Identification and functional characterization of the putative members of the CTDK-1 kinase complex as regulators of growth and development in Aspergillus nidulans and Aspergillus fumigatus.

Asexual spores are the main vehicle used by fungi to disperse to new niches. The Eurotiomycete Aspergillus nidulans is the main reference for the study of the genetic/molecular control of asexual development. In this species, Flb proteins control the expression of the master gene brlA, and thus, loss-of-function mutations in flb (upstream developmental activation [UDA]) genes block brlA transcription and, consequently, the production of conidiophores, the structures bearing asexual spores known as conidia. However, the aconidial phenotype of specific flb mutants, such as that of the ΔflbB strain, is reverted under salt-stress conditions. Previously, we generated a collection of second-site mutants of ΔflbB unable to conidiate on culture medium supplemented with NaH2PO4 (0.65 M). Here, we identified a Gly347Stop mutation within flpA as responsible for the FLIP57 phenotype and characterized the role of the putative cyclin FlpA and the remaining putative components of the C-terminal domain kinase-1 (CTDK-1) complex in A. nidulans and Aspergillus fumigatus. FlpA, Stk47, and FlpB are necessary (i) for timely germination, (ii) in the transition from metulae to phialides (the cells generating conidia) during conidiophore development, and (iii) for the development of sexual structures (cleistothecia) in A. nidulans. The three proteins are nuclear, and the nucleoplasmic localization of Stk47 depends on the activity of FlpA, which correlates with the retention of Stk47 by FlpA in pull-down assays. Overall, this work links the putative CTDK-1 complex of aspergilli with growth and developmental control. Identification of a mutation in flpA as inhibitor of conidiation in A. nidulans and functional characterization of FlpA, Stk47 and FlpB as putative members of the C-terminal domain kinase complex CTDK-1 in A. nidulans and A. fumigatus.IMPORTANCEAspergillus fumigatus has been included by the World Health Organization in the priority list of fungal pathogens because (i) it causes 90% of invasive aspergillosis cases, with a high mortality rate, and (ii) infections are becoming increasingly resistant to azole antifungals. A. nidulans is an opportunistic pathogen and a saprotroph which has served during the last 80 years as a reference system for filamentous fungi. Here, we characterized the role in morphogenesis and development of the putative transcriptional cyclin/kinase complex CTDK-1 in both aspergilli. The null mutants of the corresponding genes showed delayed germination, aberrant conidiophore development, and inhibition of cleistothecia production. While in higher eukaryotes this complex is formed only by a cyclin and a kinase, the fungal complex would incorporate a fungal-specific third component, FlpB, which would enable the interaction between the kinase (Stk47) and the cyclin (FlpA) and may be used as a target for antifungals.

Prior stress promotes the generalization of contextual fear memories: Involvement of the gabaergic signaling within the basolateral amygdala complex.

Fear generalization occurs when a response, previously acquired with a threatening stimulus, is transferred to a similar one. However, it could be maladaptive when stimuli that do not represent a real threat are appraised as dangerous, which is a hallmark of several anxiety disorders. Stress exposure is a major risk factor for the occurrence of anxiety disorders and it is well established that it influences different phases of fear memory; nevertheless, its impact on the generalization of contextual fear memories has been less studied. In the present work, we have characterized the impact of acute restraint stress prior to contextual fear conditioning on the generalization of this fear memory, and the role of the GABAergic signaling within the basolateral amygdala complex (BLA) on the stress modulatory effects. We have found that a single stress exposure promoted the generalization of this memory trace to a different context that was well discriminated in unstressed conditioned animals. Moreover, this effect was dependent on the formation of a contextual associative memory and on the testing order (i.e., conditioning context first vs generalization context first). Furthermore, we observed that increasing GABA-A signaling by intra-BLA midazolam administration prior to the stressful session exposure prevented the generalization of fear memory, whereas intra-BLA administration of the GABA-A antagonist (Bicuculline), prior to fear conditioning, induced the generalization of fear memory in unstressed rats. We concluded that stress exposure, prior to contextual fear conditioning, promotes the generalization of fear memory and that the GABAergic transmission within the BLA has a critical role in this phenomenon.

Las atribuciones de incontrolabilidad en el origen de las expectativas de desesperanza en adolescentes / Uncontrollability in the origin of hopelessness expectancies in adolescents

La percepción de no contingencia se muestra determinante en el surgimiento de las expectativas de incontrolabilidad desde el modelo original de Indefensión Aprendida. En su última versión, las expectativas de desesperanza, que consisten en percibir el futuro como incontrolable, dependen de la atribución de los acontecimientos negativos a causas globales y estables. En este estudio se examina si las atribuciones de incontrolabilidad son a su vez determinantes de las expectativas de desesperanza. En una muestra de 256 estudiantes (15-20 años), se administraron el Cuestionario de Estilos Cognitivos para Adolescentes Españoles, el Listado de Experiencias Vitales y la Escala de Desesperanza. Se encontró que ni la globalidad ni la estabilidad predecían expectativas de desesperanza, si bien atribuir los acontecimientos negativos a causas incontrolables las incrementaba significativamente. Estos hallazgos muestran la utilidad de incorporar una nueva dimensión atribucional, que evalúa la percepción de no contingencia, en la predicción de las expectativas de desesperanza (AU)

In the Learned Helplessness model, perception of non contingency is a key factor in the appearance of uncontrollability expectations. In its last version, this model poses that hopelessness expectancies, which consist in perceiving the future as uncontrollable, depend on attributing negative events to stable and global causes. In this study we tested if attributions of uncontrollability are also needed for the development of hopelessness. We used the Spanish Cognitive Style Questionnaire for Adolescents, the Life Experiences Survey, and the Hopelessness Scale in a sample of 256 students (aged 15-20 yrs). Results showed that neither globality, nor stability, predicted hopelessness expectations; however, attributing negative events to uncontrollable causes did predict hopelessness. These findings show the utility of including a new attributional dimension that evaluates the perception of non contingency in the prediction of hopelessness expectancies (AU)