A study of chymotrypsin immobilization conditions for improved peptide mapping

La cartographie peptidique est une technique de grande importance utilisée lors de l’identification des protéines et la caractérisation des modifications post-traductionnelles des protéines. Deux méthodes sont utilisées afin de couper les protéines en peptides pour la cartographie : les méthodes chimiques et les méthodes enzymatiques. Dans ce projet, l’enzyme chymotrypsine a été utilisée pour l’hydrolyse (la digestion) des liens peptidiques. Cependant, l’autoprotéolyse des enzymes peut augmenter la complexité des échantillons, rendant ainsi ardue l’obtention de pics résolus suite à l’apparition de pics non-désirés dans la carte peptidique. Par conséquent, nous avons utilisé la réticulation des enzymes protéolytiques par réaction avec le glutaraldéhyde (GA) donnant une enzyme insoluble afin de réduire l’autoprotéolyse. L’immobilisation de la chymotrypsine par GA a été effectuée selon une méthode rapportée précédemment par le groupe Waldron. L’électrophorèse capillaire (CE) couplée à l’absorption UV-visible a été utilisée pour la séparation et la détection de peptides et pour obtenir ainsi une cartographie peptidique. Deux tampons différents ont été évalués afin d’obtenir les meilleures conditions pour la digestion de substrats protéiques par la chymotrypsine libre (soluble) ou la GAchymotrypsine et l’analyse par CE. Les cartes des peptides autoprotéolytiques ont été comparées entre les deux formats de chymotrypsine. Afin d’améliorer la cartographie peptidique, nous avons évalué trois méthodes de conditionnement du capillaire CE et deux méthodes pour stopper la digestion. Le bicarbonate d’ammonium s’est avéré être le tampon optimal pour la digestion en solution et l’utilisation d’un bain d’acétone et de glace sèche s’est avérée être la méthode optimale pour stopper la digestion. Une solution de SDS, 25 mM, dans l’étape de rinçage a été utilisée après chaque analyse CE et a permis d’améliorer la résolution des cartes peptidiques. La comparaison entre l’autoprotéolyse de la chymotrypsine libre et de celle immobilisé par GA a été effectuée par des tests utilisant une gamme de six différentes combinaisons de conditions afin d’évaluer le temps (30 et 240 min) et la température de digestion (4, 24 et 37°C). Dans ces conditions, nos résultats ont confirmé que le GA-chymotrypsine réduit l’autoprotéolyse par rapport à l’enzyme libre. La digestion (à 37°C/240 min) de deux substrats modèles par la chymotrypsine libre et immobilisée en fonction de la température de dénaturation du substrat a été étudiée. iii Avant la digestion, les substrats (l’albumine de sérum bovine, BSA, et la myoglobine) ont été dénaturés par chauffage pendant 45 min à trois températures différentes (60, 75 et 90°C). Les résultats ont démontré que la dénaturation par chauffage du BSA et de la myoglobine n’a pas amélioré la cartographie peptidique pour la GA-chymotrypsine, tandis que la digestion de ceux-ci en présence de la chymotrypsine libre a amélioré de façon quantifiable à des températures élevées. Ainsi, le chauffage du substrat à 90°C avec l’enzyme soluble facilite le dépliement partiel du substrat et sa digestion limitée, ce qui a été mieux pour la myoglobine que pour la BSA.

Amenaza Interdependiente en la Región de los Grandes Lagos

El objetivo de esta monografía es analizar los alcances de la presencia de grupos armados ilegales como elementos determinantes en el origen de un subcomplejo de seguridad regional entre la República Democrática del Congo, Ruanda y Burundi. Se busca explicar cómo un conflicto étnico se traduce en la presencia de grupos insurgentes, y a su vez, establece una amenaza interdependiente entre los líderes políticos de dichos países, que permite hablar del subcomplejo de seguridad. Para lograr lo anterior, son pertinentes los postulados teóricos de los Complejos de Seguridad Regional de Barry Buzan, ya que identifican la manera como se estructuran, localizan, y evolucionan estas unidades de análisis. Finalmente, este análisis se complementa con el método de estudio propuesto por Jeremy M. Weinstein para comprender por qué y para qué se crean grupos insurgentes.

Teachers reactions to outcomes-based music education in South African primary schools

This article examines the reactions of specialist music teachers to the introduction of Outcomes-Based Education (OBE) in South Africa. OBE has been seen in post-apartheid South Africa as a way to transform education and address the imbalances of the past. The study reported here used questionnaires to explore attitudes of teachers at independent schools in Johannesburg in the first year of implementing OBE. Analysis of data revealed both positive and negative attitudes as well as the strong need for teachers professional development if OBE is to succeed.

