Showing papers on "Granule (cell biology) published in 2004"
TL;DR: In this article, the authors provide an overview of aspects related to starch granule size, including procedures for determining the size, the impact of granules size on the physicochemical characteristics of starch, and biosynthetic and environmental determinants of granule sizes.
Abstract: Granule size, size distribution and shape are among the most important morphologically distinguishing factors of starches from different origins. This article provides an overview of aspects related to starch granule size, including procedures for determining the size, the impact of granule size on the physicochemical characteristics of starch, and biosynthetic and environmental determinants of granule size. The focus is on small granule starches, including their isolation and current and potential utilization.
644 citations
TL;DR: In this article, the essential role of hydraulic settling time in the formation of aerobic granules was studied in four column sequencing batch reactors (R1, R4, R3 and R4).
222 citations
TL;DR: It is demonstrated that the selection of slow-growing nitrifying bacteria through controlling substrate N/COD ratio would be a useful strategy for improving the stability of aerobic granules.
205 citations
TL;DR: The physicochemical properties of small, medium and large starch granules separated from four potato cultivars were investigated to reveal whether functional properties differed among the various size classes of the starches as discussed by the authors.
Abstract: The physicochemical properties of small, medium and large starch granules separated from four potato cultivars were investigated to reveal whether functional properties differed among the various size classes of the starches. Large-size fractions showed higher amylose content and light transmittance and lower swelling power than small-size fractions. The granules from the three fractions had diameters of 5–20, 25–40 and 40–85 µm respectively. The large and medium granules were ellipsoidal to irregular or cuboidal while the small granules were spherical or ellipsoidal in shape. The transition temperatures and gelatinisation temperature range of the fractionated starches increased while the enthalpy of gelatinisation decreased with decreasing granule size. Rheological parameters such as peak storage (G′) and loss (G″) moduli increased in the order small-, medium- and large-granule starches when subjected to temperature sweep testing. The breakdown in peak G′ during the heating cycle and retrogradation during storage were found to be highest for large- and lowest for small-size fractions. The differences in functional properties among the different size fractions suggested that the granule size distribution is an important parameter that can influence the behaviour of potato starch during processing. Copyright © 2004 Society of Chemical Industry
197 citations
TL;DR: Of particular interest were results from simulations of the protein grown granules, which were predicted to have slow growth rates, low microbial density, and no trophic layers, the last two of which were reflected by microscopic observations.
184 citations
TL;DR: It is shown that β-cell stimulation induces the nucleocytoplasmic translocation of polypyrimidine tract-binding protein (PTB), which binds and stabilizes mRNAs encoding proteins of secretory granules, thus increasing their translation and knockingdown of PTB expression by RNA interference results in the depletion of secretORY granules.
Abstract: Pancreatic β-cells store insulin in secretory granules that undergo exocytosis upon glucose stimulation. Sustained stimulation depletes β-cells of their granule pool, which must be quickly restored. However, the factors promoting rapid granule biogenesis are unknown. Here we show that β-cell stimulation induces the nucleocytoplasmic translocation of polypyrimidine tract-binding protein (PTB). Activated cytosolic PTB binds and stabilizes mRNAs encoding proteins of secretory granules, thus increasing their translation, whereas knockdown of PTB expression by RNA interference (RNAi) results in the depletion of secretory granules. These findings may provide insight for the understanding and treatment of diabetes, in which insulin secretion is typically impaired.
177 citations
TL;DR: It is concluded that a significant fraction of chromaffin granules re‐seal after exocytosis, and retain those proteins that leave granules slowly, and suggest that granules vary the stoichiometry of release by varying both granule re-sealing and the association of proteins with the granule matrix.
