Outer Tissue Research Articles

Repair of rabbit radius defect by using recombinant of hBMP2/hVEGF165 modified BMSCs with porous nano-hydroxyapatite/polyamide 66 composite

Objective To assess the effect of bone defect repair using the recombinant of adenovirus-mediated hBMP2 and hVEGF165 genes transfer of BMSCs with porous nano-hydroxyapatite/polyamide 66 (n-HA/PA66). Methods Sixty male adult New Zealand rabbits were assigned to groups A, B and C according the completely random design, with 20 rabbits per group. Bone defect of 15 mm in length was made in the middle segment of bilateral radii in rabbits. In Group A, the defects were filled with nothing on the left side in blank controls (Group A1) and with n-HA/PA66 material alone on the right side (Group A2). In Group B, the defects were filled with hVEGF165/BMSCs/n-HA/PA66 on the left side (Group B1) and hBMP2/ BMSCs/n-HA/PA66 on the right side (Group B2). In Group C, the defects were filled with BMSCs/n-HA/PA66 on the left side (Group C1) and hBMP2/hVEGF165/BMSCs/n-HA/PA66 on the right side (Group C2). Radiological analysis, HE staining, and Masson coloration were performed 2, 4, 8 and 12 weeks after operation. Results Radiographs, HE staining and Masson staining taken 8 weeks after cell transplantation showed large amount of new cartilage grown into the defect area and massive bony tissue formation around the margin in Group C2. At postoperative 12 weeks, Group C2 showed transplants were surrounded by outer bone tissues with superior bone repair effect to other groups (P 0.05). Conclusion hBMP2/hVEGF165 genes transferred BMSCs seeded on porous n-HA/PA66 can contribute to osteogenesis during the repair of rabbit radius defect. Key words: Bone morphogenetic proteins; Vascular endothelial growth factors; Bone defect

Endomembrane proteomics reveals putative enzymes involved in cell wall metabolism in wheat grain outer layers.

Cereal grain outer layers fulfil essential functions for the developing seed such as supplying energy and providing protection. In the food industry, the grain outer layers called 'the bran' is valuable since it is rich in dietary fibre and other beneficial nutriments. The outer layers comprise several tissues with a high content in cell wall material. The cell wall composition of the grain peripheral tissues was investigated with specific probes at a stage of active cell wall synthesis. Considerable wall diversity between cell types was revealed. To identify the cellular machinery involved in cell wall synthesis, a subcellular proteomic approach was used targeting the Golgi apparatus where most cell wall polysaccharides are synthesized. The tissues were dissected into outer pericarp and intermediate layers where 822 and 1304 proteins were identified respectively. Many carbohydrate-active enzymes were revealed: some in the two peripheral grain fractions, others only in one tissue. Several protein families specific to one fraction and with characterized homologs in other species might be related to the specific detection of a polysaccharide in a particular cell layer. This report provides new information on grain cell walls and its biosynthesis in the valuable outer tissues, which are poorly studied so far. A better understanding of the mechanisms controlling cell wall composition could help to improve several quality traits of cereal products (e.g. dietary fibre content, biomass conversion to biofuel).

StigmariaBrongniart: a new specimen from Duckmantian (Lower Pennsylvanian) Brymbo (Wrexham, North Wales) together with a review of known casts and how they were preserved

AbstractStigmariais one of the iconic plant fossils of the Carboniferous and fragments of the narrower parts of the rhizomorph are found in most museum collections. However, very few almost entire specimens have been found and preserved. A new specimen ofStigmariafrom Brymbo, North Wales is described and compared with other preserved examples from Europe and North America. The Brymbo specimen shows a large portion of trunk still attached to the large stigmarian base, which is a rare find, and this specimen supports our ideas of how these impressively large casts were formed. Stigmarias were preserved by the deposition of minerals around them following a sediment inundation, which gave sufficient support while the tissues rotted and filled with sediments. Remnants of the outer tissues were compressed to form a thin surrounding coal layer.

