Demonstration of a powerful mutagenic dinitropyrene in airborne particulate matter

Of the many nitroarenes, dinitropyrenes (DNPs) have the potential to revert Salmonella typhimurium his- mutants. This study was conducted to investigate the potential mutagens present in airborne particulate matter collected in Santiago, Chile. 5 organic substances extracted with dichloromethane showed mutagenic rates of from 38.9 to 287 revertants per m3 of air for S. typhimurium his- strain TA98 without S9 mix. 4 of the samples had greatly reduced mutagenicity for strain TA98/1,8DNP6 but not for strain TA98NR. The 1-nitropyrene (1-NP) content accounted for 0.06-0.15 microgram per g of particulate, as determined by high-performance liquid chromatography (HPLC), but the contribution of the compound to mutagenicity was less than 1% of the total activity. On the other hand, by using two columns in the HPLC, DNPs of 1,6- and 1,8-isomers were detected in the samples pooled after the determination of 1-NP, and the amount of the derivatives was about 0.2 microgram per g of particulate matter.     

A Novel PHB Depolymerase from a Thermophilic Streptomyces Sp.

A novel PHB depolymerase from a thermophilic Streptomyces sp. MG was purified to homogeneity by hydrophobic interaction chromatography and gel filtration. The molecular mass of the purified enzyme was 43 kDa as determined by size exclusion chromatography and 41 kDa by SDS-PAGE. The optimum pH and temperature were 8.5 and 60 °C respectively. The enzyme was stable at 50 °C and from pH 6.5–8.5. The enzyme hydrolyzed not only bacterial polyesters, i.e. poly(3-hydroxybutyric acid and poly(3-hydroxybutyrate-co-3-hydroxyvalerate), but also synthetic, aliphatic polyesters such as polypropiolactone, poly(ethylene adipate) and poly(ethylene succinate). Revisions requested 9 November 2005; Revisions received 12 December 2005     

Application of bipolar electrodialysis on recovery of free lactic acid after simultaneous saccharification and fermentation of cassava starch

The efficiency of bipolar electrodialysis (BED) for the recovery of lactic acid from fermentation broth was evaluated. Three systems of BED (bipolar-anion, bipolar-cation and bipolar-anion-cation) at fixed voltage (20 V) were compared using a model solution of ammonium lactate (100 g l(-1)). Results showed that bipolar-anion (BED-anion) was the most beneficial in terms of lactate flux, current efficiency, energy consumption and recovery ratio. Consequently, BED-anion was used to purify lactic acid from fermentation broth which had been pre-treated with mono-polar electrodialysis (MED). The final lactic acid concentration and lactate flux obtained were 144 g l(-1) and 393 g m(-2) h(-1), respectively. Using the two-step process (MED and BED-anion) the concentration of fermentation broth was increased by 33% and the total energy consumption was 2.76 kW h kg(-1).     

A major factor in gravitropism in radish hypocotyls is the suppression of growth on the upper side of hypocotyls

The changes in length on the two opposite sides of etiolated radish (Raphanus sativus) hypocotyls prior to, and following gravitropic stimulation, were measured using an infrared-imaging system. It was observed that the growth suppression on the upper side began first at least 10 min after the onset of gravitropic stimulation, and after 30 min the acceleration in growth on the lower side started. The gravitropic curvature was steadily induced from 10 min. When radish hypocotyls were switched from a vertical to horizontal position for different durations and then replaced to the vertical position, the growth suppression on the gravity-stimulated (upper) side was observed in all cases, but the acceleration in growth on the opposite (lower) side appeared only in continuously gravity-stimulated seedlings, although it occurred later than the growth suppression on the upper side. These results suggest that the suppression in growth on the upper side of the hypocotyls is a direct effect of gravitropic stimulation, but not the acceleration on the lower side. When 4-methylthio-3-butenyl isothiocyanate (4-MTBI), which has an inhibitory activity against radish hypocotyl growth, was applied on the one side of radish hypocotyls and then the 4-MTBI-applied side or opposite side was placed in a horizontal position, the former showed greater bending than the control, suggesting that the growth suppression on the upper side is enhanced and maintained with MTBI application there. In the latter case, the seedlings showed less bending than the control, suggesting a decrease in growth on the lower side with MTBI application. All the results suggest that gravitropism of radish hypocotyls may be caused by an increase in growth-inhibiting substance(s) induced with gravitropic stimulation in the upper side, inducing growth inhibition there.     

