DNA-based identification of fish species implicated in Puffer fish poisoning

A method for identification of fish species using three different mitochondrial DNA regions, 16S rRNA, cytochrome b and cytochrome c gene fragments, was investigated. The combined use of all three regions enabled reliable species identification in not only raw fish, but also dried, seasoned and boiled fish, products. Furthermore, the method was applicable even to vomitus from a patient involved in a puffer fish poisoning incident. However, further improvement is necessary to discriminate between closely related species such as Takifugu rubripes and T. chinensis, because they showed close similarity in the nucleotide sequences in the three gene fragments analyzed in this study.     

Swelling of hydrophilic polymers. II

The swelling of five types of Sephadex that are either nonionic (G) or possess one of four different ionic groups [sodium carboxymethyl (CM), sodium sulfopropyl (SP), diethyl-aminoethyl chloride (DEAE), diethyl - (2-hydroxypropyl) aminoethyl chloride (QAE)] in the same skeleton of the molecule has been studied by picture analysis and by calorimetry. Inducing dissociation of the ionic group in the polymer skeleton increased the water swelling. By the addition of sodium chloride, the maximum swelling volume of nonionic Sephadex was only slightly decreased. However, that of ionic polymers was considerably decreased. The variation of the apparent first-order rate constant of the swelling and that of the maximum swelling volume show the same tendency. The maximum heats of swelling were 93.2 ± 7.1 J g^?1 for G, 128.8 ± 9.1 J g^?1 for CM, 92.3 ± 8.0 J g^?1 for SP, 68.8 ± 10.5 J g^?1 for DEAE, and 67.0 ± 7.2 J g^?1 for QAE and did not depend on the concentration of sodium chloride. From the results obtained, we conclude that the nonionic Sephadex swells only by hydration but that ionic Sephadexes swell mainly by the osmotic pressure due to the counterions of the ionic groups and that the swelling ratio is not dependent on the kinds of ions but on the ionic concentration. Most of the water in the gels of ionic Sephadexes is free water that does not interact with the Sephadexes. © 1993 John Wiley & Sons, Inc.     

NMR and fluorescence studies of the self-association behavior of an amphiphilic polyanion bearing hydrocarbon and fluorocarbon hydrophobes

The association behavior of the terpolymers of sodium 2-acrylamido-2-methylpropanesulfonate (NaAMPS), N-dodecylmethacrylamide (DodMAm), and N-(2-(perfluorooctyl)ethyl)methacrylamide (PFOEMAm) (A/H(x)/F(y)) and their reference copolymers of NaAMPS and PFOEMAm (A/F(y)) was characterized using ¹⁹F and ¹H NMR, steady state fluorescence, and dynamic light scattering techniques in water (or D₂O) containing 0.1 M NaCl. The terpolymers formed micelle-like aggregates where hydrophobic microdomains are formed by hydrophobic associations among the perfluorooctylethyl (PFOE) and dodecyl (Dod) groups, the PFOE group exhibiting a stronger tendency for interpolymer association than the Dod groups. A careful analysis of the characterization data led to a conclusion that the hydrophobic microdomain formed from the terpolymer is microscopically phase separated into the fluorocarbon phase and hydrocarbon phase.     

Developmental Formation of the GABAergic and Glycinergic Networks in the Mouse Spinal Cord

Gamma-aminobutyric acid (GABA) and glycine act as inhibitory neurotransmitters. Three types of inhibitory neurons and terminals, GABAergic, GABA/glycine coreleasing, and glycinergic, are orchestrated in the spinal cord neural circuits and play critical roles in regulating pain, locomotive movement, and respiratory rhythms. In this study, we first describe GABAergic and glycinergic transmission and inhibitory networks, consisting of three types of terminals in the mature mouse spinal cord. Second, we describe the developmental formation of GABAergic and glycinergic networks, with a specific focus on the differentiation of neurons, formation of synapses, maturation of removal systems, and changes in their action. GABAergic and glycinergic neurons are derived from the same domains of the ventricular zone. Initially, GABAergic neurons are differentiated, and their axons form synapses. Some of these neurons remain GABAergic in lamina I and II. Many GABAergic neurons convert to a coreleasing state. The coreleasing neurons and terminals remain in the dorsal horn, whereas many ultimately become glycinergic in the ventral horn. During the development of terminals and the transformation from radial glia to astrocytes, GABA and glycine receptor subunit compositions markedly change, removal systems mature, and GABAergic and glycinergic action shifts from excitatory to inhibitory.