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Pan YK. Structure and function of the larval teleost fish gill. J Comp Physiol B 2024:10.1007/s00360-024-01550-8. [PMID: 38584182 DOI: 10.1007/s00360-024-01550-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/05/2024] [Accepted: 03/25/2024] [Indexed: 04/09/2024]
Abstract
The fish gill is a multifunctional organ that is important in multiple physiological processes such as gas transfer, ionoregulation, and chemoreception. This characteristic organ of fishes has received much attention, yet an often-overlooked point is that larval fishes in most cases do not have a fully developed gill, and thus larval gills do not function identically as adult gills. In addition, large changes associated with gas exchange and ionoregulation happen in gills during the larval phase, leading to the oxygen and ionoregulatory hypotheses examining the environmental constraint that resulted in the evolution of gills. This review thus focuses exclusively on the larval fish gill of teleosts, summarizing the development of teleost larval fish gills and its function in gas transfer, ionoregulation, and chemoreception, and comparing and contrasting it to adult gills where applicable, while providing some insight into the oxygen vs ionoregulatory hypotheses debate.
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Affiliation(s)
- Yihang Kevin Pan
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
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2
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Tea M, Pan YK, Lister JGR, Perry SF, Gilmour KM. Effects of serta and sertb knockout on aggression in zebrafish (Danio rerio). J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2024:10.1007/s00359-024-01693-7. [PMID: 38416162 DOI: 10.1007/s00359-024-01693-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 01/12/2024] [Accepted: 02/01/2024] [Indexed: 02/29/2024]
Abstract
Zebrafish (Danio rerio) are unusual in having two paralogues of the serotonin re-uptake transporter (Sert), slc6a4a (serta) and slc6a4b (sertb), the transporter that serves in serotonin re-uptake from a synapse into the pre-synaptic cell or in serotonin uptake from the extracellular milieu into cells in the peripheral tissues. To address a knowledge gap concerning the specific roles of these paralogues, we used CRISPR/Cas9 technology to generate zebrafish knockout lines predicted to lack functional expression of Serta or Sertb. The consequences of loss-of-function of Serta or Sertb were assessed at the gene expression level, focusing on the serotonergic signalling pathway, and at the behaviour level, focusing on aggression. Whereas serta mRNA was expressed in all tissues examined, with high expression in the heart, gill and brain, only the brain displayed substantial sertb mRNA expression. In both serta-/- and sertb-/- fish, changes in transcript abundances of multiple components of the serotonin signalling pathway were detected, including proteins involved in serotonin synthesis (tph1a, tph1b, tph2, ddc), packaging (vmat2) and degradation (mao), and serotonin receptors (htr1aa, htr1ab). Using a mirror aggression test, serta-/- male but not female fish exhibited greater aggression than wildtype fish. However, both male and female sertb-/- fish displayed less aggression than their wildtype counterparts. These differences in behaviour between serta-/- and sertb-/- individuals hold promise for increasing our understanding of the neurophysiological basis of aggression in zebrafish.
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Affiliation(s)
- Michael Tea
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt, Ottawa, ON, K1N 6N5, Canada
| | - Yihang Kevin Pan
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt, Ottawa, ON, K1N 6N5, Canada
| | - Joshua G R Lister
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt, Ottawa, ON, K1N 6N5, Canada
| | - Steve F Perry
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt, Ottawa, ON, K1N 6N5, Canada
| | - Kathleen M Gilmour
- Department of Biology, University of Ottawa, 30 Marie Curie Pvt, Ottawa, ON, K1N 6N5, Canada.