Structure, chemical composition and enzymatic activities of pearlings and bran obtained from pearled wheat (Triticum aestivum L.) by roller milling

While abrasive pearling (also referred to as debranning) of wheat kernels prior to milling increases the quality of the resultant flour for producing bread, the potential applications of the co-products of pearling is largely unknown. We studied the impact of different degrees of pearling (0, 3, 6, 9 and 12% by weight) on the composition of pearlings and bran obtained when subsequently roller milling pearled wheat kernels. Pearling does not remove the kernel outer tissues homogeneously as abrasion affects especially the accessible parts of the kernels. Nevertheless, the first 3% removed consisted of mainly pericarp. With 6% or more removed, a significant amount of starchy endosperm ended up in the pearlings. The starting bran material and bran obtained by subsequent roller milling of pearled wheat kernels had similar compositions but the latter had a lower average particle size. Moreover, removal of the outermost kernel layers substantially decreased the enzyme activity levels in the bran.

Translatome analyses capture of opposing tissue-specific brassinosteroid signals orchestrating root meristem differentiation

The mechanisms ensuring balanced growth remain a critical question in developmental biology. In plants, this balance relies on spatiotemporal integration of hormonal signaling pathways, but the understanding of the precise contribution of each hormone is just beginning to take form. Brassinosteroid (BR) hormone is shown here to have opposing effects on root meristem size, depending on its site of action. BR is demonstrated to both delay and promote onset of stem cell daughter differentiation, when acting in the outer tissue of the root meristem, the epidermis, and the innermost tissue, the stele, respectively. To understand the molecular basis of this phenomenon, a comprehensive spatiotemporal translatome mapping of Arabidopsis roots was performed. Analyses of wild type and mutants featuring different distributions of BR revealed autonomous, tissue-specific gene responses to BR, implying its contrasting tissue-dependent impact on growth. BR-induced genes were primarily detected in epidermal cells of the basal meristem zone and were enriched by auxin-related genes. In contrast, repressed BR genes prevailed in the stele of the apical meristem zone. Furthermore, auxin was found to mediate the growth-promoting impact of BR signaling originating in the epidermis, whereas BR signaling in the stele buffered this effect. We propose that context-specific BR activity and responses are oppositely interpreted at the organ level, ensuring coherent growth.

Effect of ranibizumab on high-speed indocyanine green angiography and minimum intensity projection optical coherence tomography findings in neovascular age-related macular degeneration.

The purpose of this 1-year prospective study was to investigate how induction/pro re nata ranibizumab intravitreal treatment of eyes with neovascular age-related macular degeneration affects the anatomy of choroidal neovascularization (CNV) and the overlying outer retinal tissue. High-speed indocyanine green (HS-ICG) angiography measurements provided quantification of the CNV size in 60 patients followed for 1 year. Minimum intensity projection optical coherence tomography (MinIP OCT), a novel algorithm assessing minimum optical intensity between the internal limiting membrane and retinal pigment epithelium, measured the area of outer retinal disruption overlying the CNV. Fluorescein angiography was also assessed to evaluate late retinal leakage. After 1 year, the mean area of CNV measured with indocyanine green angiography decreased by 5.8%. The mean area of MinIP OCT of outer retinal disruption overlying the CNV decreased by 4.2%. Mean area of fluorescein angiography leakage decreased by 6.3%. Both the area of outer retinal disruption measured with MinIP OCT and the area of leakage on fluorescein angiography typically exceeded the area of CNV on indocyanine green angiography at baseline and 1 year. Choroidal neovascularization treated with induction/pro re nata intravitreal ranibizumab for 1 year essentially remained static. Minimum intensity projection optical coherence tomography suggests that the area of outer retinal disruption overlying the CNV may be greater than the CNV itself and often correlates with the leakage area on fluorescein angiography. Additionally, there was minimal change in the area of outer retinal disruption on MinIP OCT even when fluid resolved. Measurements of the extent of CNV lesions based on indocyanine green angiography and MinIP OCT may provide useful outcome variables to help assess the CNV complex longitudinally and warrant further validation.

