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Dvorzhak A, Brecht M, Schmitz D. Social play behavior is driven by glycine-dependent mechanisms. Curr Biol 2024; 34:3654-3664.e6. [PMID: 39053464 DOI: 10.1016/j.cub.2024.06.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/19/2024] [Accepted: 06/27/2024] [Indexed: 07/27/2024]
Abstract
Social play is pervasive in juvenile mammals, yet it is poorly understood in terms of its underlying brain mechanisms. Specifically, we do not know why young animals are most playful and why most adults cease to social play. Here, we analyze the synaptic mechanisms underlying social play. We found that blocking the rat periaqueductal gray (PAG) interfered with social play. Furthermore, an age-related decrease of neural firing in the PAG is associated with a decrease in synaptic release of glycine. Most importantly, modulation of glycine concentration-apparently acting on the glycinergic binding site of the N-methyl-D-aspartate (NMDA) receptor-not only strongly modulates social play but can also reverse the age-related decline in social play. In conclusion, we demonstrate that social play critically depends on the neurotransmitter glycine within the PAG.
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Affiliation(s)
- Anton Dvorzhak
- Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Neuroscience Research Center, 10117 Berlin, Germany
| | - Michael Brecht
- Humboldt-Universität zu Berlin, Bernstein Center for Computational Neuroscience, Philippstr. 13, 10115 Berlin, Germany; Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, NeuroCure Cluster of Excellence, 10117 Berlin, Germany
| | - Dietmar Schmitz
- Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Neuroscience Research Center, 10117 Berlin, Germany; Humboldt-Universität zu Berlin, Bernstein Center for Computational Neuroscience, Philippstr. 13, 10115 Berlin, Germany; Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, NeuroCure Cluster of Excellence, 10117 Berlin, Germany; German Center for Neurodegenerative Diseases (DZNE), 10117 Berlin, Germany; Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Einstein Center for Neuroscience, 10117 Berlin, Germany; Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle-Straße 10, 13125 Berlin, Germany.
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2
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Kwon KM, Pak JH, Jeon CJ. Immunocytochemical localization of the AMPA glutamate receptor subtype GluR2/3 in the squid optic lobe. Acta Histochem 2022; 124:151941. [PMID: 35963117 DOI: 10.1016/j.acthis.2022.151941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/03/2022] [Accepted: 08/03/2022] [Indexed: 11/17/2022]
Abstract
As a major excitatory neurotransmitter in the cephalopod visual system, glutamate signaling is facilitated by ionotropic receptors, such as α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR). In cephalopods with large and well-developed brains, the optic lobes (OL) mainly process visual inputs and are involved in learning and memory. Although the presence of AMPAR in squid OL has been reported, the organization of specific AMPAR-containing neurons remains unknown. This study aimed to investigate the immunocytochemical localization of the AMPA glutamate receptor subtype 2/3-immunoreactive (GluR2/3-IR) neurons in the OL of Pacific flying squid (Tordarodes pacificus). Morphologically diverse GluR2/3-IR neurons were predominantly located in the tangential zone of the medulla. Medium-to-large GluR2/3-IR neurons were also detected. The distribution patterns and cell morphologies of calcium-binding protein (CBP)-IR neurons, specifically calbindin-D28K (CB)-, calretinin (CR)-, and parvalbumin (PV)-IR neurons, were similar to those of GluR2/3-IR neurons. However, two-color immunofluorescence revealed that GluR2/3-IR neurons did not colocalize with the CBP-IR neurons. Furthermore, the specific localizations and diverse types of GluR2/3-IR neurons that do not express CB, CR, or PV in squid OL were determined. These findings further contribute to the existing data on glutamatergic visual systems and provide new insights for understanding the visual processing mechanisms in cephalopods.
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Affiliation(s)
- Kyung-Min Kwon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jae-Hong Pak
- Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Chang-Jin Jeon
- Department of Biology, School of Life Sciences, BK21 FOUR KNU Creative BioResearch Group, College of Natural Sciences, Brain Science and Engineering Institute, Kyungpook National University, Daegu 41566, Republic of Korea; Research Institute for Dok-do and Ulleung-do Island, Department of Biology, School of Life Sciences, Kyungpook National University, Daegu 41566, Republic of Korea.
