Fluorescence and flow dichroism of F-actin-epsilon-ADP; the orientation of the admine plane relative to the long axis of F-actin.

The excitation polarization spectrum of epsilon-ADP bound to F-actin shows that two absorption dipoles at 260 nm and 340 nm are oriented in different directions relative to the emission dipole. On the other hand, the linear dichroism of F-actin-epsilon-ADP gives that the dichroic ratio of the bound epsilon-ADP is approximately constant (about-0.5) in the wavelength region form 250 to 350nm. Furthermore, the fluorescence polarization of epsilon-ADP bound to F-actin which is oriented in the field of flow shows that the emission dipole is nearly perpendicular to the long axis of F-actin. From these observations we conclude that the adenine plane of the bound nucleotide is almost perpendicular to the long axis of F-actin.     

Distribution and Recent Reduction of Gelidium Beds in Toyama Bay, Japan

The distribution and recent reduction of Gelidium beds, i.e. mat-like beds dominated by the agarophyte G. elegans Kützing in Toyama Bay (Sea of Japan), in which 95% of the coastline is protected artificially, are reported. Gelidium beds were common in shallow waters (usually < 10 m deep); most of the large beds (> 1 ha) were restricted to the inner coasts of the bay. In calm and eutrophic areas, however, G. elegans was heavily colonized by epiphytes. In the last decade, two beds were buried in situ and beds in their vicinity were damaged by the stagnation of coastal water and/or sedimentation by silts which accompanied land reclamation. At the other two beds monitored since 1988, Gelidium declined a few times but most prominently in 1998, when episodic long summer rain was recorded. This is the first report, not only on the current status of Gelidium beds other than for the central Pacific Coast of Honshu in Japan, but also concerning reduction of the beds caused by both anthropogenic and natural events.     

Presentation of Various Tactile Sensations Using Micro-Needle Electrotactile Display

Tactile displays provoke tactile sensations by artificially stimulating tactile receptors. While many types of tactile displays have been developed, electrotactile displays that exploit electric stimulation can be designed to be thin, light, flexible and thus, wearable. However, the high voltages required to stimulate tactile receptors and limited varieties of possible sensations pose problems. In our previous work, we developed an electrotactile display using a micro-needle electrode array that can drastically reduce the required voltage by penetrating through the high-impedance stratum corneum painlessly, but displaying various tactile sensations was still a challenge. In this work, we demonstrate presentation of tactile sensation of different roughness to the subjects, which is enabled by the arrangement of the electrodes; the needle electrodes are on the fingertip and the ground electrode is on the fingernail. With this arrangement, the display can stimulate the tactile receptors that are located not only in the shallow regions of the finger but also those in the deep regions. It was experimentally revealed that the required voltage was further reduced compared to previous devices and that the roughness presented by the display was controlled by the pulse frequency and the switching time, or the stimulation flow rate. The proposed electrotactile display is readily applicable as a new wearable haptic device for advanced information communication technology.     

β-Hydroxy-α-ketobutyric acid in Drosophila melanogaster,with reference to biosynthesis of drosopterins

A substance designated as compound D, which reacts spontaneously with 7,8-dihydropterin to give drosopterins, is found in Drosophila melanogaster. The compound was partially purified from the extract of flies by column chromatography and identified as β-hydroxy-α-ketobutyric acid by analysis of its 2,4-dinitrophenylhydrazone, mass spectrometry and reactivity with 7,8-dihydropterin. A highly significant correlation (r = 0.969, p < 0.001) was found between the amounts of the compound and drosopterins in the eye-pigment mutants of Drosophila. Changes of the compound during development of flies were also closely related to those of drosopterins. Based on these observations, a role of the compound in biosynthesis of drosopterins has been discussed.     

Thioredoxin-related Protein 32 (TRP32) Specifically Reduces Oxidized Phosphatase of Regenerating Liver (PRL)

PRL family constitutes a unique class of phosphatases associated with metastasis. The phosphatase activity of PRL has been reported to be important for promoting metastasis, and it is inactivated by reversible oxidation of its catalytic cysteine. Here, we show that TRP32 specifically reduces PRL. Reduction of oxidized PRL in cells is inhibited by 2,4-dinitro-1-chlorobenzene, an inhibitor of TRX reductase. In vitro assays for the reduction of PRL show that only TRP32 can potently reduce oxidized PRL, whereas other TRX-related proteins linked to TRX reductase show little or no reducing activity. Indeed, TRP32 knockdown significantly prolongs the H₂O₂-induced oxidation of PRL. Binding analyses reveal that the unique C-terminal domain of TRP32 is required and sufficient for its direct interaction with PRL. These results suggest that TRP32 maintains the reduced state of PRL and thus regulates the biological function of PRL.     

Purification and properties of D-glyceraldehyde-3-phosphate dehydrogenase from an extreme thermophile, Thermus thermophilus strain HB 8.

1. D-Glyceraldehyde-3-phosphate dehydrogenase from an extreme thermophile, T. thermophilus strain HB8, was purified and crystallized. 2. The enzyme was found to possess remarkable heat stability, being slowly inactivated at 90 degrees C. 3. Basic kinetic constants and pH profile are reported. The enzyme was activated 25-fold by 90 mM NH4Cl, and also by ethanol up to 5-fold at 30 degrees C. 4. The enzyme was found to be far more resistant to urea or sodium dodecylsulfate than the rabbit enzyme. 5. The enzyme was shown to be a tetramer of molecular weight 130000--135000. Amino acid composition analysis revealed no unusual features. Circular dichroic spectra suggested that the contents of the ordered structure of the thermophile enzyme are similar to those of the rabbit enzyme. 6. The other catalytic properties of the thermophile enzyme are discussed in comparison with those of the enzymes from other sources.     

cDNA cloning of bradykinin-potentiating peptides-C-type natriuretic peptide precursor, and characterization of the novel peptide Leu3-blomhotin from the venom of Agkistrodon blomhoffi.

A cDNA clone, 1.8 kb long, was isolated from a venom gland cDNA library of Agkistrodon blomhoffi that encodes a large plurifunctional precursor composed of 263 amino-acid residues. Nucleotide sequence analysis of this clone revealed that sequences which code for blomhotin and a novel peptide Leu3-blomhotin are located in the N-terminal region of the precursor polypeptide, followed by four tandemly aligned sequences which code for three types of bradykinin-potentiating peptide. In the C-terminal region, the sequence for the C-type natriuretic peptide was located along with a preceding processing signal. The deduced amino-acid sequences for the four bradykinin-potentiating peptides coincided exactly with previously known sequences for potentiator B, potentiator C and potentiator E. The actual Leu3-blomhotin peptide was subsequently isolated from the venom of A. blomhoffi and characterized. Leu3-blomhotin possesses contractile activity in isolated rat stomach fundus smooth muscle in the same manner as blomhotin. Furthermore, it was shown that blomhotin and Leu3-blomhotin retained activity to inhibit the angiotensin-converting enzyme.