Tadashi Sakai

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.

Relationship between delta‐aminolevulinic acid dehydratase genotypes and heme precursors in lead workers

BACKGROUND The objective of this study was to investigate the relationships between genotypes of delta-aminolevulinic acid (ALA) dehydratase (ALAD) and disturbances in the heme biosynthetic pathway by lead exposure. METHODS The subjects were 192 male lead workers and 125 control subjects. Blood lead concentrations (Pb-B), plasma ALA concentrations (ALA-P), and ALAD genotypes were determined for all subjects. In lead workers, ALAD activity, ALA in urine (ALA-U), and erythrocyte zinc protoporphyrin (ZP) were also determined. RESULTS The frequency of ALAD2 (minor type of ALAD allele) was calculated to be 0.087 in all subjects. No significant relationship was found between ALAD2 frequency and Pb-B levels in lead workers. ALAD1 homozygotes showed significantly higher levels of ZP and ALA-P in comparison with those of ALAD2 carriers at Pb-B levels more than 20 microg/dL and 40 microg/dL, respectively. CONCLUSIONS ALAD1 homozygotes might be more susceptible than ALAD2 carriers to disturbances in heme metabolism caused by lead exposure.

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.

Histological and histochemical changes in the gills of the yellowtail Seriola quinqueradiata exposed to the Raphidphycean flagellate Chattonella marina

The gills of the yellowtail Seriola quinqueradiata, exposed to Chattonella marina a red tide species, were examined histologically and histochemically. The pavement cells of primary lamellae were swollen in the exposed specimens. This presumably indicates that C. marina contains undetermined toxic substances. The number of mucous cells containing mucous decreased in proportion to the duration of exposure. The loss of the mucous substance in the cells is probably due to the ichthyotoxic stimulus caused by C. marina. A decrease of carbonic anhydrase activity in the secondary lamellae was confirmed, when mucous substances were lost in most mucous cells. Since the carbonic anhydrase usually exists in the epithelia of the secondary lamellae, it was presumably resolved by C. marina. The decrease of the carbonic anhydrase activity may cause certain physiological disadvantages to the fish exposed to C. marina.

High-performance liquid chromatographic determination of 1,3-diethyl-2-thiobarbituric acid--malonaldehyde adduct in fish meat.

The reaction conditions of 1,3-diethyl-2-thiobarbituric acid (DETBA)-malonaldehyde (MA) adduct formation were examined in order to analyze MA in fish tissue by high-performance liquid chromatography. A reaction mixture containing 4 mM butyl hydroxytoluene was heated at 100 degrees C for 150 min and the DETBA-MA adduct formed was separated by a Inertsil ODS column for 20 min. The detection limit was 5 pmol.

Decreases of natural killer cells and T-lymphocyte subpopulations and increases of B lymphocytes following a 5-day occupational exposure to mixed organic solvents.

Abstract The authors examined the effects of organic solvents on lymphocyte subpopulations in blood. Natural killer and T-lymphocyte subpopulations and B (CD19+) -lymphocytes were measured with flow cytometry in 16 male rotogravure printers on a Friday and on the following Monday. Numbers of all 3 subpopulations of natural killer cells (i.e., CD57+ CD16+, CD57-CD16+ and CD57+CD16- cells), 2 subpopulations of T lymphocytes (CD4+ CD45RA+ and total CD8+ cells) and total lymphocytes on Friday were significantly fewer than those found on the following Monday. Conversely, the number of B lymphocytes on Friday was significantly larger than the number on Monday. The number of B lymphocytes was significantly correlated with blood toluene levels on Friday. The alteration in the number of CD57+CD16+ NK cells from Friday to the following Monday was correlated inversely with the corresponding change in exposure level of toluene on Friday. The authors suggest that the effects of mixed organic solvents (primarily toluene) are recoverable decreases of natural killer cells and T lymphocytes and increases in B lymphocytes.

Sodium chloride as a preferred protein extractant for pork lean meat.

The protein extractability of sodium chloride (NaCl), potassium chloride (KCl) and lithium chloride (LiCl) under a range of molarity with in the physiological pH range (pH 6.0-8.0) was assessed to determine the best protein extractant for pork lean meat. The individual proteins in the extracts were identified by electrophoresis. The highest protein extractabilities at pH 7.0 for NaCl, KCl and LiCl were observed at 1.2, 1.1, and 1.1 M, respectively. There was no significant difference in protein extractability for KCl and LiCl within physiological pH range. NaCl had a significant increase of its protein extractability as pH increased from 6.0 to 6.5 followed by a relatively constant extractability. The NaCl had the highest protein extractability followed by LiCl and KCl. The maximum number of proteins (26 bands) was found at the optimum concentration of each salt. However, resolution and clarity of bands were better in NaCl extracts. The pH variation does not affect the number and the intensity of the bands.

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.

Effect of Bleeding on Hemoglobin Contents and Lipid Oxidation in the Skipjack Muscle

Skipjack samples were prepared using two different killing methods, namely, struggling death in iced sea water (control) and instant death by mechanical bleeding. The hemoglobin content in the bled muscles was significantly lower than that in the control. 4-Hydroxyhexenal content in the bled muscles was significantly lower than that in the control over 2 d of storage at 0 °C.

Effect of NaCl on the Lipid Peroxidation-Derived Aldehyde, 4-Hydroxy-2-nonenal, Formation in Boiled Pork

Pork was boiled at 100 °C for 5, 10 and 15 min and stored at 0 °C, and changes in the 4-hydroxynonenal (HNE), malonaldehyde (MA) and fatty acid (FA) contents were analyzed immediately and 3 days later. The HNE, MA and FA contents in all samples were not significantly different from each other. Pork samples containing none (control), 1% and 2% NaCl were boiled at 100 °C for 5 min and stored at 0 °C, and changes in the HNE, MA and FA contents and cooking yields were immediately analyzed and after 0, 1, 2 and 3 days. Cooking losses in the NaCl-containing samples were significantly lower than those of the control. The HNE contents in the control samples of boiled pork had significantly increased after 3 days of storage, while the contents in the NaCl-containing samples were significantly lower than those of the control after 1, 2 and 3 days of storage. The MA contents in all samples were not significantly different from each other. All FA contents analyzed had decreased in all samples after 3 days of storage. The decrease ratio of highly unsaturated fatty acids was lowest in the sample containing 2% NaCl.