Number Of Granules Research Articles

Neonatal Platelets: Lower G12/13 Expression Contributes to Reduced Secretion of Dense Granules.

Despite fully functional primary hemostasis, platelets of healthy neonates exhibit hypoaggregability and secretion defects, which may be adaptations to specific requirements in this developmental stage. The etiologies for reduced signal transduction vary with the type of agonist. The discovered peculiarities are lower receptor densities, reduced calcium mobilization, and functional impairments of G proteins. Reduced secretion of dense granules has been attributed to lower numbers of granules. Signaling studies with adult platelets have shown a regulating effect of the G12/13 signaling pathway on dense granule secretion via RhoA. We comparatively analyzed secretion profiles using flow cytometry and expression levels of Gq, Gi, and G12/13 using Western blot analysis in platelets from cord blood and adults. Furthermore, we evaluated Rho activation after in vitro platelet stimulation with thrombin using a pulldown assay. We observed a markedly reduced expression of the dense granule marker CD63 on neonatal platelets after thrombin stimulation. Gα12/13 expression was significantly decreased in neonatal platelets and correlated with lower Rho activation after thrombin stimulation. We conclude that lower expression of G12/13 in neonatal platelets results in attenuated activation of Rho and may contribute to reduced secretion of dense granules after exposure to thrombin.

Third-Generation Platelet Concentrates in Periodontal Regeneration: Gaining Ground in the Field of Regeneration.

Platelets are important for hemostasis and the healing of wounds. In clinical settings, healing cytokines including insulin-like growth factors (IGF), platelet-derived growth factors (PDGF), and transforming growth factors (TGF) are commonly implemented. The regenerative approach in dentistry frequently employs platelet concentrates (PCs) that are “autologous in origin” and have a high concentration of platelets, growth factors, and leukocytes. First-generation PCs is made of platelet-rich plasma (PRP), while second-generation PC is made of platelet-rich fibrin (PRF). Both have limitations, so modification protocols and development in PRP and PRF derivatives are required for advancement mechanisms, strength, biodegradability, retention ability in the field of regenerative dentistry, and so on. As third-generation PC, newer genera kinds of PRF, such as advanced-PRF (A-PRF), advanced-PRF+ (A-PRF+), injectable-PRF (i-PRF), and titanium-PRF (T-PRF), were introduced. A-PRF matrices in their solid form were introduced using the low-speed centrifugation concept (LSCC). The applied relative centrifugal force (RCF) for A-PRF is reduced to 208 g as a result of this improved preparation process. A-PRF features a greater number of neutrophil granules in the distal region, especially at the red blood cells-buffer coat (RBC-BC) interface, and the A-PRF clot has a more porosity-like structure with a bigger interfibrous space than PRF. Since the PRF is in a gel form and is difficult to inject, i-PRF was formulated to address this problem. Compared to the other two protocols, the i-PRF protocol requires far less time, and this is the advantage of this PC. This is because i-PRF just needs the blood components to be separated, which happens within the first two to four minutes. Compared to normal L-PRF, T-PRF creates fibrin that is thicker and more densely woven. Titanium has a higher hemocompatibility than glass, which could lead to greater polymerized fibrin formation. In periodontal regenerative operations, oral surgery, and implant dentistry, PRF and its newer advanced modifications have demonstrated promising results and desirable results in both soft and hard tissue regenerative techniques.

Imeglimin exerts favorable effects on pancreatic β-cells by improving morphology in mitochondria and increasing the number of insulin granules

Imeglimin is a new anti-diabetic drug commercialized in Japan (Twymeeg®) and has been drawing much attention in diabetes research area as well as in clinical practice. In this study, we evaluated the effect of imeglimin on pancreatic β-cells. First, single-dose administration of imeglimin enhanced insulin secretion from β-cells and decreased blood glucose levels in type 2 diabetic db/db mice. In addition, single-dose administration of imeglimin significantly augmented insulin secretion in response to glucose from islets isolated from non-diabetic db/m mice. Second, during an oral glucose tolerance test 4-week chronic treatment with imeglimin enhanced insulin secretion and ameliorated glycemic control in diabetic db/db mice. Furthermore, the examination with electron microscope image showed that imeglimin exerted favorable effects on morphology in β-cell mitochondria and substantially increased the number of insulin granules in type 2 diabetic db/db and KK-Ay mice. Finally, imeglimin reduced the percentage of apoptotic β-cell death which was accompanied by reduced expression levels of various genes related to apoptosis and inflammation in β-cells. Taken together, imeglimin directly enhances insulin secretion in response to glucose from β-cells, increases the number of insulin granules, exerts favorable effects on morphology in β-cell mitochondria, and reduces apoptotic β-cell death in type 2 diabetic mice, which finally leads to amelioration of glycemic control.

