Echolocation sounds and hearing of the greater Japanese horseshoe bat (Rhinolophus ferrumequinum nippon)

Summary The relationship between the orientation sounds and hearing sensitivity in the greater Japanese horseshoe bat,Rhinolophus ferrumequinum nippon was studied.An orientation pulse consisted of a constant frequency (CF) component followed by a short downward frequency-modulated (FM) component. Sometimes, an initial upward FM component preceded the CF component. Duration of pulses was about 30 ms and the CF of resting pulses (RF) averaged 65.5 kHz. The best frequency (BF) at the lowest threshold in audiograms as measured by the pinna reflex averaged 66.1 kHz. Audiograms showed remarkable sharp cut-offs on both sides near the BF. The frequency difference between the BF and the RF was about 0.6 kHz, and the RF was always below the BF. The values of RF and BF were characteristically different from those of the European subspecies,Rhinolophus ferrumequinum ferrumequinum.Abbreviations BF best frequency - CF constant frequency - FM frequency modulated - RF resting frequency     

How to discriminate between vibration syndrome and local fatigue of motorcyclists

Motorcyclists who work in some offices sometimes complained of coldness, pain and numbness of upper limbs. We studied how to discriminate between vibration syndrome and local fatigue of the motorcyclists. Subjects are 42 motorcyclists of an office in Aichi prefecture. 25 of them held several letters in their left hand when they delivered the letters. They complained of coldness, pain and numbness in the left upper limbs more than in the right limbs (p less than 0.01). We think that it is the local fatigue rather than the disorder of vibration syndrome that causes such symptoms. So it is very important to recognize the existence of local fatigue in order to know how to discriminate between vibration syndrome and local fatigue of the motorcyclists.     

Studies on the Structure of Gluco-oligosaccharides Obtained from the Partial Acid Hydrolyzate of Sclerotia of Sclerotinia libertiana

The defatted sclerotia powder was partially hydrolyzed with dilute acid, and the material obtained was fractionated by carbon column chromatography, separated into two disaccharides, three trisaccharides and three tetrasaccharides, respectively. In these hydrolyzates α, α-trehalose, Iaminaribiose, and gentiobiose were identified.     

Quantitative structure-activity relationships of structurally similar odorless and odoriferous benzenoid musks

To reveal the difference of molecular property between structurallysimilar odorless and odoriferous musk compounds, 10 pairs ofbenzenoids (monocyclic-, dicyclic- and tricyclic-) were examined.Molecular structures of all compounds were optimized by MNDO(modified neglect of diatomic differential overlap) consideringconformation. Parameters effective in discriminating two groups,group A of 10 odorless compounds and group B of 10 musk odorcompounds, were searched from 34 candidate parameters by adaptiveleast squares. The best three parameters found were log P value(octanol/water partition coefficient), the longest side lengthof hexahedron circumscribing a molecule, and the parameter whichexpresses structural hindrance to the functional group whena molecule approaches the receptor site. The two groups of compoundswere completely discriminated using these three parameters.     

Density dependent growth of corneal endothelial cells cultured in vitro

Using the cornea of macaque monkey, we demonstrated the relationship between cell density and growth of endothelial cells in vitro. Corneal endothelial cells in a cell sheet grow most actively in regions with cell density of 1000 to 1800 cells/mm2, in explant cultures and cell sheets and in concentrated inocula dissociated cells. Cell morphology was well sustained in these cultures. Cells cultured at a higher cell density retained their potential to proliferate actively, showing clear contrast to cells cultured at a density lower than 200 cells/mm2. When dissociated cells were cultured at a low density and maintained for more than 4 weeks, they gradually lost their growth potential, altered into polymorphonuclear giant cells and eventually dedifferentiated. In addition, cells with no contact with each other did not express growth potential. Density dependent growth was confirmed by measuring the mitotic index against the cell density per square mm from the center to the peripheral regions in cultured explants. It is concluded that the growth pattern of corneal endothelial cells is closely related to cell density, and that growth of these cells might be regulated through intercellular communications.     

