Acetic acid production using a fermentor equipped with a hollow fiber filter module

The continuous production of acetic acid by Acetobacter aceti M23 was carried out using a fermentor equipped with a hollow fiber filter module. The culture continued for 830 h with various dilution rates, which were changed stepwisely from low to high. The final cell concentration was 21.9 g dry cell/L and the maximum productivity of acetic acid was 12.7 g/L.h for the exit acetic acid concentration of about 50 g/L. The productivity was higher than any literature's values surveyed so far. The cell concentration was 62.8 times and the productivity was 4.6 times as high as those of the fermentor without the filter module. The productivity increased with the increase of dilution rate up to 0.3 h(-1). It is interesting to note that the viable cell concentration was kept almost constant about 1.1 x 10(9) cells/ml in spite of the increase of dilution rate. Use of oxygen-rich air was indispensable to establish the high productivity of acetic acid.     

Schizosaccharomyces pombe Spk1 is a tyrosine-phosphorylated protein functionally related to Xenopus mitogen-activated protein kinase.

Mitogen-activated protein kinase (MAPK) and its direct activator, MAPK kinase (MAPKK), have been suggested to play a pivotal role in a variety of signal transduction pathways in higher eukaryotes. The fission yeast Schizosaccharomyces pombe carries a gene, named spk1, whose product is structurally related to vertebrate MAPK. Here we show that Spk1 is functionally related to Xenopus MAPK. (i) Xenopus MAPK partially complemented a defect in the spk1- mutant. An spk1- diploid strain could not sporulate, but one carrying Xenopus MAPK could. (ii) Both Spk1 and Xenopus MAPK interfered with sporulation if overexpressed in S. pombe cells. (iii) Spk1 underwent tyrosine phosphorylation as does Xenopus MAPK. Tyrosine phosphorylation of Spk1 appeared to be dependent upon mating signals because it occurred in homothallic cells but not in heterothallic cells. Furthermore, this phosphorylation was diminished in a byr1 disruptant strain, suggesting that spk1 lies downstream of byr1, which encodes a MAPKK homolog in S. pombe. Taken together, the MAPKK-MAPK cascade may be evolutionarily conserved in signaling pathways in yeasts and vertebrates.     

Identification and Characterization of a Novel Lysophosphatidic Acid Receptor, p2y5/LPA6

p2y5 is an orphan G protein-coupled receptor that is closely related to the fourth lysophosphatidic acid (LPA) receptor, LPA₄. Here we report that p2y5 is a novel LPA receptor coupling to the G₁₃-Rho signaling pathway. “LPA receptor-null” RH7777 and B103 cells exogenously expressing p2y5 showed [³H]LPA binding, LPA-induced [³⁵S]guanosine 5′-3-O-(thio)triphosphate binding, Rho-dependent alternation of cellular morphology, and G_s/13 chimeric protein-mediated cAMP accumulation. LPA-induced contraction of human umbilical vein endothelial cells was suppressed by small interfering RNA knockdown of endogenously expressed p2y5. We also found that 2-acyl-LPA had higher activity to p2y5 than 1-acyl-LPA. A recent study has suggested that p2y5 is an LPA receptor essential for human hair growth. We confirmed that p2y5 is a functional LPA receptor and propose to designate this receptor LPA₆.     

Antifungal and fungicidal activities of tea extract and catechin against Trichophyton

We examined tea extract, (-) epigallocatechin gallate (EGCg) and theaflavin digallate (TF3) for their antifungal and fungicidal activities against Trichophyton mentagrophytes, T. rubrum, Candida albicans and Cryptococcus neoformans. Tea extract (2.5%) inhibited completely the growth of both T. mentagrophytes and T. rubrum. EGCg at 2.5 mg/ml failed to inhibit their growth, whereas TF3 at 0.5 mg/ml inhibited the growth. EGCg (1mg/ml) showed no fungicidal activity against Trichophyton. TF3 (1mg/ml) killed Trichophyton by a long time contact (72-96 hrs). Tea extract showed a fungicidal activity against Trichophyton in a dose- and contact time-dependent manner. It did not inhibit the growth of C. albicans, but at a high concentration, inhibited slightly the growth of C. neoformans. It had no fungicidal activity against C. albicans or C. neoformans.     

