Article

Identification of novel neuropeptides in the ventral nerve cord ganglia and their targets in an annelid worm, Eisenia fetida

Division of Neurobiology Department of Biology II and Graduate School of Systemic Neurosciences, Ludwig-Maximilians-Universitat Munich, D-82152 Martinsried, Germany.
The Journal of Comparative Neurology (Impact Factor: 3.51). 06/2009; 514(6):spc1. DOI: 10.1002/cne.22071
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ABSTRACT Periviscerokinins (PVKs) and pyrokinins (PKs) are neuropeptides known in several arthropod species. Sequence homology of these peptides with the molluscan small cardioactive peptides reveals that the occurrence of PVKs and PKs is not restricted to arthropods. Our study focuses on the biochemical and immunocytochemical identification of neuropeptides with sequence homology to PVKs and PKs in the central and peripheral nervous system of the earthworm Eisenia fetida. By means of affinity chromatography, nanoflow liquid chromatography, and high accuracy mass spectrometry, six peptides, SPFPR(L/I)amide, APFPR( L/I)amide, SPLPR( L/I)amide, SFVR( L/I)amide, AFVR( L/I)amide, and SPAFVR( L/I)amide, were identified in the central nervous system with the common-XR( L/I)amide C-terminal sequence. The exact anatomical position of 13 labeled XR( I/L)amide expressing neuron groups and numerous peptide-containing fibers were determined by means of immunocytochemistry and confocal laser scanning microscopy in whole-mount preparations of ventral nerve cord ganglia. The majority of the stained neurons were interneurons with processes joining the distinct fine-fibered polysegmental tracts in the central neuropil. Some stained fibers were seen running in each segmental nerve that innervated metanephridia and body wall. Distinct groups of neurosecretory cells characterized by small round soma and short processes were also identified. Based on immunoelectron microscopy six different types of labeled cells were described showing morphological heterogeneity of earthworm peptides containing elements. Our findings confirm that the sequence of the identified earthworm neuropeptides homologous to the insect PVKs and PKs suggesting that these peptides are phylogenetically conservative molecules and are expressed in sister-groups of animals such as annelids, mollusks, and insects. J. Comp. Neurol. 514:415-432, 2009. (c) 2009 Wiley-Liss, Inc.

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    • "The unpurified antiserum recognizes peptides with the C-terminal sequence PRXamide and is known to react with periviscerokinins and with pyrokinins (Eckert et al., 2002). It has been used to specifically label these substances in a variety of insect species (D. melanogaster: Wegener et al., 2004; Nezara viridula: Predel et al., 2006; Manduca sexta: Neupert et al., 2009); Schistocerca gregaria: Herbert et al., 2010; Acyrthosiphon pisum: Kollmann et al., 2011a), in the chelicerate Ixodes ricinus (Neupert et al., 2005), and in the clitellate annelid Eisenia fetida (Herbert et al., 2009). "
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