Thermodynamics for the Formation of Double-Stranded DNA-Single-Walled Carbon Nanotube Hybrids.

For the first time, the thermodynamics are described for the formation of double-stranded DNA (ds-DNA)-single-walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds-DNAs d(A)20 -d(T)20 and nuclear factor (NF)-κB decoy. UV/Vis/near-IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single-stranded DNAs (ss-DNAs), including d(A)20 and d(T)20, are also used for comparison. The d(A)20-d(T)20 shows a drastic change in its thermodynamic parameters around the melting temperature (Tm ) of the DNA oligomer. No such Tm dependency was measured, owing to high Tm in the NF-κB decoy DNA and no Tm in the ss-DNA.

Neuronal DSCAM regulates the peri-synaptic localization of GLAST in Bergmann glia for functional synapse formation.

In the central nervous system, astrocytes enable appropriate synapse function through glutamate clearance from the synaptic cleft; however, it remains unclear how astrocytic glutamate transporters function at peri-synaptic contact. Here, we report that Down syndrome cell adhesion molecule (DSCAM) in Purkinje cells controls synapse formation and function in the developing cerebellum. Dscam-mutant mice show defects in CF synapse translocation as is observed in loss of function mutations in the astrocytic glutamate transporter GLAST expressed in Bergmann glia. These mice show impaired glutamate clearance and the delocalization of GLAST away from the cleft of parallel fibre (PF) synapse. GLAST complexes with the extracellular domain of DSCAM. Riluzole, as an activator of GLAST-mediated uptake, rescues the proximal impairment in CF synapse formation in Purkinje cell-selective Dscam-deficient mice. DSCAM is required for motor learning, but not gross motor coordination. In conclusion, the intercellular association of synaptic and astrocyte proteins is important for synapse formation and function in neural transmission.

A de novo CHD3 variant in a child with intellectual disability, autism, joint laxity, and dysmorphisms.

BACKGROUND: Chromodomain helicase DNA-binding (CHD) proteins play important roles in developmental processes. CHD3, a member of the CHD family of proteins, was reported to be a cause of a neurodevelopmental syndrome by Snijders Blok et al., but only a small number of probands have been reported. CASE REPORT: The patient was a 9-year-old female with severe intellectual disability, speech impairment, autism, joint laxity and dysmorphisms. Whole exome sequencing revealed a de novo missense variant in CHD3 (NM_001005273:exon18: c.2896C > T:p.R966W). CONCLUSION: We report a case with a pathogenic variant in the CHD3 gene. Our report indicates that CHD3 analysis is helpful for diagnosis of the cases with neurodevelopmental disorders, joint laxity, and coarse facial phenotype.

DSCAM regulates delamination of neurons in the developing midbrain.

For normal neurogenesis and circuit formation, delamination of differentiating neurons from the proliferative zone must be precisely controlled; however, the regulatory mechanisms underlying cell attachment are poorly understood. Here, we show that Down syndrome cell adhesion molecule (DSCAM) controls neuronal delamination by local suppression of the RapGEF2-Rap1-N-cadherin cascade at the apical endfeet in the dorsal midbrain. Dscam transcripts were expressed in differentiating neurons, and DSCAM protein accumulated at the distal part of the apical endfeet. Cre-loxP-based neuronal labeling revealed that Dscam knockdown impaired endfeet detachment from ventricles. DSCAM associated with RapGEF2 to inactivate Rap1, whose activity is required for membrane localization of N-cadherin. Correspondingly, Dscam knockdown increased N-cadherin localization and ventricular attachment area at the endfeet. Furthermore, excessive endfeet attachment by Dscam knockdown was restored by co-knockdown of RapGEF2 or N-cadherin Our findings shed light on the molecular mechanism that regulates a critical step in early neuronal development.

A Mutation in the Tubulin-Encoding TUBB3 Gene Causes Complex Cortical Malformations and Unilateral Hypohidrosis.

Recent studies have emphasized the association between tubulin gene mutations and developmental abnormalities of the cortex. In this study, the authors identified a mutation in the tubulin-encoding class III ß-tubulin (TUBB3) gene in a 4-year-old boy presenting with brain abnormalities and unilateral hypohidrosis. The patient showed a left internal strabismus, moderate developmental delay, and congenital hypohidrosis of the right side of the body. Magnetic resonance imaging disclosed gyral disorganization mainly in the left perisylvian region, dysmorphic and hypertrophic basal ganglia with fusion between the putamen and caudate nucleus without affecting the anterior limb of the internal capsule, and moderate hypoplasia of the right brain stem and cerebellum. Diffusion tensor imaging studies revealed disorganization of the pyramidal fibers. The amplitude of the sympathetic skin response was low in the right arm, which led to a diagnosis of focal autonomic neuropathy. Sequencing the TUBB3 gene revealed a de novo missense mutation, c.862G>A (p.E288K).