Information granulation-based fuzzy partition in decision tree induction

In this study, an interval information granulation-based fuzzy partition (InterIG-FP) method is established to define fuzzy items in the framework of fuzzy decision tree induction. The proposed method first employs the principle of justifiable granularity to build information granules in terms of different classes on different condition attributes, where the number of information granules is equal to the number of classes. Then, the average values of the representative samples determined by each information granule are utilized to define the membership functions of fuzzy items for each condition attribute. Finally, an interval information granulation-based fuzzy decision tree (InterIG-FDT) is constructed based on the predefined fuzzy items in a top-down recursive way. The experiments illustrate the effectiveness, comparability and immunity capability of the proposed method. The effectiveness is verified by some comparative analysis with several traditional no-fuzzy decision trees. Furthermore, under the same constructing framework, some fuzzy decision trees with different fuzzy partition methods are studied to show the comparability on classification accuracies and the immunity capability on noise data, respectively.

Effect of enhanced UV-B radiation on growth and photosynthetic physiology of Iris tectorum maxim.

Iris tectorum Maxim. is an important plant that plays a very crucial role in the ecological welfare of wetlands. In this study, the effects of different intensities of UV-B radiation on the growth, photosynthetic pigment content, chlorophyll fluorescence characteristics, chloroplast ultrastructure, and gas exchange parameters of Iris tectorum Maxim. were studied. The results showed that enhanced UV-B radiation had a significant influence on the above-mentioned parameters of iris. Compared with the control, enhanced UV-B radiation caused certain damage to the leaf appearance. With the increasing intensity of radiation, the apparent damage degree became more serious. Enhanced UV-B radiation significantly decreased leaf chlorophyll contents, and the effect accumulated with the exposure time. Enhanced UV-B radiation increased Fo, significantly increased the non-photochemical quenching coefficient NPQ, reduced PSII and Qp, and significantly decreased the Fm, Fv/Fm, and Fv/Fo in leaves. The effect of UV-B radiation on PSII destruction of Iris tectorum Maxim. increased as the radiation intensity increased and the exposure time prolonged. The chloroplast structure was damaged under the enhanced UV-B radiation. More specifically, thylakoid lamellae were distorted, swelling and even blurred, and a large number of starch granules appeared. The effect of the high intensity of radiation on chloroplast ultrastructure was greater than that of lower intensity. Enhanced UV-B radiation reduced significantly the net photosynthetic rate, stomatal conductance, and transpiration rate, and the degree of degradation increased with the increasing irradiation intensity. However, the intercellular CO2 content increased, which suggests that the main reason for the decrease of photosynthetic rate was the non-stomatal factors.

A deep learning counting model applied to quality control

PurposeThis paper aims to present two different methods to speed up a test used in the sanitary ware industry that requires to count the number of granules that remains in the commodity after flushing. The test requires that 2,500 granules are added to the lavatory and less than 125 remain.Design/methodology/approachThe problem is approached using two deep learning computer vision (CV) models. The first model is a Vision Transformers (ViT) classification approach and the second one is a U-Net paired with a connected components algorithm. Both models are trained and evaluated using a proprietary data set of 3,518 labeled images, and performance is compared.FindingsIt was found that both algorithms are able to produce competitive solutions. The U-Net algorithm achieves accuracy levels above 94% and the ViT model reach accuracy levels above 97%. At this time, the U-Net algorithm is being piloted and the ViT pilot is at the planning stage.Originality/valueTo the best of the authors’ knowledge, this is the first approach using CV to solve the granules problem applying ViT. In addition, this work updates the U-Net-Connected components algorithm and compares the results of both algorithms.

