Abstract. Question: How do properties of different vegetation components vary along ecotones of semi‐deciduous forest islands, and can the depth of edge influence (DEI) of the components be detected using a novel combination of analyses? Location: Comoé National Park (CNP), NE Ivory Coast. Methods: Along eight transects at semi‐deciduous forest islands tree individuals > 20 cm DBH were mapped. At one transect, tree and shrub individuals down to 1 cm DBH were measured and cover of species was estimated. Split moving window dissimilarity analysis (SMWDA) and moving window regression analysis (MWRA) were combined to detect statistical significance of borders in multivariate vegetation data along continuous transects, to determine the width of associated ecotones, and, thus, the DEI towards the forest interior. Results: For trees > 20 cm DBH, a distinct boundary formation was detected, dominated by the semi‐fire resistant tree species Anogeissus leiocarpus. The median of DEI towards the forest interior was 55 m. Ecotone detection with all species present revealed an interlocked sequence of ecotones for grasses, herbs, woody climbers, shrubs and trees, with each of these ecotones being narrower than the overall ecotone. DEI ranged from 10 m for grasses up to 120 m for trees and shrubs. Conclusions: The coherent set of analyses applied proved to be an objective method for detecting borders and the width of associated ecotones. The patterns found may be explained by successional processes at the forest‐savanna border. The DEI measured for the forest islands in the nearly undisturbed semi‐natural system of the CNP is of relevance to concepts of core‐area analysis and the protection of forest interior species in semi‐deciduous forests in tropical West Africa.

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A β-glucosidase was purified from the digestive fluid of the palm weevil Rhynchophorus palmarum L. (Coleoptera: Curculionidae) by chromatography on anion-exchange, gel filtration, and hydrophobic interaction columns. The preparation was shown to be homogeneous on polyacrylamide gels, β-glucosidase is a monomeric protein with a molecular weight of 58 kDa based on its mobility in SDS-PAGE and 60 kDa based on gel filtration. Maximal β-glucosidase activity occurred at 55°C and pH 5.0. The purified β-glucosidase was stable at 37°C and its pH stability was in the range of 5.0–6.0. The enzyme readily hydrolyzed p-nitrophenyl-β-D-glucoside, cellobiose, cellodextrins and required strictly β-gluco configuration for activity. It cleaved glucose-glucose beta-(1–4) linkages better than β-(1–2), β-(1–3) and β-(1–6) linkages. The catalytic efficiency (Kcat/KM) values for p-nitrophenyl-β-D-glucoside and cellobiose were respectively 240.48 mM-1s-1 and 134.80 mM-1s-1. Beta-glucosidase was capable of catalysing transglucosylation reactions. The yield of glucosylation of 2-phenylethanol (20 %), catalysed by the beta-glucosidase in the presence of cellobiose as glucosyl donor, is lower than those reported previously with conventional sources of beta-glucosidases. In addition, the optimum pH is different for the hydrolysis (pH 5.0) and transglucosylation reactions (pH 6.6).

Two b-glycosidases were purified from the termite Macrotermes subhyalinus (Rambur) workers by chromatography on gel filtration, ion exchange and hydrophobic interaction columns. The preparations were shown to be homogeneous on polyacrylamide gel. Both enzymes have a similar molecular mass (68 KDa) and optimum pH (5.4) but differ in optimal temperature and thermal stability. The b-glycosidases preferred b-fucosides to b-glucosides, b-galactosides and b-xylosides, and hydrolysed glucoseglucose-b-(1 -4) linkages better than b-(1 -3), b-(1 -2) and b-(1 -6) linkages. They did not hydrolyse saccharides such as melibiose, sucrose, lactose, xylobiose, melizitose, stachyose, lactose, raffinose, laminarin, arabinogalactan, carboxymethylcellulose, inulin, lichenan and starch. b-Glycosidase A and b-glycosidase B of M. subhyalinus workers are capable of catalysing transglucosylation reactions. The yields of glucosylation of hydroxyamino acid derivatives and phenylethanol, catalysed by the two enzymes in the presence of cellobiose as glucosyl donor, were lower than those reported previously with conventional sources of b-glycosidases. In addition, the optimum pH is different for the hydrolysis and transglucosylation reactions.On the basis of this work, it is proposed that the physiological role of b-glycosidase A and b-glycosidase B of M. subhyalinus workers is the digestion of di-and oligosaccharides derived from hemicelluloses and celluloses. q ICIPE 2005 les réactions de transglucosylation. Les rendements des réactions de glucosylation des dérivés d'hydroxyaminoacides et du phényléthanol, en présence de cellobiose comme donneur de glucosyle, sont plus faibles que ceux rapportés par les sources conventionnelles de glycosidases. De plus, les pH optimums d'hydrolyse et de transglycosylation sont différents.A partir de ces résultats, nous pouvons dire que le rô le physiologique des bglycosidases A et B de l'ouvrier du termite M. subhyalinus est de digérer les di et oligosaccharides provenant des hémicelluloses et des celluloses.