A. von der Decken

Metabolic effects on growth and muscle of soya-bean protein feeding in cod ( Gadus morhua )

The aim of the present study was to investigate the effect of soya-bean protein on growth and muscle metabolism in fish. Cod, Gadus morhua, were fed on a fish-feed formula with the high-quality fish-meal protein being replaced by 100, 200 or 300 g soya-bean protein/kg fish-meal protein. The feeding experiment lasted for 43 d at a water temperature of 7-8 degrees and a sea water salinity of 3.5%. At the 200 g/kg level of soya-bean protein, food intake and growth rate were similar to those of the controls. At the 300 g/kg level of soya-bean protein, food intake was diminished by 6% and growth by 67% relative to control levels. In muscle, sarcoplasmic protein (/g wet weight) was significantly decreased by 14%. Myofibrillar protein (/g wet weight) was unchanged. Levels of RNA in the myofibrillar fraction decreased at all three levels of soya-bean protein, and that of the sarcoplasmic fraction decreased at the highest level of legume-protein. With increased levels of soya-bean protein, RNA:DNA declined by 18% from 1.88 to 1.54. The contractile protein myosin heavy chain (/mg protein and /g wet weight) and myosin heavy chain-specific mRNA (/mg RNA) were not significantly affected by dietary conditions. Expressed per g wet weight, the decline by 21% of the specific mRNA depended on the total RNA content which decreased with the increase in soya-bean protein. Acid proteinase activity was lowest at the 200 g/kg level, showing a decrease of 23%.(ABSTRACT TRUNCATED AT 250 WORDS)

Vitellogenin synthesis in Atlantic salmon (Salmo salar) at different acclimation temperatures

Abstract Salmon ( Salmo salar ) smolt of 88±7 g body weight were acclimated at 8°C or at 16°C, and presmolt (57±4 g body weight) at 16°C. The fish were injected with 17- β -estradiol, 5 mg/kg body weight, once a week for 2 weeks. In smolt, vitellogenin increased from 9.71±0.68 mg/ml in fish acclimated at 8°C to 27.70±4.05 mg/ml of blood serum in those acclimated at 16°C; in presmolt at 16°C the vitellogenin concentration was 16.41±0.98 mg/ml. Following induction, ribosomal RNA in liver increased significantly with temperature and hormone treatment. The 16°C acclimated smolt responded more than the presmolt acclimated at the same temperature. The Q 10 temperature coefficient for vitellogenin in smolt was 3.71. The Q 10 for the increase in protein synthesis caused by induction was 2.25. The results indicate an increase with temperature of protein synthesis in liver which was followed by a proportionally more extensive rise in vitellogenin concentration in serum.

The effects of branched chain amino-acids upon postoperative muscle protein synthesis and nitrogen balance

Abstract Patients undergoing elective cholecystectomy were given total parenteral nutrition containing adequate amounts of calories and nitrogen postoperatively. One group (n=8) received a solution enriched with branched chain amino-acids (BCAA) and a control group (n=9) was given a balanced amino-acid solution. Muscle biopsy specimens were taken before surgery and on the third postoperative day. Muscle protein synthesis was assessed by comparing the concentration and size distribution of ribosomes between these two occasions. The total ribosome concentration per mg of DNA was decreased by 24% postoperatively at 3 days in both groups as compared with the preoperative value (p

Experimental studies on the quality of food proteins

Abstract 1. 1. This paper reviews chemical and biological assays for measuring the quality of food proteins. 2. 2. The availability of amino acids in a protein is determined by digestability and the capacity of the recipient animal to absorb the amino acids. 3. 3. Intracellularly amino acid concentration influences enzyme activities associated with amino acid and nitrogen metabolism. 4. 4. Amino acids utilized for metabolism affect the cells at the gene level: transcription of DNA to RNA and translation of RNA to protein. 5. 5. More accurate measurements of amino acid utilization for metabolism will follow from further understanding of basic cellular metabolic events.

Sarcoplasmic and myofibrillar proteins in white trunk muscle of salmon (Salmo salar) after estradiol treatment

Abstract 1. 1. Proteins from skeletal muscle of Atlantic salmon ( Salmo salar ) were separated into two fractions, sarcoplasmic and myofibrillar, the sarcoplasmic proteins amounting to 47%. 2. 2. The actomyosin linkage of the myofibrillar proteins was broken by adding ATP MgCl 2 and myosin was brought into solution in high ionic strength buffer. 3. 3. The method was applied to fish treated with 17-β estradiol. The sarcoplasmic protein content per g wet wt or per mg of DNA was unchanged. The myofibrillar proteins decreased by 17%. Myosin heavy chain decreased to a simila extent as the total myofibrillar proteins. 4. 4. The advantage of the methods described is to relate changes in muscle protein metabolism to specific physiological functions of the tissue.

The diurnal pattern of protein synthesis in human skeletal muscle

The diurnal pattern of protein synthesis in skeletal muscle was studied in relation to the serum concentrations of glucose, insulin and cortisol. Twelve healthy volunteers were given an ordinary hospital diet at 4-hourly intervals. The concentration of insulin showed peaks in response to food intake, and that of cortisol decreased over the day. Muscle biopsies were taken 30 min before the first food intake and 1.5 or 3.5 h after a meal. Irrespective of the time intervals after food intake, the total ribosome concentration, percentage amount of polyribosomes and polyribosome concentrations remained unaltered, indicating that there were no alterations in the capacity for protein synthesis accompanying the feeding schedule. The results suggest that a muscle sample taken in the morning after an overnight fast is representative of the protein synthesis during the day as assessed by the ribosome concentration and the size distribution of ribosomes.

