Publications by authors named "Shinobu Fujimura"

22 Publications

  • Page 1 of 1

Reduction in dietary lysine increases muscle free amino acids through changes in protein metabolism in chickens.

Poult Sci 2020 Jun 8;99(6):3102-3110. Epub 2020 May 8.

Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan; Center for Transdisciplinary Research, Niigata University, Niigata 950-2181, Japan. Electronic address:

Taste is crucial to meat quality, and free Glu is an important taste-active component in meat. Our recent study showed that the short-term feeding of a low-Lys diet increases the concentration of free Glu and other free amino acids in chicken muscle and improves its taste. Here, we investigated the mechanisms by which the feeding of a low-Lys diet increases free Glu in chicken muscle. Two groups (n = 10 per group) of 28-day-old female Ross strain broiler chickens were fed diets with a graded Lys content of 90% or 100% of the recommended Lys requirement (according to National Research Council [1994] guidelines) for 10 D. Free amino acid concentrations and the mRNA abundance of protein metabolism-related genes were measured in breast muscle, and breast muscle metabolome analysis was conducted. Free Glu in muscle was increased by 51.8% in the Lys 90% group compared with the Lys 100% group (P < 0.01). Free threonine, glutamine, glycine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, and 3-methyl-histidine concentrations in breast muscle were also increased in the Lys 90% group (P < 0.05). Metabolome analysis also showed that free amino acids were increased in the Lys 90% group. The mRNA abundance of μ-calpain, caspase-3, and 20S proteasome C2 subunit were increased in the Lys 90% group (P < 0.05). Moreover, the free Glu concentration in muscle was correlated with mRNA abundance of μ-calpain (r = 0.74, P < 0.01), caspase 3 (r = 0.69, P < 0.01), 20S proteasome C2 subunit (r = 0.65, P < 0.01), and cathepsin B (r = 0.52, P < 0.05). Our study suggests that the feeding of a low-Lys diet to chickens increased the free Glu content of breast muscle by promoting protein degradation.
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http://dx.doi.org/10.1016/j.psj.2019.11.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7597547PMC
June 2020

Descriptive Sensory Traits of Cooked Eggs Laid from Hens Fed Rice Grain.

J Poult Sci 2019 Jul;56(3):231-235

Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, Tsukuba 305-0901, Japan.

Descriptive sensory characteristics of eggs produced by conventional corn-based feeding and unhulled whole rice grain-feeding were compared in two cooking procedures using a trained panel. Rice-feeding significantly decreased brothy and roasted odor in eggs cooked into half-cooked egg yolks, and decreased the creamy odor, smoothness and moisture of eggs cooked into custard puddings. However, a statistical interaction between rice-feeding and production farm was not observed in every sensory attribute. These findings indicated that replacing corn with unhulled whole rice grain in diets for laying hens alters the sensory attributes of eggs.
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http://dx.doi.org/10.2141/jpsa.0180082DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005385PMC
July 2019

Dietary Supplementation with Lysine and Threonine Modulates the Performance and Plasma Metabolites of Broiler Chicken.

J Poult Sci 2019 Jul;56(3):204-211

Department of Biological Production, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.

Here, we investigated whether the optimal threonine (Thr) to lysine (Lys) ratio in high Lys diet improves the growth performance of modern broiler chickens at finisher period and determined the possible mechanism underlying improvement in the growth performance of chickens fed with high Lys or Lys + Thr diet using metabolome analyses. Eighteen 21-day-old chickens housed in individual cages were randomly divided into three groups of six chickens fed with different diets as follows: control diet, high Lys diet (150% Lys content of National Research Council requirement), and high Lys + Thr diet (0.68 of Thr/Lys in high Lys diet). Body weight gain (BWG) increased in chickens receiving high Lys diet as compared with those fed with the control diet (<0.05); no significant difference was observed in BWG of chickens from high Lys + Thr and high Lys groups. Feed conversion ratio (FCR) was lower in chickens fed with high Lys or high Lys + Thr diet than in those on the control diet. Serotonin concentration increased in the plasma of chickens fed with high Lys diet as compared to those fed with other diets. A negative correlation was observed between plasma serotonin concentration and FCR. These results provide the first evidence on the use of high Lys in broiler diets to reduce FCR during finisher period, which may be associated with change in plasma serotonin concentration. These findings suggest that high Lys content in finisher diet, but not high Thr + Lys diet, may affect the peripheral serotonergic metabolism and improve FCR. Thus, plasma serotonin may serve as a biomarker of FCR in broilers.
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http://dx.doi.org/10.2141/jpsa.0180104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005390PMC
July 2019

Evaluation of Postprandial Glycemic Response and Physical Properties of High-Amylose Rice "Koshinokaori".

