Alteration of liver microsomal proteins from rainbow trout (Salmo gairdneri) fed cyclopropenoid fatty acids

Rainbow trout were fed diets containing cyclopropenoid fatty acids (CPFA) at 50 and 300 ppm with appropriate controls fed CPFA-free diets. Treatment with CPFA altered the overall microsomal protein composition in a manner suggesting a reduction of high molecular weight components. One protein found in low concentration in controls appeared dominant in experimental animals, with the effect more pronounced as dietary levels of CPFA increased. The estimated molecular weight of this component was 41,500 daltons. Membrane fractions from CPFA-fed fish separated on a Bio-Gel P-150 column revealed a significant number of small molecular weight components that suggest degradation of microsomal proteins. These data suggest an alteration by CPFA of membrane protein composition.     

Bile acid composition of rainbow trout,Salmo gairdneri

The bile acid composition and metabolism of rainbow troutSalmo gairdneri has been investigated by thin layer chromatography, gas liquid chromatography, and radio gas liquid chromatography methods. For this purpose gallbladder bile was collected from fed fish at 6 and 13 months and from starved fish at 12 months of age. Cholic acid was found to be the main component and constituted over 85% of total. Chenodeoxycholic acid accounted for 14% or less and the 3α, 12α-7-keto- and 7α, 12α-3-keto-5β-cholanoates for 1% or less of total. The bile acids were conjugated mainly with taurine, only small amounts of glycocholic acid being detected. Ca. 5% of the taurocholate was sulfated, as were trace amounts of cholic and glycocholic acids. The size of the bile acid pool was found to increase in the older fish and to decrease in starved fish. Unlike mammalian livers, the livers of the trout converted radioactive chenodeoxycholic acid into cholic acid.     

Effect of dietary linolenic and linoleic acids upon growth and lipid metabolism of rainbow trout (Salmo gairdneri)

Nine diets, each containing different levels of linoleic acid (18∶2ω6) and linolenic (18∶3ω3) were fed to duplicate groups of rainbow trout for 14 weeks. The growth rate, feed efficiency, accumulated mortality, and fatty acid composition of neutral fat and phospholipids of these groups of fish were determined. The growth was slow in the groups of fish receiving diets containing (A) low concentration of 18∶3ω3 and (B) high concentration (5%) of 18∶2ω6. The accumulated mortality was high in these groups of fish. The diet containing 1% 18∶3ω3 alone supported rapid fish growth with low mortality. The feed efficiency of this diet was also high. The metabolism of 18∶2ω6 and 18∶3ω3 in fish and their conversion to more unsaturated fatty acids typical of fish lipids was investigated.     

Effect of dietary lipids on fatty acid composition of body lipid in rainbow trout (Salmo gairdneri)

Three isocaloric diets were prepared. Diet 1 (Control) contained 22% herring oil. In diets 2 and 3, a third and a half of the herring oil was replaced, respectively, by an animal fat (lard) which contained a high percentage of saturated fatty acids. Each diet was fed to duplicate groups of rainbow trout for 14 wk. The results of the feeding trial indicated that the concentration of the saturated fatty acids in trout body lipid did not increase despite the high concentration of these fatty acids in Diets 2 and 3. Fish growth, feed efficiency, mortality and the level of fatty acid deposited in fish body lipid and phospholipids are discussed. Technical Paper No. 4440, Oregon Agricultural Experiment Station, Oregon State University, Corvallis, OR 97331.     

Effect of dietary linolenic acid and docosahexaenoic acid on growth and fatty acid composition of rainbow trout (Salmo gairdneri)

