Spin Berry phase in anisotropic topological insulators

Three-dimensional topological insulators are characterized by the presence of protected gapless spin helical surface states. In realistic samples these surface states are extended from one surface to another, covering the entire sample. Generally, on a curved surface of a topological insulator an electron in a surface state acquires a spin Berry phase as an expression of the constraint that the effective surface spin must follow the tangential surface of real space geometry. Such a Berry phase adds up to pi when the electron encircles, e.g., once around a cylinder. Realistic topological insulators compounds are also often layered, i.e., are anisotropic. We demonstrate explicitly the existence of such a pi Berry phase in the presence and absence (due to crystal anisotropy) of cylindrical symmetry, that is, regardless of fulfilling the spin-to-surface locking condition. The robustness of the spin Berry phase pi against cylindrical symmetry breaking is confirmed numerically using a tight-binding model implementation of a topological insulator nanowire penetrated by a pi-flux tube.Comment: 9 pages, 4 figures (6 panels

Weak topological insulator with protected gapless helical states

A workable model for describing dislocation lines introduced into a three-dimensional topological insulator is proposed. We show how fragile surface Dirac cones of a weak topological insulator evolve into protected gapless helical modes confined to the vicinity of dislocation line. It is demonstrated that surface Dirac cones of a topological insulator (either strong or weak) acquire a finite-size energy gap, when the surface is deformed into a cylinder penetrating the otherwise surface-less system. We show that when a dislocation with a non-trivial Burgers vector is introduced, the finite-size energy gap play the role of stabilizing the one-dimensional gapless states.Comment: 8 pages, 17 figure

Disruption of Metal Homeostasis and the Pathogenesis of Prion Diseases

Prion diseases are progressive neurodegenerative diseases that are associated with the conformational conversion of normal cellular prion protein (PrPC) into abnormal pathogenic prion protein (PrPSc). PrPC is a metal‐binding protein that is located in the synapse and possesses the ability to bind to various metals, including Cu, Zn, Mn and Fe. Moreover, increasing evidence suggests that PrPC plays essential roles in the maintenance of metal homeostasis in the synapse. Trace elements have a crucial influence on the conformational change of PrPC. Given that other disease‐related proteins such as β‐amyloid protein and its precursor protein (APP) in Alzheimer\u27s disease also exist in the synapse and possess a metal‐binding ability, an interaction between PrP and metals and between PrP and APP, may occur in the synapse; the resulting metal homeostasis may lead to the pathogenesis of prion diseases. Here, we review our studies and other new findings that inform the current understanding of the link between trace elements and physiological functions of PrPC and the neurotoxicity of PrPSc

Defoliating to 12-15 leaves increases calcium concentration and decreases blossom-end rot incidence in fruit of tomato plant grown under moderate water stress

The objectives of this study were to (i) determine the optimum number of whole leaves to retain on a tomato plant for effective blossom-end rot (BER) management and (ii) explore the relationship between shoot calcium (Ca) and fruit Ca in non-defoliated plants in two different sized fruit cultivars, a large-fruited cultivar ‘Momotaro fight’ and a medium-fruited cultivar ‘Cindy sweet’. Treatments involved maintaining 18, 15 and 12 leaves on a plant. All lateral shoots were removed regularly throughout the growing period except the shoot closest to the flowering truss in the 18-leaf treatment. At the length of 10cm, these shoots were sampled for real time Ca determination using a hand held Ca2+ meter. In the plants defoliated to 18 leaves, BER was higher in ‘Momotaro fight’ at 10% compared to 2% in ‘Cindy sweet’. Fruit growth rate was significantly increased by defoliation in ‘Momotaro fight’, however no significant difference was observed among treatments in ‘Cindy sweet’. Defoliating to 12 leaves increased daily Ca transport rate by 59% and 37% in ‘Momotaro fight’ and ‘Cindy sweet’, respectively. Defoliating to 12 leaves increased the water-soluble Ca concentration in the distal part of fruit by 34% and 14% in ‘Momotaro fight’ and ‘Cindy sweet’, respectively. In the plants defoliated to 18 leaves where only old yellowish leaves were removed, a significant steady decrease was observed in the concentration of water soluble Ca in the distal part of fruit with increase in truss order. There was a significant linear relationship between water-soluble Ca concentration in the distal part of the fruit and Ca concentration in the lateral shoot of plants defoliated to 18 leaves. We conclude that under moderate water stress by root zone restriction and also certain other BER inductive conditions, defoliation to 12–15 leaves on a tomato plant should be a promising approach for decreasing BER incidence in susceptible large fruit cultivars