J Nutr Sci Vitaminol (Tokyo) 2019 ;65(Supplement):S117-S121

Faculty of Agriculture, Niigata University.

This study evaluated the postprandial glycemic response and physical properties of the high-amylose rice, Koshinokaori (KK), cooked under different conditions. Twelve healthy subjects (Japanese, 6 males, 6 females) were given cooked, white KK rice or tomato chicken rice (TCR) using KK rice. The Japanese standard rice, Koshihikari (KH), was used as reference. All meals contained the same amount (50 g) of available carbohydrate. Blood glucose levels were measured at 0 (fasting), 15, 30, 45, 60, 90, and 120 min after each meal. The results from the cooked, white KK rice showed a significant difference in blood glucose variation at 60, 90, and 120 min and the incremental area under the curve (IAUC) of blood glucose concentration for KK cooked at optimal water to rice ratio was observed. Blood glucose variation and IAUC after intake of TCR-KK rice was lower than that after TCR-KH rice intake. Addition of 5% trehalose to KK rice resulted in a smaller decrease in adhesiveness and stickiness of cooked rice after 180 min at 20ºC. The addition of 5% trehalose to KK rice also produced favorable results in the sensory evaluation. KK rice produces favourable postprandial glycemic responses and physical properties under varied cooking condition and thus, may be beneficial in the prevention of lifestyle-related diseases such as type 2 diabetes.
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http://dx.doi.org/10.3177/jnsv.65.S117DOI Listing
March 2020

Influence of Varying Dietary Protein Levels on Glycation of Albumin, Tryptophan and Valine in the Plasma of Chickens.

J Poult Sci 2017 Jul;54(3):242-246

Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan.

Glycation is a chemical reaction in which reducing sugars bind non-enzymatically to compounds containing amino groups. Avian species like chickens are hyperglycemic animals and have high body temperature compared to mammalian species, which enables avian species to accelerate the glycation of proteins and amino acids with glucose. Although varying dietary crude protein (CP) levels alter plasma concentrations of proteins and amino acids, the influence of varying CP levels on the glycation of plasma proteins and amino acids has not been studied so far. In the present study, therefore, glycation of albumin, tryptophan and valine in the plasma of chickens fed diets with varying CP levels (0, 10, 20, 40 and 60%) was examined. At the end of the experimental period, blood samples were collected and plasma concentrations of glycoalbumin, glycated tryptophan (tryptophan-Amadori product and (1R, 3S) - 1 - (D - gluco - 1, 2, 3, 4, 5 - pentahydroxypentyl) - 1, 2, 3, 4 - tetrahydro - - carboline - 3 - carboxylic acid (PHP-THC)), and valine-Amadori product were measured. Although plasma albumin concentration was reduced along with the decrease in dietary CP levels from 20% to 0%, glycoalbumin in the plasma was increased under such dietary conditions. Similar increase in the ratios of tryptophan-Amadori product to tryptophan and valine-Amadori product to valine in the plasma of chickens fed a protein-free diet was observed. These results suggest that dietary protein deficiency might enhance the non-enzymatic glycation of plasma proteins and amino acids in chickens.
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http://dx.doi.org/10.2141/jpsa.0160146DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477214PMC
July 2017

Rice endosperm protein slows progression of fatty liver and diabetic nephropathy in Zucker diabetic fatty rats.

Br J Nutr 2016 Oct 11;116(8):1326-1335. Epub 2016 Oct 11.

1Center for Transdisciplinary Research,Niigata University,8050,Ikarashi 2-no-cho,Nishi-ku,Niigata 950-2181,Japan.