Physiological changes in skeletal muscle by maturation-spawning of non-migrating female atlantic salmon, Salmo salar

1. 1. Physiological properties of epaxial muscle of non-migrating female Atlantic salmon (Salmo salar) were compared between non-spawning and spawning fish. 2. 2. The rise in blood plasma vitellogenin, and liver and gonadal weights confirmed the maturation-spawning condition. 3. 3. In the spawning females DNA, glycogen and acid proteinase activity were elevated per g wet weight of muscle, while protein and RNA content of the sarcoplasmic fraction and RNA of the myofibrillar fraction were diminished. 4. 4. The data suggest that characteristic changes occur in skeletal muscle by the process of maturation and spawning, which are independent of the physical load of upstream migration.

Amino acid incorporation into interior protein sites by purified rat liver systems.

M ETHODS have recently been described for the preparation of metabolically active RNP-particles2 from rat liver microsomes [2, 61. These particles readily incorporate labeled amino acids into protein in the presence of a soluble enzyme fraction from rat liver and a nucleoside triphosphate generating system. The particles have been used also in incorporation experiments with “S-RNA”-bound %-amino acids as the labeled precursor [a]. In the presence of soluble liver enzymes and GTP [l] the bound amino acids are rapidly transferred from the S-RNA to particles and incorporated into protein. In experiments with free RNP-particles from peas \Vebster has recently observed that labeled S-RNA-bound amino acids become incorporated only into the N-terminal ends of the growing protein chains [8]. The same was true when free, labeled amino acids were used in incubation systems with pea particles in the absence of a full amino acid complement [9]. The experiments to be described here show that the RNP-particles from liver differ from the pea seedling particles in these respects. Irrespective of whether the labeled amino acids or S-RNA-bound amino acids were added to the incubation system singly, or in the presence of other amino acids, they became incorporated mainly into interior protein sites. Experimental.-The following kinds of incorporation systems were used: (I) Livers from 70-80 g rats were perfused in situ with 0.15 M KC1 and homogenized with 2.5 volumes of an ice-cold medium containing 0.25 M sucrose, 0.025 M KCl, 0.01 M MgCl, and 0.035 M Tris. The homogenate was centrifuged at 12,000 xg for 8 minutes. To each incubation tube 0.8 ml of this mitochondria-free homogenate was added together with 1.3 pmoles of ATP, 13 pmoles of PEP and 0.125 pmoles of 14C-L-valine (8.0 pc/,umole). The tubes (final volumes 1.5 ml) were incubated for 40 minutes (35°C). (2) 1vashed RNP particles were prepared from rat liver microsomes as in previous experiments [2]. The particles were incubated for 30 minutes with 0.5 ml of the

On the possible identity of enzyme requirement in the transfer of sRNA and amino acids to ribosomes

Abstract It has been shown previously ( von der Decken and Hultin, 1958 , Hultin and von der Decken, 1959 ) that in , vivo -labeled sRNA ∗ prepared from rat liver is transferred to the ribonucleoprotein particles of rat liver microsomes. Similar results have also been obtained by Hoagland (1958) and Bosch, Bloemendal and Sluyser (1959) . The sRNA molecules are specific for individual amino acids and current evidence strongly suggests that the various amino acids are transferred by sRNA to the ribosomes. The question of how the ribosomes direct the alignment of amino acids in a specific sequence has been clarified recently. Thus, messenger RNA has the ability to attach itself to the ribosomes and there to determine the sequence of amino acids (Risebrough, Tissieres and Watson, 1962) . Very little is known, however, about a possible interaction between sRNA and messenger RNA when the amino acids are lined up on the ribosomal template during the process of peptidization. One link in this complex system, the enzymic relationship between the transfer of sRNA and of amino acids from sRNA to ribosomal particles, will be described in this paper.

Physiological properties of liver, gonads and muscle during maturation of female atlantic salmon, Salmo salar. Comparison between a control and xenobiotics containing fish feed

1. Atlantic salmon, Salmo salar, in their 4th year were maintained in a sea-based farm in the Baltic Sea, salinity 0.2-0.4%. The fish were fed a control diet or a diet containing, among the lipid-soluble xenobiotics, 60 parts of dioxin per 10(12) parts of fish oil. 2. In the fish that attained sexual maturity the liver and gonadal wet weight increased, but decreased after stripping of the roe. Vitellogenesis was also apparent as an elevated level of plasma vitellogenin which was higher after than 2 months prior to removal of the roe. 3. In muscle protein content was highest prior to the removal of the roe. RNA content decreased with time. Following the taking of the roe glycogen content and acid proteinase activity were elevated. 4. Comparison between the feeding groups showed, in the fish fed the experimental diet, a higher gonadal wet weight and plasma vitellogenin content, and in muscle, after stripping of the roe, a lower glycogen content and an elevated level of acid proteinase activity.