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Kotsyuba E, Dyachuk V. Role of the Neuroendocrine System of Marine Bivalves in Their Response to Hypoxia. Int J Mol Sci 2023; 24:ijms24021202. [PMID: 36674710 PMCID: PMC9865615 DOI: 10.3390/ijms24021202] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/28/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Mollusks comprise one of the largest phylum of marine invertebrates. With their great diversity of species, various degrees of mobility, and specific behavioral strategies, they haveoccupied marine, freshwater, and terrestrial habitats and play key roles in many ecosystems. This success is explained by their exceptional ability to tolerate a wide range of environmental stresses, such as hypoxia. Most marine bivalvemollusksare exposed to frequent short-term variations in oxygen levels in their marine or estuarine habitats. This stressfactor has caused them to develop a wide variety of adaptive strategies during their evolution, enabling to mobilize rapidly a set of behavioral, physiological, biochemical, and molecular defenses that re-establishing oxygen homeostasis. The neuroendocrine system and its related signaling systems play crucial roles in the regulation of various physiological and behavioral processes in mollusks and, hence, can affect hypoxiatolerance. Little effort has been made to identify the neurotransmitters and genes involved in oxygen homeostasis regulation, and the molecular basis of the differences in the regulatory mechanisms of hypoxia resistance in hypoxia-tolerant and hypoxia-sensitive bivalve species. Here, we summarize current knowledge about the involvement of the neuroendocrine system in the hypoxia stress response, and the possible contributions of various signaling molecules to this process. We thusprovide a basis for understanding the molecular mechanisms underlying hypoxic stress in bivalves, also making comparisons with data from related studies on other species.
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Effect of Air Exposure-Induced Hypoxia on Neurotransmitters and Neurotransmission Enzymes in Ganglia of the Scallop Azumapecten farreri. Int J Mol Sci 2022; 23:ijms23042027. [PMID: 35216143 PMCID: PMC8878441 DOI: 10.3390/ijms23042027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/09/2022] [Accepted: 02/09/2022] [Indexed: 02/04/2023] Open
Abstract
The nervous system expresses neuromolecules that play a crucial role in regulating physiological processes. Neuromolecule synthesis can be regulated by oxygen-dependent enzymes. Bivalves are a convenient model for studying air exposure-induced hypoxia. Here, we studied the effects of hypoxia on the expression and dynamics of neurotransmitters, and on neurotransmitter enzyme distribution, in the central nervous system (CNS) of the scallop Azumapecten farreri. We analyzed the expression of the neurotransmitters FMRFamide and serotonin (5-HT) and the choline acetyltransferase (CHAT) and universal NO-synthase (uNOS) enzymes during air exposure-induced hypoxia. We found that, in early-stage hypoxia, total serotonin content decreased in some CNS regions but increased in others. CHAT-lir cell numbers increased in all ganglia after hypoxia; CHAT probably appears de novo in accessory ganglia. Short-term hypoxia caused increased uNOS-lir cell numbers, while long-term exposure led to a reduction in their number. Thus, hypoxia weakly influences the number of FMRFamide-lir neurons in the visceral ganglion and does not affect peptide expression in the pedal ganglion. Ultimately, we found that the localization and level of synthesis of neuromolecules, and the numbers of cells expressing these molecules, vary in the scallop CNS during hypoxia exposure. This indicates their possible involvement in hypoxia resistance mechanisms.
