(full paper is archived in the Miller Library)
Title: GFAP Immunoreactivity in octopus nervous system before and after injury
Student Author(s): Liu, Taylor I.
Faculty Advisor(s): Gilly, William
Location: Final Papers Biology 175H
Date: June 1991
Abstract: Astrogliosis following injury to the mammalian central nervous system is accompanied by increased synthesis of glial fibrillary acidic protein (GFAP) and the lack of regeneration. In order to extend studies of GFAP expression in relation to injury in taxa of higher regenerative capacity, we chose Octopus rubescens as a model system. We used a polyclonal anti-human GFAP in conjunction with immunoblotting and immunohistochemistry techniques applied to optic lobes of the brain and to peripheral axial nerve cords in the arms. Animals were also studied before and after lesion to the axial nerves that contain ganglionic regions of neuronal and glial somata. In uninjured Octopus, Western blots with both tissue sources revealed a single protein band (140kD). Pre-absorption of the antibody with purified human GFAP eliminated this band, which is larger than the 48-51 kD protein found in vertebrates. Immunostaining of fixed and sectioned material from axial nerve cords showed that anti-GFAP preferentially stained cellular regions. This pattern is distinct from that produced by anti-neurofilament, which stained primarily neuropil and axons. Studies were also carried out following injury, immunoblotting revealed an increased level of the 140 kD band. Experiments on other cephalopods were also carried out. In uninjured Sepia officianalis, Sepioteuthis lessoniana, and Loligo opalescens, the 140 kD band was not detected by Western blots with optic lobe proteins. This product was obtained, however, with axial nerve material from Sepia. These results (i) indicate the presence of a GFAP-like protein in the nervous system of cephalopods, (ii) show that increased protein levels accompany injurey in the peripheral nerve cords in Octopus, and (iii) suggest that the protein may be associated with glial cells.