We previously reported that rice endosperm protein (REP) has renoprotective effects in Goto-Kakizaki rats, a non-obese diabetic model. However, whether these effects occur in obese diabetes remains unclear. This study aimed to clarify the effects of REP on obese diabetes, especially on fatty liver and diabetic nephropathy, using the obese diabetic model Zucker diabetic fatty (ZDF) rats. In total, 7-week-old male ZDF rats were fed diets containing 20 % REP or casein (C) for 8 weeks. Changes in fasting blood glucose levels and urinary markers were monitored during the experimental period. Hepatic lipids and metabolites were measured and renal glomeruli were observed morphologically. HbA1c levels were significantly lower in rats fed REP, compared with C (P<0·05). Compared with C in the liver, REP prevented lipid accumulation (total lipid, TAG and total cholesterol, P<0·01). Liver metabolome analysis indicated that levels of metabolites associated with glycolysis, the pentose phosphate pathway and carnitine metabolism were significantly greater in the REP group than in the C group (P<0·05), suggesting activation of both glucose catabolism and fatty acid oxidation. The metabolite increases promoted by REP may contribute to suppression of liver lipid accumulation. Urinary excretion of albumin and N-acetyl-β-d-glucosaminidase was significantly reduced in rats fed REP for 8 weeks (P<0·01). In addition, there was a distinct suppression of mesangial matrix expansion and glomerular hypertrophy in response to REP (P<0·01). Thus, REP had preventive effects on obese diabetes, fatty liver and diabetic nephropathy.
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http://dx.doi.org/10.1017/S0007114516003512DOI Listing
October 2016

Protective effect of composite earthworm powder against diabetic complications via increased fibrinolytic function and improvement of lipid metabolism in ZDF rats.

Biosci Biotechnol Biochem 2016 Oct 9;80(10):1980-9. Epub 2016 Jun 9.

b Graduate School of Science and Technology , Niigata , Japan.

Thrombosis is the leading cause of mortality globally. It is not only a complication but also a risk factor for progression of diabetes. However, alternative oral therapies and prophylaxis with less adverse effect for thrombosis have not been well studied. In this study, composite powder containing earthworm (CEP) was used and its fibrinolytic activity was measured. CEP was found to have a high urokinase-type plasminogen activator like activity in an in vitro assay. It also had significantly shortened euglobulin clot lysis time (ECLT) at 4 and 24 h after ingestion in Sprague Dawley rats. Zucker Diabetic Fatty rats were used to assess the effect of CEP on diabetes and diabetic nephropathy. After 10 weeks of feeding, CEP significantly shortened ECLT and attenuated HbA1c, hepatic lipid accumulation, and urinary albumin excretion and improved glomerular mesangial matrix score. Therefore, CEP may have beneficial effects on diabetes and diabetic nephropathy.
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http://dx.doi.org/10.1080/09168451.2016.1166932DOI Listing
October 2016

Reduction of dietary lysine increases free glutamate content in chicken meat and improves its taste.

Anim Sci J 2017 Feb 15;88(2):300-305. Epub 2016 May 15.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

Taste is a crucial factor of meat quality, and amino acids are important taste-active components in meat. Here, the effects of dietary lysine (Lys) content on taste-active components in meat, especially free glutamate (Glu), were investigated. Twenty-eight-day-old broilers (Gallus gallus) were fed diets with graded Lys content of 90% or 100% of the recommended Lys requirement, (according to the National Research Council, ) for 10 days. Free amino acid content in meat and sensory scores of meat soup were estimated. Free Glu content, the main taste-active component of meat, was significantly increased by a reduction of dietary Lys. Compared with the Lys 100% group (control), free Glu concentrations of meat were increased by 35.7% in the Lys 90% group (P < 0.05). In addition, free glycine, valine, isoleucine, leucine, histidine and threonine concentrations of meat were significantly increased in the Lys 90% group (P < 0.05). Sensory evaluation of meat soup made from the Lys 100% and 90% groups indicated different meat tastes. Sensory scores of taste intensity, umami and kokumi tastes were significantly higher in the Lys 90% group. These results suggest that a reduction of dietary lysine increased free glutamate content in meat and improved its taste.
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http://dx.doi.org/10.1111/asj.12577DOI Listing
February 2017

Effect of dietary histidine on contents of carnosine and anserine in muscles of broilers.