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Vogeler S, Carboni S, Li X, Nevejan N, Monaghan SJ, Ireland JH, Joyce A. Bivalves are NO different: nitric oxide as negative regulator of metamorphosis in the Pacific oyster, Crassostrea gigas. BMC DEVELOPMENTAL BIOLOGY 2020; 20:23. [PMID: 33228520 PMCID: PMC7686737 DOI: 10.1186/s12861-020-00232-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/11/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND Nitric oxide (NO) is presumed to be a regulator of metamorphosis in many invertebrate species, and although NO pathways have been comparatively well-investigated in gastropods, annelids and crustaceans, there has been very limited research on the effects of NO on metamorphosis in bivalve shellfish. RESULTS In this paper, we investigate the effects of NO pathway inhibitors and NO donors on metamorphosis induction in larvae of the Pacific oyster, Crassostrea gigas. The nitric oxides synthase (NOS) inhibitors s-methylisothiourea hemisulfate salt (SMIS), aminoguanidine hemisulfate salt (AGH) and 7-nitroindazole (7-NI) induced metamorphosis at 75, 76 and 83% respectively, and operating in a concentration-dependent manner. Additional induction of up to 54% resulted from exposures to 1H-[1,2,4]Oxadiazole[4,3-a]quinoxalin-1-one (ODQ), an inhibitor of soluble guanylyl cyclase, with which NO interacts to catalyse the synthesis of cyclic guanosine monophosphate (cGMP). Conversely, high concentrations of the NO donor sodium nitroprusside dihydrate in combination with metamorphosis inducers epinephrine, MK-801 or SMIS, significantly decreased metamorphosis, although a potential harmful effect of excessive NO unrelated to metamorphosis pathway cannot be excluded. Expression of CgNOS also decreased in larvae after metamorphosis regardless of the inducers used, but intensified again post-metamorphosis in spat. Fluorescent detection of NO in competent larvae with DAF-FM diacetate and localisation of the oyster nitric oxide synthase CgNOS expression by in-situ hybridisation showed that NO occurs primarily in two key larval structures, the velum and foot. cGMP was also detected in the foot using immunofluorescent assays, and is potentially involved in the foot's smooth muscle relaxation. CONCLUSION Together, these results suggest that the NO pathway acts as a negative regulator of metamorphosis in Pacific oyster larvae, and that NO reduction induces metamorphosis by inhibiting swimming or crawling behaviour, in conjunction with a cascade of additional neuroendocrine downstream responses.
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Affiliation(s)
- Susanne Vogeler
- Department of Marine Science, University of Gothenburg, Carl Skottbergsgata 22 B, 41319, Gothenburg, Sweden
| | - Stefano Carboni
- Institute of Aquaculture, University of Stirling, FK9 4LA, Stirling, Scotland, UK
| | - Xiaoxu Li
- South Australia Research and Development Institute Aquatic Sciences Centre, 2 Hamra Ave, West Beach, SA, 5024, Australia
| | - Nancy Nevejan
- Department of Animal Production, Ghent University, Coupure Links 653, 9000, Ghent, Belgium
| | - Sean J Monaghan
- Institute of Aquaculture, University of Stirling, FK9 4LA, Stirling, Scotland, UK
| | - Jacqueline H Ireland
- Institute of Aquaculture, University of Stirling, FK9 4LA, Stirling, Scotland, UK
| | - Alyssa Joyce
- Department of Marine Science, University of Gothenburg, Carl Skottbergsgata 22 B, 41319, Gothenburg, Sweden.
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Ray A, Gautam A, Das S, Pal K, Das S, Karmakar P, Ray M, Ray S. Effects of copper oxide nanoparticle on gill filtration rate, respiration rate, hemocyte associated immune parameters and oxidative status of an Indian freshwater mussel. Comp Biochem Physiol C Toxicol Pharmacol 2020; 237:108855. [PMID: 32781292 DOI: 10.1016/j.cbpc.2020.108855] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/29/2020] [Accepted: 07/18/2020] [Indexed: 12/13/2022]
Abstract
Waterbodies of India support a wide range of molluscs including Lamellidens marginalis, a pearl forming edible mussel of ecological significance. Report of copper oxide nanoparticle toxicity in Indian molluscs is limited in scientific literature. L. marginalis is a gill respiring filter feeder, which is toxicologically vulnerable to exposure of copper oxide nanoparticles liberated from electrical, textile and polymer industries. Experimental exposure of copper oxide nanoparticles for 7 days yielded a decrease in gill filtration rate, respiration rate, total count and phagocytic response of hemocytes, the chief immunoeffector cells of L. marginalis. Nanoparticle exposure resulted in decrease of phagocytic response of mussel hemocytes. Decrease in nitric oxide generation and phenoloxidase activity were recorded in L. marginalis exposed to 0.5, 1 and 5 mg copper oxide nanoparticles per litre of water for 7 and 14 days. Superoxide anion generation in hemocytes was increased under the exposure of copper oxide nanoparticles. Increase in superoxide anion and decrease in the activities of superoxide dismutase and catalase were indicative to oxidative stress in mussels. Copper oxide nanoparticle induced shift in filtration and respiration rate along with the hemocyte associated immune parameters were suggestive to an acute immunophysiological stress in L. marginalis. We estimated the functional performance of gill and physiological status of aquatic respiration in L. marginalis exposed to copper oxide nanoparticles. A parallel set of estimation of each parameter was carried out in L. marginalis exposed to identical copper sulphate concentrations to record and compare the ionic toxicity of copper in the same specimen.
