S.f. Perry

• Doctor of Philosophy
• Professor (Full) at University of Ottawa

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 knowledg...

Adrenaline and noradrenaline, released as hormones and/or neurotransmitters, exert diverse physiological functions in vertebrates, and teleost fishes are widely used as model organisms to study adrenergic regulation; however, such investigations often rely on receptor subtype-specific pharmacological agents (agonists and antagonists; see Glossary)...

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 comparati...

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 adjust...

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...

Ammonia excretion in fish excretory epithelia is a complex interplay of multiple membrane transport proteins and mechanisms. Using the model system of zebrafish (Danio rerio) larvae, here we identified three paralogues of a novel ammonia transporter, hippocampus abundant transcript 1 (DrHIAT1), found also in most vertebrates. When functionally expr...

The sensing of environmental fluctuations and initiation of appropriate physiological responses is crucial to homeostasis. Neuroepithelial cells (NECs) in fishes are putative chemoreceptors that respond in vitro to changes in O 2 , CO 2 , NH 3 and pH. Cytosolic carbonic anhydrase (Ca17a) is thought to be involved in CO 2 sensing owing to its presen...

Aim: Although zebrafish are gaining popularity as biomedical models of cardiovascular disease, our understanding of their cardiac control mechanisms is fragmentary. Our goal was to clarify the controversial role of the ß1-adrenergic receptor (AR) in the regulation of heart rate in zebrafish. Methods: CRISPR-Cas9 was used to delete the adrb1 gene...

Fish aquaculture facilities strive to maintain abiotic conditions that optimise somatic growth. Two physiological systems that are critically linked to environmental abiotic factors are ion and acid‐base regulation. Given the detrimental effects of ionic and acid‐base imbalances coupled with the potential energetic costs of ion and acid‐base regula...

Hypoxia-inducible factor 1-α (Hif-1α), an important transcription factor regulating cellular responses to reductions in O 2 , previously was shown to improve hypoxia tolerance in zebrafish ( Danio rerio ). Here, we examined the contribution of Hif-1α to hypoxic survival, focusing on the benefit of aquatic surface respiration (ASR). Wild-type and Hi...

The hypoxia-inducible factor (HIF) pathway is a key regulator of cellular O2 homeostasis and an important orchestrator of the physiological responses to hypoxia (low O2) in vertebrates. Fish can be exposed to significant and frequent changes in environmental O2, and increases in Hif-α (the hypoxia-sensitive subunit of the transcription factor Hif)...

In the current study, adult zebrafish (Danio rerio) were exposed to 72 h hypoxia (90 mmHg) to assess the time domains of the hypoxia ventilatory response (HVR) and the consequence on a subsequent more severe (40 mmHg) bout of acute hypoxia. Experiments were performed on wild-type fish and mutants in which one or both paralogs of hypoxia inducible f...

Previous studies have demonstrated that hypoxia tolerance is improved in zebrafish (Danio rerio) larvae after prior exposure to lowered ambient O2 levels. Such improved hypoxia performance was attributed in part, to increased levels of hypoxia-inducible factor 1α (Hif-1α) exerting downstream effects on various physiological processes including prom...

The tambaqui (Colossoma macropomum), migrates annually between whitewater and blackwater rivers of the Amazon. Unlike the whitewater, blackwater is characterized by higher levels of dissolved organic carbon (DOC), including humic acids (HA). Because humic substances impair sensory processes, the current study tested the hypothesis that O2 and/or CO...

The effects of high external ammonia (HEA) exposure on breathing and the potential involvement of ammonia transporting Rh proteins in ammonia sensing were assessed in larval and adult zebrafish. Acute exposure of adults to either 250 or 500 μM (NH4)2SO4 caused increases in ventilation amplitude (AVENT) without affecting frequency (fVENT), resemblin...

In fishes, branchial cytosolic carbonic anhydrase (CA) plays an important role in ion and acid-base regulation. The Ca17a isoform in zebrafish (Danio rerio) is expressed abundantly in Na ⁺ -absorbing/H ⁺ -secreting H ⁺ -ATPase-rich (HR) cells. The present study aimed to identify the role of Ca17a in ion and acid-base regulation across life stages u...

