Intact Grains Research Articles

Flavonol 3-O-glycosyltransferases associated with petunia pollen produce gametophyte-specific flavonol diglycosides.

Wild-type petunia pollen accumulates high levels of flavonol 3-O-glycosides. Pollen from conditionally male-fertile petunia has no flavonols and is unable to germinate. Pollen function is restored both in vivo and in vitro by providing flavonol aglycones, but not flavonol glycosides, to the pollen. In the present study, incubation of an in vitro suspension of conditionally male-fertile pollen with kaempferol or quercetin resulted in the accumulation of kaempferol and quercetin 3-O-glycosides in the pollen. We identified two glycosyltransferase activities associated with the intact pollen grain that catalyze the formation of a gametophyte-specific class of flavonol glycosides. Feeding studies showed that product formation was highly specific for flavonols with an unsubstituted 3-hydroxyl group and was not dependent on an external source of UDP-hexose. Ultraviolet spectral analysis, fast atom bombardment mass spectrometry, 1H-nuclear magnetic resonance, and 13C-nuclear magnetic resonance identified the products as kaempferol and quercetin 3-O-(2"- O-beta-D-glucopyranosyl)-beta-D-galactopyranoside, identical with the flavonol 3-O-glycosides present in wild-type pollen. The sugars are linked in a 1-->2 configuration that results in a pollen-specific class of compounds. To retain both glycosyltransferase activities in a cell-free extract, it was necessary to add triton X-100, suggesting that one or both of the proteins may be associated with a pollen membrane. A model for flavonol glycoside biosynthesis and uptake into the pollen is discussed in terms of the germination requirement for flavonols.

Influence of potassium nutrition on germinability, abscisic acid content and sensitivity of the embryo to abscisic acid in developing seeds of Sorghum bicolor (L.) Moench

summaryPre‐harvest sprouting in maturing seeds of Sorghum bicolor (L.) Moench is a major problem in the cultivation of this crop plant. The influence of potassium nutrition on germinability, abscisic acid (ABA) content and embryo ABA sensitivity in its developing seeds was investigated. Plants were grown in sand culture under three different potassium treatments: K1 (control), K2 (one third of the control potassium supply), and K3 (one ninth of the control potassium supply). Reduced potassium increased the germinability of developing seeds during the late stages of maturation (31 and 36 days after pollination, DAP), particularly in K2 grains. These changes in seed germinability were paralleled by a reduced ABA content in the seed and by a lower embryonic sensitivity to ABA. The ABA content of K2 intact grains peaked at 25 DAP and then decreased sharply, being 30–50% lower than that in the controls at 31 and 36 DAP. ABA content in the control gains peaked later in the developmental period (at 31 DAP). By contrast K3 grains had a remarkably constant ABA content during most of the developmental period (20–36 DAP). Sensitivity to ABA was markedly reduced in the embryos from both the low potassium treatments, particularly when tested at an ABA concentration of 5μM. The data indicate that potassium supply influences germinability, ABA concentrations and embryo ABA sensitivity in developing seeds in this species.

Aerodynamic size distribution of the particles emitted from the flowers of allergologically important plants

Abstract The existence of small particles emitted from the dehiscing anther at the time of pollen shedding is shown. We examined pollen samples of five plants causing pollinosis in Japan: Cryptomeria japonica, Alnus japonica, Quercus serrata, Dactylis glomerata and Ambrosia elatior. The pollen samples of C. japonica collected by hydroponic culture had two kinds of particles. The size of these particles was 0.46 to 1.4 μm and 29 to 40 μm (pollen grains) in diameter. The number of the small particles was about 8-fold greater than that of intact pollen grains. Alnus japonica, Quercus serrata and Dactylis glomerata also discharge small particles other than pollen grains although the number is not so large as Cryptomeria japonica. We could not recognize any small particles in a pollen sample of Ambrosia elatior.

Dust Around Young Stars: How Related to Solar System Dust?