Anim Sci J 2015 May 17;86(5):541-6. Epub 2014 Dec 17.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

Carnosine (β-alanyl-L-histidine) and anserine (β-alanyl-1-methyl-L-histidine) are dipeptides mainly found in skeletal muscle and brain of many vertebrates, and particularly high concentrations are observed in chicken pectoral muscles. It was reported that these peptides have many functions, such as antioxidant activity. In this study, we examined the effect of different levels of dietary histidine on carnosine and anserine contents in broiler muscles. The 14-days-old female Chunky strain broilers were given feeds containing three different levels of histidine; 67% (Low-His), 100% (Control) and 200% (High-His) of histidine requirement according to the NRC (1994). Chicks were fed experimental diets for 10 days. Both dipeptides in muscle were significantly decreased. In particular, carnosine was not detected at all in the Low-His group and was significantly increased in the High-His group. Both dipeptides were not detected in plasma. These results indicated the possibility to produce chicken meat with enhanced amount of these dipeptides by high histidine feeding.
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http://dx.doi.org/10.1111/asj.12322DOI Listing
May 2015

Regulation of free glutamate content in meat by dietary lysine in broilers.

Anim Sci J 2015 Apr 9;86(4):435-42. Epub 2014 Dec 9.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

Regulation of taste is important for improving meat quality and glutamate (Glu) is one of the important taste-active components in meat. Here, the effects of dietary lysine (Lys) content on taste-active components in meat, especially free Glu, were investigated. Fourteen-day-old broiler chicks (Gallus gallus) were fed on diets containing 100% or 150% of the recommended Lys content for 10 days. Concentrations of free amino acids in plasma, muscle and liver were measured. The levels of messenger RNAs (mRNAs) for enzymes related to Glu metabolism were determined in muscle and liver. The concentration of muscle metabolites was also determined. The free Glu content in muscle of chicks fed the Lys150% diet was increased by 44.0% compared with that in chicks fed the Lys100% diet (P < 0.01). The mRNA level of lysine α-ketoglutarate reductase, which is involved in Lys degradation and Glu production, was significantly increased (P < 0.05) in the Lys150% group. Metabolome analysis showed that the Lys degradation products, muscular saccharopine, pipecolic acid and α-aminoadipic acid, were increased in the Lys150% group. Our results suggest that free Glu content in muscle is regulated by Lys degradation. These results suggest that a short-term feeding of high-Lys diet could improve the taste of meat.
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http://dx.doi.org/10.1111/asj.12321DOI Listing
April 2015

In vivo digestibility of rice prolamin/protein body-I particle is decreased by cooking.

J Nutr Sci Vitaminol (Tokyo) 2014 ;60(4):300-4

Center for Transdisciplinary Research, Niigata University.

Rice has storage proteins, e.g., glutelin, globulin and prolamin, in the seeds, which are used as nitrogen sources during germination. Rice prolamin has been reported to be an indigestible protein that decreases the nutritional value of rice. However, the causes for the indigestibility of prolamin are currently not clear. The objective of this study was to determine if prolamin is naturally indigestible or if cooking affects its digestibility. The gastrointestinal (GI) transit of rice 23 kDa glutelin (23G) and 13 kDa prolamin (13P) in Wistar/ST rats fed raw rice (RR) and cooked rice (CR) diets was assessed using Western blot analysis. We also measured the excretion of these proteins in the feces of these rats. Additionally, morphological observation of the structure of type-I protein bodies in the feces was performed using electron microscopy. Assessment of GI transit revealed that 23G rapidly disappeared from the GI contents of both the RR and CR groups, but 13P accumulated in the cecum of the CR group. In the CR group, prolamin, maintaining the structure of PB-I, was fully excreted in the feces. These results indicate that rice prolamin is not indigestible by nature, but is rendered indigestible by cooking.
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http://dx.doi.org/10.3177/jnsv.60.300DOI Listing
June 2015

Effect of dietary astaxanthin rich yeast, Phaffia rhodozyma, on meat quality of broiler chickens.

