D/L-isomerization of a particular amino-acid residue of bioactive peptides is a rare, but attractive phenomenon. NdWFa (Asn-D-Trp-Phe-NH₂) is a D-Trp-containing neuropeptide, originally identified in an opistobranch gastropod, Aplysia kurodai. In this animal, the major source of NdWFa is neurons located in the right-upper quadrant of the abdominal ganglion. NdWFa has a potent cardioexcitatry action on the Aplysia heart with the threshold concentration around 10^-10 M. It also induces contraction of blood vessels of the animal. NdWFa has high resistance to digestion by peptidase, although it is inactivated by deamidase activity in nervous tissue of the animal. The nuclear magnetic resonance analysis demonstrated a unique structure of NdWFa, which is not observed when the D-Trp is replaced to L-Trp. This structure seems to be essential for the bioactivity on the Aplysia heart and resistance to peptidase digestion of the peptide. In this review, we will describe the identification, localization, physiological activities and precursor gene of NdWFa to exemplify the D-amino acid containing neuropeptide in gastropods. We will also refer to the D/L-isomerase that converts L-amino acid to D-amino acid in the post-translational modification of bioactive peptides.

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Fear and anxiety are indispensable defense reactions for survival of animals, and have been relatively well investigated among various emotions. To reveal neural mechanisms underlying fear and anxiety in fish, it is essential to employ robust and quantitative method to measure the level of fear and anxiety. Recently, in addition to classical comparative psychological tests, some behavioral tests incorporating ethological viewpoint for evaluating fish fear/anxiety have been introduced. Typical behavioral tests for measuring anxiety level include the novel environment test and light/dark preference test. Classical fear conditioning and avoidance learning can be used to examine the conditioned fear that is subjected to quantitative analysis. Innate fear response can be reproducibly evoked by exposing the fish to alarm substance. Visual and/or chemical contacts with sympatric predators also evoke fear responses in some fishes. These days, using such behavioral tests, many behavioral neuroscientific and biomedical researches have been conducted to investigate neural substrates of fear and anxiety in fishes. However, only a few species have been utilized for such researches while a great number of fish species have been adaptively radiated to various aquatic environments. Fishes showing intriguing fear/anxiety behavior might be awaiting to be discovered.

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In this article, we introduce to construct and use a database system in the laboratory for research resource management and application. The combination of XAMPP package and XOOPS Cube is providing a web based data management environment easily. As an example of usage of database contents, it was shown that a method for register of neuron morphologies on the standard brain coordinate is documented. It was conducted by using free software, ITK-SNAP and Fiji, so this protocol would be applied for the integration of morphological data obtained by individuals.

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