FMRFGene Expression in the Nervous System of the SquidDoryteuthis Pealei* Hatchling

Abstract

FMRFamide is a neuropeptide that is widely distributed in invertebrates and known to be involved in many physiological functions. Previously we noted marked differences in expression of the fmrf gene in the stellate ganglion of Doryteuthis pealei* compared to the central nervous system. In this study we aimed to examen the brain systems of Doryteuthis pealei* for the presence and distribution of fmrfexpressing cells and fiber networks. Late squid embryos and hatchlings were examined by in situ hybridization and immunohistochemistry in whole mounts and tissue sections. All central lobes contained limited numbers of scattered neurons expressing fmrf, but the FMRFamide-containing fiber systems were abundant and extensive, mostly present in the neuropil of lobes. Main clusters of neurons were located in the magnocellular and chromatophore lobes of the posterior subesophageal mass (PSM), and in dorsal aspects of the basal lobe (BL). Dense FMRFamide-immunoreactive fibers were particularly seen in the optic lobe (OL), medial and posterior supraesophageal masses (MSM and SPM) often with a commissural organization. The data show that the central lobes of Doryteuthis pealei hatchlings have a matured FMRFamide system organized in a limited number of centers, but with widely distributed efferents. This suggests that FMRFamide neurons are already functionally engaged in the late embryo. The localization indicates that control of chromatophores and fin movement are amongst these functions.

Cell type diversity in a developing octopus brain

“…We could identify known cell types in the dataset such as dopaminergic (DOP), GABAergic (GABA), serotonergic (SERT) and peptidergic (PEP-fmrfa+) neuronal subtypes. A large body of work has been done on the localization of FMRFamide (fmrfa) synthesizing neurons in different cephalopods 17,[36][37][38][39] . In this study, we identified three different fmrfa precursor genes which are differentially expressed between cell types (Fig.…”

Transcriptome-wide selection and validation of a solid set of reference genes for gene expression studies in the cephalopod mollusk Octopus vulgaris

“…In cephalopods, the study of the molecular machinery occurring in these processes is still limited. Few studies of cuttlefish ( Agin et al, 2000 , 2001 , 2003 ; Focareta et al, 2014 ; Focareta and Cole, 2016 ; Bian et al, 2018 ), squid ( Giuditta et al, 2002 ; Kimbell and McFall-Ngai, 2003 ; Burbach et al, 2019 ), and octopus ( Zarrella, 2011 ; Zarrella et al, 2015 ; van Giesen et al, 2020 ; see also Prado-Álvarez et al, 2022 ) have been based on an exiguous number of specific candidate molecules involved in given functions or biological aspects of cephalopod plasticity.…”