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Two feeding experiments were conducted to examine the effects of feeding rate, fish size,and dietary protein and cellulose levels on the weight gain, feed conversion efficiency (FCE),protein efficiency ratio (PER), and feed consumption of Tilapia nilotica fingerlings. The effectsof factors were evaluated with 2 or 4 levels in a factorial design using an orthogonal array L8. InExperiment I, the weight gain (%) was slightly higher (P

The sterol composition of three species of marine invertebrates was investigated in the viewpoint of comparative biochemistry. The horseshoe crab, Trachypleus tridentus, containedcholesterol (78.0%) and small amounts of C27-, C28-, and C29-sterols with Δ^, Δ^, or Δ^-bond besides C26-Δ^-sterols. Cholesterol was also the major component in the sea caterpillar,Chloeia flava (75.3%) and the warf monkey, Ligia exotica (81.5%). The latter two invertebratespossessed C27, C28, and C29-sterols as a minor component besides cholesterol.

The composition of Δ^-sterols and other sterols of six bivalves collected in Okinawa, Japan,was investigated. Sterols were identified by gas-liquid chromatography (GLC) on 1.5% OV—17 and GLC-mass spectrometry. The bivalves examined contained seven Δ^-sterols and afew Δ^-sterols besides Δ^-sterols commonly occurring in marine molluscs. Saxostrea mordax andTridacna crocea contained cholesta-5,7-dienol as the major sterols (about 50% of totalΔ^-sterols), whereas Protostrea hyotis and Pinctada margaritifera possessed 24-methylcholesta-5,7,22-trienol at the levels of 65% and 53%, respectively. Atrina vexillum containedcholesta-5,7-dienol (40%), 24-methylcholesta-5,7,22-trienol (32%), and cholesta-5,7,22-trienol as the prominent sterols. Hippopus hippopus involved cholesta-5,7-dienol (14%),24-methylcholesta-5,7-dienol (12%), 24-methylcholesta-5,7,22-trienol (37%), and 24-ethylcholesta-5,7-dienol (37%). A possitive correlation was observed between the compositions ofsome Δ^-sterol (% of total Δ^-sterols) and corresponding Δ^-sterol (% of total Δ^-sterols).

The essential fatty acid requirements of Tilapia nilotica were examined by the 4-week feeding trialsusing the defined, artificial diets at water temperatures of 20°C and 28°C. The test diets contained1.0% levels of 18:1ω9, 18:2ω6, 18:3ω3, 20:4ω6, or ω3-HUFA (60% 20:5ω3 and 40% 22:6ω3)in addition to 4.0% 18:1ω9 as dietary lipids. The highest weight gains were observed on the dietssupplemented with 1.0% levels of 18:2ω6 or 20:4ω6. These indicated that T.nilotica requiresω6-fatty acids such as 18:2ω6 and 20:4ω6 rather than ω3-fatty acids in contrast to other fishes.However, the effects of water temperatures on the EFA requirements of T.nilotica were not clarified inthe present study due to the poor growth of this fish at 20°C.

Feeding trials using the prawn larvae Penaeus japonicus were conducted to examine the effectsof several dietary phospholipids (PL) on the growth, survival, and body lipid composition.The deficiency in dietary PL caused a total mortality within 6-7 days. When the prawn larvaewere fed carrageenan micro-bound diets with varying levels of supplemental soybean lecithin(SBL), the highest survival rates were obtained on diets with 3% SBL. Soybeanphosphatidylcholine (PC) and soybean phosphatidylinositol (PI) showed a higher nutritivevalue than bonito-egg PC and soybean phosphatidylethanolamine (PE) at a 3% supplementallevel. The deficiency in dietary PL resulted in a slight decrease in the concentrations of sterylesters, free sterols, PC, and PI in the bodies. The concentrations of PL such as PC seemedslightly higher in the prawn larvae receiving supplemental soybean PC than other supplementalPL such as soybean PI, soybean PE, and bonito-egg PC. However, the body lipidcompositions, on the whole, were not variable notably with the kinds of supplemental PLexamined. Also, the sum of 20:5ω3 and 22:6ω3 proportions of body PL was slightly higherin the prawn larvae receiving soybean PC rather than in those receiving other supplementalPL. The results of the present study offer additional evidence for the hypothesis that the PLrequirements of prawn larvae are related to the efficient transport of dietary lipids such ascholesterol.

