Mutsuo Hatano

Protein degradation and protease activity of chum salmon (Oncorhynchus keta) muscle during spawning migration

Sarcoplasmic protein content decreased significantly and myosin heavy chain was degraded gradually during spawning migration of chum salmon (Oncorhynchus keta).Acid and neutral proteinase activities increased significantly during spawning migration. These proteinase activities were higher in females than in males. High levels of acid proteinase were not caused by the injury of lysosomal membranes. Considering the physiological states of chum salmon, neutral proteinase activity might be related to the degradation of muscle protein.As the changes in serum sex steroids were similar to those in the protease activities during spawning migration, it was considered that high levels of protease activity during spawning migration were closely related to the serum levels of androgens.

Preparation of therapeutic phospholipids through porcine pancreatic phospholipase A2-mediated esterification and lipozyme-mediated acidolysis

Highly unsaturated fatty acid-containing phospholipids (HUFA-PL), which serve to increase the deformability of human red blood cells, were prepared through porcine phospholipase A2-mediated esterification of the lysophosphatidylcholine, which was derived from soy phosphatidylcholine (PC), and by Lipozyme-mediated acidolysis. Through these processes, phospholipase A2, with formamide as a water mimic, enhanced the incorporation of HUFA into positionsn-2 of PC and suppressed hydrolysis of the synthesized PL. On the other hand, Lipozyme-mediated acidolysis between positionsn-1 of soy PC and HUFA was enhanced by a combination of water and propylene glycol. Simultaneously, the recovered PL products showed decreased hydrolysis of newly synthesized health-beneficial HUFA-PL.

Sulfoquinovosyldiacylglycerol as an α-glucosidase inhibitor

Sulfoquinovosyldiacylglycerol isolated from an edible brown alga Hizikia fusiforme inhibited yeast α-glucosidase.

Metabolic pathways of carotenoids in chum salmon Oncorhynchus keta during spawning migration

1. Based on the contents and individual composition of carotenoids in the muscle, serum and ovaries of chum salmon during spawning migration, the reductive metabolism of astaxanthin to zeaxanthin was presumed to take place in the muscle of both male and female. 2. The metabolic rates of zeaxanthin and 4-keto-zeaxanthin in female serum were much faster than those in male serum.

Incorporation of n-3 polyunsaturated fatty acids into phospholipids of a marine bacterium Vibrio sp. cultivated with sardine oil

The fatty acid compositions of phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) were modified by cultivating the strain VB-5, a marine bacterium of genus Vibrio , with sardine oil triglyceride (TG). Icosapentaenoic and docosahexaenoic acids from sardine oil TG were clearly detected in both PE and PG of the strain VB-5.

Deterioration of chum salmon (Oncorhynchus keta) muscle during spawning migration—I. Changes in proximate composition of chum salmon muscle during spawning migration

Abstract 1. 1. The chemical compositions of chum salmon muscle during spawning migration were compared in terms of their physiological conditions. 2. 2. The gonadosomatic index (GSI) values were significantly elevated during the spawning migration stage, and high values were maintained during the upstream migration. The changes in GSI values were related to the hormone levels of testosterone and estradiol-17β. 3. 3. Muscle lipid content significantly decreased during the spawning migration stage, while a decrease in muscle protein was found during the upstream migration stage. Phospholipid content was constant during spawning migration. 4. 4. It was considered that lipid (triglyceride) and protein were utilized to mature the gonads and as an energy source to ascend the river, respectively.

Deterioration of chum salmon (Oncorhynchus keta) muscle during spawning migration—III. Changes in protein composition and protease activity of juvenile chum salmon muscle upon treatment with sex steroids

Abstract 1. 1. Changes in protein composition and protease activity of juvenile chum salmon muscle upon treatment with sex steroids were investigated. 2. 2. A slight breeding color was observed on chum salmon following the oral administration of 17α-methyltestosterone. Sarcoplasmic protein significantly decreased, while ninhydrin-positive substances from protein-free fractions significantly increased upon treatment with 17α-methyltestosterone. Autolytic activity of the fish treated with 17α-methyltestosterone drastically increased. 3. 3. Estradiol-17β did not significantly influence the protein composition and autolytic activity. 4. 4. These results indicate that androgen is closely related to the deterioration of chum salmon muscle.

Application of water mimics on preparation of eicosapentaenoic and docosahexaenoic acids containing glycerolipids

To obtain enhanced incorporation of highly unsaturated fatty acids and recovery of glycerolipid products, organic solvents with high dielectric constants (water mimics) were substituted for part of the essential water for lipase activation to study their effect on acidolysis and transesterification. In acidolysis/transesterification of fish oil triglycerides and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), Lipozyme IM-60 with ethylene glycol as a water mimic enhanced the incorporation of EPA and suppressed the hydrolysis of synthesized glycerolipid. On the other hand, transesterification between soy phosphatidylcholine and EPA was enhanced by a water and propylene glycol combination. In a nonaqueous medium that contained appropriate amounts of water and organic solvents (water mimics), Lipozyme IM-60 increased transesterification of EPA into soy phosphatidylcholine. Simultaneously, the recovered glycerolipid products showed decreased hydrolysis of newly synthesized EPA- and DHA-containing glycerolipids.

Comparison of carotenoids in muscle and ovary from four genera of salmonid fishes

1. 1. The cartenoids in muscles and ovaries of four genera of salmonids were examined from the comparative biochemical point of view. 2. 2. Astaxanthin was the main carotenoid in muscles and ovaries of genus Onchorhynchus and in muscle of steelhead. 3. 3. Idoxanthin, lutein, zeaxanthin and 4-keto-zeaxanthin besides astaxanthin were detected in the muscles and/or ovaries of brown trout, genus Salvelinus and Japanese huchen. 4. 4. These results demonstrated the marked genus and species specific differences in carotenoid features of muscles and ovaries from four genera of salmonids, suggesting the possibility of making use of reductive metabolites of astaxanthin such as idoxanthin, zeaxanthin, lutein and β-carotene tetrol as one of the chemical bases of systematics in salmonids.

Polyunsaturated fatty glyceride syntheses by microbial lipases

The degree of glyceride syntheses by lipase TOYO (Chromobacterium viscosum) and lipase OF (Candida cylindracea) using individual free fatty acids C18∶1, C18∶2, C18∶3, C18∶4, C20∶4, C20∶5 and C22∶6 were compared. Lipase TOYO incorporated each of the fatty acids into glycerol at levels of greater than 89%. Lipase OF incorporated most of the fatty acids at levels above 70% (docosahexaenoic acid incorporation was 63%). It was concluded that these two lipases are feasible for producing glycerides from unsaturated fatty acids.