Methyl linolenate 18∶3ω3 and docosahexaenoate 22∶6ω3 were incorporated in semipurified diets at several levels and fed to trout previously maintained on a fat-free diet. After 14 weeks, the weight gain and feed conversion of the fish on each diet were determined. The fatty acid composition of the lipid from each group of fish was analyzed by gas liquid chromatography. Both 18∶3ω3 and 22∶6ω3 fed at the 1% level supported maximum growth of the fish. The control group, which were fed no ω3 fatty acids, exhibited a shock syndrome, poor appetite and a very slow growth rate. Tissue fatty acid analysis revealed eicosatrienoic acid 20∶3ω9 accumulated in the phospholipid fraction of this group. The 20∶3ω9 level was lowered when either 18∶3ω3 or 22∶6ω3 was included in the diet. Analysis showed that the dietary 18∶3ω3 was rapidly converted by the fish into 22∶6ω3 with a high concentration in the phospholipid. However 22∶6ω3 fed to the fish remained unchanged and little or no retroconversion of this fatty acid was observed. Presented in part at the AOCS Meeting, Atlantic City, October 1971. Technical paper no. 3247, Oregon Agricultural Experiment Station.     

Reproduction and survival of rainbow trout (Salmo gairdneri) fed linolenic acid as the only source of essential fatty acids

A semipurified test diet containing 1% linolenate as the sole dietary essential fatty acid was fed to a group of rainbow trout (Salmo gairdneri) for 34 months. The fish matured and the eggs produced were hatched. The second generation fry were fed our laboratory diet for 3 months. The growth of these fry was normal. Histologic examinations revealed no abnormality in liver, heart and kidney tissues of the fry during the three month period. Technical Paper No. 5011, Oregon Agricultural Experiment Station, Oregon State University, Corvallis, Oregon 97331.     

Partial purification of a triacylglycerol lipase isolated from steelhead trout (Salmo gairdneri) adipose tissue

A triacylglycerol (TG) lipase (EC 3.1.1.2), assayed by monitoring [1-¹⁴C]-oleic acid release from [carboxyl-¹⁴C]-triolein after liquid-liquid partition of the fatty acid from the unhydrolyzed triacylglycerol substrate, was isolated and partially purified from steelhead trout adipose tissue. The TG lipase was resolved from contaminating lipoprotein lipase by heparin-sepharose affinity chromatography and purified ca. 71-fold over the original fraction. Optimal enzyme activity occurred at pH 7.5. The purified enzyme migrated on SDS-polyacrylamide gels with an apparent molecular weight of 48,000.     

Incorporation of label from [9, 10-methylene-14C] sterculic acid in rainbow trout,Salmo gairdneri

The distribution of radioactivity from sterculic acid, labeled on the 9,10-methylene carbon of the cyclopropene ring, was investigated in trout,Salmo gairdneri. Fifty percent of the administered dose was excreted in feces and urine by 168 hr, but less than 1% of the dose was expired as carbon dioxide during the same time period. Incorporation of radioactivity into most organs peaked at 119 hr, and the majority of the label in the liver was in the fatty acid portion of the lipid fraction. Total lipid radioactivity in liver was higher in trout conditioned to cyclopropene lipids, and a substantial amount of label was found in phosphatidylcholine and ethanolamine phospholipids as well as neutral lipid. The data demonstrate that rainbow trout readily absorb, transport and incorporate sterculic acid into tissue lipid, including membrane lipid, but cannot oxidize the methylene carbon of the cyclopropene ring to carbon dioxide. Technical Paper No. 4769, Oregon Agricultural Experiment Station, Oregon State University, Corvallis, Oregon 97331.     

Temperature-dependent deacylation of molecular species of phosphatidylcholine by microsomal phospholipase A2 of thermally acclimated rainbow trout,Salmo gairdneri 1

Using the ratios of kinetic parameters, V/Km, the deacylation of different molecular species of 1-palmitoyl,2-acyl phosphatidylcholine via microsomal phospholipase A₂ (PLA₂) was studied in liver tissue of thermally acclimated rainbow trout (Salmo gairdneri). In general, PLA₂ from fish acclimated to cold temperatures showed an order of preference for the acyl moieties of 18∶1>18∶1>18∶2>18∶0. Trout acclimated to warm temperatures generally preferred 18∶0 PC, but the actual order of preference depended on the temperature of the assays and the presence of endogenous lipids in the enzyme preparation. At 5 C, the particulate (microsomal) enzyme preferred 18∶0>18∶2>18∶1, but a lipid-free preparation of the enzyme preferred 18∶2>18∶0>18∶1. At 20 C, particulate enzyme preferred 18∶1>18∶0>18∶2 but purified enzyme preferred 18∶0>18∶2>18∶1. Thus, assay temperature and the presence of microsomal lipids had a greater effect on PLA₂ from fish acclimated to warm temperatures than fish acclimated to cold temperatures. The substrate preference of PLA₂ is discussed with reference to the previously observed changes in membrane fatty acid composition that occur with thermal acclimation in rainbow trout.     

