Development of bundle sheath chloroplasts in rice seedlings

1976 ◽  
Vol 54 (7) ◽  
pp. 556-565 ◽  
Author(s):  
Hiroshi Miyake ◽  
Eizo Maeda
Keyword(s):  
Leaf Development ◽  
Chloroplast Development ◽  
Developmental Process ◽  
Bundle Sheath ◽  
Rice Seedlings ◽  
Early Stages ◽  
Late Stages ◽  
Storage Starch

A developmental process of bundle sheath chloroplasts in rice seedlings is examined and compared with that of mesophyll chloroplasts. Chloroplast development is accompanied with the leaf development. Both types of chloroplasts accumulate starch derived from endosperm in the early stages of the leaf development, and the accumulated starch is dissipated during the leaf development. In contrast with mesophyll chloroplasts, bundle sheath chloroplasts accumulate large amounts of starch, appear as spherical, amyloplast-like structures, and preserve the starch up to the late stages of the leaf development. It is suggested that bundle sheath chloroplasts of rice seedlings are specialized in the accumulation and supply of storage starch, which is presumed to be consumed for the leaf development.

Starch accumulation in bundle sheath chloroplasts during the leaf development of C3 and C4 plants of the Gramineae

1978 ◽  
Vol 56 (7) ◽  
pp. 880-882 ◽  
Author(s):  
Hiroshi Miyake ◽  
Eizo Maeda
Keyword(s):  
Oryza Sativa ◽  
Light Microscopy ◽  
Leaf Development ◽  
Cynodon Dactylon ◽  
Bundle Sheath ◽  
Starch Accumulation ◽  
Phragmites Communis ◽  
C3 And C4 Plants ◽  
Bundle Sheath Cells ◽  
Storage Starch

Nonphotosynthetic starch accumulation in chloroplasts is examined by light microscopy during the leaf development of several C3 and C4 grasses and compared between mesophyll and bundle sheath cells. In Oryza sativa, Phragmites communis (C3 grasses), and Cynodon dactylon (C4 grass), bundle sheath chloroplasts accumulate large amounts of starch in the early stages of the leaf development, while in other grasses, both mesophyll and bundle sheath chloroplasts accumulate only small amounts of starch. It is suggested that bundle sheath chloroplasts of starch-accumulating species, regardless of their photosynthetic characteristics, are specialized in the accumulation and supply of storage starch during the leaf development.

scholarly journals Plastid-Localized EMB2726 Is Involved in Chloroplast Biogenesis and Early Embryo Development in Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Chuanling Li ◽  
Jian-Xiu Shang ◽  
Chenlei Qiu ◽  
Baowen Zhang ◽  
Jinxue Wang ◽  
...  
Keyword(s):  
Chloroplast Development ◽  
Developmental Process ◽  
Higher Plants ◽  
Critical Role ◽  
Elongation Factor ◽  
Early Embryo ◽  
The Body ◽  
Insertion Mutant ◽  
Cell Stage ◽  
Dna Insertion

Embryogenesis is a critical developmental process that establishes the body organization of higher plants. During this process, the biogenesis of chloroplasts from proplastids is essential. A failure in chloroplast development during embryogenesis can cause morphologically abnormal embryos or embryonic lethality. In this study, we isolated a T-DNA insertion mutant of the Arabidopsis gene EMBRYO DEFECTIVE 2726 (EMB2726). Heterozygous emb2726 seedlings produced about 25% albino seeds with embryos that displayed defects at the 32-cell stage and that arrested development at the late globular stage. EMB2726 protein was localized in chloroplasts and was expressed at all stages of development, such as embryogenesis. Moreover, the two translation elongation factor Ts domains within the protein were critical for its function. Transmission electron microscopy revealed that the cells in emb2726 embryos contained undifferentiated proplastids and that the expression of plastid genome-encoded photosynthesis-related genes was dramatically reduced. Expression studies of DR5:GFP, pDRN:DRN-GFP, and pPIN1:PIN1-GFP reporter lines indicated normal auxin biosynthesis but altered polar auxin transport. The expression of pSHR:SHR-GFP and pSCR:SCR-GFP confirmed that procambium and ground tissue precursors were lacking in emb2726 embryos. The results suggest that EMB2726 plays a critical role during Arabidopsis embryogenesis by affecting chloroplast development, possibly by affecting the translation process in plastids.