Attempts to rear the larval crab, Portunus trituberculatus, with the aritificial microparticulate diets, nylon-protein microencapsulated diet (MED), gelatin-arabic gum-MED, cholesterol-lecithin micro-coated diet (MCD), and carrageenan microbinded diet (MBD), were conducted. In experiment I, the feeding rate of the rotifers in the practical seed production ofthe crab was reduced by half and replaced with one of the above artificial diets during theperiod of zoea2-zoea4 stages. The larval crabs receiving every artificial diet along with therotifers by the above mentioned manner had 11-20% survival comparable to the survival rateof the control group receiving the live feeds such as the rotifer, Artemia nauplii, and theminced meat of a short-necked clam. In experiment II, the larval crab was reared with oneof the artificial diets alone after hatching. Every artificial diet sustained growth of the larvalcrab from zoea1 to juvenile stages, although the survival rates of the crab receiving theartificial diets were lower than that of the crab receiving the live feeds (control group). Theresults of the present study thus show the success in rearing the larval crab with thearitificial microparticulate diets.

The biosynthesis of sterols in the red alga, Porphyridium cruentum, was investigated. The incubationof resting and growing cells with acetate-1-^{14}C gave the radioactive squalene and sterols. The resultsindicate that P.cruentum is capable of synthesizing sterols from acetate as well as in other plants. Thesterols isolated from the resting cells revealed radioactivity only in 22-dehydrocholesterol. In the caseof the sterols isolated from the growing cells, radioactivity was present at least in 22-dehydrocholesteroland cholesterol fractions. These results showed that P.cruentum synthesizes 22-dehydrocholesterol andcholesterol from acetate.

A species of yeast was isolated from the intestines of rainbow trout Oncorhynchus mykiss fed with pelleted diets in two different aquaculture stations.The yeast isolates were found to multiply by budding, not to form spore andany pigment and identified as Candida sp. The yeast isolates fermented glucose,galactose, sucrose, fructose, inulin and trehalose but not lactose, mannitol, maltose, inositol, melibiose, cellobiose and starch. The isolates grew poorly on Z-AIIagar without glucose, whereas they grew very well on Z-AII agar with glucose(ZAG agar). The representative strain Y91-01 grew in a temperature range of 13to 34°C, in a pH range of 2 to 9, and in a NaCl concentration range of 0 to 7%.Strain Y91-01 required biotin as incubated in glucose-(NH_4)_2SO_4 medium. Thetotal lipids extracted from strain Y91-01 cells contained C_16:1, C_16:0, C_18:1 andC_18:0 as major fatty acids.

The sterols of a dinoflagellate, Noctiluca milialis, was investigated. The specimens of N.milialis were collected from the sea water where a red water happened. Sterols were isolatedand then separated into six fractions by thin-layer chromatography on 10% AgNO_3-KieselgelG. The sterol components of six fractions were identified by a combined gas-chromatographyand mass spectrometry. N.milialis contained cholesta-5, 22E-dienol (4.8%), 5α-cholestanol(5.6%), 24-methylcholesta-5, 22E-dienol (72.5%), 24-methylenecholesterol (5.9%), andsmall amounts of other fifteen components. Interestingly, N.milialis contained 4α-monomethyl-sterols suchas 4α-methylcholestanol, 4α, 24-dimethylcholest-22-enol, 4α, 24-dimethylcholestanol,4α-methyl-24-ethylcholest-22-enol, and 4α-methyl-24-ethylcholestanol as minor components(

Feeding trials using purified diets were carried out to estimate the requirements of prawn, Penaeus japonicus, for essential fatty acids (EFA) such as linoleic acid (18: 2ω6), linolenic acid (18: 3ω3), eicosapentaenoic acid (20: 5ω3), and docosahexaenoic acid (22: 6ω3). For 18: 2ω6 and 18: 3ω3, the optimum weight gain was attained on diets containing 1.0% of either 18: 2ω6 or 18: 3ω3. However, the weight gain on diets containing 18: 2ω6 or 18: 3ω3 was inferior even at the optimum levels to that on the diets containing lower levels of 20: 5ω3 or 22: 6ω3.This indicated that 18: 2ω6 and 18: 3ω3 are not as effective EFA for the prawn as 20: 5ω3 and 22: 6ω3. For 20: 5ω3 and 22: 6ω3, the optimum weight gain was attained on the diets containing 1% of either 20: 5ω3 or 22: 6ω3.