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3
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Stern-Mentch N, Winter G, Belenky M, Moroz L, Hochner B. Neurotransmission and neuromodulation systems in the learning and memory network of Octopus vulgaris. J Morphol 2022; 283:557-584. [PMID: 35107842 PMCID: PMC9303212 DOI: 10.1002/jmor.21459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/26/2022] [Accepted: 01/29/2022] [Indexed: 11/15/2022]
Abstract
The vertical lobe (VL) in the octopus brain plays an essential role in its sophisticated learning and memory. Early anatomical studies suggested that the VL is organized in a “fan‐out fan‐in” connectivity matrix comprising only three morphologically identified neuron types; input axons from the median superior frontal lobe (MSFL) innervating en passant millions of small amacrine interneurons (AMs), which converge sharply onto large VL output neurons (LNs). Recent physiological studies confirmed the feedforward excitatory connectivity; a glutamatergic synapse at the first MSFL‐to‐AM synaptic layer and a cholinergic AM‐to‐LNs synapse. MSFL‐to‐AMs synapses show a robust hippocampal‐like activity‐dependent long‐term potentiation (LTP) of transmitter release. 5‐HT, octopamine, dopamine and nitric oxide modulate short‐ and long‐term VL synaptic plasticity. Here, we present a comprehensive histolabeling study to better characterize the neural elements in the VL. We generally confirmed glutamatergic MSFLs and cholinergic AMs. Intense labeling for NOS activity in the AMs neurites were in‐line with the NO‐dependent presynaptic LTP mechanism at the MSFL‐to‐AM synapse. New discoveries here reveal more heterogeneity of the VL neurons than previously thought. GABAergic AMs suggest a subpopulation of inhibitory interneurons in the first input layer. Clear γ‐amino butyric acid labeling in the cell bodies of LNs supported an inhibitory VL output, yet the LNs co‐expressed FMRFamide‐like neuropeptides, suggesting an additional neuromodulatory role of the VL output. Furthermore, a group of LNs was glutamatergic. A new cluster of cells organized as a “deep nucleus” showed rich catecholaminergic labeling and may play a role in intrinsic neuromodulation. In‐situ hybridization and immunolabeling allowed characterization and localization of a rich array of neuropeptides and neuromodulators, likely involved in reward/punishment signals. This analysis of the fast transmission system, together with the newly found cellular elements, help integrate behavioral, physiological, pharmacological and connectome findings into a more comprehensive understanding of an efficient learning and memory network.
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Affiliation(s)
- Naama Stern-Mentch
- Department of Neurobiology, Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel
| | - Gabriela Winter
- Department of Neuroscience and McKnight Brain Institute, and Whitney Laboratory for Marine Bioscience, University of Florida, Gainesville, Florida, USA.,Ocean Genome Atlas Project, San Francisco, USA
| | - Michael Belenky
- Department of Neurobiology, Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel
| | - Leonid Moroz
- Department of Neuroscience and McKnight Brain Institute, and Whitney Laboratory for Marine Bioscience, University of Florida, Gainesville, Florida, USA
| | - Binyamin Hochner
- Department of Neurobiology, Silberman Institute of Life Sciences, Hebrew University, Jerusalem, Israel
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Moroz LL, Nikitin MA, Poličar PG, Kohn AB, Romanova DY. Evolution of glutamatergic signaling and synapses. Neuropharmacology 2021; 199:108740. [PMID: 34343611 DOI: 10.1016/j.neuropharm.2021.108740] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/13/2022]
Abstract
Glutamate (Glu) is the primary excitatory transmitter in the mammalian brain. But, we know little about the evolutionary history of this adaptation, including the selection of l-glutamate as a signaling molecule in the first place. Here, we used comparative metabolomics and genomic data to reconstruct the genealogy of glutamatergic signaling. The origin of Glu-mediated communications might be traced to primordial nitrogen and carbon metabolic pathways. The versatile chemistry of L-Glu placed this molecule at the crossroad of cellular biochemistry as one of the most abundant metabolites. From there, innovations multiplied. Many stress factors or injuries could increase extracellular glutamate concentration, which led to the development of modular molecular systems for its rapid sensing in bacteria and archaea. More than 20 evolutionarily distinct families of ionotropic glutamate receptors (iGluRs) have been identified in eukaryotes. The domain compositions of iGluRs correlate with the origins of multicellularity in eukaryotes. Although L-Glu was recruited as a neuro-muscular transmitter in the early-branching metazoans, it was predominantly a non-neuronal messenger, with a possibility that glutamatergic synapses evolved more than once. Furthermore, the molecular secretory complexity of glutamatergic synapses in invertebrates (e.g., Aplysia) can exceed their vertebrate counterparts. Comparative genomics also revealed 15+ subfamilies of iGluRs across Metazoa. However, most of this ancestral diversity had been lost in the vertebrate lineage, preserving AMPA, Kainate, Delta, and NMDA receptors. The widespread expansion of glutamate synapses in the cortical areas might be associated with the enhanced metabolic demands of the complex brain and compartmentalization of Glu signaling within modular neuronal ensembles.
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Affiliation(s)
- Leonid L Moroz
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA; Departments of Neuroscience and McKnight Brain Institute, University of Florida, Gainesville, FL, 32610, USA.
| | - Mikhail A Nikitin
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119991, Russia; Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127994, Russia
| | - Pavlin G Poličar
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA; Faculty of Computer and Information Science, University of Ljubljana, SI-1000, Ljubljana, Slovenia
| | - Andrea B Kohn
- Whitney Laboratory for Marine Biosciences, University of Florida, St. Augustine, FL, 32080, USA
| | - Daria Y Romanova
- Cellular Neurobiology of Learning Lab, Institute of Higher Nervous Activity and Neurophysiology, Moscow, 117485, Russia.
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Andouche A, Valera S, Baratte S. Exploration of chemosensory ionotropic receptors in cephalopods: the IR25 gene is expressed in the olfactory organs, suckers, and fins of Sepia officinalis. Chem Senses 2021; 46:6412677. [PMID: 34718445 DOI: 10.1093/chemse/bjab047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
While 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 mollusks (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.
