Contrary to our knowledge of the genetic control of midline crossing, the mechanisms that generate and maintain the longitudinal axon pathways of the Drosophila CNS are largely unknown. The longitudinal pathways are formed by ipsilateral pioneer axons and the longitudinal glia. The longitudinal glia dictate these axonal trajectories and provide trophic support to later projecting follower neuro...

The midline glial cells are required for correct formation of the axonal pattern in the embryonic ventral nerve cord of Drosophila. Initially, six midline cells form an equivalence group with the capacity to develop as glial cells. By the end of embryonic development three to four cells are singled out as midline glial cells. Midline glia development occurs in two steps, both of which depend on...

Development of the Drosophila CNS midline cells is dependent upon the function of the single-minded (sim) gene. Sequence analysis shows that sim is a member of the basic-helix-loop-helix class of transcription factors. Cell fate experiments establish that sim is required for early events in midline cell development, including a synchronized cell division, proper formation of nerve cell precurso...

The shadow enhancer of the short gastrulation (sog) gene directs its sequential expression in the neurogenic ectoderm and the ventral midline of the developing Drosophila embryo. Here, we characterize three unusual features of the shadow enhancer midline activity. First, the minimal regions for the two different enhancer activities exhibit high overlap within the shadow enhancer, meaning that o...

In the grasshopper CNS, serotonergic growth cones cross the midline early in development and initiate expression of serotonin uptake activity, or SERT. To test if the midline contains an activity that induces SERT, cuts were made that separated serotonergic cell bodies from the midline. SERT activity is completely lost when the midline is separated but is then rescued by bath-applied FGF2 (fibr...

PURPOSE The purpose of this article is to determine whether certain facial asymmetries (nose and chin) have an impact on the perception of the maxillary dental midline shift. MATERIALS AND METHODS From a digitally created symmetric facial model (SFM) constructed in a previous study, a new asymmetric facial model (AFM) was created, with nose and chin deviated to the same side. Modifications we...

We have explored the direct and indirect radiative effects on climate of organic particles likely to have been present on early Earth by measuring their hygroscopicity and cloud nucleating ability. The early Earth analog aerosol particles were generated via ultraviolet photolysis of an early Earth analog gas mixture, which was designed to mimic possible atmospheric conditions before the rise of...

In Drosophila, Slit at the midline activates Robo receptors on commissural axons, thereby repelling them out of the midline into distinct longitudinal tracts on the contralateral side of the central nervous system. In the vertebrate spinal cord, Robo1 and Robo2 are expressed by commissural neurons, whereas all three Slit homologs are expressed at the ventral midline. Previous analysis of Slit1;...

The single-minded (sim) gene of Drosophila encodes a nuclear protein that plays a critical role in the development of the neurons, glia, and other nonneuronal cells that lie along the midline of the embryonic CNS. Using distinct cell fate markers, we observe that in sim mutant embryos the midline cells fail to differentiate properly into their mature CNS cell types and do not take their appropr...

BACKGROUND AND PURPOSE Hemicraniectomy is a decompressive surgery used to remove a large bone flap to allow edematous brain tissue to bulge extracranially. However, early indicators of the decompressive effects of hemicraniectomy are unclear. We investigated whether reduction of midline shift following hemicraniectomy is associated with improved consciousness and survival in patients with malig...