Neuromuscular development in Patellogastropoda (Mollusca: Gastropoda) and its importance for reconstructing ancestral gastropod bodyplan features

Abstract

Within Gastropoda, limpets (Patellogastropoda) are considered the most basal branching taxon and its representatives are thus crucial for research into evolutionary questions. Here, we describe the development of the neuromuscular system in Lottia cf. kogamogai. In trochophore larvae, first serotonin-like immunoreactivity (lir) appears in the apical organ and in the prototroch nerve ring. The arrangement and number of serotonin-lir cells in the apical organ (three flask-shaped, two round cells) are strikingly similar to those in putatively derived gastropods. First, FMRFamide-lir appears in veliger larvae in the Anlagen of the future adult nervous system including the cerebral and pedal ganglia. As in other gastropods, the larvae of this limpet show one main and one accessory retractor as well as a pedal retractor and a prototroch muscle ring. Of these, only the pedal retractor persists until after metamorphosis and is part of the adult shell musculature. We found a hitherto undescribed, paired muscle that inserts at the base of the foot and runs towards the base of the tentacles. An apical organ with flask-shaped cells, one main and one accessory retractor muscle is commonly found among gastropod larvae and thus might have been part of the last common ancestor.

Comparative transcriptomics enlarges the toolkit of known developmental genes in mollusks

“…150 km north of Vladivostok, Russian Federation). Embryos and adults of L. cf kogamogai were cultured and staged as previously described [118, 119]. Several hundred L. cf.…”

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

“…However, while numerous invertebrate taxa have been treated in detail, bivalves have so far been largely neglected. As such, within Mollusca, a solid database on neurogenesis exists for the gastropods (e.g., Croll and Voronezhskaya 1996 ; Dickinson et al 2000 ; Dickinson and Croll 2003 ; Croll 2006 ; Wollesen et al 2007 ; Page and Kempf 2009 ; Kristof and Klussmann-Kolb 2010 ; Kristof et al 2016 ), polyplacophorans (Friedrich et al 2002 ; Haszprunar et al 2002 ; Voronezhskaya et al 2002 ), and, to a far lesser degree, for aplacophorans (Redl et al 2014 ), scaphopods (Wanninger and Haszprunar 2003 ), cephalopods (Wollesen et al 2008 , 2010 ) and bivalves (Kreiling et al 2001 ; Voronezhskaya et al 2008 ).…”

“…Apart from the four longitudinal connectives, molluscan larvae typically exhibit an apical sensory organ as a shared feature with other lophotrochozoans (Wanninger and Wollesen 2015 ). Thereby, in gastropod (and the very few investigated bivalve) larvae, a single, median, serotonin-lir flask-shaped cell often appears first, which is subsequently flanked by two or three additional flask-shaped cells (Croll et al 1997 ; Kempf et al 1997 ; Marois and Carew 1997a , b ; Voronezhskaya et al 2008 ; Kristof et al 2016 ). 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 ).…”

A nemertean excitatory peptide/CCHamide regulates ciliary swimming in the larvae of Lineus longissimus

“…This stage called 'trochophora larva' is the name giving characteristic of the spiralian taxon that is referred to as Trochozoa (27)(28)(29)(30)(31). While antibodies against neuropeptides (usually FMRFamide) have been used widely to describe neuroanatomies of trochozoan larvae (32)(33)(34)(35)(36)(37)(38)(39)(40), there are comparably few studies that investigated the behavioral effect of neuropeptides in such larvae (41)(42)(43)(44)(45) and neither behavioral nor immunohistochemical studies investigated the EP/CCHamide in trochozoan larvae.…”