The presence and location of small cardioactive-like peptides in larvae of Crassostrea virginica

Abstract

We examined the presence and location of small cardioactive peptide (SCP)‐like neuropeptides in both the central and peripheral nervous systems of D‐hinge, newly eyed, and pediveliger larvae of Crassostrea virginica. Results indicate that SCP‐like substances are present early in development (D‐hinge larvae), and that presence in the central and peripheral nervous systems increases as the larva develops toward metamorphic competence (pediveliger larvae). In addition, in newly eyed and pediveliger larvae, SCP‐like labeling is found in a varying number of neurons within all central ganglia, with the possible exception of the accessory ganglia. Varicose labeling of axons is also documented within the ganglia, commissures, and connectives, as well as in peripheral nerves. Peripheral tissues innervated by axons exhibiting SCP‐like immunoreactivity include the velum, foot, esophagus, mantle, and various musculatures. As indicated by the location of SCP‐like labeling in various organs and tissues, it is likely that these neuropeptides modulate muscle contraction or ciliary beating in molluscan larvae such as those of C. virginica.

Inter- and intraspecific plasticity in distribution patterns of immunoreactive compounds in actinotroch larvae of Phoronida (Lophotrochozoa)

“…; Ohsuga and Kurokawa ; Willows et al. ; Kempf and Page ; Settembrini and Villar ; Kanda and Minakata ; Hochberg ; Ellis and Kempf ; Hochberg and Atherton ).…”

“…The staining results in a weak signal where the apical organ, the marginal neurite bundle of the preoral hood, the innervation of the tentacles and the telotroch neurites are the most prominent neural structures. Although it is hypothesized that small cardioactive peptide B plays a role in the regulation of the heart beat rate, muscle modulation and ciliary activity in molluscan larva, little is known concerning potential additional functions of this neuropeptide (Ellis and Kempf ). The positive signal in phoronids and a wide range of other invertebrates such as molluscs, annelids, gastrotrichs, rotifers and arthropods corroborates the assumption that this compound was also present in the protostome groundplan (cf.…”

“…; Willows et al. ; Ellis and Kempf ), cephalopods (Kanda and Minakata ), annelids (Evans and Calabrese ) and arthropods (Settembrini and Villar ). In larval and adult molluscs, it is expressed in the central and peripheral nervous system, and in adult arthropods, the distribution of this neuropeptide is concentrated in the brain and the subesophagal ganglion, while in adult annelids, it is mainly expressed in the segmental ganglia (Evans and Calabrese ; Perry et al.…”

“…In larval and adult molluscs, it is expressed in the central and peripheral nervous system, and in adult arthropods, the distribution of this neuropeptide is concentrated in the brain and the subesophagal ganglion, while in adult annelids, it is mainly expressed in the segmental ganglia (Evans and Calabrese ; Perry et al. ; Settembrini and Villar ; Ellis and Kempf ). Taken together, our work increases the morphological database concerning the larval neuroanatomy of Phoronida and contributes to a better understanding of the evolution of the lophotrochozoan nervous system.…”

Towards a ground pattern reconstruction of bivalve nervous systems: neurogenesis in the zebra mussel Dreissena polymorpha

“…In scaphopods, the apical organ comprises four serotonin-lir flask-shaped cells (Wanninger and Haszprunar 2003 ), while eight to ten cells are found in the apical organ of polyplacophorans (Friedrich et al 2002 ; Voronezhskaya et al 2002 ) and neomeniomorph aplacophorans (although in the latter not all show serotonin-like immunoreactivity) (Redl et al 2014 ). Other identified neuroactive compounds in gastropod apical organs include leu-enkephalin (Dickinson and Croll 2003 ), catecholamines (Croll 2006 ), and various neuropeptides (FMRFamide and small cardioactive-like peptide) (Voronezhskaya et al 2008 ; Ellis and Kempf 2011a , b ). The emerging cerebral commissure and the anlagen of the cerebro-visceral connectives form at the base of the apical organ, while the organ itself degenerates during or prior to metamorphosis (Marois and Carew 1997a ; Dickinson and Croll 2003 ; Wanninger and Wollesen 2015 ).…”