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Affiliation(s)
- Aude Andouche
- Laboratoire de Biologie des Organismes et Ecosystemes Aquatiques (BOREA). MNHN, CNRS, SU, UCN, UA, 55 Rue Buffon, Paris, France
| | - Stéphane Valera
- Laboratoire de Biologie des Organismes et Ecosystemes Aquatiques (BOREA). MNHN, CNRS, SU, UCN, UA, 55 Rue Buffon, Paris, France
| | - Sébastien Baratte
- Laboratoire de Biologie des Organismes et Ecosystemes Aquatiques (BOREA). MNHN, CNRS, SU, UCN, UA, 55 Rue Buffon, Paris, France.,Sorbonne Université, Paris, France
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6
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Sykes AV, Almansa E, Ponte G, Cooke GM, Andrews PLR. Can Cephalopods Vomit? Hypothesis Based on a Review of Circumstantial Evidence and Preliminary Experimental Observations. Front Physiol 2020; 11:765. [PMID: 32848811 PMCID: PMC7396502 DOI: 10.3389/fphys.2020.00765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 06/11/2020] [Indexed: 11/13/2022] Open
Abstract
In representative species of all vertebrate classes, the oral ejection of upper digestive tract contents by vomiting or regurgitation is used to void food contaminated with toxins or containing indigestible material not voidable in the feces. Vomiting or regurgitation has been reported in a number of invertebrate marine species (Exaiptasia diaphana, Cancer productus, and Pleurobranchaea californica), prompting consideration of whether cephalopods have this capability. This "hypothesis and theory" paper reviews four lines of supporting evidence: (1) the mollusk P. californica sharing some digestive tract morphological and innervation similarities with Octopus vulgaris is able to vomit or regurgitate with the mechanisms well characterized, providing an example of motor program switching; (2) a rationale for vomiting or regurgitation in cephalopods based upon the potential requirement to void indigestible material, which may cause damage and ejection of toxin contaminated food; (3) anecdotal reports (including from the literature) of vomiting- or regurgitation-like behavior in several species of cephalopod (Sepia officinalis, Sepioteuthis sepioidea, O. vulgaris, and Enteroctopus dofleini); and (4) anatomical and physiological studies indicating that ejection of gastric/crop contents via the buccal cavity is a theoretical possibility by retroperistalsis in the upper digestive tract (esophagus, crop, and stomach). We have not identified any publications refuting our hypothesis, so a balanced review is not possible. Overall, the evidence presented is circumstantial, so experiments adapting current methodology (e.g., research community survey, in vitro studies of motility, and analysis of indigestible gut contents and feces) are described to obtain additional evidence to either support or refute our hypothesis. We recognize the possibility that further research may not support the hypothesis; therefore, we consider how cephalopods may protect themselves against ingestion of toxic food by external chemodetection prior to ingestion and digestive gland detoxification post-ingestion. Reviewing the evidence for the hypothesis has identified a number of gaps in knowledge of the anatomy (e.g., the presence of sphincters) and physiology (e.g., the fate of indigestible food residues, pH of digestive secretions, sensory innervation, and digestive gland detoxification mechanisms) of the digestive tract as well as a paucity of recent studies on the role of epithelial chemoreceptors in prey identification and food intake.
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Affiliation(s)
- António V Sykes
- CCMAR, Centro de Ciências do Mar do Algarve, Universidade do Algarve, Faro, Portugal
| | - Eduardo Almansa
- Department of Aquaculture, Instituto Español de Oceanografía, Centro Oceanográfico de Canarias, Santa Cruz de Tenerife, Spain
| | - Giovanna Ponte
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
| | - Gavan M Cooke
- Department of Life Sciences, Anglia Ruskin University, Cambridge, United Kingdom
| | - Paul L R Andrews
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Naples, Italy
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Robertson RM, Dawson-Scully KD, Andrew RD. Neural shutdown under stress: an evolutionary perspective on spreading depolarization. J Neurophysiol 2020; 123:885-895. [PMID: 32023142 PMCID: PMC7099469 DOI: 10.1152/jn.00724.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/13/2020] [Accepted: 01/14/2020] [Indexed: 11/22/2022] Open
Abstract
Neural function depends on maintaining cellular membrane potentials as the basis for electrical signaling. Yet, in mammals and insects, neuronal and glial membrane potentials can reversibly depolarize to zero, shutting down neural function by the process of spreading depolarization (SD) that collapses the ion gradients across membranes. SD is not evident in all metazoan taxa with centralized nervous systems. We consider the occurrence and similarities of SD in different animals and suggest that it is an emergent property of nervous systems that have evolved to control complex behaviors requiring energetically expensive, rapid information processing in a tightly regulated extracellular environment. Whether SD is beneficial or not in mammals remains an open question. However, in insects, it is associated with the response to harsh environments and may provide an energetic advantage that improves the chances of survival. The remarkable similarity of SD in diverse taxa supports a model systems approach to understanding the mechanistic underpinning of human neuropathology associated with migraine, stroke, and traumatic brain injury.
