GLUTAMINE-SYNTHETASE IS A GLIAL-SPECIFIC MARKER IN THE OLFACTORY REGIONS OF THE LOBSTER (PANULIRUS-ARGUS) NERVOUS-SYSTEM

Glutamine synthetase (GS) has been qualified as a very specific marker of astroglial-type neuroglia in vertebrate neural tissues. In this pa per we have begun to examine the possibility that glial localization o f GS could be a ubiquitous characteristic of complex nervous systems. To this end we have used immunohistochemistry to localize GS-like immu noreactivity in the olfactory regions of the complex nervous system of the arthropod, the spiny lobster Panulirus argus. We describe a novel method for affinity isolation of antibodies from crude serum. Using t his approach we purified GS-specific antibodies to chick retina GS and used these to analyze the lobster brain and the primary olfactory org an. Western blots showed that the lobster brain contains an immunoreac tive peptide with nearly the same molecular mass as that of chick reti na GS. Northern blot analyses of mRNA and enzymatic activity assays al so confirm that the lobster brain produces GS. Immunohistochemical sta ining of sectioned lobster olfactory lobes and sensory sensilla showed strong reactivity in specific cells. Comparison of the GS immunostain ing pattern with that for FMRFamide, a well characterized marker of ne urons in invertebrate neural tissues, it became clear that GS is indee d glial-specific in lobster neural tissues as it is in vertebrates. Th ese results suggest that the compartmentalization of GS in non-neurona l cells is either an early step in neural evolution or is an obligate and fundamental characteristic of complex neural systems composed of b oth neurons and neuroglia. (C) 1997 Wiley-Liss, Inc.