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Kämmer N, Reimann T, Braunbeck T. Neurotoxic pesticides change respiratory parameters in early gill-breathing, but not in skin-breathing life-stages of zebrafish (Danio rerio). AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2024; 267:106831. [PMID: 38244448 DOI: 10.1016/j.aquatox.2024.106831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/31/2023] [Accepted: 01/07/2024] [Indexed: 01/22/2024]
Abstract
Neurotoxic compounds can interfere with active gill ventilation in fish, which might lead to premature death in adult fish, but not in skin-breathing embryos of zebrafish, since these exclusively rely on passive diffusion across the skin. Regarding lethality, this respiratory failure syndrome (RFS) has been discussed as one of the main reasons for the higher sensitivity of adult fish in the acute fish toxicity test (AFT), if compared to embryos in the fish embryo toxicity test (FET). To further elucidate the relationship between the onset of gill respiration and death by a neurotoxic mode of action, a comparative study into oxygen consumption (MO2), breathing frequency (fv) and amplitude (fampl) was performed with 4 d old skin-breathing and 12 d old early gill-breathing zebrafish. Neurotoxic model substances with an LC50 FET/AFT ratio of > 10 were used: chlorpyrifos, permethrin, aldicarb, ziram, and fluoxetine. Exposure to hypoxia served as a positive control, whereas aniline was tested as an example of a narcotic substance interfering non-specifically with gill membranes. In 12 d old larvae, all substances caused an increase in MO2, fv and partly fampl, whereas effects were minor in 4 d old embryos. An increase of fv in 4 d old embryos following exposure to chlorpyrifos, aldicarb and hypoxia could not be correlated with an increased MO2 and might be attributed either to (1) to the successfully postponed decrease of arterial partial pressure of oxygen (PO2) through support of skin respiration by increased fv, (2) to an unspecific stimulation of the sphincter muscles at the base of the gill filaments, or (3) to the establishment of oxygen sensing for later stages. In gill-breathing 12 d old zebrafish, a concentration-dependent increase of fv was detected for aniline and chlorpyrifos, whereas for aldicarb, fluoxetine and permethrin, a decline of fv at higher substance concentrations was measured, most likely due to the onset of paralysis and/or fatigue of the gill filament sphincter muscles. Since alterations of fv serve to postpone the decrease in arterial PO2 and MO2 increased with decreasing fv, the respiratory failure syndrome could clearly be demonstrated in 12 d old zebrafish larvae. Passive respiration across the skin in zebrafish embryos could thus be confirmed as a probable reason for the lower sensitivity of early life-stages to neurotoxicants. Integration of respiratory markers into existing testing protocols with non-protected developmental stages such as embryos might help to not underestimate the toxicity of early life-stages of fish.
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Affiliation(s)
- Nadine Kämmer
- Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69210, Heidelberg, Germany.
| | - Tanja Reimann
- Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69210, Heidelberg, Germany
| | - Thomas Braunbeck
- Aquatic Ecology and Toxicology Section, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 504, D-69210, Heidelberg, Germany.
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Pan YK, Perry SF. The control of breathing in fishes - historical perspectives and the path ahead. J Exp Biol 2023; 226:307288. [PMID: 37097020 DOI: 10.1242/jeb.245529] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
The study of breathing in fishes has featured prominently in Journal of Experimental Biology (JEB), particularly during the latter half of the past century. Indeed, many of the seminal discoveries in this important sub-field of comparative respiratory physiology were reported first in JEB. The period spanning 1960-1990 (the 'golden age of comparative respiratory physiology') witnessed intense innovation in the development of methods to study the control of breathing. Many of the guiding principles of piscine ventilatory control originated during this period, including our understanding of the dominance of O2 as the driver of ventilation in fish. However, a critical issue - the identity of the peripheral O2 chemoreceptors - remained unanswered until methods for cell isolation, culture and patch-clamp recording established that gill neuroepithelial cells (NECs) respond to hypoxia in vitro. Yet, the role of the NECs and other putative peripheral or central chemoreceptors in the control of ventilation in vivo remains poorly understood. Further progress will be driven by the implementation of genetic tools, most of which can be used in zebrafish (Danio rerio). These tools include CRISPR/Cas9 for selective gene knockout, and Tol2 systems for transgenesis, the latter of which enables optogenetic stimulation of cellular pathways, cellular ablation and in vivo cell-specific biosensing. Using these methods, the next period of discovery will see the identification of the peripheral sensory pathways that initiate ventilatory responses, and will elucidate the nature of their integration within the central nervous system and their link to the efferent motor neurons that control breathing.
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Affiliation(s)
- Yihang Kevin Pan
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
| | - Steve F Perry
- Department of Biology, University of Ottawa, Ottawa, ON, Canada, K1N 6N5
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Perry SF, Pan YK, Gilmour KM. Insights into the control and consequences of breathing adjustments in fishes-from larvae to adults. Front Physiol 2023; 14:1065573. [PMID: 36793421 PMCID: PMC9923008 DOI: 10.3389/fphys.2023.1065573] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
Adjustments of ventilation in fishes to regulate the volume of water flowing over the gills are critically important responses to match branchial gas transfer with metabolic needs and to defend homeostasis during environmental fluctuations in O2 and/or CO2 levels. In this focused review, we discuss the control and consequences of ventilatory adjustments in fish, briefly summarizing ventilatory responses to hypoxia and hypercapnia before describing the current state of knowledge of the chemoreceptor cells and molecular mechanisms involved in sensing O2 and CO2. We emphasize, where possible, insights gained from studies on early developmental stages. In particular, zebrafish (Danio rerio) larvae have emerged as an important model for investigating the molecular mechanisms of O2 and CO2 chemosensing as well as the central integration of chemosensory information. Their value stems, in part, from their amenability to genetic manipulation, which enables the creation of loss-of-function mutants, optogenetic manipulation, and the production of transgenic fish with specific genes linked to fluorescent reporters or biosensors.
