modeling-myotonic-dystrophy-1-in-c2c12-myoblast-cells

Modeling Myotonic Dystrophy 1 in C2C12 Myoblast Cells

Myotonic dystrophy 1 (DM1) is a common form of muscular dystrophy. Although several animal models have been established for DM1, myoblast cell models are ...

University of Houston

We report the design, fabrication, and measurement of a microwave triple-band absorber. The compact single unit cell consists of three nested electric closed-ring resonators and a metallic ground plane separated by a dielectric layer. Simulation and experimental results show that the absorber has three distinctive absorption peaks at frequencies 4.06 GHz, 6.73 GHz, and 9.22 GHz with the absorption rates of 0.99, 0.93, and 0.95, respectively. The absorber is valid to a wide range of incident angles for both transverse electric (TE) and transverse magnetic (TM) polarizations. The triple-band absorber is a promising candidate as absorbing elements in scientific and technical applications because of its multiband absorption, polarization insensitivity, and wide-angle response.

Polarization-independent wide-angle triple-band metamaterial absorber.

Surface plasmon polaritons (SPPs) are localized surface electromagnetic waves that propagate along the interface between a metal and a dielectric. Owing to their inherent subwavelength confinement, SPPs have a strong potential to become building blocks of a type of photonic circuitry built up on 2D metal surfaces; however, SPPs are difficult to control on curved surfaces conformably and flexibly to produce advanced functional devices. Here we propose the concept of conformal surface plasmons (CSPs), surface plasmon waves that can propagate on ultrathin and flexible films to long distances in a wide broadband range from microwave to mid-infrared frequencies. We present the experimental realization of these CSPs in the microwave regime on paper-like dielectric films with a thickness 600-fold smaller than the operating wavelength. The flexible paper-like films can be bent, folded, and even twisted to mold the flow of CSPs.

Conformal surface plasmons propagating on ultrathin and flexible films.

We present the occurrence of bright modes and dark modes in spoof localized surface plasmons (LSPs) generated by ultrathin corrugated metallic disks. As two such disks with asymmetric geometries are placed in close proximity, we find that dark modes (in multipoles) of one disk emerge by coupling with the bright modes (in dipoles) of the other disk. Then we further observe multiple Fano resonances due to destructive interferences of dark modes with the overlapping and broadened bright modes. These Fano line-shapes clearly exhibit the strong polarization dependence. We design and fabricate the ultrathin corrugated bi-disk structure in the microwave frequency, and the measurement results show reasonable agreement with theoretical predictions and numerical simulations. Such multiple Fano resonances could be exploited for the plasmonic devices at lower frequencies.

Multiple Fano resonances in spoof localized surface plasmons.

It has been demonstrated that an ultrathin uniformly corrugated metallic strip is a good plasmonic waveguide in microwave and terahertz frequencies to propagate spoof surface plasmon polaritons (SPPs) with well confinement and small loss (Shen et al., PNAS 110, 40-45, 2013). Here, we propose a simple method to trap SPP waves on the ultrathin corrugated metallic strips in broad band in the microwave frequencies. By properly designing non-uniform corrugations with gradient-depth grooves, we show that the SPP waves are slowed down gradually and then reflected at pre-designed positions along the ultrathin metallic strip when the frequency varies. We design and fabricate the ultrathin gradient-corrugation metallic strip on a thin dielectric film. Both numerical simulation and measurement results validate the efficient trapping of SPP waves in broadband from 9 to 14 GHz. This proposal is a promising candidate for slow-wave devices in both microwave and terahertz regimes.

Trapping surface plasmon polaritons on ultrathin corrugated metallic strips in microwave frequencies.

We theoretically demonstrated and experimentally verified high-order radial spoof localized surface plasmon resonances supported by textured metal particles. Through an effective medium theory and exact numerical simulations, we show the emergence of these geometrically-originated electromagnetic modes at microwave frequencies. The occurrence of high-order radial spoof plasmon resonances is experimentally verified in ultrathin disks. Their spectral and near-field properties are characterized experimentally, showing an excellent agreement with theoretical predictions. Our findings shed light into the nature of spoof localized surface plasmons, and open the way to the design of broadband plasmonic devices able to operate at very different frequency regimes.

