Genetic basis of lineage-specific evolution of fruit traits in hexaploid persimmon

Frequent polyploidization events in plants have led to the establishment of many lineage-specific traits representing each species. Little is known about the genetic bases for these specific traits in polyploids, presumably due to plant genomic complexity and their difficulties in applying genetic approaches. Hexaploid Oriental persimmon (Diospyros kaki) has evolved specific fruit characteristics, including wide variations in fruit shapes and astringency. In this study, using whole-genome diploidized/quantitative genotypes from ddRAD-Seq data of 173 persimmon cultivars, we examined their population structures and potential correlations between their structural transitions and variations in nine fruit traits. The population structures of persimmon cultivars were highly randomized and not substantially correlated with the representative fruit traits focused on in this study, except for fruit astringency. With genome-wide association analytic tools considering polyploid alleles, we identified the loci associated with the nine fruit traits; we mainly focused on fruit-shape variations, which have been numerically characterized by principal component analysis of elliptic Fourier descriptors. The genomic regions that putatively underwent selective sweep exhibited no overlap with the loci associated with these persimmon-specific fruit traits. These insights will contribute to understanding the genetic mechanisms by which fruit traits are independently established, possibly due to polyploidization events

bFGF Regulates PI3-Kinase-Rac1-JNK Pathway and Promotes Fibroblast Migration in Wound Healing

Fibroblast proliferation and migration play important roles in wound healing. bFGF is known to promote both fibroblast proliferation and migration during the process of wound healing. However, the signal transduction of bFGF-induced fibroblast migration is still unclear, because bFGF can affect both proliferation and migration. Herein, we investigated the effect of bFGF on fibroblast migration regardless of its effect on fibroblast proliferation. We noticed involvement of the small GTPases of the Rho family, PI3-kinase, and JNK. bFGF activated RhoA, Rac1, PI3-kinase, and JNK in cultured fibroblasts. Inhibition of RhoA did not block bFGF-induced fibroblast migration, whereas inhibition of Rac1, PI3-kinase, or JNK blocked the fibroblast migration significantly. PI3-kinase-inhibited cells down-regulated the activities of Rac1 and JNK, and Rac1-inhibited cells down-regulated JNK activity, suggesting that PI3-kinase is upstream of Rac1 and that JNK is downstream of Rac1. Thus, we concluded that PI3-kinase, Rac1, and JNK were essential for bFGF-induced fibroblast migration, which is a novel pathway of bFGF-induced cell migration

Common mechanism for helical nanotube formation by anodic polymerization and by cathodic deposition using helical pores on silicon electrodes

We report that platinum-assisted chemical etching formed self-organized helical pores in silicon substrates can be utilized as platforms for the electrochemical production of nanohelices of conducting polymers (polypyrrole) and metals (gold). Surprisingly, the nanohelices thus created are tubes although the polymerization and deposition were carried out by anodic and cathodic reactions, respectively. Based on our results, we propose a common mechanism for the formation of tubular nanohelices by both anodic polymerization and cathodic deposition through the accumulation of reactants in microporous silicon which covers the wall surface of the helical pores

Structural dynamics and stability of corticocortical and thalamocortical axon terminals during motor learning.

Synaptic plasticity is the cellular basis of learning and memory. When animals learn a novel motor skill, synaptic modifications are induced in the primary motor cortex (M1), and new postsynaptic dendritic spines relevant to motor memory are formed in the early stage of learning. However, it is poorly understood how presynaptic axonal boutons are formed, eliminated, and maintained during motor learning, and whether long-range corticocortical and thalamocortical axonal boutons show distinct structural changes during learning. In this study, we conducted two-photon imaging of presynaptic boutons of long-range axons in layer 1 (L1) of the mouse M1 during the 7-day learning of an accelerating rotarod task. The training-period-averaged rate of formation of boutons on axons projecting from the secondary motor cortical area increased, while the average rate of elimination of those from the motor thalamus (thalamic boutons) decreased. In particular, the elimination rate of thalamic boutons during days 4-7 was lower than that in untrained mice, and the fraction of pre-existing thalamic boutons that survived until day 7 was higher than that in untrained mice. Our results suggest that the late stabilization of thalamic boutons in M1 contributes to motor skill learning

MELASにおける血液脳関門構成細胞と神経細胞のミトコンドリア形態の差異 ; 毛細血管内皮細胞の閉鎖結合開放による神経保護の関与

医学部小児科学教室　大澤眞木子教授退任記念特別

ACS Appl. Mater. Interfaces

Nanometric chiral objects such as twisted or helical nanoribbons represent a new class of objects having important potential in a large panel of applications, taking advantage, for example, of electromechanical or optical chirality, local chiral environment for catalysis, and chiral recognition. Supramolecular chemistry has played a central role in the production of such structures through either chiral macromolecules/foldamers or the self-assembly of chiral molecules; the latter can also be used as templates for the sol-gel transcription to silica materials, offering them polymorphisms with further structural stability. Here, we report a totally different and dynamic approach to produce helical mesostructures. This study focuses on helical nanopores that are spontaneously formed in the platinum-assisted chemical etching of silicon by dynamic self-organization under a nonequilibrium state. The symmetry breaking of a helical nanopore formation is achieved by the spatial symmetry breaking of a spatiotemporal pattern at the nanoscale and without incorporation of chiral molecules. Rotational motion of the platinum nanocatalyst, which is regarded as a spatiotemporal pattern at the etching frontier (the platinum/silicon interface), induces precession movement of the nanocatalyst, and movement of the catalyst during etching forms helical nanopores in the silicon. We consider that this study is an important milestone to understand the close relation between spatiotemporal pattern formation and the dynamic emergence of symmetry breaking in chemical reactions