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Kevin Pan Y, Julian T, Garvey K, Perry SF. Catecholamines modulate the hypoxic ventilatory response of larval zebrafish (Danio rerio). J Exp Biol 2023; 226:286267. [PMID: 36484145 DOI: 10.1242/jeb.245051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022]
Abstract
The hypoxic ventilatory response (HVR) in fish is an important reflex that aids O2 uptake when low environmental O2 levels constrain diffusion. In developing zebrafish (Danio rerio), the acute HVR is multiphasic, consisting of a rapid increase in ventilation frequency (fV) during hypoxia onset, followed by a decline to a stable plateau phase above fV under normoxic conditions. In this study, we examined the potential role of catecholamines in contributing to each of these phases of the dynamic HVR in zebrafish larvae. We showed that adrenaline elicits a dose-dependent β-adrenoreceptor (AR)-mediated increase in fV that does not require expression of β1-ARs, as the hyperventilatory response to β-AR stimulation was unaltered in adrb1-/- mutants, generated by CRISPR/Cas9 knockout. In response to hypoxia and propranolol co-treatment, the magnitude of the rapidly occurring peak increase in fV during hypoxia onset was attenuated (112±14 breaths min-1 without propranolol to 68±17 breaths min-1 with propranolol), whereas the increased fV during the stable phase of the HVR was prevented in both wild type and adrb1-/- mutants. Thus, β1-AR is not required for the HVR and other β-ARs, although not required for initiation of the HVR, are involved in setting the maximal increase in fV and in maintaining hyperventilation during continued hypoxia. This adrenergic modulation of the HVR may arise from centrally released catecholamines because adrenaline exposure failed to activate (based on intracellular Ca2+ levels) cranial nerves IX and X, which transmit O2 signals from the pharyngeal arch to the central nervous system.
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Affiliation(s)
- Yihang Kevin Pan
- Department of Biology, University of Ottawa, ON, Canada, K1N 9A7
| | - Tess Julian
- Department of Biology, University of Ottawa, ON, Canada, K1N 9A7
| | - Kayla Garvey
- Department of Biology, University of Ottawa, ON, Canada, K1N 9A7
| | - Steve F Perry
- Department of Biology, University of Ottawa, ON, Canada, K1N 9A7
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Santos D, Luzio A, Félix L, Bellas J, Monteiro SM. Oxidative stress, apoptosis and serotonergic system changes in zebrafish (Danio rerio) gills after long-term exposure to microplastics and copper. Comp Biochem Physiol C Toxicol Pharmacol 2022; 258:109363. [PMID: 35525464 DOI: 10.1016/j.cbpc.2022.109363] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/28/2022] [Accepted: 05/01/2022] [Indexed: 02/06/2023]
Abstract
Fish gills are in direct contact with the surrounding pollutants, and thus, potentially more vulnerable to microplastics (MPs) and heavy metals. The present study aimed to evaluate the long-term exposure effects of MPs and copper (Cu) in the gills of adult zebrafish (Danio rerio). To this end, zebrafish were exposed to MPs (2 mg/L), Cu (Cu25, 25 μg/L) and their mixture (Cu25 + MPs) for 30 days, and then oxidative stress, detoxification, antioxidant, metabolic and neurotoxicity enzymes/genes, as well serotonergic system and apoptosis genes, were evaluated in gills. In the mixture group, ROS levels were increased, while CAT and GPx activities were inhibited, indicating the induction of oxidative stress in zebrafish gills. This was followed by an increase of LPO levels and potential oxidative damage in zebrafish gills. The tryptophan hydroxylase 1a (tph1a) and caspase-3 (casp3) genes were significantly upregulated in Cu25 + MPs group, indicating a potential dysregulation of serotonin synthesis and apoptosis pathways, respectively. Overall, the present study contributes to improving the knowledge about the response of aquatic organisms to MPs and the potential ecological risk that these particles represent to the ecosystems.