Study of the dust in circumstellar disks around young stars is currently an extremely active area in astronomy. There is little doubt that accretion disks are a natural part of protostellar evolution. Much recent observational and theoretical work is giving us a clearer picture of the physical conditions in dust disks and their evolutionary progression. IRAS observations revealed that many main-sequence stars, such as p Pictoris, have circumstellar disks. But whether these disks are related to planetary formation is not yet understood.A portion of the dust in disks around young stars ultimately may be incorporated into planetary systems. Thus, study of the dust in our own solar system complements the remote sensing of protostellar regions and aids in reconstructing the evolutionary history of the dust. Since comets formed in the cold outer regions of the solar nebula, they may contain intact interstellar grains. As the comets lose material during passage through the warm inner solar system, some of these grains will be released into interplanetary space. Technical advances now allow analysis of individual micrometer or smaller grains in interplanetary dust particles and primitive meteorite samples. Isotopic anomalies and patterns of crystal growth in these particles are yielding tantalizing clues about the interstellar material incorporated into these solar system samples.

Whole grains--impact of consuming whole grains on physiological effects of dietary fiber and starch.

Much of the present research on the physiological effects of dietary fiber and starch has been done on sources isolated from the parent material, and it is not clear whether they have the same effects if fed in the intact or whole grain. For dietary fiber, physiological effect depends on extent of fermentation in the large intestine, and this is influenced by chemical composition, solubility, physical form, and presence of lignin or other compounds. All of these factors are altered by isolation of a fiber source from the whole grain, and hence effects of eating fiber vary. Similarly, physical form and presence in the whole grain will affect digestibility of starch in the small intestine, which in turn influences the glycemic response and colonic effects determined by the extent of malabsorption and entry into the colon. Starch that enters the colon is fermented and produces short-chain fatty acids, particularly butyrate, which is necessary to maintain a healthy mucosa. Hence, their presence within the whole grain may have important implications for health for both dietary fiber and starch. Evidence indicates that such effects are beneficial and that whole-grain consumption should be encouraged.

Variations in airborne pollen antigenic particles caused by meteorologic factors.

High birch pollen antigenic activities in outdoor air samples were found in all particle sizes studied (> 7.2, 2.4-7.2, < 2.4 microns and molecular size class, with an ELISA modification). Sampling was done with a low-volume, size-selective bioaerosol sampler (SSBAS) simulating the human respiratory tract in both volume and fractionation. Airborne birch pollen counts for comparisons were obtained from a Burkard trap. No correlations were obtained between antigen concentrations in any particle size fraction and airborne pollen counts. The meteorologic factors studied differed clearly in their effect on antigenicity, depending on the size class studied. Likewise, the effect of meteorologic factors differed among the three study periods (period I, 4 weeks before the peak pollen season; period II, during the season; and period III, 4 weeks after the season). During the peak pollen period, temperature and relative humidity were the most important meteorologic factors. Before the season, large and very small particles predominated, medium-sized particles being totally absent. The largest size class studied (containing all intact pollen grains) clearly reacted to changes in meteorologic factors; for smaller size classes, these factors were found to be less important, a fact which may make the forecasting of antigen concentrations in the air on the basis of meteorologic data impossible.

Airborne birch pollen antigens in different particle sizes

Two particle samplers for ambient air, situated together: a static size-selective bio-aerosol sampler (SSBAS) and a Burkard pollen and spore trap were compared in sampling intact birch pollen grains through one flowering period of Betula (a total of 44 days). The SSBAS trapped pollen grains three times more efficiently than the Burkard trap, but the variations in pollen counts were significantly correlated. In contrast, birch pollen antigenic activity and the pollen count in the Burkard samples were not closely correlated. The antigenic concentration was occasionally high both before and after the pollination period. There was a high birch pollen antigenic activity in particle size classes where intact pollen grains were absent, even on days when the pollen count was very low. Correspondingly, on days with high birch pollen counts in the air, pollen antigenic activity was on several occasions low, indicating that pollen grains were empty of antigenic material. The small particle size classes are especially important to allergic patients because they are able to penetrate immediately into the alveoli and provoke asthmatic reactions. Therefore, aerobiological information systems based on pollen and spore counts should be supplemented with information concerning antigenic activities in the air.