Genome-wide CRISPR screen identified a role for commander complex mediated ITGB1 recycling in basal insulin secretion

ObjectivesPancreatic beta cells secrete insulin postprandially and during fasting to maintain glucose homeostasis. Although glucose-stimulated insulin secretion (GSIS) has been extensively studied, much less is known about basal insulin secretion. Here, we performed a genome-wide CRISPR/Cas9 knockout screen to identify novel regulators of insulin secretion. MethodsTo identify genes that cell autonomously regulate insulin secretion, we engineered a Cas9-expressing MIN6 subclone that permits irreversible fluorescence labeling of exocytic insulin granules. Using a fluorescence-activated cell sorting assay of exocytosis in low glucose and high glucose conditions in individual cells, we performed a genome-wide CRISPR/Cas9 knockout screen. ResultsWe identified several members of the COMMD family, a conserved family of proteins with central roles in intracellular membrane trafficking, as positive regulators of basal insulin secretion, but not GSIS. Mechanistically, we show that the Commander complex promotes insulin granules docking in basal state. This is mediated, at least in part, by its function in ITGB1 recycling. Defective ITGB1 recycling reduces its membrane distribution, the number of focal adhesions and cortical ELKS-containing complexes. ConclusionsWe demonstrated a previously unknown function of the Commander complex in basal insulin secretion. We showed that by ITGB1 recycling, Commander complex increases cortical adhesions, which enhances the assembly of the ELKS-containing complexes. The resulting increase in the number of insulin granules near the plasma membrane strengthens basal insulin secretion.

Investigating Biases Associated With Dietary Starch Incorporation and Retention With an Oral Biofilm Model

Dental calculus has proven to contain a wealth of information on the dietary habits of past populations. These insights have, to a large extent, been obtained by the extraction and identification of starch granules contained within the mineralised dental plaque from a wide range of regions and time periods. The scope of previous studies have been limited to microfossil extraction and identification to reconstruct dietary preferences from the archaeological record, and few studies have attempted to address the biases of starch retention in dental calculus. Those that have considered this problem have been limited to in vivo studies on modern humans and non-human primates. Here, we present a multispecies oral biofilm model, which allows experimental research on starch incorporation and retention to be conducted on in vitro dental calculus in a controlled laboratory setting. The biofilms were exposed to treatment solutions with known quantities of dietary starches (wheat and potato) during the 25 days growth period. After this, the starch granules were extracted from the mature biofilm (by dissolution in EDTA), and counted. We show that the granule counts extracted from the model dental calculus represented a low proportion (ranging from 0.06% to 0.16%) of the total number of granules exposed to the biofilms throughout the experiment. Additionally, we found that the ratios of granule sizes from the extracted starch granules differed from the original treatment solutions, with large granules (>20 μm) consistently being under-represented. We also found a positive correlation between the absolute granule counts and dry-weight of the biofilm (r = 0.659, 90%CI[0.463, 0.794]), meaning the absolute quantity of starch granules will increase as the size of the calculus deposit increases. A similar, but weaker correlation was found between the concentration (count per mg) of granules and dry-weight (r = 0.3, 90%CI[0.0618, 0.506]). Our results complement and reinforce previous in vivo studies suggesting that dental calculus presents a very small, and partly biased picture of the original dietary intake of starches, with an over-representation of plants producing granules smaller than 20 μm in size. The experimental model presented here is well-suited to address the need for further validation of methods and biases associated with dietary research on dental calculus.

Mucins MUC5AC and MUC5B Are Variably Packaged in the Same and in Separate Secretory Granules.

Rationale: MUC5AC (mucin 5AC, oligomeric gel-forming) and MUC5B (mucin 5B, oligomeric gel-forming) are the predominant secreted polymeric mucins in mammalian airways. They contribute differently to the pathogenesis of various muco-obstructive and interstitial lung diseases, and their genes are separately regulated, but whether they are packaged together or in separate secretory granules is not known. Objectives: To determine the packaging of MUC5AC and MUC5B within individual secretory granules in mouse and human airways under varying conditions of inflammation and along the proximal-distal axis. Methods: Lung tissue was obtained from mice stimulated to upregulate mucin production by the cytokines IL-1β and IL-13 or by porcine pancreatic elastase. Human lung tissue was obtained from donated normal lungs, biopsy samples of transplanted lungs, and explanted lungs from subjects with chronic obstructive pulmonary disease. MUC5AC and MUC5B were labeled with antibodies from different animal species or, in mice only, by transgenic chimeric mucin-fluorescent proteins and imaged using widefield deconvolution or Airyscan fluorescence microscopy. Measurements and Main Results: In both mouse and human airways, most secretory granules contained both mucins interdigitating within the granules. Smaller numbers of granules contained MUC5B alone, and even fewer contained MUC5AC alone. Conclusions: MUC5AC and MUC5B are variably stored both in the same and in separate secretory granules of both mice and humans. The high fraction of granules containing both mucins under a variety of conditions makes it unlikely that their secretion can be differentially controlled as a therapeutic strategy. This work also advances knowledge of the packaging of mucins within secretory granules to understand mechanisms of epithelial stress in the pathogenesis of chronic lung diseases.