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Affiliation(s)
- Dércia Santos
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal.
| | - Ana Luzio
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal
| | - Luís Félix
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal
| | - Juan Bellas
- Centro Oceanográfico de Vigo, Instituto Español de Oceanografía, IEO-CSIC, Subida a Radio Faro 50, 36390 Vigo, Spain
| | - Sandra M Monteiro
- Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal; Inov4Agro, Institute for Innovation, Capacity Building and Sustainability of Agri-food Production, Portugal
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Single-cell transcriptomic analysis of neuroepithelial cells and other cell types of the gills of zebrafish (Danio rerio) exposed to hypoxia. Sci Rep 2022; 12:10144. [PMID: 35710785 PMCID: PMC9203529 DOI: 10.1038/s41598-022-13693-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 05/26/2022] [Indexed: 12/21/2022] Open
Abstract
The fish gill is a multifunctional organ involved in numerous physiological processes, such as gas exchange and sensing of hypoxia by respiratory chemoreceptors, called neuroepithelial cells (NECs). Many studies have focused on zebrafish (Danio rerio) to investigate the structure, function and development of the gills, yet the transcriptomic profile of most gill cells remains obscure. We present the results of a comprehensive transcriptomic analysis of the gills of zebrafish using single-cell RNA sequencing (scRNA‐seq). Gill cells from ETvmat2:EGFP zebrafish were individually labelled before scRNA‐seq library construction using 10× Genomics Chromium technology. 12,819 cells were sequenced with an average depth of over 27,000 reads per cell. We identified a median of 485 genes per cell and 16 cell clusters, including NECs, neurons, pavement cells, endothelial cells and mitochondrion-rich cells. The identity of NECs was confirmed by expression of slc18a2, encoding the vesicular monoamine transporter, Vmat2. Highly differentially-expressed genes in NECs included tph1a, encoding tryptophan hydroxylase, sv2 (synaptic vesicle protein), and proteins implicated in O2 sensing (ndufa4l2a, cox8al and epas1a). In addition, NECs and neurons expressed genes encoding transmembrane receptors for serotonergic, cholinergic or dopaminergic neurotransmission. Differential expression analysis showed a clear shift in the transcriptome of NECs following 14 days of acclimation to hypoxia. NECs in the hypoxia group showed high expression of genes involved in cell cycle control and proliferation. The present article provides a complete cell atlas for the zebrafish gill and serves as a platform for future studies investigating the molecular biology and physiology of this organ.
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Cinelli E. Prelude Special Issue: Breathing and Evolution. Respir Physiol Neurobiol 2021; 297:103832. [PMID: 34958947 DOI: 10.1016/j.resp.2021.103832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Elenia Cinelli
- Dipartimento di Medicina Sperimentale e Clinica, Sezione Scienze Fisiologiche, Università degli Studi di Firenze, Viale G.B. Morgagni 63, 50134, Firenze, Italy.
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Baronio D, Chen YC, Panula P. Abnormal brain development of monoamine oxidase mutant zebrafish and impaired social interaction of heterozygous fish. Dis Model Mech 2021; 15:273667. [PMID: 34881779 PMCID: PMC8891935 DOI: 10.1242/dmm.049133] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 12/01/2021] [Indexed: 11/20/2022] Open
Abstract
Monoamine oxidase (MAO) deficiency and imbalanced levels of brain monoamines have been associated with developmental delay, neuropsychiatric disorders and aggressive behavior. Animal models are valuable tools to gain mechanistic insight into outcomes associated with MAO deficiency. Here, we report a novel genetic model to study the effects of mao loss of function in zebrafish. Quantitative PCR, in situ hybridization and immunocytochemistry were used to study neurotransmitter systems and expression of relevant genes for brain development in zebrafish mao mutants. Larval and adult fish behavior was evaluated through different tests. Stronger serotonin immunoreactivity was detected in mao+/− and mao−/− larvae compared with their mao+/+ siblings. mao−/− larvae were hypoactive, and presented decreased reactions to visual and acoustic stimuli. They also had impaired histaminergic and dopaminergic systems, abnormal expression of developmental markers and died within 20 days post-fertilization. mao+/− fish were viable, grew until adulthood, and demonstrated anxiety-like behavior and impaired social interactions compared with adult mao+/+ siblings. Our results indicate that mao−/− and mao+/− mutants could be promising tools to study the roles of MAO in brain development and behavior. This article has an associated First Person interview with the first author of the paper. Summary: We assessed developmental, neurochemical and behavioral alterations displayed by mao+/− and mao−/− zebrafish, establishing that these model organisms are promising tools to study the consequences of MAOA/B deficiency.
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Affiliation(s)
- Diego Baronio
- Department of Anatomy, University of Helsinki, Helsinki, Finland
| | - Yu-Chia Chen
- Department of Anatomy, University of Helsinki, Helsinki, Finland
| | - Pertti Panula
- Department of Anatomy, University of Helsinki, Helsinki, Finland
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