Anim Sci J 2014 Oct 19;85(10):895-903. Epub 2014 May 19.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

We evaluated effects of dietary supplementation with astaxanthin (Ax)-rich yeast, Phaffia rhodozyma (Xanthophyllomyces dendrorhous), on broiler chicken meat quality. Fourteen-day-old female Ross broilers were divided into three groups: control group, Ax-free diet; Ax 10 group, 10 mg/kg Ax diet; and Ax 20 group, 20 mg/kg Ax diet for 28 days. At 42 days old, chickens were slaughtered, and then growth performance, meat quality and sensory attributes were analyzed. Compared with the control, a* values increased significantly after slaughter and 48 h postmortem for Ax 20 samples (P<0.05) and for b* values in Ax 20 and Ax 10 groups (P<0.05). Cooking loss decreased in the Ax 20 group (P<0.05). After 120 h aging, contents of several free amino acids and total free amino acid content of Ax 20 group were significantly higher than the control (P<0.05). In sensory evaluation, meat texture attributes improved significantly in the Ax 20 group (P<0.01). No significant changes occurred in flavor attribute scores of meat soup from the Ax 20 group compared with the control even though most assessors preferred meat soup from the Ax 20 group. Overall, Ax-rich yeast in the diet improves broiler chicken meat quality.
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http://dx.doi.org/10.1111/asj.12221DOI Listing
October 2014

Diversity of amino acid signaling pathways on autophagy regulation: a novel pathway for arginine.

Biochem Biophys Res Commun 2014 Mar 31;446(1):8-14. Epub 2014 Jan 31.

Department of Applied Biological Chemistry, Faculty of Agriculture, Graduate School of Science and Technology, Japan; Center for Transdisciplinary Research, Niigata University, 2-8050 Ikarashi, Nishi-Ku, Niigata 950-2181, Japan. Electronic address:

Autophagy is the intracellular bulk degradation process to eliminate damaged cellular machinery and to recycle building blocks, and is crucial for cell survival and cell death. Amino acids modulate autophagy in response to nutrient starvation and oxidative stress. We investigated the relevance of reactive oxygen species (ROS) production on the regulation of autophagy using amino acids, both as a mixture and individually, in rat hepatoma H4-II-E cells. Nutrient starvation elevated ROS production and stimulated autophagy. Treatment with complete (CAA), regulatory (RegAA) and non-regulatory (NonRegAA) amino acid mixtures showed significant suppression of ROS production, whereas only CAA and RegAA exhibited significant suppression of autophagy, suggesting a dissociation of the two responses. The effects of individual amino acids were examined. Leucine from RegAA decreased ROS production and suppressed autophagy. However, methionine and proline from RegAA and arginine, cystine and glutamic acid from NonRegAA suppressed autophagy with an opposite increase in ROS production. Other amino acids from the NonRegAA group showed stimulating effects on ROS production without an autophagic response. Arginine's effect on autophagy suppression was not blocked by rapamycin, indicating an mTOR-independent pathway. Inhibitor studies on arginine-regulated autophagy may indicate the involvement of NO pathway, which is independent from ROS and mTOR pathways.
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http://dx.doi.org/10.1016/j.bbrc.2014.01.117DOI Listing
March 2014

Effect of dietary vitamin E on broiler meat qualities, color, water-holding capacity and shear force value, under heat stress conditions.

Anim Sci J 2013 Nov 22;84(11):732-6. Epub 2013 Aug 22.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

This study was conducted to evaluate the effect of dietary vitamin E (VE) on broiler meat quality, especially focused on PSE (pale color, soft and exudative), under chronic heat stress (HS) conditions. Twenty-eight-day-old female Ross broilers were kept in independent cages with a controlled temperature of 24°C (normal temperature: NT) or 30°C (high temperature: HT). The NT chickens were fed basal feed. The HT chickens were fed basal feed (HT) or VE (200 mg/kg) added feed (HT + E). Broilers were weighed and slaughtered at 38 days old. The breast muscle was removed immediately and then the samples were used for determination of meat color, pH, water holding capacity (WHC) and shear force value (SFV). Body weight gain and feed intake were significantly decreased in the HT and HT + E groups compared to the NT group. VE supplementation did not affect the growth performance. Chronic HS at 30°C for 10 days may cause deterioration of meat quality such as PSE. The effects of chronic HS on meat quality were most significant in the toughness of broiler breast meat. Supplementation of VE in broiler feed would be effective to prevent the extent of PSE on broiler meat by chronic HS.
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http://dx.doi.org/10.1111/asj.12079DOI Listing
November 2013