High-order localized spoof surface plasmon resonances and experimental verifications.

Myotonic dystrophy is a neuromuscular disease of RNA toxicity. The disease gene DMPK harbors expanded CTG trinucleotide repeats on its 3'-UTR. The transcripts of this mutant DMPK led to misregulation of RNA-binding proteins including MBNL1 and Celf1. In myoblasts, CUG-expansion impaired terminal differentiation. In this study, we formally tested how the abundance of Celf1 regulates normal myocyte differentiation, and how Celf1 expression level mediates CUG-expansion RNA toxicity-triggered impairment of myocyte differentiation. As the results, overexpression of Celf1 largely recapitulated the defects of myocytes with CUG-expansion, by increasing myocyte cycling. Knockdown of endogenous Celf1 level led to precocious myotube formation, supporting a negative connection between Celf1 abundance and myocyte terminal differentiation. Finally, knockdown of Celf1 in myocyte with CUG-expansion led to partial rescue, by promoting cell cycle exit. Our results suggest that Celf1 plays a distinctive and negative role in terminal myocyte differentiation, which partially contribute to DM1 RNA toxicity. Targeting Celf1 may be a valid strategy in correcting DM1 muscle phenotypes, especially for congenital cases.

Celf1 regulates cell cycle and is partially responsible for defective myoblast differentiation in myotonic dystrophy RNA toxicity.

By means of first-principles DFT computations, we systematically investigate the geometries, stabilities, electronic and magnetic properties of fully and partially hydrogenated zigzag BNC nanoribbons (fH-zBNCNRs and pH-zBNCNRs) with interfacial N-C or B-C connections. It is revealed that in the lowest-lying configuration of hybrid fH-zBNCNRs, the constituent C and BN segments can possess respective chair and boat conformations and both of them are connected by the chair mode, independent of the N-C/B-C interface. Changing the ribbon width and the ratio of BN to C can endow these fH-zBNCNR systems with abundant electronic and magnetic properties involving nonmagnetic (NM) semiconductivity, ferromagnetic (FM) metallicity, antiferromagnetic (AFM) metallicity as well as AFM half-metallicity. Besides, manipulating the hydrogenation pattern and ratio can also result in rich electronic and magnetic behaviors in pH-zBNCNRs, where NM semiconductivity, AFM semiconductivity, AFM metallicity and even AFM spin gapless semiconductor are observed. Additionally, the origin of the magnetism in these hydrogenated zBNCNRs is analyzed in detail. Finally, all of these hydrogenated BNC structures can possess a favorable formation energy, large binding energy per hydrogen atom and high thermal stability, indicating the great possibility of their experimental realization by hydrogenating pristine zBNCNRs. These valuable insights can be advantageous for promoting hybrid BNC-based nanomaterials in the applications of spintronics and multifunctional nanodevices.

Realizing diverse electronic and magnetic properties in hybrid zigzag BNC nanoribbons via hydrogenation.

We investigated the electronic properties and second hyperpolarizabilities of hydrogenated silicon nanoclusters (H-SiNCs) by using the density functional theory method. The effects of cluster size, external electric field and incident frequency on the second hyperpolarizability were also examined, respectively. We found that small H-SiNCs exhibit large second hyperpolarizability. With the increase of the number of silicon atoms in H-SiNCs, the frontier molecular orbital energy gap decreases, attributed to the enhancement of the second hyperpolarizability. Interestingly, we also found the electric-field-induced gigantic enhancement of the second hyperpolarizability for H-SiNCs due to the change of electron density distributions. In addition, our results demonstrate a significant dependence on the frequency of incident light.

Xiaopeng Shen

Department of Biology and Biochemistry

University of Houston

Modeling Myotonic Dystrophy 1 in C2C12 Myoblast Cells