Use of food treated with gamma radiation in the feeding of rainbow trout (Salmo gairdnerii irideus)

A rainbow trout diet, partially prepared with agroindustrial by-products, including laying hen's dung, was treated with gamma radiation (25 KGy). The objective was to reduce the microbiological contamination and test its effect on weight gain, feed efficiency and mortality of trouts. For this purpose, two groups of trouts were compared: one received irradiated food, and the other the same diet, but without treatment. The experience was carried out through a period of 32 weeks, during the free growth stage (from 2 to 20g). Microbiological contamination decreased from high values (greater than 6 X 10(6) germs/g of food) to acceptable levels (less than or equal to 3 X 10 germs/g of food), but the parameters measured in trouts, did not show any difference among both groups.     

Effects of a (n−3) polyunsaturated fatty acid-deficient diet on profiles of serum vitellogenin and lipoprotein in vitellogenic trout (Salmo gairdneri)

During the 6 months of vitellogenesis, 3-year-old female trout (Salmo gairdneri) were fed either an enriched (E) or an (n−3) polyunsaturated fatty acid (PUFA)-deficient (D) diet; serum vitellogenin (VG) and lipoproteins (d<1.21 g/ml) were analyzed at the third month of vitellogenesis (September) and at ovulation (December). The serum content of high density lipoproteins (HDL), the major protein class, maintained a mean value of 1500 mg/dl at both stages and with both diets. On the contrary, very low density lipoproteins (VLDL) were 90% higher during vitellogenesis than at spawning time, whereas excess vitellogenin circulated at this period (6580 mg/dl serum with diet E). The diet deficient in (n−3) lowered serum vitellogenin content by 16% in September and by 26% in December. The degree of (n−3) PUFA incorporation moderately decreased in low density lipoproteins (LDL) and in HDL with the (n−3)-deficient diet. The effect was more pronounced for 20∶5. On the other hand, essential 22∶6 was incorporated into vitellogenin at the same rate in September as in December with diet E (23% and 25%, respectively), whereas after a 3-month deficiency, the percentage fell to 12%; this percentage rose again to 19% at spawning time. These findings show that, although stored (n−3) PUFA were not exhausted after a 6-month dietary deficiency, the incorporation of essential fatty acids (EFA) into vitellogenin during the early stages of oogenesis was low, suggesting changes in egg composition that may influence hatching.     

Lipid composition of the pineal organ from rainbow trout (Oncorhynchus mykiss)

The lipid composition of the pineal organ from the rainbow trout (Oncorhynchus mykiss) was determined to establish whether the involvement of this organ in the control of circadian rhythms is reflected by specific adaptations of lipid composition. Lipid comprised 4.9% of the tissue wet weight and triacylglycerols were the major lipid class present (47% of total lipid). Phosphatidylcholine (PC) was the principal polar lipid, and smaller proportions of other phospholipids and cholesterol were also present. Plasmalogens contributed 11% of the ethanolamine glycerophospholipids (EGP). No cerebrosides were detected. The fatty acid composition of triacylglycerols was generally similar to that of total lipids in which saturated, monounsaturated and polyunsaturated fatty acids (PUFA) were present in almost equal proportions. Each of the polar lipid classes had a specific fatty acid composition. With the exception of phosphatidylinositol (PI), in which 20∶4n−6 comprised 27.4% of the total fatty acids, 22∶6n−3 was the principal PUFA in all lipid classes. The proportion of 20∶5n−3 never exceeded 6.0% of the fatty acids in any lipid class. The predominant molecular species of PC were 16∶0/22∶6n−3 and 16∶0/18∶1, which accounted for 33.2 and 28.5%, respectively, of the total molecular species of this phospholipid. Phosphatidylethanolamine (PE) contained the highest level of di-22∶6n−3 (13.0%) of any phospholipid. There was also 4.9% of this molecular species in phosphatidylserine (PS) and 4.1% in PC. In PE, the species 16∶0/22∶6, 18∶1/22∶6 and 18∶0/22∶6 totalled 45.1%, while in PS 18∶0/22∶6 accounted for 43.9% of the total molecular species. The most abundant molecular species of PI was 18∶0/20∶4n−6 (37.8%). The lipid composition of the pineal organ of trout, and particularly the molecular species composition of PI, is more similar to the composition of the retina than that of the brain. Molecular species are abbreviated as follows: e.g., 16∶0/22∶6 PC is 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine.     