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Affiliation(s)
- R Meldrum Robertson
- Department of Biology and Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
| | - Ken D Dawson-Scully
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida
| | - R David Andrew
- Department of Biomedical and Molecular Sciences and Centre for Neuroscience Studies, Queen's University, Kingston, Ontario, Canada
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Scaros AT, Andouche A, Baratte S, Croll RP. Histamine and histidine decarboxylase in the olfactory system and brain of the common cuttlefish Sepia officinalis (Linnaeus, 1758). J Comp Neurol 2019; 528:1095-1112. [PMID: 31721188 DOI: 10.1002/cne.24809] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/30/2019] [Accepted: 10/30/2019] [Indexed: 02/05/2023]
Abstract
Cephalopods are radically different from any other invertebrate. Their molluscan heritage, innovative nervous system, and specialized behaviors create a unique blend of characteristics that are sometimes reminiscent of vertebrate features. For example, despite differences in the organization and development of their nervous systems, both vertebrates and cephalopods use many of the same neurotransmitters. One neurotransmitter, histamine (HA), has been well studied in both vertebrates and invertebrates, including molluscs. While HA was previously suggested to be present in the cephalopod central nervous system (CNS), Scaros, Croll, and Baratte only recently described the localization of HA in the olfactory system of the cuttlefish Sepia officinalis. Here, we describe the location of HA using an anti-HA antibody and a probe for histidine decarboxylase (HDC), a synthetic enzyme for HA. We extended previous descriptions of HA in the olfactory organ, nerve, and lobe, and describe HDC staining in the same regions. We found HDC-positive cell populations throughout the CNS, including the optic gland and the peduncle, optic, dorso-lateral, basal, subvertical, frontal, magnocellular, and buccal lobes. The distribution of HA in the olfactory system of S. officinalis is similar to the presence of HA in the chemosensory organs of gastropods but is different than the sensory systems in vertebrates or arthropods. However, HA's widespread abundance throughout the rest of the CNS of Sepia is a similarity shared with gastropods, vertebrates, and arthropods. Its widespread use with differing functions across Animalia provokes questions regarding the evolutionary history and adaptability of HA as a transmitter.
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Affiliation(s)
- Alexia T Scaros
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Aude Andouche
- Laboratoire de Biologie des Organismes et Ecosystemes Aquatiques (BOREA), MNHN, CNRS, SU, UCN, UA, Paris, France
| | - Sébastien Baratte
- Laboratoire de Biologie des Organismes et Ecosystemes Aquatiques (BOREA), MNHN, CNRS, SU, UCN, UA, Paris, France
| | - Roger P Croll
- Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
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10
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Winlow W, Polese G, Moghadam HF, Ahmed IA, Di Cosmo A. Sense and Insensibility - An Appraisal of the Effects of Clinical Anesthetics on Gastropod and Cephalopod Molluscs as a Step to Improved Welfare of Cephalopods. Front Physiol 2018; 9:1147. [PMID: 30197598 PMCID: PMC6117391 DOI: 10.3389/fphys.2018.01147] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 07/31/2018] [Indexed: 12/24/2022] Open
Abstract
Recent progress in animal welfare legislation stresses the need to treat cephalopod molluscs, such as Octopus vulgaris, humanely, to have regard for their wellbeing and to reduce their pain and suffering resulting from experimental procedures. Thus, appropriate measures for their sedation and analgesia are being introduced. Clinical anesthetics are renowned for their ability to produce unconsciousness in vertebrate species, but their exact mechanisms of action still elude investigators. In vertebrates it can prove difficult to specify the differences of response of particular neuron types given the multiplicity of neurons in the CNS. However, gastropod molluscs such as Aplysia, Lymnaea, or Helix, with their large uniquely identifiable nerve cells, make studies on the cellular, subcellular, network and behavioral actions of anesthetics much more feasible, particularly as identified cells may also be studied in culture, isolated from the rest of the nervous system. To date, the sorts of study outlined above have never been performed on cephalopods in the same way as on gastropods. However, criteria previously applied to gastropods and vertebrates have proved successful in developing a method for humanely anesthetizing Octopus with clinical doses of isoflurane, i.e., changes in respiratory rate, color pattern and withdrawal responses. However, in the long term, further refinements will be needed, including recordings from the CNS of intact animals in the presence of a variety of different anesthetic agents and their adjuvants. Clues as to their likely responsiveness to other appropriate anesthetic agents and muscle relaxants can be gained from background studies on gastropods such as Lymnaea, given their evolutionary history.
