Stress Effects on Working Memory, Explicit Memory, and Implicit Memory for Neutral and Emotional Stimuli in Healthy Men

Stress is a strong modulator of memory function. However, memory is not a unitary process and stress seems to exert different effects depending on the memory type under study. Here, we explored the impact of social stress on different aspects of human memory, including tests for explicit memory and working memory (for neutral materials), as well as implicit memory (perceptual priming, contextual priming and classical conditioning for emotional stimuli). A total of 35 young adult male students were randomly assigned to either the stress or the control group, with stress being induced by the Trier Social Stress Test (TSST). Salivary cortisol levels were assessed repeatedly throughout the experiment to validate stress effects. The results support previous evidence indicating complex effects of stress on different types of memory: A pronounced working memory deficit was associated with exposure to stress. No performance differences between groups of stressed and unstressed subjects were observed in verbal explicit memory (but note that learning and recall took place within 1 h and immediately following stress) or in implicit memory for neutral stimuli. Stress enhanced classical conditioning for negative but not positive stimuli. In addition, stress improved spatial explicit memory. These results reinforce the view that acute stress can be highly disruptive for working memory processing. They provide new evidence for the facilitating effects of stress on implicit memory for negative emotional materials. Our findings are discussed with respect to their potential relevance for psychiatric disorders, such as post traumatic stress disorder

La apomixis, su estudio y posibles usos

La apomixis es una forma de reproducción asexual a través de semillas que origina plantas genéticamente idénticas a la planta madre (clones). Su estudio para entender el funcionamiento, herencia y regulación a nivel génico de este fenómeno en pasto llorón puede traer grandes beneficios para la agricultura y la alimentación humana.Fil: Meier, Mauro Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Zappacosta, Diego Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Selva, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Cervigni, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Echenique, Carmen Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentin

Elaboración de material didáctico para el aprendizaje de la matemática: una visión neuropsicológica de los procesos de pensamiento involucrados en su aprendizaje

En este trabajo, proyecto factible especial de campo y descriptivo, se presenta el diseño de un material instruccional impreso de inecuaciones para la enseñanza de la matemática universitaria construido siguiendo los procesos de producción de medios instruccionales. La elaboración del material tomó en cuenta los nuevos hallazgos de la neurociencia y psicología del aprendizaje acerca de cómo el cerebro funciona cuando está aprendiendo matemática, entre ellos el sentido y significado que deben tener los contenidos matemáticos a ser aprendidos, la utilización de las expresiones verbales y simbólicas, los procesos de pensamiento: percepción completa y discriminada de los datos, asociación con información semejante guardada en su memoria, ordenamiento de los datos, clasificación, comparación y relación entre los mismos, reflexión sobre procedimientos utilizados, verificación de resultados y autoevaluación de lo aprendido y de lo no aprendido. El material elaborado ayudó significativamente a los estudiantes del curso a comprender y asimilar correctamente el tema, lo cual fue corroborado tanto por las notas que obtuvieron como por sus opiniones en la encuesta de evaluación. Basado en el impacto ocasionado en los estudiantes, la metodología utilizada en la elaboración de este material puede aplicarse en otros temas propios de la matemática

Trunk sway in mildly disabled multiple sclerosis patients with and without balance impairment

Multiple sclerosis (MS) causes a broad range of neurological symptoms. Most common is poor balance control. However, knowledge of deficient balance control in mildly affected MS patients who are complaining of balance impairment but have normal clinical balance tests (CBT) is limited. This knowledge might provide insights into the normal and pathophysiological mechanisms underlying stance and gait. We analysed differences in trunk sway between mildly disabled MS patients with and without subjective balance impairment (SBI), all with normal CBT. The sway was measured for a battery of stance and gait balance tests (static and dynamic posturography) and compared to that of age- and sex-matched healthy subjects. Eight of 21 patients (38%) with an Expanded Disability Status Scale of 1.0-3.0 complained of SBI during daily activities. For standing on both legs with eyes closed on a normal and on a foam surface, patients in the no SBI group showed significant differences in the range of trunk roll (lateral) sway angle and velocity, compared to normal persons. Patients in the SBI group had significantly greater lateral sway than the no SBI group, and sway was also greater than normal in the pitch (anterior-posterior) direction. Sway for one-legged stance on foam was also greater in the SBI group compared to the no SBI and normal groups. We found a specific laterally directed impairment of balance in all patients, consistent with a deficit in proprioceptive processing, which was greater in the SBI group than in the no SBI group. This finding most likely explains the subjective symptoms of imbalance in patients with MS with normal CBT

