling survival, but these effects depended on microsite conditions. The composition of the community of small shrubs and perennial grasses growing underneath the patches controlled seedling performance. An increase in Stipa tenacissima and a decrease in Brachypodium retusum increased the probability of survival. The cover of these species and other small shrubs, litter depth and community phylogenetic distance, were also related to seedling survival. Seedlings planted on the northern edge of the patches were mostly affected by attributes of the biotic community. These traits were of lesser importance in seedlings planted underneath and in the southern edge of patches, suggesting that constraints to seedling establishment differed within the patches. Our study highlights the importance of taking into consideration community attributes over pair-wise interactions when evaluating the outcome of ecological interactions in multi-specific communities, as they have profound implications in the composition, function and management of semi-arid steppes.

Taller de revistes digitals com a eina didàctica: de l’ensenyament no universitari a la universitat

El novembre de 2014 el CEFIRE d’Alacant organitzà el I Taller d’Intercanvi d’Experiències per a l’elaboració i divulgació de revistes digitals, hereu de la I i II Jornadas de Prensa en los IES de Alicante que es celebraren els anys 2007 i 2011. Aquest taller tingué com a objectius, entre d’altres, divulgar i intercanviar experiències didàctiques relacionades amb revistes digitals entre centres de diversos nivells, afavorir la creació de projectes educatius cooperatius mitjançant les revistes digitals o establir les bases que permeteren la creació d’una xarxa col·laborativa de revistes digitals. A banda de palesar les diverses propostes dels centres escolars i la incorporació de la revista escolar tradicional al món digital, d’aquella experiència, i parant sobretot atenció al darrer dels objectius citat, ha sorgit la xarxa en docència universitària “Taller de revistes digitals com a eina didàctica: de l’ensenyament no universitari a la universitat”, amb l’objectiu d’aprofundir en les possibilitats didàctiques de les revistes digitals tant pel que fa a l’alumnat no universitari com en les diverses titulacions que ofereix la Universitat d’Alacant. A més de compartir experiències i fomentar l’aprenentatge col·laboratiu de l’alumnat i del professorat implicats, aquesta xarxa en docència universitària vol articular-hi un espai digital permanent en que es puguen recopilar les revistes digitals dels diversos centres educatius.