In zebrafish (Danio rerio), a specific ionocyte subtype, the H ⁺ -ATPase-rich (HR) cell, is presumed to be a significant site of transepithelial Na ⁺ uptake/acid-secretion. During acclimation to environments differing in ionic composition or pH, ionic and acid-base regulation are achieved by adjustments to the activity level of HR cell ion transpor...

Fishes living in fresh water counter the passive loss of salts by actively absorbing ions through specialized cells termed ionocytes. Ionocytes contain ATP-dependent transporters, are enriched with mitochondria, and therefore ionic regulation is an energy-consuming process. The purpose of this study was to assess the aerobic costs of ion transport...

The coordination of the hypoxic response is attributed, in part, to hypoxia-inducible factor 1α (Hif-1α), a regulator of hypoxia-induced transcription. After the teleost-specific genome duplication, most teleost fishes lost the duplicate copy of Hif-1α, except species in the cyprinid lineage that retained both paralogues of Hif-1α (Hif1aa and Hif1a...

In zebrafish (Danio rerio), the ammonia-transporting Rhesus glycoprotein Rhcgb is implicated in mechanisms of ammonia excretion and Na⁺ uptake. In particular, Rhcgb is thought to play an important role in maintaining ammonia excretion in response to alkaline conditions and high external ammonia (HEA) exposure, in addition to facilitating Na⁺ uptake...

Fish increase ventilation during hypoxia, a reflex termed the hypoxic ventilatory response (HVR). The HVR is an effective mechanism to increase O2 uptake, but at a high metabolic cost. Therefore, when hypoxia becomes severe enough, ventilation declines, as its benefit is diminished. The water oxygen partial pressure (PwO2) at which this decline occ...

The H+-ATPase rich (HR) cells of zebrafish larvae are a sub-type of ion-transporting cell located on the yolk sac epithelium that are responsible for Na+ uptake and H+ extrusion. Current models of HR cell ion transport mechanisms in zebrafish larvae are well established, but little is known about the involvement of the various ion transport pathway...

Freshwater fishes absorb Na+ from their dilute environment using ion-transporting cells. In larval zebrafish (Danio rerio), Na+ uptake is coordinated by (1) Na+/H+-exchanger 3b (Nhe3b) and (2) H+-ATPase-powered electrogenic uptake in H+-ATPase-rich (HR) cells and by (3) Na+-Cl----cotransporter (Ncc) expressed in NCC cells. The present study aimed t...

Convective water flow across respiratory epithelia in water-breathing organisms maintains transcutaneous oxygen (O 2 ) partial pressure (PO 2 ) gradients that drive O 2 uptake. Following hatch, larval fishes lack a developed gill and the skin is the dominant site of gas transfer, yet few studies have addressed the contribution of convective water f...

Freshwater (FW) fishes inhabit dilute environments and must actively absorb ions in order to counteract diffusive salt loss. Neuroendocrine control of ion uptake in FW fishes is an important feature of ion homeostasis and several important neuroendocrine factors have been identified. The role of serotonin (5-HT), however, has received less attentio...

In water-breathing fishes, the hypoxic ventilatory response (HVR) represents an increase in water flow over the gills during exposure to lowered ambient O2 levels. The HVR is a critical defense mechanism that serves to delay the negative consequences of hypoxia on aerobic respiration. However, the physiological significance of the HVR in larval fis...

Loss-of-function technologies, such as morpholino- and RNAi-mediated gene knockdown, and TALEN- and CRISPR/Cas9-mediated gene knockout, are widely used to investigate gene function and its physiological significance. Here, we provide a general overview of the various knockdown and knockout technologies commonly used in comparative physiology and di...

Purely diffusive O2 transport typically is insufficient to sustain aerobic metabolism in most multicellular organisms. In animals that are small enough, however, a high surface-to-volume ratio may allow passive diffusion alone to supply sufficient O2 transfer. The purpose of this study was to explore the impacts of internal convection on respirator...

Hypoxia-inducible factor (Hif) 1α, an extensively studied transcription factor, is involved in the regulation of many biological processes in hypoxia including the hypoxic ventilatory response. In zebrafish, there are two paralogs of Hif-1α (Hif-1A and Hif-1B), but little is known about the specific roles or potential sub-functionalization of the p...

Na+ uptake in larval zebrafish (Danio rerio) is coordinated by three mechanisms: Na+/H+-exchanger 3b (NHE3b) expressed in H+-ATPase-rich (HR) cells, an unidentified Na+ channel coupled to electrogenic H+-ATPase expressed in HR cells, and Na+-Cl--cotransporter (NCC) expressed in NCC cells. Recently, acid-sensing ion channels (ASICs) were proposed to...

Air breathing in fish is commonly believed to have arisen as an adaptation to aquatic hypoxia. The effectiveness of air breathing for tissue O2 supply depends on the ability to avoid O2 loss as oxygenated blood from the air-breathing organ passes through the gills. Here, we evaluated whether the armoured catfish (Hypostomus aff. pyreneusi)-a facult...

The effects of acute exposure to acidic water on Na(+) and Cl(-) homeostasis, and the mechanisms underlying their compensatory regulation, were investigated in the larval zebrafish Danio rerio. Exposure to acidic water (pH 4.0; control pH 7.6) for 2 h significantly reduced Na(+) uptake and whole body Na(+) content. Nevertheless, the capacity for Na...

The present study investigated the potential role of hypoxia-inducible factor (HIF) on calcium homeostasis in developing zebrafish (Danio rerio). It was demonstrated that zebrafish raised in hypoxic water (30 mmHg; control=155 mmHg) until 4 days post fertilisation exhibited a substantial reduction in whole body Ca(2+) levels and Ca(2+) uptake. Ca(2...

Carbon monoxide (CO) is a gaseous signalling molecule and is produced in vivo from the intracellular breakdown of heme via the heme oxygenase (HO) family of enzymes. In this study we investigated the role of the HO-1/CO system in the control of ventilation in zebrafish, Danio rerio. Immunohistochemistry revealed the presence of HO-1 in the chemorec...

Carbon monoxide (CO) is a gaseous neurotransmitter produced from the breakdown of heme via heme oxygenase-1 (HO-1; hypoxia inducible isoform) and 2 (HO-2; constitutively expressed isoform). In mammals, CO is involved in modulating cardiac function. The role of the HO-1/CO system in the control of heart function in fish, however, is unknown and inve...

Three gases comprising nitric oxide, carbon monoxide and hydrogen sulphide, collectively are termed gasotransmitters. The gasotransmitters control several physiological functions in fish by acting as intracellular signaling molecules. Hydrogen sulphide, first implicated in vasomotor control in fish, plays a critical role in oxygen chemoreception ow...

The present study tested the hypothesis that zebrafish (Danio rerio) aquaporin-1a1 (AQP1a1) serves as a multi-functional channel for the transfer of the small gaseous molecules, CO2 and ammonia, as well as water, across biological membranes. Zebrafish embryos were microinjected with a translation-blocking morpholino oligonucleotide targeted to AQP1...

Nitric oxide (NO) is a gaseous neurotransmitter, which, in adult mammals, modulates the acute hypoxic ventilatory response; its role in the control of breathing in fish during development is unknown.We addressed the interactive effects of developmental age and NO in the control of piscine breathing by measuring the ventilatory response of zebrafish...

Nitric oxide (NO) is a gaseous neurotransmitter, which in adult mammals, modulates the acute hypoxic ventilatory response; its role in the control of breathing in fish during development is unknown. We addressed the interactive effects of developmental age and NO in the control of piscine breathing by measuring the ventilatory response of zebrafish...

This book on ancient fishes unites the work of many specialists coming from different areas of biology.Hagfishes, lungfishes,Chondrosteans and Holosteans constitute the main subject of study.Phylogenetic relationships have mostly been revisited in the light of new molecular and developmental data.The morphology of several organs has also been revis...

Chemoreception in fish is critical for sensing changes in the chemical composition of the external and internal environments and is often the first step in a cascade of events leading to cardiorespiratory and metabolic adjustments. Of paramount importance is the ability to sense changes in the levels of the three respiratory gases, oxygen (O2), car...

Hydrogen sulfide (H2S) can act as a signalling molecule for various ion channels and/or transporters, however, little is known about its potential involvement in Ca(2+) balance. Using developing zebrafish (Danio rerio) as an in vivo model system, the present study demonstrated that acute exposure to H2S donors increased Ca(2+) influx at 4 days post...

Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxy...

In vertebrates, parathyroid hormone (PTH) is important for skeletogenesis and Ca(2+) homeostasis. However, little is known about the molecular mechanisms by which PTH regulates skeleton formation and Ca(2+) balance during early development. Using larval zebrafish as an in vivo model system, we determined that PTH1 regulates the differentiation of e...

Branchial ionocytes (ICs) are the functional units for ionic regulation in fish. In adults, they are found on the filamental and lamellar epithelia of the gill where they transport ions such as Na+, Cl- and Ca2+ via a variety of ion channels, pumps and exchangers. The teleost gill is extrinsically innervated by the facial (VI), glossopharyngeal (IX...

Although adult fish excrete their nitrogenous waste primarily as ammonia, larval fish may excrete a higher proportion as urea, an evolutionary strategy that lessens nitrogenous waste toxicity during early development. Previous studies firmly established that ammonia excretion is inhibited in adult fish acutely exposed to alkaline water. This study...

The presence of an interlamellar cell mass (ILCM) on the gills of goldfish acclimated to 7(o) C leads to the preferential distribution of branchial ionocytes to the distal edges of the ILCM where they are likely to remain in contact with the water and hence remain functional. Upon exposure to hypoxia, the ILCM retracts and the ionocytes become loca...

The ontogeny of carbon dioxide (CO2) sensing in zebrafish (Danio rerio) has not been examined. In this study, CO2-mediated increases in heart rate were used to gauge the capacity of zebrafish larvae to sense CO2. CO2 is thought to be detected via neuroepithelial cells (NECs), which are homologous to mammalian carotid body glomus cells. Larvae at 5...

Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxy...

The present study investigated the role of hydrogen sulfide (H2S) in regulating Na(+) uptake in larval zebrafish, Danio rerio. Waterborne treatment of larvae at 4 days post-fertilization (dpf) with Na2S or GYY-4137 (chemicals known to generate H2S) significantly reduced Na(+) uptake. Exposure of larvae to water enriched with NaCl (1 mM NaCl) caused...

The present study investigated the role of the transcription factor, glial cell missing 2 (gcm2), in Ca2+ regulation in zebrafish larvae. Translational gene knockdown of gcm2 decreased Ca2+ uptake and the density of ionocytes expressing the epithelial Ca2+ channel (ecac), and disrupted the overall Ca2+ balance. Ca2+ uptake and the expression of gcm...

Neuroepithelial cells (NECs) of the fish gill are respiratory chemoreceptors that detect changes in O2 and CO2/H(+) and are homologous to type I cells of the mammalian carotid body. In zebrafish (Danio rerio), stimulation of NECs by hypoxia or hypercapnia initiates inhibition of K(+) channels and subsequent membrane depolarisation. The goal of the...

In this study we investigated the role of heme oxygenase-1 (HO-1) in modulating the hypoxic and hyperoxic ventilatory responses of goldfish (Carassius auratus) acclimated to 7 and 25°C. HO-1 was present in the neuroepithelial cells (NECs; putative branchial O2 chemoreceptors) of fish acclimated to 7°C only. Hypoxia exposure increased gill HO-1 acti...

When faced with stress, animals use physiological and cellular strategies to preserve homeostasis. We were interested in how these high-level stress responses are integrated at the level of the whole animal. Here, we investigated the capacity of the physiological stress response, and specifically the β-adrenergic response, to affect the induction o...

Key points Hydrogen sulphide (H 2 S), a gaseous neurotransmitter, is involved in oxygen sensing in glomus cells, which are oxygen‐sensing cells found in the mammalian carotid body. Neuroepithelial cells (NECs) are oxygen‐sensing cells of fish and are thought to be phylogenetic precursors of mammalian glomus cells; however, the oxygen‐sensing mechan...

Professor Chris Wood stands alone as the world's preeminent researcher and authority in the broad field of comparative physiology and biochemistry. His scientific achievements are awe-inspiring – Chris has published over 600 papers (and counting) and has been cited a staggering 20,000 times! For

Ionic regulation and acid-base balance are fundamental to the physiology of vertebrates including fish. Acidification of freshwater ecosystems is recognized as a global environmental problem, and the physiological responses to acid exposure in a few fish species are well characterized. However, the underlying mechanisms promoting ionic and acid-bas...

The energetic costs of action potential (AP) production constrain the evolution of neural codes and brain networks. Cellular-level estimates of AP-related costs are typically based on voltage-dependent Na(+) currents that drive active transport by the Na(+)/K(+) ATPase to maintain the Na(+) and K(+) ion concentration gradients necessary for AP prod...

The involvement of the calcium-sensing receptor (CaSR) in Ca(2+) homeostasis was investigated in larval zebrafish, Danio rerio. The expression of CaSR mRNA was first observed at 3 h post-fertilization (hpf) and increased with development until plateauing at about 48 hpf. At 4 days post-fertilization (dpf), CaSR mRNA was increased in fish acclimated...

The contribution of the renin-angiotensin system (RAS) to Na+ uptake was investigated in larval zebrafish (Danio rerio). At 4 days post fertilization (dpf), the whole body angiotensin-II (ANG-II) level was significantly increased after 1- or 3-h exposure to acidic (pH = 4.0) or ion-poor water (20-fold dilution of Ottawa tapwater), suggesting rapid...

In the current study, the role of cAMP in stimulating Na(+) uptake in larval zebrafish was investigated. Treating larvae at 4 days post fertilization (dpf) with 10 µM forskolin or 1 µM 8-bromo cAMP significantly increased Na(+) uptake by 3- and 2-fold, respectively. The cAMP-dependent stimulation of Na(+) uptake was probably unrelated to protein tr...

Teleost fish living in freshwater are challenged by passive water influx; however the molecular mechanisms regulating water influx in fish are not well understood. The potential involvement of aquaporins (AQP) and epithelial tight junction proteins in the regulation of transcellular and paracellular water movement was investigated in larval zebrafi...

The effects of cortisol on epithelial permeability and sodium (Na+) handling during acid exposure were investigated in larval zebrafish (Danio rerio). The results demonstrated that the whole-body absorption of the paracellular permeability marker polyethylene glycol-4000 (PEG-4000) decreased with increasing levels of exogenous cortisol. Western blo...

Rainbow trout (Oncorhynchus mykiss) exposed to an acute heat shock (1h at 25°C after raising water temperature from 13°C to 25°C over 4h) mount a significant catecholamine response. The present study investigated the proximate mechanisms underlying catecholamine mobilization. Trout exposed to heat shock in vivo exhibited a significant reduction in...

The functional role of the tight junction protein claudin-b in larval zebrafish (Danio rerio) was investigated. We showed that claudin-b protein is expressed at epithelial cell-cell contacts on the skin. Translational gene knockdown of claudin-b protein expression caused developmental defects, including edema in the pericardial cavity and yolk sac....

Adult zebrafish, Danio rerio, exhibit hyperventilatory responses to absolute environmental CO2 levels as low as 1.0 mmHg. The ability of zebrafish to detect and respond to low ambient CO2 appears to be mediated by chemosensory neuroepithelial cells (NECs) of the gill filaments. Recent electrophysiological characterization of this response revealed...

The potential role of adrenergic systems in regulating Na(+) uptake in zebrafish (Danio rerio) larvae was investigated. Treatment with isoproterenol (a generic β-adrenergic receptor agonist) stimulated Na(+) uptake, whereas treatment with phenylephrine (an α(1)-adrenergic receptor agonist) or clonidine (an α(2)-adrenergic receptor agonist) signific...

Unlike other freshwater fish previously examined, zebrafish are capable of increasing their rate of Na(+) uptake during chronic exposure to acidic water (pH 4). In the present study, the potential role of cortisol in the induction of Na(+) uptake during acid-exposure was investigated. When zebrafish larvae (4days post-fertilization) were treated wi...

Freshwater teleosts are challenged by diffusive ion loss across permeable epithelia including gills and skin. Although the mechanisms regulating ion loss are poorly understood, a significant component is thought to involve paracellular efflux through pathways formed via tight junction proteins. The mammalian orthologue (claudin-4) of zebrafish (Dan...

Fish possess chemoreceptors able to sense increasing levels of ambient CO(2) and initiate various cardiorespiratory reflexes including hyperventilation and bradycardia. These chemoreceptors are localized predominantly to the gills, are oriented to sense the external environment and typically are stimulated by changes in environmental molecular CO(2...

Mechanisms of ion uptake by freshwater (FW) fish have received considerable attention over the past 80 years. Through an assortment of techniques incorporating whole animal physiology, electrophysiology and molecular biological approaches, three models have been proposed to account for Na(+) uptake. (1) Direct exchange of Na(+) and H(+) via one or...

Gill remodeling in goldfish (Carassius auratus) is accomplished by the appearance or retraction of a mass of cells (termed the interlamellar cell mass or ILCM) between adjacent lamellae. Given the presumed effects of gill remodeling on diffusing capacity, the goals of the current study were (1) to determine the consequences of increased aerobic O(2...

The concept that non-respiratory gases, such as nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H(2)S) functioned as signaling moieties is a relatively recent development, due in part to their ephemeral existence in biological tissues. However, from an evolutionary perspective these gases dominated the prebiotic and anoxic Earth and w...

The goal of this study was to determine the effect of the changes in gill morphology induced by dietary salt feeding on several aspects of gill function in rainbow trout Oncorhynchus mykiss maintained in fresh water with specific emphasis on Cl(-) uptake (J(IN)Cl(-)) and acid-base regulation. The addition of 11% NaCl to the diet caused J(IN)Cl(-) t...

In seawater-acclimated rainbow trout (Oncorhynchus mykiss), base secretion into the intestine is a key component of the intestinal water absorption that offsets osmotic water loss to the marine environment. Acid-base balance is maintained by the matched excretion of acid equivalents via other routes, presumably the gill and/or kidney. The goal of t...

If severe enough, periods of acute stress in animals may be associated with the release of catecholamine hormones (noradrenaline and adrenaline) into the circulation; a response termed the acute humoral adrenergic stress response. The release of catecholamines from the sites of storage, the chromaffin cells, is under neuroendocrine control, the com...

Twelve replicate populations of Drosophila melanogaster, all derived from a common ancestor, were independently evolved for 34+ generations in one of three treatment environments of varying PO(2): hypoxia (5.0-10.1 kPa), normoxia (21.3 kPa), and hyperoxia (40.5 kPa). Several traits related to whole animal performance and metabolism were assayed at...

Goldfish, Carassius auratus, adaptively remodel their gills in response to changes in ambient oxygen and temperature, altering the functional lamellar surface area to balance the opposing requirements for respiration and osmoregulation. In this study, the effects of thermal- and hypoxia-mediated gill remodeling on branchial Na(+) fluxes and the dis...

The involvement of a Na(+)/H(+) exchanger (NHE) in mediating Na(+) uptake by freshwater fish is currently debated. Although supported indirectly by empirical molecular and pharmacological data, theoretically its operation should be constrained thermodynamically, owing to unfavorable chemical gradients. Recently, there has been an increasing focus o...

Previous studies have demonstrated that chronic dietary salt loading causes hypertension and a decreased sensitivity of the systemic vasculature to α-adrenergic stimulation and other hypertensive stimuli (e.g. hypercapnia) in rainbow trout (Oncorhynchus mykiss). This reduced sensitivity to hypertensive stimuli is consistent with a possible blunting...

