Primary Culture of Identified Neurones From a Cnidarians

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Abstract
Several types of neurones were dissociated from the nerve-rings of the hydrozoan jellyfish Polyorchis penicillatus, using collagenase digestion preceded, and if necessary followed, by removal of external divalent cations. The neurones were cultured for up to 2 weeks in artificial sea water, on a mesogloeal substratum. One subset of large neurones, the swimming motor neurones (SMNs; soma approx. 20×50 μm), exhibited distinct morphological features in vitro, such as large size, wide processes, clear cytoplasm and membranous inclusions around the nucleus. These neurones retained their characteristic action potential shape in culture, with spikes measuring 50±11 mV (N=18) in peak amplitude and 37 ± 11 ms in duration. SMNs could be labelled in vivo with carboxyfluorescein or Lucifer Yellow, subsequently dissociated, and identified in vitro. Two subsets of small neurones were also identifiable. One exhibited electrophysiological similarities with B system neurones, known to be presynaptic to the SMNs in vivo, showing a burstlike pattern of spikes of short duration (5.4 ± 1.4 ms; N=6) and small amplitude (25 ± 7mV). Another subset of small neurones could be labelled with antiserum against the carboxy-terminal peptide moiety, Arg-Phe-amide. Biophysical and neurotransmitter studies at the level of the single identified hydrozoan neurone will be easier in isolated cell culture. This approach will avoid problems encountered in studying the semidissected nerve-ring preparation.