Random models for morphological analysis of powders

SummaryModels to estimate powder size distributions or fractions of components in a mixture of powders were developed and tested for various specimens. The models derived from the Boolean model and from the dead leaves models can be implemented on rough secondary electron scanning electron microscope images, obtained after minimal sample preparation. With the dead leaves tessellation, the size distributions of spherical particles or short fibres can be estimated either from the size distribution of intact grains, or from the area fraction measurement after binary erosions. With the dead leaves random function, there is no need for image segmentation. It provides data on the size and shape of a population of particles from an estimation of the distribution of grey‐level images after erosions by convex structuring elements of increasing size. A version of these models for long fibres is developed for estimating their diameter distribution. Allowing for superposition of particles, the proposed methods enable an unbiased estimation of the size distribution and characterization of the shape of complex particles. The approach is illustrated by applications to spherical particles obtained by simulations and from scanning electron microscope micrographs.

Development and regulation of (1→3,1→4)-β-glucan endohydrolases in germinating wheat (Triticum aestivum)

AbstractThe development of (1→3,1→4)-β-glucan 4-glucanohydrolase (EC 3.2.1.73) has been examined in germinating wheat (Triticum aestivum cv. Millewa) grain, and in isolated aleurone layers and scutella. Activity is first detected in extracts of intact grain 2–3 days after the initiation of germination and thereafter increases until 6 days. In isolated aleurone layers, (1→3,1→4)-β-glucanase activity is secreted for up to 4 days. Treatment of aleurone layers with gibberellic acid (GA3) results in a 2-fold enhancement of secreted enzyme for the first 2 days, but activity decreases after 2 days. (1→3,1→4)-β-Glucanase secretion from GA3-treated aleurone layers clearly precedes the secretion of amylase and (1→4)-β-xylanase. Small but significant levels of cellulase are secreted from aleurone layers after GA3 treatment. Isolated scutella also secrete (1→3,1→4)-β-glucanase but GA3 has little apparent effect on secretion patterns from this tissue. Proteins secreted from excised aleurone layers and scutella, together with those in homogenates of intact, germinated grain, have been examined by Western blot analysis, using monoclonal antibodies against barley (1→3,1→4)-β-glucanases as probes. In each case the wheat (1→3,1→4)-β-glucanase is recognised only by the monoclonal antibody that is specific for barley isoenzyme El.

Properties of Tree and Grass Pollen Allergens: Reinvestigation of the Linkage between Solubility and Allergenicity

In this study we reinvestigated the kinetics of allergen release from birch pollen (Betula verrucosa) and timothy grass pollen (Phleum pratense) using different protein extraction procedures, immunoblotting with specific antibodies and immune electron microscopy. Pollen allergens such as the major birch pollen allergen, Bet v I, the major timothy grass pollen allergens, Phl p I and Phl p V, group-II/III allergens from timothy grass and profilins were released rapidly and in large amounts from hydrated pollen. Within a few minutes pollen allergens could be detected in aqueous supernatants prepared from birch and grass pollen with serum IgE or specific antibodies. In parallel the allergen content in the pollen pellet fractions decreased. A nonallergenic protein such as heat shock protein 70 can be extracted in sufficient amounts only with harsh extraction procedures. Immune electron microscopy of dry and rehydrated birch pollens showed that after short hydration, the major birch pollen allergen, Bet v I, migrated into the exine and to the surface of intact pollen grains, whereas profilin, against which a lower percentage of patients is sensitized, was retained in the pollen grain. Comparing the amino acid composition and hydrophilicity of the tested allergens with a nonallergenic protein such as heat shock protein 70, no significant difference was noted. In agreement with earlier observations we conclude that the allergenic properties of proteins are rather linked to the amount and speed of solubility from airborne particles than to intrinsic properties.

