RESUMEN
Internationalization has commanded an ever-more prominent position in higher education over recent years, and is now firmly entrenched. While academia has long been outward looking-international research collaborations, conferences and student exchanges are well-established practices-it is relatively recently that internationalization has become a goal in its own right, rather than a consequence of normal academic activity. There are multiple interdependent drivers behind this: a focus on graduate employability and development of broad competencies and transferable skills in addition to subject-specific training, 'international awareness' being confirmed as a graduate attribute that is highly valued by employers, the availability of detailed information enabling prospective students to choose between Higher Education Institutions on the basis of their international opportunities and graduate employment rates, increasing competition between Institutions to attract the best students and to ascend national and international league tables, and (both driving and reflecting these trends) national policy frameworks. This minireview focuses on two aspects of internationalization of direct relevance to microbiology students and academic staff in a typical Higher Education Institution: student research placements overseas, and the impact of international mobility on teaching practice and the student experience. Practical strategies for developing intercultural awareness and enhancing employability are highlighted.
Asunto(s)
Educación de Postgrado , Empleo , Internacionalidad , Humanos , Estudios Prospectivos , EstudiantesRESUMEN
Wnt signaling pathways have essential roles in developing embryos and adult tissue, and alterations in their function are implicated in many disease processes including cancers. The major nuclear transducers of Wnt signals are the Tcf/LEF family of transcription factors, which have binding sites for both the transcriptional co-repressor groucho, and the co-activator beta-catenin. The early Xenopus embryo expresses three maternally inherited Tcf/LEF mRNAs, and their relative roles in regulating the expression of Wnt target genes are not understood. We have addressed this by using antisense oligonucleotides to deplete maternal XTcf1 and XTcf4 mRNAs in oocytes. We find that XTcf1 represses expression of Wnt target genes ventrally and laterally, and activates their expression dorsally. Double depletions of XTcf1 and XTcf3 suggest that they act cooperatively to repress Wnt target genes ventrally. In contrast, XTcf4 has no repressive role but is required to activate expression of Xnr3 and chordin in organizer cells at the gastrula stage. This work provides evidence for distinct roles for XTcfs in regulating Wnt target gene expression.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica , Factor Nuclear 1-alfa del Hepatocito/metabolismo , Factor 1 de Transcripción de Linfocitos T/metabolismo , Factores de Transcripción TCF/metabolismo , Proteínas Wnt/metabolismo , Proteínas de Xenopus/metabolismo , Animales , Embrión no Mamífero/metabolismo , Glicoproteínas/genética , Glicoproteínas/metabolismo , Hibridación in Situ , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , ARN Mensajero/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Factor 1 de Transcripción de Linfocitos T/genética , Factores de Transcripción TCF/genética , Proteína 1 Similar al Factor de Transcripción 7 , Proteína 2 Similar al Factor de Transcripción 7 , Factor de Crecimiento Transformador beta/genética , Factor de Crecimiento Transformador beta/metabolismo , Proteínas Wnt/genética , Xenopus/embriología , Xenopus/metabolismo , Proteínas de Xenopus/genéticaRESUMEN
The Wingless (Wg)/Wnt signal transduction pathway regulates many developmental processes through a complex of Armadillo(Arm)/beta-catenin and the HMG-box transcription factors of the Tcf family. We report the identification of a new component, Pygopus (Pygo), that plays an essential role in the Wg/Wnt signal transduction pathway. We show that Wg signaling is diminished during embryogenesis and imaginal disc development in the absence of pygo activity. Pygo acts downstream or in parallel with Arm to regulate the nuclear function of Arm protein. pygo encodes a novel and evolutionarily conserved nuclear protein bearing a PHD finger that is essential for its activity. We further show that Pygo can form a complex with Arm in vivo and possesses a transcription activation domain(s). Finally, we have isolated a Xenopus homolog of pygo (Xpygo). Depletion of maternal Xpygo by antisense deoxyoligonucleotides leads to ventralized embryonic defects and a reduction of the expression of Wnt target genes. Together, these findings demonstrate that Pygo is an essential component in the Wg/Wnt signal transduction pathway and is likely to act as a transcription co-activator required for the nuclear function of Arm/beta-catenin.
Asunto(s)
Proteínas Portadoras/fisiología , Proteínas de Drosophila/fisiología , Péptidos y Proteínas de Señalización Intracelular , Proteínas Proto-Oncogénicas/metabolismo , Transducción de Señal , Transactivadores , Proteínas de Pez Cebra , Secuencia de Aminoácidos , Animales , Proteínas del Dominio Armadillo , Proteínas Portadoras/genética , Núcleo Celular/metabolismo , Drosophila , Proteínas de Drosophila/genética , Proteínas de Insectos/metabolismo , Larva/metabolismo , Datos de Secuencia Molecular , Oocitos/metabolismo , Estructura Terciaria de Proteína , Factores de Transcripción , Activación Transcripcional , Proteínas Wnt , Proteína Wnt1 , XenopusRESUMEN
The community effect is an interaction among a group of many nearby cells that is necessary for them to maintain tissue-specific gene expression and differentiate co-ordinately. A community interaction is required for the muscle precursor cells of the Xenopus embryo to develop into terminally differentiated muscle, but exactly when and where the community effect acts during myogenesis has not been determined. Here, we ask whether dependence on the community effect varies with the developmental age of the muscle precursor cells. We find that dependence on the community signal changes with time through the muscle precursor cell population. During neurulation muscle precursor cells that are still in the vicinity of the blastopore and that are fated to form posterior muscle continue to require interactions with their neighbours, while differentiation of the anterior paraxial mesoderm,which gastrulated earlier, is independent of cell contact at this time. Thus the time during which a particular sub-population of muscle precursor cells requires a community interaction is related to their final destination along the anterior-posterior axis. In addition we show that this later acting community interaction around the blastopore involves FGF signalling.
Asunto(s)
Desarrollo de Músculos/fisiología , Músculo Esquelético/embriología , Xenopus/embriología , Animales , Tipificación del Cuerpo , Comunicación Celular , Diferenciación Celular , Comunicación , Embrión no Mamífero/fisiología , Mesodermo/fisiología , MorfogénesisRESUMEN
The animal cap cells of Xenopus blastulae behave as multi-potent stem cells in so far as they can differentiate along many unrelated pathways according to the kind and amount of signal factor that they experience. At first, animal cap cells activate early zygotic genes across a broad range of TGFbeta concentrations; soon after this, they activate later genes more intensely and over a narrow concentration range. Here we show that uncommitted blastula cells can be directed, by the sequential influence of a particular concentration of a TGFbeta morphogen and an FGF-mediated community effect, to form a homogeneous single cell type. As a result of these two signalling processes, an entire population of animal cap cells can be converted, in the absence of other signals, to a uniform population of one tissue type. Mesoderm cells that experience a particular concentration of activin increase their XMyoD expression by 10-fold and become distinct from neighbouring cells that received lower or higher concentrations of activin. The signalling processes that we employ here may be important in normal development and useful in guiding stem cell differentiation.