Multiscale stress-strain characterization of onion outer epidermal tissue in wet and dry states.

• Quantitative measurements of water's effects on the tension response of plant tissue will assist in understanding the regulatory mechanism underlying expansive growth. Such measurements should be multiscale in nature to account for plants' hierarchical structure.• Outer onion epidermal tissues were cut and bonded to uniaxial displacement-controlled mechanical loading devices to apply and measure the force on the sample. Fluorescent polystyrene beads (500 nm in diameter) were dispersed on the sample surface under various levels of tensile load conditions to obtain displacement maps with a confocal fluorescent microscope. The resulting strain was measured using a digital image correlation technique by tracking individual bead displacements. The applied forces were obtained by measuring the displacement of the calibrated force-sensing device. Tissue- and cell-scale mechanical properties were quantified by calculating the applied stress and the corresponding global and local strains.• The Young's modulus values of individual cell walls of dehydrated and rehydrated samples were 3.0 ± 1.0 GPa and 0.4 ± 0.2 GPa, respectively, and are different from the Young's modulus values of the global tissue-scale dehydrated and rehydrated samples, which were 1.9 ± 0.3 GPa and 0.08 ± 0.02 GPa, respectively. Poisson's ratio increased more than 3-fold due to hydration.• The results on global, cell-to-cell, and point-to-point mechanical property variations suggest the importance of the mechanical contribution of extracellular features including the middle lamella, cell shape, and dimension. This study shows that a multiscale investigation is essential for fundamental insights into the hierarchical deformation of biological systems.

Selective acceptance of Brassicaceous plants by the peach potato aphid Myzus persicae: a case study of Aurinia saxatilis

The probing behavior of Myzus persicae (Sulz.) was examined on the ornamental plant Aurinia saxatilis (L.) Desv. that has not been known as a host of M. persicaein nature, and compared to the behavior on cultivated plants of the genus brassica, B. rapa L. ssp. pekinensis L. and B . oleracea var. gongyloides, that are known hosts to this aphid. The purpose was to determine whether A. saxatilis can be exploited by M. persicaethus providing a potential refuge for the aphid population. The EPG (Elelctrical Penetration Graph) study demonstrated that on A. saxatilis, M. persicae showed mainly non-probing activities that occupied 70% of experimental time. The remaining time, which was probing, consisted mainly of pathway activities divided into numerous short probes not reaching beyond 1–2 cell layers and very few aphids reached phloem vessels. None aphid was able to ingest sap in a sustained way. In contrast, on bBassica plants, the probing of M. persicaewas rarely interrupted, all aphids reached sieve elements elements and ingested sap for long and uninterrupted periods. It is postulated that high content of glucosinolates in the outer tissues of A. saxatilis leaves may be responsible for the termination of M. persicae probing at the very early stage, thus preventing the contact with vascular elements and the ingestion of phloem sap. In consequence, A. saxatilisis rejected as a host plant by M. persicae.

Outer bark thickness decreases more with height on stems of fire-resistant than fire-sensitive Floridian oaks (Quercus spp.; Fagaceae).

• In ecosystems maintained by low-intensity surface fires, tree bark thickness is a determinant of fire-survival because it protects underlying tissues from heat damage. However, it has been unclear whether relatively thick bark i S: maintained at all heights or only near the ground where damage is most likely.• We studied six Quercus species from the red and white clades, with three species characteristic of fire-maintained savannas and three species characteristic of forests with infrequent fire. Inner and outer bark (secondary phloem and rhytidome, respectively) thicknesses were measured at intervals from 10 to 300 cm above the ground. We used linear mixed-effects models to test for relationships among height, habitat, and clade on relative thickness (stem proportion) of total, inner, and outer bark. Bark moisture and tissue density were measured for each species at 10 cm.• Absolute and relative total bark thickness declined with height, with no difference in height-related changes between habitat groups. Relative outer bark thickness showed a height-by-habitat interaction. There was a clade effect on relative thickness, but no interaction with height. Moisture contents were higher in inner than outer bark, and red oaks had denser bark than white oaks, but neither trait differed by habitat.• Quercus species characteristic of fire-prone habitats invest more in outer bark near the ground where heat damage to outer tissues is most likely. Future investigations of bark should consider the height at which measurements are made and distinguish between inner and outer bark.

