Teleost Tilapia Mossambica Research Articles

Studies on some kinetic parameters of aldolases in selected tissues of the freshwater fish (Tilapia mossambica) under the toxic impact of methyl parathion.

Kinetic parameters of aldolases in muscle, gill, liver and brain tissues of the teleost Tilapia mossambica were studied at sublethal concentrations with methyl parathion (MP). The pH activity profiles were optimal at pH 7.0 and 9.0 in gill, liver and brain tissues, whereas only a single peak at pH 7.0 was observed in muscle tissue of both control and MP-exposed fish. The pH 7.0-specific peak was confirmed as aldolase A and the pH 9.0-specific peak represents the tissue-specific aldolases: aldolase B in liver, aldolase C in brain and aldolase B-C in gill. It is further confirmed with the inhibitor sensitivity of aldolases at two peaks with 6 x 10(-3) M ATP or AMP. The pH-based substrate-dependent kinetics of aldolases showed a variable trend. The tissue-specific activity of pH 7.0-specific aldolases showed low Km values for gill followed by muscle, liver and brain tissues, suggestive of its high enzyme-substrate affinity. During MP exposure, the Vmax values of pH 7.0-specific aldolases in muscle, gill and brain were unchanged compared to controls, but Km values were decreased. The pH 9.0-specific aldolases of gill and liver from MP-exposed fish showed decreased Km values with a slight increase in Vmax values. Effectors such as lysine, arginine and Ca2+ inhibited, while histidine, cysteine, aspartic acid and alpha-ketoglutaric acid elevated the activity levels of aldolases.(ABSTRACT TRUNCATED AT 250 WORDS)

Histopathological alterations in the liver of freshwater teleost Tilapia mossambica in response to cadmium toxicity

The effects of lethal (50 ppm) and sublethal (5 ppm) concentrations of CdCl 2 on the liver of the freshwater teleost Tilapia mossambica were studied by routine histological techniques. Engorged blood vessels, congestion, vacuolar degeneration of hepatocytes, necrosis of pancreatic cells, and fatty changes in the peripancreatic hepatocytes were the pathological alterations observed in liver.

Effect of cupric chloride on oxidative metabolism in the freshwater teleost, Tilapia mossambica

The freshwater teleost Tilapia mossambica was subjected to lethal ( 6.0 mg · liter −1 = LC 50 48 hr ) and sublethal (1.5 mg · liter −1 copper treatment for 1, 7, and 14 days. The whole animal oxygen consumption and the activity levels of succinate dehydrogenase and lactate dehydrogenase in liver and muscle were studied. The decrease in oxygen consumption and succinate dehydrogenase activity and significant increase in lactate dehydrogenase activity suggest that the stressed fish is meeting its energy requirements through anaerobic oxidation and these enzymes can be used as indicators in monitoring metal-induced toxicity in fish.

Correlation between subacute toxicity of malathion and acetylcholinesterase inhibition in the tissues of the teleostTilapia mossambica

Correlation between subacute toxicity of malathion and acetylcholinesterase inhibition in the tissues of the teleostTilapia mossambica

Sodium-retaining bioassay of prolactin in the intact teleost Tilapia mossambica acclimated to sea water

A bioassay method for fish prolactin was developed based on the ability of prolactin to increase the plasma sodium concentration of intact Tilapia mossambica acclimated to sea water. The plasma sodium concentration is linearly related to log dose of ovine prolactin. Homogenates of whole pituitary gland from fresh water T. mossambica give a parallel dose response. A significant elevation of plasma sodium is elicited by 4 μg/g body wt of ovine prolactin. The same amount (wet wt) of whole pituitary gland from freshwater T. mossambica has equal potency, indicating that the assay is much more sensitive to at least some teleost prolactins than to mammalian prolactins. The assay is unaffected by ACTH, dexamethasone, bovine growth hormone, porcine prolactin, or human chorionic somatomammo-from Cichlasoma labiatum, Roccus saxatilis, Mugil cephalus, and Poecilia latipinna, In addition to Tilapia, sodium-retaining activity was detected in pituitaries from Cichlasoma labiatum, Roccuss saxatilis, Mugil cephalus, and Poecilia latipinna, but not in any of 13 other species of fish examined. This activity was restricted to the rostral pars distalis of Tilapia and Cichlasoma. It was localized in a single prominent band with a R f of .47 after electrophoresis of Tilapia pituitaries. The sodium-retaining potency of seawater Tilapia pituitaries was about one-eighth that of freshwater Tilapia pituitaries.

Somatotropic and sodium-retaining effects of human growth hormone and placental lactogen in lower vertebrates.