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Affiliation(s)
- Abhishek Ray
- Aquatic Toxicology Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, West Bengal, India
| | - Arunodaya Gautam
- Aquatic Toxicology Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, West Bengal, India
| | - Santanu Das
- Aquatic Toxicology Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, West Bengal, India
| | - Kunal Pal
- Nanobiotechnology Laboratory, Department of Life Science and Biotechnology, Jadavpur University, 188 Raja Subodh Chandra Mallick Road, Kolkata 700032, West Bengal, India
| | - Subhadeep Das
- Semiochemicals and Lipid Laboratory, Department of Life Science, Presidency University, 86/1, College Street, Kolkata 700073, West Bengal, India
| | - Parimal Karmakar
- Nanobiotechnology Laboratory, Department of Life Science and Biotechnology, Jadavpur University, 188 Raja Subodh Chandra Mallick Road, Kolkata 700032, West Bengal, India
| | - Mitali Ray
- Aquatic Toxicology Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, West Bengal, India
| | - Sajal Ray
- Aquatic Toxicology Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, West Bengal, India.
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Abdel-Latif HMR, Dawood MAO, Menanteau-Ledouble S, El-Matbouli M. Environmental transformation of n-TiO 2 in the aquatic systems and their ecotoxicity in bivalve mollusks: A systematic review. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 200:110776. [PMID: 32474243 DOI: 10.1016/j.ecoenv.2020.110776] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 05/14/2020] [Accepted: 05/15/2020] [Indexed: 06/11/2023]
Abstract
Over the past decades, titanium dioxide nanoparticles (n-TiO2) have been extensively used in several industrial applications and the manufacture of novel consumer products. Although strict regulations have been put in place to limit their release into the aquatic environment, these nanoparticles can still be found at elevated levels within the environment, which can result in toxic effects on exposed organisms and has possible implications in term of public health. Bivalve mollusks are a unique and ideal group of shellfish for the study and monitoring the aquatic pollution by n-TiO2 because of their filter-feeding behaviour and ability to accumulate toxicants in their tissues. In these animals, exposure to n-TiO2 leads to oxidative stress, immunotoxicity, neurotoxicity, and genotoxicity, as well as behavioral and physiological changes. This review summarizes the uptake, accumulation, and fate of n-TiO2 in aquatic environments and the possible interactions between n-TiO2 and other contaminants such as heavy metals and organic pollutants. Moreover, the toxicological impacts and mechanisms of action are discussed for a wide range of bivalve mollusks. This data underlines the pressing need for additional knowledge and future research plans for the development of control strategies to mitigate the release of n-TiO2 to the aquatic environment to prevent the toxicological impacts on bivalves and protect public health.
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Affiliation(s)
- Hany M R Abdel-Latif
- Department of Poultry and Fish Diseases, Faculty of Veterinary Medicine, Alexandria University, Edfina, 22758, Behera province, Egypt.
| | - Mahmoud A O Dawood
- Department of Animal Production, Faculty of Agriculture, Kafrelsheikh University, 33516, Kafrelsheikh, Egypt; School of Freshwater Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, 53204, USA.
| | | | - Mansour El-Matbouli
- Clinical Division of Fish Medicine, University of Veterinary Medicine, Vienna, Austria.
