Ingestion of Indigestible Cacao Proteins Promotes Defecation and Alters the Intestinal Microbiota in Mice.

Background: In animals, the health effects of ingested cacao proteins are unknown because the proteins are difficult to extract and purify from cacao beans. Objectives: This study aimed to develop an extraction and purification method for cacao proteins and reveal the effect of ingestion of cacao proteins on defecation and intestinal microbiota in mice. Methods: Three groups of mice were fed a control diet (AIN-93 G), a cacao lignin diet (AIN-93 G containing 1.22% cacao lignin), or a cacao protein and lignin diet (AIN-93 G containing 1.97% cacao proteins and 1.22% cacao lignin) by pair-feeding for 8 d. Feces were collected as 2 bulked samples from days 1 to 4 and days 5 to 8 on each diet. The collected feces were weighed and the intestinal microbiota was analyzed by next-generation sequencing-based 16S rRNA. Results: A new extraction and purification method for cacao proteins has been developed, then found that the proteins are resistant to digestive enzymes. However, the cacao protein powder made by this method contained 34.9% of lignin in addition to 56.4% of proteins. Therefore, to reveal the effect by cacao proteins alone, the fecal weight and intestinal microbiota of mice fed the cacao protein and lignin diet were compared with those of mice fed the cacao lignin diet. The fecal weight of mice fed the cacao protein and lignin diet was significantly greater than of mice fed the cacao lignin diet. The relative abundance of Lactococcus and Mucispirillum species in mice fed the cacao protein and lignin diet was significantly higher than in mice fed the cacao lignin diet, but the relative abundance of Anaerotruncus, Oscillospira, and Roseburia species in mice fed the cacao protein and lignin diet was significantly lower than in mice fed the cacao lignin diet. Conclusions: Ingestion of indigestible cacao proteins promoted defecation and altered the intestinal microbiota such as Lactococcus, Mucispirillum, Anaerotruncus, Oscillospira, and Roseburia species in mice.

A new method for the preparation of a purified glucosylceramide and ceramide from shiitake mushroom.

Ingestion of plant and fungal glucosylceramides is known to reduce colon carcinogenesis and skin barrier damage in mice and humans. However, such effects in animal experiments have not been revealed for plant and fungal ceramides because the content of ceramides contained in plants and fungi is so low that the large amount required for animal experiments is difficult to obtain. Noting that the fungus shiitake mushroom (Lentinula edodes) is rich in a glucosylceramide, (4E,8E)-N-d-2'-hydroxypalmitoyl-1-O-ß-d-glucopyranosyl-9-methyl-4,8-sphingadienine [Glc-d19:2(4E,8E,9Me)-h16:0], we developed a new method to purify this fungal glucosylceramide using ethanol precipitation and high-performance liquid chromatography. We also developed a new method to produce large amounts of a ceramide [d19:2(4E,8E,9Me)-h16:0] from this purified glucosylceramide using human glycoside hydrolase family 30 glucocerebrosidase (imiglucerase). These methods will be useful for elucidating the physiological function by ingestion of fungal ceramides in animal experiments.

Sphingadienine-1-phosphate levels are regulated by a novel glycoside hydrolase family 1 glucocerebrosidase widely distributed in seed plants.

Long-chain base phosphates (LCBPs) such as sphingosine-1-phosphate and phytosphingosine-1-phosphate function as abscisic acid (ABA)-mediated signaling molecules that regulate stomatal closure in plants. Recently, a glycoside hydrolase family 1 (GH1) ß-glucosidase, Os3BGlu6, was found to improve drought tolerance by stomatal closure in rice, but the biochemical functions of Os3BGlu6 have remained unclear. Here we identified Os3BGlu6 as a novel GH1 glucocerebrosidase (GCase) that catalyzes the hydrolysis of glucosylceramide to ceramide. Phylogenetic and enzymatic analyses showed that GH1 GCases are widely distributed in seed plants and that pollen or anthers of all seed plants tested had high GCase activity, but activity was very low in ferns and mosses. Os3BGlu6 had high activity for glucosylceramides containing (4E,8Z)-sphingadienine, and GCase activity in leaves, stems, roots, pistils, and anthers of Os3BGlu6-deficient rice mutants was completely absent relative to that of wild-type rice. The levels of ceramides containing sphingadienine were correlated with GCase activity in each rice organ and were significantly lower in Os3BGlu6-deficient rice mutants than in the wild type. The levels of LCBPs synthesized from ceramides, especially the levels of sphingadienine-1-phosphate, were also correlated with GCase activity in each rice organ and were significantly lower in Os3BGlu6-deficient rice mutants than in the wild type. These results indicate that Os3BGlu6 regulates the level of ceramides containing sphingadienine, influencing the regulation of sphingadienine-1-phosphate levels and subsequent improvement of drought tolerance via stomatal closure in rice.

