Atsushi Nakagawa

Bio: Atsushi Nakagawa is an academic researcher from Hiroshima University. The author has contributed to research in topics: Liver function & Eicosapentaenoic acid. The author has an hindex of 4, co-authored 5 publications receiving 332 citations.

Effect of dietary vitamins C and E fortification on lipid metabolism in red sea bream Pagrus major and black sea bream Acanthopagrus schlegeli

Abstract: To determine the effect of vitamins C and E on lipid metabolism and interactions between them, L-ascorbyl-2-monophosphate-Mg (APM) and α-tocopherol acetate (TA) were fortified to a commercially based diet and fed to 0-year red sea bream Pagrus major and 1-year black sea bream Acanthopagrus schlegeli. Fortification of APM and TA, respectively, increased ascorbate (ASC) and α-tocopherol (α-Toc) contents in the organs. In addition, APM fortification increased α-Toc accumulation in both fishes, although TA fortification did not significantly affect the ASC content. Fortification of APM caused a depression in lipid accumulation in the intraperitoneal fat body and liver in red sea bream. Furthermore, a decrease in the serum thiobarbituric acid value in black sea bream and a reduction of the adipocyte diameter in the APM-fortified groups of both fishes were observed. However, fortification of TA did not affect these parameters as significantly as did fortification of APM. The shortest recovery time to air-dipping was found in the APM + TA-fortified group, followed by the APM-fortified group in red sea bream. The results implied an effect of vitamin C on lipid metabolism, and acceleration of vitamin E absorption and/or suppression of vitamin E degradation.

Effect of dietary ascorbate fortification on lipolysis activity of juvenile black sea bream Acanthopagrus schlegeli

Abstract: Hatchery-reared black sea bream Acanthopagrus schlegeli juveniles averaging 0.05 g in body weight were fed either a control diet (commercial diet) or an experimental diet in which the commercial diet was fortified with 50 mg l-ascorbyl 2-monophosphate Mg (APM)/100 g diet for 50 days. Calcium ascorbate supplemented as a vitamin mixture in the control diet was completely destroyed during storage. Fortification with APM significantly increased the ascorbic acid levels in the muscle, liver, brain and eye. Although APM fortification did not influence growth, survival or fish body composition, adipocyte diameter in the intraperitoneal fat body (IPF) was significantly reduced. After the feeding experiment, the fish were kept for 39 days without feeding. Fortification with APM resulted in high survival, high muscle protein retention and low body weight loss. The results suggested the necessity of fortification with an adequate amount of ascorbate in the diet. While fatty acid compositions of the IPF, muscle and liver were not significantly influenced by APM fortification, characteristic changes in the fatty acid profile were found after starvation. Vitamin C and highly unsaturated fatty acids seemed crossly interactive in relation to lipolysis activity in black sea bream juveniles.

Dietary effects of eicosapentaenoic acid and docosahexaenoic acid on lipid metabolism in black sea bream

Abstract: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were fortified at a level of 1.5% in a composed diet. The effects were confirmed in 0-year black sea bream Acanthopagrus schlegeli in terms of lipid metabolism and physiological activity. The EPA group was high in EPA in muscle, liver, intraperitoneal fat body (IPF), eye and brain. The levels of DHA in liver, eye, brain and heart were also high in the EPA group, suggesting that conversion of EPA to DHA occurred in those organs. Fortification of DHA increased the levels of DHA in organs except the eye, but did not affect EPA levels. Both the EPA and DHA groups showed smaller adipocytes or lower levels of lipid content than the control group. The starvation followed by feeding experiment caused marked body weight loss in the control group by consumption of muscle protein and lipids in IPF. Fortifications of EPA and DHA induced less mobilization of muscle protein and IPF lipids as energy. Liver function and resistance to air-dipping were improved by both EPA and DHA fortifications. The present results implied conversion of EPA to DHA in the fish with regard to parameters, such as lipid metabolism and physiological vitality.

Effect of dietary laurate on lipid accumulation and vitality in juvenile Pagrus major

Abstract: Based on the fact that medium-chain triglycerides suppress accumulation of reserved lipids in mammals and some fish species, the effect of dietary laurate on lipid accumulation and vitality was further examined in red sea bream. Ethyl laurate (0.5%) supplemented to the diet was fed to zero-year red sea bream (0.3 g) for 47 days. While dietary laurate did not influence growth performance, increasing of muscle ratio and decreasing of liver weight were observed. The dietary laurate led to reducing liver triglycerides, intraperitoneal fat body ratio, adipocyte diameter, and liver lipid. In addition, docosahexaenoic acid (DHA), functioning as a physiologically active nutrient, tended to increase in the muscle, liver, heart, brain and eyes. Dietary laurate activated resistance against air-dipping and liver function, as seen in the case of dietary DHA fortification. It is concluded that dietary laurate could depress lipid accumulation and improve vitality, while the influence of laurate on the tissue DHA deposition might relate to its efficacy.

The use of bacterial spore formers as probiotics

Abstract: The field of probiosis has emerged as a new science with applications in farming and aqaculture as alternatives to antibiotics as well as prophylactics in humans. Probiotics are being developed commercially for both human use, primarily as novel foods or dietary supplements, and in animal feeds for the prevention of gastrointestinal infections, with extensive use in the poultry and aquaculture industries. The impending ban of antibiotics in animal feed, the current concern over the spread of antibiotic resistance genes, the failure to identify new antibiotics and the inherent problems with developing new vaccines make a compelling case for developing alternative prophylactics. Among the large number of probiotic products in use today are bacterial spore formers, mostly of the genus Bacillus. Used primarily in their spore form, these products have been shown to prevent gastrointestinal disorders and the diversity of species used and their applications are astonishing. Understanding the nature of this probiotic effect is complicated, not only because of the complexities of understanding the microbial interactions that occur within the gastrointestinal tract (GIT), but also because Bacillus species are considered allochthonous microorganisms. This review summarizes the commercial applications of Bacillus probiotics. A case will be made that many Bacillus species should not be considered allochthonous microorganisms but, instead, ones that have a bimodal life cycle of growth and sporulation in the environment as well as within the GIT. Specific mechanisms for how Bacillus species can inhibit gastrointestinal infections will be covered, including immunomodulation and the synthesis of antimicrobials. Finally, the safety and licensing issues that affect the use of Bacillus species for commercial development will be summarized, together with evidence showing the growing need to evaluate the safety of individual Bacillus strains as well as species on a case by case by basis.