Koningic Acid (a Potent Glyceraldehyde-3-Phosphate Dehydrogenase Inhibitor)-Induced Fragmentation and Condensation of DNA in NG108-15 Cells

Abstract: We examined nitric oxide (NO)-induced cell death in NG108-15 cells using NO donors. Both sodium nitroprusside (SNP) and S -nitroso- N -acetylpenicillamine caused lactate dehydrogenase (LDH) leakage from NG108-15 cells. NO is known to increase the amount of radioisotopic labeled glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in the presence of [³²P]NAD and to inhibit the enzyme activity. To clarify the relationship between the NO-induced inhibition of GAPDH activity and cell death, we studied the effect of koningic acid (KA), a potent selective inhibitor of GAPDH. Both SNP and KA elicited LDH leakage, chromosomal condensation, and fragmentation of nuclei in NG108-15 cells. Gel electrophoretic analysis of cellular DNA extracted from SNP- and KA-treated cells revealed the internucleosomal DNA fragmentation typical of apoptosis in these cultures. The results suggested that in NG108-15 cells, (a) the inhibition of GAPDH activity results in apoptosis and (b) SNP-induced cell death is partly due to the NO-induced inhibition of GAPDH, perhaps by stimulating the binding of NAD to GAPDH.     

A toxic monomeric conformer of the polyglutamine protein

Polyglutamine (polyQ) diseases are classified as conformational neurodegenerative diseases, like Alzheimer and Parkinson diseases, and they are caused by proteins with an abnormally expanded polyQ stretch. However, conformational changes of the expanded polyQ protein and the toxic conformers formed during aggregation have remained poorly understood despite their important role in pathogenesis. Here we show that a beta-sheet conformational transition of the expanded polyQ protein monomer precedes its assembly into beta-sheet-rich amyloid-like fibrils. Microinjection of the various polyQ protein conformers into cultured cells revealed that the soluble beta-sheet monomer causes cytotoxicity. The polyQ-binding peptide QBP1 prevents the toxic beta-sheet conformational transition of the expanded polyQ protein monomer. We conclude that the toxic conformational transition, and not simply the aggregation process itself, is a therapeutic target for polyQ diseases and possibly for conformational diseases in general.     

Impact of engagement of FcepsilonRI and CC chemokine receptor 1 on mast cell activation and motility

CC chemokines participate in the recruitment and activation of immune cells through CC chemokine receptors (CCRs). Here, we report that cross-talk between CCR1-mediated signaling pathway and FcepsilonRI-mediated signaling pathway affects degranulation positively but affects chemotaxis of mast cells adversely. Costimulation via FcepsilonRI engagement with IgE/antigen and CCR1 engagement with recombinant human CCL3 synergistically enhanced degranulation in rat basophilic leukemia-2H3 cells expressing human CCR1 (RBL-CCR1). Interestingly, FcepsilonRI engagement inhibited CCL3-mediated chemotaxis and membrane ruffling of RBL-CCR1 cells. Small GTP-binding proteins of the Rho family, Rac, Cdc42, and Rho control chemotaxis by mediating the reorganization of the actin cytoskeleton. Both a Rho inhibitor C3 exoenzyme and a Rho kinase (ROCK) inhibitor Y-27632 inhibited chemotaxis of RBL-CCR1 cells toward CCL3, indicating that activation of the Rho/ROCK signaling pathway is required for the CCL3-mediated chemotaxis of the cells. Costimulation with IgE/antigen and CCL3 enhanced Rac and Cdc42 activation but decreased ROCK activation in RBL-CCR1 cells compared with that in the cells stimulated with CCL3 alone. These results suggest that costimulation via FcepsilonRI and CCR1 engagements induced 1) inhibition of membrane ruffling, 2) decreased ROCK activation, and 3) reciprocal imbalance between Small GTP-binding proteins of the Rho family, which result in the inhibition of chemotaxis of RBL-CCR1 cells. The cross-talk between FcepsilonRI-mediated signaling pathway and CCR-mediated signaling pathway would induce optimal activation and arrested chemotaxis of mast cells, thus contributing to allergic inflammation.     

Bioelectronic sniffers for ethanol and acetaldehyde in breath air after drinking

Two kinds of bioelectronic gas sensors (bio-sniffer) incorporating alcohol oxidase (AOD) and aldehyde dehydrogenase (ALDH) were developed for the convenient analysis of ethanol and acetaldehyde in expired gas, respectively. The sniffer devices for gaseous ethanol and acetaldehyde were constructed by immobilizing enzyme on electrodes covered with filter paper and hydrophilic PTFE membrane, respectively. The AOD and ALDH sniffers were used in the gas phase to measure ethanol vapor from 1.0 to 500 ppm, and acetaldehyde from 0.11 to 10 ppm covering the concentration range encountered in breath after alcohol consumption. Both bio-sniffers displayed good gas selectivity which was attributed to the substrate specificity of the relevant enzymes (AOD and ALDH) as gas recognition material. From the results of physiological application, the bio-sniffers could monitor the concentration changes in breath ethanol and acetaldehyde after drinking. The ethanol and acetaldehyde concentrations in expired air from ALDH2 [-] (aldehyde dehydrogenase type 2 negative) subjects were higher than that of the ALDH2 [+] (positive) subjects. The results indicated that the lower activity of ALDH2 induced an adverse effect on ethanol metabolism, leading to ethanol and acetaldehyde remaining in the human body, even human expired air.