Some characteristics of mitochondrial monoamine oxidase activity in eggs of carp (Cyprinus carpio) and rainbow trout (Salmo gairdneri)

1. Monoamine oxidase (MAO) activity towards tryptamine, 5-hydroxytryptamine (5-HT) and phenylethylamine (PEA) has been measured in mitochondria isolated from carp and trout eggs. 2. In carp eggs all the tested substrates are metabolized and the highest affinity is found with tryptamine. In trout eggs a consistent level of MAO activity is obtained using tryptamine. 3. The inhibition dose-response curves of clorgyline and deprenyl indicate that both in carp and trout eggs there is only one form of mitochondrial MAO, distinct from MAO A and B which have been described in vertebrate tissues. 4. Both in carp and trout egg mitochondria a semicarbazide-sensitive amine oxidase is not involved in the deamination of the used substrates. 5. MAO found in carp and trout eggs might be involved in metabolism of some neurotransmitter monoamines during early developmental stages.     

Organ distribution of aldehyde dehydrogenase activity in the rainbow trout (Salmo gairdneri Richardson)

1. Aldehyde dehydrogenase activity was measured in gills, muscle, brain, intestine, kidney, heart and liver of rainbow trout, using 3,4-dihydroxyphenylacetaldehyde (the biogenic aldehyde derived from dopamine) as the substrate. 2. Aldehyde dehydrogenase activity was found to be present in all of the organs studied. 3. The highest activity was found in the liver (276 nmol/min.g wet wt of tissue). 4. A remarkably high activity was found in the heart (117 nmol/min.g). 5. The gills showed the lowest activity (1.9 nmol/min.g).     

Spermiogenesis in the rainbow trout (Salmo gairdneri)

In an ultrastructural study on the spermiogenesis of the rainbow trout (Salmo gairdneri R.) four spermatogenetic stages were identified. In young round spermatids, the nuclear chromatin was first heterogeneous (euchromatin and heterochromatin). Subsequently, it became more homogeneous and started to condense in the form of coarse granules and fibers and then into fibrils associated in ribbon-like elements which eventually partly fused together. During early spermiogenesis, a juxtanuclear vacuole appeared in the area where the nuclear envelope was specialized due to condensation of material between the two envelopes and a slight accumulation of nuclear material. This area was finally located in the anterior part of spermatids and spermatozoa; it probably plays a role during fertilization. A flagellar rootlet appeared early in spermiogenesis; it may play a role in the attachment of the flagellum to the nucleus since it persisted until the centriolar complex was definitively fixed in the implantation fossa. The flagellum did not display a plasma membrane and was first located in the cytoplasm, but when it was later extruded from the cell, it acquired a membrane. The cytoplasm was rich in ribosomes (free or in small groups) but poor in membranous organelles. The few mitochondria polarized around the centriolar complex were finally organized into an annular mid-piece. The spermatids remained connected by intercellular bridges until the end of spermiogenesis. The complexity of trout spermiogenesis is intermediate between that in poecilids and that in carp and pike, which have very simple spermatozoa. The role of the material from the nucleus and the cytoplasm reaching the Sertoli cell in the control of spermatogenesis has been discussed.     

The glutathione S-transferase activity in the kidney of rainbow trout (Salmo gairdneri)

Trout kidney contains 2.3 mmol GSH/kg. The cytosolic glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene as substrate is 0.35 mumol/min/mg protein. There is no detectable activity with 1,2-epoxy-3-(p-nitrophenoxy)propane, ethacrynic acid, p-nitrobenzyl chloride or p-nitrophenyl acetate. A variable proportion of the activity does not bind to a glutathione-affinity matrix. Its Km values for GSH and 1-chloro-2,4-dinitrobenzene are 3.0 and 5.1 mM, respectively. The rest of the activity is eluted from the affinity matrix as one main and two minor peaks. The main peak has Km values for GSH and 1-chloro-2,4-dinitrobenzene of 0.4 and 4.5 mM, respectively. Its subunit Mr is 22,900. The activity in the main peak is inhibited progressively by 1-chloro-2,4-dinitrobenzene with a rate constant of 0.11/min.     