Isolation of Allium pollen protoplasts

Studies on protoplasts isolation were carried out with mature pollen grains of 29 samples of species of Allium aflatunense, A. cepa, A. fistulosum, A. karataviense, A. longicuspis, A. nutans, A. odorum, A. sativum and A. schoenoprasum. Surface sterilized pollen grains drifted from crushed anthers were incubated in an enzyme solution containing 1% (w/v) cellulase Onozuka R-10, 1% (w/v) Macerozyme R-10, 0,5 mol l-1 sucrose and the basal salts of Nitsch medium. Protoplasts were released within 3 to 120 min, either from the pollen grain, through a slightly disturbed germination pore (narrow aperture), or through a wider aperture, when the exine surrounding the germination pore was disturbed. For the first time, protoplasts were obtained from 13 genotypes of 6 Allium species, at a rate of 1 to 30% of the digested intact pollen grains, depending on the genotype.

Effect of processing barley and wheat grain on the digestion of silage-based diets by breeding ewes

AbstractFifty-six individually penned pregnant ewes were offered silage ad libitum with wheat or barley in a replicated experiment. Each of these cereals was either unprocessed or processed by rolling or milling and was offered at 300 g/day from 6 weeks before lambing and at 600 g/day from 3 weeks before lambing. Five and 2 weeks before lambing, total faeces were collected over 6-day periods. On average proportionately 0·18 of the unprocessed wheat and 0·20 of the unprocessed barley consumed was recovered as intact grain in the faeces. Mean digestibility of the organic matter in the complete diet increased from 726 g/kg on whole to 748 g/kg on rolled and 759 g/kg on milled cereal (P &lt; 0·01) at the 300 g/day level and from 721 g/kg on whole to 766 g/kg on rolled and 772 g/kg on milled cereals (P &lt; 0·001) at the 600 g/day level. When the effect of egested whole grain was removed there was no evidence of an effect of cereal processing on organic matter digestibility and although digestibility of fibre was higher with whole than with processed grain the effect was not significant. Wheat-based diets were more digestible than barley-based diets and, compared with barley, wheat appeared to have a beneficial effect on fibre digestion.

Effect of Sucrose on Phase Behavior of Membranes in Intact Pollen of Typha latifolia L., as Measured with Fourier Transform Infrared Spectroscopy

In previous studies, we have shown that the temperature dependent vibrational frequency of the CH(2) stretch in hydrocarbons in intact pollen grains can be recorded with Fourier transform infrared spectroscopy and used to measure phase transition temperatures (T(m)) in these hydrocarbons. Circumstantial evidence was provided that the major contribution to the signal seen in these samples was from membrane phospholipids, and that sucrose in the dry pollen grains reduced T(m) of those phospholipids. In the current study, we clarify why a major constituent of the pollen grains, neutral lipids contained in discrete lipid droplets, does not contribute significantly to the signal. Further, we have isolated membranes from the pollen and show that T(m) in the isolated membranes rises from -6 degrees C in the hydrated membranes to 58 degrees C when the membranes are dried without the addition of sucrose. However, when the isolated membranes are dried in the presence of increasing amounts of sucrose, T(m) fell steadily, reaching a minimal value of 31 degrees C, a figure in good agreement with that seen in the intact pollen grains. The amount of sucrose required to depress T(m) maximally in these membranes is also apparently in agreement with that found in the intact pollen, suggesting that sucrose depresses T(m) in the pollen.

Existence of exine‐free airborne allergen particles of Japanese cedar (Cryptomeria japonica) pollen

We investigated whether exine-free pollen allergen particles exist together with the intact pollen grains of Japanese cedar (Cryptomeria japonica) in the air during the pollen season in Yamagata City. First, we separated the allergen particles in an Andersen multi-stage air-sampler according to their aerodynamic diameters. The amount of major allergen (Cry j I) on each stage of the sampler was determined by a sensitive fluorometric sandwich ELISA, and the pollen count of the same samples was done by light microscopy after Carberla staining. Cry j I was found in stages 1 to 6, whereas most of intact and ruptured pollen grains were microscopically observed only in stages 1 and 2. Second, we suctioned the air through a tandem membrane filter system (the first filter, Nuclepore filter with 5 microns-pores; and the second, Millipore filter with 0.3 micron-pores). None of the pollen grains was detectable on the 0.3 micron-pore filter with light microscopy. However, Cry j I was detectable in the aqueous extract from the second filter. From these results, we concluded that pollen-free Cry j I existed in the air of Yamagata City during the pollen season.

