Relationship Between β-Amyloid and Mitochondrial Dynamics

Mitochondria as dynamic organelles undergo morphological changes through the processes of fission and fusion which are major factors regulating their functions. A disruption in the balance of mitochondrial dynamics induces functional disorders in mitochondria such as failed energy production and the generation of reactive oxygen species, which are closely related to pathophysiological changes associated with Alzheimer’s disease (AD). Recent studies have demonstrated a relationship between abnormalities in mitochondrial dynamics and impaired mitochondrial function, clarifying the effects of morphofunctional aberrations which promote neuronal cell death in AD. Several possible signaling pathways have been suggested for a better understanding of the mechanism behind the key molecules regulating mitochondrial morphologies. However, the exact machinery involved in mitochondrial dynamics still has yet to be elucidated. This paper reviews the current knowledge on signaling mechanisms involved in mitochondrial dynamics and the significance of mitochondrial dynamics in controlling associated functions in neurodegenerative diseases, particularly in AD.     

Feasibility of hydrogen production from ripened fruits by a combined two-stage (dark/dark) fermentation system

Anaerobic fermentation for hydrogen (H₂) production was studied in a two-stage fermentation system fed with different ripened fruit feedstocks (apple, pear, and grape). Among the feedstocks, ripened apple was the most efficient substrate for cumulative H₂ production (4463.7 mL-H₂ L⁻¹-culture) with a maximum H₂ yield (2.2 mol H₂ mol⁻¹ glucose) in the first stage at a hydraulic retention time (HRT) of 18 h. The additional cumulative biohydrogen (3337.4 mL-H₂ L⁻¹-culture) was produced in the second stage with the reused residual substrate from the first stage. The major byproducts in this study were butyrate, acetate, and ethanol, and butyrate was dominant among them in all test runs. During the two-stage system, the energy efficiency (H₂ conversion) obtained from mixed ripened fruits (RF) increased from 4.6% (in the first stage) to 15.5% (in the second stage), which indicated the energy efficiency can be improved by combined hydrogen production process. The RF could be used as substrates for biohydrogen fermentation in a two-stage (dark/dark) fermentation system.     

RML1 and RML2, Arabidopsis genes required for cell proliferation at the root tip.

New cells are produced from the meristematic tissues located at the shoot and root tip throughout the life of higher plants. To investigate the genetic mechanism regulating meristematic activity, we isolated and characterized four single-gene, recessive mutants in Arabidopsis thaliana called root meristemless (rml). Complementation tests identified two RML loci; RML1 maps to chromosome IV and RML2 maps to chromosome III. These mutants produce normal embryonic roots that either did not undergo or experienced limited cell division following germination, resulting in primary roots of less than 2.0 mm in length. Mutants can produce lateral and adventitious roots, which can grow to a length comparable to the embryonic root and arrest, indicating that the growth arrest is unrelated to the embryonic dormancy process. Neither the addition of growth regulators to the media nor the removal of shoots can rescue mutant roots from growth arrest, indicating that the mutant phenotype is not caused by a shortage of known growth regulators or by a transmissible shoot inhibitor. Normal cell division ability in mutant embryo, shoot, and callus cells indicates that the RML gene functions are not part of the general cell division processes; rather, they are involved specifically in activating the cell division cycle in the root apical cells.     

Fabrication of degradable carboxymethyl cellulose (CMC) microneedle with laser writing and replica molding process for enhancement of transdermal drug delivery

Transdermal drug delivery system (TDDS) may provide a more reliable method of drug delivery than oral delivery by avoiding gut absorption and first-pass metabolism, but needs a method for efficiently crossing the epidermal barrier. To enhance the delivery through the skin, we have developed a biocompatible, dissolvable microneedle array made from carboxymethyl cellulose (CMC). Using laser ablation for creating the mold greatly improved the efficiency and reduced the cost of microneedle fabrication. Mixing CMC with amylopectin (AP) enhanced the mechanical and tunable dissolution properties of the microneedle for controlled release of model compounds. Using the CMC microneedle array, we observed significant enhancement in the skin permeability of a fluorescent model compound, and also increase in the anti-oxidant activity of ascorbic acid after crossing the skin. Our dissolvable microneedle array provides a new and biocompatible method for delivery of drugs and cosmetic compounds through the skin.     

Molecular basis of the differences between normal and tumor tissues of gastric cancer

To be able to describe the differences between the normal and tumor tissues of gastric cancer at a molecular level would be essential in the study of the disease. We investigated the gene expression pattern in the two types of tissues from gastric cancer by performing expression profiling of 86 tissues on 17K complementary DNA microarrays. To select for the differentially expressed genes, class prediction algorithm was employed. For predictor selection, samples were first divided into a training (n=58), and a test set (n=28). A group of 894 genes was selected by a t-test in a training set, which was used for cross-validation in the training set and class (normal or tumor) prediction in the test set. Smaller groups of 894 genes were individually tested for their ability to correctly predict the normal or tumor samples based on gene expression pattern. The expression ratios of the 5 genes chosen from microarray data can be validated by real time RT-PCR over 6 tissue samples, resulting in a high level of correlation, individually or combined. When a representative predictor set of 92 genes was examined, pathways of 'focal adhesion' (with gene components of THBS2, PDGFD, MAPK1, COL1A2, COL6A3), 'ECM-receptor interaction' pathway (THBS2, COL1A2, COL6A3, FN1) and 'TGF-beta signaling' (THBS2, MAPK1, INHBA) represent some of the main differences between normal and tumor of gastric cancer at a molecular level.     