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Shi W, Han Y, Guan X, Rong J, Du X, Zha S, Tang Y, Liu G. Anthropogenic Noise Aggravates the Toxicity of Cadmium on Some Physiological Characteristics of the Blood Clam Tegillarca granosa. Front Physiol 2019; 10:377. [PMID: 31001147 PMCID: PMC6456685 DOI: 10.3389/fphys.2019.00377] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 03/18/2019] [Indexed: 12/30/2022] Open
Abstract
Widespread applications of cadmium (Cd) in various products have caused Cd contamination in marine ecosystems. Meanwhile, human activities in the ocean have also generated an increasing amount of noise in recent decades. Although anthropogenic noise and Cd contaminants could be present simultaneously in marine environments, the physiological responses of marine bivalve mollusks upon coexposure to anthropogenic noise and toxic metal contaminants, including Cd remain unclear. Therefore, the combined effects of anthropogenic noise and Cd on the physiological characteristics of the blood clam Tegillarca granosa were investigated in this study. The results showed that 10 days of coexposure to anthropogenic noise and Cd can enhance adverse impacts on metabolic processes, as indicated by the clearance rate, respiration rate, ammonium excretion rate, and O:N ratio of T. granosa. In addition, both the ATP content, ATP synthase activity and genes encoding important enzymes in ATP synthesis significantly declined after coexposures to anthropogenic noise and Cd, which have resulted from reduced feeding activity and respiration. Furthermore, the expressions of neurotransmitter-related genes (MAO, AChE, and mAChR3) were all significantly down-regulated after coexposure to anthropogenic noise and Cd, which suggests an enhanced neurotoxicity under coexposure. In conclusion, our study demonstrated that anthropogenic noise and Cd would have synergetic effects on the feeding activity, metabolism, and ATP synthesis of T. granosa, which may be due to the add-on of stress responses and neurotransmitter disturbances.
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Affiliation(s)
- Wei Shi
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Yu Han
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Xiaofan Guan
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Jiahuan Rong
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Xueying Du
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Shanjie Zha
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Yu Tang
- College of Animal Science, Zhejiang University, Hangzhou, China
| | - Guangxu Liu
- College of Animal Science, Zhejiang University, Hangzhou, China
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Guan X, Shi W, Zha S, Rong J, Su W, Liu G. Neurotoxic impact of acute TiO 2 nanoparticle exposure on a benthic marine bivalve mollusk, Tegillarca granosa. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 200:241-246. [PMID: 29778933 DOI: 10.1016/j.aquatox.2018.05.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 05/11/2018] [Accepted: 05/14/2018] [Indexed: 06/08/2023]
Abstract
The release of nanoparticles (NPs) into the ocean inevitably poses a threat to marine organisms. However, to date, the neurotoxic effects of NPs remains poorly understood in marine bivalve species. Therefore, in order to gain a better understanding of the physiological effects of NPs, the impact of acute (96 h) TiO2 NP exposure on the in vivo concentrations of three major neurotransmitters, the activity of AChE, and the expression of neurotransmitter-related genes was investigated in the blood clam, Tegillarca granosa. The obtained results showed that the in vivo concentrations of the three tested neurotransmitters (DA, GABA, and ACh) were significantly increased when exposed to relatively high doses of TiO2 NPs (1 mg/L for DA and 10 mg/L for ACh and GABA). Additionally, clams exposed to seawater contaminated with TiO2 NP had significantly lower AChE activity. In addition, the expression of genes encoding modulatory enzymes (AChE, GABAT, and MAO) and receptors (mAChR3, GABAD, and DRD3) for the neurotransmitters tested were all significantly down-regulated after TiO2 NP exposure. Therefore, this study has demonstrated the evident neurotoxic impact of TiO2 NPs in T. granosa, which may have significant consequences for a number of the organism's physiological processes.
