Nonadaptive Fluctuation in an Adaptive Sensory System: Bacterial Chemoreceptor

BACKGROUND: Sensory systems often exhibit an adaptation or desensitization after a transient response, making the system ready to receive a new signal over a wide range of backgrounds. Because of the strong influence of thermal stochastic fluctuations on the biomolecules responsible for the adaptation, such as many membrane receptors and channels, their response is inherently noisy, and the adaptive property is achieved as a statistical average. METHODOLOGY/PRINCIPAL FINDINGS: Here, we study a simple kinetic model characterizing the essential aspects of these adaptive molecular systems and show theoretically that, while such an adaptive sensory system exhibits a perfect adaptation property on average, its temporal stochastic fluctuations are able to be sensitive to the environmental conditions. Among the adaptive sensory systems, an extensively studied model system is the bacterial receptor responsible for chemotaxis. The model exhibits a nonadaptive fluctuation sensitive to the environmental ligand concentration, while perfect adaptation is achieved on average. Furthermore, we found that such nonadaptive fluctuation makes the bacterial behavior dependent on the environmental chemoattractant concentrations, which enhances the chemotactic performance. CONCLUSIONS/SIGNIFICANCE: This result indicates that adaptive sensory systems can make use of such stochastic fluctuation to carry environmental information, which is not possible by means of the average, while keeping responsive to the changing stimulus

Hardware-Oriented Algorithm for Human Detection using GMM-MRCoHOG Features

In this research, we focus on Gaussian mixture model-multiresolution co-occurrence histograms of oriented gradients (GMM-MRCoHOG) features using luminance gradients in images and propose a hardware-oriented algorithm of GMM-MRCoHOG to implement it on a field programmable gate array (FPGA). The proposed method simplifies the calculation of luminance gradients, which is a high-cost operation in the conventional algorithm, by using lookup tables to reduce the circuit size. We also designed a human-detection digital architecture of the proposed algorithm for FPGA implementation using high-level synthesis. The verification results showed that the processing speed of the proposed architecture was approximately 123 times faster than that of the FPGA implementation of VGG-16.17th International Joint Conference on Computer Vision Theory and Applications (VISAPP 2022), February 6-8, 2022, Online Streamin

The renin–angiotensin system promotes arrhythmogenic substrates and lethal arrhythmias in mice with non-ischaemic cardiomyopathy

[Aims]The progression of pathological left ventricular remodelling leads to cardiac dysfunction and contributes to the occurrence of malignant arrhythmias and sudden cardiac death. The underlying molecular mechanisms remain unclear, however. Our aim was to examine the role of the renin–angiotensin system (RAS) in the mechanism underlying arrhythmogenic cardiac remodelling using a transgenic mouse expressing a cardiac-specific dominant-negative form of neuron-restrictive silencer factor (dnNRSF-Tg). This mouse model exhibits progressive cardiac dysfunction leading to lethal arrhythmias. [Methods and results]Subcutaneous administration of aliskiren, a direct renin inhibitor, significantly suppressed the progression of pathological cardiac remodelling and improved survival among dnNRSF-Tg mice while reducing arrhythmogenicity. Genetic deletion of the angiotensin type 1a receptor (AT1aR) similarly suppressed cardiac remodelling and sudden death. In optical mapping analyses, spontaneous ventricular tachycardia (VT) and fibrillation (VF) initiated by breakthrough-type excitations originating from focal activation sites and maintained by functional re-entry were observed in dnNRSF-Tg hearts. Under constant pacing, dnNRSF-Tg hearts exhibited markedly slowed conduction velocity, which likely contributes to the arrhythmogenic substrate. Aliskiren treatment increased conduction velocity and reduced the incidence of sustained VT. These effects were associated with suppression of cardiac fibrosis and restoration of connexin 43 expression in dnNRSF-Tg ventricles. [Conclusion]Renin inhibition or genetic deletion of AT1aR suppresses pathological cardiac remodelling that leads to the generation of substrates maintaining VT/VF and reduces the occurrence of sudden death in dnNRSF-Tg mice. These findings demonstrate the significant contribution of RAS activation to the progression of arrhythmogenic substrates

Rice Annotation Database (RAD): a contig-oriented database for map-based rice genomics

A contig-oriented database for annotation of the rice genome has been constructed to facilitate map-based rice genomics. The Rice Annotation Database has the following functional features: (i) extensive effort of manual annotations of P1-derived artificial chromosome/bacterial artificial chromosome clones can be merged at chromosome and contig-level; (ii) concise visualization of the annotation information such as the predicted genes, results of various prediction programs (RiceHMM, Genscan, Genscan+, Fgenesh, GeneMark, etc.), homology to expressed sequence tag, full-length cDNA and protein; (iii) user-friendly clone / gene query system; (iv) download functions for nucleotide, amino acid and coding sequences; (v) analysis of various features of the genome (GC-content, average value, etc.); and (vi) genome-wide homology search (BLAST) of contig- and chromosome-level genome sequence to allow comparative analysis with the genome sequence of other organisms. As of October 2004, the database contains a total of 215 Mb sequence with relevant annotation results including 30 000 manually curated genes. The database can provide the latest information on manual annotation as well as a comprehensive structural analysis of various features of the rice genome. The database can be accessed at http://rad.dna.affrc.go.jp/

Expression and localization of RLF/ INSL3 receptor RXFP2 in boar testes

This study investigated the possibility of the presence of specific receptor for relaxin-like factor (RLF)/insulin-like peptide 3 (INSL3) in boar testes. While RLF/INSL3 was produced by Leydig cells in the boar testis, its own receptor RXFP2 was expressed mainly in meiotic and post-meiotic germ cells, but not in Leydig cells, suggesting the existence of RLF/INSL3–RXFP2 signaling in germ cells of boars

AGN number fraction in galaxy groups and clusters at z < 1.4 from the Subaru Hyper Suprime-Cam survey

One of the key questions on active galactic nuclei (AGN) in galaxy clusters is how AGN could affect the formation and evolution of member galaxies and galaxy clusters in the history of the Universe. To address this issue, we investigate the dependence of AGN number fraction ($f_{\rm AGN}$) on cluster redshift ($z_{\rm cl}$) and distance from the cluster center ($R/R_{\rm 200}$). We focus on more than 27,000 galaxy groups and clusters at $0.1 < z_{\rm cl} < 1.4$ with more than 1 million member galaxies selected from the Subaru Hyper Suprime-Cam. By combining various AGN selection methods based on infrared (IR), radio, and X-ray data, we identify 2,688 AGN. We find that (i) $f_{\rm AGN}$ increases with $z_{\rm cl}$ and (ii) $f_{\rm AGN}$ decreases with $R/R_{\rm 200}$. The main contributors to the rapid increase of $f_{\rm AGN}$ towards high-$z$ and cluster center are IR- and radio-selected AGN, respectively. Those results indicate that the emergence of the AGN population depends on the environment and redshift, and galaxy groups and clusters at high-$z$ play an important role in AGN evolution. We also find that cluster-cluster mergers may not drive AGN activity in at least the cluster center, while we have tentative evidence that cluster-cluster mergers would enhance AGN activity in the outskirts of (particularly massive) galaxy clusters.Comment: 16 pages, 21 figures, and 2 tables, accepted for publication in PAS