IFITM proteins that restrict the early stages of respiratory virus infection do not influence late-stage replication

2021 ◽  
Author(s):  
Tina Meischel ◽  
Svenja Fritzlar ◽  
Fernando Villalon-Letelier ◽  
Melkamu B. Tessema ◽  
Andrew G. Brooks ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Antiviral Activity ◽  
Influenza A ◽  
Respiratory Viruses ◽  
Parainfluenza Virus ◽  
Early Stages ◽  
Infected Cells ◽  
Cellular Entry ◽  
Overexpression System ◽  
Late Stages

Interferon-induced transmembrane (IFITM) proteins inhibit a broad range of enveloped viruses by blocking entry into host cells. We used an inducible overexpression system to investigate if IFITM1, IFITM2 and IFITM3 could modulate early and/or late stages of influenza A virus (IAV) or parainfluenza virus (PIV)-3 infection in human A549 airway epithelial cells. IAV and PIV-3 represent respiratory viruses which utilise distinct cellular entry pathways. We verify entry by endocytosis for IAV, whereas PIV-3 infection was consistent with fusion at the plasma membrane. Following induction prior to infection, all three IFITM proteins restricted the percentage of IAV-infected cells at 8 hours post-infection. In contrast, prior induction of IFITM1 and IFITM2 did not inhibit PIV-3 infection, although a modest reduction was observed with IFITM3. siRNA-mediated knockdown of endogenous IFITM1, IFITM2 and IFITM3 expression, in the presence or absence of pre-treatment with type I interferon, resulted in increased IAV, but not PIV-3, infection. This suggests that while all three IFITMs display antiviral activity against IAV, they do not restrict the early stages of PIV-3 infection. IAV and PIV-3 infection culminates in viral egress through budding at the plasma membrane. Inducible expression of IFITM1, IFITM2 or IFITM3 immediately after infection did not impact titres of infectious virus released from IAV or PIV-3 infected cells. Our findings show that IFITM proteins differentially restrict the early stages of infection of two respiratory viruses with distinct cellular entry pathways, but do not influence the late stages of replication for either virus. IMPORTANCE Interferon-induced transmembrane (IFITM) proteins restrict the initial stages of infection for several respiratory viruses, however their potential to modulate the later stages of virus replication has not been explored. In this study we highlight the utility of an inducible overexpression system to assess the impact of IFITM proteins on either early or late stage replication of two respiratory viruses. We demonstrate antiviral activity by IFITM1, IFITM2 and IFITM3 against influenza A virus (IAV) but not parainfluenza virus (PIV)-3 during the early stages of cellular infection. Furthermore, IFITM induction following IAV or PIV-3 infection does not restrict the late stages of replication of either virus. Our findings show that IFITM proteins can differentially restrict the early stages of infection of two viruses with distinct cellular entry pathways, yet do not influence the late stages of replication for either virus.

Growth and Differentiation of Transplanted W/Wv Marrow

Blood ◽  
1967 ◽  
Vol 30 (5) ◽  
pp. 601-616 ◽  
Author(s):  
JERRY P. LEWIS ◽  
LOIS F. O’GRADY ◽  
SELDON E. BERNSTEIN ◽  
ELIZABETH S. RUSSELL ◽  
FRANK E. TROBAUGH
Keyword(s):  
Macrocytic Anemia ◽  
Severe Anemia ◽  
Early Stages ◽  
Erythroid Precursors ◽  
Erythroid Maturation ◽  
Reduced Rate ◽  
Immature Cells ◽  
Erythroid Development ◽  
Mutant Genes ◽  
Late Stages

Abstract This paper reports new data on the effect of the action of the mutant genes W and Wv on murine hemopoiesis. Our studies demonstrate that the presence of these mutant genes produces: (1) a macrocytic anemia with neither granulocytopenia nor thrombocytopenia; (2) a severe defect in the early stages of hemopoietic repopulation manifested by (a) an apparent block in the differentiation of immature cells into erythroid precursors, and (b) a greatly reduced rate of proliferation of differentiated hemopoietic elements. These data demonstrate the existence of genetic influence on repopulation and differentiation of transplanted marrow and suggest that severe anemia may result not only from defects in the late stages of erythroid development but also from abnormalities in the early stages of erythroid maturation and hemopoietic repopulation.

scholarly journals NEPHRITIS AND ITS INFLUENCE UPON HEMOGLOBIN PRODUCTION IN EXPERIMENTAL ANEMIA

1939 ◽  
Vol 69 (4) ◽  
pp. 485-498 ◽  
Author(s):  
G. H. Whipple ◽  
F. S. Robscheit-Robbins
Keyword(s):  
Early Stages ◽  
Late Stages ◽  
Hemoglobin Production

Spontaneous glomerulonephritis develops not infrequently (11 per cent incidence) in the anemia colony. The course of the nephritis is insidious and usually extends over several years but ends in uremia, often with terminal bronchopneumonia. Hemoglobin production in these standard anemic dogs is well established as related to various standard food factors. These tests are summarized in the tables above to show the changes that appear year by year in the life of each dog. Nephritis causes little or no change in hemoglobin production in anemic dogs in the early stages of the disease. In the late stages of nephritis there may be no change or moderate changes in hemoglobin production in these anemic dogs. The average is 70 per cent of normal hemoglobin production in advanced nephritis. It seems unlikely that this degree of impairment of hemoglobin production in nephritis would result in spontaneous anemia in the dog.

