Host cell invasion by apicomplexan parasites: the junction conundrum

No abstract available

Test of several approaches for the composition of web services in meteorology.

International audienceComposition of web services is a powerful means to answer user needs in many domains. This communication focuses on applications in meteorology. This domain presents several particularities which are discussed. We present an overview of three main types of approaches in composition of web services: static plan, IA-plan and theorem proof. We confront these types of approaches to the specific case of meteorology which is not well studied by the research community in web services. We design a test bed that is capable of handling the key issues in meteorology. We have selected three approaches. We adapt them to our case and build three prototypes which are used in the test bed to point out weakness and strength of each approach. We find that current approaches do not fulfill needs in meteorology. We recommend an hybrid approach that combines the three in order to obtain an automatic and adaptative composition

Substrate specificity of the streptococcal cysteine protease.

The streptococcal pyrogenic exotoxin B (SpeB) is an important factor in mediating Streptococcus pyogenes infections. SpeB is the zymogen of the streptococcal cysteine protease (SCP), of which relatively little is known regarding substrate specificity. To investigate this aspect of SCP function, a series of internally quenched fluorescent substrates was designed based on the cleavage sites identified in the autocatalytic processing of SpeB to mature SCP. The best substrates for SCP contain three amino acids in the nonprimed position (i.e. AIK in P(3)-P(2)-P(1)). Varying the length of the substrate on the primed side of the scissile bond has a relatively lower effect on activity. The highest activity (k(cat)/K(M) = 2.8 +/- 0.6 (10(5) x m(-1)s(-1)) is observed for the pentamer 3-aminobenzoic acid-AIKAG-3-nitrotyrosine, which spans subsites S(3) to S(2)' on the enzyme. High pressure liquid chromatography and mass spectrometry analyses show that the substrates are cleaved at the site predicted from the autoprocessing experiments. These results show that SCP can display an important level of endopeptidase activity. Substitutions at position P(2) of the substrate clearly indicate that the S(2) subsite of SCP can readily accommodate substrates containing a hydrophobic residue at that position and that some topological preference exists for that subsite. Substitutions in positions P(3), P(1), and P(1)' had little or no effect on SCP activity. The substrate specificity outlined in this work further supports the similarity between SCP and the cysteine proteases of the papain family. From the data regarding the identified or proposed natural substrates for SCP, it appears that this substrate specificity profile may also apply to the processing of mammalian and streptococcal protein targets by SCP

Croyances et pratiques en évaluation des apprentissages étude des croyances et des pratiques des enseignants des cégeps à l'égard de l'évaluation des apprentissages /

Également disponible en version papierTitre de l'écran-titre (visionné le 13 janv. 2010)Bibliogr.: p. 263-27

Croyances et pratiques en évaluation des apprentissages étude des croyances et des pratiques des enseignants des cégeps à l'égard de l'évaluation des apprentissages /

Également disponible en version papierTitre de l'écran-titre (visionné le 13 janv. 2010)Bibliogr.: p. 263-27