Schizophrenia-associated somatic copy-number variants from 12,834 cases reveal recurrent NRXN1 and ABCB11 disruptions

While germline copy-number variants (CNVs) contribute to schizophrenia (SCZ) risk, the contribution of somatic CNVs (sCNVs)—present in some but not all cells—remains unknown. We identified sCNVs using blood-derived genotype arrays from 12,834 SCZ cases and 11,648 controls, filtering sCNVs at loci recurrently mutated in clonal blood disorders. Likely early-developmental sCNVs were more common in cases (0.91%) than controls (0.51%, p = 2.68e−4), with recurrent somatic deletions of exons 1–5 of the NRXN1 gene in five SCZ cases. Hi-C maps revealed ectopic, allele-specific loops forming between a potential cryptic promoter and non-coding cis-regulatory elements upon 5′ deletions in NRXN1. We also observed recurrent intragenic deletions of ABCB11, encoding a transporter implicated in anti-psychotic response, in five treatment-resistant SCZ cases and showed that ABCB11 is specifically enriched in neurons forming mesocortical and mesolimbic dopaminergic projections. Our results indicate potential roles of sCNVs in SCZ risk

Application of FRET Microscopy to the Study of the Local Environment and Dynamics of DNA SAMs on Au Electrodes

Immobilized DNA probe strands self-assembled on an electrode surface are the bases of many electrochemically based biosensors. Control or measurement of the local environment around each DNA molecule tethered to the electrode surface is needed because the local environment can influence the binding or hybridization efficiency of the target in solution. Measurement of this local environment in buffer or under electrochemical control can be challenging. Here we demonstrate the use of fluorescence microscopy and a Förster resonance energy transfer (FRET) methodology to characterize multicomponent DNA SAMs. The DNA SAMs that were studied were composed of a series of mole fraction ratios of alkylthiol-modified DNA which was labeled with either AlexaFluor488 or AlexaFluor647, a FRET donor and acceptor, respectively. The DNA SAMs were hybridized before assembly onto the electrode surface. Wide-field filter-based FRET microscopy was used to study the assembly of DNA SAMs onto gold bead electrodes. These single-crystal gold bead electrodes contain many surface crystallographic regions which enable the comparison of the adsorbed DNA local environment. These surfaces show that most surface modifications are uniformly prepared, and the FRET efficiency can be explained through simple surface density considerations. The FRET efficiency for different compositions of the donor and acceptor for these regions is also explained through 2D FRET modeling. Not all surfaces were similar to the (111) and (110) regions showing deviations from the expected FRET behavior. Also demonstrated is FRET imaging using a confocal microscope. This approach proves useful in the analysis of a more dynamic system, such as the analysis of reductive desorption of the mixed-component DNA SAM. FRET microscopy is useful for surface analysis of the DNA local environment, enabling a measure of the surface modification, local density, and clustering and eventually a new detection modality.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Potential Controls the Interaction of Liposomes with Octadecanol-Modified Au Electrodes: An in Situ AFM Study

The formation of supported lipid bilayers using liposomes requires interaction with the solid surface, rupture of the liposome, and spreading to cover the surface with a lipid bilayer. This can result in a less-than-uniform coating of the solid surface. Presented is a method that uses the electrochemical poration of an adsorbed lipid-like layer on a Au electrode to control the interaction of 100 nm DOPC liposomes. An octadecanol-coated Au-on-mica surface was imaged using tapping-mode AFM during the application of potential in the presence or absence of liposomes. When the substrate potential was made negative enough, defects formed in the adsorbed layer and new taller features were observed. More features were observed and existing features increased in size with time spent at this negative poration potential. The new features were 1.8–2.0 nm higher than the octadecanol-coated gold surface, half the thickness of a DOPC bilayer. These features were not observed in the absence of liposomes when undergoing the same potential perturbation. In the presence of liposomes, the application of a poration potential was needed to initiate the formation of these taller features. Once the applied potential was removed, the features stopped growing and no new regions were observed. The size of these new regions was consistent with the footprint of a flattened 100 nm liposome. It is speculated that the DOPC liposomes were able to interact with the defects and became soluble in the octadecanol, creating a taller region that was limited in size to the liposome that adsorbed and became incorporated. This AFM study confirms previous in situ fluorescence measurements of the same system and illustrates the use of a potential perturbation to control the formation of these regions of increased DOPC content

Electrodeposition of Aluminum onto Copper-Coated Printed Circuit Boards

The electrodeposition of aluminum thin films onto copper-coated printed circuit boards from aluminum chloride-trimethylphenylammonium chloride ionic liquids is studied. Various electrodeposition methods with different surface pretreatment procedures were investigated and compared to optimize the deposited aluminum morphology and properties. For the same amount of charge, a pulse current deposition approach applied at a low duty cycle of 10 % allowed the use of higher deposition current densities, leading to finer and more compact aluminum deposits compared with those produced by constant potential and constant current deposition techniques. Pulse current deposition with various peak current densities of −25 mA/cm2 to −65 mA/cm2 was conducted over a temperature range of 20 °C to 60 °C. At a moderate temperature of 40 °C, the electrodeposited aluminum layer was the most adherent. An increase of peak current density did not have an obvious effect on the deposit morphology, but it led to an increased amount of both deposited aluminum and incorporated impurities (oxygen and chloride). At room temperature, the electrical resistivity of the copper-coated printed circuit boards with deposited aluminum decreased as the peak current density for aluminum deposition increased.Applied Science, Faculty ofScience, Faculty ofNon UBCChemistry, Department ofMaterials Engineering, Department ofReviewedFacultyResearche

Redox-Controlled Energy Transfer Quenching of Fluorophore- Labeled DNA SAMs Enables In Situ Study of These Complex Electrochemical Interfaces

Interfaces modified by a molecular monolayer can be challenging to study, particularly in situ, requiring novel approaches. Coupling electrochemical and optical approaches can be useful when signals are correlated. Here we detail a methodology that uses redox electrochemistry to control surface-based fluorescence intensity for detecting DNA hybridization and studying the uniformity of the surface response. A mixed composition single-strand DNA SAM was prepared using potential-assisted thiol exchange with two alkylthiolmodified ssDNAs that were either labeled with a fluorophore (AlexaFluor488) or a methylene blue (MB) redox tag. A significant change in fluorescence was observed when reducing MB to colorless leuco-MB. In situ fluorescence microscopy on a single-crystal gold bead electrode showed that fluorescence intensity depended on (1) the potential controlling the oxidation state of MB, (2) the surface density of DNA, (3) the MB:AlexFluor488 ratio in the DNA SAM, and (4) the local environment around the DNA SAM. MB efficiently quenched AlexaFluor488 fluorescence. Reduction of MB showed a significant increase in fluorescence resulting from a decrease in quenching or energy transfer efficiency. Hybridization of DNA SAMs with its unlabeled complement showed a large increase in fluorescence due to MB reduction for surfaces with sufficient DNA coverage. Comparing electrochemical−fluorescence measurements to electrochemical (SWV) measurements showed an improvement in detection of a small fraction of hybridized DNA SAM for surfaces with optimal DNA SAM composition and coverage. Additionally, this coupled electrochemical redox-fluorescence microscopy method can measure the spatial heterogeneity of electron-transfer kinetics and the influence of the local interfacial environment.info:eu-repo/semantics/publishe