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Affiliation(s)
- William Winlow
- Department of Biology, University of Naples Federico II, Naples, Italy
- Institute of Ageing and Chronic Diseases, University of Liverpool, Liverpool, United Kingdom
- NPC Newton, Preston, United Kingdom
| | - Gianluca Polese
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Hadi-Fathi Moghadam
- Department of Physiology, Faculty of Medicine, Physiology Research Centre, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | | | - Anna Di Cosmo
- Department of Biology, University of Naples Federico II, Naples, Italy
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11
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Gonzalez-Bellido PT, Scaros AT, Hanlon RT, Wardill TJ. Neural Control of Dynamic 3-Dimensional Skin Papillae for Cuttlefish Camouflage. iScience 2018; 1:24-34. [PMID: 30058000 PMCID: PMC6059360 DOI: 10.1016/j.isci.2018.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 01/10/2018] [Accepted: 01/22/2018] [Indexed: 10/27/2022] Open
Abstract
The color and pattern changing abilities of octopus, squid, and cuttlefish via chromatophore neuromuscular organs are unparalleled. Cuttlefish and octopuses also have a unique muscular hydrostat system in their skin. When this system is expressed, dermal bumps called papillae disrupt body shape and imitate the fine texture of surrounding objects, yet the control system is unknown. Here we report for papillae: (1) the motoneurons and the neurotransmitters that control activation and relaxation, (2) a physiologically fast expression and retraction system, and (3) a complex of smooth and striated muscles that enables long-term expression of papillae through sustained tension in the absence of neural input. The neural circuits controlling acute shape-shifting skin papillae in cuttlefish show homology to the iridescence circuits in squids. The sustained tension in papillary muscles for long-term camouflage utilizes muscle heterogeneity and points toward the existence of a "catch-like" mechanism that would reduce the necessary energy expenditure.
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Affiliation(s)
- Paloma T. Gonzalez-Bellido
- Marine Biological Laboratory, MBL Street, Woods Hole, MA 02543-1015, USA
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Place, Cambridge CB2 3EG, UK
| | - Alexia T. Scaros
- Marine Biological Laboratory, MBL Street, Woods Hole, MA 02543-1015, USA
- Department of Physiology and Biophysics, Dalhousie University, College Street, Halifax, NS B3H 4R2, Canada
| | - Roger T. Hanlon
- Marine Biological Laboratory, MBL Street, Woods Hole, MA 02543-1015, USA
| | - Trevor J. Wardill
- Marine Biological Laboratory, MBL Street, Woods Hole, MA 02543-1015, USA
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Place, Cambridge CB2 3EG, UK
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Bidel F, Di Poi C, Budzinski H, Pardon P, Callewaert W, Arini A, Basu N, Dickel L, Bellanger C, Jozet-Alves C. The antidepressant venlafaxine may act as a neurodevelopmental toxicant in cuttlefish ( Sepia officinalis ). Neurotoxicology 2016; 55:142-153. [DOI: 10.1016/j.neuro.2016.05.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022]
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13
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Polese G, Bertapelle C, Di Cosmo A. Olfactory organ of Octopus vulgaris: morphology, plasticity, turnover and sensory characterization. Biol Open 2016; 5:611-9. [PMID: 27069253 PMCID: PMC4874359 DOI: 10.1242/bio.017764] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/24/2016] [Indexed: 01/25/2023] Open
Abstract
The cephalopod olfactory organ was described for the first time in 1844 by von Kölliker, who was attracted to the pair of small pits of ciliated cells on each side of the head, below the eyes close to the mantle edge, in both octopuses and squids. Several functional studies have been conducted on decapods but very little is known about octopods. The morphology of the octopus olfactory system has been studied, but only to a limited extent on post-hatching specimens, and the only paper on adult octopus gives a minimal description of the olfactory organ. Here, we describe the detailed morphology of young male and female Octopus vulgaris olfactory epithelium, and using a combination of classical morphology and 3D reconstruction techniques, we propose a new classification for O. vulgaris olfactory sensory neurons. Furthermore, using specific markers such as olfactory marker protein (OMP) and proliferating cell nuclear antigen (PCNA) we have been able to identify and differentially localize both mature olfactory sensory neurons and olfactory sensory neurons involved in epithelium turnover. Taken together, our data suggest that the O. vulgaris olfactory organ is extremely plastic, capable of changing its shape and also proliferating its cells in older specimens.
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Affiliation(s)
- Gianluca Polese
- Department of Biology, University of Napoli Federico II, Napoli, NA 80126, Italy
| | - Carla Bertapelle
- Department of Biology, University of Napoli Federico II, Napoli, NA 80126, Italy
| | - Anna Di Cosmo
- Department of Biology, University of Napoli Federico II, Napoli, NA 80126, Italy
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Polese G, Bertapelle C, Di Cosmo A. Role of olfaction in Octopus vulgaris reproduction. Gen Comp Endocrinol 2015; 210:55-62. [PMID: 25449183 DOI: 10.1016/j.ygcen.2014.10.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/10/2014] [Accepted: 10/13/2014] [Indexed: 11/25/2022]
Abstract
The olfactory system in any animal is the primary sensory system that responds to chemical stimuli emanating from a distant source. In aquatic animals "Odours" are molecules in solution that guide them to locate food, partners, nesting sites, and dangers to avoid. Fish, crustaceans and aquatic molluscs possess sensory systems that have anatomical similarities to the olfactory systems of land-based animals. Molluscs are a large group of aquatic and terrestrial animals that rely heavily on chemical communication with a generally dispersed sense of touch and chemical sensitivity. Cephalopods, the smallest class among extant marine molluscs, are predators with high visual capability and well developed vestibular, auditory, and tactile systems. Nevertheless they possess a well developed olfactory organ, but to date almost nothing is known about the mechanisms, functions and modulation of this chemosensory structure in octopods. Cephalopod brains are the largest of all invertebrate brains and across molluscs show the highest degree of centralization. The reproductive behaviour of Octopus vulgaris is under the control of a complex set of signal molecules such as neuropeptides, neurotransmitters and sex steroids that guide the behaviour from the level of individuals in evaluating mates, to stimulating or deterring copulation, to sperm-egg chemical signalling that promotes fertilization. These signals are intercepted by the olfactory organs and integrated in the olfactory lobes in the central nervous system. In this context we propose a model in which the olfactory organ and the olfactory lobe of O. vulgaris could represent the on-off switch between food intake and reproduction.