Ectopic lignification in the flax lignified bast fiber1 mutant stem is associated with tissue-specific modifications in gene expression and cell wall composition.

Histochemical screening of a flax ethyl methanesulfonate population led to the identification of 93 independent M2 mutant families showing ectopic lignification in the secondary cell wall of stem bast fibers. We named this core collection the Linum usitatissimum (flax) lbf mutants for lignified bast fibers and believe that this population represents a novel biological resource for investigating how bast fiber plants regulate lignin biosynthesis. As a proof of concept, we characterized the lbf1 mutant and showed that the lignin content increased by 350% in outer stem tissues containing bast fibers but was unchanged in inner stem tissues containing xylem. Chemical and NMR analyses indicated that bast fiber ectopic lignin was highly condensed and rich in G-units. Liquid chromatography-mass spectrometry profiling showed large modifications in the oligolignol pool of lbf1 inner- and outer-stem tissues that could be related to ectopic lignification. Immunological and chemical analyses revealed that lbf1 mutants also showed changes to other cell wall polymers. Whole-genome transcriptomics suggested that ectopic lignification of flax bast fibers could be caused by increased transcript accumulation of (1) the cinnamoyl-CoA reductase, cinnamyl alcohol dehydrogenase, and caffeic acid O-methyltransferase monolignol biosynthesis genes, (2) several lignin-associated peroxidase genes, and (3) genes coding for respiratory burst oxidase homolog NADPH-oxidases necessary to increase H2O2 supply.

Enhancing cell migration in shape-memory alginate-collagen composite scaffolds: Invitro and ex vivo assessment for intervertebral disc repair.

Lower lumbar disc disorders pose a significant problem in an aging society with substantial socioeconomic consequences. Both inner tissue (nucleus pulposus) and outer tissue (annulus fibrosus) of the intervertebral disc are affected by such debilitating disorders and can lead to disc herniation and lower back pain. In this study, we developed an alginate-collagen composite porous scaffold with shape-memory properties to fill defects occurring in annulus fibrosus tissue of degenerated intervertebral discs, which has the potential to be administered using minimal invasive surgery. In the first part of this work, we assessed how collagen incorporation on preformed alginate scaffolds influences the physical properties of the final composite scaffold. We also evaluated the ability of annulus fibrosus cells to attach, migrate, and proliferate on the composite alginate-collagen scaffolds compared to control scaffolds (alginate only). Invitro experiments, performed in intervertebral disc-like microenvironmental conditions (low glucose and low oxygen concentrations), revealed that for alginate only scaffolds, annulus fibrosus cells agglomerated in clusters with limited infiltration and migration capacity. In comparison, for alginate-collagen scaffolds, annulus fibrosus cells readily attached and colonized constructs, while preserving their typical fibroblastic-like cell morphology with spreading behavior and intense cytoskeleton expression. In a second part of this study, we investigated the effects of alginate-collagen scaffold when seeded with bone marrow derived mesenchymal stem cells. Invitro, we observed that alginate-collagen porous scaffolds supported cell proliferation and extracellular matrix deposition (collagen type I), with secretion amplified by the local release of transforming growth factor-β3. In addition, when cultured in ex vivo organ defect model, alginate-collagen scaffolds maintained viability of transplanted mesenchymal stem cells for up to 5 weeks. Taken together, these findings illustrate the advantages of incorporating collagen as a means to enhance cell migration and proliferation in porous scaffolds which could be used to augment tissue repair strategies.

Functional ultrastructure of the parenchymatic capsules of the cestode Thysanotaenia congolensis (Cyclophyllidea, Anoplocephalidae, Inermicapsiferinae).