Abstract: After exocytosis, chromaffin granules release essentially all their catecholamines in small fractions of a second, but it is unknown how fast they release stored peptides and proteins. Here we compare the exocytic release of fluorescently labelled neuropeptide Y (NPY) and tissue plasminogen activator from single granules. Exocytosis was tracked by measuring the membrane capacitance, and single granules in live cells were imaged by evanescent field microscopy. Neuropeptide Y left most granules in small fractions of a second, while tissue plasminogen activator remained in open granules for minutes. Taking advantage of the dependence on pH of the fluorescence of green fluorescent protein, we used rhythmic external acidification to determine whether and when granules re-sealed. One-third of them re-sealed within 100 s and retained significant levels of tissue plasminogen activator. Re-sealing accounts for only a fraction of the endocytosis monitored in capacitance measurements. When external [Ca2+] was raised, even neuropeptide Y remained in open granules until they re-sealed. It is concluded that a significant fraction of chromaffin granules re-seal after exocytosis, and retain those proteins that leave granules slowly. We suggest that granules vary the stoichiometry of release by varying both granule re-sealing and the association of proteins with the granule matrix.
164 citations
TL;DR: The results indicate that the decreased number of docked insulin granules accounts for the impaired insulin release during the first phase of insulin release in diabetic GK rat beta-cells.
Abstract: We imaged and analysed the motion of single insulin secretory granules near the plasma membrane in live pancreatic β-cells, from normal and diabetic Goto–Kakizaki (GK) rats, using total internal reflection fluorescence microscopy (TIRFM). In normal rat primary β-cells, the granules that were fusing during the first phase originate from previously docked granules, and those during the second phase originate from ‘newcomers’. In diabetic GK rat β-cells, the number of fusion events from previously docked granules were markedly reduced, and, in contrast, the fusion from newcomers was still preserved. The dynamic change in the number of docked insulin granules showed that, in GK rat β-cells, the total number of docked insulin granules was markedly decreased to 35% of the initial number after glucose stimulation. Immunohistochemistry with anti-insulin antibody observed by TIRFM showed that GK rat β-cells had a marked decline of endogenous insulin granules docked to the plasma membrane. Thus our results indicate that the decreased number of docked insulin granules accounts for the impaired insulin release during the first phase of insulin release in diabetic GK rat β-cells.
163 citations
TL;DR: It is concluded that intermittent feeding associated with the SBR affects the selection and growth of filamentous organisms and has a critical role in granule structure and composition.
145 citations
TL;DR: Overall granule behavior before and during fusion is strikingly similar to exocytosis previously described in the constitutive secretory pathway.
Abstract: Secretory granules labeled with Vamp-green fluorescent protein (GFP) showed distinct signatures upon exocytosis when viewed by total internal reflection fluorescence microscopy. In approximately 90% of fusion events, we observed a large increase in fluorescence intensity coupled with a transition from a small punctate appearance to a larger, spreading cloud with free diffusion of the Vamp-GFP into the plasma membrane. Quantitation suggests that these events reflect the progression of an initially fused and spherical granule flattening into the plane of the plasma membrane as the Vamp-GFP simultaneously diffuses through the fusion junction. Approximately 10% of the events showed a transition from puncta to ring-like structures coupled with little or no spreading. The ring-like images correspond quantitatively to granules fusing and retaining concavity (recess of approximately 200 nm). A majority of fusion events involved granules that were present in the evanescent field for at least 12 s. However, approximately 20% of the events involved granules that were present in the evanescent field for no more than 0.3 s, indicating that the interaction of the granule with the plasma membrane that leads to exocytosis can occur within that time. In addition, approximately 10% of the exocytotic sites were much more likely to occur within a granule diameter of a previous event than can be accounted for by chance, suggestive of sequential (piggy-back) exocytosis that has been observed in other cells. Overall granule behavior before and during fusion is strikingly similar to exocytosis previously described in the constitutive secretory pathway.
130 citations
TL;DR: Rho-dependent F-actin coating of granule membranes thus stabilizes exocytic structures and is necessary for physiological progression of sequetial compound exocytosis in the exocrine pancreas and for prevention of acute pancreatitis.
TL;DR: A functional model of the microbial community within the aerobic granules was proposed and has important implications for rationalizing the engineering of ecological systems.
Abstract: Phenol is a major pollutant in industrial wastewater, and its removal is of obvious interest. Biological treatment of phenol is generally preferred to physical or chemical treatment methods because of lower costs and the possibility of complete mineralization. However, conventional biological treatment systems such as the activated sludge process are known to be sensitive to high phenol loading rates and fluctuations in phenol loading due to substrate inhibition from phenol toxicity (44).
