Role of the SWI/SNF Chromatin Remodelling Complex in the Axon Development of the Drosophila Mushroom Body

The SWI/SNF complex is an evolutionarily conserved ATP-dependent chromatin remodelling complex that has been implicated in the aetiology of intellectual disability (ID). Among the dominant ID genes, the SWI/SNF complex is the most highly enriched protein complex. However, its role in the nervous system is not yet understood. I systematically investigated the role of this complex in the development of the Drosophila mushroom body (MB), a complex brain structure required for learning and memory. Gross MB morphology was assessed using confocal microscopy to identify morphological defects following RNAi-mediated knockdown of the 15 individual SWI/SNF genes in the MB. Knockdown of several SWI/SNF genes resulted in morphological abnormalities that suggest a role for this protein complex in axon remodelling. These findings reveal a novel role for the SWI/SNF complex in axon development and pave the way for understanding the underlying gene regulatory mechanisms

Regulation of Arabidopsis TGA transcription factors by cysteine residues : implication for redox control

The Arabidopsis TGA family of basic leucine zipper transcription factors regulate the expression of pathogenesis-related genes and are required for resistance to disease. Members of the family possess diverse properties in respect to their ability to transactivate and interact with NPR1, the central regulator of systemic acquired resistance in Arabidopsis. Two TGA factors, TGA1 and TGA2, have 83 % amino acid similarity but possess differing properties. TGA1 does not interact with NPR1 but is able to transactivate, while TGA2 interacts with NPR1 but is unable to transactivate. This study uses these two TGA factors to identify amino acids that are responsible for their function. Four cysteines residues within TGA1 were targeted for study by site-directed mutagenesis and the resulting mutants were tested for interaction with NPR1 in yeast. The construct containing a mutation of cysteine 260 (Cys-260) interacted well with NPR1, while those with mutations at Cys-172 or Cys-266 interacted poorly. The Cys-260 mutant also displayed the greatest decrease in transactivation potential in yeast, while mutation of Cys-172 or Cys-266 resulted in smaller decreases. Mutation of Cys-287 had no effect on NPR1 interaction or transactivation. Combining various point mutations in a single protein did not increase NPR1 interaction or transactivation levels, indicating that Cys-260 is crucial for regulating TGA1 properties. Cysteines possess the unique ability of forming reversible disulfide bonds which have been shown to regulate several mammalian cellular processes. The observation that mutation of a single TGA1 cysteine (Cys-260) greatly alters the protein’s properties provides a convincing argument that oxidoreduction of this residue is important for its regulation, possibly through the formation of a disulfide bond with either Cys-172 or Cys-266. To test whether other members of the TGA family could be regulated by oxidoreduction, several TGA2 constructs were created that introduced Cys at positions corresponding to those found in TGA1. When tested in yeast none were able to transactivate but continued to interact with NPR1

Software framework for geophysical data processing, visualization and code development

IGeoS is an integrated open-source software framework for geophysical data processing under development at the UofS seismology group. Unlike other systems, this processing monitor supports structured multicomponent seismic data streams, multidimensional data traces, and employs a unique backpropagation execution logic. This results in an unusual flexibility of processing, allowing the system to handle nearly any geophysical data. In this project, a modern and feature-rich Graphical User Interface (GUI) was developed for the system, allowing editing and submission of processing flows and interaction with running jobs. Multiple jobs can be executed in a distributed multi-processor networks and controlled from the same GUI. Jobs, in their turn, can also be parallelized to take advantage of parallel processing environments such as local area networks and Beowulf clusters. A 3D/2D interactive display server was created and integrated with the IGeoS geophysical data processing framework. With introduction of this major component, the IGeoS system becomes conceptually complete and potentially bridges the gap between the traditional processing and interpretation software. Finally, in a specialized application, network acquisition and relay components were written allowing IGeoS to be used for real-time applications. The completion of this functionality makes the processing and display capabilities of IGeoS available to multiple streams of seismic data from potentially remote sites. Seismic data can be acquired, transferred to the central server, processed, archived, and events picked and placed in database completely automatically

Active Topological Glass Confined within a Spherical Cavity

[Image: see text] We study active topological glass under spherical confinement, allowing us to exceed the chain lengths simulated previously and determine the critical exponents of the arrested conformations. We find a previously unresolved “tank-treading” dynamic mode of active segments along the ring contour. This mode can enhance active–passive phase separation in the state of active topological glass when both diffusional and conformational relaxation of the rings are significantly suppressed. Within the observational time, we see no systematic trends in the positioning of the separated active domains within the confining sphere. The arrested state exhibits coherent stochastic rotations. We discuss possible connections of the conformational and dynamic features of the system to chromosomes enclosed in the nucleus of a living cell

Noncancer comparators in cancer survivorship studies

In their article on new directions in cancer and aging, Kobayashi et al discuss the important issue of control selection in cancer survivorship studies. As in all areas of epidemiology and health services research, the scientific question should drive the choice of comparison groups. We believe that it is helpful to consider the comparators needed to address 3 distinct types of survivorship questions