Proglottids from adult Thysanotaenia congolensis from naturally infected black rats Rattus rattus from Santiago Island, Cape Verde, were examined by transmission electron microscopy (TEM). The uterus in mature proglottids is composed of an ephemeral transverse tube or sac that breaks down, releasing eggs into the parenchyma where they are sequestered in groups and encapsulated by parenchymatous layers. In gravid proglottids, eggs accumulate in groups of 6-12 at the distal end of sac-like uterine ducts. As eggs accumulate, the end of the uterine ducts expands until it pinches off, releasing groups of eggs into the parenchyma surrounded by remnants of uterine epithelium. These epithelium-bound groups of eggs remain in the parenchyma until they are encapsulated with several parenchymatous layers, forming parenchymatic egg capsules, typical for mature and gravid proglottids of Inermicapsiferinae. The parenchymatic capsules originate from the medullary parenchyma of immature proglottids, which undergoes differentiation into the three layers of gravid proglottids: (1) an outer connective tissue layer composed of long delicate filaments of unknown chemical nature embedded in a granular extracellular matrix; (2) a middle layer appearing as an accumulation of large closely packed PAS-positive mucous goblets that are intensely metachromatic after toluidine blue staining and (3) an inner compact layer composed of lipid-containing cells, muscle cells with elongated muscle fibres and cells of various sizes and shapes forming or containing calcareous corpuscles. The mature hexacanths of T. congolensis are surrounded by reduced oncospheral envelopes consisting of remnants of a very thin membranous layer of degenerating embryophore with long, irregularly shaped cytoplasmic processes and by remnants of uterine epithelium extending as numerous apical microlamellae into the parenchymatic capsule lumen.

Annulus fibrosus microstructure: an explanation to local heterogeneities

Annulus fibrosus (AF) is the outer tissue of intervertebral discs (IVD). Its peculiar microstructure and biphasic composition, defined by an oriented fibre network embedded in a highly hydrated mat...

A novel technology using transscleral ultrasound to deliver protein loaded nanoparticles

This study was designed to investigate the feasibility of silk fibroin nanoparticles (SFNs) for sustained drug delivery in transscleral ultrasound. Fluorescein isothiocynate labeled bovine serum albumin (FITC-BSA, MW 66.45kDa) was chosen as a model macromolecular protein drug and SFNs were used as nano-carrier systems suitable for ocular drug delivery. Drug loaded nanoparticles (FITC-BSA-SFNs) were first prepared and characterized. In vitro transscleral study under ultrasound exposure (1MHz, 0.5W/cm2, 5min continuous wave) using isolated sclera of rabbit was performed. The posterior eye segment of rabbit was examined for adverse effect by slit-lamp and histology. It was found that FITC-BSA-SFNs possessed sustained release, bioadhesive, and co-permeation characteristics. The ultrasound application significantly improved the penetration efficiency of FITC-BSA-SFNs as compared with passive delivery, meanwhile caused no damages to the ocular tissue and particles themselves. The distribution profile of SFNs revealed rapid and lasting adhesion on the outer scleral tissues, followed by migration into the interior up to one week after treatment. This research suggested a novel non-invasive transscleral administration of macromolecular protein drugs using SFN carriers combining with ultrasound technology.

Histological and cell wall polysaccharide chemical variability among apricot varieties

The variability of histological and cell wall chemical characteristics of apricot were assessed in nine apricot varieties: Harogem, Goldrich, Hargrand, Iranien, Moniqui, Orangered® Bhart, Stark Early Orange, Ravicille and Rouge du Roussillon. For chemical analyses, Iranien and Moniqui were harvested twice at two weeks interval and Goldrich parenchyma was subdivided into inner and outer tissue.Image texture analysis of parenchyma tissue sections allowed distinguishing varieties on the basis of cell and vascular bundle size distributions and tissue organization. Whole parenchyma cell wall sugar composition failed to distinguish varieties. Goldrich outer tissue was richer in arabinose and mannose compared to inner parenchyma. Methyl and acetyl esterification of polysaccharides were better discriminants. The distribution of methyl and acetyl esters on pectin varied among varieties. The tissue regions studied in Goldrich and the different harvests studied in Moniqui and Iranien affected pectin esterification. Hemicellulose fine structure profiles discriminated varieties on the basis of xyloglucan and galactoglucomannan structures proportion.The results point to variations in chemical and histological characteristics that can be of importance in studies on the understanding the genetics of apricots texture variations.

