Rainbow Trout Salmo Gairdneri Research Articles

The Fine Structure of Gill Filaments in the Fingerlings of Rainbow Trout Salmo gairdneri

The Fine Structure of Gill Filaments in the Fingerlings of Rainbow Trout Salmo gairdneri

WEBB SCALES FAST-START MANEUVERS

![Figure][1] Paolo Domenici discusses Paul Webb's paper entitled ‘The effect of size on the fast-start performance of rainbow trout Salmo gairdneri, and a consideration of piscivorous predator–prey interactions’. A copy of the paper can be obtained from <http://jeb.biologists.org/cgi/

In Vitro Elicitation of Intestinal Immune Responses in Teleost Fish: Evidence for a Type IV Hypersensitivity Reaction in Rainbow Trout

In fish the gut immune system has been the subject of few investigations until now. Here, we provide novel morphological and immunological data on the gut isolated from rainbow trout Salmo gairdneri. The pyloric (P) and terminal (T) segments of trout gut, when morphologically examined, evidenced lymphocytes and macrophages (MØ) loosely dispersed in the intestinal mucosa and in the lamina propria in the absence of typical Peyer's patches-like structures. Furthermore, incubation of P and T sections with Candida albicans (Ca) and functional analysis of supernatants generated some interesting results. In fact, active supernatants, when compared with controls, exhibited cytokine-like activities attributable to the presence of interferon (IFN)-γ and migration inhibiting factor (MIF), respectively. In particular, IFN-γ-like activity gave rise to an enhancement of Ca phagocytosis by MØ, whereas MIF inhibited MØ migration in agarose. Taken together, these in vitro data suggest that the gut-associated lymphoreticular tissue in fish possesses the appropriate armamentarium to mount a type IV hypersensitivity response when challenged by microbial antigens.

Lymphoreticular System in Fish: Erythrocyte-Mediated Immunomodulation of Macrophages Contributes to the Formation of Melanomacrophage Centers

In fish, melanomacrophage centers (MMC) represent the equivalent of germinal centers of birds and mammals. They consist of aggregates of macrophages filled with fragments of cells, mainly erythrocytes, and various pigments such as hemosiderin, lipofuscin, and melanin. The kidney, the spleen, and the liver contain many MMC either moving freely or encapsulated in the context of the lymphoreticular tissue. Here, we have demonstrated for the first time that MMC exist in the kidney, spleen, and liver of the rainbow trout Salmo gairdneri Richardson by using traditional stainings and cytoenzymatic methods: periodic acid-shiff, α-naphthyl acetate esterase, and peroxidase. Finally, in the view of the already described peripheral interaction between fish erythrocytes (FE) and macrophages (MØ), we postulate that these cellular aggregates (rosettes) travel to distant organs, thus contributing to the formation of MMC in the kidney, spleen, and liver.

Maturation of Fish Erythrocytes Coincides with Changes in their Morphology, Enhanced Ability to Interact with Candida albicans and Release of Cytokine‐Like Factors Active Upon Autologous Macrophages

Erythrocytes from the rainbow trout Salmo gairdneri Richardson (Salmo g.R.) were classified into immature and mature populations, respectively, by measuring longitudinal diameters. More elongated fish erythrocytes (FE), classified as mature cells, were those interacting with Candida albicans (CA) in a higher frequency in terms of either binding to the fungus or its intracellular engulfment. At the same time, in the rosetting phenomenon more elongated mature FE surrounded macrophages (MØ) phagocytosing CA. Finally, FE activated by CA released in the supernatants cytokine‐like factors able to modulate MØ functions. In particular, these active supernatants were analyzed for their capacity to inhibit MØ migration Macrophage Inhibition Factor (MIF) activity and enhance MØ phagocytosis. Both activities were detected in supernatants from CA stimulated FE but not in control supernatants. MIF activity could play a role in the accumulation of MØ in the context of functional rosettes, while the factor enhancing MØ phagocytosis could promote clearance of CA in a more efficacious way.

A Phylogenetic Comparison Between Acute Monocytic Leukemia Cells and Monocytes–Macrophages in Lower Vertebrates

In humans, monocytes and macrophages (MØ) play a central role in immune regulation, tissue maintenance and pathogen control. In lower vertebrates, a few studies have been conducted on MØ like cells. In acute monocytic leukemia monocytic cells, as immature cells restrained in one of the phases of their ontogenesis, would offer the opportunity to rebuild an archaic condition helpful to understand the phylogenesis. Therefore, aim of this work was to characterize in the Rainbow trout (Salmo Gairdneri Richardson) MØ and compare them with acute leukemia monocytic cells.In the trout, MØ's morphology is similar to that of mammals. In particular, MØ possess an irregular embryoshaped nucleus occupying 2/3 of the cell, while the peripheral cytoplasmic profile is irregular with extroflexed plasmalemma and pseudopods.A morphological transition towards MØ is featured by a wavy hyaline classical membrane and an irregular and extroflexed surface.Some aspects of erythrophagocytosis represented a finding of great interest indicating that the hemocatheretic function could take place directly in circulation. This condition, also observed in human acute monocytic leukemia, suggests that the information to the erythrophagocytosis is restrained under physiological conditions.Non-specific esterases, which are positive in human MØ smear and MØ from human lymph node tissue, were also positive in the teleost studied but with a dysomogeneous pattern. Consequently non-specific esterase system is phylogenetically conserved.A lack of immune-reactivity with the anti-CD68 monoclonal antibody (MoAb) on smear and trout tissue sections was observed. On the contrary, strong positivity was detected on human lymph node sections.In trout, the presence of MØ and circulating MØ like cells exhibiting an erythrocatheretic function in the circulation would indicate a primordial function that has later been replaced by the liver and the spleen.

Ferritin from the spleen of the Antarctic teleost Trematomus bernacchii is an M-type homopolymer.

Ferritin from the spleen of the Antarctic teleost Trematomus bernacchii is composed of a single subunit that contains both the ferroxidase center residues, typical of mammalian H chains, and the carboxylate residues forming the micelle nucleation site, typical of mammalian L chains. Comparison of the amino-acid sequence with those available from lower vertebrates indicates that T. bernacchii ferritin can be classified as an M-type homopolymer. Interestingly, the T. bernacchii ferritin chain shows 85.7% identity with a cold-inducible ferritin chain of the rainbow trout Salmo gairdneri. The structural and functional properties indicate that cold acclimation and functional adaptation to low temperatures are achieved without significant modification of the protein stability. In fact, the stability of T. bernacchii ferritin to denaturation induced by acid or temperature closely resembles that of mesophilic mammalian ferritins. Moreover iron is taken up efficiently and the activation energy of the reaction is 74.9 kJ.mol(-1), a value slightly lower than that measured for the human recombinant H ferritin (80.8 kJ.mol(-1)).

FISH IMMUNOLOGY. I. BINDING AND ENGULFMENT OF CANDIDA ALBICANS BY ERYTHROCYTES OF RAINBOW TROUT (SALMO GAIRDNERI RICHARDSON)

ABSTRACTThe role of fish erythrocytes (FE) as phagocytic cells has poorly been investigated, until now. Here, we have focussed our attention on the interplay between rainbow trout (Salmo gairdneri Richardson) erythrocytes and Candida albicans (CA). At the same time, the intervention of autologous head kidney macrophages (MØ) in the CA processing by FE has been studied. Data show that CA particles bind to FE, which, in turn, are able to engulf but not kill them. In the presence of MØ, a decrease of FE with bound CA occurs and, in some microscopic images, FE form rosettes with MØ. Phagocytosis of CA is higher in rosetting MØ than in non-rosetting ones. According to our findings, it appears that FE represent a reservoir of engulfed CA and rosetting is an efficacious phenomenon of presentation of pathogens to MØ, where an effective clearance of them can take place.

Sonoelectroanalytical Determination of Heavy Metals in Fish Gill Mucous

Fish gill mucous is used as a nondestructive biomarker for the detection of heavy metals by sono-square-wave anodic stripping voltammetry (sono-SWASV). The mucous sample was obtained by gently rinsing the rainbow trout (Salmo gairdneri) with a solution of borate buffer at pH 7. A glassy carbon electrode plated in situ with mercury was used in a face on arrangement with the ultrasonic horn to first demonstrate that voltammetric measurements can accurately be made in borate buffer. The optimum deposition potential and ultrasound power for copper from a dilute mucous solution was then determined and used to give a quantitative assessment of copper content using the microaddition technique. The results had a % RSD of less than 2 % and compared favorably with an independent blind analysis. The potential of the technique for detection of other heavy metals for example lead, was also demonstrated. We conclude that sono-SWASV of gill mucous may present a novel alternative to the destructive conventional techniques due to its accuracy, rapidity and facile methodology.

Modelling temperature-dependency in biology by generalizing temperature coefficient Q10

Temperature is an important biological factor and affects numerous biological processes and phenomena. Many models have been proposed to describe the effects of temperature on these biological processes. In this paper, I develop a general temperature and time-dependent model of the state of a biological process as a function of temperature and time. This model generalizes that underlying temperature coefficient and can be used to estimate its parameters from data on the state, temperature and time, or on any two of the three quantities, given the other fixed. To demonstrate its utility in data analysis, I use a special case to estimate some parameters from data on the duration of one mitotic cycle during synchronous cleavage divisions of the rainbow trout Salmo gairdneri and the Russian sturgeon Acipenser güldenstädti as a function of water temperature.

Effect of Dietary Fatty Acids on Ca2+-ATPase Activity of the Sarcoplasmic Reticulum of Rainbow Trout Skeletal Muscle

Effects of different dietary lipids, corn oil, cod liver oil, and beef tallow, on lipid compositions and Ca2+-ATPase activity of the rainbow trout Salmo gairdneri sarcoplasmic reticulum (SR) were examined. The levels of phosphatidylethanolamine (PE) of the muscle and the SR were lower in fish fed for 2 months on diets rich in n-6 fatty acids or deficient in polyunsaturated fatty acids (PUFA) than in those fed n-3 fatty acid rich diet. Fatty acid compositions of muscle well reflected those of the diets. On the other hand, the SRs contained higher levels of polyunsaturated fatty acids, such as 22:6n-3, than muscle. In particular, PE fractions of each SR exhibited very high contents of polyunsaturated fatty acids and feeding PUFA-deficient diet for 3 months failed to reduce markedly the level of 22:6n-3 in PEs. Fatty acid compositions of phosphatidylcholine (PC) fractions of the SRs were altered by dietary fatty acids more easily than those of PEs. n-3 Fatty acid rich diet feeding caused reduction of SR Ca2+-ATPase activities. There was hardly any difference in peptide mapping patterns of Ca2+-ATPase proteins through the experimental stages, suggesting that there was practically no change of the Ca2+-ATPase moiety itself in the primary structure. These results suggested that dietary fatty acid compositions would alter lipid class and fatty acid compositions of the rainbow trout SRs and consequently lipid conformation changes. It was concluded that such physiological changes in lipids might affect the SR Ca2+-ATPase activities.

ACTIVITY OF ESTERASES FROM DIFFERENT TISSUES OF FRESHWATER FISH AND RESPONSES OF THEIR ISOENZYMES TO INHIBITORS

Activity of nonspecific esterase from different tissues (i.e., liver, gallbladder, heart, intestine, and muscle) of five species of freshwater fish, namely, topmouth gudgeon (Pseudorasbora parva), goldfish (Carassius auratus), nile tilapia (Tilapia nilotica), mosquitofish (Gambusia affinis), and rainbow trout (Salmo gairdneri) was tested using α-naphthyl acetate as sub strate. The results indicated that activity of the enzyme was mainly concentrated in the digestive system (i.e., intestine, liver, bile). The overall activity was highest in nile tilapia, followed by mosquitofish, topmouth gudgeon, goldfish, and lowest in rainbow trout. Electrophoresis and the following in vitro treatment of the isoenzymes with triphenol phos phate (TPP, an inhibitor of carboxylesterase) indicated the TPP-sensitive esterase was mainly distributed in liver of the five species. The enzyme was not found in the other five tissues (including gill) except in gallbladder of topmouth gudgeon and goldfish. The corre lation was obviously improved between susceptibility and detoxification capacity if activity of the TPP-sensitive esterase was employed instead of that of the nonspecific esterase to make the comparison. In vitro treatment of nonspecific esterase in liver with malaoxon proved that the active metabolite of malathion inhibited a different isoenzyme from the TPP-sensitive one.

Correlation between biochemical parameters and susceptibility of freshwater fish to malathion.

Acute toxicity (96-h LC50) of malathion was tested using five species of freshwater fish, namely, topmouth gudgeon (Pseudorasbora parva), goldfish (Carassius auratus), nile tilapia (Tilapia nilotica), mosquitofish (Gambusia affinis), and rainbow trout (Salmo gairdneri). Correlation was found between susceptibility and biochemical parameters such as activity of brain acetylcholinesterase (AChE) and in vitro resistance of the enzyme to inhibition (IC50) of malaoxon (a major metabolite of malathion). The in vitro study also showed that malaoxon instead of malathion was the main inhibitor of AChE. Susceptibility to malathion was considerably changed as the fish was pretreated with piperonyl butoxide (PB, a P-450 inhibitor) and triphenyl phosphate (TPP, an inhibitor of carboxylesterase), respectively. Toxicity of malathion was significantly increased by TPP, but the responses of fish to PB were quite different among species. This suggested that both carboxylesterase and monooxygenase played an important role in susceptibility determination, and great variations existed among species in activity of monooxygenase.

G i protein mediates adenylate cyclase inhibition by neurohypophyseal hormones in fish gill

Adenylate cyclase activity was measured on membrane fractions from the gill epithelium of rainbow trout Salmo gairdneri. Basal and glucagon-stimulated activities responded negatively to homologous neurohypophyseal peptides (arginine-vasotocin and isotocin). This inhibitory effect was totally abolished in the presence of pertussis toxin (IAP). The guanine nucleotide dependence of the enzyme was further explored by using GTP, GDP, and their stable analogs Gpp(NH)p, GTPγS, and GDPβS. The results suggest that neurohypophyseal peptides at low concentrations inhibit the adenylate cyclase system directly by way of a G i-protein, thus implying the intervention of a new type of membrane receptor for these hormones in fish gills.

Public Evaluation of Fish Tainting from Pulp and Paper Mill Discharges

As part of the Remedial Action Plan (RAP) programs for the St. Lawrence and Spanish Rivers in Ontario, Canada, tainting evaluations were conducted using members of the Public Advisory Committees (PACs) and the RAP teams. Triangle test sensory evaluations were conducted on caged rainbow trout (Salmo gairdneri) exposed insitu upstream and downstream of the pulp and paper mill diffuser outfalls In the St. Lawrence River only, evaluations were conducted on indigenous yellow perch (Perca flavescens) caught upstream and downstream of the mill discharge . In both locations, the odour of the flesh from the caged trout exposed above the diffuser outfall was not judged significantly different from caged trout exposed downstream of the discharge. However, the indigenous perch caught downstream of the mill in the St. Lawrence River were judged by the panelists to have a significantly more objectionable odour than those caught upstream of the discharge. While the effluent tainting potential appears to have been eliminated in the Spanish River, further studies are required to determine the source and magnitude of tainting concerns in the St. Lawrence River. The sensory test and results reported here provide useful tools for evaluating the tainting potential of pulp mill discharges and for assessing perceived consumer quality of the fish exposed to these effluents.

Syntheses of recombinant yellowtail and flounder growth hormones in Escherichia coli.

For syntheses of recombinant yellowtail and flounder growth hormones (r-yGH and r-fGH) in E. coli, expression plasmids were constructed. The expression level of r-yGH and r-fGH in the host cells were very high, reaching 15 and 8% of the total protein, respectively. These product proteins were accumulated in inclusion bodies in the cells. The recombinant hormones were isolated from the pellets ina glutathione reduction/oxidation buffer. The refolded hormones were further purified by DEAE-Toyopearl 650M chromatography to homogeneity. The purified r-yGH and r-fGH were composed of 188 and 174 amino acid residues, respectively, having amino-terminal sequences starting with methionine. The recombinant hormones had potent growth-promoting activities on juvenile rainbow trout Salmo gairdneri in a dose-dependent manner.