These substrate inhibition difficulties can be overcome by strategies such as cell immobilization to protect microbial cells against phenol toxicity (24). Aerobic granulation is a recently reported form of cell immobilization technology that is attracting considerable research attention (27, 38). Aerobic granules are self-immobilized aggregates of microorganisms formed in engineered systems such as sequencing batch reactors (SBRs). Unlike activated sludge flocs, microbial granules have a well-defined appearance and are still visible as separate entities after settling (9). Granulation facilitates the accumulation of high amounts of active biomass and the effective separation of this biomass from the wastewater liquor. Early studies of aerobic granulation involved the use of benign substrates such as glucose and acetate (38, 39). Several recent studies reported the successful cultivation of aerobic granules using toxic phenol as a substrate and examined the effect of phenol loading on granule structure, activity, and metabolism (13, 14).
While the microbial diversities of glucose-fed aerobic granules and phenol-degrading activated sludge have been reasonably well described (39, 43, 44), a gap in our understanding of the microbial communities residing in phenol-degrading aerobic granules still exists. Aerobic granules can be viewed as a special form of biofilm but without carriers for biofilm attachment. Growth environments for biofilm communities are different from those for planktonic communities, and microbial communities in attached biofilms have been shown to be highly distinct from the suspended biomass, even within a single reactor system (4, 8). Recent studies stress the importance of gaining an understanding of the functions of microbial communities, as population diversity alone may not be adequate in maintaining ecosystem stability. Recognizing the diversity and the links within the key functional groups in a given system can lead to better ways to model diversity and function as well as to improve process stability (3, 12, 16).
In this study, culture-independent and culture-dependent methods were used in combination to study the microbial community of phenol-degrading aerobic granules and to isolate, characterize, and identify ecologically relevant microorganisms. One of the isolates demonstrated a strong ability to degrade phenol and maintained a dominant presence within the granule community. A second isolate showed a weak ability to degrade phenol but was exceptional in its ability to autoaggregate. Based on these observations, a functional model of the microbial community in the aerobic granules was proposed. This work is expected to be useful in understanding the ecology and function of aerobic granules and in developing optimal control and management strategies for aerobic granulation systems.
TL;DR: It is concluded that glucose and second messengers can modulate insulin release triggered by a high-affinity Ca2+ sensor that is poised to respond to modest, global elevations of [Ca2+]i.
Abstract: We have used membrane capacitance measurements and carbon-fiber amperometry to assay exocytosis triggered by photorelease of caged Ca2+ to directly measure the Ca2+ sensitivity of exocytosis from the INS-1 insulin-secreting cell line. We find heterogeneity of the Ca2+ sensitivity of release in that a small proportion of granules makes up a highly Ca2+-sensitive pool (HCSP), whereas the bulk of granules have a lower sensitivity to Ca2+. A substantial HCSP remains after brief membrane depolarization, suggesting that the majority of granules with high sensitivity to Ca2+ are not located close to Ca2+ channels. The HCSP is enhanced in size by glucose, cAMP, and a phorbol ester, whereas the Ca2+-sensitive rate constant of exocytosis from the HCSP is unaffected by cAMP and phorbol ester. The effects of cAMP and phorbol ester on the HCSP are mediated by PKA and PKC, respectively, because they can be blocked with specific protein kinase inhibitors. The size of the HCSP can be enhanced by glucose even in the presence of high concentrations of phorbol ester or cAMP, suggesting that glucose can increase granule pool sizes independently of activation of PKA or PKC. The effects of PKA and PKC on the size of the HCSP are not additive, suggesting they converge on a common mechanism. Carbon-fiber amperometry was used to assay quantal exocytosis of serotonin (5-HT) from insulin-containing granules following preincubation of INS-1 cells with 5-HT and a precursor. The amount or kinetics of release of 5-HT from each granule is not significantly different between granules with higher or lower sensitivity to Ca2+, suggesting that granules in these two pools do not differ in morphology or fusion kinetics. We conclude that glucose and second messengers can modulate insulin release triggered by a high-affinity Ca2+ sensor that is poised to respond to modest, global elevations of [Ca2+]i.