Characterization of biological pathways associated with a 1.37 Mbp genomic region protective of hypertension in Dahl S rats

The goal of the present study was to narrow a region of chromosome 13 to only several genes and then apply unbiased statistical approaches to identify molecular networks and biological pathways relevant to blood-pressure salt sensitivity in Dahl salt-sensitive (SS) rats. The analysis of 13 overlapping subcongenic strains identified a 1.37 Mbp region on chromosome 13 that influenced the mean arterial blood pressure by at least 25 mmHg in SS rats fed a high-salt diet. DNA sequencing and analysis filled genomic gaps and provided identification of five genes in this region, Rfwd2, Fam5b, Astn1, Pappa2, and Tnr. A cross-platform normalization of transcriptome data sets obtained from our previously published Affymetrix GeneChip dataset and newly acquired RNA-seq data from renal outer medullary tissue provided 90 observations for each gene. Two Bayesian methods were used to analyze the data: 1) a linear model analysis to assess 243 biological pathways for their likelihood to discriminate blood pressure levels across experimental groups and 2) a Bayesian graphical modeling of pathways to discover genes with potential relationships to the candidate genes in this region. As none of these five genes are known to be involved in hypertension, this unbiased approach has provided useful clues to be experimentally explored. Of these five genes, Rfwd2, the gene most strongly expressed in the renal outer medulla, was notably associated with pathways that can affect blood pressure via renal transcellular Na(+) and K(+) electrochemical gradients and tubular Na(+) transport, mitochondrial TCA cycle and cell energetics, and circadian rhythms.

Nox4 contribution to H2O2 but not in superoxide production in response to increased tubular flow in the mTAL of Dahl salt‐sensitive rats (1134.3)

Studies were carried out to determine the relative contribution of Nox4 in the production of H2O2 vs. superoxide (O2‐) in the renal medullary thick ascending limb of Henle (mTAL) of Dahl salt‐sensitive (SS) rats. We have previously presented that Nox4 is the major source of H2O2 production in mTAL in response to increased luminal flow. Specifically, knock out of Nox4 in SS rats (SSNox4‐/‐) resulted in significant reduction of intracellular H2O2 production compared to SS. In the present study, using fluorescence microscopy (Eth/DHE ratio), we examined the contribution of Nox4 to O2‐ production in isolated microperfused mTAL in response to an increase of luminal flow (from 5 to 20 nl/min) in SS and SSNox4‐/‐ rats fed a 4% NaCl diet for 3 days. NADPH oxidase activity in outer medullary tissue was determined with DHE fluorescence assay. Results: 1) O2‐ production increased significantly and to the same extent in mTAL of both SS and SSNox4‐/‐ rats. 2) No differences were observed in NADPH activity between the two strains. We conclude that Nox4 contributes only to the production of intracellular H2O2 and not O2‐ in response to increased mTAL luminal flow in SS rats fed a high salt diet.

Annexin A2 mediates apical trafficking of renal Na‐K‐2Cl cotransporter (892.22)

