Influence of diet on in vitro and in vivo rates of fatty acid synthesis in coho salmon [Oncorhynchus kisutch (Walbaum)]

The site and the influence of diet on fatty acid synthesis in juvenile coho salmon were investigated. Tritiated water was used to obtain estimates of the rates of fatty acid synthesis. Liver slices and mesenteric glucose and tritiated water. The rate of fatty acid synthesis averaged 1172 +/- 126 and 40 +/- 8 nmoles tritium incorporated into fatty acids per 2 hours per 100 mg of liver and adipose tissue, respectively. The pattern of [1-14C]acetate incorporation into fatty acids in the liver slices indicated that de novo fatty acid synthesis, rather than chain elongation, was occurring. In vivo rates of fatty acid synthesis in liver were approximately linear for 30 minutes. In vivo rates of fatty acid synthesis averaged 244 +/- 14 and 44 +/- 11 dpm of tritium incorporated into fatty acids per 20 minutes per 100 mg of liver and adipose tissue, respectively. Consumption of a high-fat diet or fasting for 2 days decreased the in vitro and in vivo rates of fatty acid synthesis in fish liver. Refeeding fasted (48 hours) fish with a high-carbohydrate diet for 4 hours increased the rate of hepatic fatty acid synthesis. The major site of fatty acid synthesis in coho salmon appears to be the liver, and dietary alterations influence the rate of fatty acid synthesis in the liver.

Effects of fasting and feeding various diets on hepatic lipogenic enzyme activities in coho salmon (Oncorhynchus kisutch (Walbaum))

The influence of fasting and diet composition on the time sequence of changes in hepatic lipogenic enzyme activities in coho salmon was investigated. Young coho salmon fed a high-carbohydrate diet for 3 weeks were then fasted for 2, 6, or 23 days. Liver preparations were assayed for fatty acid synthetase, citrate cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities. Fasting the fish for 2 or 6 days did not influence the activities of these enzymes; however, by the end of the 23-day fast the activities of all these enzymes had decreased. Changing the diet of the fish from high-carbohydrate to high-fat had only a minimal influence on the activities of the hepatic lipogenic enzymes after 7 to 14 days. Longer-term studies demonstrated that high-fat diets did eventually depress lipogenic enzyme activities. The effect of fasting and feeding on the level of lipogenic enzyme activities was observed only after several weeks, in contrast to hours in the rat. This may reflect a difference between poikilothermous and homoiothermous animals.

Influence of dietary lipid on lipogenic enzyme activities in coho salmon, Oncorhynchus kisutch (Walbaum)

Coho salmon (Oncorhynchus kisutch), 8 to 18 months of age, were maintained in culture tanks and were fed three semipurified diets. The diets contained 40% of energy from protein and 11.5%, 23%, or 46% of energy from lipid. The body weight gain and food conversion factors were similar among groups of fish fed the diets in each of the three experiments. Wet weight of mesenteric adipose tissue increased with increased amount of lipid in the diet; however, epaxial muscle lipid content was not influenced by the lipid content of the diet. Several hepatic and adipose tissue lipogenic enzymes (fatty acid synthetase, citrate cleavage enzyme, malic enzyme, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-isocitrate dehydrogenase) were assayed. These lipogenic enzymes exhibited high activities in liver and relatively low concentration in adipose tissue of the fish. The activities of all the hepatic lipogenic enzymes assayed, except for NADP-isocitrate dehydrogenase, were depressed as the level of lipid in the diet was increased; however, the activities of these enzymes in mesenteric adipose tissue were not influenced by the diets fed. The results of this study indicate that dietary lipid depresses hepatic lipogenic enzyme activities and that the liver may be a more important site for fatty acid synthesis than is adipose tissue in coho salmon.

Colony formation in vitro by mouse blood monocytes

Mouse blood monocytes were induced to proliferate and form discrete colonies of mononuclear phagocytes in liquid culutre. The proliferation of these cells in vitro required a factor or factors present in medium conditioned by L cells. For this class of colony-forming cells, the value of Do to gamma irradiation in vitro was 195 rads.