TL;DR: In this Traffic Interchange, the two co‐authors attempt to reconcile their differences, leading to a common vision of proinsulin trafficking in primary and transformed cells.
Abstract: Biogenesis of the regulated secretory pathway in the pancreatic beta-cell involves packaging of products, notably proinsulin, into immature secretory granules derived from the trans-Golgi network. Proinsulin is converted to insulin and C-peptide as granules mature. Secretory proteins not entering granules are conveyed by transport intermediates directly to the plasma membrane for constitutive secretion. One of the co-authors, Peter Arvan, has proposed that in addition, small vesicles bud from granules to traffic to the endosomal system. From there, some proteins are secreted by a (post-granular) constitutive-like pathway. He argues that retention in granules is facilitated by condensation, rendering soluble products (notably C-peptide and proinsulin) more available for constitutive-like secretion. Thus he argues that prohormone conversion is potentially important in secretory granule biogenesis. The other co-author, Philippe Halban, argues that the post-granular secretory pathway is not of physiological relevance in primary beta-cells, and contests the importance of proinsulin conversion for retention in granules. Both, however, agree that trafficking from granules to endosomes is important, purging granules of unwanted newly synthesized proteins and allowing their traffic to other destinations. In this Traffic Interchange, the two co-authors attempt to reconcile their differences, leading to a common vision of proinsulin trafficking in primary and transformed cells.
TL;DR: The results suggest that expression of regulated cargo proteins is sufficient to generate structures that resemble secretory granules in the background of constitutively secreting cells, supporting earlier proposals on the mechanism of granule formation.
TL;DR: Perinuclear nuage is a stable structure that maintains size, seldom detaches from the nuclear envelope and exchanges protein components with the cytoplasm, consistent with a model in which nuage facilitates post transcriptional regulation by promoting the formation or reorganization of RNA-protein complexes.
Abstract: Nuage, a germ line specific organelle, is remarkably conserved between species, suggesting that it has an important germline cell function. Very little is known about the specific role of this organelle, but in Drosophila three nuage components have been identified, the Vasa, Tudor and Aubergine proteins. Each of these components is also present in polar granules, structures that are assembled in the oocyte and specify the formation of embryonic germ cells. We used GFP-tagged versions of Vasa and Aubergine to characterize and track nuage particles and polar granules in live preparations of ovaries and embryos. We found that perinuclear nuage is a stable structure that maintains size, seldom detaches from the nuclear envelope and exchanges protein components with the cytoplasm. Cytoplasmic nuage particles move rapidly in nurse cell cytoplasm and passage into the oocyte where their movements parallel that of the bulk cytoplasm. These particles do not appear to be anchored at the posterior or incorporated into polar granules, which argues for a model where nuage particles do not serve as the precursors of polar granules. Instead, Oskar protein nucleates the formation of polar granules from cytoplasmic pools of the components shared with nuage. Surprisingly, Oskar also appears to stabilize at least one shared component, Aubergine, and this property probably contributes to the Oskar-dependent formation of polar granules. We also find that Bruno, a translational control protein, is associated with nuage, which is consistent with a model in which nuage facilitates post transcriptional regulation by promoting the formation or reorganization of RNA-protein complexes.
TL;DR: In this article, the degree of substitution (DS) and degradability of amylopectin and amyloglucosidase fractions of potato and sweet potato granules were analyzed.
TL;DR: It is concluded that insulin exocytosis involves a prolonged interaction of secretory granules with the plasma membrane, and that the majority ofExocytotic events occur by full, not partial, fusion.
