Structural Identification of the Pacemaker Cells and Expression of Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channels in the Heart of the Wild Atlantic Cod, Gadus morhua (Linnaeus, 1758)

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are proteins that contain highly conserved functional domains and sequence motifs that are correlated with their unique biophysical activities, to regulate cardiac pacemaker activity and synaptic transmission. These pacemaker proteins have been studied in mammalian species, but little is known now about their heart distribution in lower vertebrates and c-AMP modulation. Here, we characterized the pacemaker system in the heart of the wild Atlantic cod (Gadus morhua), with respect to primary pacemaker molecular markers. Special focus is given to the structural, ultrastructural and molecular characterization of the pacemaker domain, through the expression of HCN channel genes and the immunohistochemistry of HCN isoforms, including the location of intracardiac neurons that are adjacent to the sinoatrial region of the heart. Similarly to zebrafish and mammals, these neurons are immunoreactive to ChAT, VAChT and nNOS. It has been shown that cardiac pacemaking can be modulated by sympathetic and parasympathetic pathways, and the existence of intracardiac neurons projecting back to the central nervous system provide a plausible link between them.

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Zebrafish heart as a model to study the integrative autonomic control of pacemaker function

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00330.2016 ◽

2016 ◽

Vol 311 (3) ◽

pp. H676-H688 ◽

Cited By ~ 21

Author(s):

Matthew R. Stoyek ◽

T. Alexander Quinn ◽

Roger P. Croll ◽

Frank M. Smith

Keyword(s):

Nerve Stimulation ◽

Mammalian Species ◽

Cardiac Pacemaker ◽

Autonomic Control ◽

Pacemaker Activity ◽

Pacemaker Cells ◽

Physiological Control ◽

Adrenergic Agents ◽

Zebrafish Heart ◽

Stimulation Of

The cardiac pacemaker sets the heart's primary rate, with pacemaker discharge controlled by the autonomic nervous system through intracardiac ganglia. A fundamental issue in understanding the relationship between neural activity and cardiac chronotropy is the identification of neuronal populations that control pacemaker cells. To date, most studies of neurocardiac control have been done in mammalian species, where neurons are embedded in and distributed throughout the heart, so they are largely inaccessible for whole-organ, integrative studies. Here, we establish the isolated, innervated zebrafish heart as a novel alternative model for studies of autonomic control of heart rate. Stimulation of individual cardiac vagosympathetic nerve trunks evoked bradycardia (parasympathetic activation) and tachycardia (sympathetic activation). Simultaneous stimulation of both vagosympathetic nerve trunks evoked a summative effect. Effects of nerve stimulation were mimicked by direct application of cholinergic and adrenergic agents. Optical mapping of electrical activity confirmed the sinoatrial region as the site of origin of normal pacemaker activity and identified a secondary pacemaker in the atrioventricular region. Strong vagosympathetic nerve stimulation resulted in a shift in the origin of initial excitation from the sinoatrial pacemaker to the atrioventricular pacemaker. Putative pacemaker cells in the sinoatrial and atrioventricular regions expressed adrenergic β2 and cholinergic muscarinic type 2 receptors. Collectively, we have demonstrated that the zebrafish heart contains the accepted hallmarks of vertebrate cardiac control, establishing this preparation as a viable model for studies of integrative physiological control of cardiac function by intracardiac neurons.

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Effects of temperature on life history set the sensitivity to fishing in Atlantic cod Gadus morhua

Marine Ecology Progress Series ◽

10.3354/meps10943 ◽

2014 ◽

Vol 514 ◽

pp. 217-229 ◽

Cited By ~ 11

Author(s):

HY Wang ◽

LW Botsford ◽

JW White ◽

MJ Fogarty ◽

F Juanes ◽

...

Keyword(s):

Life History ◽

Gadus Morhua ◽

Atlantic Cod ◽

Effects Of Temperature

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Responses of Atlantic cod Gadus morhua head kidney leukocytes to phytase produced by gastrointestinal-derived bacteria

Fish Physiology and Biochemistry ◽

10.1007/s10695-009-9364-0 ◽

2009 ◽

Vol 36 (4) ◽

pp. 883-891 ◽

Cited By ~ 14

Author(s):

Carlo C. Lazado ◽

Christopher Marlowe A. Caipang ◽

Sanchala Gallage ◽

Monica F. Brinchmann ◽

Viswanath Kiron

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Head Kidney

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Some recent data on sperm morphology and motility kinetics in Atlantic cod (Gadus morhua L.)

Fish Physiology and Biochemistry ◽

10.1007/s10695-020-00915-4 ◽

2021 ◽

Author(s):

Sayyed Mohammad Hadi Alavi ◽

Azadeh Hatef ◽

Ian A.E. Butts ◽

Olga Bondarenko ◽

Jacky Cosson ◽

...

Keyword(s):

Gadus Morhua ◽

Sperm Morphology ◽

Atlantic Cod

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Natural mortality from poor condition in Atlantic cod (Gadus morhua)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-023 ◽

2000 ◽

Vol 57 (4) ◽

pp. 826-836 ◽

Cited By ~ 96

Author(s):

Jean-Denis Dutil ◽

Yvan Lambert

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Negative Impact ◽

Fish Muscle ◽

Early Summer ◽

Wild Fish ◽

Natural Mortality ◽

Muscle Lactate ◽

Lactate Dehydrogenase Activity ◽

Poor Condition

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

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