Direct LC-ESI-MS/MS analysis of plant glucosylceramide and ceramide species with 8E and 8Z isomers of the long chain base.

Glucosylceramides and ceramides with 8E and 8Z isomers of the long chain base are found in plants. These isomers have been difficult to quantify separately using liquid chromatography-tandem mass spectrometry (LC-MS/MS) because the isomers have the same retention time, their precursor and product ions have the same m/z values, and plant ceramide standards are not commercially available. Here we tested trial separations using various ODS columns and prepared plant ceramide standards generated by human glucocerebrosidase (imiglucerase) using commercially available plant glucosylceramide standards as the substrates. Consequently, we were able to quantify the isomers based on differences in retention times in a TSKgel ODS-120A column (Tosoh, Tokyo Japan) using LC-electrospray ionization-MS/MS (LC-ESI-MS/MS).

Fructooligosaccharides suppress high-fat diet-induced fat accumulation in C57BL/6J mice.

Two experiments were performed to examine the effects of fructooligosaccharides (FOS) on the development of obesity. In the first experiment, Wistar rats were orally administered a 2.5 g/kg body weight lipid emulsion containing FOS, and the subsequent elevation of plasma triglycerides was significantly suppressed compared with that in rats receiving lipid emulsion alone. In the second experiment, C57BL/6J male mice were fed a high-fat "western" diet with or without 2.5% FOS supplementation (n = 10/group) ad libitum for 12 weeks. Body weight and percent body fat were lower in mice fed FOS than in controls. Furthermore, the weight of the visceral adipose tissue, and the weight and triglyceride content of the liver were significantly lower in the high-fat + FOS group. Fecal excretion of lipids was markedly enhanced by FOS consumption. These results indicate that dietary FOS suppress high-fat diet-induced body fat accumulation, and inhibit intestinal absorption of dietary fat.

Identification of UV-Induced Diterpenes Including a New Diterpene Phytoalexin, Phytocassane F, from Rice Leaves by Complementary GC/MS and LC/MS Approaches.

Rice phytoalexins are regarded as one of the most important weapons against pathogenic microorganisms. We attempted to identify novel phytoalexins and their derivatives using GC/MS and LC/MS analyses. Diterpene derivatives, 9ß-pimara-7,15-diene-3ß,6ß,19-triol, 1, stemar-13-en-2α-ol, 2, and 1α,2α-dihydroxy-ent-12,15-cassadiene-3,11-dione, 3, were isolated from UV-irradiated rice leaves by chromatographic methods. These structures were confirmed by 1D- and 2D-NMR and MS analyses. Interestingly, all three compounds were accumulated following an infection by the rice blast pathogen Magnaporthe oryzae. Compounds 1 and 2 exhibited weak antifungal activity and may be the biosynthetic intermediates of rice phytoalexins momilactones and oryzalexin S, respectively. Compound 3 exhibited relatively high inhibitory activity against the fungal mycelial growth of M. oryzae to the same extent as the known phytoalexin phytocassane A. We conclude that 3 is a member of the cassane-type phytoalexin family and propose the name phytocassane F.

Reverse-genetic approach to verify physiological roles of rice phytoalexins: characterization of a knockdown mutant of OsCPS4 phytoalexin biosynthetic gene in rice.

