A simple synthesis of four stereoisomers of roseoside and their inhibitory activity on leukotriene release from mice bone marrow-derived cultured mast cells

Four stereoisomers of roseoside (vomifoliol glucosides) were synthesized using glucose as a chiral resolving reagent. The four synthetic stereoisomers exhibited inhibitory activity on leukotriene release from mouse bone marrow-derived cultured mast cells (BMCMC). The (6S)-isomers of roseoside were about twice as active as (6R)-isomers.     

Three-dimensional colocalization analysis of plasma-derived apolipoprotein B with amyloid plaques in APP/PS1 transgenic mice

Parenchymal accumulation of amyloid-beta (Aβ) is a hallmark pathological feature of Alzheimer’s disease. An emerging hypothesis is that blood-to-brain delivery of Aβ may increase with compromised blood–brain barrier integrity. In plasma, substantial Aβ is associated with triglyceride-rich lipoproteins (TRLs) secreted by the liver and intestine. Utilizing apolipoprotein B as an exclusive marker of hepatic and intestinal TRLs, here we show utilizing an highly sensitive 3-dimensional immuno-microscopy imaging technique, that in APP/PS1 amyloid transgenic mice, concomitant with substantially increased plasma Aβ, there is a significant colocalization of apolipoprotein B with cerebral amyloid plaque. The findings are consistent with the possibility that circulating lipoprotein-Aβ contributes to cerebral amyloidosis.     

High Rate of N2 Fixation by East Siberian Cryophilic Soil Bacteria as Determined by Measuring Acetylene Reduction in Nitrogen-Poor Medium Solidified with Gellan Gum

For evaluating N₂ fixation of diazotrophic bacteria, nitrogen-poor liquid media supplemented with at least 0.5% sugar and 0.2% agar are widely used for acetylene reduction assays. In such a soft gel medium, however, many N₂-fixing soil bacteria generally show only trace acetylene reduction activity. Here, we report that use of a N₂ fixation medium solidified with gellan gum instead of agar promoted growth of some gellan-preferring soil bacteria. In a soft gel medium solidified with 0.3% gellan gum under appropriate culture conditions, bacterial microbiota from boreal forest bed soils and some free-living N₂-fixing soil bacteria isolated from the microbiota exhibited 10- to 200-fold-higher acetylene reduction than those cultured in 0.2% agar medium. To determine the N₂ fixation-activating mechanism of gellan gum medium, qualitative differences in the colony-forming bacterial components from tested soil microbiota were investigated in plate cultures solidified with either agar or gellan gum for use with modified Winogradsky''s medium. On 1.5% agar plates, apparently cryophilic bacterial microbiota showed strictly distinguishable microbiota according to the depth of soil in samples from an eastern Siberian Taiga forest bed. Some pure cultures of proteobacteria, such as Pseudomonas fluorescens and Burkholderia xenovorans, showed remarkable acetylene reduction. On plates solidified with 1.0% gellan gum, some soil bacteria, including Luteibacter sp., Janthinobacterium sp., Paenibacillus sp., and Arthrobacter sp., uniquely grew that had not grown in the presence of the same inoculants on agar plates. In contrast, Pseudomonas spp. and Burkholderia spp. were apparent only as minor colonies on the gellan gum plates. Moreover, only gellan gum plates allowed some bacteria, particularly those isolated from the shallow organic soil layer, to actively swarm. In consequence, gellan gum is a useful gel matrix to bring out growth potential capabilities of many soil diazotrophs and their consortia in communities of soil bacteria.In 1967, Schöllhorn and Burris discovered that nitrogenase from an N₂-fixing rhizobium of soybean can reduce acetylene to produce ethylene (C₂H₄) (32), a reaction analogous to the conversion of the natural substrate N₂ into ammonia. Shortly afterwards, it was shown that this acetylene reduction activity parallels N₂ reduction by nitrogenase (13), and since then, acetylene reduction assays have been widely used in the evaluation of biological N₂ fixation. An acetylene reduction assay is generally performed under the following conditions: precultured bacterial cells are suspended into N-free or -deficient liquid medium containing a carbon source, usually d-glucose or d-mannitol (35) at 0.5 to 2.0%, and exposed for 24 h or less at a representative room temperature, e.g., 25°C (2). However, this method is not applicable to free-living, microaerobic N₂-fixing bacteria, which have been regarded as notoriously difficult to culture. To solve this problem, Döbereiner and her group developed a soft gel method (7), which used 0.2% agar as a gel matrix for the medium. Due to a vertical gradient of dissolved oxygen concentrations, these microaerobes formed a thin layer at the particular depth of the medium that contained an ideal level of dissolved oxygen (10). Also, significant activities in acetylene reduction assays were observed for N₂-fixing microaerobes, particularly those from the rhizoplane of monocotyledonous crop plants (e.g., Azospirillum and Herbaspirillum spp.) (1, 9, 40). To date, these soft gel media solidified with 0.2% agar have been widely used as the most basic method for the screening of free-living or difficult-to-culture N₂-fixing bacteria (2, 16).In an agar composed of soft gel, however, the layer formation of highly transparent colony-forming bacteria is often obscured and is more difficult to observe than comparable layer formation in water due to the higher turbidity of the agar gel, and some members of the soil bacterial community do not show any positive response in acetylene reduction assays under these conditions. These drawbacks to the usage of agar as a soft gel matrix delayed the recognition that free-living N₂ fixers make a potent contribution to the support of ecosystems under adverse soil conditions. Hashidoko et al. developed an improved soft gel medium for growth of N₂-fixing bacteria in 2002 (15). In their study, 0.2% agar was replaced with 0.3% gellan gum, a bacterial extracellular polysaccharide (EPS) produced by Sphingomonas elodea (a synonym of Sphingomonas paucimobilis) ATCC 31461 (12, 17, 18). Initially, gellan gum was used for the purpose of preparing a highly transparent soft gel medium that was better for culturing microaerobic N₂-fixing rhizobacteria. It had other favorable physical properties: when 0.3% gellan gum containing Winogradsky''s mineral mixture was autoclaved, the medium remained in a liquid form over a period of several hours while cooling to room temperature. Even after the gellan gum had been solidified, the soft gel was easily liquefied upon mechanical agitation. The liquefied medium was able to resolidify after a short period of time, so it was easy to uniformly disperse inoculants into the soft gel medium. The outstanding transparency (14) and other properties of this gel matrix enable easy visualization of transparent colony-forming N₂-fixing bacteria and also allow observation of their responses to various concentrations of dissolved oxygen and cell motilities (15).In many preliminary experiments, nitrogen-poor gellan gum media allowed high growth of diazotrophs, but this study was needed to compare gellan gum with agar as a gel matrix for N₂ fixation. Because Siberian boreal forest soils have been noted for their low N₂-fixing capability (3), we first cultured bacterial microbiota from the eastern Siberian Taiga forest bed in gellan gum medium. A quantitative comparison of N₂ fixation behaviors of free-living soil bacteria was attempted to investigate gellan gum as a potential N₂ fixation-promoting soft gel matrix. We here first report on the efficacy of gellan gum as a soft gel matrix for monitoring acetylene reduction by the use of free-living N₂-fixing soil bacteria.     

