Elsevier Science B.V. Acta Medica Okayama 0006-8993 961 2 2003 A Periaxonal Net in the Zebrafish Central Nervous System 179 189 EN Hiroshi Nakayasu Noriko Arata We produced a monoclonal antibody, named A20, which specifically recognizes a 35 kDa protein and stains myelinated axons in zebrafish brain. The A20 antigen is located at the outside of the myelin layer of large axons, and comprises a fine meshwork composed of thin unit fibers about 1–2 μm in length and about 100–200 nm in thickness. The unit fibers form pentagonal and hexagonal structures, which further polymerize into an envelope structure on the axons. The A20 monoclonal antibody did not stain neuronal cell bodies nor synapses. Instead, the distribution of the A20 antigen was along axons, practically coincident with the distribution of myelin basic protein. The monoclonal antibody stained only axons in the central nervous system (CNS), and not the extracellular matrix surrounding Schwann cells. These results suggest that this antigenic meshwork (which we call the periaxonal net) is synthesized by oligodendrocytes. During the development of the zebrafish brain, the periaxonal net appeared after the formation of myelin on the axons. The periaxonal net developed first at the brain stem, then gradually appeared at the caudal end of the spinal cord. The thickness of the periaxonal net around the Mauthner axon changed during development. Although the thickness of the Mauthner axon continues to grow throughout life, the thickness of periaxonal net stopped growing at 6 months after fertilization. No potential conflict of interest relevant to this article was reported.

Acta Medica Okayama 1129 1 2007 Distribution of a brain-specific extracellular matrix protein in developing and adult zebrafish 53 62 EN Takahiro Kanai Taketoshi Kajimoto Hiroshi Nakayasu <p>A monoclonal antibody (IgG) that recognizes a 53-kDa zebrafishnext brain protein was isolated and used to characterize the distribution of this protein in zebrafish.next (1) The antigen was found only in the brain and not in any other tissues such as muscle, dermis and cartilage. Within the brain, the antibody recognized extracellular matrix (ECM) outside neuronal cells. (2) Digestion by hyaluronidase released the antigen from brain tissue, and the monoclonal antibody staining was also decreased by the digestion by hyaluronidase. (3) The pattern of antigen distribution is not perineuronal, as the density of the antigen at the periphery of the cells was practically identical to that of the empty intercellular spaces. Therefore, this monoclonal antibody does not recognize the perineuronal glycocortex. (4) The antigen is distributed only in limited areas of the brain, namely in the periphery of the forebrain, the hypothalamus, the optic tectum, the interpeduncular nucleus, the cerebellum and the ventricular rim of the medulla. In the optic tectum, the antibody strongly stained the most superficial layer, and in the cerebellum, it stained the molecular but not the granular layer. These patterns of distribution are very different from those of other typical brain ECM proteins and suggest that this protein may play quite distinct roles in brain development and maintenance.</p> No potential conflict of interest relevant to this article was reported.