Hitomi Hirose

Phylogenetic analysis of intestinal bacteria and their adhesive capability in relation to the intestinal mucus of carp

Aims:  The aims of the present study are to characterize the intestinal microbial community displaying a high‐adhesive capability in fish, and to evaluate the relationship between mucosal adhesion of intestinal bacteria and fish health and disease.

Characterization of Japanese eel immunoglobulin M and its level in serum.

Japanese eel immunoglobulin M (IgM) was purified from the sera of Anguilla japonica immunized with Edwardsiella tarda FPU 347 and characterized. Analysis of the purified IgM on sodium dodecyl sulfate-polyacrylamide gels (SDS-PAGE) under reducing and non-reducing conditions revealed that the eel IgM was a tetrameric protein with a molecular weight of 790,000; it contained an equimolar heavy chain and light chain with molecular weights of 72,000 and 25,000, respectively. While the N-terminal sequence of the heavy chain, VELTQPGSMVLKPGQSLTI, showed similarity to the variable regions of those of teleost fishes Igs, the N-terminal sequence of the light chain, DIVLTQSPAVQSVQLGDT, was similar to the variable regions of chondrostei and mammalian kappa chains. Lectin-binding assays showed that the binding of concanavalin A (Con A) to the Japanese eel IgM heavy chain was competitively inhibited by D-mannose and could be abolished by alpha-mannosidase treatment indicating the presence on the heavy chain of oligosaccharides, whose terminal were a bound mannoses. The average IgM concentration in the sera of the healthy eels was 3.4 mg ml(-1); it amounted to 10.3% of the total serum protein.

Epidermal response of the Japanese eel to environmental stress

Nonspecific responses of Japanese eels to environmental stress were monitored by assaying various lytic activities in eel epidermal extract. In fish maintained at 10 and 30 °C for up to 10 days, epidermal proteolytic activities due to serine protease and aminopeptidase and hemolytic activity varied within a 2-fold value range. Other proteolytic activities, due to cathepsins B and L, in the fish at 30 °C increased for up to 8 days and were 3.4 and 2.9-fold over those in fish maintained at 10 °C, respectively. This was accompanied by a 3.0-fold increase in bacteriolytic activity. Other forms of stress were exerted on the fishes by immersing them in a suspension of Flavobacterium columnare or giving them intraperitoneal injections of Edwardsiella tarda over 72 h. Although serine protease and aminopeptidase activities and hemolytic activity in the fishes exposed to F. columnare changed marginally, and were similar to those in the control fish, cathepsins B and L activities in the infected fishes increased more than 1.5-fold over their initial values over a 48 h period, along with a 4.5-fold increase in bacteriolytic activity. No marked change was detected in any of the lytic activities of the fishes exposed to E. tarda. These findings indicate that epidermal cathepsins B and L probably participate in bacteriolysis associated with Japanese eel skin and that their activities are elicited by environmental stimuli and may be an important nonspecific response of eels. Abbreviations: Cbz – carbobenzoxy; MCA – 4-methylcoumaryl-7-amide.

Scuticociliata infection in the weedy sea dragon Phyllopteryx taeniolatus

The weedy sea dragon Phyllopteryx taeniolatus at an aquarium in Kanagawa Prefecture were found infected by protozoan ciliate, 2001. The infected fish in particular, showed sloughing of the epidermis. Fish with intense infections showed sloughing of the dorsal fin, depigmentation of skin, anal distension and accumulation of ascitic fluid in the body cavity. In biopsies, ciliates were detected only in fresh mounts of abdominal dropsy and in the mucus on the body surface. Histopathological studies revealed ciliates mainly infected the dermis, and induced extensive detachment of the epidermis from the skin. Based on the arrangement and shape of the buccal structure and the number of somatic ciliature, ciliates isolated from the fishes belonged to the order Scuticociliatida. We discuss the major factors that bring about the death of weedy sea dragons.

OmpA is an adhesion factor of Aeromonas veronii, an optimistic pathogen that habituates in carp intestinal tract.

Aims:  In the present study, we focused on one of the Aeromonas veronii isolates that exhibited marked adhesion onto carp intestine and studied its membrane‐associated proteins for their possible involvement in mucosal adhesion.

Fluorescence localization of epidermal cathepsins L and B in the Japanese eel

Histochemical localization of proteolytic activities in the dorsal epidermis of Japanese eel was demonstrated by fluorescent microscopy utilizing 4-methoxy-2-naphthylamide (4M

Cytochrome P450 induction and gonadal status alteration in common carp (Cyprinus carpio) associated with the discharge of dioxin contaminated effluent to the Hikiji River, Kanagawa Prefecture, Japan

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MMP-9 is expressed during wound healing in Japanese flounder skin

NA) derivatives as substrates and 5-nitrosalicylaldehyde as a trapping agent. Carbobenzoxy-L-phenylalanyl-L-arginyl-4M

Two new species of hexabothriid monogeneans from the ginzame Chimaera phantasma and shortspine spurdog Squalus mitsukurii

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Phylogeography of the Japanese eight-barbel loach Lefua echigonia from the Yamagata area of the Tohoku district, Japan

NA (Cbz-Phe-Arg-4M