A new chemoheterotrophic bacterium catalyzing water-gas shift reaction

A new bacterium, Citrobacter sp. Y19, catalyzing the water-gas shift reaction was isolated from an anaerobic wastewater sludge digester. It grew aerobically with a high specific growth rate of 0.7 h^–1 in a mineral salt medium supplemented with yeast extract and Bacto-tryptone, and produced H₂ under anaerobic conditions after the cells were transferred to tryptone-deleted medium. The maximum H₂ production rate was 33 mmol H₂ g^–1 cell h, which was maintained for about 200 h. This is the first report on a chemoheterotrophic bacterium which utilizes CO with the production of H₂ and CO₂.     

The Disulfide Bond Arrangement in the Extracellular Domain of the Activin Type II Receptor

The initial step in the signaling cascade of the growth factor activin involves its binding to the extracellular domain of the activin type II receptor. This receptor domain contains 10 cysteine residues which are engaged in intramolecular disulfide bonds. To elucidate the structural framework of this domain we have characterized its disulfide-bonding pattern using an extracellular fragment of the receptor which binds activin A with high affinity. By combining proteolysis with mass spectroscopy and chemical sequence analysis, the disulfide connectivity was determined to be as follows: C1–C3, C2–C4, C5–C8, C6–C7, and C9–C10. A similar disulfide arrangement occurs in a family of snake toxins for which the three-dimensional structure is known.     

Development of an amphiphilic matrix for immobilization of <Emphasis Type="Italic">Candida antartica</Emphasis> lipase B for biodiesel production

Biodiesel has been greatly interested as an alternative fuel and is produced by a transesterification reaction of oil with alcohol. Recently, microbial lipases have been used for biodiesel production. Among the microbial lipase, immobilized Candida antartica lipase B (CALB) is the most widely used. However, CALB is unstable and shows low catalytic efficiency in the reaction media because the reaction media contains a high concentration of methanol and the lipase is also inhibited by the by-product glycerol. In this study, to overcome these limitations, we developed an amphiphilic matrix to immobilize CALB. The immobilized lipase in an amphiphilic matrix with 80% ethyltrimethoxysilane (ETMS) in tetramethoxysilane (TMOS) and pretreated with oil showed the highest specific activity and biodiesel conversion ratio; about 90% biodiesel conversion in 24 h at an initial molar ratio of 1: 1 (oil: methanol) with stepwise methanol feeding in order to adjust the net molar ratio to be 1: 3.     

d-Glucosamine down-regulates HIF-1α through inhibition of protein translation in DU145 prostate cancer cells

d-Glucosamine has been reported to inhibit proliferation of cancer cells in culture and in vivo. In this study we report a novel response to d-glucosamine involving the translation regulation of hypoxia inducible factor (HIF)-1α expression. d-Glucosamine caused a decreased expression of HIF-1α under normoxic and hypoxic conditions without affecting HIF-1α mRNA expression in DU145 prostate cancer cells. d-Glucosamine inhibited HIF-1α accumulation induced by proteasome inhibitor MG132 and prolyl hydroxylase inhibitor DMOG suggesting d-glucosamine reduces HIF-1α protein expression through proteasome-independent pathway. Metabolic labeling assays indicated that d-glucosamine inhibits translation of HIF-1α protein. In addition, d-glucosamine inhibited HIF-1α expression induced by serum stimulation in parallel with inhibition of p70S6K suggesting d-glucosamine inhibits growth factor-induced HIF-1α expression, at least in part, through p70S6K inhibition. Taken together, these results suggest that d-glucosamine inhibits HIF-1α expression through inhibiting protein translation and provide new insight into a potential mechanism of the anticancer properties of d-glucosamine.     

Clusterin regulates transthyretin amyloidosis

Transthyretin (TTR) is a human disease-associated amyloidogenic protein that has been implicated in senile systemic amyloidosis (SSA) and familial amyloidotic polyneuropathy (FAP). FAP typically results in severe and early-onset disease, and the only therapy established so far is liver transplantation; thus, developing new strategies for treating FAP is of paramount interest. Clusterin has recently been proposed to play a role as an extracellular molecular chaperone, affecting the fibril formation of amyloidogenic proteins. The ability of clusterin to influence amyloid fibril formation prompted us to investigate whether clusterin is capable of inhibiting TTR amyloidosis. Here, we report that clusterin strongly interacts with wild-type TTR and TTR variants V30M and L55P under acidic conditions, and blocks the amyloid fibril formation of TTR variants. In particular, the amyloid fibril formation of V30M TTR in the presence of clusterin is reduced to level similar to wild-type TTR. We also demonstrated that clusterin is an effective inhibitor of L55P TTR amyloidosis, the most aggressive form of TTR diseases. The mechanism by which clusterin inhibits TTR amyloidosis appears to be through stabilization of TTR tetrameric structure. These findings suggest the possibility of using clusterin as a therapeutic agent for TTR amyloidosis.     

Neuromedin B induces angiogenesis via activation of ERK and Akt in endothelial cells

Neuromedin B (NMB) is one of the bombesin-like peptides in mammals. Recently, bombesin-like peptides have been characterized as growth factors in highly vascularized tumors. In this study, we report that NMB potently stimulates in vivo neovascularization in a mouse Matrigel plug and the sprouting of endothelial cells ex vivo in rat aortic rings. In addition, NMB increases the migration and tube formation in human umbilical vein endothelial cells (HUVECs). Moreover, treatment of HUVECs with NMB activates the extracellular signal-regulated kinase 1/2 (ERK_1/2), Akt, and endothelial nitric oxide synthase (eNOS) and increases the level of NO production in a dose- and time-dependent manner. Furthermore, ERK activation and angiogenic sprouting in response to NMB are significantly blocked by the MEK inhibitor. Inhibition of phosphatidylinositol 3-kinase (PI3K) suppresses the NMB-stimulated tubular formation of HUVECs, along with reduction in the phosphorylation of Akt and eNOS. Taken together, these results indicate that NMB is a novel angiogenic peptide, and its angiogenic activity is mediated by activating the MEK/ERK- and PI3K/Akt/eNOS-dependent pathways. This study suggests that NMB may play important roles in mediating a variety of pathophysiological angiogenesis.     

Bacterial community composition and diversity of a full-scale integrated fixed-film activated sludge system as investigated by pyrosequencing

The integrated fixed-film activated sludge (IFAS) system is a variation of the activated sludge wastewater treatment process, in which hybrid suspended and attached biomass is used to treat wastewater. Although the function and performance of the IFAS system are well studied, little is known about its microbial community structure. In this study, the composition and diversity of the bacterial community of suspended and attached biomass samples were investigated in a full-scale IFAS system using a highthroughput pyrosequencing technology. Distinct bacterial community compositions were examined for each sample and appeared to be important for its features different from conventional activated sludge processes. The abundant bacterial groups were Betaproteobacteria (59.3%), Gammaproteobacteria (8.1%), Bacteroidetes (5.2%), Alphaproteobacteria (3.9%), and Actinobacteria (3.2%) in the suspended sample, whereas Actinobacteria (14.6%), Firmicutes (13.6%), Bacteroidetes (11.6%), Betaproteobacteria (9.9%), Gammaproteobacteria (9.25%), and Alphaproteobacteria (7.4%) were major bacterial groups in the attached sample. Regarding the diversity, totals of 3,034 and 1,451 operational taxonomic units were identified at the 3% cutoff for the suspended and attached samples, respectively. Rank abundance and community analyses demonstrated that most of the diversity was originated from rare species in the samples. Taken together, the information obtained in this study will be a base for further studies relating to the microbial community structure and function of the IFAS system.