Modulation of Lipid Kinase PI4KIIα Activity and Lipid Raft Association of Presenilin 1 Underlies γ-Secretase Inhibition by Ginsenoside (20S)-Rg3

Amyloid β-peptide (Aβ) pathology is an invariant feature of Alzheimer disease, preceding any detectable clinical symptoms by more than a decade. To this end, we seek to identify agents that can reduce Aβ levels in the brain via novel mechanisms. We found that (20S)-Rg3, a triterpene natural compound known as ginsenoside, reduced Aβ levels in cultured primary neurons and in the brains of a mouse model of Alzheimer disease. The (20S)-Rg3 treatment induced a decrease in the association of presenilin 1 (PS1) fragments with lipid rafts where catalytic components of the γ-secretase complex are enriched. The Aβ-lowering activity of (20S)-Rg3 directly correlated with increased activity of phosphatidylinositol 4-kinase IIα (PI4KIIα), a lipid kinase that mediates the rate-limiting step in phosphatidylinositol 4,5-bisphosphate synthesis. PI4KIIα overexpression recapitulated the effects of (20S)-Rg3, whereas reduced expression of PI4KIIα abolished the Aβ-reducing activity of (20S)-Rg3 in neurons. Our results substantiate an important role for PI4KIIα and phosphoinositide modulation in γ-secretase activity and Aβ biogenesis.     

β-Catenin-Driven Binary Fate Specification Segregates Germ Layers in Ascidian Embryos

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Highlights? β-catenin nuclear asymmetry after animal-vegetal-oriented cell divisions ? β-catenin nuclear asymmetry drives binary cell fate choices ? Combinatorial codes of nuclear β-catenin activation segregate ascidian germ layers ? Nuclear β-catenin ON-to-OFF activity is required for marginal mesoderm formation     

Lipoplex size determines lipofection efficiency with or without serum

In order to identify factors affecting cationic Iiposome-mediated gene transfer, the relationships were examined among cationic liposome/DNA complex (lipoplex)-cell interactions, lipoplex size and lipoplex-mediated transfection (lipofection) efficiency. It was found that lipofection efficiency was determined mainly by lipoplex size, but not by the extent of lipoplex-cell interactions including binding, uptake or fusion. In addition, it was found that serum affected mainly lipoplex size, but not lipoplex-cell interactions, which effect was the major reason behind the inhibitory effect of serum on lipofection efficiency. It was concluded that, in the presence or absence of serum, lipoplex size is a major factor determining Iipofection efficiency. Moreover, in the presence or absence of serum, lipoplex size was found to affect lipofection efficiency by controlling the size of the intracellular vesicles containing lipoplexes after internalization, but not by affecting lipoplex-cell interactions. In addition, large lipoplex particles showed, in general, higher lipofection efficiency than small particles. These results imply that, by controlling lipoplex size, an efficient lipid delivery system may be achieved for in vitro and in vivo gene therapy.     

Chemical Synthesis and Characterization of α-N-Octanoyl and Other α-N-Acyl Colistin Nonapeptide Derivatives

Eight α-N-acyl colistin nonapeptide derivatives including three aliphatic, four aromatic and one alicyclic derivatives were synthesized by the reaction of colistin nonapeptide with corresponding acid chlorides. This acylation reaction was carried out under the condition kept restrictedly at pH 5,0 in order to introduce an acyl group only to α-amino group but not to γ-amino group existing in a colistin nonapeptide molecule. Synthetic method and several physico-chemical natures of these acyl colistin nonapeptide derivatives are given in this paper.

All of the acylated derivatives thus synthesized exhibited characteristic antimicrobial activities. Antimicrobial spectra were substantially based upon a gram-negative type and not so much altered by chemical structures of acyl groups which were considerably differentiated from each other such as cyclic or chain form. Thus, more possible response of carbon size than its structure to the antimicrobial effectiveness was inferred. In spite of almost no toxicity and feeble antimicrobial activity of colistin nonapeptide itself, these acylated colistin nonapeptide derivatives showed a toxicity against mice at a dose of 16.9~70 mg/kg in LD₅₀, which, however, was inferior to the toxicity of colistin sulfate, possibly correspondent to their much weaker antimicrobial activities, as a whole. Hence, it seems likely that acyl part of these acylated colistin nonapeptide derivatives including that of colistin is seriously responsible for the biological activities.     

