The high intracellular ph buffering of hagfish (Eptatretus cirrhatus) dental plate retractor muscle cannot be attributed to the known histidine-related compounds present in other vertebrates

• 1.1. Intracellular pH buffering capacity of hagfish (Eplatretus cirrhatus) dental plate retractor muscles is among the highest reported for any vertebrate muscle.
• 2.2. Over 80% of the pH buffering capacity of hagfish retractor and myotome muscle is due to components other than proteins and phosphate.
• 3.3. The muscles have less than 0.5 μmol/g wet weight of l-histidine, and lack l-l-methyl histidine, l-3-methyl histidine and the histidine-containing dipeptides anserine, carnosine and ophidine.
• 4.4. Instead, they contain an unidentified low molecular weight acid-soluble compound to which the high pH buffering capacity can be attributed.

     

Human urinary excretion of l-histidine-related compounds after ingestion of several meats and fish muscle

• 1.1. After oral administration of the muscle of skipjack tuna, about 90% of ingested anserine (Ans) was excreted quickly into urine as Ans (8%) and π-methylHis (82%), indicating the fast decomposition of Ans into π-methylHis. This was also the case for chicken muscle ingestion.
• 2.2. After eel muscle ingestion, carnosine (Car) excretion was only 1 % of the ingested whereas almost no increase was found in His, a constituent of Car, indicating the re-utilization of this essential amino acid. Similar results were also obtained from beef and pork ingestion.
• 3.3. In all cases, the urinary excretion of these compounds reached a maximum within 7 hr after ingestion and returned to the level of meat-free diet within 40 hr.

     

Electrolyte changes,cell volume regulation and hormonal influences during acclimation of rainbow trout (Salmo gairdnerii) to salt water

• 1.1. Rainbow trout were acclimated to salt water (1.5, 2.0 or 3.0%, which means 40, 60 or 85% concentrated sea-water) and the electrolyte, glucose and cortisol concentrations of the plasma as well as the extra- and intracellular muscle space, the muscle electrolyte concentrations and the ATPase activity were analysed.
• 2.2. Plasma osmolality, Na⁺, Ca²⁺ and Mg²⁺ concentrations of the plasma had a maximum at 24 hr after the start of acclimation when acclimated to 3.0% salt water. Plasma osmolality, Na⁺ and Mg²⁺ concentrations were significantly higher during the whole acclimation time when exposed to 3.0% salt water.
• 3.3. Variations and regulations of ECS and ICS were clearly demonstrated. The intracellular electrolyte concentrations were also maximal at 24 hr.
• 4.4. The plasma glucose level was just slightly elevated, but the cortisol level clearly indicated a stress response at 24 hr.
• 5.5. The activity of gill Na-K-ATPase increased during the acclimation time.
• 6.6. The regulatory processes in trout during acclimation to salt water are compared with those occurring in tilapia and carp.

     

Does carnosine possess direct antioxidant activity?

• 1.1. A brief review of development of ideas of the antioxidant activity of carnosine and related compounds is presented.
• 2.2. An analysis of the behaviour of carnosine in different models of free radical chain reactions shows that carnosine is a potent hydrophylic antioxidant of a direct non-enzymatic action.
• 3.3. It is characteristic of the higher activity of interaction with active hydroxyl radical.
• 4.4. However the known biological effects of carnosine cannot be explained only by its anti-oxidant properties.

     

Hyperosmotic properties of the fluids of the perivisceral coelom and water vascular system of starfish kept under stable conditions

• 1.1. Osmotic measurements were made on the perivisceral coelomic and water vascular fluids of 4 species of northwest Pacific starfish and their stable sea-water media.
• 2.2. Mean levels of both fluids were hyperosmotic in every species, often at statistically significant levels.
• 3.3. For all species combined, mean hyperosmolality (mosmol/kg ± SE) of perivisceral coelomic fluid was 1.49 ± 0.17, and water vascular fluid 6.07 ± 0.74.
• 4.4. The hyperosmotic nature of these fluids contributes to water balance, working in conjunction with madreporitic inflow and other factors.

     

Osmotic regulation in aqueous humor and blood in the euryhaline fish,Eugerres plumieri

• 1.1. The estuarine fish Eugerres plumieri was acclimated to sea-water concentrations ranging from 6 to 85% sea-water.
• 2.2. Serum and aqueous humor osmolalities were moderately well regulated over the range of concentrations studied.
• 3.3. Serum osmolality and aqueous humor osmolalities conformed to the following relations: serum osmolality = (319 ± 3) + (0.56 ± 0.03) (% sea-water); aqueous humor osmolality = (314 ± 4) + (0.35 ± 0.04) (% sea-water).
• 4.4. Aqueous humor osmolality was more strictly regulated than that of serum, indicating that the retina and nervous system of the fish, which are encased in inextensible structures, are well protected from variations in sea-water concentration in order to minimize osmotically induced changes in cell volume.

