engleski

Expression of NF, GFAP, and dendrin in the brain of small-spotted catshark Scyliorhinus canicula L.

In the present study we reported the expression of neurofilaments (NFs) and glial fibrillary acidic protein (GFAP) and for the first time the expression of dendrin in the brain of small- spotted catshark Scyliorhinus canicula L. Small-spotted catshark is a well-known model species of cartilaginous fishes. Its developing telencephalon shows more similarities to those of mammals than to those of bony fishes, amphibians, and birds. Neurofilaments (NFs) are members of the intermediate filament protein family which are essential for the formation of the neuronal cytoskeleton. GFAP is expressed by numerous central nervous system (CNS) cell types, including astrocytes and ependymal cells during development. Dendrin, a proline-rich protein known as a neuron and renal protein, has an important role in synaptic plasticity and as a postsynaptic component has a significant impact in modulating synaptic cytoskeleton. The tissues of sectioned forebrain, midbrain, and hindbrain of ten specimens of Scyliorhinus canicula L. fresh-caught in the Adriatic Sea were studied using histochemical and immunofluorescence techniques. Hematoxylin-eosin and Mallory staining were used to identify the histological structure of these brain parts. These sections were observed using a Leica DM 3000 LED microscope (Leica Microsystems, Germany). For immunofluorescence, the sections were incubated overnight with primary antibodies according to their own protocols followed by incubation with suitable secondary antibodies for one hour. The nuclei were stained with DAPI. The images were captured with epifluorescence microscope Olympus BX51 (Olympus Corporation, Tokyo, Japan). The present study has shown that morphological and histochemical composition of the forebrain and midbrain have many similarities. Most of the neuronal tissue are neuronal and glial cells bodies surrounded by neuropil. In the cerebellum, three layers could be distinguished: the most superficial layer, the middle one called the Purkinje cells layer and the deepest granular one. The other part of the hindbrain, the medulla oblongata, histologically resembles the granular cerebellum layer. NF, GFAP, and dendrin in the catshark's brain are highly expressed in all parts of the brain except in the medulla oblongata where the expression pattern was weaker for all investigated proteins. Morphological and histochemical analysis of the small-spotted catshark’s brain confirmed the great potential of this cartilaginous fish not only as a model for evo- devo studies but as a model in the adult stage that shows more similarities to mammals than it was thought, with the special emphasis on the distribution of dendrin in the non-mammalian brain for the first time.

neurofilaments, GFAP, dendrin, immunofluorescence, small-spotted catshark

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