Lipid composition and microsomal ATPase activities in gills and kidneys of warm- and cold-acclimated sea bass (Dicentrarchus labrax L.)

The response to cold of gill and kidney membrane lipid composition and microsomal (Na(+)+K(+))-ATPase, Na(+)-ATPase and Mg(2+)-ATPase activities in reared sea bass (Dicentrarchus labrax L.) was investigated. Fish acclimation was carried out according to the seasonal cycle from August to March. No cold-promoted increase in fatty acid unsaturation was shown in gill and kidney polar lipids and in total lipids of mitochondria and microsomes. In both tissues the (Na(+)+K(+))-ATPase exhibited positive compensation for cold acclimation whereas the Na(+)-ATPase displayed negative compensation. The Mg(2+)-ATPase showed no compensation in the gills and positive compensation in the kidneys. During cold acclimation the break in the Arrhenius plot of the (Na(+)+K(+))-ATPase decreased, whereas breaks of both the Na(+)-ATPase and the Mg(2+)-ATPase activities remained unchanged. The results indicate that the sea bass does not adopt membrane unsaturation as a cold-facing strategy. The cold-promoted enhancement of (Na(+)+K(+))-ATPase activity in osmoregulatory tissues may be advantageous to maintain efficient osmoregulation under thermodynamically unfavourable conditions.

Mammographic aspect, cell kinetics and hormone receptor status of operable breast cancer

To investigate the relationships between the mammographic aspects (according to Broberg), proliferative activity and hormone receptor status, we studied 165 patients subjected to radical mastectomy for operable breast cancer. The highest percentage of estrogen receptor-positive cases was observed in mammograph class I (p < 0.02) while classes III and V were highest in progesterone receptor-positive cases. Proliferative activity (111 cases) was significantly lower in class I and IV with respect to all other classes (p < 0.03 and p < 0.01, respectively). This study suggests that certain mammographic signs can be related to the biological characteristics of breast cancer.

Gill (Na+ + K+)-ATPase involvement and regulation during salmonid adaptation to salt water

1. The involvement of gill (Na+ +K+)-ATPase in salmonid adaptation to salt water (SW) is discussed. 2. Gill (Na+ +K+)-ATPase increase during SW adaptation is mainly related to the increased number and complexity of chloride cells deputed to salt extrusion. 3. The temporal relationships between serum peaks of thyroid hormones, cortisol, growth hormone, prolactin and gill (Na+ +K+)-ATPase rise during salmonid smoltification, suggest a hormonal involvement in the enzyme stimulation and thus in the acquirement of SW tolerance. 4. Literature on gill (Na+ +K+)-ATPase response to hormonal treatment is reviewed. The effects produced on gill (Na+ +K+)-ATPase and chloride cells by exogenous hormones point out a complex inter-relationship between the hormones considered. The mechanisms involved in hormonal regulation of the enzyme remain a matter of debate.

Lipid composition and mitochondrial respiration in warm- and cold-adapted sea bass

The response to cold of liver and heart membrane lipid composition and mitochondrial respiration in reared sea bass (Dicentrarchus labrax L.) was investigated. Fish acclimation was followed during the natural seasonal cycle from August to March. The data on the fatty acid composition of liver and heart polar lipids and on total lipids of liver mitochondria and microsomes did not indicate any increase in unsaturation in response to cold. The enzyme complexes of the liver and heart mitochondrial respiratory chain showed a repeated negative compensation for cold acclimation. The constancy of the break in the Arrhenius plot of liver cytochrome oxidase (EC 1.9.3.1) was consistent with the lack of homeoviscous adaptation of membrane lipids. A thermoadaptive strategy based on the reduction of sea bass metabolic activity is suggested.

[The relationship between the receptor status and the mammographic picture in operable breast cancer]

To verify the relationship of mammographic (Mx) patterns of breast cancer to hormone receptor content (ER, PgR) we studied 129 women (59% in postmenopause; average age 55) in the last 3 years. All women had operable breast cancer and were submitted to mammography before surgery. The tumors were classified, according to Mx characteristics, in 5 classes (Broberg, 1983). ER and PgR contents (cut-off for positivity: 10 fmol/mg prot cyt) were analyzed in all patients by means of DCC method. The percentage of ER+ cases was significantly higher in class I than in all other Mx classes (85% vs 57%; p = 0.02), whereas it was lowest in class IV (51% vs 70%; p = 0.03). The percentage of PgR+ cases was significantly different only in class I with respect to class IV (70% vs 41%; p = 0.002). As for ER and PgR mean tumor content, no statistically significant difference was observed between the 5 classes. When the 2 receptors were simultaneously considered the percentage of ER+ PgR+ cases was higher in class I than in all the extant classes (p = 0.01), and the percentage of ER- PgR- was higher in class IV than in the extant ones (p = 0.02). In selected subgroups of patients, Mx classification of breast cancer can help the physician predict the hormone receptor tumor status with sufficient reliability.