scholarly journals Cohesion of Sister Chromosome Termini during the Early Stages of Sporulation in Bacillus subtilis

2020 ◽  
Vol 202 (20) ◽  
Author(s):  
Clare Willis ◽  
Jeff Errington ◽  
Ling Juan Wu
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Mother Cell ◽  
Developmental Process ◽  
Time Lapse ◽  
Axial Filament ◽  
Content Type ◽  
Early Stages ◽  
Cell Compartments ◽  
Sister Chromosome

ABSTRACT During sporulation of Bacillus subtilis, the cell cycle is reorganized to generate separated prespore and mother cell compartments, each containing a single fully replicated chromosome. The process begins with reorganization of the nucleoid to form an elongated structure, the axial filament, in which the two chromosome origins are attached to opposite cell poles, with the remainder of the DNA stretched between these sites. When the cell then divides asymmetrically, the division septum closes around the chromosome destined for the smaller prespore, trapping the origin-proximal third of the chromosome in the prespore. A translocation pore is assembled through which a DNA transporter, SpoIIIE/FtsK, transfers the bulk of the chromosome to complete the segregation process. Although the mechanisms involved in attaching origin regions to the cell poles are quite well understood, little is known about other aspects of axial filament morphology. We have studied the behavior of the terminus region of the chromosome during sporulation using time-lapse imaging of wild-type and mutant cells. The results suggest that the elongated structure involves cohesion of the terminus regions of the sister chromosomes and that this cohesion is resolved when the termini reach the asymmetric septum or translocation pore. Possible mechanisms and roles of cohesion and resolution are discussed. IMPORTANCE Endospore formation in Firmicutes bacteria provides one of the most highly resistant life forms on earth. During the early stages of endospore formation, the cell cycle is reorganized so that exactly two fully replicated chromosomes are generated, before the cell divides asymmetrically to generate the prespore and mother cell compartments that are critical for the developmental process. Decades ago, it was discovered that just prior to asymmetrical division the two chromosomes enter an unusual elongated configuration called the axial filament. This paper provides new insights into the nature of the axial filament structure and suggests that cohesion of the normally separated sister chromosome termini plays an important role in axial filament formation.

scholarly journals Three-dimensional analysis of synaptic organization in the hippocampal CA1 field in Alzheimer’s disease

Brain ◽  
2020 ◽  
Author(s):  
Marta Montero-Crespo ◽  
Marta Domínguez-Álvaro ◽  
Lidia Alonso-Nanclares ◽  
Javier DeFelipe ◽  
Lidia Blazquez-Llorca
Keyword(s):  
Electron Microscopy ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Β ◽  
Cortical Atrophy ◽  
Structural Basis ◽  
Synaptic Organization ◽  
Synaptic Density ◽  
Early Stages ◽  
Late Stages

Abstract Alzheimer’s disease is the most common form of dementia, characterized by a persistent and progressive impairment of cognitive functions. Alzheimer’s disease is typically associated with extracellular deposits of amyloid-β peptide and accumulation of abnormally phosphorylated tau protein inside neurons (amyloid-β and neurofibrillary pathologies). It has been proposed that these pathologies cause neuronal degeneration and synaptic alterations, which are thought to constitute the major neurobiological basis of cognitive dysfunction in Alzheimer’s disease. The hippocampal formation is especially vulnerable in the early stages of Alzheimer’s disease. However, the vast majority of electron microscopy studies have been performed in animal models. In the present study, we performed an extensive 3D study of the neuropil to investigate the synaptic organization in the stratum pyramidale and radiatum in the CA1 field of Alzheimer’s disease cases with different stages of the disease, using focused ion beam/scanning electron microscopy (FIB/SEM). In cases with early stages of Alzheimer’s disease, the synapse morphology looks normal and we observed no significant differences between control and Alzheimer’s disease cases regarding the synaptic density, the ratio of excitatory and inhibitory synapses, or the spatial distribution of synapses. However, differences in the distribution of postsynaptic targets and synaptic shapes were found. Furthermore, a lower proportion of larger excitatory synapses in both strata were found in Alzheimer’s disease cases. Individuals in late stages of the disease suffered the most severe synaptic alterations, including a decrease in synaptic density and morphological alterations of the remaining synapses. Since Alzheimer’s disease cases show cortical atrophy, our data indicate a reduction in the total number (but not the density) of synapses at early stages of the disease, with this reduction being much more accentuated in subjects with late stages of Alzheimer’s disease. The observed synaptic alterations may represent a structural basis for the progressive learning and memory dysfunctions seen in Alzheimer’s disease cases.