Biochemical and immunohistochemical analyses of GnRH-like peptides in the nerve ganglion of the chiton, Acanthopleura japonica

We examined whether a gonadotropin-releasing hormone (GnRH)-like peptide is present in the nerve ganglion of the chiton Acanthopleura japonica (Mollusca, Polyplacophora) using reverse-phase high performance liquid chromatography (rpHPLC) combined with time-resolved fluoroimmunoas-say (TR-FIA) analysis, and immunohistochemistry. An extract of the chiton head region showed a similar retention time to that of synthetic lamprey GnRH-II on rpHPLC combined with TR-FIA analysis using a rabbit polyclonal antibody raised against chicken GnRH-II (aCII6). Cell bodies immunostained with LRH13 (a mouse monoclonal antibody raised against the common amino acid sequence of vertebrate GnRH) were detected in the cerebrobuccal ring (CBR). Cell bodies immunostained with aCII6 were not only observed in the CBR but also in the lateral nerve cord (LCo). Fibers immunostained with LRH13 and aCII6 were widely distributed throughout the central nervous system in the CBR, subradular ganglion (SubRG), pedal nerve cord (PCo), pedal commissure (P/PCom), lateropedal commissure (L/PCom), and from the LCo to the suprarectal commissure (SupRecCom). The cell bodies and fibers immunostained with these two antisera were distinguishable by dual-label immunohistochemistry. These results suggest that multiple GnRH-like peptides are present in the nerve ganglion of the chiton Acanthopleura japonica.     

Osmoregulation of fission yeast: cloning of two distinct genes encoding glycerol-3-phosphate dehydrogenase, one of which is responsible for osmotolerance for growth

Many types of microorganisms, including both prokaryotes and eukaryotes, have developed mechanisms to adapt to severe osmotic stress. In this study, we isolated multicopy suppressor genes for a Schizosaccharomyces pombe mutant, which exhibited the clear phenotype of being osmosensitive for growth (Osm^s) on agar plates containing high concentrations of either non-ionic or ionic osmotic solutes. Two genes were thus identified, and each was suggested to encode an NADH-dependent glycerol-3-phosphate dehydrogenase (GPD), which is required for glycerol synthesis. The nucleotide sequences, determined for these genes (named gpd1 ⁺ and gpd2 ⁺, respectively), revealed that S. pombe has two distinct GPD isozymes. They are only 60% identical to each other in their amino acid sequences. One such isozyme, GPD1, was shown to be directly involved in osmoregulation, based on the following observations. (i) Expression of gpd1 ⁺ was regulated at the mRNA level in response to osmotic upshift, (ii) It was demonstrated that wild-type cells markedly accumulated internal glycerol under high-osmolarity growth conditions. (iii) Δ gpd1 mutants, however, failed to do so even in a high-osmolarity medium, and thus exhibited an Osm^s phenotype. On the other hand, the gpd2 ⁺ gene was constitutively expressed at a particular low level, regardless of the osmolarity of the medium.     