     

Protein digestion and ion concentrations in rainbow trout (Salmo gairdnerii Rich.) digestive tract in sea- and fresh water

• 1.1. Rainbow trout maintained in fresh water or Actapted to sea-water for 24 hr were fed casein-based dry diet. After feeding, fish were kept in fresh water (FW) or transferred to artificial sea-water (SW) and sacrificed after 10 or 20 hr.
• 2.2. The digestive tract was separated into five parts: stomach, pyloric caeca region, middle intestine and two equal lengths of rectum.
• 3.3. The content of these parts was analysed for ions Na⁺, K⁺, Cl⁻, Mg²⁺ and for free, peptide and total amino acids.
• 4.4. In the fish stomach all ions, with the exception of Ca²⁺, indicate drinking of sea-water. In the pyloric caeca region Na⁺ appears to be efficiently absorbed in SW fish but influxed in FW fish. In the rectum of SW fish K⁺ appears to be reabsorbed but Na⁺ concentrated in faeces.
• 5.5. Free amino acid concentrations were always higher in gut lumen of SW than in FW fish in respect to time after feeding and portion of intestinal content. Free amino acids constitute at most 7.4–8.7% of total amino acids in the content of pyloric caeca region.
• 6.6. Peptide amino acids, being mostly di-, tri- and tetra-peptides, increased in stomach content from 14.7 to 28.4% of the total, from 6 to 10 hr after a meal in SW fish. Peptide amino acids constituted 80.3–89.0% of total amino acids in intestinal content of the pyloric caeca region. These peptide portions decreased in the mid-intestine (47.5–52.5%) and increased again in the rectum (73.6–76.0%).
• 7.7. It was concluded that in rainbow trout fed in both sea- or fresh water, ion concentrations do not seem to interfere with protein digestion and nutrient absorption in alimentary tract.

     

Short-term osmotic responses of cells and tissues of the sea anemone,Condylactis gigantea

• 1.1. Cells of tentacles and body wall of the sea anemone Condylactis gigantea behaved as simple osmometers during 5hr exposure to 50, 67, 83, 100 and 125% sea-water.
• 2.2. All intracellular water appeared to be osmotically active.
• 3.3. Cell sodium, chloride and total osmolyte content remained invariable, with taurine decreasing and potassium increasing as sea-water concentration was reduced.
• 4.4. Tissues, as a whole, exhibited a pseudoregulatory response to changes in salinity as the large and osmotically inert extracellular space buffered volume changes to a considerable extent.

     

Sea-water tolerance in freshwater-resident arctic charr (Salvelinus alpinus)

• 1.1. Freshwater-resident Arctic charr acclimated for 2 months at 8°C, 15% were divided into four experimental groups in July and exposed to 1 and 8°C in 15 and 34% salinity.
• 2.2. Only slight changes in gill Na-K-ATPase activity, blood plasma osmolality and blood plasma concentrations of Cl⁻ and Mg²⁺ were found for the fish exposed to 1 or 8°C in brackish water.
• 3.3. When exposed to sea-water at 8°C, an increase in osmolality and in concentrations of Cl⁻ and Mg²⁺ took place during the first 2–3 days, after which it levelled off.
• 4.4. If exposed to sea-water at 1°C, however, marked increases were found for all parameters measured and all the fish were dead within 5 days of exposure.
• 5.5. These results show that freshwater-resident Arctic charr—if acclimated to brackish water—can survive in sea-water during summer if the environmental temperature is not too low.

     

Potassium balance in freshwater-adapted xtrout Oncorhynchus mykiss

• 1.1. Potassium loss occurs through the gills of trout.
• 2.2. This loss is compensated by intestinal absorption.
• 3.3. During a fasting period, branchial regulation appears after 2–3 days.
• 4.4. The maintenance of potassium balance is discussed as a function of experimental conditions.

     

Purification and characterization of elastase from the pyloric caeca of rainbow trout (Oncorhynchus mykiss)

• 1.1. An elastase-like enzyme was purified from the pyloric caeca of rainbow trout by hydrophobic interaction, cation exchange and gel-filtration chromatography.
• 2.2. The approximate molecular weight of the elastase was 27 kDa and the isoelectric point was remarkably basic.
• 3.3. The pH optimum of this enzyme was 8.0, when assayed with Succinyl-Ala-Ala-Ala-p-Nitroanilide.
• 4.4. When assayed with Succinyl-Ala-Ala-Ala-p-Nitroanilide, the enzyme activity had a temperature optimum of 45°C, and the enzyme was stable up to this temperature.
• 5.5. The trout elastase exhibited a higher specific activity than porcine elastase against Succinyl-Ala-Ala-Ala-p-Nitroanilide and elastin-orcein.
• 6.6. The trout elastase was inhibited by elastatinal, PMSF, TPCK, SBTI and Bowman-Birk inhibitor.