Analysis of starch structure and functional properties of tetraploid wheat (Triticum turgidum L.) with differing waxy protein composition.

An increased demand for food has mirrored the increasing global population. Obesity and diabetes are two disorders induced by poor eating choices. Consequently, there is an urgent need to develop modified foods that can ameliorate such illnesses. The objective of this study was to explore the effect of Waxy genes on the structural and functional properties of starch, with the aim of improving food quality. Wild-type tetraploid wheat was compared with three mutants with different Waxy gene combinations. The proportion of B-type granules was higher in the mutants than in the wild-type (Wx-AB), and there were significant changes in the starch granule size, number, and phenotype in the Wx free mutant (Wx-ab). The lowest branch chain length was observed in Wx-ab, whereas Wx-AB had the highest branch chain length of DP ≥ 37. Wx-ab had the highest degree of crystallinity. The crystallinity trend followed the order Wx-ab>Wx-Ab>Wx-aB>Wx-AB. The amount of slowly digestible starch (SDS) was higher in native, gelatinized, and retrograded starch in the mutant. The amount of retrograded starch was closer to gelatinized starch than to native starch. Waxy proteins make a substantial contribution to starch structure. A lack of waxy proteins reduced the unit chains markedly compared with the control. Waxy proteins significantly affected the smaller and longer chains of starch. The lines with differing waxy composition had different effects on food digestion. The Wx-AB in native starch and Wx-Ab in gelatinized starch can control obesity and diabetes by slow-digesting carbohydrates and high resistance to digestion. © 2022 Society of Chemical Industry.

Identification of embryonic RNA granules that act as sites of mRNA translation after changing their physical properties

SummaryFertilized eggs begin to translate mRNAs at appropriate times and placements to control development, but how the translation is regulated remains unclear. Here, we found that pou5f3 mRNA encoding a transcriptional factor essential for development formed granules in a dormant state in zebrafish oocytes. Although the number of pou5f3 granules remained constant, Pou5f3 protein accumulated after fertilization. Intriguingly, signals of newly synthesized peptides and a ribosomal protein became colocalized with pou5f3 granules after fertilization and, moreover, nascent Pou5f3 was shown to be synthesized in the granules. This functional change was accompanied by changes in the state and internal structure of granules. Dissolution of the granules reduced the rate of protein synthesis. Similarly, nanog and sox19b mRNAs in zebrafish and Pou5f1/Oct4 mRNA in mouse assembled into granules. Our results reveal that subcellular compartments, termed embryonic RNA granules, function as activation sites of translation after changing physical properties for directing vertebrate development.

Role of Stress Granules in the Pathogenesis of Pulmonary Hypertension Kosmas Kosmas 1,2, Fotios Spyropoulos1,2,Helen Christou 1,21Department of Pediatric Newborn Medicine, Brigham and Women’s Hospital, Boston, MA 02115, USA 2Harvard Medical School, Boston, MA 02215, USA