Carbon cycling and sequestration in a Japanese red pine (Pinus densiflora) forest on lava flow of Mt. Fuji

Biometric-based carbon flux measurements were conducted in a pine forest on lava flow of Mt. Fuji, Japan, in order to estimate carbon cycling and sequestration. The forest consists mainly of Japanese red pine (Pinus densiflora) in a canopy layer and Japanese holly (Ilex pedunculosa) in a subtree layer. The lava remains exposed on the ground surface, and the soil on the lava flow is still immature with no mineral soil layer. The results showed that the net primary production (NPP) of the forest was 7.3 ± 0.7 t C ha^?1 year^?1, of which 1.4 ± 0.4 t C ha^?1 year^?1 was partitioned to biomass increment, 3.2 ± 0.5 t C ha^?1 year^?1 to above-ground fine litter production, 1.9 t C ha^?1 year^?1 to fine root production, and 0.8 ± 0.2 t C ha^?1 year^?1 to coarse woody debris. The total amount of annual soil surface CO₂ efflux was estimated as 6.1 ± 2.9 t C ha^?1 year^?1, using a closed chamber method. The estimated decomposition rate of soil organic matter, which subtracted annual root respiration from soil respiration, was 4.2 ± 3.1 t C ha^?1 year^?1. Biometric-based net ecosystem production (NEP) in the pine forest was estimated at 2.9 ± 3.2 t C ha^?1 year^?1, with high uncertainty due mainly to the model estimation error of annual soil respiration and root respiration. The sequestered carbon being allocated in roughly equal amounts to living biomass (1.4 t C ha^?1 year^?1) and the non-living C pool (1.5 t C ha^?1 year^?1). Our estimate of biometric-based NEP was 25 % lower than the eddy covariance-based NEP in this pine forest, due partly to the underestimation of NPP and difficulty of estimation of soil and root respiration in the pine forest on lava flows that have large heterogeneity of soil depth. However, our results indicate that the mature pine forest acted as a significant carbon sink even when established on lava flow with low nutrient content in immature soils, and that sequestration strength, both in biomass and in soil organic matter, is large.     

Isolation,Structure and Physiological Activities of Piericidin B,Natural Insecticide Produced by a Streptomyces

Piericidin B was isolated from mycellia of Streptomyces mobaraensis besides piericidin A. On the basis of IR, NMR and mass spectral studies together with chemical evidences, its structure was assigned as Id. Its physiological activities are also deescribd.     

Method for Enrichment of Rhodopseudomonas sphaeroides from Fresh Water

An inulinase was highly purified from the culture broth of Penicillium purpurogenum by chromatographies on DEAE-Sepharose CL-6B, Toyopearl HW-65, and Bio-Gel P-100. The enzyme was homogeneous by disc electrophoretic analysis. The molecular weight was 6.4 × 10⁴ by SDS-disc electrophoresis and gel filtration on Bio-Gel P-150. The isoelectric point was pH 3.6 by isoelectric focusing. The enzyme hydrolyzed inulin rapidly, but did not affect sucrose. By paper chromatography analysis, the major products from inulin were tri-, tetra-, penta-, and hexa-saccharides. The substrate specificity of the enzyme on hydrolyses of fructo-oligosaccharides[1^F(1-β-d-fructofuranosyl)n sucrose (n = 1 to 6 and n (average of polymerization degree) = 8)] were examined. The Km values and relative maximum velocities for the hydrolyses of inulin and fructo-oligosaccharides (GF_n, n = 2 to 7 and n = 9) were as follows: inulin, (DP = 35) 0.21 mM and 100; GF₉, 0.24 mM and 86.5; GF₇, 0.33 mM and 132; GF₆, 0.85 mM and 71.2; GF₅, 3.8 mM and 25.4; GF₄, 2.8 mM and 28.8; GF₃, (nystose) 16 mM and 0.8; GF₂ (1-kestose), 8.4 mM and 0.2. The molecular activities for the hydrolyses of fructo-oligosaccharides (GF_n, n = 2 to 6) were increased depending on the degree of polymerization of fructosyl residues, and were nearly constant if the polymerization degree was over seven. These results strongly suggested that the endo-type inulinase from Penicillium purpurogenum had a subsite structure consisting of at least seven subsites.     

Consolidation of Soybean Protein Coagulate

The process of dehydration of soybean protein coagulate in expression involves two mechanisms, filtration and consolidation. The filtration process was explained by Ruth’s filtration model. The consolidation process, except for secondary consolidation, was analyzed by the modified consolidation model of Shirato et al., taking into account the compressibility of cake. The modified coefficient of consolidation was not affected significantly by the pressure applied. Evaluation of the modified coefficient of consolidation is of importance for an attempt to improve the current production of soybean protein.