Molecular relationship between two types of phospholipase B from Penicillium notatum and reconstitution of active enzyme from its peptide fragments

Two types of phospholipase B of Penicillium notatum, the native type and the modified type that is thought to be generated by the introduction of some nicks into the native type of enzyme by the endogenous protease(s), were distinguished on a slab sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis under a nonreducing condition. The native form migrated with a rate corresponding to 95K Da, whereas the modified form migrated more slowly, corresponding to 106K Da, presumably because of its more extended conformation. That the "106K" protein was indeed a nicked product of the "95K" protein was confirmed by amino acid analysis, peptide mapping, N- and C-terminal sequence analyses, and immunoblotting. The peptide fragments (70K and 37K + 32K) comprising the modified protein were isolated by gel filtration in the presence of SDS and 2-mercaptoethanol (the 32K peptide was suggested to be a partial proteolytic product of the 37K peptide). When the "95K" protein was subjected to the same treatment under denaturing condition, it retained a low, but significant, enzymatic activity; in contrast, the separated peptide fragments did not show any significant activity. By a coincubation of these fragments, however, a restoration of enzymatic activity was observed through a reformation of the active complex, corresponding to the original modified protein. The enzymatic activity of this complex was further increased by a treatment with guanidine X HCl, followed by dialysis. The association of peptide fragments appears to occur through the formation of interpeptidal disulfide bonds.     

Sulfhydryl modification and activation of phenylalanine hydroxylase by dinitrophenyl alkyl disulfide

A new family of asymmetric thiol-disulfide exchange reagents, the dinitrophenyl alkyl disulfides (DNPSSR), was used to modify rat liver phenylalanine hydroxylase. The results indicate that the enzyme has two different types of reactive sulfhydryl (SH) residues per subunit. One SH residue was modified selectively by a DNPSSR having a neutral and hydrophilic alkyl group, and this modification was accompanied by appreciable activation of enzyme; the other SH residue was modified only by an anionic DNPSSR, and this modification did not result in activation. The catalytic properties of phenylalanine hydroxylase activated by DNPSSR were similar to those of the N-ethylmaleimide- (NEM-) modified enzyme, but the process of activation by DNPSSR was quite different from modification with NEM. An analysis of the reaction kinetics of the modification and of catalysis by the modified enzyme suggests that DNPSSR modification causes a change in the subunit interaction leading to a loss of the negative cooperativity normally seen with phenylalanine hydroxylase.     

Nitrile hydratase of Pseudomonas chlororaphis B23. Purification and characterization

Nitrile hydratase of Pseudomonas chlororaphis B23 was completely stabilized by the addition of 22 mM n-butyric acid. The enzyme was purified from extracts of methacrylamide-induced cells of P. chlororaphis B23 in eight steps. At the last step, the enzyme was crystallized by adding ammonium sulfate. The crystallized enzyme appeared to be homogeneous from analysis by polyacrylamide gel electrophoresis, analytical ultracentrifuge, and double diffusion in agarose. The enzyme has a molecular mass of about 100 kDa and consists of four subunits identical in molecular mass (approximately 25 kDa). The enzyme contained approximately 4 mol iron/mol enzyme. The concentrated solution of highly purified nitrile hydratase had a pronounced greyish green color and exhibited a broad absorption in visible range with a absorption maxima at 720 nm. A loss of enzyme activity occurred in parallel with the disappearance of the absorption in the visible range under a variety of conditions. The enzyme catalyzed stoichiometrically the hydration of nitrile to amide, and no formation of acid and ammonia were detected. The enzyme was active toward various aliphatic nitriles, particularly, nitriles with 3-6 carbon atoms, e.g. propionitrile, n-butyronitrile, acrylonitrile and cyclopropyl cyanide, served as the most suitable substrates.