BackgroundPAH is a devastating and incurable disease characterized by abnormal pulmonary vascular phenotypes and progressive right ventricular failure, but the underlying mechanisms are incompletely understood. There is an urgent need of new therapeutic approaches, and a better understanding of disease pathogenesis is essential in identifying novel pathways that can be therapeutically targeted. Stress granules (SGs) are small intracellular structures that form in response to stress and contain mRNA molecules and mRNA‐binding proteins. These granules allow cells to temporarily halt translation by “parking” or sequestering certain mRNAs in a protected zone (the stress granule) and this allows the cells to survive in conditions of stress. The role of SGs in abnormal vascular and cardiac homeostasis in PAH is not known.HypothesesWe hypothesized that increased SG formation may contribute to both abnormal vascular cellular phenotypes and cardiac failure in human and experimental PAH. Further, we examined whether treatment with the carbonic anhydrase Acetazolamide (ACTZ) which is known to ameliorate experimental PAH, would alter SG tissue abundance in the lungs and heart.MethodsWe used the adult rat (Sprague Dawley) sugen/hypoxia (Su/Hx) model of severe pulmonary hypertension and studied tissue sections from lungs, heart and skeletal muscle as well as isolated primary pulmonary artery smooth muscle cells (PASMCs). We also used PASMCs from patients with PAH. We applied a combination of immunofluorescence and protein expression studies as well as drug (ACTZ) treatment and in vitro induction of oxidative stress (arsenite) to assess SG formation and SG related markers in experimental PAH and the effect of ACTZ.ResultsWe have discovered that PASMCs from patients with PAH have a higher number of stress granules in response to oxidative stress than cells from normal individuals. We also found that PASMCs from a preclinical model of PAH (Sugen/Hypoxia) have more stress granules and increased SG components in response to oxidative stress compared to normal animals. Further, we found that treatment of PASMCs with ACTZ resulted in lower number of stress granules after cell stress. In addition, we found increased G3BP1 (key component of SG assembly) puncta in alveoli and bronchi and sarcoplasmic G3BP1 puncta in cardiac and soleus muscles from the rat sugen/hypoxia (Su/Hx) model compared to controls and with ACTZ treatment.ConclusionsWe conclude that there is increased SG formation in PASMCs and tissues in experimental PAH and acetazolamide inhibits stress granule assembly in response to oxidative stress. Further studies are needed to define the role of SG in disease pathogenesis, and evaluate whether targeting stress granules may be effective in restoring normal cellular function and improving PAH.

The Impact of Profilin‐1 Mutations on Protein Homeostasis in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive, fatal disease characterized by the dysfunction and degeneration of motor neurons in the central nervous system. ALS has been linked to a number of genetic mutations, including point mutations in the actin‐binding protein profilin‐1 (Pfn1). While the prevalence of Pfn1 mutations is low, around 1% of inherited forms of the disease, an understanding of their impact on motor neuron cell death can provide insight into the mechanisms underlying ALS onset and progression. As Pfn1 is an important regulator of the actin cytoskeleton, we hypothesize that ALS‐linked mutations of Pfn1 promote defects in protein homeostasis and synaptic communication. To test this hypothesis, neuronal cells were transfected with Pfn1 constructs (including wild‐type, C71G, and M118V) and subjected to cellular stressors (including heat shock and sodium arsenite treatments). Immunostaining was then used to visualize and quantify differences in protein aggregation and stress granule formation. Our results have established the baseline response with the wild‐type construct and indicate that there is an increase in protein aggregation as well as in the number and size of stress granules with the mutant constructs. Our ongoing studies are aimed at validating these preliminary results, and our goal is to provide mechanistic insight pertaining to Pfn1’s role in ALS disease pathogenesis.

On Information Granulation via Data Clustering for Granular Computing-Based Pattern Recognition: A Graph Embedding Case Study

Granular Computing is a powerful information processing paradigm, particularly useful for the synthesis of pattern recognition systems in structured domains (e.g., graphs or sequences). According to this paradigm, granules of information play the pivotal role of describing the underlying (possibly complex) process, starting from the available data. Under a pattern recognition viewpoint, granules of information can be exploited for the synthesis of semantically sound embedding spaces, where common supervised or unsupervised problems can be solved via standard machine learning algorithms. In this work, we show a comparison between different strategies for the automatic synthesis of information granules in the context of graph classification. These strategies mainly differ on the specific topology adopted for subgraphs considered as candidate information granules and the possibility of using or neglecting the ground-truth class labels in the granulation process. Computational results on 10 different open-access datasets show that by using a class-aware granulation, performances tend to improve (regardless of the information granules topology), counterbalanced by a possibly higher number of information granules.

Two-Pore Channels Regulate Inter-Organellar Ca2+ Homeostasis in Immune Cells.