Apomorphine-induced vomiting in rainbow trout (Salmo gairdneri)

1. The LD50 for a 7-day period following intraperitoneal injection of apomorphine-HCl was calculated to be 158 mg/kg in rainbow trout. 2. Intraperitoneal injection of apomorphine at doses of 60 mg/kg or greater caused vomiting of plastic balls which had been placed in the stomachs of rainbow trout. 3. Apomorphine-induced effects included vomiting, vomiting behavior, toxicity, increased respiration, impaired motor control and equilibrium, and increased aggression. 4. The vomiting control mechanism of trout may be similar to that described in mammals.     

Chromosome polymorphism in the rainbow trout (Salmo gairdneri Richardson)

Chromosome preparations from lymphocyte cultures of 50 rainbow trout were studied. Diploid chromosome numbers of 59, 60, 61, 62 and 63 were found in different individuals in which the arm number (NF) was 104. Intraindividual polymorphism was found at a low level in 25 of the fish. The results suggest that numerous chromosome polymorphisms exist in rainbow trout.     

Crystallization of the rainbow trout (Salmo gairdneri) haemoglobin IV

Crystals of rainbow trout (Salmo gairdneri) haemoglobin IV were grown in mini batches from a solution of ammonium sulphate. Large single crystals grew over five days and were up to 2 mm in length. X-ray diffraction experiments indicated a space group of C222(1) with unit cell dimensions of a = 85.3 A, b = 94.6 A and c = 105.7 A. The crystals diffract to better than 2.5 A but exhibit some mosaicity along the c axis.     

The glutathione S-transferase activity in the pyloric caeca of rainbow trout, Salmo gairdneri

Pyloric caeca of trout contain 1.9 mmol GSH/kg tissue. Cytosolic glutathione S-transferase activity with 1-chloro-2,4-dinitrobenzene as substrate is 0.06 mmol/min/g protein. Cholate (3.3 mM) inhibits cytosolic transferase activity by 55% at pH 6.6 and by 4% at pH 7.4. The transferases do not bind 8-anilino-1-naphthalene sulphonate at pH 7.4. The cytosolic transferases are inactivated progressively by 1-chloro-2,4-dinitrobenzene, 50% of their activity being lost in 5.0 min. A minority of the activity does not bind to a glutathione-affinity matrix. At pH 6.6 its apparent Michaelis constants for GSH and 1-chloro-2,4-dinitrobenzene are 0.88 and 9.1 mM respectively. The rest of the activity is eluted from the affinity matrix as a single peak. Its apparent Michaelis constants for GSH and 1-chloro-2,4-dinitrobenzene are 0.33 and 2.9 mM respectively. Its subunit Mr is 22.4 kDa.     

Social dominance and interrenal cell activity in rainbow trout,Salmo gairdneri (Pisces,Salmonidae)

Synopsis The relationship between standing in a dominance hierarchy and physiological stress was studied in rainbow trout. Individual fish were assigned relative dominance ranks, based on behavioral observations in a large, simulated stream tank. These ranks were compared to histometric measures of interrenal cell activity. Fish, isolated individually in the stream tank had significantly lower levels of interrenal activity than fish from the crowded holding tank. Groups of fish in the stream tank formed stable, linear dominance hierarchies. Interrenal activity correlated inversely with dominance rank, with the exception that top ranking fish had higher activity than expected. Possible cause and effect relationships are discussed.     