Larval morphology of Dart-Poison Frogs (Anura: Dendrobatoidea: Aromobatidae and Dendrobatidae)

Zootaxa ◽  
2013 ◽  
Vol 3637 (5) ◽  
pp. 569 ◽  
Author(s):  
DAVID A. SÁNCHEZ
Keyword(s):  
Digestive System ◽  
Larval Morphology ◽  
Stages Of Development ◽  
Taxonomic Assignment ◽  
Digestive Tube ◽  
Early Stages ◽  
Constant Diameter ◽  
The Family ◽  
Upper Jaw ◽  
Late Stages

Tadpoles in the superfamily Dendrobatoidea (families Aromobatidae and Dendrobatidae), housed in zoological collections or illustrated in publications, were studied. For the most part, tadpoles of species within the family Aromobatidae, the subfamilies Colostethinae and Hyloxalinae (of the family Dendrobatidae), and those of the genus Phyllobates, Dendrobatinae (Dendrobatidae) have slender anterior jaw sheaths with a medial notch and slender lateral processes, triangular fleshy projections on the inner margin of the nostrils and digestive tube with constant diameter and color and its axis sinistrally directed, concealing the liver and other organs. These morphologies are different from the ones observed in tadpoles of species included in the Dendrobatinae (minus Phyllobates). Exceptions to these morphological arrangements are noted, being the digestive system arrangement and the nostril ornamentation more plastic than the shape of the upper jaw sheath. Tadpoles of all species of the Dendrobatoidea have similar disposition of digestive organs in early stages, but differentiate in late stages of development. Classifying the upper jaw sheath into the two recognized states is possible from very early stages of development, but gut disposition and nostril ornamentation cannot be determined until late in development, making classification and taxonomic assignment of tadpoles based on these morphological features challenging.

The effect of novel small molecule drugs in human explants across the disease sequence in colorectal cancer.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. e13570-e13570
Author(s):  
Adrian Gerard Murphy ◽  
Rory Casey ◽  
David William Fennelly ◽  
Alison Reynolds ◽  
Miriam Tosetto ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Ex Vivo ◽  
Survival Rates ◽  
Colorectal Tumor ◽  
Preclinical Development ◽  
Zebrafish Larvae ◽  
Early Stages ◽  
Late Stages ◽  
Human Explants ◽  
Tnf Secretion

e13570 Background: The treatment of metastatic colorectal cancer has been improved by combining cytotoxic chemotherapy with bevacizumab. Newer anti-angiogenic agents are required to improve survival rates as response rates with the current therapies are modest. The preclinical development of such drugs is time-consuming and new methods are required to test the efficacy of lead drugs which represent the entire tumor micro-environment. Methods: Chemical screens were performed in zebrafish larvae to identify hits that affected intersegmental angiogenesis. Five lead drugs were then tested for cytotoxicity using the crystal violet assay. These drugs were tested using ex vivo colorectal tumor explants to determine their effect on secretion of IL-1β, TNF, IL-6 and VEGF. Human explants from 20 patients (Dukes A-D) were cultured for 72 hours and the levels of the above factors measured by ELISA. Comparisons were made between early (Dukes A&B) and late stages (Dukes C&D). Results: One thousand drugs were screened and 5 were found to reduce intersegmental angiogenesis in zebrafish larvae: AM1, AM2, AM3, AM4 and AM5. The drugs did not affect cell growth levels at 10 µM concentration. From the explant studies: AM1 decreased secretion of VEGF in late stages (p=0.005) and IL-6 in early stages (p=0.009). AM2 decreased VEGF in early (p=0.004) and late stages (p=0.02). AM3 decreased TNF secretion in late stages (p=0.02) and IL-6 secretion in early (p=0.009) and late stages (p<0.0001). AM4 decreased VEGF secretion in early stages (p=0.001), IL-6 in early stages (p<0.001) and late stages (p=0.03) and IL-1β in early stages (p=0.002). AM5 decreased IL-6 secretion in the early stages (p=0.03) and IL-1β in the early stages (p=0.001).Overall, IL-1β secretion was reduced by AM4, AM3 and AM5 (p<0.05). IL-6 secretion was reduced by AM1, AM3 and AM4 (p=0.001). TNF secretion was reduced by AM3 (p=0.02) and VEGF secretion was reduced by AM1, AM2 and AM4 (p<0.005). Conclusions: These studies show these drugs have stage-specific effects in colorectal tumor explants and may have the potential as new anti-angiogenic agents in colorectal cancer.

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