Exploration of Chemosensory Ionotropic Receptors in Cephalopods: the IR25 gene is expressed in the Olfactory Organs, Suckers, and Fins of Sepia officinalis

International audienceWhile they are mostly renowned for their visual capacities, cephalopods are also good at olfaction for prey, predator and conspecific detection. The olfactory organs and olfactory cells are well described but olfactory receptors -genes and proteins- are still undescribed in cephalopods. We conducted a broad phylogenetic analysis of the ionotropic glutamate receptor family in molluscs (iGluR), especially to identify IR members (Ionotropic Receptors), a variant subfamily whose involvement in chemosensory functions has been shown in most studied protostomes. A total of 312 iGluRs sequences (including 111 IRs) from gastropods, bivalves and cephalopods were identified and annotated. One orthologue of the gene coding for the chemosensory IR25 co-receptor has been found in Sepia officinalis (Soff-IR25). We searched for Soff-IR25 expression at the cellular level by in situ hybridization in whole embryos at late stages before hatching. Expression was observed in the olfactory organs, which strongly validates the chemosensory function of this receptor in cephalopods. Soff-IR25 was also detected in the developing suckers, which suggests that the unique « taste by touch » behavior that cephalopods execute with their arms and suckers share features with olfaction. Finally, Soff-IR25 positive cells were unexpectedly found in fins, the two posterior appendages of cephalopods, mostly involved in locomotory functions. This result opens new avenues of investigation to confirm fins as additional chemosensory organs in cephalopods

Shh and Pax6 have unconventional expression patterns in embryonic morphogenesis in Sepia officinalis (Cephalopoda).

International audienceCephalopods show a very complex nervous system, particularly derived when compared to other molluscs. In vertebrates, the setting up of the nervous system depends on genes such as Shh and Pax6. In this paper we assess Shh and Pax6 expression patterns during Sepia officinalis development by whole-mount in situ hybridization. In vertebrates, Shh has been shown to indirectly inhibit Pax6. This seems to be the case in cephalopods as the expression patterns of these genes do not overlap during S. officinalis development. Pax6 is expressed in the optic region and brain and Shh in gut structures, as already seen in vertebrates and Drosophila. Thus, both genes show expression in analogous structures in vertebrates. Surprisingly, they also exhibit unconventional expressions such as in gills for Pax6 and ganglia borders for Shh. They are also expressed in many cephalopods' derived characters among molluscs as in arm suckers for Pax6 and beak producing tissues, nuchal organ and neural cord of the arms for Shh. This new data supports the fact that molecular control patterns have evolved with the appearance of morphological novelties in cephalopods as shown in this new model, S. officinalis

FaRP cell distribution in the developing CNS suggests the involvement of FaRPs in all parts of the chromatophore control pathway in Sepia officinalis (Cephalopoda)

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Identification of the Endangered Pink-to-Red Stylaster Corals by Raman Spectroscopy

International audienceAll corals within the Stylasteridae family (including the Stylaster genus) are listed in Appendix II of CITES; this means they are protected and their trade requires an export permit, unlike corals from the Corallium genus, which include most pink-to-red corals used in jewelry. Raman scattering demonstrates that corals from the Stylaster genus contain carotenoid pigments (polyenic pigments substituted with methyl groups), whereas those from the Corallium genus are colored by unmethylated polyenic pigments. Additionally, Stylaster corals are made of aragonite, whereas those from Corallium are composed of calcite. Through Raman scattering analysis, the fully protected Stylaster pink-to-red corals may be distinguished from this other type of gem coral

Identification of the Endangered Pink-to-Red Stylaster Corals by Raman Spectroscopy

International audienceAll corals within the Stylasteridae family (including the Stylaster genus) are listed in Appendix II of CITES; this means they are protected and their trade requires an export permit, unlike corals from the Corallium genus, which include most pink-to-red corals used in jewelry. Raman scattering demonstrates that corals from the Stylaster genus contain carotenoid pigments (polyenic pigments substituted with methyl groups), whereas those from the Corallium genus are colored by unmethylated polyenic pigments. Additionally, Stylaster corals are made of aragonite, whereas those from Corallium are composed of calcite. Through Raman scattering analysis, the fully protected Stylaster pink-to-red corals may be distinguished from this other type of gem coral

Identification of the Endangered Pink-to-Red Stylaster Corals by Raman Spectroscopy

International audienceAll corals within the Stylasteridae family (including the Stylaster genus) are listed in Appendix II of CITES; this means they are protected and their trade requires an export permit, unlike corals from the Corallium genus, which include most pink-to-red corals used in jewelry. Raman scattering demonstrates that corals from the Stylaster genus contain carotenoid pigments (polyenic pigments substituted with methyl groups), whereas those from the Corallium genus are colored by unmethylated polyenic pigments. Additionally, Stylaster corals are made of aragonite, whereas those from Corallium are composed of calcite. Through Raman scattering analysis, the fully protected Stylaster pink-to-red corals may be distinguished from this other type of gem coral

Looking for immediate early genes as neuronal activation markers in the cephalopod mollusc Sepia officinalis

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The Pax gene family: Highlights from cephalopods

International audiencePax genes play important roles in Metazoan development. Their evolution has been extensively studied but Lophotrochozoa are usually omitted. We addressed the question of Pax paralog diversity in Lophotrochozoa by a thorough review of available databases. The existence of six Pax families (Pax1/9, Pax2/5/8, Pax3/7, Pax4/6, Paxβ, PoxNeuro) was confirmed and the lophotrochozoan Paxβ subfamily was further characterized. Contrary to the pattern reported in chordates, the Pax2/5/8 family is devoid of homeodomain in Lophotro-chozoa. Expression patterns of the three main pax classes (pax2/5/8, pax3/7, pax4/6) during Sepia officinalis development showed that Pax roles taken as ancestral and common in metazoans are modified in S. officinalis, most likely due to either the morphological specifici-ties of cephalopods or to their direct development. Some expected expression patterns were missing (e.g. pax6 in the developing retina), and some expressions in unexpected tissues have been found (e.g. pax2/5/8 in dermal tissue and in gills). This study underlines the diversity and functional plasticity of Pax genes and illustrates the difficulty of using probable gene homology as strict indicator of homology between biological structures