Marcadores moleculares para el estudio de la variabilidad dentro del complejo Eragrostis curvula

El pasto llorón es una especie forrajera que se destaca por su extraordinaria rusticidad, su capacidad para prosperar en suelos pobres en fertilidad y su aptitud para consolidar suelos erosionables. Se trata de un grupo botánico muy polimórfico. Los genotipos diploides son poco frecuentes y de reproducción sexual, mientras que los individuos tetraploides o de mayor ploidía se reproducen por apomixis. En el presente trabajo se utilizaron marcadores moleculares (RAPD, AFLP y EST-SSR) para analizar el modo reproductivo a través de pruebas de progenie, para determinar la homogeneidad intracultivar o pureza de semillas, para establecer relaciones genéticas entre genotipos dentro del complejo y para caracterizar nuevos materiales obtenidos por nuestro grupo. Ocho cultivares comerciales y tres nuevos materiales fueron estudiados. Patrones de amplificación uniformes y variables fueron obtenidos en progenies de plantas sexuales y apomícticas, respectivamente. La pureza de semillas fue evaluada sobre lotes de semillas comerciales, observándose contaminación en algunos lotes. Los AFLP fueron los marcadores con mayor potencial para la identificación de cultivares y los dendrogramas obtenidos usando SSR y AFLP fueron consistentes con estudios previos realizados con isoenzimas y caracteres morfológicos. El nuevo material vegetal tetraploide desarrollado por nuestro grupo de trabajo podría ser incluido dentro del tipo curvula. También se propone la creación de un nuevo tipo morfológico para el diploide, porque posee características morfológicas de tipo robusta y moleculares de tipo conferta.Weeping lovegrass is well adapted for forage production and useful for soil conservation in semiarid regions, constituting a morphologically diverse group. Diploid genotypes are unfrequent and reproduce sexually, whereas the tetraploids and plants of higher ploidy levels reproduce by apomixis. In the present work RAPD, AFLP and EST-SSR were used in order to assess the reproductive mode through progeny tests, to determine intracultivar homogeneity or seed purity, to establish genetic relationships among the cultivars within the complex and to characterize the new materials obtained by our group. Eight commercial cultivars and three new plant materials were analyzed. Uniform and variable patterns were observed in progenies of apomictic and sexual plants, respectively. Seed purity was evaluated in seed bulks, observing a certain degree of contamination with seeds from different sources. AFLP were the markers with the highest potential for cultivar identification. The clustering using SSR and AFLP was consistent with previous studies using isozymes and morphological traits. The new tetraploid materials developed by our own group should be included within the curvula type. We also proposed the creation of a new morphological type for the diploid, because it posses morphological characteristics of robusta and molecular profiles of the conferta type.Fil: Zappacosta, Diego Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Meier, Mauro Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Carrera, Alicia. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Pacheco, Gabriela. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación En Ciencias Veterinarias y Agronomicas. Instituto de Genetica; ArgentinaFil: Cardone, Susana. Universidad de Buenos Aires. Facultad de Agronomia; ArgentinaFil: Selva, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; ArgentinaFil: Echenique, Carmen Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiarida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiarida; Argentin