Temperature changes in lipid and protein structure measured by fourier transform infrared spectrophotometry in intact pollen grains

Fourier Transform infrared (FTIR) spectroscopy was used to monitor structural changes in lipids and proteins in four species of pollen grains at different temperatures. Spectral data were used to determine membrane phase transition temperature ( Tm) in pollen at two hydration levels. Imbibition was conducted at temperatures above and below the determined Tm values to correlate damage to the presence of gel phase. For three species of pollen, hydration overcame imbibitional damage at low temperature. However, dry pecan pollen, which had a high lipid content, was injured during imbibition at temperatures above and below the Tm. Changes in protein structure were not related to imbibitional damage. FTIR spectroscopy is a useful tool in examining biochemical properties of intact pollen grains and has potential for evaluating cryopreservation protocols.

Fracture toughness and crack bridging of a silicon nitride ceramic

Toughening processes and mechanisms of a gaspressure-sintered silicon nitride ceramic with ß-phase rod-like microstructure are studied by the quantitative measurement of the R-curve in the form of the crack growth resistance, K R , versus the crack extension, Δa, K R being 4·3 M Pam 1 2 at crack initiation and then increasing to 6·5 M Pam 1 2 for its plateau value after a crack extension of about 1 mm. It is concluded that the toughness improvement of silicon nitride ceramics with rod-like microstructure arises from the crack bridging of the intact grains, but not from the crack-tip deflection and bowing processes which have been believed to date to be the key microfracture processes for toughening silicon nitride ceramics with ample rod-like ß-phase grains. An gasdruckgesintertem Si 3 N 4 mit einem Gefüge aus stäbchenförmigem ß-Si 3 N 4 wurden durch quantitative Auswertung der R-Kurve wirkende Verstärkungs-mechanismen untersucht. Dabei wurde der Rißwiderstand, K R , über der Rißverlängerung, Δa, aufgetragen. Zu Beginn betrug der K R -Wert 4·3 M Pam 1 2 und stieg nach einer Rißausbreitung von circa 1 mm auf seinen Endwert von 6·5 M Pam 1 2 . Die Ergebnisse zeigen, daß die Zähigkeitssteigerung in Si 3 N 4 -Keramik mit stäbchenförmigem Gefüge auf eine Rißüberbrückung intakter Körner zurückzuführen ist. Dies widerspricht der bisherigen Annahme, die Zähigkeitssteigerung in Si 3 N 4 -Keramik mit ß-Si 3 N 4 -Anteil durch durch eine Ablenkung an der Riß-spitze oder einen Durchbiegungsprozeß zu erklären. Nous avons étudié les mécanismes de renforcement d'une céramique de nitrure de silicium fabriquée par frittage sous pression de gaz, et caractérisée par la présence de gros cristaux aciculaires de ß-Si 3 N 4 en son sein. La mesure quantitative de la courbe R, montrant l'évolution du paramètre de résistance à la propagation des fissures, K R , en fonction de l'extension de la fissure, Δa, nous a permis de relever une valeur à l'initiation de 4·3 M Pam 1 2 , et une valeur plateau de 6·5 M Pam 1 2 , atteinte après une croissance de 1 mm. Nous avons conclu que le renforcement des céramiques de nitrure de silicium à gros cristaux aciculaires est dû au pontage de la fissure par ces grains, et non pas à des phénomènes de déflection du front de fissure, qui jusqu' à présent étaient considérés comme le paramètre clé conduisant au renforcement des ceramiques de nitrure de silicium à gros cristaux de ß-Si 3 N 4 .