Culture methods of human liver cells

Attempts to isolate and cultivate human liver cells have been described. Many viable liver cells have been obtained when dissociated with collagenase followed by dispase. The morphology and differentiated functions have been maintained for more than 3 weeks when human fetal liver cells were cultured not only in medium containing 10(-3) M hydrocortisone, but also on collagen gel substrates with 5 x 10(-7) M hydrocortisone. The colony-forming capacity of primary cultured fetal human livers has also been described in the presence of conditioned medium.     

Bioorganic synthesis of end-capped anti-HIV peptides by simultaneous cyanocysteine-mediated cleavages of recombinant proteins

Bioorganic synthesis of N- and C-terminal end-capped peptides by two simultaneous S-cyanocysteine-mediated cleavages of recombinant proteins is described. This approach is demonstrated in the preparation of anti-HIV fusion inhibitory peptides.     

Computational design of a sulfoglucuronide derivative fitting into a hydrophobic pocket of dengue virus E protein

We performed first-principles calculations based on the ab initio fragment molecular orbital method on dengue virus envelope protein with a hydrophobic ligand, octyl-β-d-glucose to develop an entry inhibitor. As several polar amino acid residues are present at the edge of the pocket, the glucose moiety was chemically modified with hydrophilic groups. Introduction of both sulfated and carboxylated groups on glucose enhanced not only binding affinity to the protein but also inhibition of dengue virus entry. Octyl-2-O-sulfo β-d-glucuronic acid may serve as a molecular probe to study the dengue virus entry process.     

Metarhizium aciculare sp. nov. for euvesperins A and B producing Metarhizium strains

We have already found some Metarhizium isolates produce euvesperins A and B, which were circumventors of arbekacin resistance in MRSA. These isolates were obtained from soil samples collected from the Izu islands and Kannami town, Sizuoka, Japan. Using a combination of micro-morphological characteristics and multigene (SSU, LSU, TEF) phylogenics, the isolates were identified as a previously underscribed species of Metarhizium. Phylogenetically, the species is close to M. carneum but it is distinguished morphologically from M. carneum by size and the surface structure of conidia.     

A modified method for isolating poly(vinyl alcohol)-degrading bacteria and study of their degradation patterns

An addition of catalase or peroxidase into an agar plate containing poly(vinyl alcohol) (PVA), was effective for the isolation of PVA-degrading microorganisms. A Gram-negative bacterium, strain TK-2 (-group of proteobacteria), rapidly degraded a high molecular weight PVA to low molecular weight material after 1 day thereby producing oligomers of PVA as shown by gel permeation chromatography. Conversely, Sphingomonas strain TJ-7 did not produce any PVA oligomers, suggesting that the strain TJ-7 degraded PVA from the terminal ends of the molecules, whereas the strain TK-2 cleaved PVA at random.     

Effects of serum and serum-derived factors on the growth and production of α-fetoprotein and albumin by human hepatoma cell lines

A serum-free culture system of human hepatoma cell lines (HuH-6 and HuH-7) was used to investigate the activity of bovine serum (BS) and of serum-derived factors on the growth and production of -fetoprotein (AFP) and albumin. At higher concentrations, dialyzed BS was inhibitory to the growth of HuH-6 and caused reduction of the level of AFP production by the cells. AFP and albumin levels in HuH-6 and HuH-7 were reduced or unchanged by fetuin, bovine serum albumin (BSA) and transferin (TF), although no cytotoxicity was shown by any of them. Commercial preparations of platelet-derived growth factor exhibited cytotoxicity to HuH-6 and HuH-7 and induced a decrease of AFP and albumin levels in a dose-dependent manner. Transforming growth factor (TGF-) exhibited no cytotoxicity to HuH-6. AFP levels in HuH-6 were unchanged with 1000 pg/ml TGF-, but albumin levels were decreased. TGF-7 at a concentration of 1000 pg/ml was cytotoxic to HuH-7 and AFP levels were a little increased. Albumin levels, however, were unchanged. Following exposure to cycloheximide, AFP and albumin levels in HuH-6 were inhibited.Abbreviations AFP -fetoprotein - BS bovine serum - BSA bovine serum albumin - EDTA ethylenediaminetetraaceticacid - ELISA enzyme-linked immunosorbent assay - HBSS Hank's balanced salt solution - PBS phosphate buffered saline - PDGF platelet-derived growth factor - TF transferrin - TGF-\ transforming growth factor beta