Rice protein ameliorates the progression of diabetic nephropathy in Goto-Kakizaki rats with high-sucrose feeding.

Br J Nutr 2013 Oct 28;110(7):1211-9. Epub 2013 Mar 28.

Center for Transdisciplinary Research, Niigata University, Niigata 950-2181, Japan.

The effect of rice protein (RP) on diabetic nephropathy in non-obese, spontaneous type 2 diabetic Goto-Kakizaki (GK) rats was investigated.GK rats at 7 weeks of age were fed 20% RP or casein (C) in standard or high-sucrose diets for 10 weeks. Plasma total cholesterol,TAG, alkaline phosphatase (ALP), adiponectin, creatinine and urinary albumin excretion (UAE) were measured and renal histology was evaluated. Compared with C, RP lowered plasma TAG and improved plasma adiponectin levels in GK rats fed the standard diet (P<0·05), and also lowered total cholesterol and ALP in high-sucrose-fed GK rats (P<0·05). RP markedly suppressed the sharp increase in UAE when GK rats were fed high-sucrose diets (P<0·05), and prevented glomerular mesangial matrix expansion in the deep renal cortex near the corticomedullary junction (P<0·05). These results strongly indicate that dietary RP can ameliorate the progression of diabetic nephropathy at an early stage compared with C.
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http://dx.doi.org/10.1017/S0007114513000354DOI Listing
October 2013

Regulation of muscular glutamate metabolism by high-protein diet in broiler chicks.

Anim Sci J 2011 Feb 13;82(1):86-92. Epub 2010 Oct 13.

Graduate School of Science and Technology, Niigata University, Niigata, Japan.

The major taste active component, glutamate (Glu), improves the taste of meat. In this study, we investigated the effect of a short-term high-protein (HCP) diet on the intramuscular free Glu content to improve the taste of meat. Furthermore, we elucidated how the muscle free Glu content was controlled by the HCP diet. Chicks (14 days old) were fed the control diet or HCP diet for 10 days. Plasma and muscle free amino acid concentrations, and activity and messenger RNA (mRNA) expression of muscle enzymes related to Glu metabolism were determined. Muscle free Glu content was increased (P < 0.01) by 51%. Activity and mRNA expression of glutaminase (GA), which is one of the major Glu-related enzymes, were significantly decreased (P < 0.05) in the HCP group because of feedback inhibition. The mRNA expression of lysine α-ketoglutarate reductase (LKR), which is the enzyme involved in lysine (Lys) degradation and Glu production, was significantly increased (P < 0.001) in the HCP group. These results suggest that short-term dietary HCP feeding is an effective treatment for improving the taste of meat. Furthermore, our results suggest that the free Glu content in muscle is regulated by GA and LKR.
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http://dx.doi.org/10.1111/j.1740-0929.2010.00811.xDOI Listing
February 2011

Beef texture characterization using internationally established texture vocabularies in ISO5492:1992: differences among four different end-point temperatures in three muscles of Holstein steers.

Meat Sci 2010 Oct 24;86(2):422-9. Epub 2010 May 24.

National Institute of Livestock and Grassland Science, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan.