Abstract: Confocal imaging of GFP-tagged secretory granules combined with the use of impermeant extracellular dyes permits direct observation of insulin packaged in secretory granules, trafficking of these granules to the plasma membrane, exocytotic fusion of granules with the plasma membrane, and eventually the retrieval of membranes by endocytosis. Most such studies have been done in tumor cell lines, using either confocal methods or total internal reflectance microscopy. Here we compared these methods by using GFP-syncollin or PC3-GFP plus rhodamine dextrans to study insulin granule dynamics in insulinoma cells, normal mouse islets, and primary pancreatic beta cells. We found that most apparently docked granules did not fuse with the plasma membrane after stimulation. Granules that did fuse typically fused completely, but a few dextran-filled granules lingered at the membrane. Direct recycling of granules occurred only rarely. Similar results were obtained with both confocal and total internal reflection microscopy, although each technique had advantages for particular aspects of the granule life cycle. We conclude that insulin exocytosis involves a prolonged interaction of secretory granules with the plasma membrane, and that the majority of exocytotic events occur by full, not partial, fusion.
TL;DR: Only with extremely high release rates, glucose stimulation after a 4-h incubation with a high concentration of fatty acid-free BSA, was the docked granule pool reduced in size, suggesting a limit to the number of docking sites.
Abstract: Electron microscopy and quantitative stereological techniques were used to study the dynamics of the docked granule pool in the rat pancreatic beta-cell. The mean number of granules per beta-cell was 11,136. After equilibration in RPMI containing 5.6 mmol/l glucose, 6.4% of the granules (approximately 700) were docked at the plasma membrane (also measured as [means +/- SE] 4.3 +/- 0.6 docked granules per 10 microm of plasma membrane at the perimeter of the cell sections). After a 40-min exposure to 16.7 mmol/l glucose, 10.2% of the granules (approximately 1,060) were docked (6.4 +/- 0.8 granules per 10 microm of plasma membrane). Thus, the docked pool increased by 50% during stimulation with glucose. Islets were also exposed to 16.7 mmol/l glucose in the absence or presence of 10 micromol/l nitrendipine. In the absence and presence of nitrendipine, there were 6.1 +/- 0.7 and 6.3 +/- 0.6 granules per 10 microm of membrane, respectively. Thus, glucose increased granule docking independently of increased [Ca2+]i and exocytosis. The data suggest a limit to the number of docking sites. As the rate of docking exceeded the rate of exocytosis, docking is not rate limiting for insulin release. Only with extremely high release rates, glucose stimulation after a 4-h incubation with a high concentration of fatty acid-free BSA, was the docked granule pool reduced in size.
TL;DR: To directly visualize and study the dynamics of both the release and tissue activity of renin, isolated and perfused afferent arterioles with attached glomeruli dissected from rabbit kidneys and used multiphoton fluorescence imaging.
Abstract: Renin release from juxtaglomerular granular cells is considered the rate-limiting step in activation of the renin-angiotensin system that helps to maintain body salt and water balance. Available assays to measure renin release are complex, indirect, and work with significant internal errors. To directly visualize and study the dynamics of both the release and tissue activity of renin, we isolated and perfused afferent arterioles with attached glomeruli dissected from rabbit kidneys and used multiphoton fluorescence imaging. Acidotropic fluorophores, such as quinacrine and LysoTrackers, clearly and selectively labeled renin granules. Immunohistochemistry of mouse kidney with a specific renin antibody and quinacrine staining colocalized renin granules and quinacrine fluorescence. A low-salt diet for 1 wk caused an approximately fivefold increase in the number of both individual granules and renin-positive granular cells. Time-lapse imaging showed no signs of granule trafficking or any movement, only the dimming and disappearance of fluorescence from individual renin granules within 1 s in response to 100 μM isoproterenol. There appeared to be a quantal release of the granular contents; i.e., an all-or-none phenomenon. Using As4.1 cells, a granular cell line, we observed further classic signs of granule exocytosis, the emptying of granule content associated with a flash of quinacrine fluorescence. Using a fluorescence resonance energy transfer-based, 5-(2-aminoethylamino)naphthalene-1-sulfonic acid (EDANS)-conjugated renin substrate in the bath, an increase in EDANS fluorescence (renin activity) was observed around granular cells in response to isoproterenol. Fluorescence microscopy is an excellent tool for the further study of the mechanism, regulation, and dynamics of renin release.
TL;DR: Findings implicate a role for ZnT4 in mast cell Zn homeostasis and suggest that granule pools of Zn may be distinct from those regulating activation of procaspase-3 and NF-κB.