The Pattern of Trunk Lateral Line Afferents and Efferents in the Rainbow Trout &lt;i&gt;(Salmo gairdneri)&lt;/i&gt;

The primary projections of the mechanosensory posterior lateral line nerve of the rainbow trout Salmo gairdneri, a teleost without lateral line specializations, were studied by applying horseradish peroxidase (HRP). The afferents project nearly exclusively to the nucleus medialis and a small nucleus caudalis in the hindbrain, and to the eminentia granularis. In addition, there is a sparse projection to the cerebellum, but a projection to the magnocellular nucleus is lacking. The afferent projection to the lateral part of the eminentia granularis is more dense than the projection to the medial nucleus, as shown by image processing of the HRP labeling. The efferent fibers originate from a bilateral pair of large octavolateral nuclei in the hindbrain. Characteristic for these nuclei are their large, fusiform and bipolar neurons. Another specific feature is the oblique orientation of the somata, with the main dendritic shaft coursing ventrolaterally and the axonal shaft coursing dorsomedially. The axons of the efferent neurons bifurcate. The shape, orientation and size of the efferent somata are the same in the entire efferent nucleus. In contrast to other teleosts, the occurrence of efferent somata found contralaterally (21%) is substantial. The part of the octavolateral efferent nucleus innervating the neuromasts of the trunk is estimated to contain at most 150 cell bodies unilaterally.

Hydrothermically treated soy beans as source of dietary protein for rainbow trout(Salmo gairdneri, R.)

(1991). Hydrothermically treated soy beans as source of dietary protein for rainbow trout (Salmo gairdneri, R.). Archiv fur Tierernaehrung: Vol. 41, No. 2, pp. 223-228.

An Analysis of acid vase,ionic and water balance in rainbow trout (salmo gairdneri) exercised at cruising speeds

Rainbow trout (Salmo gairdneri) were exercised at cruising speeds for 5hours. A slight but significant increase in dorsal aortic blood pH after I hour ofexercise was accompanied by significant decreases in PeDl and total C02content of blood. These changes were maintained throughout the exercise periodof 5 hours. This respiratory alkalosis could be due to hyperventilation and/orthe result of increased uptake of Na+ and Cl- which occurred along with theincrease in plasma volume in order to maintain normal osmotic concentrations.The uptake of Na+ and CI- occurred presumably via branchial Na+ /H+ andCI- /HCO2- ion exchange mechanisms.

DNA adducts as early bioindicators of chemical exposure

Sensitive analytical methods indicate the presence of hundreds of chemical contaminants in our environment. However, concentration of these pollutants is usually at the low parts per million or parts per billion level. At such low levels, toxicants induce long-term (chronic) rather than short-term (acute) toxicities. Experiments are designed to evaluate chronic toxicity using early bioindicators. Recently, fish have been used as experimental animals because some species show early (weeks as opposed to years in other research animals), sensitive responses. Thus, medaka (Oryzias latipes), following exposure to diethylnitrosamine (DEN), exhibited liver tumors in several weeks; more interestingly its DNA was modified (to a 'DNA-adduct') after only 24-48 hours exposure. Such adducts show promise as early bioindicators because they are formed within hours of exposure. The formation of DNA-adducts were monitored in medaka and rainbow trout (Salmo gairdneri) exposed to DEN by aqueous or intra-peritoneal routes. Using HPLC-Fluorimetry, O (6)-ethylguanine (O (6)-EtGua) was detected and monitored in acid thermal hydrolysates of DNA isolates. (Detection limit for O (6)-EtGua was as low as 3 ng, 1.7×10(-11) moles). Fourier transform cyclotron resonance mass spectrometry with IR laser desorption/ionization was used advantageously to establish the structure of nucleotides, bases and nucleosides directly, without further cumbersome derivatizations. Other aspects of DNA-adducts are discussed.