Transmembrane semaphorins (Semas) serve evolutionarily conserved guidance roles, and some function as both ligands and receptors. However, the molecular mechanisms underlying the transduction of these signals to the cytoskeleton remain largely unknown. We have identified two direct regulators of Rho family small GTPases, pebble (a Rho guanine nucleotide exchange factor [GEF]) and RhoGAPp190 (a ...

The accuracy and efficiency of the sectional multicomponent aerosol model SEMA, described in the first part of this paper, are tested. Comparisons of results of an equilibrium version of SEMA with results of the equilibrium models SEQUILIB and AIM show good agreement for relative humidities above 60% and thus validate the thermodynamic portion of the model. Tests of the dynamic portion of SEMA ...

Precise patterning of dendritic arbors is critical for the wiring and function of neural circuits. Dendrite-extracellular matrix (ECM) adhesion ensures that the dendrites of Drosophila dendritic arborization (da) sensory neurons are properly restricted in a 2D space, and thereby facilitates contact-mediated dendritic self-avoidance and tiling. However, the mechanisms regulating dendrite-ECM adh...

Gradients of axon guidance molecules instruct the formation of continuous neural maps, such as the retinotopic map in the vertebrate visual system. Here we show that molecular gradients can also instruct the formation of a discrete neural map. In the fly olfactory system, axons of 50 classes of olfactory receptor neurons (ORNs) and dendrites of 50 classes of projection neurons (PNs) form one-to...

Neuropilins have recently been characterized as receptors for secreted semaphorins. Here, we report the generation of a dominant negative form of neuropilin-1 by the deletion of one of its extracellular domains. Expression of this variant in cultured primary sympathetic neurons blocks the paralysis of growth cone motility normally induced by SEMA-3A (collapsin-1, semaphorin III, semaphorin D) a...

Learning to read is very challenging for children with Autism Spectrum Disorders (ASD), but also very important, as it can give them access to new knowledge. This is even more challenging in minimally verbal children, who do not have the verbal abilities to learn through usual methods. To address the learning of literacy skills in French minimally verbal school-aged children with ASD, we design...

Although the detrimental effects of math anxiety in adults are well understood, few studies have examined how it affects younger children who are beginning to learn math in a formal academic setting. Here, we examine the relationship between math anxiety and math achievement in second and third graders. In response to the need for a grade-appropriate measure of assessing math anxiety in this gr...

Development professionals have deployed several mobile phone-based ICT (Information and Communications Technology) platforms in the global South for improving water, health, and education services. In this paper, we focus on a mobile phone-based ICT platform for water services, called Sensors, Empowerment and Accountability in Tanzania (SEMA), developed by our team in the context of an action r...

Peripheral nerve growth is regulated by the coordinated action of numerous external stimuli, including positively acting neurotrophin-derived growth cues and restrictive semaphorin cues. Here, we show that Semaphorin 3F (Sema 3F) can antagonize nerve growth factor (NGF)-stimulated TrkA (tyrosine receptor kinase A) signaling in sympathetic neurons, thereby apparently contributing to growth cone ...

Most axons in the CNS innervate specific subregions or layers of their target regions and form contacts with specific types of target neurons, but the molecular basis of this process is not well understood. To determine whether collapsin-1/semaphorin-III/D, a molecule known to repel specific axons, might guide afferent axons within their cerebellar targets, we characterized its expression by in...