     

Detection of 180 kDa proteins in electroplax sodium channel preparations

• 1.1. Co-isolating proteins (M_r 170,000–220,000) from sodium channel preparations made from the electric organ of the electric eel (Electrophorus electricus) were detected on Western blots using monoclonal a antibodies.
• 2.2. Similar protein patterns were seen on immunoblots containing immunoprecipitated protein from eel muscle and brain tissues but not heart.
• 3.3. These co-isolating proteins could be separated from the mature TTX-sensitive channel protein (M_r 280,000) using a lentil lectin-Sepharose column.
• 4.4. The 180 kDa proteins do not appear to be channel-related and can be detected as contaminants in electroplax sodium channel preparations using the monoclonal antibodies described here.

     

Changes of the fatty acid composition in smolts of masu salmon (Oncorhynchus masou), associated with desmoltification and sea-water transfer

• 1.1. Tissue lipid compositions of desmoltified yearlings of masu salmon (Oncorhynchus masou) obtained by keeping smoltified fish in fresh water, were examined and compared to those of smoltified fish before and after transfer to sea-water (SW).
• 2.2. Lipid contents of muscle, liver, gut and gills of desmolts tended to increase compared to those of initial smolts.
• 3.3. The increased proportion of triacylglycerol (TG) and decreased proportion of phospholipids (PL) characterized the tissue lipids of desmolts.
• 4.4. Liver and muscle lipids showed no distinct differences both in content and proportion between initial and SW smolts, but gut and gill lipids of SW smolts decreased in content accompanied by a decrease of TG and an increase of PL in proportion.
• 5.5. Excepting muscle non-polar lipids, tissue lipids of desmolts contained more mono-unsaturated fatty acids and saturated fatty acids and less polyunsaturated fatty acids (PUFA), especially (n-3) PUFA such as 22:6(n-3), than those of initial and SW smolts.
• 6.6. No large differences in fatty acid composition were seen between initial and SW smolts except for the gut.
• 7.7. The proportion of (n-3) PUFA in the gut of SW smolts was higher than that of initial smolts.
• 8.8. The results indicated that masu salmon smolts can modify their lipid metabolism to adapt to ambient salinity changes. The proportion of (n-3) PUFA particularly in polar lipids, or in osmoregulatory organs such as gut and gills, was seen to be critical in lipid types of freshwater- or sea-water-adapted fish.

     

A simple procedure for evaluating the protein degradation rate in mussel (Mytilus galloprovincialis Lam.) tissues and its application in a study of phenanthrene effects on protein catabolism

• 1.1. An improved, simple method for the evaluation of the protein catabolic rate in the tissues of the lamellibranch mollusc Mytilus galloprovincialis Lam. is presented.
• 2.2. This procedure, which utilizes the technique of the decay curve of a labeled amino acid (¹⁴C-leucine) in the tissues, exploits the capacity of these organisms to rapidly take up soluble compounds from sea-water.
• 3.3. When mussels are exposed to ¹⁴C-leucine in the sea-water, the labeled amino acid is rapidly accumulated into the cell proteins.
• 4.4. A further addition of unlabeled leucine to the sea-water drastically decreases the specific activity of soluble amino acids into the cells, so that the reincorporation of the labeled leucine into the proteins becomes negligible, allowing a correct estimation of the degradation rate of the proteins.
• 5.5. This procedure was utilized to evaluate the effect of phenanthrene on the rate of catabolism of cytosolic proteins in the digestive gland of mussels, and to study the relationship between the protein degradation rate and the activity of lysosomes, which play a well-established role in the catabolism of macromolecules.

     

Mechanical properties of the stalk and cirri of the sea lily Cenocrinus asterius

• 1.1. The mechanical properties of the stalk and cirri of Cenocrinus asterius L. were analysed using freshly autotomized stalk segments.
• 2.2. When tested in bending, the proximal portions of the stalk had a lower flexural stiffness than the medial/distal portions. The difference between the proximal and medial/distal regions was less than an order of magnitude.
• 3.3. The rate of plastic deformation (creep) of stalk segments and cirri subjected to a constant load was used to calculate the coefficient of viscosity. Measurements taken while the samples were bathed in sea-water, distilled water, or potassium enriched sea-water produced no obvious differences in the viscous properties of the samples.

