Normal differentiation patterns in plants lacking microtubular preprophase bands

Nature ◽  
1995 ◽  
Vol 375 (6533) ◽  
pp. 676-677 ◽  
Author(s):  
Jan Traas ◽  
Catherine Bellini ◽  
Philippe Nacry ◽  
Jocelyne Kronenberger ◽  
David Bouchez ◽  
...  
Keyword(s):  
Normal Differentiation ◽  
Preprophase Bands

DNA replication and the development of preprophase bands in soybean protoplast cultures

1991 ◽  
Vol 82 (2) ◽  
pp. 150-156 ◽  
Author(s):  
Hong Wang ◽  
Adrian J. Cutler ◽  
Larry C. Fowke
Keyword(s):  
Dna Replication ◽  
Preprophase Bands

discordia mutations specifically misorient asymmetric cell divisions during development of the maize leaf epidermis

Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4623-4633 ◽  
Author(s):  
K. Gallagher ◽  
L.G. Smith
Keyword(s):  
Cell Division ◽  
Preprophase Band ◽  
Cytochalasin D ◽  
Leaf Epidermis ◽  
Asymmetric Cell Divisions ◽  
Maize Leaf ◽  
Cell Divisions ◽  
Cytoskeletal Structure ◽  
Dividing Cells ◽  
Preprophase Bands

In plant cells, cytokinesis depends on a cytoskeletal structure called a phragmoplast, which directs the formation of a new cell wall between daughter nuclei after mitosis. The orientation of cell division depends on guidance of the phragmoplast during cytokinesis to a cortical site marked throughout prophase by another cytoskeletal structure called a preprophase band. Asymmetrically dividing cells become polarized and form asymmetric preprophase bands prior to mitosis; phragmoplasts are subsequently guided to these asymmetric cortical sites to form daughter cells of different shapes and/or sizes. Here we describe two new recessive mutations, discordia1 (dcd1) and discordia2 (dcd2), which disrupt the spatial regulation of cytokinesis during asymmetric cell divisions. Both mutations disrupt four classes of asymmetric cell divisions during the development of the maize leaf epidermis, without affecting the symmetric divisions through which most epidermal cells arise. The effects of dcd mutations on asymmetric cell division can be mimicked by cytochalasin D treatment, and divisions affected by dcd1 are hypersensitive to the effects of cytochalasin D. Analysis of actin and microtubule organization in these mutants showed no effect of either mutation on cell polarity, or on formation and localization of preprophase bands and spindles. In mutant cells, phragmoplasts in asymmetrically dividing cells are structurally normal and are initiated in the correct location, but often fail to move to the position formerly occupied by the preprophase band. We propose that dcd mutations disrupt an actin-dependent process necessary for the guidance of phragmoplasts during cytokinesis in asymmetrically dividing cells.

scholarly journals Differential Effects of IL-2 and IL-6 on the Development of Three Distinct Precursor T-Cell Populations in the Thymus

1990 ◽  
Vol 1 (2) ◽  
pp. 77-84 ◽  
Author(s):  
Naoko Nakano ◽  
Hitoshi Kikutani ◽  
Tadamitsu Kishimoto
Keyword(s):  
Bone Marrow ◽  
T Cell ◽  
Bone Marrow Cells ◽  
Cell Populations ◽  
High Dose ◽  
Transfer System ◽  
Cell Sorter ◽  
Lineage Markers ◽  
Low Levels ◽  
Normal Differentiation

Three distinct T-cell precursors: bone marrow cells that express low levels of the Thy-1 antigen but no lineage markers (Thy-1-lo/BM); CD4-, CD8-, and CD3-thymocytes that express low levels of the Thy-1 antigen (Thy-1-lo/Thym); and CD4-, CD8-, and CD3-thymocytes that express high levels of the Thy-1 antigen and the IL-2 Rαchain (Thy-1+/ IL2R+) were isolated by fluorescence-activated cell sorter (FACS). These three populations expanded with different kinetics in the thymus of irradiated recipient mice after intrathymic transfer. When a high dose of human recombinant IL-2 (r-IL-2) or human recombinant IL-6 (r-IL-6) was administered, r-IL-6 accelerated donor Thy-1+/IL2R+to differentiate, whereas r-IL-2 blocked normal differentiation and expansion of donor Thy-1-lo/Thym, but did not show any significant effect on donor Thy-1+/IL2R+. Neither r-IL-2 nor r-IL-6 worked directly on donor Thy-1-lo/BM in this transfer system.

scholarly journals Liposomes embedded with differentiating factors as a new strategy for enhancing DPSC osteogenic commitment

2021 ◽  
Vol 41 ◽  
pp. 108-120
Author(s):  
M Gallorini ◽  
◽  
R Di Carlo ◽  
S Pilato ◽  
A Ricci ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Stem Cell ◽  
Culture Media ◽  
Redox Balance ◽  
Phospholipid Bilayer ◽  
Matrix Deposition ◽  
New Strategy ◽  
Human Dental Pulp ◽  
Normal Differentiation ◽  
Cell Commitment