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Affiliation(s)
- Gianluca Polese
- University of Napoli "Federico II", Department of Biology, via Cinthia, Campus MSA, ed. 7, 80126 Napoli, Italy.
| | - Carla Bertapelle
- University of Napoli "Federico II", Department of Biology, via Cinthia, Campus MSA, ed. 7, 80126 Napoli, Italy.
| | - Anna Di Cosmo
- University of Napoli "Federico II", Department of Biology, via Cinthia, Campus MSA, ed. 7, 80126 Napoli, Italy.
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Spady BL, Watson SA, Chase TJ, Munday PL. Projected near-future CO2 levels increase activity and alter defensive behaviours in the tropical squid Idiosepius pygmaeus. Biol Open 2014; 3:1063-70. [PMID: 25326517 PMCID: PMC4232764 DOI: 10.1242/bio.20149894] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Carbon dioxide (CO2) levels projected to occur in the oceans by the end of this century cause a range of behavioural effects in fish, but whether other highly active marine organisms, such as cephalopods, are similarly affected is unknown. We tested the effects of projected future CO2 levels (626 and 956 µatm) on the behaviour of male two-toned pygmy squid, Idiosepius pygmaeus. Exposure to elevated CO2 increased the number of active individuals by 19-25% and increased movement (number of line-crosses) by nearly 3 times compared to squid at present-day CO2. Squid vigilance and defensive behaviours were also altered by elevated CO2 with >80% of individuals choosing jet escape responses over defensive arm postures in response to a visual startle stimulus, compared with 50% choosing jet escape responses at control CO2. In addition, more escape responses were chosen over threat behaviours in body pattern displays at elevated CO2 and individuals were more than twice as likely to use ink as a defence strategy at 956 µatm CO2, compared with controls. Increased activity could lead to adverse effects on energy budgets as well as increasing visibility to predators. A tendency to respond to a stimulus with escape behaviours could increase survival, but may also be energetically costly and could potentially lead to more chases by predators compared with individuals that use defensive postures. These results demonstrate that projected future ocean acidification affects the behaviours of a tropical squid species.
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Affiliation(s)
- Blake L Spady
- College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Sue-Ann Watson
- College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Tory J Chase
- College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia
| | - Philip L Munday
- College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
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16
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Derby CD. Cephalopod ink: production, chemistry, functions and applications. Mar Drugs 2014; 12:2700-30. [PMID: 24824020 PMCID: PMC4052311 DOI: 10.3390/md12052700] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/10/2014] [Accepted: 04/14/2014] [Indexed: 01/17/2023] Open
Abstract
One of the most distinctive and defining features of coleoid cephalopods—squid, cuttlefish and octopus—is their inking behavior. Their ink, which is blackened by melanin, but also contains other constituents, has been used by humans in various ways for millennia. This review summarizes our current knowledge of cephalopod ink. Topics include: (1) the production of ink, including the functional organization of the ink sac and funnel organ that produce it; (2) the chemical components of ink, with a focus on the best known of these—melanin and the biochemical pathways involved in its production; (3) the neuroecology of the use of ink in predator-prey interactions by cephalopods in their natural environment; and (4) the use of cephalopod ink by humans, including in the development of drugs for biomedical applications and other chemicals for industrial and other commercial applications. As is hopefully evident from this review, much is known about cephalopod ink and inking, yet more striking is how little we know. Towards closing that gap, future directions in research on cephalopod inking are suggested.
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Affiliation(s)
- Charles D Derby
- Neuroscience Institute and Department of Biology, Georgia State University, P.O. Box 5030, Atlanta, GA 30302-5030, USA.
