Hisashi Murata

Hemolytic suppression roles of taurine in yellowtail Seriola quinqueradiata fed non‐fishmeal diet based on soybean protein

To elucidate the hemolytic suppression roles of taurine and the necessity of dietary taurine supplementation in yellowtail Seriola quinqueradiata fed a diet without fishmeal, juvenile fish with an initial body weight of 250 g were fed for 40 weeks in floating net cages on soybean protein diets supplemented with 0, 3.0, 4.5 and 6.0% taurine. Taurine concentration of the experimental diets were 0.03, 33.9, 52.8 and 71.6 mg/g, respectively. On the 21st week, fish fed the taurine unsupplemented diet had inferior growth and feed performances, higher death, and there were incidences of green liver and hemolytic anemia. In this group, hepatic and plasma taurine concentrations, serum osmolality and osmotic tolerance of erythrocytes (EC50 value) were significantly lower, and plasma hydroperoxide concentration was markedly higher than in the taurine supplemented groups. These conditions markedly improved corresponding with the increase of dietary taurine concentration. These results indicate that taurine plays a role in hemolytic suppression through osmoregulation and biomembrane stabilization in fish. In addition, it is suggested that yellowtail requires dietary taurine as an essential nutrition for maintaining physiological condition normally.

Efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in yearling red sea bream Pagrus major fed low-fishmeal diet

This study was performed to evaluate the efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in red sea bream Pagrus major fed a low-fishmeal (FM) diet. Yearling red sea bream were fed for 34 weeks on low-FM diets either supplemented with taurine, or without taurine, and the tissue taurine and bile pigment concentrations were measured. Compared to the fish fed the FM diet, fish fed the low-FM diet without taurine supplementation resulted in inferior feed performances and higher incidence of green liver related to the morphological transformation of the erythrocytes. In these fish, the hepatopancreatic taurine concentration was significantly lower and hepatopancreatic biliverdin concentration was high compared to the fish fed the FM diet. These parameters were markedly improved by taurine supplementation of the low-FM diet and were similar in levels to the fish fed the FM diet. These results indicate that green liver appearance and inferior feed performances of red sea bream fed the low-FM diet without taurine supplementation were caused by dietary taurine deficiency, and indicate the requirement of taurine supplementation to low-FM diets for red sea bream.

Severe oxidative stress is thought to be a principal cause of jaundice of yellowtail Seriola quinqueradiata

Abstract The jaundiced yellowtail Seriola quinqueradiata had yellow discolored skin and hyperbilirubinemia. Histology revealed that hemosiderin and ceroid occurred in the spleen. In the vascular system, there were vasculitis and sinusoidal dilatation. Hepatic cells showed degenerative figures with pyknotic or karyolytic nuclei, basophilic cytoplasm, cytoplasmic vacuoles in various sizes, and ceroidosis. In the bile duct system, however, there was no noticeable change. Hemoglobin contents of jaundiced fish were similar to those of control fish. Plasma taurine levels of jaundiced fish were significantly lower than those of control ( p 〈0.05). Judging from 2-thiobarbituric acid reactive substance values, in vivo lipid peroxidation progressed in the liver of jaundiced fish. In the plasma of jaundiced fish, contents of unconjugated bilirubin were significantly higher than those of conjugated bilirubin. A large amount of substance Xs, breakdown products of bilirubin scavenging active oxygen species, existed in the plasma of jaundiced fish. Therefore, jaundiced fish may suffer from severe oxidative stress, which might be a principal cause of jaundice. Liver superoxide dismutase and glutathione peroxidase activities of jaundiced yellowtail were significantly lower than those of controls.

Simultaneous determination of ascorbic acid and dehydroascorbic acid in fish tissues by high-performance liquid chromatography

An high-performance liquid chromatographic method with post-column derivatization has been developed for the simultaneous determination of ascorbic acid (AA) and dehydroascorbic acid (DHAA) in fish tissues. Extracted AA and DHAA were separated by a Shim-pack SCR-1O1H column within 20 min, reacted with sodium hydroxide containing sodium borohydride and monitored at 300 nm. The detection limits for both AA and DHAA were 0.1 microgram/ml.

High-performance liquid chromatographic analysis of ascorbyl-2-phosphate in fish tissues

L-Ascorbic-2-phosphate magnesium salt (APM) in fish tissues was determined by high-performance liquid chromatography. APM extracted with 5% metaphosphoric acid was separated by a LiChrospher 100 RP18 column within 20 min. The detection limit was 0.1 microgram/g tissue.

Relationship of the Judging Grades of Pork Carcasses to their Lipid Characteristics

本研究は,肉豚139頭の枝肉(格付「上」75頭,「中」47頭,「並」17頭)を用いて,格付等級と脂肪(背脂肪外層•内層,筋間脂肪および腎臓周囲脂肪)および骨格筋(胸最長筋:以下ロース芯と略記する)の脂質性状との関係を,脂質,脂肪酸,α-トコフェロール(α-Toc)およびコレステロール(Chol)の含量を通して調べた.各種脂肪組織のリノール酸(18:2)量は「並」>「上」>「中」の順で,背脂肪内層および腎臓周囲脂肪では格付等級相互間に有意差が存在した.他方,パルミチン酸(16:0)量と飽和脂肪酸/不飽和脂肪酸(SFA/USFA)比較の値は,「中」>「上」>「並」の順であった.さらに,「並」枝肉の背脂肪内層は脂質含量が低く,脂肪組織のしまりが劣っていることを示唆した.ロース芯の脂質含量は格付等級間の差異を示さなかったが,「中」は「上」および「並」枝肉に比較して16:0量とSFA/USFA比の値が有意に高く,18:2量が低かった.背脂肪の厚さと各種脂肪組織の18:2量との間並びにロース芯の脂質含量と18:2量との間には,有意な負の相関が存在した.α-Toc含量は,背脂肪内層およびロース芯において「並」>「上」>「中」であった.Chol含量は,背脂肪内層では「並」>「中」>「上」の順で「並」と「上」枝肉の間に有意差を示したが,ロース芯では格付等級間の差実がなかった.背脂肪内層では脂質含量とChol含量の間の有意な負の相関,まにロース芯では両者間の有意な正の相関が認められた.