The influence of protein kinase A activity on transport of newly synthesized vesicular stomatitis virus G glycoprotein along the exocytic pathway was examined. Transport of vesicular stomatitis virus G glycoprotein to the cell surface was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89), a selective inhibitor of protein kinase A. This block occurred at the exit of the Golgi complex, whereas transport through the Golgi compartments or from the endoplasmic reticulum to the Golgi was decreased in the presence of H-89. As judged by immunofluorescence endoplasmic reticulum to Golgi transport was accelerated in cells incubated with activators of protein kinase A such as isobutylmethylxanthine (IBMX) or forskolin (FK). Treatment with IBMX and FK also increased transport from the trans-Golgi network to the cell surface. During incubation with IBMX and FK, the organization of the Golgi complex was altered showing intercisternae fusion and miscompartmentalization of resident proteins. These structural changes affected both the kinetics of acquisition of endoglycosidase H resistance and transport activities. These data support a differential regulatory role for protein kinase A in different transport steps along the exocytic pathway. In particular, transport from the trans-Golgi network to the cell surface was dependent on protein kinase A activity. In addition, the results suggest the involvement of this enzyme on the maintenance of the Golgi complex organization.

Working smart: the use of 'cognitive enhancers' by UK University students Cognitive enhancers include a wide range of substances including prescription medication for attentional deficient disorders and pharmacological substances for cognitive augmentation. Students have recently been identified as the largest cohort of users. Most research on student use of cognitive enhancers has been undertaken in the United States. This study utilised a mixed methods sequential explanatory approach to investigate cognitive enhancer use among UK university students specifically to aid study. A bespoke online survey was distributed throughout the UK. The findings informed the development of a qualitativeinterview study comprising fifteen participants. In total, 506 responses to the online survey were received from 54 UK institutions. 46% of respondents reported using recreational drugs and 19% reported having used cognitive enhancers. Males were two and a half times more likely to use cognitive enhancers than females. Participants reported various motives for using cognitive enhancers, the most frequent being to meet the demands of coursework, to improve focus or maintain wakefulness. The qualitative findings revealed that cognitive enhancers are widely accessible and are used to enhance performance in terms of motivation, concentration and meeting academic deadlines. The findings of this study will be of interest to a wide range of services within Universities across the UK.

The present work aims to develop a growth medium to render a wild-type strain of Saccharomyces cerevisiae permeable to the antifungal drug Brefeldin A. In the current study, a synthetic medium containing 0.1% L-proline and supplemented with 3.0 × 10 −3 % SDS is employed. When Brefeldin A is added to this medium, a wild-type strain shows increased growth sensitivity and a diminished transport of the amino acid L-leucine. Since Brefeldin A exerts its effect on the endoplasmic reticulum and the Golgi apparatus, the medium permits the study of the drug effect on the intracellular traffic of L-leucine permeases. INTRODUCTIONBefore their delivery to the plasma membrane (PM), the different permeases involved in amino acid transport, like most of the membrane proteins, enter the membrane of the endoplasmic reticulum (ER). They then proceed through the protein secretory pathway of the ER, via the Golgi complex (GC) and exocytic vesicles, until they finally reach the PM [1].A very useful agent for investigating permease transport through the secretory pathway is the antifungal agent, Brefeldin A (BFA), which reversibly blocks the transport of proteins from the ER to the Golgi [2,3,4]. This drug can be used to create a temporary block in transport, allowing accumulation of permeases in the ER and depletion of these permeases downstream. In addition, when the BFA block is present, loss of permease molecules from the PM through endocytosis can be studied independent of their replacement via the secretory pathway. Moreover, release of the BFA block would permit the investigation of the dynamics of replacing the permeases in the depleted membrane. Because wild-type yeast has a very low apparent permeability to BFA, previous investigations have used strains bearing the erg6 mutation that blocks the final methylation reaction in ergosterol biosynthesis. The lack of ergosterol in the PM changes the permeability properties of the membrane and renders cells sensitive to several inhibitors, including BFA and the dye, crystal violet (CV) [2]. These changes appear to be at least partly due to decreases in activity of multidrug resistance pumps such as Pdr5p [5].There are several disadvantages of using the erg6 mutation to obtain BFA sensitivity. The mutation itself causes a marked increase in permeability to sodium and lithium ions [6]. Efficiency of genetic transformation is lowered dramatically, and sexual conjugation is also greatly reduced. Moreover, transport of tryptophan is lowered substantially [7].We have developed a simple method for obtaining BFA sensitivity without requiring the introduction of erg6. Because the method requires no genetic manipulation, it can be applied to wild-type cells and to strains already bearing various mutations related to secretion, to altered amino acid transport, and to modified permease turnover. The method depends upon the use of an SDS-supplemented synthetic growth medium in which the wild-type strain MMY2 presents increased sensitivity to BFA. At appropriate concentrations, BFA inhibits grow...

Presentamos una propuesta metodológica cualitativa para indagar aprendizajes de una población de estudiantes. Utilizamos el concepto de red semántica para la representación gráfica de las respuestas individuales de los estudiantes frente a un problema determinado. Asimismo, el modelo de procesamiento de la información proporcionó la base teórico-práctica para la confección de los caminos cognitivos asociativos expresados por cada sujeto. Esta combinación teórico metodológica permitió elaborar redes semánticas poblacionales que representan la información acerca de los conocimientos declarativos de la población. Se propuso a estudiantes universitarios, de las asignaturas Biología y Química Biológica de distintas carreras, un problema de múltiples resoluciones acerca del metabolismo de los carbohidratos. Al ordenar las respuestas de todos los estudiantes en redes semánticas detectamos: (a) tendencias generales de errores arraigados que se repiten en cada asignatura, y (b) tendencias específicas de estrategias de respuestas o de errores que sólo aparecen en alguna de las poblaciones.

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