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Fiorito G, Affuso A, Anderson DB, Basil J, Bonnaud L, Botta G, Cole A, D'Angelo L, De Girolamo P, Dennison N, Dickel L, Di Cosmo A, Di Cristo C, Gestal C, Fonseca R, Grasso F, Kristiansen T, Kuba M, Maffucci F, Manciocco A, Mark FC, Melillo D, Osorio D, Palumbo A, Perkins K, Ponte G, Raspa M, Shashar N, Smith J, Smith D, Sykes A, Villanueva R, Tublitz N, Zullo L, Andrews P. Cephalopods in neuroscience: regulations, research and the 3Rs. INVERTEBRATE NEUROSCIENCE 2014; 14:13-36. [PMID: 24385049 PMCID: PMC3938841 DOI: 10.1007/s10158-013-0165-x] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Accepted: 11/08/2013] [Indexed: 12/18/2022]
Abstract
Cephalopods have been utilised in neuroscience research for more than 100 years particularly because of their phenotypic plasticity, complex and centralised nervous system, tractability for studies of learning and cellular mechanisms of memory (e.g. long-term potentiation) and anatomical features facilitating physiological studies (e.g. squid giant axon and synapse). On 1 January 2013, research using any of the about 700 extant species of "live cephalopods" became regulated within the European Union by Directive 2010/63/EU on the "Protection of Animals used for Scientific Purposes", giving cephalopods the same EU legal protection as previously afforded only to vertebrates. The Directive has a number of implications, particularly for neuroscience research. These include: (1) projects will need justification, authorisation from local competent authorities, and be subject to review including a harm-benefit assessment and adherence to the 3Rs principles (Replacement, Refinement and Reduction). (2) To support project evaluation and compliance with the new EU law, guidelines specific to cephalopods will need to be developed, covering capture, transport, handling, housing, care, maintenance, health monitoring, humane anaesthesia, analgesia and euthanasia. (3) Objective criteria need to be developed to identify signs of pain, suffering, distress and lasting harm particularly in the context of their induction by an experimental procedure. Despite diversity of views existing on some of these topics, this paper reviews the above topics and describes the approaches being taken by the cephalopod research community (represented by the authorship) to produce "guidelines" and the potential contribution of neuroscience research to cephalopod welfare.
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Brown ER, Piscopo S. Synaptic plasticity in cephalopods; more than just learning and memory? INVERTEBRATE NEUROSCIENCE 2013; 13:35-44. [PMID: 23549756 DOI: 10.1007/s10158-013-0150-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 02/23/2013] [Indexed: 12/23/2022]
Abstract
The outstanding behavioural capacity of cephalopods is underpinned by a highly sophisticated nervous system anatomy and neural mechanisms that often differ significantly from similarly complex systems in vertebrates and insects. Cephalopods exhibit considerable behavioural flexibility and adaptability, and it might be expected that this should be supported by evident cellular and synaptic plasticity. Here, we review what little is known of the cellular mechanisms that underlie plasticity in cephalopods, particularly from the point of view of synaptic function. We conclude that cephalopods utilise short-, medium-, and long-term plasticity mechanisms that are superficially similar to those so far described in vertebrate and insect synapses. These mechanisms, however, often differ significantly from those in other animals at the biophysical level and are deployed not just in the central nervous system, but also to a limited extent in the peripheral nervous system and neuromuscular junctions.
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Affiliation(s)
- Euan R Brown
- Institute of Biological Chemistry, Biophysics and Bioengineering, School of Engineering and Physical Sciences, Heriot Watt University, William Perkin Building, Edinburgh EH14 4AS, UK.
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Conti L, Limon A, Palma E, Miledi R. Microtransplantation of cellular membranes from squid stellate ganglion reveals ionotropic GABA receptors. THE BIOLOGICAL BULLETIN 2013; 224:47-52. [PMID: 23493508 DOI: 10.1086/bblv224n1p47] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The squid has been the most studied cephalopod, and it has served as a very useful model for investigating the events associated with nerve impulse generation and synaptic transmission. While the physiology of squid giant axons has been extensively studied, very little is known about the distribution and function of the neurotransmitters and receptors that mediate inhibitory transmission at the synapses. In this study we investigated whether γ-aminobutyric acid (GABA) activates neurotransmitter receptors in stellate ganglia membranes. To overcome the low abundance of GABA-like mRNAs in invertebrates and the low expression of GABA in cephalopods, we used a two-electrode voltage clamp technique to determine if Xenopus laevis oocytes injected with cell membranes from squid stellate ganglia responded to GABA. Using this method, membrane patches containing proteins and ion channels from the squid's stellate ganglion were incorporated into the surface of oocytes. We demonstrated that GABA activates membrane receptors in cellular membranes isolated from squid stellate ganglia. Using the same approach, we were able to record native glutamate-evoked currents. The squid's GABA receptors showed an EC(50) of 98 μmol l(-1) to GABA and were inhibited by zinc (IC(50) = 356 μmol l(-1)). Interestingly, GABA receptors from the squid were only partially blocked by bicuculline. These results indicate that the microtransplantation of native cell membranes is useful to identify and characterize scarce membrane proteins. Moreover, our data also support the role of GABA as an ionotropic neurotransmitter in cephalopods, acting through chloride-permeable membrane receptors.
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Affiliation(s)
- Luca Conti
- Grass Laboratory at the Marine Biological Laboratory, 7 MBL St., Woods Hole, MA 02543, USA.
