Structure-Function of Serotonin in Bivalve Molluscs

Alavi, Sayyed Mohammad Hadi; Nagasawa, Kazue; Takahashi, Keisuke; Osada, Makoto

doi:10.5772/intechopen.69165

Cited by 11 publications

(12 citation statements)

References 118 publications

(152 reference statements)

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“…Actually, we found that approximately 56% of the cells in the CPGs of Cr. grayanus are 5-HT-LIP neurons (the "serotonic center" of the visceral nervous system consisting of the CPG, VG and their nerve connections), in agreement with previous observations that in the clams Tresus capax and Macoma nasuta (Smith, 1982;Alavi et al, 2017) the level of 5-HT is higher in the CPG than the VG. The 5-HT content of bivalve ganglia is influenced by the reproductive cycle, seasonal physiological activities, and various stress factors (Fingerman and Nagabhushanam, 1997).…”

Section: Discussionsupporting

confidence: 91%

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Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus

et al. 2020

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In bivalves neurotransmitters are involved in a variety of behaviors, but their diversity and distribution in the nervous system of these organisms remains somewhat unclear. Here, we first examined immunohistochemically the distributions of neurons containing different neurotransmitters, neuropeptides, and related enzymes, as well as the proliferative status of neurons in the ganglia of the mussel Crenomytilus grayanus. H-Phe-Met-Arg-Phe-NH2 (FMRFamide), choline acetyltransferase (ChAT), γaminobutyric acid (GABA) and tyrosine hydroxylase (TH) were found to be expressed by neurons in all the ganglia, whereas serotonin (5-HT) neurons were found only in the cerebropleural and pedal, but not visceral ganglia. Moreover, incubation of living mussels in the presence of a 5-HT precursor (5-HTP) confirmed the absence of 5-HT-containing neurons from the visceral ganglia, indicating that the "serotonin center" of the visceral nervous system is located in the cerebral ganglia. Furthermore, immunostaining of molecules related to neurotransmission together with α-acetylated tubulin demonstrated that this cytoskeletal protein may be a potential pan-neuronal marker in bivalves. Adult mussel neurons do not proliferate, but a population of proliferating PCNA-LIP cells which do not express any of the neurotransmitters examined, perhaps glia cells, was detected in the ganglia. These novel findings suggest that the nervous system of bivalves contains a broad variety of signal molecules most likely involved in the regulation of different physiological and behavioral processes. In addition, proliferating cells may maintain and renew glial cells and neurons throughout the lives of bivalves.

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Section: Discussionsupporting

confidence: 91%

“…grayanus, in 49.8% of the total number of neurons in the visceral ganglia up to 87% in the cerebropleural ganglia. Moreover, the nervous system of bivalves contains much higher 5-HT concentrations than that of other invertebrates (Alavi et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus

et al. 2020

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“…This module was enriched for tryptophan metabolic processes and included the tryptophan 2,3-dioxygenase coding gene (TDO), a pivotal regulator of systemic tryptophan levels also involved in the response to oxidative stress ( 67 , 68 ). Tryptophan is the precursor of 5-hydroxytryptamine (5-HT), a bivalve serotonin transmitter that plays critical roles in numerous physiological functions (e.g., reproduction ( 69 )). In the coral Montastrea faveolata (now known as Orbicella faveolata ), TDO (called AGAP in the reference [94]) was up-regulated in response to ultraviolet radiation in larvae and was associated with individual fitness (locomotion and settlement) impairment in later stages ( 70 ).…”

Section: Discussionmentioning

confidence: 99%

Identifying conserved molecular mechanisms of thermo-acclimation in symbiotic organisms