Genotype–phenotype correlations within the Geodermatophilaceae

The integration of genomic information into microbial systematics along with physiological and chemotaxonomic parameters provides for a reliable classification of prokaryotes. In silico analysis of chemotaxonomic traits is now being introduced to replace characteristics traditionally determined in the laboratory with the dual goal of both increasing the speed of the description of taxa and the accuracy and consistency of taxonomic reports. Genomics has already successfully been applied in the taxonomic rearrangement of Geodermatophilaceae (Actinomycetota) but in the light of new genomic data the taxonomy of the family needs to be revisited. In conjunction with the taxonomic characterisation of four strains phylogenetically located within the family, we conducted a phylogenetic analysis of the whole proteomes of the sequenced type strains and established genotype–phenotype correlations for traits related to chemotaxonomy, cell morphology and metabolism. Results indicated that the four isolates under study represent four novel species within the genus Blastococcus. Additionally, the genera Blastococcus, Geodermatophilus and Modestobacter were shown to be paraphyletic. Consequently, the new genera Trujillonella, Pleomorpha and Goekera were proposed within the Geodermatophilaceae and Blastococcus endophyticus was reclassified as Trujillonella endophytica comb. nov., Geodermatophilus daqingensis as Pleomorpha daqingensis comb. nov. and Modestobacter deserti as Goekera deserti comb. nov. Accordingly, we also proposed emended descriptions of Blastococcus aggregatus, Blastococcus jejuensis, Blastococcus saxobsidens and Blastococcus xanthilyniticus. In silico chemotaxonomic results were overall consistent with wet-lab results. Even though in silico discriminatory levels varied depending on the respective chemotaxonomic trait, this approach is promising for effectively replacing and/or complementing chemotaxonomic analyses at taxonomic ranks above the species level. Finally, interesting but previously overlooked insights regarding morphology and ecology were revealed by the presence of a repertoire of genes related to flagellum synthesis, chemotaxis, spore production and pilus assembly in all representatives of the family. A rich carbon metabolism including four different CO2 fixation pathways and a battery of enzymes able to degrade complex carbohydrates were also identified in Blastococcus genomes

Trajectories and Drivers of Genome Evolution in Surface-Associated Marine Phaeobacter

The extent of genome divergence and the evolutionary events leading to speciation of marine bacteria have mostly been studied for (locally) abundant, free-living groups. The genus Phaeobacter is found on different marine surfaces, seems to occupy geographically disjunct habitats, and is involved in different biotic interactions, and was therefore targeted in the present study. The analysis of the chromosomes of 32 closely related but geographically spread Phaeobacter strains revealed an exceptionally large, highly syntenic core genome. The flexible gene pool is constantly but slightly expanding across all Phaeobacter lineages. The horizontally transferred genes mostly originated from bacteria of the Roseobacter group and horizontal transfer most likely was mediated by gene transfer agents. No evidence for geographic isolation and habitat specificity of the different phylogenomic Phaeobacter clades was detected based on the sources of isolation. In contrast, the functional gene repertoire and physiological traits of different phylogenomic Phaeobacter clades were sufficiently distinct to suggest an adaptation to an associated lifestyle with algae, to additional nutrient sources, or toxic heavy metals. Our study reveals that the evolutionary trajectories of surface-associated marine bacteria can differ significantly from free-living marine bacteria or marine generalists

Increased apomixis expression concurrent with genetic and epigenetic variation in a newly synthesized Eragrostis curvula polyploid

Eragrostis curvula includes biotypes reproducing through obligate and facultative apomixis or, rarely, full sexuality. We previously generated a ‘‘tetraploid-dihaploid-tetraploid’’ series of plants consisting of a tetraploid apomictic plant (T), a sexual dihaploid plant (D) and a tetraploid artificial colchiploid (C). Initially, plant C was nearly 100% sexual. However, its capacity to form non-reduced embryo sacs dramatically increased over a four year period (2003–2007) to reach levels of 85–90%. Here, we confirmed high rates of apomixis in plant C, and used AFLPs and MSAPs to characterize the genetic and epigenetic variation observed in this plant in 2007 as compared to 2003. Of the polymorphic sequences, some had no coding potential whereas others were homologous to retrotransposons and/or protein-coding-like sequences. Our results suggest that in this particular plant system increased apomixis expression is concurrent with genetic and epigenetic modifications, possibly involving transposable elements.Fil: Zappacosta, Diego Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Ochogavía, Ana Claudia. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rodrigo, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Romero, José Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Meier, Mauro Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Garbus, Ingrid. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Pessino, Silvina Claudia. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Echenique, Carmen Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin