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The effect of wheat bran particle size on laxation and colonic fermentation.

OBJECTIVE: Due to perceived inferior fecal bulking ability, finely ground wheat bran is not recommended for treatment of colonic disorders, despite possible short chain fatty acid generation with potential benefits for colonic mucosal health. We therefore tested the effects of very fine particle size wheat bran on colonic function. METHODS: Two studies, each with three phases, were undertaken in healthy subjects in a randomized crossover design. In one study (metabolic, n=23) subjects took three diets containing either an additional 19 g/d dietary fiber with mean particle size (MPS) 50 microm or 758 microm in bread or a control low fiber bread. In the other study where the supplement was provided as a breakfast cereal (ad libitum, n=24) the respective wheat bran MPS were 692 microm and 1158 microm and the control was low fiber. Fecal collections were obtained during the last week of each diet. In the metabolic study, fecal short chain fatty acids were measured and 12-hour breath gas collections obtained. RESULTS: In both studies, wheat bran supplements significantly increased fecal bulk compared to the control (p<0.004), with no significant differences between brans of different particle size and no differences in fecal water content. However, higher fecal butyrate concentrations (p<0.007), butyrate output and breath CH4 levels (p=0.025) were seen on the low MPS wheat bran compared to the other two treatments, suggesting increased bacterial fermentation. CONCLUSIONS: Fine MPS wheat bran is an effective fecal bulking agent and may have added advantages if increased butyrate concentrations promote colonic mucosal integrity.

Adult↗

Effect of flaxseed and wheat bran on serum hormones and lignan excretion in premenopausal women.

OBJECTIVE: To examine the effects of flaxseed consumption (a lignan-rich plant food) alone and in combination with wheat bran on serum hormones and urinary lignan excretion in premenopausal women. METHODS: Sixteen subjects were studied for four feeding treatments lasting two menstrual cycles each in a randomized, crossover design. During each treatment, subjects consumed their habitual diets supplemented with baked goods containing no flaxseed or wheat bran, 10 g of flaxseed, 28 g of wheat bran, or 10 g of flaxseed plus 28 g of wheat bran/day. Serum samples collected during the mid-luteal phase of the second menstrual cycle of each diet treatment were analyzed for serum hormones and sex hormone binding globulin. Urine samples collected during the same time period were analyzed for urinary lignan excretion. RESULTS: There were no changes in serum hormone concentrations or sex hormone binding globulin on any of the treatments. Urinary lignan excretion significantly increased on diet treatments that included flaxseed, but inclusion of wheat bran did not significantly alter lignan excretion. CONCLUSIONS: Urinary lignan excretion increased with flaxseed consumption, but serum hormones did not change in this group of premenopausal women. Consumption of wheat bran with flaxseed did not alter urinary lignan excretion associated with flaxseed consumption.

Adult↗

An investigation into the variability of extract viscosity of wheat-relationship with the content of non-starch-polysaccharide fractions and metabolisable energy for broiler chickens.

The in vitro extract-viscosity and the content of non-starch-polysaccharides were investigated in 34 defined wheat varieties grown at 5 locations each. Both, wheat genotype as well as growing location clearly influenced the viscosity of soluble extract from wheat. Furthermore, the content of non-starch-polysaccharides (soluble/total) and pentosans (soluble/total) were determined in 13 wheat varieties each grown at two locations. Soluble pentosan contents were highly positively correlated with extract viscosity of wheat at the locations Hayn (r = 0.86) and Biendorf (r = 0.90). The classical apparent metabolisable energy of 5 wheat samples having different extract viscosities was assessed. The AMEN values ranged from 14.0 to 14.6 MJ/kg DM and were significant negatively correlated to content of soluble arabinoxylans (r = 0.67) and to the extract viscosity (r = 0.83). Furthermore, the viscosity of jejunal (4.0 to 22.8 mPas) and ileal (13.1 to 78.0 mPas) digesta exhibited a clear relationship with soluble pentosan contents and extract viscosity. Under the conditions applied in this study the technique of extract viscosity measurement can predict the AME.

Analysis of Variance↗

Influence of stress protein CSP 310 and antiserum against this protein on oxygen uptake, lipid peroxidation, and temperature of winter wheat seedling shoots during cold stress.

It is determined that infiltration of winter wheat seedling shoots by anti-CSP 310 antiserum caused a significant decrease of oxygen uptake in winter wheat shoots during short-term cold stress. On the other hand, infiltration of winter wheat seedling shoots by stress protein CSP 310 caused an increase of oxygen consumption. The comparison of the influence of infiltration of winter wheat shoots by CSP 310 and anti-CSP 310 antiserum on the rate of lipid peroxidation showed that, if infiltration by CSP 310 caused a decrease of conjugated diene formation, infiltration by anti-CSP 310 antiserum did not cause any significant changes in the rate of lipid peroxidation. The study of the influence of infiltration of winter wheat shoots by CSP 310 and anti-CSP 310 antiserum on the temperature of winter wheat shoots during cold stress showed that CSP 310 caused the increase of their temperature while anti-CSP 310 caused a decrease of their temperature.

Cold Temperature↗

Whole-grain rye and wheat foods and markers of bowel health in overweight middle-aged men.

BACKGROUND: Whole-grain cereal foods including rye have been identified as providing significant health benefits that do not occur when refined-cereal foods are ingested. OBJECTIVES: Foods (90 g) containing whole-grain rye flour and whole-grain wheat flour were compared with low-fiber refined-cereal foods for their effects on markers of bowel health and the metabolic markers insulin and glucose. DESIGN: Three 4-wk interventions were undertaken in a randomized crossover design with 28 overweight men aged 40-65 y who had no history of bowel disease. Against a background intake of 14 g dietary fiber (DF), the men were fed low-fiber cereal grain foods providing 5 g DF for a total of 19 g DF/d. High-fiber wheat foods provided 18 g DF, and high-fiber rye foods provided 18 g DF, both giving a total of 32 g DF/d. Fecal samples (48-h) and fasting and postprandial blood samples were collected at the end of each period and assayed. RESULTS: Both high-fiber rye and wheat foods increased fecal output by 33-36% (P = 0.004) and reduced fecal beta-glucuronidase activity by 29% (P = 0.027). Postprandial plasma insulin was decreased by 46-49% (P = 0.0001) and postprandial plasma glucose by 16-19% (P = 0.0005). Rye foods were associated with significantly (P = 0.0001) increased plasma enterolactone (47% and 71%) and fecal butyrate (26% and 36%), relative to wheat and low-fiber options, respectively. CONCLUSIONS: High-fiber rye and wheat food consumption improved several markers of bowel and metabolic health relative to that of low-fiber food. Fiber from rye appears more effective than that from wheat in overall improvement of biomarkers of bowel health.

4-Butyrolactone↗

Postprandial metabolic utilization of wheat protein in humans.

BACKGROUND: The quality of cereal protein has been little studied in humans despite its quantitative importance in the diet, particularly in developing countries. OBJECTIVE: The objective of this study was to determine the nutritional value of wheat protein in humans as assessed by the measurement of their real ileal digestibility and postprandial retention. DESIGN: Healthy young adults (n = 14) were fitted with an intestinal tube to allow the collection of intestinal fluid in the duodenum or terminal ileum. Subjects received a mixed meal of 136 g wheat toast that contained 24.6 g uniformly and intrinsically [(15)N]-labeled wheat protein. Intestinal fluid, blood, and urine were collected for 8 h postprandially. RESULTS: The real ileal digestibility of dietary wheat nitrogen amounted to 90.3 +/- 4.3%. The cumulative amount of dietary nitrogen transferred to the deamination pools reached a plateau at 8 h of 24.7 +/- 6.8% of the amount ingested. The urinary excretion of dietary nitrogen in ammonia was high (0.8 +/- 0.3% of ingested dose). The incorporation of dietary nitrogen into serum protein reached 7.0 +/- 1.9% of the meal. Postprandial wheat protein retention was 66.1 +/- 5.8%. CONCLUSIONS: Our results show that wheat proteins had the same true ileal digestibility as did most of the plant proteins already studied in humans, but also that they had a lower postprandial nitrogen retention value. However, this low value was higher than that predicted from the calculation of indispensable amino acid scores, ie, 89% rather than 30-40% of the nutritional value of milk proteins.

Adult↗

Relationships among vernalization, shoot apex development and frost tolerance in wheat.

BACKGROUND AND AIMS: Frost tolerance of wheat depends primarily upon a strong vernalization requirement, delaying the transition to the reproductive phase. The aim of the present study was to learn how saturation of the vernalization requirement and apical development stage are related to frost tolerance in wheat. METHODS: 'Mironovskaya 808', a winter variety with a long vernalization requirement, and 'Leguan', a spring variety without a vernalization requirement, were acclimated at 2 degrees C at different stages of development. Plant development (morphological stage of the shoot apex), vernalization requirement (days to heading) and frost tolerance (survival of the plants exposed to freezing conditions) were evaluated. KEY RESULTS: 'Mironovskaya 808' increased its frost tolerance more rapidly; it reached a higher level of tolerance and after a longer duration of acclimation at 2 degrees C than was found in 'Leguan'. The frost tolerance of 'Mironovskaya 808' decreased and its ability to re-acclimate a high tolerance was lost after saturation of its vernalization requirement, but before its shoot apex had reached the double-ridge stage. The frost tolerance of 'Leguan' decreased after the plants had reached the floret initiation stage. CONCLUSIONS: The results support the hypothesis that genes for vernalization requirement act as a master switch regulating the duration of low temperature induced frost tolerance. In winter wheat, due to a longer vegetative phase, frost tolerance is maintained for a longer time and at a higher level than in spring wheat. After the saturation of vernalization requirement, winter wheat (as in spring wheat) established only a low level of frost tolerance.

Acclimatization↗

Age-dependent transformation frequency in elite wheat varieties.

Wheat is a major world crop and as such is a primary target for improvement of agronomic characteristics via genetic engineering. Optimization of transformation is essential in order to overcome the relatively low transformation frequencies encountered with wheat. Transformation of elite wheat varieties is not always successful due to variability in regeneration and transformation frequencies between varieties. In this work, two elite wheat varieties with a relatively high embryogenic capacity were transformed by particle bombardment. A strong correlation between transformation frequency and the age of wheat donor plants was observed in both varieties. The mean transformation frequency rose from 0.7% to 5% when using immature embryos from old and young donor plants, respectively. This was observed in both varieties, the best bombardments achieving up to 7.3% frequency. Using explants at an optimal developmental stage from donor plants grown under environmentally-controlled conditions has improved the reproducibility of transformation efficiency of elite wheat varieties and leads to the production of apparently phenotypically normal, fertile, transgenic plants.

Base Sequence↗

The transfer and history of "reduced height genes" (Rht) in wheat from Japan to Europe.

Wheat is the main crop and often a strategic crop in many European countries. From a historical perspective, we describe the transfer of "reduced height genes" (Rht genes) from Japanese wheat varieties to wheat varieties in Europe and their influence on the increase of the total wheat production in the last century. Historic pathways of Rht genes were influenced directly or indirectly by wheat breeders exchanging seed samples and by some governments importing large quantities of wheat during historically critical periods for their countries.

Europe↗

Beneficial effect of wheat germ on circulating lipoproteins and tissue lipids in rats fed a high fat, cholesterol-containing diet.

Adult male rats were fed for 7 wk either a low fat diet (3% fat) or a high fat-cholesterol diet (20% fat, 0.5% cholesterol) containing 7% wheat germ or not. Body weights and food intakes were unchanged by adding wheat germ to the control low fat or high fat diets. Adding wheat germ to the high fat-cholesterol diet significantly increased high density lipoprotein (HDL) cholesterol and the HDL-serum cholesterol ratio and lowered the very low density lipoprotein (VLDL) triglycerides. Thus the lipoprotein pattern was comparable to that obtained with the low fat diet, but the VLDL lipid composition remained altered. At the same time, triglyceride and cholesterol accumulation in the liver and the triglyceride content in skin were significantly decreased. When wheat germ was added to the low fat diet, cholesterol and triglycerides were not significantly modified. No adaptative change in lipase and colipase contents was observed in the pancreas of rats fed the wheat germ-supplemented diets, whereas the high fat diet increased these values. The results show a beneficial effect of wheat germ added to a high fat-cholesterol diet on the lipid status of rats; the implicated mechanisms are yet to be elucidated.

Animals↗

Human calcium absorption from whole-wheat products.

Fractional calcium absorption from wheat products and the influence of co-ingested wheat products on calcium absorption from milk were measured in a series of randomized crossover studies in healthy adult women. The wheat had been intrinsically labeled with 45Ca during growth. In the first study, fractional calcium absorption from leavened whole-wheat bread averaged 0.817 +/- 0.124. By comparison, absorption from milk, ingested at a comparable load in the same women, averaged only 0.589 +/- 0.111. When labeled bread was co-ingested with milk, at the same aggregate load as for bread alone, bread calcium absorption fell to 0.748 +/- 0.103 (P less than 0.05). In a second study, calcium absorption from an extruded cereal prepared from intrinsically labeled wheat bran was compared with milk. Calcium absorption from the cereal (0.223 +/- 0.046) was significantly less than from milk (0.375 +/- 0.072) (P less than 0.001). When the two were co-fed at the same total load, milk calcium absorption fell to 0.258 +/- 0.055 (P less than 0.001). In a third study, the effect of phytate hydrolysis through yeast fermentation and of Maillard browning on calcium absorption was investigated using leavened bread and underbaked and overbaked cookies, each made with intrinsically labeled wheat flour. Calcium absorption from cookies was not affected by the extent of browning and averaged 0.652 +/- 0.087. However, calcium absorption from bread in these same women averaged 0.703 +/- 0.108. This was significantly more than from the cookies (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Whole wheat and triticale flours with differing viscosities stimulate cecal fermentations and lower plasma and hepatic lipids in rats.

Whole flours from oat, rye or barley effectively modify digestive fermentation and lipid metabolism, whereas the effectiveness of whole wheat flour has not been established. To address this question, cecal digestion, short-chain fatty acid (SCFA) metabolism and cholesterol metabolism were investigated in four groups of rats fed the following semipurified diets differing in their carbohydrate source: a control diet (purified wheat starch) and three whole cereal flour diets [Valoris wheat (Wv), Soissons wheat (Ws), or Carnac triticale (Tc)]. Wv is particularly viscous and rich in arabinoxylans, and Tc is richer in hemicellulose than wheat. Compared with controls, rats fed the whole-flour diets had enlarged ceca and a moderate acidification of the bulk pH ( approximately 6.4). In these rats, the cecal SCFA pool size was enhanced (P < 0.05), and the SCFA molar ratio reflected propionic/butyric acid-rich fermentations, especially in those fed TC: The portal SCFA concentrations reflected the rise of the acetic and propionic acid pools in the cecum, whereas portal butyric acid remained relatively low, probably reflecting extensive metabolism by the cecal wall. The fecal excretion of total steroids (bile acids + sterols) was markedly enhanced by all of the whole-flour diets, with Wv (+78%) > Tc (+64%) > Ws (+47%). In parallel, there was a significant plasma cholesterol-lowering effect for rats fed Wv (-27%) and Tc (-32%) and a plasma triglyceride-lowering effect (approximately -40%) in all rats fed whole-flour diets (P < 0.05). This effect was observed mainly for triglyceride-rich lipoprotein-cholesterol, whereas HDL cholesterol was unaffected. These results indicate that whole wheat flours can strikingly affect cecal SCFA, especially butyrate, and are effective plasma cholesterol-lowering agents.

Animals↗

Iron bioavailability and utilization in rats are lower from lime-treated corn flour than from wheat flour when they are fortified with different sources of iron.

Although iron bioavailability from wheat flour fortified with iron has been widely studied, the bioavailability of lime-treated corn flour has not been evaluated sufficiently. We compared iron bioavailability and utilization of lime-treated corn flour and wheat flour supplemented with various iron sources. Bioavailability and utilization were determined in Sprague-Dawley rats using the iron balance and hemoglobin depletion-repletion methods. Rats were iron depleted by feeding them a low iron, casein diet for 10 d. During the repletion period, the rats were fed diets based on lime-treated corn flour or wheat flour, both supplemented with ferrous fumarate, ferrous sulfate, ferric citrate and reduced iron for 14 d. Hemoglobin was determined at the end of depletion and repletion periods. The phytate concentration was lower in wheat flour (114 mg/100g) than in lime-treated corn flour (501 mg/100g). Iron bioavailability and utilization by rats were higher from fortified and unfortified wheat flour than from the lime-treated corn flour counterparts. Iron utilization was greater in rats fed wheat flour supplemented with ferrous sulfate, followed by fumarate and citrate than in rats fed reduced iron. In lime-treated corn flour, iron utilization by rats fed unfortified flour and flour fortified with reduced iron did not differ, but utilization was higher in rats fed corn flour fortified with iron sulfate, fumarate and citrate than with reduced iron. We conclude that fortification of lime-treated corn flour with reduced iron has no effect on iron bioavailability or utilization, probably due to the high phytate content. Other iron compounds must be selected to fortify lime-treated corn flour when intended for public nutrition programs.

Animals↗

Whole-grain rye bread consumption by women correlates with plasma alkylresorcinols and increases their concentration compared with low-fiber wheat bread.

Whole-grain rye and wheat products are rich in lignans, the precursors of enterolactone (ENL) and alkylresorcinols (ARs), which are phenolic lipids. In this crossover trial, we examined the effect of whole-grain rye bread compared with low-fiber wheat bread on plasma AR levels. Women (n = 39) aged 59 +/- 0.94 y (mean +/- SEM) were advised to consume rye (214 +/- 7.1 g/d) or wheat (178 +/- 6.5 g/d) bread (20% of total daily energy intake) in random order for 8 wk. The test periods were separated by an 8-wk washout period. ARs with different homologues and ENL were measured in plasma collected at the beginning (habitual diet) and end of the test bread periods. AR concentrations were higher (P < 0.001) after the rye bread (352 +/- 24.7 nmol/L) and habitual diet (97.7 +/- 12.1 and 88.3 +/- 8.7 nmol/L) periods than after the wheat bread period (36.6 +/- 4.2 nmol/L). Plasma AR concentrations were correlated with intake of rye bread (r = 0.34, P = 0.037), and with insoluble fiber from the whole diet during the rye (r = 0.39, P = 0.013) and wheat (r = 0.32, P = 0.047) bread periods. The plasma AR 17:0/21:0 ratio differed after the rye (0.84 +/- 0.04) and wheat (0.53 +/- 0.08) bread diet periods (P < 0.001). These data strongly suggest that plasma ARs could be used as specific biomarkers for whole-grain rye intake, and their homologue pattern could be used as an indicator of the bread type consumed.

Bread↗

Chloroplast-like transfer RNA genes expressed in wheat mitochondria.

In the course of a systematic survey of wheat mitochondrial tRNA genes, we have sequenced chloroplast-like serine (trnS-GGA), phenylalanine (trnF-GAA) and cysteine (trnC-GCA) tRNA genes and their flanking regions. These genes are remnants of 'promiscuous' chloroplast DNA that has been incorporated into wheat mtDNA in the course of its evolution. Each gene differs by one or a few nucleotides from the authentic chloroplast homolog previously characterized in wheat or other plants, and each could potentially encode a functional tRNA whose secondary structure shows no deviations from the generalized model. To determine whether these chloroplast-like tRNA genes are actually expressed, wheat mitochondrial tRNAs were resolved by a series of polyacrylamide gel electrophoreses, after being specifically end-labeled in vitro by 3'-CCA addition mediated by wheat tRNA nucleotidyltransferase. Subsequent direct RNA sequence analysis identified prominent tRNA species corresponding to the mitochondrial and not the chloroplast trnS, trnF and trnC genes. This analysis also revealed chloroplast-like elongator methionine, asparagine and tryptophan tRNAs. Our results suggest that at least some chloroplast-like tRNA genes in wheat mtDNA are transcribed, with transcripts undergoing processing, post-transcriptional modification and 3'-CCA addition, to produce mature tRNAs that may participate in mitochondrial protein synthesis.

Base Sequence↗

Aspartate and asparagine tRNA genes in wheat mitochondrial DNA: a cautionary note on the isolation of tRNA genes from plants.

We have identified genes encoding a "native" tRNA(Asp) (trnD-GTC) and a "chloroplast-like" tRNA(Asn) (trnN-GTT) on opposite strands and 633 bp apart within a sequenced 1640 bp RsaI restriction fragment of wheat mtDNA. The trnD gene has been found previously at a different location in wheat mtDNA (P.B.M. Joyce et al. (1988) Piant Mol. Biol. 11, 833-843); the duplicate copies of this gene are identical within the coding and immediate flanking regions (9 bp downstream and at least 68 bp upstream), after which obvious sequence similarity abruptly disappears. The trnN gene is identical to its homolog in maize ctDNA; continuation of sequence similarity beyond the coding region suggests that this gene originated as promiscuous ctDNA that is now part of the wheat mitochondrial genome. In the course of this work, we have encountered some unexpected similarities between tRNA gene regions from wheat mitochondria and other sources. Detailed analysis of these similarities leads us to suggest that trnN genes reportedly from petunia nuclear DNA (N. Bawnik et al. (1983) Nucleic Acids Res. 11, 1117-1122) and lupine mtDNA (B. Karpińska and H. Augustyniak (1988) Nucleic Acids Res. 16, 6239) are, in fact, from petunia mtDNA and lupine ctDNA, respectively, whereas a putative wheat nuclear tRNA(Ser) (trnS-TGA) gene (Z. Szwekowska-Kulińska et al. (1989) Gene 77, 163-167) is actually from wheat mtDNA. In these instances, it seems probable that the DNA samples used for cloning contained trace amounts of DNA from another sub-cellular compartment, leading to the inadvertent selection of spurious clones.

Base Sequence↗

Further biochemical characterization of wheat DNA primase: possible functional implication of copurification with DNA polymerase A.

DNA primase has been partially purified from wheat germ. This enzyme, like DNA primases characterized from many procaryotic and eucaryotic sources, catalyses the synthesis of primers involved in DNA replication. However, the wheat enzyme differs from animal DNA primase in that it is found partially associated with a DNA polymerase which differs greatly from DNA polymerase alpha. Moreover, the only wheat DNA polymerase able to initiate on a natural or synthetic RNA primer is DNA polymerase A. In this report we describe in greater detail the chromatographic behaviour of wheat DNA primase and its copurification with DNA polymerase A. Some biochemical properties of wheat DNA primase such as pH optimum, Mn + 2 or Mg + 2 optima, and temperature optimum have been determined. The enzyme is strongly inhibited by KCI, cordycepine triphosphate and dATP, and to a lesser extent by cAMP and formycine triphosphate. The primase product reaction is resistant to DNAse digestion and sensitive to RNAse digestion. Primase catalyses primer synthesis on M13 ssDNA as template allowing E.coli DNA polymerase I to replicate the primed M13 single-stranded DNA leading to double-stranded M13 DNA (RF). M13 replication experiments were performed with wheat DNA polymerases A, B, CI and CII purified in our laboratory. Only DNA polymerase A is able to recognize RNA-primed M13 ssDNA.

Chromatography, DEAE-Cellulose↗

Organization and expression of the mitochondrial genome of plants I. The genes for wheat mitochondrial ribosomal and transfer RNA: evidence for an unusual arrangement.

We show here that mitochondrial-specific ribosomal and transfer RNAs of wheat (Triticum vulgare Vill. [Triticum aestivum L.] var. Thatcher) are encoded by the mitochondrial DNA (mtDNA). Individual wheat mitochondrial rRNA species (26S, 18S, 5S) each hybridized with several mtDNA fragments in a particular restriction digest (Eco RI, Xho I, or Sal I). In each case, the DNA fragments to which 18S and 5S rRNAs hybridized were the same, but different from those to which 26S rRNA hybridized. From these results, we conclude that the structural genes for wheat mitochondrial 18S and 5S rRNAs are closely linked, but are physically distant from the genes for wheat mitochondrial 26S rRNA. This arrangement of rRNA genes is clearly different from that in prokaryotes and chloroplasts, where 23S, 16S and 5S rRNA genes are closely linked, even though wheat mitochondrial 18S rRNA has previously been shown to be prokaryotic in nature. The mixed population of wheat mitochondrial 4S RNAs (tRNAs) hybridized with many large restriction fragments, indicating that the tRNA genes are broadly distributed throughout the mitochondrial genome, with some apparent clustering in regions containing 18S and 5S rRNA genes.

DNA Restriction Enzymes↗