A variety of labdane-related diterpenoids, including phytocassanes, oryzalexins and momilactones, were identified as phytoalexins in rice (Oryza sativa L.). Momilactone B was also isolated as an allelochemical exuded from rice roots. The biosynthetic genes of these phytoalexins have been identified, including six labdane-related diterpene cyclase genes such as OsCPS2, OsCPS4, OsKSL4, OsKSL7, OsKSL8 and OsKSL10. Here we identified an OsCPS4 knockdown mutant, cps4-tos, by screening Tos17 mutant lines using polymerase chain reaction. OsCPS4 encodes a syn-copalyl diphosphate synthase responsible for momilactones and oryzalexin S biosynthesis. Because Tos17 was inserted into the third intron of OsCPS4, the mature OsCPS4 mRNA was detected in the cps4-tos mutant as well as the wild type. Nevertheless, mature OsCPS4 transcript levels in the cps4-tos mutant were about one sixth those in the wild type. The cps4-tos mutant was more susceptible to rice blast fungus than the wild type, possibly due to lower levels of momilactones and oryzalexin S in the mutant. Moreover, co-cultivation experiments suggested that the allelopathic effect of cps4-tos against some kinds of lowland weeds was significantly lower than that of the wild type, probably because of lower momilactone content exuded from cps4-tos roots. A reverse-genetic strategy using the cps4-tos mutant showed the possible roles of momilactones not only as phytoalexins but also as allelopathic substances.

Collagen hydrolysate intake improves the loss of epidermal barrier function and skin elasticity induced by UVB irradiation in hairless mice.

BACKGROUND: Ultraviolet B (UVB) irradiation induces serious damage to the skin. Collagen hydrolysate and collagen-derived peptides have effects on skin function in vivo and in vitro. However, few studies have investigated changes in the epidermal barrier or dermal elasticity caused by UVB. Here, we investigated the loss of epidermal barrier function and skin elasticity induced by UVB irradiation in hairless mice fed collagen hydrolysate. METHODS: Mice were orally administered collagen hydrolysate, in a single dose (20 mJ/cm(2) ) or repeated doses (10-30 mJ/cm(2) , 3 times/week for 6 weeks), and the dorsal skin was exposed to UVB. Skin measurements and histological and analytical studies were performed. RESULTS: In control mice, a single UVB irradiation induced epidermal barrier dysfunction including an increase in transepidermal water loss (TEWL), epidermal hyperplasia, and a decrease in stratum corneum water content. Administration of collagen hydrolysate significantly decreased TEWL and epidermal thickness and increased stratum corneum water content. Repeated UVB irradiation decreased skin elasticity and dermal hyaluronic acid (HA) content in control mice, whereas collagen hydrolysate significantly suppressed both the increase in TEWL and the decrease in stratum corneum water content and improved skin elasticity and dermal HA content. CONCLUSIONS: Collagen hydrolysate administration affects epidermal barrier function and dermal skin elasticity.

Post-exercise whey protein hydrolysate supplementation induces a greater increase in muscle protein synthesis than its constituent amino acid content.

It is well known that ingestion of a protein source is effective in stimulating muscle protein synthesis after exercise. In addition, there are numerous reports on the impact of leucine and leucine-rich whey protein on muscle protein synthesis and mammalian target of rapamycin (mTOR) signalling. However, there is only limited information on the effects of whey protein hydrolysates (WPH) on muscle protein synthesis and mTOR signalling. The aim of the present study was to compare the effects of WPH and amino acids on muscle protein synthesis and the initiation of translation in skeletal muscle during the post-exercise phase. Male Sprague­Dawley rats swam for 2 h to depress muscle protein synthesis. Immediately after exercise, the animals were administered either carbohydrate (CHO), CHO plus an amino acid mixture (AA) or CHO plus WPH. At 1 h after exercise, the supplements containing whey-based protein (AA and WPH) caused a significant increase in the fractional rate of protein synthesis (FSR) compared with CHO. WPH also caused a significant increase in FSR compared with AA. Post-exercise ingestion of WPH caused a significant increase in the phosphorylation of mTOR levels compared with AA or CHO. In addition, WPH caused greater phosphorylation of ribosomal protein S6 kinase and eukaryotic initiation factor 4E-binding protein 1 than AA and CHO. In contrast, there was no difference in plasma amino acid levels following supplementation with either AA or WPH. These results indicate that WPH may include active components that are superior to amino acids for stimulating muscle protein synthesis and initiating translation.

Differential effects of black currant anthocyanins on diffuser- or negative lens-induced ocular elongation in chicks.

PURPOSE: To compare the inhibitory effects of 4 different types of black currant anthocyanins (BCAs) on ocular elongation in 2 different chick myopia models. METHODS: In the first model, diffusers were used to induce form vision deprivation. In the second model, negative (-8D) spherical lenses were used to create a defocused retinal image. Either the diffusers or the -8D lenses were placed on the right eyes of 8-day-old chicks for 4 days. Ocular biometric components were measured using an A-scan ultrasound instrument on the third day after application of either the diffusers or -8D lenses. Interocular differences (globe component dimensions of the right diffuser or eyes covered with -8D lenses minus those of the open left eyes) were considered to evaluate the effect of BCAs. The BCAs used were cyanidin-3-glucoside (C3G), cyanidin-3-rutinoside (C3R), delphinidin-3-rutinoside (D3R), and delphinidin-3-glucoside (D3G). Each anthocyanin was administered intravenously at a dose of 0.027 µmol/kg once a day for 3 days. RESULTS: Compared to the vehicle treatment, C3G and C3R treatments significantly reduced both differential increases (positive values of interocular differences) of the ocular axial length induced by diffusers or -8D lenses (diffusers; C3G, C3R, and control: 0.32±0.051 mm, P<0.05; 0.25±0.034 mm, P<0.01; and 0.52±0.047 mm, -8D lenses; C3G, C3R, and control: 0.25±0.049 mm, P<0.01; 0.17±0.049 mm, P<0.001; and 0.50±0.056 mm). In contrast, compared to vehicle treatment, D3R treatment significantly decreased the differential increases in the ocular axial length only in chicks with myopia induced by -8D lenses (D3R and control: 0.17±0.049 mm and 0.50±0.056 mm, P<0.001). D3G did not inhibit the differential increase in the ocular axial length induced by either diffusers or -8D lenses. CONCLUSIONS: This study showed that the 4 tested BCAs had different effects on the 2 different experimental models of myopia.

Dietary whey protein hydrolysates increase skeletal muscle glycogen levels via activation of glycogen synthase in mice.

Previously, we have shown that consuming carbohydrate plus whey protein hydrolysates (WPHs) replenished muscle glycogen after exercise more effectively than consuming intact whey protein or branched-chain amino acids (BCAAs). The mechanism leading to superior glycogen replenishment after consuming WPH is unclear. In this 5 week intervention, ddY mice were fed experimental diets containing WPH, a mixture of whey amino acids (WAAs), or casein (control). After the intervention, gastrocnemius muscle glycogen levels were significantly higher in the WPH group (4.35 mg/g) than in the WAA (3.15 mg/g) or control (2.51 mg/g) groups. In addition, total glycogen synthase (GS) protein levels were significantly higher in the WPH group (153%) than in the WAA (89.2%) or control groups, and phosphorylated GS levels were significantly decreased in the WPH group (51.4%). These results indicate that dietary WPH may increase the muscle glycogen content through increased GS activity.

Comparison of fructooligosaccharide utilization by Lactobacillus and Bacteroides species.