The effects of dietary phospholipids on growth and survival of the larval red sea breamChrysophrys major and knife jaw Oplegnathus fasciatus were investigated using thepurified or formula diets. The inclusion of soybean lecithin (SBL) in the purified dietimproved growth and survival of the 10-day larvae of the red sea bream. The supplement ofdietary SBL to the formula diet also improved growth and survival of the 19-day larvae of theknife jaw. These results suggest that the inclusion of some phosholipids in diets may benecessary for good growth of the larval red sea bream and knife jaw as pointed out with thelarval Ayu Pleceglossus altivelis.

Feeding trials using purified diets, designed as 2-way layout experiments, wereconducted to examine the effects of dietary protein (casein), lipid (a 1 to 1 mixture ofsoybean oil and pollack liver oil), and digestible carbohydrate (dextrin) on the growth of Tilapia nilotica in terms of weight gain, feed conversion efficiency, and protein efficiency ratios. Tilapia fingerlings grew best on diets containing 40% protein, 12%lipid and 30% digestible carbohydrate. When the dietary lipid level was fixed at 10%,good growth was obtained with 30% protein + 40% digestible carbohydrate, 40%protein + 30% digestible carbohydrate, and 30% protein + 30% digestible carbohydrate. The optimum digestible energy for T.nilotica was around 380-410 kcal/100g diet. It also seems likely that T.nilotica utilizes lipids more effectively thandigestible carbohydrates as energy sources when receiving the 35% protein-diets whichmeet the protein requirement. These results indicate that T.nilotica fingerlings growoptimally on deits containing 30-40% protein, 12-15% lipids, and 30-40% digestiblecarbohydrate.

The sterols of the asteroids, Laiaster leachii and Coscinasterias acutispina, were examined by gas-liquidchromatography (GLC), column chromatography, and infrared absorption (IR), mass and nuclearmagnetic resonance (NMR) spectrometries.The sterol composition of two asteroids was fairly complex, however 7-cholestenol was predominant in these animals. Cholestanol, 7,22-cholestadienol, stellasterol and 7,24(28)-ergostadienol wereisolated from the asteroids as a pure sterol by column chromatography on a silver nitrate-impregnatedsilicic acid.Moreover, a small amount of sterol isolated from L.leachii was identified as (E)-24-ethylidene-cholest-7-en-3β-ol by IR, mass and NMR spectrometries and GLC.

This paper presents the variation in lipid compositions during the larval development of the prawn,Penaeus japonicus. The lipid concentrations were high in the ovaries, decreased to low levels atnauplius and zoea1 stages, and then remained roughly constant during the subsequent stages topost-larva1. The marked decrease in lipid concentrations during the period of ovaries to early zoealstages was mainly due to those in both phospholipids (PL) and triglycerides (TG) which were themajor lipid classes throughout the larval developmental stages. The free sterol concentrations didnot vary notably during the larval development from nauplius to post-larva1. As for total lipids, theproportions of highly unsaturated fatty acids such as 20:5ω3, 22:6ω3, and 20:4ω6 increased duringthe period of ovaries to zoea1 stage, whereas those of saturated and monoene fatty acids, specifically16:0 and 16:1, decreased during the same period. Moreover, the decrease in the proportions of 16:1and 18:1 during the above period was attributable mainly to those in both TG and PL, but theincrease in the proportion of 20:5ω3 and 22:6ω3 was due mainly to those in PL.

The biosynthesis of fatty acids from acetate-l-^C, linoleic acid-l-^C, and linolenic acid-l-^C was examined on Tilapia zillii. Also, the bioconversion of linoleic acid-l-^C to highlyunsaturated fatty acids (HUFA) was investigated on the puffer fish, Fugu rubripes. After injection of the radioactive precursors, the proportional radioactivity was measured on each fattyacid which was isolated by means of thin-layer chromatography on AgNO_3-Kieselgel G andpreparative gas-liquid chromatography.T.zillii was found to synthesize palmitic acid (16:0), palmitoleic acid (16:1), stearic acid(18:0), and oleic acid (18:1ω9) from acetate but not HUFA such as eicosapentaenoic acid(20:5ω3) and docosahexaenoic acid (22:6ω3). Also, T.zillii converted linolenic acid to 20:5ω3 and 22:6ω3, but the fish slightly metabolized linoleic acid to ω6 series of HUFA. Thepuffer fish converted linoleic acid to eicosadienoic acid (20:2ω6) and arachidonic acid (20:4ω6). These results were discussed in relation to the essential fatty acid requirements forT.zillii and the puffer fish.