Travelling drum with different beats: experiencing African music and culture in Australian teacher education

This article reports on a study that examined the effectiveness of introducing African music and culture to Australian non-specialist primary teacher education students at Deakin University in Melbourne (Australia). The study demonstrates that African music enhanced the generic musical experiences, learning, motivation, interest, confidence and competence of students in their fourth year of teacher education. The research also addressed the significance and contribution of African music and culture as a cross-cultural experience for these beginning teachers who in turn could provide similar experiences for their own students. This study highlighted the author's role and cultural identity as a South African music educator in transmitting the music and culture represented in 'the travelling drum' to a cohort of students with a predominantly Eurocentric orientation. By extension, this curriculum initiative broadened students' understanding and application of indigenous methods of teaching and learning as part of a global experience. Such a curriculum represents a pathway to many other forms of non-Western indigenous knowledge of music, culture and pedagogy that can be mapped out as a journey along a multicultural route towards 'internationalising the curriculum'.

A new voice in a new place: musical encounters with a difference

Australian education providers at the university level are being challenged to be more inclusive of cultural diversity and associated knowledge systems in their curricula. This article reports on some findings of a research study that aimed to evaluate the introduction of African music to primary teacher education students and to provide them with a context for assimilating African music into their own teaching practice. This paper reports on my work as a music educator in sharing my different worlds of experience ‘with one voice’ in order to expand students’ local knowledge base. It also discusses the nature and applications of African music and demonstrates some aspects that correlate with Western music. Through a study of both Western and African pedagogies and repertoire, students were able to gain a more holistic perspective of the role of music in society and were able to contextualize and transfer epistemological and pedagogical insights from one society to another.

Teacher attitudes and perceptions of primary school music education at independent schools in South Africa

As South Africa enters the new millennium and is currently in its second term of democracy, the question remains: is outcomes-based education preliminary the way forward for learners in South Africa. The new education system recognises the importance of arts education and specifically music education at the primary school level. This article focuses on music education at independent schools in Gauteng, South Africa. The reporting of this article is based on the author's doctoral thesis entitled "Outcomes-based music education in the foundation phase at independent schools in Gauteng, South Africa". The principal form of research was a questionnaire sent to music teachers at primary schools registered with the Independent Schools Council (ISC). The purpose of the questionnaires was to contribute to a study on teachers' perceptions, attitudes and opinions regarding music education and outcomes-based education. The questionnaire was divided into three main sections, namely: personal and professional details, outcomes-based education and general information. Both open and closed types of questions were employed. The questionnaire yielded both ambivalent views about the change of the education system as well as the inclusion of music as an area of learning within "Arts and Culture". It also identified current teaching trends and exposed areas of weakness that call for attention.

Cross cultural engagement: teaching African music to Australian students

This paper reports on research that examined the effectiveness of introducing rhythmic concepts through an unfamiliar musical genre to Australian generalist prim my teacher education students. The genre selected was African music, in particular action songs, dance and instrumental improvisation. The methodologies of Orff, Kodaly and Dalcroze were taught through the repertoire of African music in order to foster a closer relationship between pedagogical theory and practice and to teach rhythm through cross-cultural engagement. Through analyses of questionnaire and interview data, it was demonstrated that African music had a positive effect on students' conjidence as non-specialists music teachers and enhanced their skills in staff, sol-fa, hand notation and performance. Also students were not only highly motivated to engage with this new musical genre, but also gained an increased understanding of African culture. It is argued that African music was perceived by students not so much as a "novelty", but as a source of genuine motivation, interest and enjoyment. Its potential for extending student understanding of rhythm as well as taking a significant step towards internationalizing the curriculum for a cohort of predominantly Anglo-Celtic, pre-service teachers is also explored.

Smaller steps into longer journeys : experiencing African music and expressing culture

This paper outlines an exploratory research project that draws on survey data from both primary and secondary school music teachers in Victoria. The research stems from a study that I undertook in 2002-2003 with final year Deakin University undergraduate students. That project investigated the potential of African music to enhance the generic musical experiences, learning, motivation, interest, confidence and competence of non-specialist primary teacher education students. The research project being reported in this paper is an extension of the previous study to focus on practising music teachers at both primary and secondary school levels. The research addresses the significance and contribution of African music and culture as a cross-cultural experience for music teachers, their students and the wider community. It further considers my role as an African music practitioner in terms of transformation and acculturation. This paper outlines the progress of, and provides preliminary data about, the emergence of an innovative area of teaching and learning based on African music in Victorian schools. It also explores the notion of why cross-cultural and multi-cultural engagement matters in the contemporary context of educational change.