Two-pore channels (TPCs) are ligand-gated cation-selective ion channels that are preserved in plant and animal cells. In the latter, TPCs are located in membranes of acidic organelles, such as endosomes, lysosomes, and endolysosomes. Here, we focus on the function of these unique ion channels in mast cells, which are leukocytes that mature from myeloid hematopoietic stem cells. The cytoplasm of these innate immune cells contains a large number of granules that comprise messenger substances, such as histamine and heparin. Mast cells, along with basophil granulocytes, play an essential role in anaphylaxis and allergic reactions by releasing inflammatory mediators. Signaling in mast cells is mainly regulated via the release of Ca2+ from the endoplasmic reticulum as well as from acidic compartments, such as endolysosomes. For the crosstalk of these organelles TPCs seem essential. Allergic reactions and anaphylaxis were previously shown to be associated with the endolysosomal two-pore channel TPC1. The release of histamine, controlled by intracellular Ca2+ signals, was increased upon genetic or pharmacologic TPC1 inhibition. Conversely, stimulation of TPC channel activity by one of its endogenous ligands, namely nicotinic adenine dinucleotide phosphate (NAADP) or phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), were found to trigger the release of Ca2+ from the endolysosomes; thereby improving the effect of TPC1 on regulated mast cell degranulation. In this review we discuss the importance of TPC1 for regulating Ca2+ homeostasis in mast cells and the overall potential of TPC1 as a pharmacological target in anti-inflammatory therapy.

Combined Effect of Nitrogen Fertilizer Application and High Temperature on Grain Quality Properties of Cooked Rice.

Ambient temperature and nitrogen (N) fertilizer are two of the most important factors that affect rice grain quality. However, less information has been available on the interactive effect of N fertilizer and ambient temperature on grain quality under stressful high temperature (HT). In this article, the effects of panicle N fertilizer, ambient temperature, and their interaction on starch composition, particle size distribution of starch granules, starch physicochemical properties, and storage protein accumulation in milled grains were investigated to clarify the potential role of panicle N fertilizer topdressing in regulating rice grain quality under stressful HT by using a two-factor experiment of three N levels in combination with two temperature regimes. Results showed that appropriate application of panicle N fertilizer could attenuate the adverse effect of HT during grain filling on milling quality and chalky occurrence to some extent, particularly for the effective alleviation of HT-induced decrease in milling quality. However, the topdressing of panicle N fertilizer tended to enhance starch gelatinization enthalpy (ΔH) and its setback viscosity in HT-ripening grains, with the simultaneous decrements in the number and surface area proportions of smaller starch granules under the higher N fertilizer in combination with HT exposure. The effects of higher nitrogen fertilizer and HT exposure on total protein content and gluten composition of grains were additively increased. Hence, the topdressing of panicle N fertilizer exacerbated HT-induced deterioration in cooking and eating quality, rather than alleviating the negative impact of HT exposure on the palatability of cooked rice.

Wheat E3 ubiquitin ligase TaGW2-6A degrades TaAGPS to affect seed size

TaGW2 has been identified as a key determinant of the grain weight in wheat (Triticum aestivum L.). In our previous study, we found that the grain size differs in Chinese Spring (CS) and its TaGW2-6A allelic variant (NIL31). In addition, the expression of the key starch biosynthesis enzyme gene TaAGPS differs significantly in the two materials. However, the underlying molecular mechanism associated with the action of TaGW2-6A has not been reported. In the present study, we found that TaGW2-6A-CS interacted with TaAGPS, whereas TaGW2-6A-NIL31 did not interact with it in vitro and in vivo. Furthermore, we found that the C-terminal LXLX domain (376–424 aa) of TaGW2-6A recognized TaAGPS. However, the TaGW2-6A allelic variant lacked this key interaction region due to premature translation termination. We also found that TaGW2-6A-CS can ubiquitinate TaAGPS and degrade it via the 26 S proteasome pathway. In addition, our analysis of the activity of ADP-glucose pyrophosphorylase (AGPase) indicated that the AGPase level in the endosperm cells was lower in CS than NIL31. Cytological observations demonstrated that the average number of starch granules and the average area of starch granules in endosperm cells were lower in CS than NIL31. The overexpression of TaAGPS positively regulated the seed size in transgenic Arabidopsis. Our findings provide novel insights into the molecular mechanism that allows TaGW2-6A-TaAGPS to regulate seed size via the starch synthesis pathway.