'Tenderness' has been an important sensory characteristic for beef, although 'tenderness' has not been commonly defined. On the other hand, ISO5492:1992 provides internationally established vocabularies for sensory analysis with simple definition. The aim of this study was texture characterization for three beef muscles cooked to four end-point temperatures using ISO5492:1992 texture terms in Japanese to develop objective sensory evaluation terms for beef texture other than 'tenderness.' Longissimus, semitendinosus, and psoas major muscles harvested from three Holstein steers were cooked to 45, 60, 72, and 92 degrees C end-point temperatures and evaluated by a trained sensory panel. Correspondence analysis indicated that the 'chewiness' and 'hardness' defined in ISO5492 were distinguished in each muscle. Changes in the 'chewiness' and 'hardness' qualities during cooking were different from each other. These findings suggest that both 'chewiness' and 'hardness' as defined in ISO5492:1992 should be evaluated simultaneously to determine the sensory texture of beef. Warner-Bratzler shear force values (WBSFVs) were also correlated with ISO5492 'chewiness.' This finding suggests that WBSFV indicates ISO5492 'chewiness' rather than undefined 'tenderness.'
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http://dx.doi.org/10.1016/j.meatsci.2010.05.028DOI Listing
October 2010

Vitamin E as a novel enhancer of macroautophagy in rat hepatocytes and H4-II-E cells.

Biochem Biophys Res Commun 2010 Apr 20;394(4):981-7. Epub 2010 Mar 20.

Laboratory of Nutritional Regulation, Department of Applied Biological Chemistry, Faculty of Agriculture, Graduate School of Science and Technology, Niigata University, 2-8050 Ikarashi, Nishi-ku, Niigata 950-2181, Japan.

Autophagy is an intracellular bulk degradation process induced by nutrient starvation, and contributes to macromolecular turnover and rejuvenation of cellular organelles. We demonstrated that vitamin E was a novel nutritional enhancer of autophagy in freshly isolated rat hepatocytes and rat hepatoma H4-II-E cells. Supplementation of fresh hepatocytes with vitamin E (up to 100 microM) increased proteolysis significantly in the presence or absence of amino acids in a dose-dependent manner. The cytosolic LC3 ratio, a newly established index of autophagic flux, was significantly increased by vitamin E, strongly suggesting that the possible site of action is the LC3 conversion step, an early step in autophagosome formation. A typical antioxidant, alpha-lipoic acid, exerted autophagy suppression, while H(2)O(2) stimulated autophagy. It is conceivable that autophagy was stimulated by oxidative stress and this stimulation was cancelled by cellular antioxidative effects. However, in our studies, vitamin E could have enhanced autophagy over-stimulation by H(2)O(2), rather than suppress it. From these results, using a new cytosolic LC3 ratio, vitamin E increases autophagy by accelerating LC3 conversion through a new signaling pathway, emerging as a novel enhancer of autophagy.
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http://dx.doi.org/10.1016/j.bbrc.2010.03.103DOI Listing
April 2010

Improvement in the in vivo digestibility of rice protein by alkali extraction is due to structural changes in prolamin/protein body-I particle.

Biosci Biotechnol Biochem 2010 7;74(3):614-9. Epub 2010 Mar 7.

Department of Applied Biological Chemistry, Graduate School of Science and Technology, Niigata University, Ikarashi, Niigata, Japan.

Rice prolamin, constituting type-I protein body (PB-I), is indigestible and causes deterioration of rice protein nutritional quality. In this study, the in vivo digestibility of rice protein isolates was investigated by tracing their intraluminal transit in the gastrointestinal (GI) tract of rats by western blotting and by observing the structures excreted in the feces by electron microscopy. Two types of rice protein isolates, produced by alkali extraction (AE-RP) and by starch degradation (SD-RP), were compared. The protein patterns in the isolates were similar, but their digestion in the GI-tract showed striking differences. In the AE-RP group, 13-kDa prolamin (13P) quickly disappeared in the lower GI tract and was not excreted in the feces. By contrast, in the SD-RP group, 13P accumulated massively and nearly intact PB-Is were excreted. These results indicate that the in vivo digestibility of prolamin can be improved by alkali extraction through structural changes to it.
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http://dx.doi.org/10.1271/bbb.90827DOI Listing
July 2010

Cytosolic LC3 ratio as a sensitive index of macroautophagy in isolated rat hepatocytes and H4-II-E cells.

Autophagy 2007 Nov-Dec;3(6):553-60. Epub 2007 Jun 21.

Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Niigata, Japan.

