Gb. Brumwell et Vj. Martin, ULTRASTRUCTURAL-LOCALIZATION OF RFAMIDE-LIKE PEPTIDES IN NEURONAL DENSE-CORED VESICLES OF A CNIDARIAN PLANULA LARVA, Invertebrate biology., 115(1), 1996, pp. 13-19
The location of Arg-Phe-amide (RFamide)-like peptides in dense-cored v
esicles in neurons of the planula larva of the marine hydrozoan Pennar
ia tiarella was shown using immunogold electron microscopy. Expression
of the peptide was detected as early as 16 h after fertilization. Gol
d-labeled dense-cored vesicles ranging from 80 nm to 140 nm in diamete
r were found in both cell bodies and neurites of ganglion cells (non-c
iliated bipolar and multipolar neurons found at the base of the ectode
rm just above the mesoglea) located in the aboral (anterior) and middl
e regions of the planulae. Within the neurites, the labeled dense-core
d vesicles were found in distinct clusters all along their lengths in
close association with the cell membranes, a distribution which sugges
ts that release of the peptide in planulae probably does not occur at
specialized synaptic sites. Labeled cells also contained unlabeled den
se-cored vesicles, unlabeled clear vesicles (60 nm to 100 nm in diamet
er), and unlabeled electron-dense droplets (100 nm to 240 nm in diamet
er). Localization of RFamide peptides to dense-cored vesicles of speci
fic neurons in early planulae is significant because of growing eviden
ce on the role of these substances in morphogenesis.