The utilization of 1-kestose (GF(2)) and nystose (GF(3)), the main components of fructooligosaccharides (FOS), by Lactobacillus and Bacteroides species was examined. Of seven Lactobacillus and five Bacteroides strains that utilized FOS, L. salivarius, L. rhamnosus, L. casei, and L. gasseri utilized only GF(2), whereas L. acidophilus and all the Bacteroides strains utilized both GF(2) and GF(3). Only the strains able to utilize both GF(2) and GF(3) had ß-fructosidase activity in the culture supernatants. The culture supernatants of the Lactobacillus strains had higher ß-fructosidase activity for GF(2) than for GF(3), whereas those of the Bacteroides strains had higher activity for GF(3) than for GF(2). Furthermore, ß-fructosidase activity of the culture supernatants of the Lactobacillus cells grown in the GF(3) medium was much higher than that of the cells grown in the GF(2) medium, whereas the activity of the culture supernatants of the Bacteroides cells grown in the GF(3) medium was almost the same as that of the cells grown in the GF(2) medium. These results indicate that Lactobacillus species metabolize FOS in a different way from that of Bacteroides species.

Regulation of a proteinaceous elicitor-induced Ca2+ influx and production of phytoalexins by a putative voltage-gated cation channel, OsTPC1, in cultured rice cells.

Pathogen/microbe- or plant-derived signaling molecules (PAMPs/MAMPs/DAMPs) or elicitors induce increases in the cytosolic concentration of free Ca(2+) followed by a series of defense responses including biosynthesis of antimicrobial secondary metabolites called phytoalexins; however, the molecular links and regulatory mechanisms of the phytoalexin biosynthesis remains largely unknown. A putative voltage-gated cation channel, OsTPC1 has been shown to play a critical role in hypersensitive cell death induced by a fungal xylanase protein (TvX) in suspension-cultured rice cells. Here we show that TvX induced a prolonged increase in cytosolic Ca(2+), mainly due to a Ca(2+) influx through the plasma membrane. Membrane fractionation by two-phase partitioning and immunoblot analyses revealed that OsTPC1 is localized predominantly at the plasma membrane. In retrotransposon-insertional Ostpc1 knock-out cell lines harboring a Ca(2+)-sensitive photoprotein, aequorin, TvX-induced Ca(2+) elevation was significantly impaired, which was restored by expression of OsTPC1. TvX-induced production of major diterpenoid phytoalexins and the expression of a series of diterpene cyclase genes involved in phytoalexin biosynthesis were also impaired in the Ostpc1 cells. Whole cell patch clamp analyses of OsTPC1 heterologously expressed in HEK293T cells showed its voltage-dependent Ca(2+)-permeability. These results suggest that OsTPC1 plays a crucial role in TvX-induced Ca(2+) influx as a plasma membrane Ca(2+)-permeable channel consequently required for the regulation of phytoalexin biosynthesis in cultured rice cells.

The effect of high-intensity intermittent swimming on post-exercise glycogen supercompensation in rat skeletal muscle.

A single bout of prolonged endurance exercise stimulates glucose transport in skeletal muscles, leading to post-exercise muscle glycogen supercompensation if sufficient carbohydrate is provided after the cessation of exercise. Although we recently found that short-term sprint interval exercise also stimulates muscle glucose transport, the effect of this type of exercise on glycogen supercompensation is uncertain. Therefore, we compared the extent of muscle glycogen accumulation in response to carbohydrate feeding following sprint interval exercise with that following endurance exercise. In this study, 16-h-fasted rats underwent a bout of high-intensity intermittent swimming (HIS) as a model of sprint interval exercise or low-intensity prolonged swimming (LIS) as a model of endurance exercise. During HIS, the rats swam for eight 20-s sessions while burdened with a weight equal to 18% of their body weight. The LIS rats swam with no load for 3 h. The exercised rats were then refed for 4, 8, 12, or 16 h. Glycogen levels were almost depleted in the epitrochlearis muscles of HIS- or LIS-exercised rats immediately after the cessation of exercise. A rapid increase in muscle glycogen levels occurred during 4 h of refeeding, and glycogen levels had peaked at the end of 8 h of refeeding in each group of exercised refed rats. The peak glycogen levels during refeeding were not different between HIS- and LIS-exercised refed rats. Furthermore, although a large accumulation of muscle glycogen in response to carbohydrate refeeding is known to be associated with decreased insulin responsiveness of glucose transport, and despite the fact that muscle glycogen supercompensation was observed in the muscles of our exercised rats at the end of 4 h of refeeding, insulin responsiveness was not decreased in the muscles of either HIS- or LIS-exercised refed rats compared with non-exercised fasted control rats at this time point. These results suggest that sprint interval exercise enhances muscle glycogen supercompensation in response to carbohydrate refeeding as well as prolonged endurance exercise does. Furthermore, in this study, both HIS and LIS exercise prevented insulin resistance of glucose transport in glycogen supercompensated muscle during the early phase of carbohydrate refeeding. This probably led to the enhanced muscle glycogen supercompensation after exercise.

A new glycosylated dihydrophaseic acid from cacao germs (Theobroma cacao L.).

Cacao beans are composed of cacao nibs and germs. Although numerous chemical and physiological studies on cacao nib compounds have been reported, there is little information on cacao germ compounds. We therefore analyzed an extract from the cacao germ, and found two compounds that were specific to the germ. One of these two compounds was identified as the new glycosylated abscisic acid metabolite, dihydrophaseic acid-4'-O-6″-(ß-ribofuranosyl)-ß-glucopyranoside, and the other as the known compound, dihydrophaseic acid-4'-O-ß-D-glucopyranoside.

Cacao polyphenols influence the regulation of apolipoprotein in HepG2 and Caco2 cells.

Cocoa powder is rich in polyphenols, such as catechins and procyanidins, and has been shown to inhibit low-density lipoprotein (LDL) oxidation and atherogenesis in a variety of models. Human studies have also shown daily intake of cocoa increases plasma high-density lipoprotein (HDL) and decreases LDL levels. However, the mechanisms responsible for these effects of cocoa on cholesterol metabolism have yet to be fully elucidated. The present study investigated the effects of cacao polyphenols on the production of apolipoproteins A1 and B in human hepatoma HepG2 and intestinal Caco2 cell lines. The cultured HepG2 cells or Caco2 cells were incubated for 24 h in the presence of cacao polyphenols such as (-)-epicatechin, (+)-catechin, procyanidin B2, procyanidin C1, and cinnamtannin A2. The concentration of apolipoproteins in the cell culture media was quantified using an enzyme-linked immunoassay, and the mRNA expression was quantified by RT-PCR. Cacao polyphenols increased apolipoprotein A1 protein levels and mRNA expression, even though apolipoprotein B protein and the mRNA expression were slightly decreased in both HepG2 cells and Caco2 cells. In addition, cacao polyphenols increased sterol regulatory element binding proteins (SREBPs) and activated LDL receptors in HepG2 cells. These results suggest that cacao polyphenols may increase the production of mature form SREBPs and LDL receptor activity, thereby increasing ApoA1 and decreasing ApoB levels. These results elucidate a novel mechanism by which HDL cholesterol levels become elevated with daily cocoa intake.

Dietary whey hydrolysate with exercise alters the plasma protein profile: a comprehensive protein analysis.

OBJECTIVE: It has been shown that dietary whey protein accelerates glucose uptake by altering glycoregulatory enzyme activity in skeletal muscle. In the present study, we investigated the effect of dietary whey protein on endurance and glycogen resynthesis and attempted to identify plasma proteins that reflected the physical condition by a comprehensive proteomics approach. METHODS: Male c57BL/6 mice were divided into four groups: sedentary, sedentary with whey protein hydrolysate, exercise, and exercise with whey protein hydrolysate. The mice in the exercise groups performed treadmill running exercise five times per week for 4 wk. Protein profiling of plasma sample obtained from individuals was performed, as were measurements of endurance performance and the glycogen content of gastrocnemius muscle. RESULTS: After the training period, the endurance of mice fed the whey diet was improved compared with that of mice fed the control diet. Muscle glycogen content was significantly increased after 4 wk of exercise, and intake of whey protein led to a further increase in glycogen. Apolipoproteins A-II and C-I and ß(2)-glycoprotein-1 were found to be altered by training combined with the intake of whey protein, without significant changes induced by exercise or whey protein alone. CONCLUSION: Results of the present study suggest that these three proteins may be potential biomarkers of improved endurance and glycogen resynthesis and part of the mechanism that mediates the benefits of whey protein.