Human growth hormone resembled ovine prolactin in its ability to promote growth of bullfrog (Rana catesbeiana) tadpoles. Both hormones stimulated a dose-related increase in tail length, tail height and body weight, but prolactin tended to be more potent. Human growth hormone was about half as active as prolactin in causing sodium retention in the teleost Tilapia mossambica. On the other hand, human placental lactogen failed to induce either growth responses in tadpoles or sodium retention in Tilapia. (Endocrinology93: 960, 1973)

Adaptations to osmotic stress in the fresh-water euryhaline teleost Tilapia mossambica. IV. Changes in blood glucose, liver glycogen and muscle glycogen levels

Some aspects of osmoregulation energetics have been studied in the euryhaline teleost Tilapia mossambica (Peters) acclimated to media of different salinities. In stress media (75 and 100% sea water) the blood glucose of the fish increases significantly, accompanied by a corresponding increase in oxygen consumption and cytochrome-oxidase activity, suggesting that oxidative degradation of blood glucose is the predominant energy source for osmotic work in these stress media. It is likely that the variations in the blood-glucose level as a function of acclimation to the heterosmotic media —except the natural fresh-water medium — are governed by the combined effects of salinity of the medium and blood-medium osmotic gradient, rather than by the effect of any one of them separately. Perhaps, metabolic homoeostasis is in operation in the natural fresh-water medium. Depletion of muscle glycogen at significant levels is noticed only in stress media. Presumably, there is an augmentation of oxidative metabolism with glycolysis to meet the exacting energy demands for heavy osmotic work in high-stress media. Prior acclimation to 75% sea water (24.375‰ S) facilitates subsequent acclimation to 100% sea water (32.50‰ S) with less energy cost —an instance of “facilitation acclimation”. Smaller individuals of T. mossambica osmoregulate with less energy expenditure than larger ones. Thus, smaller individuals are osmotically more efficient.

Origine des poussées ovocytaires chezTilapia mossambica

1. In the teleostTilapia mossambica (Peters), new crops of oocytes arise from nests of cells of the germinal epithelium as well as from the epithelial strands ramifying into the ovocoel. 2. There is no evidence to indicate that degenerating follicle cells form a source for a new crop of oocytes. 3. After one spawning is over, the follicular layer of the mature unspawned ova alone undergo atresia. 4. Neither immature oocytes nor oocytes in the growth stages undergo degeneration. 5. The occurrence of immature, maturing, and fully ripe ova in the ovary at a particular time account for asynchronism inTilapia mossambica.

The influence of exposure to low temperature on Tilapia mossambica Peters (Cichlidae).

In the cichlid teleost Tilapia mossambica secondary chill coma following exposure to 11° C in freshwater is associated with decreases in plasma osmolarity, sodium and chloride ion concentrations. Fish exposed in seawater diluted to give a NaCl concentration of 5%0 show no signs of coma nor are there decreases in osmolarity or sodium and chloride ion concentrations.It is suggested that the restrictions of T. mossambica to estuaries at the southern end of its distribution in southern Africa relates to the maintenance of near normal sodium and chloride ion concentrations at low temperatures during winter.

The respiratory metabolism of Tilapia mossambica (Teleostei)

In a series of experiments 174, 120 and 139 individuals of the teleost Tilapia mossambica (Peters), were acclimated to 30°C and to salinities of 0.4, 12.5 and 30.5‰, respectively. The effect of temperature and salinity upon oxygen consumption was studied by abruptly transferring fish of different wet weights to temperatures from 15° to 40°C at an average initial pO2 of 250mm Hg. At each salinity, the proportionate response to temperature is size-independent. The metabolic rate increases as a function of temperature at 15° and 30°C but not at 40°C. Oxygen consumption is, however, salinity dependent; maximum rates are obtained at 12.5‰S. This salinity is isotonic in the 80 g fish and, to a lesser extent, in the 5 g fish. Reduction in osmotic load is suggested as the probable cause for a greater scope for activity and greater rate of oxygen consumption in 12.5‰ salinity.

Regeneration of the caudal neurosecretory system in the cichlid teleost Tilapia mossambica

AbstractAfter total extirpation of the caudal neurosecretory system in the teleost Tilapia mossambica by ligature and removal of the caudal peduncle, a new system regenerates rapidly. The new neurosecretory cells differentiate from ependyma. A series of transitional stages between slightly modified ependymal cells and fully developed caudal neurosecretory neurons can be readily constructed. Immediately after the operation, the distal part of the remaining spinal cord undergoes degeneration, during which no traces of the caudal system can be found. Eleven days after the operation the first signs of the new system appear, and after three weeks a potentially functional, although much reduced, system has developed, the elements of which are detectable with the electron microscope. After 5–6 months, an extensive system has regenerated; however, the neurohemal area equivalent to the normal urophysis is contained within the spinal cord. There is strong cytologic evidence for a considerable release of elementary neurosecretory granules into the cerebrospinal fluid in the regenerating and regenerated system, possibly by several different mechanisms. Prominent tubular reticula occur in the distal (preterminal) parts of the neurosecretory axons, and the possibility of local axonal production of vesicles and granules is strongly supported. Signs of secretion into the central canal and of distal production of neurosecretory material are also present in normal Tilapia, but both phenomena are much more strikingly demonstrated in regenerating systems.

Relation of impulse conduction to electrically induced release of neurosecretory material from the urophysis of the teleost fish Tilapia mossambica.

AbstractThe caudal neurosecretory system of the teleost Tilapia mossambica was subjected in vivo and in vitro to intense and prolonged electrical stimulation. Repeated firing of neurosecretory units was observed in the in vivo preparations, and compound action potentials were recorded in vitro. Evidence of depletion of neurosecretory material from the urophysis was obtained on the light and electron microscope levels. Ultrastructurally two pictures were encountered in the responding axon terminals: (1) a decrease in electron density of most of the elementary neurosecretory granules in individual terminals; (2) complete or nearly complete disappearance of granules and vesicles from individual terminals. The latter picture is considered to be a more advanced stage of depletion.