RESUMO
Aggressive behavior is thought to have evolved as a strategy for gaining access to resources such as territory, food, and potential mates. Across species, secondary sexual characteristics such as competitive aggression and territoriality are considered male-specific behaviors. However, although female-female aggression is often a behavior that is displayed almost exclusively to protect the offspring, multiple examples of female-female competitive aggression have been reported in both invertebrate and vertebrate species. Moreover, cases of intersexual aggression have been observed in a variety of species. Genetically tractable model systems such as mice, zebrafish, and fruit flies have proven extremely valuable for studying the underlying neuronal circuitry and the genetic architecture of aggressive behavior under laboratory conditions. However, most studies lack ethological or ecological perspectives and the behavioral patterns available are limited. The goal of this review is to discuss each of these forms of aggression, male intrasexual aggression, intersexual aggression and female intrasexual aggression in the context of the most common genetic animal models and discuss examples of these behaviors in other species.
RESUMO
Se analizan los componentes básicos para la adquisición de la lectura en castellano mediante la aplicación del modelo logístico lineal de Fisher (Linear Logistic Test Model [LLTM]). Participaron en el estudio 245 niños y niñas de edades comprendidas entre los 4 y los 9 años a los que se administró una extensa batería diseñada para evaluar distintos procesos básicos para la lectura (PROBALES). Se aplicaron técnicas de análisis factorial para seleccionar un subconjunto de ítems que mostrasen ajuste al modelo de Rasch. El LLTM permitió confirmar la validez del modelo teórico según el cual el aprendizaje de la lectura descansa en el desarrollo de tres habilidades básicas: reconocimiento de palabras, conciencia fonológica y comprensión de la lectura. Se muestra la capacidad predictiva del modelo mediante análisis discriminante, y se constata que se clasificó correctamente en su curso escolar al 68% de los participantes.
The basic components for the acquisition of reading in Spanish are analyzed by using the Fisher Linear Logistic Test Model (LLTM). An extensive battery designed to assess different Basic Processes for Reading (PROBALES, acronym in Spanish) was applied to 245 children aged 4 to 9. Factor analysis techniques were used to select a subset of items that would adjust to the Rasch model. The LLTM confirmed the validity of the theoretical model which states that reading acquisition relies on the development of three basic skills: word recognition, phonological awareness, and reading comprehension. The theoretical model's predictive ability is shown by discriminant analysis, thereby confirming that 68% of participants were correctly classified in their school grade.
RESUMO
Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenerative mechanisms. One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain. Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant. Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor. Thus, this mutant recapitulates two important features of human neurodegenerative diseases, i.e., vulnerability of certain neuronal populations and progressive degeneration, offering a unique scenario in which to unravel the specific mechanisms in an easily tractable organism.
Assuntos
Drosophila/genética , Expressão Gênica , Doenças Neurodegenerativas/genética , Envelhecimento/patologia , Animais , Apoptose , Proteínas de Ligação a DNA/genética , Proteínas de Drosophila/genética , Atividade MotoraRESUMO
Clock output pathways are central to convey timing information from the circadian clock to a diversity of physiological systems, ranging from cell-autonomous processes to behavior. While the molecular mechanisms that generate and sustain rhythmicity at the cellular level are well understood, it is unclear how this information is further structured to control specific behavioral outputs. Rhythmic release of pigment dispersing factor (PDF) has been proposed to propagate the time of day information from core pacemaker cells to downstream targets underlying rhythmic locomotor activity. Indeed, such circadian changes in PDF intensity represent the only known mechanism through which the PDF circuit could communicate with its output. Here we describe a novel circadian phenomenon involving extensive remodeling in the axonal terminals of the PDF circuit, which display higher complexity during the day and significantly lower complexity at nighttime, both under daily cycles and constant conditions. In support to its circadian nature, cycling is lost in bona fide clockless mutants. We propose this clock-controlled structural plasticity as a candidate mechanism contributing to the transmission of the information downstream of pacemaker cells.
Assuntos
Comportamento Animal/fisiologia , Ritmo Circadiano/fisiologia , Drosophila melanogaster/fisiologia , Vias Neurais/fisiologia , Neurônios/citologia , Neurônios/fisiologia , Animais , Relógios Biológicos , Encéfalo/citologia , Encéfalo/fisiologia , Proteínas CLOCK , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Neuropeptídeos/metabolismo , Transativadores/genéticaRESUMO
Great efforts have been directed to the dissection of the cell-autonomous circadian oscillator in Drosophila. However, less information is available regarding how this oscillator controls rhythmic rest-activity cycles. We have identified a viable allele of roundabout, robo(hy), where the period of locomotor activity is shortened. From its role in axon-pathfinding, we anticipated developmental defects in clock-relevant structures. However, robo(hy) produced minor defects in the architecture of the circuits essential for rhythmic behaviour. ROBO's presence within the circadian circuit strengthened the possibility of a novel role for ROBO at this postdevelopmental stage. Genetic interactions between pdf (01) and robo(hy) suggest that ROBO could alter the communication within different clusters of the circadian network, thus impinging on two basic properties, periodicity and/or rhythmicity. Early translocation of PERIOD to the nucleus in robo(hy) pacemaker cells indicated that shortened activity rhythms were derived from alterations in the molecular oscillator. Herein we present a mutation affecting clock function associated with a molecule involved in circuit assembly and maintenance.