Neuronal development in larval mussel Mytilus trossulus (Mollusca: Bivalvia)

Abstract

Although our understanding of neuronal development in Trochozoa has progressed substantially in recent years, relatively little attention has been paid to the bivalve molluscs in this regard. In the present study, the development of FMRFamide-, serotonin-and catecholamine-containing cells in the mussel, Mytilus trossulus, was examined using immunocytochemical and histoXuorescent techniques. Neurogenesis starts during the trochophore stage at the apical extreme with the appearance of one FMRFamide-like immunoreactive (lir) and one serotonin-lir sensory cell. Later, Wve FMRFamide-lir and Wve serotonin-lir apical sensory cells appear, and their basal Wbres form an apical neuropil. Fibres of two lateral FMRFamide-lir apical cells grow posteriorly and at the time that they reach the developing foot, the Wrst FMRFamide-lir neurons of the pedal ganglia also appear. Subsequently, FMRFamide-lir Wbres grow further posteriorly and reach the caudal region where neurons of the developing visceral ganglia then begin to appear. In contrast, the Wve apical serotonin-lir neurons do not appear to project outside the apical neuropil until the late veliger stage. Catecholamine-containing cells are Wrst detected in the veliger stage where they appear above the oesophagus, and subsequently in the velum, foot, and posterior regions. Though neural development in M. trossulus partly resembles that of polyplacophorans in the appearance of the early FMRFamidergic elements, and of scaphopods in the appearance of the early serotonergic elements, the scenario of neural development in M. trossulus diVers considerably from that of other Trochozoa (bivalves, gastropods, polyplacophorans, scaphopods and polychaetes) studied to date.

Assessment of housekeeping genes as internal references in quantitative expression analysis during early development of oyster

“…Current studies on molluscan development include many aspects such as cell fate mapping (Dictus and Damen, 1997;Hejnol et al, 2007), axis determination (Koop et al, 2007), organogenesis (Voronezhskaya et al, 2008;Wang et al, 2008) and shell formation (Nederbragt et al, 2002;Kin et al, 2009). Studies on these processes are essential to understand the development and evolution of mollusks.…”

How to make a protostome

“…in the polyplacoporan Ischnochiton (Voronezhskaya et al 2002), the gastropods Ilyanassa and Crepidula (Dickinson and Croll 2003;Hejnol et al 2007) (see Fig. 8) and the bivalve Mytilus (Voronezhskaya et al 2008). Its function is poorly studied, but it is involved in settling in some species (Hadfield et al 2000).…”

Structure-Function of Serotonin in Bivalve Molluscs

“…It has been seen that the first 5-HT-IR neurons appearing within the nervous system correspond to the location of the CG and apical ganglion (AG) during the late trochophore stage: 30-32 h postfertilization in blue mussel [136], 24 h postfertilization in surf clam [137], and 27 h postfertilization in the Bay mussel (Mytilus trossulus) [138]. Kreiling et al [137] reported As animals lost the ability to synthesize tryptophan, there possess developed biological mechanisms through which animals obtain tryptophan from their diets.…”