Fracture of concrete under multiaxial stress-recent developments

The paper reviews the influence of structural effects on the softening of concrete in multiaxial compression. The post-peak stress-deformation response of concrete subjected to uni- and multiaxial compression is influenced by geometrical and boundary condition effects. Comparison of results obtained by various investigators indicates that fracture in compression is a localized phenomenon. Conical intact material elements are separated by discrete shear bands. Structural effects determine the movement of the intact blocks with respect to one another. Material aspects of softening include the appearance of intact (grain) bridges in the shear bands, and frictional restraint in the shear band. The similarities with fracture in uniaxial tension are outlined. In the latter case crack interface grain bridging is observed too, which is considered as the salient characteristic of the fracture of brittle disordered materials.

Effect of forage type on the digestion of whole barley grain by breeding ewes

ABSTRACTThe proportion of whole grain consumed that was voided intact in the faeces of ewes in late pregnancy and early lactation was measured for diets based on a range of forages in two experiments. The proportions of grain voided intact varied widely between ewes and was to some extent a characteristic of the individual ewe. During late pregnancy on hay-based diets the mean proportion of grain recovered was 0·053 with a range from 0·042 to 0·063 while on silage-based diets 0·135 (range 0·082 to 0·209) was recovered. On silage-based diets after lambing 0·196 and 0·235 of grain was voided intact in the faeces. The proportion of intact grain voided was affected by forage intake. The estimated increase in the proportion of grain voided intact was 0·012 measured over a range of forages before lambing and 0·021 on silage after lambing per 100 g increase in dry matter intake. However, when the total digestibility was measured, there were no differences between feeding of whole and processed grain where proportionately 0·06 of whole grain consumed was voided intact.

Ultrastructure of egg apparatus of rice (Oryza sativa) after anthesis.

A light and transmission electron microscope study was made on the disposition of an egg cell and two synergids in Oryza sativa ovules. After anthesis, one of the synergids is rather persistent while the other is degenerating with collapse of the plasma membrane and penetration of ground plasma into the space between the plasma membranes of the egg cell and the central cell. Spherical vesicles in degenerating synergids closely resemble polysaccharide particles in intact pollen grains. Singular cisternae in the central cells tightly associate with the plasma membrane which borders on the degenerating synergids. There are osmiophilic deposits in the narrow interspace between the plasma membranes of the egg cell and the persistent synergid or the central cell. The egg cell has a nucleus with two nucleoli. The persistent synergid has a malformed nucleus forced on a pocket portion of central cell. The portion is occupied by a large number of cell wall ingrowths. It is postulated from the cyto-histological features of ovaries that nutrition into the egg cells is supplied through transmembranal, symplastic and apoplastic routes.

Chapter 27 Aerobiology of pollen and fungal allergens

Clinically important pollinosis is primarily due to flowering plants with wind-dispersed pollens. Although these anemophilous species form a minority of flowering plants, they produce prodigious amounts of pollen. Entemophilous (insect-pollinated) plants produce relatively few pollen grains. Plants having only a portion of their pollen grains airborne are termed amphiphilous. Their role in pollinosis is not clear. The pollen-producing organs, stamens, consist of an anther attached to a filament. Allergenic pollens develop in and are released from pollen sacs contained in the anthers. Pollen sacs are lined with a nutritive cell layer, the tapetum. During its formation, each immature pollen grain secretes about itself a clear layer, the intine. Around this the tapetum deposits a multilayer exine composed of a polymer, sporopollenin. Release of pollen from the anther is known as anthesis. Drying creates gaps in the anther wall through which pollen escapes. Airborne pollen levels tend to increase during warm, dry, clear conditions and fall during cool, moist periods. Although pollen grains can travel several hundred miles, concentrations of windbome pollens generally decrease sharply within a few hundred meters of their source. Intact pollen grains are presumed to be the primary carriers of allergen, but ragweed allergens have been associated with particles <5 km, and Amb a I (antigen E) activity has been found in submicronic particles. Pollen allergens can be extracted from the somatic portion of ragweed plants and may become airborne in vegetable debris. Furthermore, allergens might be eluted from pollen grains deposited on moist surfaces, with dispersion of the resultant extract in droplets. Air sampling relies on recovery of pollen grains for microscopic evaluation. The gravity (Durham) sampler uses greased microslides for pollen collection. This obsolete device is limited by uncertainty in the volume of air sampled and a tendency to