Gill (Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in the gilthead bream (Sparus auratus L.)

1. Gilthead gill 10(-3) M ouabain-inhibited (Na+ + K+)-ATPase and 10(-2) M ouabain-insensitive Na+-ATPase require the optimal conditions of pH 7.0, 160 mM Na+, 20 mM K+, 5 mM MgATP and pH 4.8-5.2, 75 mM Na+, 2.5 mM Mg2+, 1.0 mM ATP, respectively. 2. The main distinctive features between the two activities are confirmed to be optimal pH, the ouabain-sensitivity and the monovalent cation requirement, Na+ plus another cationic species (K+, Rb+, Cs+, NH4+) in the (Na+ + K+)-ATPase and only one species (Na+, K+, Li+, Rb+, Cs+, NH4+ or choline+) in the Na+-ATPase. 3. The aspecific Na+-ATPase activation by monovalent cations, as well as by nucleotide triphosphates, opposed to the (Na+ + K+)-ATPase specificity for ATP and Na+, relates gilthead gill ATPases to lower organism ATPases and differentiates them from mammalian ones. 4. The discrimination between the two activities by the sensitivity to ethacrynic acid, vanadate, furosemide and Ca2+ only partially agrees with the literature. 5. Present findings are viewed on the basis of the ATPase's presumptive physiological role(s) and mutual relationship.

(Na+ + K+)- and Na+-stimulated Mg2+-dependent ATPase activities in kidney of sea bass (Dicentrarchus labrax L.)

1. Sea bass kidney microsomal preparations contain two Mg2+ dependent ATPase activities: the ouabain-sensitive (Na+ + K+)-ATPase and an ouabain-insensitive Na+-ATPase, requiring different assay conditions. The (Na+ + K+)-ATPase under the optimal conditions of pH 7.0, 100 mM Na+, 25 mM K+, 10 mM Mg2+, 5 mM ATP exhibits an average specific activity (S.A.) of 59 mumol Pi/mg protein per hr whereas the Na+-ATPase under the conditions of pH 6.0, 40 mM Na+, 1.5 mM MgATP, 1 mM ouabain has a maximal S.A. of 13.9 mumol Pi/mg protein per hr. 2. The (Na+ + K+)-ATPase is specifically inhibited by ouabain and vanadate; the Na+-ATPase specifically by ethacrynic acid and preferentially by frusemide; both activities are similarly inhibited by Ca2+. 3. The (Na+ + K+)-ATPase is specific for ATP and Na+, whereas the Na+-ATPase hydrolyzes other substrates in the efficiency order ATP greater than GTP greater than CTP greater than UTP and can be activated also by K+, NH4+ or Li+. 4. Minor differences between the two activities lie in the affinity for Na+, Mg2+, ATP and in the thermosensitivity. 5. The comparison between the two activities and with what has been reported in the literature only partly agree with our findings. It tentatively suggests that on the one hand two separate enzymes exist which are related to Na+ transport and, on the other, a distinct modulation in vivo in different tissues.

Effect of diets containing different oils on brain fatty acid composition in sea bass (Dicentrarchus labrax L.)

Four groups of adult sea bass were given diets containing about 8% of one of four different oils having a different fatty acid composition: linseed oil, grape-seed oil, containing high amounts of linolenic and linoleic acids respectively, hydrogenated coconut oil, mainly containing saturated fatty acids, and cod liver oil which was considered as reference. Total lipid, phospholipid and polar lipid contents of the brain of the different groups of sea bass were unaffected. The fatty acid composition of the brain agreed with the dietary history of sea bass: thus adult sea bass brain is capable of incorporating dietary fatty acids. Sea bass brain and structural lipids of the liver appeared to be similarly sensitive to the dietary input in contrast with mammalian brain which was reported to be more resistant than other tissues. The more striking dietary effect on liver total lipid fatty acid composition is ascribed to the incorporation of dietary fatty acids in depot fats.

Ouabain-insensitive Na+ stimulation of a microsomal Mg2+ -ATPase in gills of sea bass (Dicentrarchus labrax L.)