Abstract: The granules of mast cells and other inflammatory cells are known to be rich in zinc (Zn), a potent caspase inhibitor. The functions of granular Zn, its mechanism of uptake, and its relationship to caspase activation in apoptosis are unclear. The granules of a variety of mast cell types fluoresced intensely with the Zn-specific fluorophore Zinquin, and fluorescence was quenched by functional depletion of Zn using a membrane-permeable Zn chelator N, N, N', N'-tetrakis (2-pyridyl-methyl)ethylenediamine (TPEN). Zn levels were also depleted by various mast cell activators, including IgE/anti-IgE, and Zn was rapidly replenished during subsequent culture, suggesting an active uptake mechanism. In support of the latter, mast cells contained high levels of the vesicular Zn transporter ZnT(4), especially in the more apical granules. Immunofluorescence and immunogold labeling studies revealed significant pools of procaspase-3 and -4 in mast cell granules and their release during degranulation. Functional depletion of Zn by chelation with TPEN, but not by degranulation, resulted in greatly increased susceptibility of mast cells to toxin-induced caspase activation, as detected using a fluorogenic substrate assay. Release of caspases during degranulation was accompanied by a decreased susceptibility to toxins. Zn depletion by chelation, but not by degranulation, also resulted in nuclear translocation of the antiapoptotic, proinflammatory transcription factor NF-kappaB. These findings implicate a role for ZnT(4) in mast cell Zn homeostasis and suggest that granule pools of Zn may be distinct from those regulating activation of procaspase-3 and NF-kappaB.
TL;DR: Paneth cell granules in human small intestine may be depleted in response to infective and nutritional stress, and it is postulate that this is one mechanism through which zinc status influences host susceptibility to intestinal infection.
Abstract: Paneth cells are important contributors to the intestinal antimicrobial barrier through synthesis and release of antimicrobial peptides and proteins. Animal studies indicate that Paneth cell numbers, location and granule morphology are altered by infection and zinc status. We examined human tissue to determine whether Paneth cell numbers, distribution or granule morphology are altered in infective, inflammatory and nutritional disorders. Archival sections from infective disorders (giardiasis, cryptosporidiosis, HIV, helminth infection) were compared with active inflammatory conditions (coeliac, Crohn's and graft-versus-host diseases) and histologically normal tissues. A subset of tissues was studied by electron microscopy and TUNEL staining for apoptosis. Human defensin-5 (HD5) peptide and mRNA was analysed by immunohistochemistry, in situ hybridization and quantitative reverse transcription polymerase chain reaction. Sections from a tropical population cohort study were then analysed to determine the relationship of granule depletion to infection, nutritional status and plasma zinc concentration. In HIV-related cryptosporidiosis, but not other disorders, Paneth cells were reduced in number and markedly depleted of granules. Paneth cell granule depletion was associated with reduced HD5 immunoreactivity, but this was not due to apoptosis and there was no reduction in mRNA transcripts. In the tropical population studied, depletion of granules was associated with reduced body mass index, reduced plasma zinc levels and HIV infection. Paneth cell granules in human small intestine may be depleted in response to infective and nutritional stress. We postulate that this is one mechanism through which zinc status influences host susceptibility to intestinal infection.
TL;DR: The steam granulation technique resulted a suitable method to comply the purpose of this work, without modifying the availability of the drug.
TL;DR: It is concluded that the starch synthesis enzymes, including the GBSSI fragments, are integral components of the granule, whereas the other granule-bound proteins are attached to the surface.
TL;DR: This paper attempts to develop a kinetic model to describe the growth of aerobic granules developed under different operation conditions and shows positive results in both aerobic and non-aer aerobic models.
Abstract: Aims: This paper attempts to develop a kinetic model to describe the growth of aerobic granules developed under different operation conditions.
