The Unconserved Groucho Central Region Is Essential for Viability and Modulates Target Gene Specificity

Groucho (Gro) is a Drosophila corepressor required by numerous DNA-binding repressors, many of which are distributed in gradients and provide positional information during development. Gro contains well-conserved domains at its N- and C-termini, and a poorly conserved central region that includes the GP, CcN, and SP domains. All lethal point mutations in gro map to the conserved regions, leading to speculation that the unconserved central domains are dispensable. However, our sequence analysis suggests that the central domains are disordered leading us to suspect that the lack of lethal mutations in this region reflects a lack of order rather than an absence of essential functions. In support of this conclusion, genomic rescue experiments with Gro deletion variants demonstrate that the GP and CcN domains are required for viability. Misexpression assays using these same deletion variants show that the SP domain prevents unrestrained and promiscuous repression by Gro, while the GP and CcN domains are indispensable for repression. Deletion of the GP domain leads to loss of nuclear import, while deletion of the CcN domain leads to complete loss of repression. Changes in Gro activity levels reset the threshold concentrations at which graded repressors silence target gene expression. We conclude that co-regulators such as Gro are not simply permissive components of the repression machinery, but cooperate with graded DNA-binding factors in setting borders of gene expression. We suspect that disorder in the Gro central domains may provide the flexibility that allows this region to mediate multiple interactions required for repression

Crystal structure and density functional calculation of (E)-4-Hydroxy-3-methyl-N'- (thiophen-2-ylmethylene)-1,4-dihydroquinoxaline-2-carbohydrazide radical

The compound (E)-4-Hydroxy-3-methyl-N'-(thiophen-2-ylmethylene)-1,4-dihydroquinoxaline-2-carbohydrazide (C15H13N4O2S) is a stable free radical quinoxaline derivative. It was prepared by treatment of an acidified ethanolic solution of 3-methyl-2-(thiophen-2-ylmethylenehydrazinocarbonyl)quinoxaline-4-oxide with a solution of CuSO4.5H2O. The crystal structure shows that the molecule contains non-planar linking unit between quinoxaline and thiophene rings. Hydrogen bonding (N-H…O), π…π stacking and S…S intermolecular interactions may be effective in the stabilization of the crystal lattice. Density functional theory results agree well with X-ray experimental findings indicating that the free radical is indeed possible and that the stability of this compound might be attributed to the highly electron delocalization of the conjugation system over the whole compound along with the extra stabilization from the intramolecular interactions

The acute effects of mild traumatic brain injury on finger tapping with and without word repetition

This study aimed to investigate the acute effects of mild Traumatic Brain Injury (mTBI) on the performance of a finger tapping and word repetition dual task in order to determine working memory impairment in mTBI Sixty-four (50 male, 14 female) right-handed cases of mTBI and 26 (18 male and 8 female) right-handed cases of orthopaedic injuries were tested within 24 hours of injury. Patients with mTBI completed fewer correct taps in 10 seconds than patients with orthopaedic injuries, and female mTBI cases repeated fewer words. The size of the dual task decrement did not vary between groups. When added to a test battery including the Rapid Screen of Concussion (RSC; Comerford, Geffen, May, Medland T Geffen, 2002) and the Digit Symbol Substitution Test,finger tapping speed accounted for 1% of between groups variance and did not improve classification rates of male participants. While the addition of tapping rate did not improve the sensitivity and specificity of the RSC and DSST to mTBI in males, univariate analysis of motor performance in females indicated. that dual task performance might be diagnostic. An increase in female sample Size is warranted. These results confirm the view that there is a generalized slowing of processing ability following mTBI