Relative growth of tissues at different somatic growth rates in rainbow trout Salmo gairdneri Richardson

Growth of tissues (heart, spleen, liver, gonad, gut, skin, visceral fat and carcase) in immature rainbow trout relative to growth of whole fish, was examined by means of allometric analysis (y=ax^b; Huxley, 1932) of wet and dry weights. Relative growth rates of tissues are compared in an initial sample of fingerlings (< 11·29 g), and in fish (> 11·29 g) growing rapidly (at 12°C ad libitum rations) and slowly (at 12°C, 4–5% rations, and 7°C ad libitum rations). In the fingerlings of the initial sample, the major tissues by weight (liver, gut, skin, visceral fat) increased relatively more rapidly than whole body weight (i.e. with positive allometry; b> 1·00), and carcase increased more slowly than body weight (b< 1·00). Above fingerling size, the reverse holds: tissues other than carcase (with exception of visceral fat) increased less rapidly than body weight (b < 1·00), and carcase more rapidly (b > 1·00). These principles hold for post-fingerling, immature rainbow trout, regardless of growth rate differences of whole fish, and even in fish that also received bGH (bovine growth hormone). The characteristic b (slope) values in the allometry equations for the wet and dry weights of the various tissues tend to remain constant, despite whole fish growth rate differences and the effects of this constancy are to maintain approximate constancy of body proportional (%) wet and dry weights. It is emphasized however that the effect of b values only slightly > or < 1·00 can cause important changes in the proportional (%) weights of major tissues as fish continue to increase in size. In low (4–5%) rations fish (without bGH) the slope (b) value for gut is less than for fish on ad libitum rations with the result that gut proportional weight is significantly less among these fish. In fish on ad libitum rations at 7°C, the slope (b) value for skin is greater than for all other (12°C) groups; skin proportional weight for the 7°C group is therefore, significantly greater. The overall impression of relative growth in immature rainbow trout is of remarkable conservativeness of body proportional weights regardless of overall somatic growth rate.     

Aldehyde dehydrogenase activity in brain and liver of the rainbow trout (Salmo gairdneri Richardson)

Aldehyde dehydrogenase (ALDH) activity was measured in brain and liver of rainbow trout by using 3,4-dihydroxyphenylacetaldehyde (DOPAL, the biogenic aldehyde derived from dopamine) as the substrate. The amount of the corresponding acid produced was quantified by high-performance liquid chromatography with electrochemical detection. Both in brain and liver, the ALDH activity showed a high affinity for the substrate with an apparent Km of 3.7 microM in brain and 2.4 microM in liver. The kinetic experiments with brain ALDH also indicated the presence of an isozyme with a low affinity for DOPAL with a Km around 150 microM. The Vmax of the liver ALDH activity varied between 179 and 536 nmol/min.g, i.e., about 25-75 times higher than that of the low-Km activity in brain. The ALDH activity showed a maximum around pH 8.5, it was stimulated by Mg2+, and disulfiram was found to be a potent inhibitor of the enzyme. The results suggested that the majority of the ALDH activity was located in mitochondria (60-70% with regard to the brain and 70-80% with regard to the liver), while the remaining activity appeared to be cytosolic in both organs. No microsomal ALDH activity could be found.     

Ventilation in rainbow trout (Salmo gairdneri, Richardson) with damaged gills

An account is given of damage to the gills of trout which involved reduction in total filament length and consequently reduced respiratory surface area. It was noted that fish with the greatest gill damage tended to ventilate the gills by active swimming (ram ventilation) to a greater extent than those with more normal gills.     

Synthesis of platelet activating factor by tissues from the rainbow trout, Salmo gairdneri

In mammals, platelet activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a lipid mediator with biological activity at concentrations in the subnanomolar range. Although PAF is known to have many activities in mammals, little is known about its synthesis and importance in other vertebrate groups. We demonstrate here the synthesis of PAF from [3H]acetate by slices of trout gill, kidney, liver and spleen. PAF synthesis was stimulated by the calcium ionophore A23187 and was time-dependent. The radiolabeled PAF produced was characterized by TLC, HPLC, derivatization and by saponification and phospholipase A2 hydrolysis. These findings suggest that PAF may be an important mediator in fish.