Carbon pathways during transitory starch degradation in Arabidopsis differentially affect the starch granule number and morphology in the dpe2/phs1 mutant background

The Arabidopsis knockout mutant lacking both the cytosolic disproportionating enzyme 2 (DPE2) and the plastidial phosphorylase (PHS1) had a dwarf-growth phenotype, a reduced and uneven distribution of starch within the plant rosettes, and a lower starch granule number per chloroplast under standard growth conditions. In contrast, a triple mutant impaired in starch degradation by its additional lack of the glucan, water dikinase (GWD) showed improved plant growth, a starch-excess phenotype, and a homogeneous starch distribution. Furthermore, the number of starch granules per chloroplast was increased and was similar to the wild type. We concluded that ongoing starch degradation is mainly responsible for the observed phenotype of dpe2/phs1. Next, we generated two further triple mutants lacking either the phosphoglucan, water dikinase (PWD), or the disproportionating enzyme 1 (DPE1) in the background of the double mutant. Analysis of the starch metabolism revealed that even minor ongoing starch degradation observed in dpe2/phs1/pwd maintained the double mutant phenotype. In contrast, an additional blockage in the glucose pathway of starch breakdown, as in dpe2/phs1/dpe1, resulted in a nearly starch-free phenotype and massive chloroplast degradation. The characterized mutants were discussed in the context of starch granule formation.

The Effect of Nitrogen Fertilizer on Rhizome Quality and Starch Physicochemical Properties in Nelumbo nucifera

Optimal nitrogen (N) supply significantly increases the starch content, components, and yield of Nelumbo nucifera. However, the underlying transcriptional mechanism and starch accumulation under dose-dependent nitrogen fertilizer are poorly understood. In this study, we found that the optimal nitrogen fertilizer (N2, 30 kg/667 m2) was more beneficial to improve the stomatal conductance (Gs), leaf intercellular CO2 concentration (Ci), transpiration rate (Tr), net photosynthetic rates (Pn), chlorophyll content, starch content, and plot yield. What is more, N2-fertilizer treatment induced a higher number of starch granule, AP2 content, and RVA curve peaks. Then, the transcriptomic analyses performed in control (CK) and N2-fertilizer treatment (N2) showed that the expressions of many differentially expressed genes (DEGs) were significantly induced by N2. KEGG and GO enrichment analysis showed that these DEGs were significantly enriched in biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, carbon metabolism, carbon fixation in photosynthetic organisms, plant hormone signal transduction, and starch and sucrose metabolisms, suggesting that nitrogen fertilizer induced alterations of photosynthesis- and starch accumulation-related gene expression profiles. Finally, six photosynthesis-related genes and fourteen starch synthesis-related genes were confirmed to be required for starch accumulation in the Nelumbo nucifera development. qPCR analysis of six starch accumulation-related genes demonstrated the accuracy of the transcriptome. Hence, our study provides valuable resource for future studies on molecular mechanisms underlying starch accumulation in Nelumbo nucifera rhizome under N-fertilizer treatment.

Molecular mechanism of nutrient uptake in developing embryos of oviparous cloudy catshark (Scyliorhinus torazame).

Forms of embryonic nutrition are highly diverse in cartilaginous fishes, which contain oviparity, yolk-sac viviparity and several types of matrotrophic viviparity (histotrophy, oophagy, and placentotrophy). The molecular mechanisms of embryonic nutrition are poorly understood in these animals as few species are capable of reproducing in captivity. Oviparous cartilaginous fishes solely depend on yolk nutrients for their growth and development. In the present study, we compared the contribution to embryonic nutrition of the embryonic intestine with the yolk sac membrane (YSM). RNA-seq analysis was performed on the embryonic intestine and YSM of the oviparous cloudy catshark Scyliorhinus torazame to identify candidate genes involved in nutrient metabolism to further the understanding of nutrient utilization of developing embryos. RNA-seq discovery was subsequently confirmed by quantitative PCR analysis and we identified increases in several amino acid transporter genes (slc3a1, slc6a19, slc3a2, slc7a7) as well as genes involved in lipid absorption (apob and mtp) in the intestine after ‘pre-hatching’, which is a developmental event marked by an early opening of the egg case about 4 months before hatching. Although a reciprocal decrease in the nutritional role of YSM was expected after the intestine became functional, we observed similar increases in gene expression among amino acid transporters, lipid absorption molecules, and lysosomal cathepsins in the extraembryonic YSM in late developmental stages. Ultrastructure of the endodermal cells of YSM showed that yolk granules were incorporated by endocytosis, and the number of granules increased during development. Furthermore, the digestion of yolk granules in the YSM and nutrient transport through the basolateral membrane of the endodermal cells appeared to be enhanced after pre-hatching. These findings suggest that nutrient digestion and absorption is highly activated in both intestine and YSM after pre-hatching in catshark embryos, which supports the rapid growth at late developmental stages.