Brahmi

et al. 2018

Preprint

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25 26 Seawater temperature rise in French Polynesia has repeatedly resulted in symbiosis breakdown 27 between giant clam (Tridacna maxima) and dinoflagellates (Symbiodinium spp.), particularly in 28 small individuals. Herein, we explored the physiological and gene expression responses of the 29 clam hosts and their photosynthetically active symbionts over a 65-day experiment in which 30 clams were exposed to either normal or environmentally relevant elevated seawater temperatures. 31These data were combined with publicly available data for both free-living Symbiodinium (clades 32 C1 and F) and Symbiodinium spp. in hospite with the coral Pocillopora damicornis. Gene module 33 preservation analysis revealed that the function of the symbionts' photosystem II was impaired at 34 high temperatures, and this response was conserved across all holobionts and Symbiodinium 35 clades examined. Similarly, activation of the phytohormone abscisic acid signaling and 36 epigenetics modulation appeared to be a key response mechanisms for symbionts in hospite with 37 giant clams exposed to high temperatures and also distinguish thermo-tolerant from thermo-38 sensitive Symbiodinium C1 phenotypes. 39 40MAIN TEXT 41 42Introduction 43 44Giant clams are mixotrophic organisms living in obligatory symbiosis with photosynthetic 45 dinoflagellates of the genus Symbiodinium (1, 2). Symbiodinium spp. associate not only with giant 46 clams, but with a diverse array of marine invertebrates, namely sponges, molluscs and cnidarians; 47 indeed, the coral-Symbiodinium symbiosis is the functional basis of all coral reefs (3). While in 48 scleractinian corals symbionts are located intracellularly, in giant clams they reside extracellularly 49 inside a tubular system called "Z-tubules," which are 1) found in the outer epithelium of the 50 mantle and 2) connected to the stomach (4). These in hospite dinoflagellates are known to provide 51 nutrients to the clam hosts via photosynthesis and may account for a major part of the clams' 52 energy needs (depending on the species and the life history stage) (5-9). The Symbiodinium genus 53 includes nine different clades with well characterized molecular and physiological differences 54 (10-12). One Symbiodinium clade, clade A (S. microadriaticum and S. fitti), has been recurrently 55 found in symbiosis with Tridacna maxima though members of clades C and D have been found in 56 clam tissues, as well (10,(13)(14)(15)(16)(17). Depending of the species, cladal representation of symbiont 57 types have been found to vary with individual size (mostly observed in T. squamosa), as well as 58 across environmental gradients (especially seawater temperatures) (15, 16). In French Polynesia, 59 eastern Tuamotu's archipelagos were historically characterized by high densities of small giant 60 clams (18)(19)(20). Recent mortality episodes and/or "bleaching" events in the Tuamotu Islands have, 61 however, been reported, including 1) a massive mortality event in 2009 that reduced the small 62 giant clam population by 90% at...

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“…Tryptophan is the precursor of 5-hydroxytryptamine (5-HT), a bivalve serotonin transmitter that plays critical roles in numerous physiological functions (e.g., reproduction; Alavi, Nagasawa, Takahashi, & Osada, 2017). In larvae from the coral Orbicella faveolata, TDO (referred to as AGAP) was upregulated in response to ultraviolet radiation, and larval fitness (locomotion and settlement) went on to suffer (Aranda et al, 2011).…”

Section: Effect Of Prolonged Exposure To Elevated Temperature On Thmentioning

confidence: 99%

Molecular mechanisms of acclimation to long‐term elevated temperature exposure in marine symbioses

Monteiro

Brahmi

Mayfield

et al. 2019

Global Change Biology

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Seawater temperature rise in French Polynesia has repeatedly resulted in the bleaching of corals and giant clams. Because giant clams possess distinctive ectosymbiotic features, they represent a unique and powerful model for comparing molecular pathways involved in (a) maintenance of symbiosis and (b) acquisition of thermotolerance among coral reef organisms. Herein, we explored the physiological and transcriptomic responses of the clam hosts and their photosynthetically active symbionts over a 65 day experiment in which clams were exposed to either normal or environmentally relevant elevated seawater temperatures. Additionally, we used metabarcoding data coupled with in situ sampling/survey data to explore the relative importance of holobiont adaptation (i.e., a symbiont community shift) versus acclimation (i.e., physiological changes at the molecular level) in the clams’ responses to environmental change. We finally compared transcriptomic data to publicly available genomic datasets for Symbiodiniaceae dinoflagellates (both cultured and in hospite with the coral Pocillopora damicornis) to better tease apart the responses of both hosts and specific symbiont genotypes in this mutualistic association. Gene module preservation analysis revealed that the function of the symbionts’ photosystem II was impaired at high temperature, and this response was also found across all holobionts and Symbiodiniaceae lineages examined. Similarly, epigenetic modulation appeared to be a key response mechanism for symbionts in hospite with giant clams exposed to high temperatures, and such modulation was able to distinguish thermotolerant from thermosensitive Cladocopium goreaui ecotypes; epigenetic processes may, then, represent a promising research avenue for those interested in coral reef conservation in this era of changing global climate.

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Structure-Function of Serotonin in Bivalve Molluscs

Cited by 11 publications

References 118 publications

Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus

Distribution of Molecules Related to Neurotransmission in the Nervous System of the Mussel Crenomytilus grayanus

Identifying conserved molecular mechanisms of thermo-acclimation in symbiotic organisms

Molecular mechanisms of acclimation to long‐term elevated temperature exposure in marine symbioses

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