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Affiliation(s)
- Xiaofan Guan
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China
| | - Wei Shi
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China
| | - Shanjie Zha
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China
| | - Jiahuan Rong
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China
| | - Wenhao Su
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China
| | - Guangxu Liu
- College of Animal Science, Zhejiang University, Hangzhou, 310058, China.
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8
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Wang R. Physiological implications of hydrogen sulfide: a whiff exploration that blossomed. Physiol Rev 2012; 92:791-896. [PMID: 22535897 DOI: 10.1152/physrev.00017.2011] [Citation(s) in RCA: 1371] [Impact Index Per Article: 114.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The important life-supporting role of hydrogen sulfide (H(2)S) has evolved from bacteria to plants, invertebrates, vertebrates, and finally to mammals. Over the centuries, however, H(2)S had only been known for its toxicity and environmental hazard. Physiological importance of H(2)S has been appreciated for about a decade. It started by the discovery of endogenous H(2)S production in mammalian cells and gained momentum by typifying this gasotransmitter with a variety of physiological functions. The H(2)S-catalyzing enzymes are differentially expressed in cardiovascular, neuronal, immune, renal, respiratory, gastrointestinal, reproductive, liver, and endocrine systems and affect the functions of these systems through the production of H(2)S. The physiological functions of H(2)S are mediated by different molecular targets, such as different ion channels and signaling proteins. Alternations of H(2)S metabolism lead to an array of pathological disturbances in the form of hypertension, atherosclerosis, heart failure, diabetes, cirrhosis, inflammation, sepsis, neurodegenerative disease, erectile dysfunction, and asthma, to name a few. Many new technologies have been developed to detect endogenous H(2)S production, and novel H(2)S-delivery compounds have been invented to aid therapeutic intervention of diseases related to abnormal H(2)S metabolism. While acknowledging the challenges ahead, research on H(2)S physiology and medicine is entering an exponential exploration era.
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Affiliation(s)
- Rui Wang
- Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada.
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Robbins HM, Bricelj VM, Ward JE. In vivo effects of brown tide on the feeding function of the gill of the northern quahog Mercenaria mercenaria (Bivalvia: Veneridae). THE BIOLOGICAL BULLETIN 2010; 219:61-71. [PMID: 20813990 DOI: 10.1086/bblv219n1p61] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The in vivo response of adult northern quahogs, Mercenaria mercenaria, to Aureococcus anophagefferens (brown tide) at the level of the gill was determined using video-endoscopy. Feeding activity, particle-approach velocities, and ventral-groove-transport velocities were documented after the quahogs were exposed to Isochryis galbana (baseline observations) supplemented with either toxic or nontoxic A. anophagefferens at two bloom concentrations (8 x 10(5) or 2 x 10(6) cells ml(-1)). Externally, there was no evidence of adverse effects of brown tide on feeding, as siphons remained extended and dilated. Toxic brown tide at both concentrations elicited gill muscular contractions, intermittent cessation of water flow, and decreased particle loading within the pallial cavity. The 8 x 10(5) cell ml(-1) toxic treatment had no significant effect on approach velocities or ventral-groove-transport velocities after 2 h, although time-averaging showed significant reduction of the latter during the last 30 min of exposure. The higher concentration of toxic brown tide caused a significant decrease in these velocities after only 1 h. Nontoxic brown tide produced none of these effects. Thus, A. anophagefferens compromised quahog feeding by stimulating contractions of the branchial musculature and interfering with lateral and ventral groove ciliary beating. These effects were both time- and concentration-dependent and could be caused by either a dopaminergic or a serotonergic toxic factor.
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Affiliation(s)
- Heather M Robbins
- National Research Council, Institute for Marine Biosciences, NS B3H 3Z1, Canada.
