PARN-like Proteins Regulate Gene Expression in Land Plant Mitochondria by Modulating mRNA Polyadenylation

Mitochondria have their own double-stranded DNA genomes and systems to regulate transcription, mRNA processing, and translation. These systems differ from those operating in the host cell, and among eukaryotes. In recent decades, studies have revealed several plant-specific features of mitochondrial gene regulation. The polyadenylation status of mRNA is critical for its stability and translation in mitochondria. In this short review, I focus on recent advances in understanding the mechanisms regulating mRNA polyadenylation in plant mitochondria, including the role of poly(A)-specific ribonuclease-like proteins (PARNs). Accumulating evidence suggests that plant mitochondria have unique regulatory systems for mRNA poly(A) status and that PARNs play pivotal roles in these systems

Monte Carlo Calculation of Neutrons Transmitted through Matter

The neutron Monte Carlo code, CYGNUS, which is written in Fortran IV has been shown. This code can easily be used for several limitted geometries and requires considerably less computing time than O5R. In this paper, two methods of calculation are described : one by weight method and the other by collision density method, and the two techniques for determination of the anisotropic scattering angle in the center-of-mass system, i.e., Legendre expansion and Coveyou technique, and the method for determination of the excited level in the inelastic scattering are also described. The results calculated with CYGNUS code are compared with the numerical solution by PALLAS code for the sealer flux in water and graphite spheres, and with experimental spectra for the angular neutron flux in water and iron shields. The agreement obtained between the CYGNUS calculations and numerical or experimental results is good

Topology optimal design for optical waveguides using time domain beam propagation method

New topology optimal design approach for optical waveguide devices using a time domain beam propagation method (TD–BPM) is presented. A sensitivity analysis method for topology optimization using TD–BPM is formulated based on an adjoint variable method (AVM). A density method is used as a way to represent refractive index distribution. As design examples, a loss–reduced bending waveguide and a reflector are designed. It is confirmed that our design approach can surely enhance the performance of optical waveguide devices