Abstract
Cells immunoreactive to an antiserum specifically directed against vertebrate alpha-Neo-endorphin (alpha-NE) were detected in the internal wall of anterior and posterior suckers of the rhynchobdellid leech Theromyzon tessulatum. These cells have morphological and ultrastructural characteristics close to the "releasing gland cells" of adhesive organs. The epitope recognized by anti-alpha-NE was contained in granules having a diameter of 0.2-0.3 microm. Previous works involving the brain of this leech demonstrate the existence of approximately 14 neurons immunoreactive to the anti-alpha-NE. Following an extensive purification including high pressure gel permeation and reversed-phase high performance liquid chromatography, epitopes contained in both suckers and central nervous system were isolated. Purity of the isolated peptides was controlled by capillary electrophoresis. Their sequences were determined by a combination of automated Edman degradation, electrospray mass spectrometry measurement, and coelution experiments in reversed-phase high performance liquid chromatography with synthetic alpha-NE. The results demonstrate that epitopes recognized by the anti-alpha-NE in the suckers and the central nervous system are identical to vertebrate alpha-NE (YGGFLRKYPK). This finding constitutes the first biochemical characterization of a prodynorphin-derived peptide in invertebrates. Moreover the isolation of this peptide in the annelida establishes the very ancient phylogenetic origin of alpha-NE as well as its conservation in evolution.
Highlights
If these three genes encoding opioid peptides are related (Gubler, 1987), one of the central questions is in what order did these genes evolve from a hypothetical ancestral gene? In this context research on different opioid peptides in invertebrates is essential (Stefano, 1991)
The present study demonstrates that to the peptide ␣-NE isolated from the CNS and suckers of the leech T. tessulatum is structurally identical with the one identified in vertebrates (YGGFLRKYPK)
The present study shows that ␣-NE immunoreactive cells in T. tessulatum suckers have morphological and ultrastructural characteristics close to the “releasing gland cells” of adhesive organs of the Branchiobdellids (Farnesi et al, 1981; Hogg et al, 1983; Gelder and Rowe, 1988; Weigl, 1994)
Summary
If these three genes encoding opioid peptides are related (Gubler, 1987), one of the central questions is in what order did these genes evolve from a hypothetical ancestral gene? In this context research on different opioid peptides in invertebrates is essential (Stefano, 1991). A pepsystem are identical to vertebrate ␣-NE (YGGFL- tide derived from POMC maturation in vertebrates, ␥-MSH, RKYPK) This finding constitutes the first biochemical has been characterized in the leech Theromyzon tessulacharacterization of a prodynorphin-derived peptide in invertebrates. Given this amount of information in invertebrates concerning opioid peptides, little is known about ␣-NE in these animals. Processing of the prodynorphin yields a number of bioactive peptides including leucine-enkephalin, Neo-endorphins (␣ and ), and dynorphins (A and B) (Patey and Rossier, 1986) Among these peptides, ␣-Neo-endorphin (␣-NE) has been isolated from all vertebrates phyla
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