トウガラシ（Capsicum baccatum）における カプサイシノイド含量の変異とその非辛味系統

The chili pepper (Capsicum) is both an important spice and fresh vegetable worldwide. C. baccatum is a lesser known domesticated species that is native to the Andean region. Fruit traits such as color, shape, and pungency markedly vary in this species. C. baccatum has potential as a bioresource for future chili pepper breeding programs. Although extensive studies have been conducted on the pungency of C. annuum, that of C. baccatum has not been examined in as much detail. In the present study, capsaicinoid contents were analyzed in 36 C. baccatum accessions. Capsaicinoid contents ranged between 0 and 4,258 μg/gDW. Furthermore, a negative relationship was observed between capsaicinoid contents and fruit weights. Although the pungency of C. baccatum is regarded as low-mild, very few non-pungent accessions were detected ; only one non-pungent accession (‘Kaleidoscope’) was identified among the C. baccatum accessions examined. In order to validate the stability of non-pungency in the accession, capsaicinoid contents were determined at different harvest dates, along with other accessions with different pungencies. Although capsaicinoid contents in other C. baccatum accessions changed with the picking date, capsaicinoid was not detected in ‘Kaleidoscope’ at any date. The non-pungent accession reported here may be useful for future C. baccatum pepper breeding programs.　トウガラシ（Capsicum 属）は世界的に重要な香辛料および野菜である．C. baccatum は南米原産のマイナーな栽培種であるが，果色，果形や辛味など果実形質に多様性が認められることから，トウガラシ遺伝資源として注目されている．トウガラシの辛味性についてはC. annuum 種において多くの研究が行われているが，C. baccatum 種においては十分研究されていない． 　本研究では，C. baccatum 36系統について辛味成分カプサイシノイドの含量を調査した．カプサイシノイド含量の幅は0 ～4,258 ㎍ /gDW であった．また果実重と辛味成分含量の間に負の相関が認められた．C. baccatum の辛味は低〜中程度であるが，非辛味系統はほとんど認められず，唯一1 系統（‘Kaleidoscope’）が非辛味であった．この非辛味の安定性を調査するために，辛味程度の異なる系統とともに異なる収穫時期におけるカプサイシノイド含量を調査した． 　他のC. baccatum 系統ではカプサイシノイド含量は収穫時期で変化したが，‘Kaleidoscope’ ではいずれの収穫時期でもカプサイシノイドは検出されなかった．本研究で見出された非辛味系統は将来のC. baccatum の育種において有用であろう

Fasciation in Strawberry Floral Organs and Possible Implications for Floral Transition

Fasciation in strawberry is characterized by an enlarged and flattened receptacle, clustering of flowers, and altered inflorescence architecture. However, the developmental process of fasciated flowers remains obscure. In this study, the fasciation incidence and developmental process in the primary fruit and inflorescence architecture were evaluated and compared for the non-susceptible cultivars, ‘Nyoho’ and ‘Sagahonoka’ and one of the most susceptible cultivars, ‘Ai-Berry’. The severity and frequency of flower and inflorescence fasciation was clearly greater in the vigorously growing large plants of ‘Ai-Berry’ compared to small plants and large plants of the other two cultivars. In ‘Ai-Berry’, the deformation of the large shoot apical meristem (SAM) into an oval shape was the initial symptom observed before and during floral transition. Such oval-shaped SAMs often differentiated two or more leaf primordia almost at the same time, which then developed into divided multiple vegetative SAMs before floral transition and linearly-fasciated SAMs during floral transition, respectively. The development of fasciation symptoms was observed after downregulation of FaTFL1. Although inflorescence or receptacle fasciation could be controlled when early and rapid floral induction was achieved by intermittent low-temperature treatment, severe fasciation was observed in late-flowered plants which were either not responsive or not subjected to this treatment. These results indicate that fasciation of floral organs may be triggered and develop during floral transition and that temperature fluctuations around boundary values between floral inhibition to induction may cause a half-finished or slowly processed floral transition and finally result in severe fasciation in vigorously growing ‘Ai-Berry’ plants

Effect of seed cold PEG–priming concentration and period followed by re–drying on germination, growth and flowering of Eustoma grandiflorum （Raf.） Shinn ʻExe Lavenderʼ

This study aimed to investigate whether seed cold priming by PEG‒6000, followed by re‒drying would affect the germination, growth, and flowering of Eustoma ‘Exe Lavender’ raised seedling under high temperatures. Seeds of control treatment were not treated with cold‒priming or re‒drying. In experiment 1, seeds were cold‒primed with water and PEG‒6000 at ‒0.75 and ‒1.5 MPa for 5 weeks at 10°C in the dark and then subjected to re‒dried and storage for 30 days at 10°C. The results showed that cold‒primed seeds germinated earlier than those of the control. Compared to water treatment, plants grown from PEG‒6000 treatments and re‒drying showed similar germination rate, bolting rate, days to bolting, bolting node and flowering rate. In experiment 2, cold priming periods by water and ‒1.5 MPa PEG‒6000 were investigated for 4, 5, 6, 7, and 8 weeks. ‘Exe Lavender’ seeds treated with cold water and in the dark for longer than 5 weeks increased their percentage of radicle emergence and decreased germination rate after 30 days of re‒drying and storage. Meanwhile, those treated with cold-PEG did not protrude the radicle even for 8 weeks of priming and maintained the germination rate after re‒drying and storage. Days to bolting and days to flowering tended to decrease when the priming period decreased. The results suggest that the seed cold priming treatment by ‒1.5 MPa PEG‒6000 and subsequent re‒drying improved germination rate and maintained bolting rate and flowering rate in Eustoma compared to cold priming treatment by water raised seedling under high temperature conditions