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De Lisa E, Paolucci M, Di Cosmo A. Conservative nature of oestradiol signalling pathways in the brain lobes of octopus vulgaris involved in reproduction, learning and motor coordination. J Neuroendocrinol 2012; 24:275-84. [PMID: 21988192 DOI: 10.1111/j.1365-2826.2011.02240.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Oestradiol plays crucial roles in the mammalian brain by modulating reproductive behaviour, neural plasticity and pain perception. The cephalopod Octopus vulgaris is considered, along with its relatives, to be the most behaviourally advanced invertebrate, although the neurophysiological basis of its behaviours, including pain perception, remain largely unknown. In the present study, using a combination of molecular and imaging techniques, we found that oestradiol up-regulated O. vulgaris gonadotrophin-releasing hormone (Oct-GnRH) and O. vulgaris oestrogen receptor (Oct-ER) mRNA levels in the olfactory lobes; in turn, Oct-ER mRNA was regulated by NMDA in lobes involved in learning and motor coordination. Fluorescence resonance energy transfer analysis revealed that oestradiol binds Oct-ER causing conformational modifications and nuclear translocation consistent with the classical genomic mechanism of the oestrogen receptor. Moreover, oestradiol triggered a calcium influx and cyclic AMP response element binding protein phosphorylation via membrane receptors, providing evidence for a rapid nongenomic action of oestradiol in O. vulgaris. In the present study, we demonstrate, for the first time, the physiological role of oestradiol in the brain lobes of O. vulgaris involved in reproduction, learning and motor coordination.
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Affiliation(s)
- E De Lisa
- Department of Structural and Functional Biology, University of Napoli Federico II, Napoli, Italy.
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Bardou I, Leprince J, Chichery R, Vaudry H, Agin V. Vasopressin/oxytocin-related peptides influence long-term memory of a passive avoidance task in the cuttlefish, Sepia officinalis. Neurobiol Learn Mem 2010; 93:240-7. [DOI: 10.1016/j.nlm.2009.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 10/14/2009] [Accepted: 10/20/2009] [Indexed: 11/17/2022]
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Di Cristo C, De Lisa E, Di Cosmo A. Control of GnRH expression in the olfactory lobe of Octopus vulgaris. Peptides 2009; 30:538-44. [PMID: 18703100 DOI: 10.1016/j.peptides.2008.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2008] [Revised: 06/29/2008] [Accepted: 07/10/2008] [Indexed: 11/30/2022]
Abstract
In the cephalopod mollusk Octopus vulgaris, the gonadotropic hormone released by the optic gland controls sexual maturity. Several lobes of the central nervous system control the activity of this gland. In one of these lobes, the olfactory lobe, a gonadotropin releasing hormone (GnRH) neuronal system has been described. We assume that several inputs converge on the olfactory lobes in order to activate GnRH neurons and that a glutamatergic system mediates the integration of stimuli on these neuropeptidergic neurons. The presence of N-methyl-d-aspartate (NMDA) receptor immunoreactivity in the neuropil of olfactory lobes and in the fibers of the optic gland nerve, along with the GnRH nerve endings strongly supports this hypothesis. A distinctive role in the control of GnRH secretion has also been attributed, in vertebrates, to nitric oxide (NO). The lobes and nerves involved in the nervous control of reproduction in Octopus contain nitric oxide synthase (NOS). Using a set of experiments aimed at manipulate a putative l-glutamate/NMDA/NO signal transduction pathway, we have demonstrated, by quantitative real-time PCR, that NMDA enhances the expression of GnRH mRNA in a dose-response manner. The reverting effect of a selective antagonist of NMDA receptors (NMDARs), 2-amino-5-phosphopentanoic acid (D-APV), confirms that such an enhancing action is a NMDA receptor-mediated response. Nitric oxide and calcium also play a positive role on GnRH mRNA expression. The results suggest that in Octopusl-glutamate could be a key molecule in the nervous control of sexual maturation.
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Affiliation(s)
- Carlo Di Cristo
- Department of Biological and Environmental Sciences, University of Sannio, Benevento, Italy
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Moccia F, Di Cristo C, Winlow W, Di Cosmo A. GABA(A)- and AMPA-like receptors modulate the activity of an identified neuron within the central pattern generator of the pond snail Lymnaea stagnalis. INVERTEBRATE NEUROSCIENCE 2009; 9:29-41. [PMID: 19214610 DOI: 10.1007/s10158-009-0086-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 01/06/2009] [Indexed: 11/28/2022]
Abstract
To examine the neurochemistry underlying the firing of the RPeD1 neuron in the respiratory central pattern generator of the pond snail, Lymnaea stagnalis, we examined electrophysiologically and pharmacologically either "active" or "silent" preparations by intracellular recording and pharmacology. GABA inhibited electrical firing by hyperpolarizing RPeD1, while picrotoxin, an antagonist of GABA(A) receptors, excited silent cells and reversed GABA-induced inhibition. Action potential activity was terminated by 1 mM glutamate (Glu) while silent cells were depolarized by the GluR agonists, AMPA, and NMDA. Kainate exerted a complex triphasic effect on membrane potential. However, only bath application of AMPA desensitized the firing. These data indicate that GABA inhibits RPeD1 via activation of GABA(A) receptors, while Glu stimulates the neuron by activating AMPA-sensitive GluRs.
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Affiliation(s)
- Francesco Moccia
- Department of Structural and Functional Biology, University of Naples "Federico II" Complesso Universitario, Monte S. Angelo, viale Cinthia, 80126 Naples, Italy
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