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Gainey LF. Seasonal control of particle clearance by isolated gills from the clam Mercenaria mercenaria. J Exp Biol 2007; 210:2518-25. [PMID: 17601956 DOI: 10.1242/jeb.005637] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Pieces of gill isolated from the clam Mercenaria mercenaria clear colloidal graphite from seawater, and the clearance rates are measurable. 5-Hydroxytryptamine (5-HT) had a biphasic effect on clearance rates:concentrations from 10–6 to 10–5 mol l–1 5-HT increased clearance, but higher concentrations reduced it. During the summer, the gills were less responsive to 5-HT: the threshold increased from 1×10–6 to 5×10–6 mol l–1, and although the rate was still maximal at 10–5 mol l–1, it was significantly lower than the maximal rate in the winter. At 10–5 mol l–1 5-HT, which maximized clearance, the lateral cilia were active, the interfilament space decreased and the diameter of the water tubes increased. Higher concentrations of 5-HT contracted the gill musculature, which inhibited the lateral cilia, decreased the interfilament space even more and decreased the diameter of the water tubes. The nitric oxide (NO) generator DEANO stimulated clearance in the winter but had no effect during the summer. l-NAME, an inhibitor of NO synthesis, diminished the effect of 5-HT during the winter but was ineffective during the summer. The diminished response to 5-HT of winter gills treated with l-NAME was statistically equal to the response of the gills to 5-HT during the summer. Dopamine (DA) inhibited clearance, and the gills were more sensitive to DA in winter than in summer. Microscopic examination of untreated gills revealed little or no lateral ciliary activity,and clearance was minimal. Thus, clearance rates of isolated gills behave in a manner consistent with the seasonality and pharmacology of the lateral cilia and branchial musculature.
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Affiliation(s)
- Louis F Gainey
- Department of Biological Sciences, The University of Southern Maine, Portland, ME 04104, USA.
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11
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Nitric oxide biogenesis, signalling and roles in molluscs: The Sepia officinalis paradigm. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/s1872-2423(07)01002-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Gainey LF, Greenberg MJ. Hydrogen sulfide is synthesized in the gills of the clam Mercenaria mercenaria and acts seasonally to modulate branchial muscle contraction. THE BIOLOGICAL BULLETIN 2005; 209:11-20. [PMID: 16110090 DOI: 10.2307/3593138] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Previously we showed that when the gill muscles of the venerid clam Mercenaria mercenaria are stimulated to contract by 5-hydroxytryptamine (5HT), the contraction is about doubled when another identical dose of 5HT is applied after washout. Furthermore, this "endogenous potentiation" is mimicked by nitric oxide (NO), which is synthesized in the gill. We now report that the isolated gills also synthesize H2S; the basal rate of synthesis was 0.70 micromol.g(-1).h(-1) (se = 0.14; n = 24), but in the presence of 5HT (10(-2) M), the rate increased markedly to 35.82 micromol.g(-1).h(-1) (se = 4.93; n = 4). In addition, dithiothreitol (DTT; 2.2 mM) increased the rate of synthesis significantly to 4.9 micromol.g(-1).h(-1) (se = 0.8; n = 8). Stimulation of H2S synthesis by 5HT (5 x 10(-3) M) was seasonal; that is, the rates measured monthly from December through June are significantly lower than those measured from July through November. We also found that if isolated gills were pretreated with the H2S donor, sodium hydrosulfide (NaHS), their contractions in response to 5HT were potentiated. The threshold of the potentiation was 10(-8) M NaHS, and the largest effect was at 10(-6) M. During August, however, when endogenous and NO-induced potentiations are both absent, 10(-6) M NaHS was also ineffective. Like the effect of NO, that of NaHS (10(-6) M) was blocked by oxadiasoloquinoxalin (ODQ; 5 x 10(-5) M), an inhibitor of soluble guanylate cyclase (sGC). Moreover, Rp-8-CPT-cGMPS (10(-5) M), which inhibits protein kinase-G, also blocked the effect of NaHS (10(-6) M). When isolated gills were treated with 2.2 mM DTT, the endogenous potentiation of a second 5HT-induced contraction more than doubled in comparison to untreated controls. In conclusion, H2S is synthesized in the gill and, along with NO, is a seasonal, endogenous modulator of branchial muscle contraction; its action may be mediated through a sGC/cGMP signaling cascade.
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Affiliation(s)
- Louis F Gainey
- Department of Biological Sciences, University of Southern Maine, Portland, Maine 04104, USA.
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