Desaturation and chain elongation of essential fatty acids in isolated liver cells from rat and rainbow trout

Isolated hepatocytes from rainbow trout and rat were incubated with¹⁴C-labeled linoleic acid, linolenic acid, dihomogammalinolenic acid or eicosapentaenoic acid. The most striking difference in the desaturase activity was the lower level of Δ5 desaturase in trout than in rat. No Δ4 desaturation of 22∶4(n−6) to 22∶5(n−6) was observed in either of the two species, while the conversion of 22∶5(n−3) to 22∶6(n−3) was significant in both groups and highest in rainbow trout. The chain-elongating activity was remarkably similar in the two species, except for the “dead-end” elongation which was distinctly more important in fish.     

Significance of docosahexaenoic acid for rainbow trout (Oncorhynchus mykiss) larvae

N-3 fatty acids are essential for rainbow trout (Oncorhynchus mykiss). Our investigations specify the fatty acid requirements of rainbow trout larvae. One group of larvae was fed with Artemia ssp. rich in linolenic acid (18:3 n-3) and octadecatetraenoic acid (18:4 n-3), while the other group received a commercial fish feed containing high levels of long-chain polyunsaturated fatty acids (PUFA), mainly docosahexaenoic acid (22:6 n-3). After two and four weeks of feeding, the growth and fatty acid pattern of the larvae were determined. The fatty acid composition of the diet is reflected in the triglyceride composition of the fish, but there is no sign of conversion of 18:3 n-3 and 18:4 n-3 into long-chain polyunsaturated fatty acids. This is caused by limited chain elongation rather than by low enzyme activity of desaturase. In the triglycerides of the larvae, high levels of 18:4 n-3 were determined. This fatty acid was not transformed into the corresponding long-chain polyunsaturated fatty acids. Deficiency of 22:6 n-3 resulted in reduced larval growth. Therefore, it can be stated that docosahexaenoic acid is essential for rainbow trout larvae.     

Elongation and desaturation of dietary fatty acids in turbotScophthalmus maximus L., and rainbow trout,Salmo gairdnerii rich

Turbot and rainbow trout, which had previously recieved diets free of fat, were fed [1-14C] fatty acids. The distribution of radioactivity in the tissue fatty acids was examined 6 days later. In rainbow trout fed [1-14C] 18:3omega3, 70% of the radioactivity was present in 22:6omega3 fatty acid. In contrast, turbot fed [1-14C] 18:1omega9, 18:2omega6, or 18:3omega3 converted only small amounts of labeled fatty acids (3-15%) into fatty acids of longer chain length. The major product of the limited modification found in turbot was the dietary acid elongated by 2 carbon atoms.     

Isolation and characterization of proteolipids from rat liver (LSP) and kidney (KSP)