The rate-limiting enzyme in the biosynthetic pathway of catecholamines is tyrosine hydroxylase (TH), the activity of which is dependent on molecular oxygen. Zebrafish (Danio rerio) possess two non-allelic TH coding genes, TH1 and TH2. A principal goal of the present study was to determine if the expression of these genes is sensitive to environment...

β-Adrenergic receptors (βARs) are crucial for maintaining the rate and force of cardiac muscle contraction in vertebrates. Zebrafish (Danio rerio) have one β1AR gene and two β2AR genes (β2aAR and β2bAR). We examined the roles of these receptors in larval zebrafish in vivo by assessing the impact of translational gene knockdown on cardiac function....

Carbohydrate and protein metabolism were examined in rainbow trout, Oncorhynchus mykiss, fitted with mini-osmotic pumps which maintained plasma cortisol levels at approximately 100 or 200 ng∙mL−1 for 10 d. Plasma glucose, lactate, and protein levels were unaffected by 10 d of cortisol administration, despite a significant elevation in plasma cortis...

Experiments were conducted using a saline-perfused trout (Salmo gairdneri) head preparation in an attempt to determine the origin of HCO3− involved in gill apical Cl−/HCO3− exchange, the possibilities being plasma CO2 or HCO3−. Initial results showed that branchial Cl− influx was stimulated both by increased perfusate [HCO3−] and Pco2. Subsequent e...

The effects of acute exposure to chloramine T, a common aquaculture therapeutic agent, and its degradation products sodium hypochlorite and paratoluenesulphonamide (pTSA) on the respiratory and acid-base physiology of rainbow trout (Oncorhynchus mykiss) were examined using an extracorporeal circulation. Fish in which the coeliac artery was fitted w...

Acclimation of crucian carp and goldfish to temperatures below 15°C causes covering of the gill lamellae by a mass of cells termed the interlamellar cell mass (ILCM). Here we explore the cues underlying gill remodeling (removal or growth of an ILCM) and specifically test the hypotheses that 1) depletion of internal O(2) stores in the absence of any...

We have investigated the role of the gill chloride cell in transbranchial Na+ and Cl− uptake in four species of freshwater teleost maintained in water of identical ionic composition. The basic experimental protocol was to determine whether interspecific variability in the rates of whole body Na+ or Cl− uptake could be accounted for by similar inter...

A kinetic analysis (Michaelis constant (Km) and maximal flux (Jmax)) of the branchial Na+ and Cl− influx mechanisms, along with measurements of blood total CO2 content , net acidic–basic equivalent fluxes, and gill chloride cell morphology, was performed using rainbow trout (Oncorhynchus mykiss) before, during, and after 96 h exposure to environmen...

The effects of branchial chloride cell proliferation on ion transport capability and gill morphometry were evaluated in the rainbow trout, Oncorhynchus mykiss, to test the hypothesis that chloride cell (CC) proliferation benefits ionic regulation at the expense of efficient gas transfer. The extent of hormone-induced CC proliferation (using ovine g...

In situ hybridization was performed on sections of rainbow trout (Oncorhynchus mykiss) gill tissue using oligonucleotide probes complementary to the mRNA of the 31-kilodalton subunit of the bovine renal V-type H+-ATPase or rat kidney Band 3 anion exchanger ( exchanger). This was conducted in conjunction with measurements of whole-body net acid flux...

Effect of pseudobranch denervation on the ability of Salmo gairdneri to regulate blood ionic and acid–base balance was investigated in freshwater and following transfer to seawater. Denervation of the pseudobranch did not affect internal ionic or acid–base equilibrium in freshwater. Plasma [Cl−], [Na+], pH, total , and partial pressure of of trout...

The effects of saline gas composition and pH on various haemodynamic properties of the perfused trout head preparation were evaluated. Increasing the concentration of saline CO2 from a "normal" level of 0.3 (; 1 Torr = 133.322 Pa) to 5.0% resulted in a significant elevation of input pressure (Pi) and a reduction in the ratio of dorsal aortic to ant...