Methods and Results: A series of experiments were conducted by using four-column sequencing batch reactors to study the formation of aerobic granules under different conditions, e.g. organic loading rates, hydrodynamic shear forces and substrate N/COD ratios. A simple kinetic model based on the Linear Phenomenological Equation was successfully derived to describe the growth of aerobic granules. It was found that the growth of aerobic granules in terms of equilibrium size and size-dependent growth rate were inversely related to shear force imposed to microbial community, while a high organic loading favoured the growth of aerobic granules, leading to a large size granule. The effect of substrate N/COD ratio on the growth kinetics of aerobic granules was realized through change in microbial populations, and enriched nitrifying population in aerobic granules developed at high substrate N/COD ratio resulted in a low overall growth rate of aerobic granules.
Conclusions: The proposed model can provide good prediction for the growth of aerobic granules indicated by the correlation coefficient >0·95.
Significance and Impact of the Study: The kinetic model proposed could offer a useful tool for studying the growth kinetics of cell-to-cell immobilization process. The study confirmed that the growth of aerobic granules and biofilms are subject to a similar kinetic pattern. This work would also be helpful for better understanding the mechanism of aerobic granulation.
TL;DR: In this article, the discovery of channels ID starch granules and progress of research on their effects on granule modification and digestibility, their nature, hypotheses on how they are formed and why they are present, and genetic control of their occurrence.
Abstract: This paper reviews the discovery of channels ID starch granules and progress of research on their effects on granule modification and digestibility, their nature, hypotheses on how they are formed and why they are present, and genetic control of their occurrence. Emphasized ID the relationship of channels to starch derivatization. Channelization ID presented as additional evidence of the heterogenous nature of starch granules from source to source and within a single source. A new method of determining the location of anionic entities within starch granules that utilizes reflectance confocal laser scanning microscopy ID described.
TL;DR: In Tetrahymena thermophila, biochemical and genetic approaches have begun yielding insights into issues ranging from control of granule core assembly, based on reverse genetic analysis ofgranule cargo, to questions about factors involved in granule biogenesis, based in random mutational approaches.
Abstract: The release of polypeptides in response to extracellular cues is a notable feature of endocrine, exocrine and neuronal cells, and is based on regulated exocytosis via dense-core secretory granules. There is interest in this mode of secretion because of its importance in human physiology and also because regulated exocytosis reflects a complex pathway of membrane traffic that includes compartment-specific reversible macromolecular assembly, coat-independent vesicle budding, maturation/remodeling of both lumenal and membrane constituents, and stimulus-dependent membrane fusion. Secretory granules are absent in most unicellular model organisms but are highly developed in the Ciliates, which therefore offer attractive systems to study these phenomena. In Tetrahymena thermophila, biochemical and genetic approaches have begun yielding insights into issues ranging from control of granule core assembly, based on reverse genetic analysis of granule cargo, to questions about factors involved in granule biogenesis, based on random mutational approaches.
TL;DR: It is demonstrated that aerobic granules can be developed to achieve high phenol loading rates in a sequencing batch reactor and remained stable, without significant deterioration in granule structure and physiology, even at the maximum Phenol loading rate tested.
Abstract: This study demonstrates that aerobic granules can be developed to achieve high phenol loading rates in a sequencing batch reactor. The reactor was started at a loading rate of 1.5 kgphenolm-3d-1 with phenol-enriched activated sludge as inoculum. Granules first appeared on Day 9 after startup and quickly grew to become the dominant biomass in the reactor. The phenol loading was then adjusted stepwise to a final value of 2.5 kgphenolm-3d-1. At this high loading, phenol was completely degraded and high biomass concentration was maintained in the reactor. The biomass continued to possess a good settling ability, with a sludge volume index of 60.5 mLgSS-1 (SS stands for suspended solids). Granules remained stable, without significant deterioration in granule structure and physiology, even at the maximum phenol loading rate tested. The applied selection pressure enabled the micro-organisms to aggregate into granules, and the compact structure of the aerobic granules served both to retain biomass and protect the...
TL;DR: Both the optimized minitablet formulation and the granule formulation show suitable release profiles for the delivery of peptide drugs with TMC as absorption enhancer in solid oral dosage forms.
TL;DR: In this article, the authors examined morphological and ultrastructural changes of waxy, normal and high-amylose barley starch granules heated in water to various temperatures.