Macroautophagy, an intracellular bulk degradation process in eukaryotes, is sensitive to nutrient supply and deprivation. Microtubule-associated protein 1 light chain 3 (LC3), a mammalian homologue of yeast Atg8, plays an indispensable role in macroautophagy formation and is a suitable marker for this process. Through analysis of the subcellular distribution of LC3, we determined that the cytosolic fraction contained not only a precursor form (LC3-I), but also an apparent active form (LC3-IIs). Both cytosolic LC3-I and LC3-IIs were more responsive to amino acids than those of total homogenate. Moreover, changes in the LC3-IIs/I ratio reflected those in the total proteolytic flux remarkably in both fresh rat hepatocytes and H4-II-E cell lines. Thus, in addition to a sensitive index of macroautophagy, calculating the cytosolic LC3 ratio became an easy and quick quantitative method for monitoring its regulation in hepatocytes and H4-II-E cells.
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http://dx.doi.org/10.4161/auto.4615DOI Listing
January 2008

Effects of rice proteins from two cultivars, Koshihikari and Shunyo, on cholesterol and triglyceride metabolism in growing and adult rats.

Biosci Biotechnol Biochem 2007 Mar 7;71(3):694-703. Epub 2007 Mar 7.

Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Ikarashi, Niigata, Japan.

The effect and mechanism of two types of rice protein, one from regular japonica rice Koshihikari and another from rice cultivar Shunyo, with low glutelin and high prolamin content, on cholesterol and triglyceride metabolism were compared by feeding casein and soy protein to male Wistar strain rats 7 and 20 weeks old ad libitum for 2 weeks. The results in adult rats clearly indicated that both rice proteins had cholesterol-lowering effects in the plasma and the liver, comparable to soy protein, and the effects were accompanied with TG-lowering effects in the liver. Similar effects were also observed in growing rats when the diets were supplemented with cholesterol. The mechanism of the cholesterol-lowering effects by these rice proteins cannot be explained solely by fecal steroid excretion, but the results indicate that not only regular rice protein but also Shunyo rice protein possesses improving effects on lipid metabolism, especially in the adult period.
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http://dx.doi.org/10.1271/bbb.60480DOI Listing
March 2007

Amino acids and insulin control autophagic proteolysis through different signaling pathways in relation to mTOR in isolated rat hepatocytes.

J Biol Chem 2004 Feb 10;279(9):8452-9. Epub 2003 Nov 10.

Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University, Ikarashi, Niigata 950-2181, Japan.

Autophagy, a major bulk proteolytic pathway, contributes to intracellular protein turnover, together with protein synthesis. Both are subject to dynamic control by amino acids and insulin. The mechanisms of signaling and cross-talk of their physiological anabolic effects remain elusive. Recent studies established that amino acids and insulin induce p70 S6 kinase (p70(S6k)) phosphorylation by mTOR, involved in translational control of protein synthesis. Here, the signaling mechanisms of amino acids and insulin in macroautophagy in relation to mTOR were investigated. In isolated rat hepatocytes, both regulatory amino acids (RegAA) and insulin coordinately activated p70(S6k) phosphorylation, which was completely blocked by rapamycin, an mTOR inhibitor. However, rapamycin blocked proteolytic suppression by insulin, but did not block inhibition by RegAA. These contrasting results suggest that insulin controls autophagy through the mTOR pathway, but amino acids do not. Furthermore, micropermeabilization with Saccharomyces aureus alpha-toxin completely deprived hepatocytes of proteolytic responsiveness to RegAA and insulin, but still maintained p70(S6k) phosphorylation by RegAA. In contrast, Leu(8)-MAP, a non-transportable leucine analogue, did not mimic the effect of leucine on p70(S6k) phosphorylation, but maintained the activity on proteolysis. Finally, BCH, a System L-specific amino acid, did not affect proteolytic suppression or mTOR activation by leucine. All the results indicate that mTOR is not common to the signaling mechanisms of amino acids and insulin in autophagy, and that the amino acid signaling starts extracellularly with their "receptor(s)," probably other than transporters, and is mediated through a novel route distinct from the mTOR pathway employed by insulin.
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http://dx.doi.org/10.1074/jbc.M306337200DOI Listing
February 2004