OGT Regulates Hematopoietic Stem Cell Maintenance via PINK1-Dependent Mitophagy

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Host-produced ethylene is required for marked cell expansion and endoreduplication in dodder search hyphae

The genus Cuscuta comprises stem holoparasitic plant species with wide geographic distribution. Cuscuta spp. obtain water, nutrients, proteins, and mRNA from their host plants via a parasitic organ called the haustorium. As the haustorium penetrates into the host tissue, search hyphae elongate within the host tissue and finally connect with the host’s vascular system. Invasion by Cuscuta spp. evokes various reactions within the host plant’s tissues. Here, we show that, when Arabidopsis (Arabidopsis thaliana) is invaded by Cuscuta campestris, ethylene biosynthesis by the host plant promotes elongation of the parasite’s search hyphae. The expression of genes encoding 1-aminocylclopropane-1-carboxylic acid (ACC) synthases, ACC SYNTHASE2 (AtACS2) and ACC SYNTHASE6 (AtACS6), was activated in the stem of Arabidopsis plants upon invasion by C. campestris. When the ethylene-deficient Arabidopsis acs octuple mutant was invaded by C. campestris, cell elongation and endoreduplication of the search hyphae were significantly reduced, and the inhibition of search hyphae growth was complemented by exogenous application of ACC. In contrast, in the C. campestris-infected Arabidopsis ethylene-insensitive mutant etr1-3, no growth inhibition of search hyphae was observed, indicating that ETHYLENE RESPONSE1-mediated ethylene signaling in the host plant is not essential for parasitism by C. campestris. Overall, our results suggest that C. campestris recognizes host-produced ethylene as a stimulatory signal for successful invasion.

Growth of Cuscuta campestris search hyphae is inhibited in ethylene-deficient Arabidopsis mutants, suggesting that host-derived ethylene acts as a stimulatory signal for parasitism by Cuscuta spp.     

The fragility of a structurally diverse duplication block triggers recurrent genomic amplification

The human genome contains hundreds of large, structurally diverse blocks that are insufficiently represented in the reference genome and are thus not amenable to genomic analyses. Structural diversity in the human population suggests that these blocks are unstable in the germline; however, whether or not these blocks are also unstable in the cancer genome remains elusive. Here we report that the 500 kb block called KRTAP_region_1 (KRTAP-1) on 17q12–21 recurrently demarcates the amplicon of the ERBB2 (HER2) oncogene in breast tumors. KRTAP-1 carries numerous tandemly-duplicated segments that exhibit diversity within the human population. We evaluated the fragility of the block by cytogenetically measuring the distances between the flanking regions and found that spontaneous distance outliers (i.e DNA breaks) appear more frequently at KRTAP-1 than at the representative common fragile site (CFS) FRA16D. Unlike CFSs, KRTAP-1 is not sensitive to aphidicolin. The exonuclease activity of DNA repair protein Mre11 protects KRTAP-1 from breaks, whereas CtIP does not. Breaks at KRTAP-1 lead to the palindromic duplication of the ERBB2 locus and trigger Breakage-Fusion-Bridge cycles. Our results indicate that an insufficiently investigated area of the human genome is fragile and could play a crucial role in cancer genome evolution.     

Designing pheromone communication in swarm robotics: Group foraging behavior mediated by chemical substance

In swarm robotics, communication among the robots is essential. Inspired by biological swarms using pheromones, we propose the use of chemical compounds to realize group foraging behavior in robot swarms. We designed a fully autonomous robot, and then created a swarm using ethanol as the trail pheromone allowing the robots to communicate with one another indirectly via pheromone trails. Our group recruitment and cooperative transport algorithms provide the robots with the required swarm behavior. We conducted both simulations and experiments with real robot swarms, and analyzed the data statistically to investigate any changes caused by pheromone communication in the performance of the swarm in solving foraging recruitment and cooperative transport tasks. The results show that the robots can communicate using pheromone trails, and that the improvement due to pheromone communication may be non-linear, depending on the size of the robot swarm.     

Reconsidering the function of the xyloglucan endotransglucosylase/hydrolase family

Journal of Plant Research - Plants possess an outer cell layer called the cell wall. This matrix comprises various molecules, such as polysaccharides and proteins, and serves a wide array of...