Numerical analysis of double-diffusive convection in a porous enclosure due to opposing heat and mass fluxes on the vertical walls - Why does peculiar oscillation occur?

金沢大学環日本海域環境研究センターエコテクノロジー研究部門Peculiar oscillating convection is observed when two-dimensional double-diffusive convection in porous medium is analysed numerically. The top and bottom walls of an enclosure are insulated, and constant and opposing heat and mass fluxes are prescribed on the vertical walls. The peculiar oscillations are of three types: (1) Chaotic oscillations wherein the main flow is due to temperature; however, the convection due to concentration is strong enough to generate this peculiar oscillation. (2) The \u27sudden steady state case\u27 caused by the shifts from thermally-driven to concentration-driven forces. (3) The \u27re-oscillation case\u27 caused by the convection pattern changes from centrosymmetric to non-centrosymmetric.. © 2007 Elsevier Ltd. All rights reserved

Preliminary report on the molecular phylogeny of the Laurencia complex (Rhodomelaceae)

A molecular phylogenetic analysis of three closely related red algal genera, Laurencia, Chondrophycus and Osmundea (Rhodomelaceae) that are often called the Laurencia complex or Laurencia sensu lato, mainly of the north-western Pacific species, was carried out based on rbcL gene sequences. The sequence data downloaded from GenBank were also included in our analysis. The monophyly of the clade of Osmundea species was supported by high bootstrap value. All examined species of Laurencia sensu stricto with typical features (four periaxial cells per vegetative axial segment, longitudinally oriented secondary pit-connections between contiguous superficial cortical cells, corps en cerise within superficial cortical and trichoblast cells) also constituted a monophyletic clade with high bootstrap value. On the other hand, Chondrophycus species were divided into two separated clades with relatively high bootstrap values respectively. Furthermore, L. flexilis, which has four periaxial cells per vegetative axial segment but lacks secondary pit-connections between contiguous superficial cortical cells, constituted an independent monophyletic clade with high bootstrap value. These results suggest that only two groups, Osmundea and the typical Laurencia, are monophyletic and Chondrophycus is polyphyletic within the Laurencia complex. The phylogenetic position of L. flexilis, an intermediate species between the typical Laurencia and Chondrophycus, must be clarified to determine the key features to distinguish Chondrophycus and Laurencia sensu stricto. Further investigations based on the other genes are expected

Fusarium phytotoxin trichothecenes have an elicitor-like activity in Arabidopsis thaliana, but the activity differed significantly among their molecular species

金沢大学学際科学実験センター遺伝子研究施設Phytopathogenic fungi such as Fusarium spp. synthesize trichothecene family phytotoxins. Although the type B trichothecene, deoxynivalenol (DON), is thought to be a virulence factor allowing infection of plants by their trichothecene-producing Fusarium spp., little is known about effects of trichothecenes on the defense response in host plants. Therefore, in this article, we investigated these effects of various trichothecenes in Fusarium-susceptible Arabidopsis thaliana. Necrotic lesions were observed in Arabidopsis leaves infiltrated by 1 μM type A trichothecenes such as T-2 toxin. Trichothecene-induced lesions exhibited dead cells, callose deposition, generation of hydrogen peroxide, and accumulation of salicylic acids. Moreover, infiltration by trichothecenes caused rapid and prolonged activation of two mitogen-activated protein kinases and induced expression of both PR-1 and PDF1.2 genes. Thus, type A trichothecenes trigger the cell death by activation of an elicitor-like signaling pathway in Arabidopsis. Although DON did not have such an activity even at 10 μM, translational inhibition by DON was observed at concentrations above 5 μM. These results suggested that DON is capable of inhibiting translation in Arabidopsis cells without induction of the elicitor-like signaling pathway. © 2006 The American Phytopathological Society.

Biochemical classification of tauopathies by immunoblot, protein sequence and mass spectrometric analyses of sarkosyl-insoluble and trypsin-resistant tau

Intracellular filamentous tau pathology is the defining feature of tauopathies, which form a subset of neurodegenerative diseases. We have analyzed pathological tau in Alzheimer’s disease, and in frontotemporal lobar degeneration associated with tauopathy to include cases with Pick bodies, corticobasal degeneration, progressive supranuclear palsy, and ones due to intronic mutations in MAPT. We found that the C-terminal band pattern of the pathological tau species is distinct for each disease. Immunoblot analysis of trypsin-resistant tau indicated that the different band patterns of the 7–18 kDa fragments in these diseases likely reflect different conformations of tau molecular species. Protein sequence and mass spectrometric analyses revealed the carboxyl-terminal region (residues 243–406) of tau comprises the protease-resistant core units of the tau aggregates, and the sequence lengths and precise regions involved are different among the diseases. These unique assembled tau cores may be used to classify and diagnose disease strains. Based on these results, we propose a new clinicopathological classification of tauopathies based on the biochemical properties of tau

JNK pathway plays a critical role for expansion of human colorectal cancer in the context of BRG1 suppression

Tumor stem cells (TSCs), capable of self-renewal and continuous production of progeny cells, could be potential therapeutic targets. We have recently reported that chromatin remodeling regulator Brg1 is required for maintenance of murine intestinal TSCs and stemness feature of human colorectal cancer (CRC) cells by inhibiting apoptosis. However, it is still unclear how BRG1 suppression changes the underlying intracellular mechanisms of human CRC cells. We found that Brg1 suppression resulted in upregulation of the JNK signaling pathway in human CRC cells and murine intestinal TSCs. Simultaneous suppression of BRG1 and the JNK pathway, either by pharmacological inhibition or silencing of c-JUN, resulted in even stronger inhibition of the expansion of human CRC cells compared to Brg1 suppression alone. Consistently, high c-JUN expression correlated with worse prognosis for survival in human CRC patients with low BRG1 expression. Therefore, the JNK pathway plays a critical role for expansion and stemness of human CRC cells in the context of BRG1 suppression, and thus a combined blockade of BRG1 and the JNK pathway could be a novel therapeutic approach against human CRC

DNA polymerases ν and θ are required for efficient immunoglobulin V gene diversification in chicken

Polν and Polθ have specialized functions in immunoglobulin gene rearrangements and only contribute to DNA repair when other homologous recombination–related DNA polymerases are absent