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.     

Enhancing effects of transition metals on the salt taste responses of single fibers of the frog glossopharyngeal nerve: specificity of and similarities among Ca2+, Mg2+ and Na+ taste responses

Fibers of the frog glossopharyngeal nerve (water fibers) thatare sensitive to water also respond to CaCl₂, MgCl₂ and NaCl.In the present study, interaction among cations (Ca²⁺, Mg²⁺and Na⁺) on taste cell membrane in frogs was studied using transitionmetals (NiCl₂, CoCl₂ and MnCl₂), which themselves are barelyeffective in producing neural response at concentrations below5 mM. Unitary discharges from single water fibers were recordedfrom fungiform papillae with suction electrode. Transition metalions (0.05–5.0 mM) had exclusively enhancing effects onthe responses to 50 mM Ca²⁺, 100 mM Mg²⁺ and 500 mM Na⁺. Theeffects of transition metal ions were always reversible. Therank order of effectiveness of transition metals at 1 mM inthe enhancement of the responses to 50 mM CaCl₂, 100 mM MgCl₂and 500 mM NaCl was NiCl₂ > CoCl² > MnCl₂. The concentrationof transition metal ions effective to enhance salt responsewas almost the same among Ca²⁺, Mg²⁺ and Na⁺ responses. Theresults suggest that a common mechanism is involved in the enhancementof Ca²⁺, Mg²⁺ and Na⁺ taste responses. The enhanced Mg²⁺ responseand the enhanced Na⁺ response were greatly inhibited by theaddition of Ca²⁺ ions, and the enhanced Ca²⁺ response was inhibitedby the addition of Mg²⁺ or Na⁺ ions, suggesting that competitiveantagonism occurs between Ca²⁺ and Mg²⁺ ions and between Ca²⁺and Na⁺ ions in the presence of Ni²⁺ ions. Ni²⁺ ions had a dualeffect on the Ca²⁺ response induced by low concentration (0.1mM) of CaCl₂: enhancement at lower concentrations (0.02–0.1mM) of NiCl₂ and inhibition at higher concentrations (0.5–5mM)of NiCl₂. The present results suggest that transition metalions do not affect the receptor-antagonist complex, but affectonly the receptor-agonist complex.     

Anaerobic biodegradability of polyvinyl alcohol

Summary Biodegradability of polyvinyl alcohol (PVA) under anaerobic conditions was demonstrated using anaerobic river sediments and anaerobically treated activated sludge from a sewage treatment plant. PVA having molecular weights of 2000 and 14000 was over 60% biodegraded as determined by TOC.     

Screening for glycosylphosphatidylinositol (GPI)-dependent cell wall proteins in Saccharomyces cerevisiae

Open reading frames in the genome of Saccharomyces cerevisiae were screened for potential glycosylphosphatidylinositol (GPI)-attached proteins. The identification of putative GPI-attached proteins was based on three criteria: the presence of a GPI-attachment signal sequence, a signal sequence for secretion and a serine- or threonine-rich sequence. In all, 53 ORFs met these three criteria and 38 were further analyzed as follows. The sequence encoding the 40 C-terminal amino acids of each was fused with the structural gene for a reporter protein consisting of a secretion signal, α-galactosidase and a hemagglutinin (HA) epitope, and examined for the ability to become incorporated into the cell wall. On this basis, 14 of fusion proteins were classified as GPI-dependent cell wall proteins because cells expressing these fusion proteins: (i) had high levels of α-galactosidase activity on their surface; (ii) released significant amounts of the fusion proteins from the membrane on treatment with phosphatidylinositol-specific phospholipase C (PI-PLC); and (iii) released fusion proteins from the cell wall following treatment with laminarinase. Of the 14 identified putative GPI-dependent cell wall proteins, 12 had novel ORFs adjacent to their GPI-attachment signal sequence. Amino acid sequence alignment of the C-terminal sequences of the 12 ORFs, together with those of known cell wall proteins, reveals some sequence similarities among them. Received: 1 September 1997 / Accepted: 20 November 1997     

Regulation of the Expression of the Myosin Heavy Chain (MYH) Gene myh14 in Zebrafish Development

Marine Biotechnology - The human sarcomeric myosin heavy chain gene MYH14 contains an intronic microRNA, miR-499. Our previous studies demonstrated divergent genomic organization and expression...     

Study on the Correlation of Chemical Structure and Ovicidal Activities of 2-Bromoethylthiobenzenes

2-Bromoethylthiobenzenes were toxic to the eggs of Tetranychus telarius (L.) depending on the permeability and the reactivity of the compounds. It was suggested by the means of ρ-σ-π analysis that the reactivity depends on the electron-donating power of the sulfur atom to the site of action or the carbon atom of carbon-bromine linkage.