Ketone bodies: A double-edged sword for mammalian life span

Accumulating evidence suggests health benefits of ketone bodies, and especially for longevity. However, the precise role of endogenous ketogenesis in mammalian life span, and the safety and efficacy of the long-term exogenous supplementation of ketone bodies remain unclear. In the present study, we show that a deficiency in endogenous ketogenesis, induced by whole-body Hmgcs2 deletion, shortens life span in mice, and that this is prevented by daily ketone body supplementation using a diet containing 1,3-butanediol, a precursor of β-hydroxybutyrate. Furthermore, feeding the 1,3-butanediol-containing diet from early in life increases midlife mortality in normal mice, but in aged mice it extends life span and prevents the high mortality associated with atherosclerosis in ApoE-deficient mice. By contrast, an ad libitum low-carbohydrate ketogenic diet markedly increases mortality. In conclusion, endogenous ketogenesis affects mammalian survival, and ketone body supplementation may represent a double-edged sword with respect to survival, depending on the method of administration and health status.     

Metabolomics‐based systematic prediction of yeast lifespan and its application for semi‐rational screening of ageing‐related mutants

Metabolomics – the comprehensive analysis of metabolites – was recently used to classify yeast mutants with no overt phenotype using raw data as metabolic fingerprints or footprints. In this study, we demonstrate the estimation of a complicated phenotype, longevity, and semi‐rational screening for relevant mutants using metabolic profiles as strain‐specific fingerprints. The fingerprints used in our experiments are profiled data consisting of individually identified and quantified metabolites rather than raw spectrum data. We chose yeast replicative lifespan as a model phenotype. Several yeast mutants that affect lifespan were selected for analysis, and they were subjected to metabolic profiling using mass spectrometry. Fingerprinting based on the profiles revealed a correlation between lifespan and metabolic profile. Amino acids and nucleotide derivatives were the main contributors to this correlation. Furthermore, we established a multivariate model to predict lifespan from a metabolic profile. The model facilitated the identification of putative longevity mutants. This work represents a novel approach to evaluate and screen complicated and quantitative phenotype by means of metabolomics.     

Solid-phase synthesis of 5'-phosphorylated oligodeoxynucleotides

We used morpholino groups to protect phosphate during the phosphorylation of the 5'-terminal ends of oligodeoxynucleotides, via phosphotriester and phosphoramidite intermediates. These groups could be removed selectively.     

High-efficiency bioaffinity separation of cells and proteins using novel thermoresponsive biotinylated magnetic nanoparticles

Thermoresponsive magnetic nanoparticles with an upper critical solution temperature (UCST) in aqueous solution were synthesized for the first time. Named Therma-Max, the material was synthesized by redox copolymerization of N-acryloyl glycinamide with a monomer form of biotin using methacrylated dextran-magnetite. While the resulting Therma-Max was completely dispersed at temperatures above the UCST (18°C) and could not be separated by a permanent magnet, it was rapidly flocculated when the temperature fell below the UCST and was easily separated by a permanent magnet. The flocculated particles dispersed completely when the temperature was raised to above the UCST. Because biotin was immobilized on the Therma-Max, avidin and antibodies were subsequently immobilized with good efficiency. Furthermore, transiently transfected Arabidopsis protoplasts, which have surface display of CD4 antigen, were efficiently captured and enriched by using a biotinylated anti-CD4 antibody in combination with avidin-conjugated Therma-Max. Also, the silkworm storage protein (SP2) was efficiently separated from the silkworm hemolymph by using biotinylated anti-IgG antibody and anti-SP2 antibody in combination with avidin-conjugated Therma-Max. In both cases, it was confirmed that specificity and adsorption capacity were markedly improved by converting the conventional micro-size fine magnetic particles to nano-size particles. These results show the potential of Therma-Max with a UCST in bioaffinity separation of cells and biomolecules.     

Nonradioactive labeling with chemically modified cytosine tails by the polymerase chain reaction.

We developed a modified nonradioactive method for the detection of DNA. This method makes use of the polymerase chain reaction for preparation of probes; that is, a DNA fragment inserted in the polylinker region of an M13 or pUC vector is amplified with primers that have a modified cytosine tail at the 5' terminus (C-tailed primers). By this method, large amounts of labeled probes can be obtained easily. After hybridization, modified cytosine tails can be detected immunologically. DNA labeled by this method could be used in plaque hybridization. We could detect 0.05 pg of dot-blotted labeled DNA in 30 min with an enzyme-catalyzed chemiluminescence reaction.