Nuclear magnetic resonance studies of the interaction of general anesthetics with 1,2-dihexadecyl-sn-glycero-3-phosphorylcholine bilayer

Sonicated 1,2-dihexadecyl-sn-glycero-3-phosphorylcholine forms liposomes. Studies by Fourier transform proton magnetic resonance of the interaction of these bilayers with some general anesthetics, i.e., chloroform, halothane, methoxyflurane, and enflurane, show that the addition of a general anesthetic to the liposomes and raising the temperature have a similar effect in cuasing the fluidization of the bilayer. General anesthetics act on the hydrophilic site (choline group) in clinical concentrations and then diffuse into the hydrophobic region with the addition of larger amount of anesthetics. There is evidence that the lecithin choline groups are involved in the interaction with protein and that the general anesthetics change the conformation of some polypeptides and proteins. We conclude that the general anesthetics, by increasing the motion of positively charged choline groups and negatively charged groups in protein, weaken the Coulomb-type interaction and cause the liprotein conformational changes.

The accessory optic fiber system of the golden hamster with special reference to retinohypothalamic projection

The hamster accessory optic fiber system has been investigated with the use of de Olmos-Ingram and Fink-Heimer silver methods following the production of unilateral ocular enucleation. It was found that this fiber system consists of both crossed and uncrossed inferior and superior fasciculi. The fibers of the inferior fasciculus (anterior accessory optic tract) run along the medial edge of the cerebral peduncle and terminate within the medial terminal nucleus of the accessory optic system. The fibers of the superior fasciculus (posterior accessory optic tract) leave the main optic tract, pass superficially over the medial geniculate nucleus and the cerebral peduncle; they synapse within the dorsal, the lateral and the medial terminal accessory optic nuclei. The presence of a retinohypothalamic tract could not be confirmed.

Schedule-dependent effect of phase-specific cytotoxic agents on production of hemolytic plaque-forming cells

The proliferative phase of the primary response of mice to sheep red blood cells (SRBC) was used to study quantitatively the schedule-dependent effect of four phase-specific cytotoxic agents: 1-beta-D-arabinofuranosylcytosine (ARA-C), methotrexate (MTX), 5-fluorodeoxyuridine (5-FUDR), and 5-fluorouracil (5-FU). The multiple injections of ARA-C- GIVEN 24-60 HOURS AFTEr SRBC injection caused a 100-fold greater inhibition in the production of direct hemolytic plaque-forming cells (PFC) on day 4 than the maximum inhibition obtained by a single injection. A similar, but lesser, enhancing effect was observed with 5-FUDR. Although a single injection of either MTX or 5-FU given 24 or 48 hours after the immunization alone was effective in suppressing PFC production, multiple injections of MTX at 6-hour intervals could cause the same degree of inhibition with a smaller total dose. In contrast, there was no difference for 5-FU, whether given as a single injection or in a divided dose. When only two doses of cytotoxic agents were used, 8- and 14-hour intervals with ARA-C and MTX, respectively, gave the maximum degree of inhibition.

Concanavalin A (NSC-143504): its action on experimental tumor cells and possible use in cancer chemotherapy

Concanavalin A administered to mice kills KHT fibrosarcoma tumor cells and, less markedly, AKR lymphoma cells at doses where it has no effect on numbers of normal hematopoietic colony-forming cells. Concanavalin A in vitro agglutinates suspensions of cells prepared from murine and human tumors but does not agglutinate suspensions prepared from most normal mouse tissues. In spite of its selective action against tumor cells at the cellular level, the possibilities for using concanavalin A therapeutically are limited by its unusual toxicity, a generalized vasculitis that is seen in the mouse, monkey, and pig at approximately the same dose level.

On the methylated purine content of tRNA present in tumours

The methylated purine content of tRNA bulk extracted from human hepatomata has been compared with that in normal human liver. The analyses were carried out with the aid of ion-exchange chromatography. The molar proportions of 5 bases detected in acid hydrolysates of tumour tRNA (N(2)-methylguanine, 1-methylguanine, 7-methylguanine, N(2)-dimethylguanine and 1-methyladenine) were not abnormally elevated.