Protective effect of vitamin C against double-strand breaks in reconstituted chromatin visualized by single-molecule observation

Direct attack to genomic DNA by reactive oxygen species causes various types of lesions, including base modifications and strand breaks. The most significant lesion is considered to be an unrepaired double-strand break that can lead to fatal cell damage. We directly observed double-strand breaks of DNA in reconstituted chromatin stained by a fluorescent cyanine dye, YOYO (quinolinium, 1,1'-[1,3- propanediylbis[(dimethyliminio)-3,1- propanediyl]]bis[4-[(3-methyl-2(3H)-benzoxazolylidene)methyl]]-, tetraiodide), in solution, where YOYO is known to have the ability to photo-cleave DNAs by generating reactive oxygen species. Reconstituted chromatin was assembled from large circular DNA (106 kbp) with core histone proteins. We also investigated the effect of vitamin C (ascorbic acid) on preventing photo-induced double-strand breaks in a quantitative manner. We found that DNA is protected against double-strand breaks by the addition of ascorbic acid, and this protective effect is dose dependent. The effective kinetic constant of the breakage reaction in the presence of 5 mM ascorbic acid is 20 times lower than that in the absence of ascorbic acid. This protective effect of ascorbic acid in reconstituted chromatin is discussed in relation to the highly compacted polynucleosomal structure. The results highlight the fact that single-molecule observation is a useful tool for studying double-strand breaks in giant DNA and chromatin.     

Lactic acid bacteria (LAB) bind to human B- or H-antigens expressed on intestinal mucosa

Twenty lactobacilli isolated from human feces were studied for binding to the human blood type B-antigen [Galalpha1-3 (Fucalpha1-2) Gal-] and H-antigen (Fucalpha1-2Gal-] expressed sugar chains in human intestinal mucosa. We found two strains, L. gasseri OLL2755 and L. gasseri OLL2877 that firmly adhere to human B-antigen, and we found L. gasseri OLL2827 bound to the H-antigen.     

Enhanced reactivity of amino-modified oligonucleotides by insertion of aromatic residue

We developed novel amino-modifying reagents, of which an amino group was connected with an aromatic residue by aliphatic linker. It was proved that the insertion of the aromatic residue could increase the reactivity of the amino group on oligonucleotides in comparison with conventional amino-modification.     

Structure basis for antitumor effect of aplyronine a

Aplyronine A, isolated from the sea hare Aplysia kurodai, possesses an exceedingly potent antitumor effect in vivo and it is one of the promising candidates as an anticancer drug. This macrolide is known to depolymerize F-actin and inhibit the polymerization of actin by forming a 1:1 complex with monomeric actin. The first complex structure of actin-aplyronine A was determined via a synchrotron X-ray analysis at a 1.45 A resolution. As expected, aplyronine A binds to a hydrophobic cleft composed of subdomains 1 and 3 of actin by intercalating its aliphatic tail part into the actin molecule as do the other reported F-actin depolymerizing agents. Unexpectedly, this complex structure shows the specific structural features around the trimethylserine moiety, revealed as an important moiety of aplyronine A for cytotoxicity against HeLa cells. Combining this result and our previous one, the moiety should strongly relate to the specific biological activity of aplyronine A; i.e. a potent antitumor effect.     

Complete genome sequence of the dehalorespiring bacterium Desulfitobacterium hafniense Y51 and comparison with Dehalococcoides ethenogenes 195

Desulfitobacterium strains have the ability to dechlorinate halogenated compounds under anaerobic conditions by dehalorespiration. The complete genome of the tetrachloroethene (PCE)-dechlorinating strain Desulfitobacterium hafniense Y51 is a 5,727,534-bp circular chromosome harboring 5,060 predicted protein coding sequences. This genome contains only two reductive dehalogenase genes, a lower number than reported in most other dehalorespiring strains. More than 50 members of the dimethyl sulfoxide reductase superfamily and 30 paralogs of the flavoprotein subunit of the fumarate reductase are encoded as well. A remarkable feature of the genome is the large number of O-demethylase paralogs, which allow utilization of lignin-derived phenyl methyl ethers as electron donors. The large genome reveals a more versatile microorganism that can utilize a larger set of specialized electron donors and acceptors than previously thought. This is in sharp contrast to the PCE-dechlorinating strain Dehalococcoides ethenogenes 195, which has a relatively small genome with a narrow metabolic repertoire. A genomic comparison of these two very different strains allowed us to narrow down the potential candidates implicated in the dechlorination process. Our results provide further impetus to the use of desulfitobacteria as tools for bioremediation.     

Elevated serum monocyte chemoattractant protein-4 and chronic inflammation in overweight subjects

Objective: Chronic inflammation observed in obesity has been reported to be implicated in the development of atherosclerosis. We screened candidate chemokines that link chronic inflammation and obesity. Research Methods and Procedures: Japanese overweight (n = 39, BMI 28.7 ± 0.65 kg/m²) and normal‐weight (n = 24, BMI 22.3 ± 0.45 kg/m²) subjects were enrolled. Using antibody‐based protein microarray, spot intensities of monocyte chemoattractant protein (MCP)‐4, eotaxin, and eotaxin‐2 correlated with anthropometric parameters. We further measured serum concentration of these chemokines and mRNA levels in adipose tissues obtained from volunteers. Results: Serum MCP‐4 levels showed positive correlation with BMI (r = 0.318, p = 0.014), waist (r = 0.316, p = 0.018), and waist‐to‐hip ratio (WHR) (r = 0.264, p = 0.049). Furthermore, MCP‐4 correlated with homeostasis model assessment of insulin resistance (r = 0.392, p = 0.002), high‐sensitivity C‐reactive protein (hsCRP) (r = 0.350, p = 0.006). In step‐wise multiple regression analyses, hsCRP independently correlated with MCP‐4 levels. The expression of MCP‐4 mRNA in visceral adipose tissue positively correlates with BMI. Serum eotaxin levels correlate with BMI (r = 0.262, p = 0.045) and WHR (r = 0.383, p = 0.003). Serum eotaxin‐2 levels correlated with BMI (r = 0.464, p < 0.001), waist (r = 0.333, p = 0.017), and WHR (r = 0.278, p = 0.048). However, eotaxin and eotaxin‐2 levels did not show significant correlation with hsCRP. Discussion: Serum levels of MCP‐4, eotaxin, and eotaxin‐2, which belong to CC chemokine family and share CC chemokine receptor 3, correlated with BMI. These chemokines, especially MCP‐4, may be critical molecules that link obesity and chronic inflammation.