Identification of diacetonamine from soybean curd residue as a sporulation-inducing factor toward Bacillus spp.

Under bioassay-guided investigation, a sporulation-inducing factor (SIF) toward Bacillus spp. was searched for in methanol (MeOH) extracts of soybean curd residues, and diacetonamine (1) was identified as the active compound. SIF was first isolated as a monoacetylated derivative (2, 4.1 mg from 655 g soybean curd residues), and its chemical structure was elucidated by field desorption mass spectrometry, electron ionization mass spectrometry, and nuclear magnetic resonance (NMR) analyses. After 48-h incubation, 40 mu M diacetonamine hydrochloride (1b) exhibited sporulation-inducing activity with 35% sporulation frequency toward a Bacillus amyloliquefaciens wild-type strain (AHU 2170), whereas 40 mu M diacetone acrylamide (3) showed 99% sporulation induction, which was much higher than that of 1b. Although Bacillus megaterium NBRC 15308 was sporulated by the treatment with 400 mu M 1b with 36 and 70% sporulation frequency after 72-and 96-h incubation respectively, 3 at the same concentration showed only 2% sporulation after 72-h incubation. Hence, diacetonamine (1) was characterized as a genuine SIF from soybean curd residues, but it was uncertain whether 1 is a natural product or an artifact. Spores of B. amyloliquefaciens induced by 1b survived after treatment with heating at 95 degrees C for 10 min, also suggesting that 1 is genuine SIF in soybean curd residue. As sporulation induction is likely linked to activation of antibiotic production in some spore-forming Firmicutes bacteria, compound 1 would be a possible chemical tool to develop an effective fermentation technology in Bacillus species

Electronic Structures of N-doped Graphene with Native Point Defects

Nitrogen doping in graphene has important implications in graphene-based devices and catalysts. We have performed the density functional theory calculations to study the electronic structures of N-doped graphene with vacancies and Stone-Wales defect. Our results show that monovacancies in graphene act as hole dopants and that two substitutional N dopants are needed to compensate for the hole introduced by a monovacancy. On the other hand, divacancy does not produce any free carriers. Interestingly, a single N dopant at divacancy acts as an acceptor rather than a donor. The interference between native point defect and N dopant strongly modifies the role of N doping regarding the free carrier production in the bulk pi bands. For some of the defects and N dopant-defect complexes, localized defect pi states are partially occupied. Discussion on the possibility of spin polarization in such cases is given. We also present qualitative arguments on the electronic structures based on the local bond picture. We have analyzed the 1s-related x-ray photoemission and adsorption spectroscopy spectra of N dopants at vacancies and Stone-Wales defect in connection with the experimental ones. We also discuss characteristic scanning tunneling microscope (STM) images originating from the electronic and structural modifications by the N dopant-defect complexes. STM imaging for small negative bias voltage will provide important information about possible active sites for oxygen reduction reaction.Comment: 40 pages, 2 tables, 16 figures. The analysis of Clar sextets is added. This version is published on PHYSICAL REVIEW B 87, 165401(2013

Essential role of caspase-8 in p53/p73-dependent apoptosis induced by etoposide in head and neck carcinoma cells

<p>Abstract</p> <p>Background</p> <p>Caspase-8 is a key upstream mediator in death receptor-mediated apoptosis and also participates in mitochondria-mediated apoptosis via cleavage of proapoptotic Bid. However, the role of caspase-8 in p53- and p73-dependent apoptosis induced by genotoxic drugs remains unclear. We recently reported that the reconstitution of procaspase-8 is sufficient for sensitizing cisplatin- but not etoposide-induced apoptosis, in chemoresistant and caspase-8 deficient HOC313 head and neck squamous cell carcinoma (HNSCC) cells.</p> <p>Results</p> <p>We show that p53/p73-dependent caspase-8 activation is required for sensitizing etoposide-induced apoptosis by utilizing HOC313 cells carrying a temperature-sensitive p53G285K mutant. Restoration of wild-type p53 function under the permissive conditions, together with etoposide treatment, led to substantial transcriptional activation of proapoptotic Noxa and PUMA, but failed to induce apoptosis. In addition to p53 restoration, caspase-8 reconstitution was needed for sensitization to etoposide-induced apoptosis, mitochondria depolarization, and cleavage of the procaspases-3, and -9. In etoposide-sensitive Ca9-22 cells carrying a temperature-insensitive mutant p53, siRNA-based p73 knockdown blocked etoposide-induced apoptosis and procaspase-8 cleavage. However, induction of p73 protein and up-regulation of Noxa and PUMA, although observed in Ca9-22 cells, were hardly detected in etoposide-treated HOC313 cells under non-permissive conditions, suggesting a contribution of p73 reduction to etoposide resistance in HOC313 cells. Finally, the caspase-9 inhibitor Ac-LEHD-CHO or caspase-9 siRNA blocked etoposide-induced caspase-8 activation, Bid cleavage, and apoptosis in both cell lines, indicating that p53/p73-dependent caspase-8 activation lies downstream of mitochondria.</p> <p>Conclusions</p> <p>we conclude that p53 and p73 can act as upstream regulators of caspase-8, and that caspase-8 is an essential mediator of the p53/p73-dependent apoptosis induced by etoposide in HNSCC cells. Our data suggest the importance of caspase-8-mediated positive feedback amplification in the p53/p73-dependent apoptosis induced by etoposide in HNSCC cells.</p