MCPIP1 ribonuclease antagonizes dicer and terminates microRNA biogenesis through precursor microRNA degradation

MicroRNAs (miRNAs) are versatile regulators of gene expression and undergo complex maturation processes. However, the mechanism(s) stabilizing or reducing these small RNAs remains poorly understood. Here we identify mammalian immune regulator MCPIP1 (Zc3h12a) ribonuclease as a broad suppressor of miRNA activity and biogenesis, which counteracts Dicer, a central ribonuclease in miRNA processing. MCPIP1 suppresses miRNA biosynthesis via cleavage of the terminal loops of precursor miRNAs (pre-miRNAs). MCPIP1 also carries a vertebrate-specific oligomerization domain important for pre-miRNA recognition, indicating its recent evolution. Furthermore, we observed potential antagonism between MCPIP1 and Dicer function in human cancer and found a regulatory role of MCPIP1 in the signaling axis comprising miR-155 and its target c-Maf. These results collectively suggest that the balance between processing and destroying ribonucleases modulates miRNA biogenesis and potentially affects pathological miRNA dysregulation. The presence of this abortive processing machinery and diversity of MCPIP1-related genes may imply a dynamic evolutional transition of the RNA silencing system.     

Structural and functional studies of the Mycobacterium tuberculosis VapBC30 toxin-antitoxin system: implications for the design of novel antimicrobial peptides

Toxin-antitoxin (TA) systems play important roles in bacterial physiology, such as multidrug tolerance, biofilm formation, and arrest of cellular growth under stress conditions. To develop novel antimicrobial agents against tuberculosis, we focused on VapBC systems, which encompass more than half of TA systems in Mycobacterium tuberculosis. Here, we report that theMycobacterium tuberculosis VapC30 toxin regulates cellular growth through both magnesium and manganese ion-dependent ribonuclease activity and is inhibited by the cognate VapB30 antitoxin. We also determined the 2.7-Å resolution crystal structure of the M. tuberculosis VapBC30 complex, which revealed a novel process of inactivation of the VapC30 toxin via swapped blocking by the VapB30 antitoxin. Our study on M. tuberculosis VapBC30 leads us to design two kinds of VapB30 and VapC30-based novel peptides which successfully disrupt the toxin-antitoxin complex and thus activate the ribonuclease activity of the VapC30 toxin. Our discovery herein possibly paves the way to treat tuberculosis for next generation.     

Application of free-flow electrophoresis/2-dimentional gel electrophoresis for fractionation and characterization of native proteome of Pseudomonas putida KT2440

Free Flow Electrophoresis (FFE) is a liquid-based isoelectric focusing method. Unlike conventional in-gel fractionation of proteins, FFE can resolve proteins in their native forms and fractionation of subcellular compartments of the cell is also possible. To test the efficacy of the FFE method, the native cytosol proteome of a bacterium, Pseudomonas putida KT2440 was fractionated by FFE and the spectrum of protein elutes was characterized in association with 2-dimentional gel electrophoresis (2-DE). Major native proteins of P. putida KT2440 were eluted in the range of pH 4.8 approximately 6.0 in FFE, whereas the denatured proteome of P. putida KT2440 was widely distributed in the rage of pH 4 approximately 10 in the 2-DE analysis. In addition, one of the three FFE major fractions, which was eluted at pH 5.0, was further analyzed using 2-DE/MS-MS. Then, the pH range of identified proteins eluted in 2-DE/MS-MS was 4.72 approximately 5.89, indicating that observed pi values of native cytosolic proteomes in FFE were narrower than those of denatured cytosolic proteome. These results suggest that FFE fractionation and 2-DE/MS analysis may be useful tools for characterization of native proteomes of P. putida KT2440 and comparative analysis between denatured and native proteomes.     

Evaluation of characteristic aroma compounds of Citrus natsudaidai Hayata (Natsudaidai) cold-pressed peel oil

The characteristic aroma compounds of Citrus natsudaidai Hayata essential oil were evaluated by a combination of instrumental and sensory methods. Sixty compounds were identified and quantified, accounting for 94.08% of the total peel oil constituents. Limonene was the most abundant compound (80.68%), followed by gamma-terpinene (5.30%), myrcene (2.25%) and alpha-pinene (1.30%). Nineteen compounds which could not be identified in the original oil were identified in the oxygenated fraction. Myrcene, linalool, alpha-pinene, beta-pinene, limonene, nonanal, gamma-terpinene, germacrene D, and perillyl alcohol were the active aroma components (FD-factor > 3(6)), whereas beta-copaene, cis-sabinene hydrate and 1-octanol were suggested as characteristic aroma compounds, having a Natsudaidai-like aroma in the GC effluent. Three other compounds, heptyl acetate, (E)-limonene oxide and 2,3-butanediol, which each showed a high RFA value (>35) were considered to be important in the reconstruction of the original Natsudaidai oil from pure odor chemicals. The results indicate that 1-octanol was the aroma impact compound of C. natsudaidai Hayata peel oil.     

Draft Genome Sequence of Fusobacterium nucleatum subsp. fusiforme ATCC 51190T

Fusobacterium nucleatum, one of the major causative bacteria of periodontitis, is classified into five subspecies (nucleatum, polymorphum, vincentii, animalis, and fusiforme) on the basis of the several phenotypic characteristics and DNA homology. This is the first report of the draft genome sequence of F. nucleatum subsp. fusiforme ATCC 51190(T).