Expression profiles and functional characterization of common carp (Cyprinus carpio) T2Rs

Bitter taste perception is mediated by a family of G protein-coupled receptors (T2Rs) in vertebrates. Common carp (Cyprinus carpio), which has experienced an additional round of whole genome duplication during the course of evolution, has a small number of T2R genes similar to zebrafish, a closely related cyprinid fish species, and their expression pattern at the cellular level or their cognate ligands have not been elucidated yet. Here, we showed through in situ hybridization experiments, that three common carp T2R (ccT2R) genes encoding ccT2R200-1, ccT2R202-1, and ccT2R202-2, were specifically expressed in the subsets of taste receptor cells in the lips and gill rakers. ccT2R200-1 was co-expressed with genes encoding downstream signal transduction molecules, such as PLC-β2 and Gαia. Heterologous expression system revealed that each ccT2R showed narrowly, intermediately, or broadly tuned ligand specificity, as in the case of zebrafish T2Rs. However, ccT2Rs showed different ligand profiles from their orthologous zebrafish T2Rs previously reported. Finally, we identified three ccT2Rs, namely ccT2R200-1, ccT2R200-2, and ccT2R203-1, to be activated by natural bitter compounds, andrographolide and/or picrotoxinin, which elicited no response to zebrafish T2Rs, in a dose-dependent manner. These results suggest that some ccT2Rs may have evolved to function in the oral cavity as taste receptors for natural bitter compounds found in the habitats in a species-specific manner.     

Acetic acid production by Acetobacter aceti in a silicone tube bioreactor

Summary Continuous acetic acid fermentation was carried out using a column reactor, in which 20 to 200 thin silicone tubes (0.33 mm in outer diameter) were packed to supply oxygen by permeation. The highest value of volumetric oxygen transfer coefficient determined by the sulfite oxidation method was 2,860 h^–1, which was comparable to that of a well agitated and aerated fermentor. The maximum production rate of acetic acid by the bacterial films of Acetobacter aceti M7 grown on the shell-side surface of the tubes was 38.0 g/lh at an acetic acid concentration of 44.5 g/l. This was 29 times that of a continuous culture using a jar fermentor.     

Genetic distinctness between two forms of Tetranychus urticae Koch (Acari: Tetranychidae) detected by electrophoresis

The genetic relatedness between the green and red forms of the two-spotted spider mite, Tetranychus urticae Koch, was analysed using an allozyme marker, MDH, detected by polyacrylamide gel electrophoresis. Cross experiments showed that each of the two forms had form-specific alleles for MDH. Furthermore, there was no overlapping in the alleles for MDH between the field populations of the two forms, suggesting that no gene flow would occur between them in the field.     

A novel mechanism for utilization of extracellular AMP in Vibrio parahaemolyticus

Vibrio parahaemolyticus could grow with AMP, ADP or ATP as the sole source of carbon. In the presence of Cl-, a membrane-bound Cl(-)-dependent 5'-nucleotidase seemed to hydrolyze the nucleotides extracellularly, and then the cells took up the resulting adenosine. In the absence of Cl-, although no significant dephosphorylation of the nucleotides occurred, the cells could still grow with AMP, but not with ADP or ATP. Moreover, in the presence of Cl-, Zn2+ inhibited the 5'-nucleotidase, and inhibited growth of the cells with ADP or ATP, but not with AMP, as the carbon source. V. parahaemolyticus was unable to grow with adenine or ribose 5-phosphate. These results suggested that the cells might have an AMP transport system. In fact, Na+ uptake was observed on addition of AMP to a cell suspension in the absence of Cl-, indicating Na+-AMP cotransport.     

Alternations in hepatic expression of fatty-acid metabolizing enzymes in ArKO mice and their reversal by the treatment with 17β-estradiol or a peroxisome proliferator

We generated aromatase gene knockout mice (ArKO mice) by targeting disruption of Cyp19, which encodes an enzyme responsible for conversion of androgens to estrogens. We found that ArKO males developed hepatic steatosis spontaneously with aging, indicating that the function of Cyp19 is required to maintain constitutive lipid metabolism in male mice. Plasma lipoprotein analysis using a gel permeation chromatography revealed that high density lipoprotein (HDL)-cholesterol levels were slightly higher in ArKO males than in wild-type males, whereas no other obvious alternations in the profiles were detected. Nevertheless, analysis of lipoprotein compositions by SDS-polyacrylamide gel electrophoresis demonstrated apparent reduction in the amounts of apolipoprotein E, functioning in receptor-mediated clearance of lipoproteins in the liver, in the IDL/LDL fraction of ArKO males as compared with that of wild-type males. Biochemical analysis on the ArKO livers revealed suppression of mRNA expression and activity of enzymes involved in fatty acid β-oxidation. The impairment was reversed to the wild-type levels by treatment with 17β-estradiol or bezafibrate, the latter is a synthetic peroxisome proliferator. These findings indicated a pivotal role of estrogen in supporting constitutive hepatic expression of genes involved in fatty acid β-oxidation and in maintaining lipid homeostasis.     

Inhibitory effects of echinoisoflavanone and sophoraisoflavanone D in Sophora chrysophylla SEEM on lipid peroxidation of mice brain homogenate by interaction of ferrous ion and hydrogen peroxide, in vitro

We present the results of an in vitro investigation of the inhibitory effects of echinoisoflavanone and sophoraisoflavanone D isolated from Sophora chrysophylla SEEM on lipid peroxidation of mice brain homogenate by interaction of ferrous ion and hydrogen peroxide, in vitro. They inhibited lipid peroxidation. The order of inhibitory effects of these isoflavanones and mannitol as a hydroxy radical scavenger was echinoisoflavanone > mannitol > sophoraisoflavanone D. The results suggest that some isoflavanones may be of use in cases where oxidative stress is present.     

SPR-based DNA Detection with Metal Nanoparticles

In this short review paper, we summarize some of our ideas to utilize gold nanoparticles for the enhancement of surface plasmon resonance signals on DNA microarray. The hybridization of target-DNA capped gold nanoparticles with probe DNA on surface provides ca. ten times stronger optical contrast compared with that of target-DNA molecules. Our simulation result based on the Maxwell-Garnet theory explains well our experimental data and proves a potential of metallic nanoparticles for the substantial sensitivity enhancements for biosensor application in DNA diagnostics and bio-affinity studies, which leads to the fabrication of high resolution DNA microarrays.     

Effects of Aluminum and pH on Root Growth and Cell Viability in Arabidopsis thaliana Strain Landsberg in Hydroponic Culture

Responses to aluminum and pH of root elongation in Arabidopsisthaliana strain Landsberg in hydroponic culture were examined.Incubation at pH 4.8 or addition of 1 µM A1C1₃ at pH 5.0severely inhibited elongation. However, there were differencesbetween treatments in the stainability of cells with fluoresceindiacetate and propidium iodide. (Received August 19, 1994; Accepted November 15, 1994)