The biosynthesis of fatty acids from acetate-1-^C was examined on the prawns,Penaeus monodon and Penaeus merguiensis. After injection of acetate-1-^C, polarlipids (PL) and neutral lipids (NL) were isolated from the whole body of theprawns, and the proportional radioactivity of individual fatty acids constituting PLand NL was investigated by using argentation thin-layer chromatography and preparative gas-liquid chromatography on 10% DEGS followed by radioactive measurements of the trapped samples.In both P.monodon and P.merguiensis, radioactivity was mainly associated withpalmitic acid (16: 0), palmitoleic acid (16: 1), stearic acid (18: 0), and oleic acid(18: 1ω9) but scarcely or slightly with linoleic acid (18: 2ω6), linolenic acid (18:3ω3), eicosapentaenoic acid (20: 5ω3), and docosahexaenoic acid (22: 6ω3). Theseresults suggest that 18: 2ω6, 18: 3ω3, 20: 5ω3, and 22: 6ω3 may be essential forP.monodon and P.merguiensis.

The sterol and fatty acid compositions of the lab-lab and snail (family Ceritheidae) wereanalyzed in the interests of bio-ecological transport of dietary sterols and fish nutrition in theextensive fishpond.The floating lab-lab contained cholesterol (40.2% of total sterols), 24-methycholesterol(14.0%), 24-methylcholesta-5, 22-dienol (17.3%), 24-ethylcholesterol (7.2%), and 24-ethylcholesta-5, 22-dienol (9.7%) as the major sterols. In the adhering lab-lab, 24-E-ethylidenecholesterol(13.3%) was the prominent sterol in addition to the above-mentionedfive sterols. The snail contained cholesterol (54.9%), cholest-7-enol (5.9%), 24-methylcholesterol(12.6%), 24-ethylcholesterol (3.9%), cholesta-5, 22-dienol (6.7%), 24-methylcholesta-5,22-dienol (9.4%), cholesta-5, 24-dienol (6.0%), and small amount of 24-norcholesta-5, 22-dienol(0.5%).The fatty acid composition of floating lab-lab resembled that of adhering lab-lab. The twotypes of lab-lab contained palmitic (16:0) and palmitoleic (16:1) acids as the major fatty acidsand substancial amounts of linoleic (18:2ω6, 3.6% and 6.1%) and linolenic (18:3ω3, 4.5%)acids. But, the lab-lab involved very low levels of eicosapentaenoic (20:3ω3) and docosahexaenoic(22:6ω3) acids.

This investigation deals with the separation of complex steryl acetate mixtures by an improvedprocedure for column chromatography on a silver nitrate-impregnated silicic acid. Separations wereeffected on the basis of the number and position of double bonds. Also, some relationship could beobserved between the chemical structure of steryl acetates and the mobility. The application of thistechnique for the sterol mixture isolated from a short-necked clam, Tapes philippinarum, gave the completeseparation of several components ; brassicasterol, 22-dehydrocholesterol, 22-trans-24-norcholesta-5, 22-dien-3β-ol, 28-isofucosterol, desmosterol, 24-methylenecholesterol, and an unknown sterol.

The present study is planned to examine the requirements of cholesterol for the prawn, Penaeusjaponicus, larvae in relation to the dietary levels of soybean phospholipids (PL). The experimentalgroups were designed as 2-way layout experiment (4x4 type): factor A, cholesterol content (%) indiets; factor B, soybean PL content (%) in diets. The zoea1 larvae of P.japonicus were reared with 16defined diets containing carrageenan as a binder for 7 days. The effects of cholesterol in improvinggrowth and survival of P.japonicus larvae seemed not to be affected by the dietary levels of soybeanPL. The optimum levels of cholesterol and soybean PL for P.japonicus larvae were estimated to be1.0% and 3.0%, respectively, when pollack liver oil was used as basal lipid sources.

The feeding trials were conducted to examine the effects of eicosapentaenoic acid methylester (EPA-ME),β-sitosterol, fucosterol, Tapes PL (phospholipids of a short-necked clam), soybean lecithin,and chicken-egg lecithin on cholesterol levels of the serum and liver in rats. EPA-ME, β-sitosterol,and fucosterol suppressed the elevation of cholesterol levels in both the serum and liver. However,the simultaneous addition of EPA-ME and either β-sitosterol or fucosterol did not increase thehypocholesterolemic effects on the serum and liver. Tapes PL, soybean lecithin, and chicken-egglecithin elevated the serum cholesterol level markedly. On the other hand, Tapes PL suppressed theincrease in liver-cholesterol levels in contrast with soybean lecithin and chicken-egg lecithin.