Interplay between Nitrogen Dopants and Native Point Defects in Graphene

To understand the interaction between nitrogen dopants and native point defects in graphene, we have studied the energetic stability of N-doped graphene with vacancies and Stone-Wales (SW) defect by performing the density functional theory calculations. Our results show that N substitution energetically prefers to occur at the carbon atoms near the defects, especially for those sites with larger bond shortening, indicating that the defect-induced strain plays an important role in the stability of N dopants in defective graphene. In the presence of monovacancy, the most stable position for N dopant is the pyridinelike configuration, while for other point defects studied (SW defect and divacancies) N prefers a site in the pentagonal ring. The effect of native point defects on N dopants is quite strong: While the N doping is endothermic in defect-free graphene, it becomes exothermic for defective graphene. Our results imply that the native point defect and N dopant attract each other, i.e., cooperative effect, which means that substitutional N dopants would increase the probability of point defect generation and vice versa. Our findings are supported by recent experimental studies on the N doping of graphene. Furthermore we point out possibilities of aggregation of multiple N dopants near native point defects. Finally we make brief comments on the effect of Fe adsorption on the stability of N dopant aggregation.Comment: 10 pages, 5 figures. Figure 4(g) and Figure 5 are corrected. One additional table is added. This is the final version for publicatio

Constraints on a vacuum energy from both SNIa and CMB temperature observations

We investigate the cosmic thermal evolution with a vacuum energy which decays into photon at the low-redshift. We assume that the vacuum energy is a function of the scale factor that increases toward the early universe. We put on the constraints using recent observations of both type Ia supernovae (SNIa) by Union-2 compilation and the cosmic microwave background (CMB) temperature at the range of the redshift 0.01 < z < 3. From SNIa, we find that the effects of a decaying vacuum energy on the cosmic expansion rate should be very small but could be possible for z < 1.5. On the other hand, we obtain the severe constraints for parameters from the CMB temperature observations. Although the temperature can be still lower than the case of the standard cosmological model, it should only affect the thermal evolution at the early epoch.Comment: 9 pages, 3 figures, 1 tables, submitted to Advances in Astronom

Dependency of tensile strength of ductile cast iron on strain rate and temperature

The dependency of the tensile strength σ smooth B and the notch strength σ notch B on strain rate and temperature were investigated for conventional ferrite-pearlite type ductile cast iron (JIS-FCD500) to make clear the applicability of ductile cast iron to components for welded steel structures. High speed tensile tests were conducted on notched and smooth specimens with varying strain rate and temperature. Charpy absorbed energy was also evaluated on notched specimen with varying temperature. It is found that the tensile strength is in a good relationship with strain rate-temperature parameter R for the wide range of strain rate and temperature. With decreasing R parameter, both σ smooth B and σ notch B increase even when Charpy absorbed energy starts decreasing. It should be noted that the notch strength σ notch B is always larger than the tensile strength at room temperature σ smooth B, RT in the range of R parameter required for the welded structures. Therefore, the tensile strength σ smooth B, RT is confirmed to be useful for the structural design.12th International Conference on Damage Assessment of Structures, 10–12 July 2017, Kitakyushu, Japa

