Saccharification Kinetics at Optimised Conditions of Tapioca by Glucoamylase Immobilised on Mesostructured Cellular Foam Silica

As insoluble substrates such as tapioca can be used to make chemical compounds, saccharification of tapioca by glucoamylase immobilised on mesostructured cellular foam (MCF) silica using Box-Behnken Design of experiment was conducted to optimize this process so that the experimental results can be used to develop large-scale operations. The experiments gave dextrose equivalent (DE) values of 6.15–69.50% (w/w). Factors of pH and temperature affected the process highly. The suggested quadratic polynomial model is significant and considered acceptable (R2 = 99.78%). Justification of the model confirms its validity and adequacy where the predicted DE shows a good agreement with the experimental results. The kinetic constants (Vmax, KM) produced by the immobilised enzyme differed highly from the values yielded by free glucoamylase indicating reduction of substrate access to enzyme active sites had occurred.

Dengue vaccine: an update on recombinant subunit strategies

Dengue is an increasing public health problem worldwide, with the four serotypes of the virus infecting over 390 million people annually. There is no specific treatment or antiviral drug for dengue, and prevention is largely limited to controlling the mosquito vectors or disrupting the human-vector contact. Despite the considerable progress made in recent years, an effective vaccine against the virus is not yet available. The development of a dengue vaccine has been hampered by many unique challenges, including the need to ensure the absence of vaccine-induced enhanced severity of disease. Recombinant protein subunit vaccines offer a safer alternative to other vaccine approaches. Several subunit vaccine candidates are presently under development, based on different structural and non-structural proteins of the virus. Novel adjuvants or immunopotentiating strategies are also being tested to improve their immunogenicity. This review summarizes the current status and development trends of subunit dengue vaccines.

A CFSE-based assay of proliferative response of lymphocytes to stimulation with dengue viruses

Dengue viruses (DENVs) are human pathogens that constitute a significant threat worldwide. Since they up-regulate MHC class I molecules; the cell-mediated immunity may play an important role in the defense against viruses. In this work, we tested a CFSE-based assay in determining proliferative response of lymphocytes isolated from mice or monkeys previously immunized with various DENV antigens to in vitro stimulation with DENVs. A positive proliferative response was obtained with lymphocytes of animals immunized with either live DENV-2 or its recombinant proteins. A similar result was also obtained with CD8+ T cells from mice immunized with live DENV-1 or DENV-2 following stimulation with homologous viruses. A comparison of the carboxyfluorescein diacetate succinimidyl ester (CFSE)-based and a 3H-thymidine incorporation-based assays of proliferative response of total lymphocytes showed a fair correlation of results of both assays. However, the CSFE-based assay offers in addition the determination of contribution of the CD8+ or other subsets of T cells to total proliferative response. These results represent the first and successful application of a CFSE-based assay to the evaluation of cell-mediated immunity to DENVs. This assay might be also exploited in testing candidate DENV vaccines.

Database model and specification of GermOnline Release 2.0, a cross-species community annotation knowledgebase on germ cell differentiation

GermOnline is a web-accessible relational database that enables life scientists to make a significant and sustained contribution to the annotation of genes relevant for the fields of mitosis, meiosis, germ line development and gametogenesis across species. This novel approach to genome annotation includes a platform for knowledge submission and curation as well as microarray data storage and visualization hosted by a global network of servers.

AVAILABILITY

The database is accessible at http://www.germonline.org/. For convenient world-wide access we have set up a network of servers in Europe (http://germonline.unibas.ch/; http://germonline.igh.cnrs.fr/), Japan (http://germonline.biochem.s.u-tokyo.ac.jp/) and USA (http://germonline.yeastgenome.org/).

SUPPLEMENTARY INFORMATION

Extended documentation of the database is available through the link 'About GermOnline' at the websites.

GermOnline, a cross-species community knowledgebase on germ cell differentiation

GermOnline provides information and microarray expression data for genes involved in mitosis and meiosis, gamete formation and germ line development across species. The database has been developed, and is being curated and updated, by life scientists in cooperation with bioinformaticists. Information is contributed through an online form using free text, images and the controlled vocabulary developed by the GeneOntology Consortium. Authors provide up to three references in support of their contribution. The database is governed by an international board of scientists to ensure a standardized data format and the highest quality of GermOnline's information content. Release 2.0 provides exclusive access to microarray expression data from Saccharomyces cerevisiae and Rattus norvegicus, as well as curated information on approximately 700 genes from various organisms. The locus report pages include links to external databases that contain relevant annotation, microarray expression and proteome data. Conversely, the Saccharomyces Genome Database (SGD), S.cerevisiae GeneDB and Swiss-Prot link to the budding yeast section of GermOnline from their respective locus pages. GermOnline, a fully operational prototype subject-oriented knowledgebase designed for community annotation and array data visualization, is accessible at http://www.germonline.org. The target audience includes researchers who work on mitotic cell division, meiosis, gametogenesis, germ line development, human reproductive health and comparative genomics.

A recombinant envelope protein from Dengue virus purified by IMAC is bioequivalent with its immune-affinity chromatography purified counterpart

Semi-purified DEN-4 envelope protein, obtained in Pichia pastoris, was capable of generating neutralising and protecting antibodies after immunisation in mice. Here we compared two purification processes of this recombinant protein using two chromatographic steps: immune-affinity chromatography and immobilised metal ion adsorption chromatography (IMAC). The protein purified by both methods produced functional antibodies reflected by titres of haemagglutination inhibition and neutralisation. IMAC could be used as an alternative for high scale purification.