In this study, the biochemical characteristics of proteolipids of rat liver and kidney homogenates were compared. In all preparations, the proteo-lipids were eluted at the void volume of the Biogel A-15 m column after gel chromatography, and a molecular weight over 15×10⁶ was estimated. Electron microscopy of the concentrated void volume fractions showed globular particles with diameters of 30–100 nm for liver (LSP) and 30–60 nm for kidney (KSP) preparations that might be formed from plasma membrane fragments. After ultracentrifugation in a CsCl gradient, rat LSP and KSP floated in a small density range from 1.16–1.17 g/ml. There was no significant difference between the relative percentages of phospholipids, triglycerides and cholesterol of both proteo-lipids. However, the relative mean amount of total protein in rat KSP (60.4% vs 50.4%) was significantly higher and the content of free fatty acids (4.3% vs 12.6%) significantly lower compared to rat LSP. SDS-PAGE revealed at least 12 protein subunits ranging from 15,000–130,000 in both preparations, but one protein of about M_r 49,000 might represent a liver specific component. The isolated proteo-lipids from rat liver and kidney homogenates showed similar biochemical characteristics as those from human sources, which could explain the known cross-reactivity of antibodies against these preparations. The putative function of these proteo-lipids is not known, although there is some evidence from human studies that they carry receptor proteins.     

Lipid damage in farmed rainbow trout (Oncorhynchus mykiss) after slaughtering and chilled storage

The flow ice system including ozone (OFI condition) was tested for slaughtering and storage (up to 16 days) of farmed rainbow trout (Oncorhynchus mykiss). Lipid damage analyses were carried out and compared to sensory acceptance and instrumental colour changes. Comparison to individuals processed with the flow ice system in the absence of ozone (FI condition) was undertaken. Rainbow trout slaughtered and chilled under FI and OFI conditions showed a low lipid damage development, according to lipid oxidation and hydrolysis events and lipid composition (polyunsaturated fatty acids, phospholipids and endogenous antioxidants) changes. Additionally, both icing conditions led to largely good quality and shelf life times and to the absence of changes in colour properties. It is concluded that flow ice as such, or including the presence of ozone, can be considered as ideal strategy to be employed as slaughtering and storage system during the commercialisation of the actual farmed species. The ozone presence has shown some profitable effects as leading to an extended shelf life time by quality retention of several sensory parameters; in contrast, some negligible negative effects could be observed on the secondary and tertiary lipid oxidation development. However, the oxidation values reached by individuals kept under OFI conditions cannot be considered as particularly high.     

Isolation and identification of (3-methoxyphenyl)acetonitrile as a phytotoxin from meadowfoam (Limnanthes alba) seedmeal

Ethyl ether, ethanol, and water extracts of meadowfoam (Limnanthes alba Hartweg ex. Benth.) seedmeal were prepared and bioassayed against velvetleaf (Abutilon theophrasti Medicus) and wheat (Triticum aestivum L. Cardinal). Both the ethyl ether and ethanol fractions, but not the water extract, inhibited velvetleaf and wheat radicle elongation. Fractionation of the extracts indicated that (3-methoxyphenyl)acetonitrile (3-MPAN) was the active compound from both extracts, comprising >97% of the active ethanol fraction. 3-Methoxybenzyl isothiocyanate, which had been previously shown to be the major breakdown product of glucolimnanthin, the majorL. alba glucosinolate, was not detected in either extract. Radicle elongation of velvetleaf and wheat were inhibited by 3-MPAN with I₅₀ (the concentration required to inhibit growth by 50%) values of approximately 4 × 10^–4 M (velvetleaf) and 7×10^–4 M (wheat).Mention of firms or products does not imply endorsement by the U.S. Department of Agriculture over other firms or products not mentioned.     

Isolation and identification of constituents of Jasminum auriculatum (Vahl) leaves

Jasminum auriculatum (Vahl) (family: Malvaceae) widely grown in India was analysed for its fatty acids and waxy constituents. Straight-chain hydrocarbons (C₂₀-C₃₄), fatty acids (C₁₄-C₂₃) and fatty alcohols (C₂₁-C₃₂) were found in the 95% aqueous ethanol extract of the leaves of the plant. Malvalic acid was the only cyclic acid identified. Hydrocarbons (C₂₉ and C₃₁), fatty acids (C₁₆, C₁₈, C_18:1, C_18:2, C_18:3 and C₂₂) and fatty alcohols (iso-C₂₆, C₂₈ and C₃₀) were the major components. Four polyalcohols, namely D-mannitol, xylitol, inositol and sorbitol, have also been found in the alcoholic extract of the leaves.