Bass gill microsomal preparations contain a Mg2+-dependent Na+-stimulated ATPase activity in the absence of K+, whose characteristics are compared with those of the (Na+ + K+)-ATPase of the same preparations. The activity at 30 degrees C is 11.3 mumol Pi X mg-1 protein X hr-1 under optimal conditions (5 mM MgATP, 75 mM Na+, 75 mM HEPES, pH 6.0) and exhibits a lower pH optimum than the (Na+ + K+)-ATPase. The Na+ stimulation of ATPase is only 17% inhibited by 10-3M ouabain and completely abolished by 2.5 mM ethacrinic acid which on the contrary cause, respectively, 100% and 34% inhibition of the (Na+ + K+)-ATPase. Both Na+-and (Na+ + K+)-stimulated activities can hydrolyze nucleotides other than ATP in the efficiency order ATP greater than CTP greater than UTP greater than GTP and ATP greater than CTP greater than GPT greater than UTP, respectively. In the presence of 10(-3)M ouabain millimolar concentrations of K+ ion lower the Na+ activation (90% inhibition at 40 mM K+). The Na+-ATPase is less sensitive than (Na+ + K+)-ATPase to the Ca2+ induced inhibition as the former is only 57.5% inhibited by a concentration of 1 X 10(-2)M which completely suppresses the latter. The thermosensitivity follows the order Mg2+--greater than (Na+ + K+)--greater than Na+-ATPase. A similar break of the Arrhenius plot of the three enzymes is found. Only some of these characteristics do coincide with those of a Na+-ATPase described elsewhere. A presumptive physiological role of Na+-ATPase activity in seawater adapted teleost gills is suggested.

[First observations on the effect of various dietary oils on liver fatty acids in bass (Dicentrarchus labrax)]

A close relationship between dietary oils and fatty acid composition of bass liver and liver microsomes and mitochondria is reported in the present paper. Among the data the most relevant is the evidence for elongation and desaturation of dietary 18:3 n-3 and 18:2 n-6, giving as a result an increase of 22:6 n-3 and 20:4 n-6 levels respectively. The importance of such findings in carnivore marine fish is discussed and compared with literature data.

[Na+-ATPase in the gills of bass (Dicentrarchus labrax)]

The authors evidence a Mg2+ dependent ATPase activity stimulated by Na+ in absence of K+ in bass gill microsomes. As this stimulated ATPase shows different features from "baseline" activity measured in the absence of both Na+ and K+ ions (Mg2+-ATPase) and from 1mM ouabain sensitive (Na+ + K+)-ATPase, it has been ascribed to a distinct Na+-ATPase. In the present paper the optimal conditions for bass gill Na+-ATPase assay and the temperature dependence of the enzyme are reported. Moreover the Na+-ATPase appears to be insensitive to 1mM ouabain and 100% inhibited by 2,5mM ethacrynic acid. It is suggested a parallel diffusion of Na+- and (Na+ + K+)-ATPase and a possible physiological role of Na+ATPase in osmoregulation.

[Characteristics of (Na+ + K+)-ATPase in the gills of bass]

A partial characterization of bass gill (Na+ + K+-ATPase is reported in the present paper. Microsomal preparation from gill homogenate showed optimal (Na+ + K+)-ATPase activity at pH 6,5 in the presence of 100 mM Na+, 20mM K+ and 5mM Mg2+. Under these conditions maximal activity was shown at 45 degrees C, even if an increased lability of the enzyme was shown at temperature greater than 30 degrees C. A complete inhibition of the enzyme occurred in the presence of 1 mM ouabain. The break in the Arrhenius plot occurred approximatively at the temperature of adaptation of these fish (18 degrees C). The energies of activation above and below the break were scarcely different from each other and lower than those reported in other Poikilotherms. Furthermore similar values of Km for Na+ were evidenced at 18 degrees C and 30 degrees C. The whole of data are discussed in comparison with other teleost gill (Na+ + K+)-ATPase reports and related to the physiological role of the enzyme in osmoregulation.

[Arrhenius diagrams of respiratory enzymes of liver mitochondria from bass (Morone labrax)]

Arrhenius plot of glutamate, succinate and ascorbate+TMPD oxidation in bass liver mitochondria show a break at different temperatures. Above the break activation energies (Ea) of the three enzymes. Above the break activation energies (Ea) of the three enzymes examined are similar and comparable with literature data in poikilotermic and homeothermic animals. Below the break the Ea are again comparable with poikiloterm and homeotherm ones except for succinate-oxidase whose Ea is surprisingly higher. The data are suggested to be due to the features of the enzymes or to the microenvironmental physical state.

[Respiration and oxidative phosphorylation in liver mitochondria of bass (Morone labrax) and their dependence on temperature]

In the present paper the respiratory function in bass liver mitochondria is studied over the temperature range 6-34 degrees C. The respiratory rate in state 3 and state 4 at the temperatures examined agrees with data from poikiloterms reported elsewhere by other investigators ICR and ADP/O values with glutamate and succinate as substrates are considered and their variations as a function of the experimental temperature are discussed. ICR shows a maximum at 20 degrees C which approximatively corresponds with the temperature of the seawater where these fishes were bred. On the contrary ADP/O ratio does not show any meaningful variation.