Preexercise ingestion of carbohydrate plus whey protein hydrolysates attenuates skeletal muscle glycogen depletion during exercise in rats.

OBJECTIVE: Depletion of glycogen stores is associated with fatigue during both sprint and endurance exercises and therefore it is considered important to maintain adequate tissue stores of glycogen during exercise. The aims of the present study in rats were therefore to investigate the effects of preexercise supplementation with carbohydrate and whey protein hydrolysates (WPH) on glycogen content, and phosphorylated signaling molecules of key enzymes that regulate glucose uptake and glycogen synthesis during exercise. METHODS: Male SD rats were used in the study (n=7/group). Prior to exercise, one group of rats was sacrificed, whereas the other groups were given either water, glucose, or glucose plus WPH solutions. After ingestion of the test solutions, glycogen-depleting exercise was carried out for 60 min. The rats were then sacrificed and the triceps muscles excised quickly. RESULTS: Compared to water or glucose only, preexercise ingestion of glucose plus WPH caused a significant attenuation of muscle glycogen depletion during the postexercise period. Coingestion of glucose and WPH also significantly lowered phosphorylated glycogen synthase levels compared to ingestion of water only. In the glucose plus WPH group, the levels of phosphorylated Akt were increased significantly compared to the group ingesting water only, while the levels of phosphorylated PKC were significantly higher than in the groups ingesting only water or glucose. CONCLUSION: Taken together, these results indicate that, compared to ingestion of glucose or water only, preexercise ingestion of carbohydrate plus WPH activates skeletal muscle proteins of key enzymes that regulate glucose uptake and glycogen synthesis during exercise, thereby attenuating exercise-induced glycogen depletion.

Comparison of different sources and degrees of hydrolysis of dietary protein: effect on plasma amino acids, dipeptides, and insulin responses in human subjects.

The effect of protein fractionation on the bioavailability of amino acids and peptides and insulin response and whether the protein source influences these effects in humans are poorly understood. This study compared the effects of different sources and degrees of hydrolysis of dietary protein, independent of carbohydrate, on plasma amino acid and dipeptide levels and insulin responses in humans. Ten subjects were enrolled in the study, with five subjects participating in trials on either soy or whey protein and their hydrolysates. Protein hydrolysates were absorbed more rapidly as plasma amino acids compared to nonhydrolyzed protein. Whey protein also caused more rapid increases in indispensable amino acid and branched-chain amino acid concentrations than soy protein. In addition, protein hydrolysates caused significant increases in Val-Leu and Ile-Leu concentrations compared to nonhydrolyzed protein. Whey protein hydrolysates also induced significantly greater stimulation of insulin release than the other proteins. Taken together, these results demonstrate whey protein hydrolysates cause significantly greater increases in the plasma concentrations of amino acids, dipeptides, and insulin.

Phytoalexin accumulation in the interaction between rice and the blast fungus.

Blast fungus-induced accumulations of major rice diterpene phytoalexins (PA), momilactones A and B, and phytocassanes A through E were studied, focusing on their biosynthesis and detoxification. In resistant rice, all PA started to accumulate at 2 days postinoculation (dpi), at which hypersensitive reaction (HR)-specific small lesions became visible and increased 500- to 1,000-fold at 4 dpi, while the accumulation was delayed and several times lower in susceptible rice. Expression of PA biosynthetic genes was transiently induced at 2 dpi only in resistant plants, while it was highly induced in both plants at 4 dpi. Fungal growth was severely suppressed in resistant plants by 2 dpi but considerably increased at 3 to 4 dpi in susceptible plants. Momilactone A treatment suppressed fungal growth in planta and in vitro, and the fungus detoxified the PA in vitro. These results indicate that HR-associated rapid PA biosynthesis induces severe restriction of fungus, allowing higher PA accumulation in resistant rice, while in susceptible rice, failure of PA accumulation at the early infection stage allows fungal growth. Detoxification of PA would be a tactic of fungus to invade the host plant, and prompt induction of PA biosynthesis upon HR would be a trait of resistant rice to restrict blast fungus.