Transport activity of the thick ascending limb (TAL) Na‐K‐2Cl‐cotransporter (NKCC2) critically depends on its association with lipid raft membrane microdomains (LR). The mechanisms involved in the recruitment of NKCC2 into LR have not been elucidated so far. In the present study we hypothesized that the lipid raft scaffolding protein annexin A2 serves as an essential mediator in this process. Detergent‐resistant LR were isolated from rat renal outer medullary tissue samples using discontinuous sucrose density gradient and ultracentrifugation (floating assay). Interaction between NKCC2 and Anxa2 was analyzed by immunoprecipitation, GST pull down, and peptide spot assays. Distribution of the products in the apical TAL membrane was studied by immunofluorescence and immunogold electron microscopy. Trafficking was studied in AVP‐deficient rats and cultured TAL cells using the AVP analogue desmopressin (dDAVP) or low chloride hypotonic stress. Functional relevance of Anxa2 for NKCC2 trafficking was studied using RNAi‐mediated knockdown strategies. Floating assay, immunoprecipitation and colocalization studies confirmed the parallel presence of NKCC2 and Anxa2 in apical membrane LR of the TAL. Binding assays approved physical interaction of Anxa2 and the non‐phosphorylated N‐terminus of NKCC2. Moreover, dDAVP and low chloride hypotonic stress caused parallel trafficking of NKCC2 and Anxa2 in rats and in cultured TAL cells and this response was inhibited by RNAi‐mediated knockdown of Anxa2. In conclusion our data demonstrate that Anxa2 is an essential component of the NKCC2 trafficking protein complex and mediates its recruitment into LR microdomains.

Mechanical modelling quantifies the functional importance of outer tissue layers during root elongation and bending.

Root elongation and bending require the coordinated expansion of multiple cells of different types. These processes are regulated by the action of hormones that can target distinct cell layers. We use a mathematical model to characterise the influence of the biomechanical properties of individual cell walls on the properties of the whole tissue.Taking a simple constitutive model at the cell scale which characterises cell walls via yield and extensibility parameters, we derive the analogous tissue-level model to describe elongation and bending. To accurately parameterise the model, we take detailed measurements of cell turgor, cell geometries and wall thicknesses.The model demonstrates how cell properties and shapes contribute to tissue-level extensibility and yield. Exploiting the highly organised structure of the elongation zone (EZ) of the Arabidopsis root, we quantify the contributions of different cell layers, using the measured parameters. We show how distributions of material and geometric properties across the root cross-section contribute to the generation of curvature, and relate the angle of a gravitropic bend to the magnitude and duration of asymmetric wall softening.We quantify the geometric factors which lead to the predominant contribution of the outer cell files in driving root elongation and bending.

Milling of Canadian oats and barley for functional food ingredients: Oat bran and barley fibre-rich fractions

Izydorczyk, M. S., McMillan, T., Bazin, S., Kletke, J., Dushnicky, L., Dexter, J., Chepurna, A. and Rossnagel, B. 2014. Milling of Canadian oats and barley for functional food ingredients: Oat bran and barley fibre-rich fractions. Can. J. Plant Sci. 94: 573–586. Oats and barley are recognized for their valuable fibre constituents having protective and therapeutic effects against the development of diet-related disorders. Mixed linkage (1–3), (1–4)-β-D-glucans, the major dietary fibre constituents in oats and barley, have been linked to blood cholesterol lowering properties of these grains. The objective of this study was to compare oat bran and barley fibre-rich fractions (FRF) as two products with elevated levels of β-glucans and obtained by similar roller milling processes. The content of β-glucan in oat brans prepared from three different cultivars (AC Morgan, HiFi, and CDC ProFi) ranged from 7.90 to 9.50%, whereas the content of β-glucans in FRF prepared from three barley cultivars (CDC McGwire, CDC Fibar, and CDC Hilose) ranged from 9.31 to 18.19% (dwb). The yields of oat brans ranged from 44 to 49% and the yields of barley FRF from 39–49%. Both preparations contained higher amounts of arabinoxylans, proteins, and ash compared with the original grains. The oat brans were made up mainly of fragments containing the outer grain layers with a substantial portion of the subaleurone starchy endosperm attached to them, whereas the barley FRF consisted primarily of fragments containing the endosperm cell walls, with a smaller proportion of the outer grain tissues. The barley FRF contained smaller particles with broader distribution of particle size than the oat brans. The oat bran particles had higher bulk density and lower porosity than the barley FRF. Both preparations showed pronounced viscosity-building properties when dispersed in water at 45°C, but exhibited different viscosity profiles and differences in the attainable viscosity values.