[Interaction of n-alkanes with respiration and oxidative phosphorylation in rabbit heart mitochondria: n-nonane]

Studies "in vitro" on the effect of n-nonane on coupled rabbit heart mitochondria with both succinate and glutamate as substrates show that the hydrocarbon examined makes the membrane permeable to protons (uncoupling), to some matrix enzymes and to exogenous NADH. The effect increases with increasing n-alkane concentration (from 0 to 160 microgram/mg mitochondrial protein) and temperature (from 15 degrees to 38 degrees C). Furthermore at higher concentrations and temperatures NADH oxidase inhibition is observed, whereas on succinate oxidase a biphasic effect (activation at lower concentrations and inhibition at higher concentrations) is produced. However the results, qualitatively similar to those observed with n-hexane, exhibit features probably due to a longer chain and that can be ascribed to perturbations of the physical state of membrane lipids.

[Interaction of n-alkanes with respiration and oxidative phosphorylation in rabbit heart mitochondria: n-hexane]

n-Hexane on coupled rabbit heart mitochondria induces "in vitro" uncoupling with both glutamate and succinate as substrates and the effect increases with increasing n-alkane concentration (from 0 to 160 microgram/mg mitochondrial protein) and temperature (from 15 degrees to 38 degrees C). The inner mitochondrial membrane is made permeable to proteins; moreover extrusion of some matrix enzymes and entry of exogenous NADH is produced. Furthermore at higher concentrations and temperatures NADH oxidase inhibition and increase of its thermosensitivity is shown whereas upon succinate oxidase is evidenced a biphasic effect (activation followed by inhibition). The results, qualitatively similar to those observed with detergents and solvents, suggest a fluidization of the lipid phase of the membrane.

[Interaction of n-alkanes with respiration and oxidative phosphorylation in rabbit heart mitochondria: n-dodecane, n-pentadecane and n-octadecane]

The effect of n-dodecane, n-pentadecane and n-octadecane at various concentrations (from 0 to 160 microgram/mg mitochondrial protein) and temperatures (from 15 degrees to 38 degrees C) is studied "in vitro" on coupled rabbit heart mitochondria. With both glutamate and succinate as substrates, and at higher temperatures only, n-dodecane makes the membrane permeable to protons (uncoupling), to some matrix enzymes and poorly to NADH; moreover it slightly inhibits NADH-oxidase and exerts a biphasic action (activation followed by inhibition) on succinate oxidase. The results, qualitatively similar to those observed with n-hexane and n-nonane, are yet less striking and exhibit features probably due to the longer chain. The other n-alkanes examined do not show any effect.

[Unusual fatty acids in turkeys fed a diet containing "Toprina". III. Composition of higher fatty acids in the heart and skeletal muscle]

Total lipids (TL), phospholipids (PL) and fatty acid composition of TL and PL were estimated in breast, leg and cardiac muscles of turkeys, males and females, fede diets containing 0%, 10% and 15% of Candida lipolytica cultivated on n-alkanes by industrial method ("Toprina"). LT and PL were also valued in "Toprina" and diets. With increasing concentration of dietary yeasts it was observed that: a) Pl increased in diets, breast and leg muscles; b) fatty acids 15:0 and 17:0 increased, 17:1 and 17:2, typical of the product, appeared and increased in the tissues.

[Unusual fatty acids in turkeys fed a diet containing "Toprina". II. Composition of the higher fatty acids of the liver, brain and adipose tissue]

Total lipids (TL), phospholipids (PL) and fatty acid composition of TL and PL were estimated in adipose tissue, liver and brain of turkeys, males and females, fed diets containing 0%, 10% and 15% of Candida lipolytica cultivated on n-alkanes by industrial metod ("Toprina"). TL and PL were also valued in "Toprina" and diets. It was observed that: a) PL increased in diets, adipose tissue and liver, not in brain; b) with increasing concentrations of dietary yeasts fatty acids 15:0 and 17:0 increased, 17:1 and 17:2 typical of product appeared and increased in adipose tissue and liver only, not in brain.

[Unusual fatty acids in turkeys fed a diet containing "Toprina". I. Composition of the higher fatty acids in "Toprina", the diet, feces and blood]

Totals lipids (TL) phospholipids (PL) and fatty acid composition of TL and PL (the latter in blood only) were estimated in Candida lipolytica cultivated on n-alkanes by industrial method ("Toprina"), in 0%, 10% and 15% "Toprina" diets and in faeces and blood of turkeys, males and females, fed these diets. With increasing concentrations of dietary "Toprina" phospholipids and 15:0 and 17:0 fatty acids increased, 17:1 and 17:2, typical of the product, appeared and increased in diets and blood. Other lipid and fatty acids values were not affected by dietary yeast.