     

Variations in tissue reserves,plasma metabolites and pancreatic hormones during fasting in immature carp (Cyprinus carpio)

• 1.1. Immature carp were subjected to 2-month fasting periods. Mobilization of reserves in liver and muscle, and the energy contribution of each reserve were studied. Changes in plasma glucose, amino acids, insulin and glucagon levels were determined throughout the experiment.
• 2.2. No changes were observed in plasma glucose, insulin or glucagon at 19 days of fasting, but plasma amino acids increased. At 50 days of fasting, both plasma glucagon and amino acids increased, liver glycogen decreased and muscle proteolysis began.
• 3.3. Between 50 and 67 days of fasting, plasma glucose and insulin decreased significantly, while glucagon and amino acids continued to increase. Strong muscular proteolysis was observed while liver glycogen stabilized.
• 4.4. The contribution of each reserve in liver and muscle to energy production throughout fasting is considered.

     

Adaptation of rainbow trout (Salmo gairdnerii) to sea water: Changes in calcitonin levels

• 1.1. The calcitonin content of the ultimobranchial body (UBB) and plasma levels of calcitonin, calcium and phosphate were measured in rainbow trout (Salmo gairdnerii) following their transfer from fresh to sea water.
• 2.2. The plasma calcium level remained unchanged throughout the experiment while the UBB calcitonin content, plasma calcitonin and plasma phosphate rose significantly during the hours immediately following transfer.
• 3.3. The levels of all three subsequently fall so that, 8–15 days later, a new equilibrium was established with lower than control (fresh water) levels of UBB calcitonin, plasma calcitonin and plasma phosphate.
• 4.4. It would appear, from these data, that calcitonin plays some part in the endocrine regulation of sea water transfer.

     

Varying amounts of stretch stimulus regulate stretch-induced muscle hypertrophy in the chicken

• 1.1. The effects of different amounts of passive stretch per day and number of days of stretch on muscle hypertrophy in the chicken patagialis (PAT) muscle were determined.
• 2.2. Stretch for 24 hr per day (h/d) resulted in a more rapid hypertrophy both on a wet and dry tissue basis (P < 0.001) than stretch for 4 h/d.
• 3.3. Stretch increased PAT weight 43% and 25% in 24 h/d and 4 h/d treatments, respectively, after 10 days of stretch, but by day 25 of stretch there was no difference between treatments.
• 4.4. In a second experiment, the PAT muscle was hypertrophied and then the effects of intermittent stretch (4 h/d) on regression of hypertrophy (muscle atrophy) were investigated.
• 5.5. Intermittent stretch (4 h/d) for 5 and 10 d significantly (P < 0.001) inhibited regression of hypertrophied muscle.
• 6.6. The results of the present study indicate that stretch-induced hypertrophy can be modulated by varying the amount of stretch applied per day.
• 7.7. Intermittent stretch can be used to inhibit the regression which occurs when a continuous stretch stimulus is removed.
• 8.8. Intermittent stretch is a useful model for investigating mechanisms of muscle hypertrophy and inhibition of muscle atrophy.

     

Salt-dependent effects of juvenile hormone and related compounds in larvae of the brine shrimp,Artemia

• 1.1. Molting in state III larvae of the brine shrimp. Anemia, is interrupted, or even accelerated, when populations are exposed to various concentrations of juvenile hormone, methyl farnesoate, or methoprene in artificial sea-water.
• 2.2. The effects are believed to be salt-dependent, because exposure to these compounds in sea-water that is isotonic to larval hemolymph had no effect. This suggests that the juvenoids may target the ion transporting epithelia.

     

Sodium balance in adult atlantic salmon (Salmo salar L.) during migration into neutral and acid fresh water

• 1.1. In sea-water, adult salmon (S. salar) exchange an average of 12.6% of total body sodium/hr.
• 2.2. Following transfer to fresh water sodium uptake follows Michaelis-Menton kinetics. F_max = 2.40 mmol Na/1 ECF/hr, K_m = 0.26 mmol Na/1. The uptake system is fully activated immediately following transfer to fresh water.
• 3.3. Post smolts adapted to sea-water for 3 months take up sodium at only one third of the rate of adult fish following return to fresh water.
• 4.4. The concentration of prolactin in the plasma is low in sea-water adapted fish and does not rise during the first 8 hr in fresh water.
• 5.5. At pH 5 sodium uptake is reduced by almost 90%, even in the absence of aluminium, but recovers immediately on return to neutral water.
• 6.6. At pH 5 and 20 μmol Al/1 there is little further effect on sodium uptake but after 6 hr in aluminium the inhibition of sodium uptake continues after return to neutral aluminium fresh water and uptake is only 50% of normal 24 hr later.