Changes in the antibiotic production by co-culture of Rhizopus peka P8 and Bacillus subtilis IFO3335

The co-culture of Bacillus subtilis IFO 3335 with Rhizopus peka P8 or Rhizopus oligosporus P12 in liquid medium was found to increase production of antibiotic activity and to alter the spectrum of activity relative to the pure cultures. However, a mixed culture of Rhizopus arrhizus P7 and Rhizopus oryzae P17 did not produce antibiotic activity. The concentration, ratio, and time of addition of B. subtilis to the R. peka culture was found to influence antibiotic yields. Solid-state fermentations using mixed cultures of R. peka and B. subtilis were investigated. The growth of Escherichia coli IFO 3792 as a target bacterium was inhibited by the mixed culture. These results suggest the possibility of biopreservation of fermented foods by novel co-culture systems.     

Selenoneine, a Novel Selenium-Containing Compound, Mediates Detoxification Mechanisms against Methylmercury Accumulation and Toxicity in Zebrafish Embryo

The selenium (Se)-containing antioxidant selenoneine (2-selenyl-N _α,N _α,N _α-trimethyl-l-histidine) has recently been discovered to be the predominant form of organic Se in tuna blood. Although dietary intake of fish Se has been suggested to reduce methylmercury (MeHg) toxicity, the molecular mechanism of MeHg detoxification by Se has not yet been determined. Here, we report evidence that selenoneine accelerates the excretion and demethylation of MeHg, mediated by a selenoneine-specific transporter, organic cations/carnitine transporter-1 (OCTN1). Selenoneine was incorporated into human embryonic kidney HEK293 cells transiently overexpressing OCTN1 and zebrafish blood cells by OCTN1. The K _m for selenoneine uptake was 13.0 μM in OCTN1-overexpressing HEK293 cells and 9.5 μM in zebrafish blood cells, indicating high affinity of OCTN1 for selenoneine in human and zebrafish cells. When such OCTN1-expressing cells and embryos were exposed to MeHg–cysteine (MeHgCys), MeHg accumulation was decreased and the excretion and demethylation of MeHg were enhanced by selenoneine. In addition, exosomal secretion vesicles were detected in the culture water of embryos that had been microinjected with MeHgCys, suggesting that these may be responsible for MeHg excretion and demethylation. In contrast, OCTN1-deficient embryos accumulated MeHg, and MeHg excretion and demethylation were decreased. Furthermore, Hg accumulation was decreased in OCTN1-overexpressing HEK293 cells, but not in mock vector-transfected cells, indicating that selenoneine and OCTN1 can regulate MeHg detoxification in human cells. Thus, the selenoneine-mediated OCTN1 system regulates secretory lysosomal vesicle formation and MeHg demethylation.     

Further studies on hepatitis C virus NS5B RNA-dependent RNA polymerase inhibitors toward improved replicon cell activities: benzimidazole and structurally related compounds bearing the 2-morpholinophenyl moiety

Following the discovery of JTK-109 (1) as a potent inhibitor of hepatitis C virus NS5B RNA-dependent RNA polymerase, [(a) Hirashima, S.; Suzuki, T.; Ishida, T.; Noji, S.; Yata, S.; Ando, I.; Komatsu, M.; Ikeda, S.; Hashimoto, H. J. Med. Chem.2006, 49, 4721. (b) Hashimoto, H.; Mizutani, K.; Yoshida, A. Int. Patent Appl. WO 01/47883, 2001.] further studies toward the improvement of the cellular potency have been performed. A greater than 40-fold improvement was achieved through replacing the biphenyl moiety with a 2-morpholinophenyl group and the benzimidazole ring with the tetracyclic scaffold to afford compound 7 with an excellent replicon potency (EC(50)=7.6 nM).     

Structure and Bitterness in Flavanone Glycosides

Naringenin-7-β-kojibioside, -7-β-sophoroside, -7-[α-d-galactosyl(l→2)β-d-glucoside], -7-[β-d-glucosyl(l→2)β-d-galactoside], and also hesperetin-7-β-kojibioside and -7-β-sophoroside were prepared by the coupling of naringenin or hesperetin with the α-acetobromo derivatives of the appropriate disaccharides, followed by saponification.

Their relative bitterness values were discussed in comparison with naringin and neo-hesperidin.     

O uptake rate measurements as a novel tool to study shear effects on suspended strawberry cells

Despite the same mean volumetric power input of 19 and 47 W/m 3 , the specific oxygen uptake rate (OUR S ) of strawberry ( Fragaria ananassa) cell suspensions was higher in bioreactors equipped with a Rushton Turbine (4.4 and 6.2 3 10 -5 mol O 2 /kg.s) than with an anchor stirrer (2.5 and 4.6 3 10 -5 mol O 2kg.s). The increase in OUR S was caused by stress-activated respiration and appeared to be correlated with the locally dissipated power input. OUR S was corrected for the increase in surface through aggregate break-up and reached a maximum of 6.0 3 10 -5 mol O 2kg.s when agitating with approximately 200 kW/m 3 locally dissipated power input.