Conditions for notch strength to be higher than static tensile strength in high–strength ductile cast iron

In this study, notch strength σ B notch was studied for a wide range of testing speed and temperature in comparison with the static tensile strength at room temperature σ B, RT smooth. High–speed tensile tests were conducted on high–Si ductile cast iron, conventional ferrite–pearlite ductile cast iron, and fully pearlitic ductile cast iron at a stroke speed ranging between 8.5 × 10−3–2.7 × 102 mm/s (strain rate of 2.1 × 10−4–1.8 × 101 s−1) and temperature ranging between −180°C–22°C. Then, σ B notch and σ B,RT smooth were compared in terms of the strain rate–temperature parameter R = T ln (A/ ) to evaluate the combined influence of the strain rate and temperature T. It was found that the notch strength σ B notch can be expressed as a unique master curve in terms of R parameter for each material. Then, a notch–strengthening threshold criterion R ≧ Rth was proposed to describe the lowest service temperature and highest strain rate that can be applied to the structural components. Under the condition R ≧ Rth, σ B notch is always larger than σ B,RT smooth , and therefore, notched components can be used safely. In other words, if R ≧ Rth, σ B,RT smooth can be used to evaluate the notched components in machine design to prevent instantaneous fractures

Antioxidant and antiproliferative activities of Malaysian sea cucumber, (Holothuria edulis Lesson), extracts

Sea cucumber is a marine invertebrate of the phylum Echinodermata and the class Holothuroidea that found on the sea floor worldwide. In Asia, many of sea cucumber species are considered as traditional food items and have been used in featment of numerous diseases such as eczema, arthritis and hypertension. Previous scientific studies have shown multiple biological activities of sea cucumber species as antinociceptive, antimicrobial and antifungal properties. This study was conducted to investigate the antioxidant and antiproliferative activities of aqueous and organic extracts from sea cucumber, Holothuria edulis. Two different free radical systems were used to evaluate antioxidant activity of H. edulis, stable radical l,l-diphenyl-2- picrylhydrazyl (DPPH.) and linoleic acid free radical mediated p-carotene bleaching. In addition, Folin-Ciocalteau reagent was used to determine the total phenolic content of the exfacts. The inhibitory effect of the exfacts on proliferation of MCF-7 (human breast adenocarcinoma) and TEI (Human esophageal squamous cell carcinoma) human cancer cell lines were demonstrated by 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Our data showed that the gallic acid equivalent (GAE) of the total phenolic content in aqueous extract (GAE : 7.33 mglg) is higher than an organic extact (GAE = 2.17 mglg). An aqueous extract also exhibited higher.antioxidant capacity by using DPPH assay (ICso = 2.04 mg/ml vs. 8.73 mlmL in organic extract), as well as by using p-carotene bleaching assay (Antioxidant Activity : 42.69 %o vs. 28.52 % in organic extract). On the other hand, an organic extact showed higher antiproliferative effect against MCF-7 and TEI cancer cells, giving ICso : 28.0 and 17.5 pdmL, respectively than aqueous extract, that gave ICso : 133.0 pilmL against MCF- '7 and76.0 pgmL against TEl. In conclusion, frndings of this study revealed that H. edulis as a promising source ofnatural antioxidants and anticancer products

TNF-α is essential in the induction of fatal autoimmune hepatitis in mice through upregulation of hepatic CCL20 expression.

It is unclear what roles TNF-α has in the development of autoimmune hepatitis (AIH) and whether AIH is responsive to anti-TNF-α. We recently developed a mouse model of fatal AIH that develops in PD-1-deficient mice thymectomized three days after birth, finding that CCR6-CCL20 axis-dependent migration of dysregulated splenic T cells is crucial to induce AIH. In this study, we show the indispensable role of TNF-α in the development of AIH. Administering anti-TNF-α prevented the induction, but treatment by anti-TNF-α after the induction did not suppress progression. Administering anti-TNF-α did not prevent splenic T-cell activation, but did suppress hepatic CCL20 expression. In contrast, administering anti-CCL20 suppressed AIH but not elevated serum TNF-α levels. TNF-α stimulation enhanced CCL20 expression in hepatocytes. These findings suggest that TNF-α is essential in the induction of AIH through upregulation of hepatic CCL20 expression, which allows migration of dysregulated splenic T cells