The effects of dietary phospholipids on growth of the larval Ayu Plecoglossus altiveliswere investigated by using the microparticulate diets with a carrageenan as a binder. The10-day larvae showed better growth on the diets with 3% levels of chicken-egg lecithin (CEL),soybean lecithin (SBL), or bonit-egg lecithin (BEL) than with a phospholipid-deficient diet.The nutritive value of SBL for the 10-day larvae was superior to that of bonito-egg cephalin.The growth and survival of 10-day larvae were improved with the increasing levels ofphospholipids from 0% to 5% when SBL was used as a phospholipid source. As for the 30-daylarvae, the addition of 3% phospholipids to the diets was also found to improve growth andsurvival, indicating the inferior nutritive value of soybean cephalin to those of CEL, SBL, andBEL. As for the 10-day and 30-day larvae, the nutritive values of CEL and BEL were slightlyhigher than that of SBL when 3% levels of respective phospolipids were added to the diets.

Feeding experiments were carried out by using a purified diet varying levels ofprotein (casein) on the fish, Tilapia zillii. Also, the effects of dietary energy levelson growth of T.zillii were examined.The optimum protein levels for T.zillii were determined to be 35-40% when caseinwas used as a sole protein source. The body weight gain increased in proportionto the dietary protein levels within the range of 0% to 35%. The utilization ofprotein by this fish was also evaluated with respect to protein efficiency ratio (P. E.R.), net protein ratio (N. P. R.), net protein utilization (N. P. U.), and feed efficiency. P. E. R., N. P. R. and N. P. U. decreased with the increase of casein levelsin the diets.The body weight gain of T.zillii was improved with the increase of calorie ofdiets, with suggestion that lipids are effective as energy sources more than carbohydrates.

In the present study, the effects of eicosapentaenoic acid (20: 5ω3) on growth andfatty acid composition of the prawn, Penaeus japonicus, were investigated and compared with those of linoleic (18: 2ω6), linolenic (18: 3ω3), and docosahexaenoic (22: 6ω3) acids. Six groups of the prawns were maintained on the diets containing lipidsas mentioned bellow: 1, 5% oleic acid (18: 1ω9) alone; 2, 4% 18: 1ω9+1% 18: 2ω6; 3, 4% 18: 1ω9+1% 18: 3ω3; 4, 4% 18: 1ω9+1% 20: 5ω3; 5, 4% 18: 1ω9+1%22: 6ω3; 6, lipid free.The highest weight gain and survival rate were attained in the group of prawnsfed the diet containing 4% 18: 1ω9+1% 20: 5ω3. The prawns receiving the dietswith 18: 2ω6 or 18: 3ω3 revealed lower weight gains and survival rates than thosereceiving 20: 5ω3 or 22: 6ω3. The supplementation of either 1% 20: 5ω3 or 22: 6ω3to the diet containing 4% 18: 1ω9 resulted in the increase of the proportion of ω3fatty acids such as 20: 5ω3 and 22: 6ω3 in the body of prawns. These data suggestthat 20: 5ω3 and/or 22: 6ω3 possess higher activity as essential fatty acids in theprawn, P.japonicus, than 18: 2ω6 and 18: 3ω3.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) methylesters (ME) were preparedfrom a squid-liver oil and their hypocholesterolemic activities examined with rats. The supplementof 0.3% EPA-ME to the diet containing 1.0% cholesterol and 4.0% butter as lipids reduced a serum-cholesterollevel markedly, whereas DHA-ME gave almost no effect on the serum-cholesterol level.Both EPA-ME and DHA-ME reduced the liver-cholesterol level as effectively as linoleic acid did.The supplement of small amounts of EPA-ME was also effective in lowering the serum-cholesterollevel; a dose of 0.03% EPA-ME suppressed by 60.7% the elevation of serum-cholesterol level.

The effects of dietary phospholipids on the growth, survival, and incidence of malformationwere investigated on the larvae of Ayu, Plecoglossus altivelis, with the purified diets. The inclusion of lecithin, soybean-lecithin (SB-lecithin) or chicken-egg lecithin (CE-lecithin) in thediets markedly improved the survival rate of the 10-day larvae, indicating that SE-lecithinwas more effective than CE-lecithin. Also, the incidence of malformation, especially scoliosisand twist of jaw, was reduced by the supplement of lecithin. Furthermore, the weight gain ofthe 100-day larvae was also improved by the supplement of 3% SB-lecithin or bonito-egglecithin to the diet containing 6% refined pollack liver oil-oleic acid (1:1, w/w). These resultssuggest that the addition of lecithin is indispensable for growth and survival of the larval Ayu.