Human dental pulp stem cell (DPSC) differentiation toward the osteoblastic phenotype is enhanced when culture media are supplemented with differentiating factors, i.e. ascorbic acid, β-glycerophosphate and dexamethasone. Liposomes, spherical vesicles formed by a phospholipid bilayer, are frequently used as carriers for drugs, growth factors and hydrophobic molecules. The aim of this work was to speed up DPSC commitment to the osteogenic lineage by embedding differentiating factors within liposomes. Firstly, liposomes were prepared by rehydrating a phospholipidic thin film and characterised in terms of dimensions. Secondly, liposome-exposed DPSCs were characterised by their immunophenotypic profile. Levels of CD90 were significantly decreased in the presence of liposomes filled with ascorbic acid, β-glycerophosphate and dexamethasone (Lipo-Mix) with respect to normal differentiation medium (DM), while CD73 and CD29 expression were enhanced, suggesting osteogenic commitment. Additionally, an appreciable extracellular matrix deposition is detected. Thirdly, the Lipo-Mix formulation better increases alkaline phosphatase activity and levels of Collagen I secretion with respect to DM. In parallel, the new liposome formulation is capable of decreasing the release of H2O2 and of triggering a precocious antioxidant cell response, redressing the redox balance required upon mesenchymal stem cell commitment to osteogenesis. It can be therefore hypothesised that Lipo-Mix could represent a suitable tool for clinical regenerative purposes in the field of tissue engineering by speeding up DPSC osteogenic commitment, mineralised matrix deposition and remodelling.

Rôle du mésoderme somitique dans le développement du plumage dorsal chez l'embryon de Poulet

Development ◽  
1972 ◽  
Vol 28 (2) ◽  
pp. 343-366
Author(s):  
Par Annick Mauger
Keyword(s):  
Early Stage ◽  
Cervical Region ◽  
Lumbar Region ◽  
Chick Embryos ◽  
A Chain ◽  
Normal Differentiation ◽  
Time Of Operation ◽  
Somitic Mesoderm ◽  
Axial Organs

The role of somitic mesoderm in the development of dorsal plumage in chick embryos. II. Regionalisation. Transplantation and inversion experiments were performed on the somitic mesoderm of 2- to 2·5-day chick embryos in order to study the role of regional and axial determinations in the development of the dorsal plumage. The transposition of a piece of somitic mesoderm from the posterior cervical region (where the spinal pteryla is narrow) to the thoraco-lumbar region (where it is wide) leads to a local and unilateral narrowing of the spinal pteryla at the operation site. Conversely, the transposition of somitic mesoderm from the thoraco-lumbar region to the posterior cervical region results in a local and unilateral widening of the spinal pteryla. Consequently at the time of operation the segmented or not yet segmented somitic mesoderm is already determined to give rise to a definite transverse level of the spinal pteryla. The inversion of the cephalo-caudal polarity of a piece of somitic mesoderm without the ectodermal covering, or of a portion of the axial organs deprived of the overlying ectoderm has no effect on the orientation of feather filaments and feather rows. In contrast, the inversion of the cephalo-caudal polarity of a portion of the axial organs together with the overlying ectoderm results in the development of feathers growing in a cephalad direction and feather chevrons opening towards the head of the embryo. The inversion of the dorso-ventral polarity of a piece of somitic mesoderm does not prevent the normal differentiation of feathers in the operated region. The inversion of the medio-lateral polarity of a piece of unsegmented somitic mesoderm has little effect on the development of the spinal pteryla. On the contrary, the medio-lateral inversion of a chain of somites precludes the formation of the feathers at the level of operation. The somitic mesoderm, even when segmented, is endowed with extensive regulative capacity of its axes, except for the medio-lateral polarity, which is fixed irreversibly at the time of segmentation. The regional determination of the feather-forming somitic mesoderm is acquired at an early stage, at any rate before segmentation. However, at a given transverse level of the cephalo-caudal axis, the somitic cells remain totipotent as concerns their histo-genetic destiny (dermatome, myotome, or sclerotome) until after the onset of segmentation.

scholarly journals Oxidative Stress Impact on the Transcriptome of Differentiating Neuroblastoma Cells: Implication for Psychiatric Disorders

2020 ◽  
Vol 21 (23) ◽  
pp. 9182
Author(s):  
Behnaz Khavari ◽  
Ebrahim Mahmoudi ◽  
Michael P. Geaghan ◽  
Murray J. Cairns
Keyword(s):  
Oxidative Stress ◽  
Psychiatric Disorders ◽  
Neural Differentiation ◽  
System Development ◽  
Neuroblastoma Cells ◽  
Circulatory System ◽  
Early Life Exposure ◽  
Neuronal Gene ◽  
Normal Differentiation ◽  
Transcriptomic Changes

Prenatal environmental exposures that have been shown to induce oxidative stress (OS) during pregnancy, such as smoking and alcohol consumption, are risk factors for the onset of schizophrenia and other neurodevelopmental disorders (NDDs). While the OS role in the etiology of neurodegenerative diseases is well known, its contribution to the genomic dysregulation associated with psychiatric disorders is less well defined. In this study we used the SH-SY5Y cell line and applied RNA-sequencing to explore transcriptomic changes in response to OS before or during neural differentiation. We observed differential expression of many genes, most of which localised to the synapse and were involved in neuronal differentiation. These genes were enriched in schizophrenia-associated signalling pathways, including PI3K/Akt, axon guidance, and signalling by retinoic acid. Interestingly, circulatory system development was affected by both treatments, which is concordant with observations of increased prevalence of cardiovascular disease in patients with NDDs. We also observed a very significant increase in the expression of immunity-related genes, supporting current hypotheses of immune system involvement in psychiatric disorders. While further investigation of this influence in other cell and animal models is warranted, our data suggest that early life exposure to OS has a disruptive influence on neuronal gene expression that may perturb normal differentiation and neurodevelopment, thereby contributing towards overall risk for developing psychiatric diseases.

scholarly journals Comparative effects of testosterone propionate, oestradiol benzoate, ICI 182,780, tamoxifen and raloxifene on hypothalamic differentiation in the female rat

2002 ◽  
Vol 172 (3) ◽  
pp. 441-448 ◽  
Author(s):  
L Pinilla ◽  
ML Barreiro ◽  
LC Gonzalez ◽  
M Tena-Sempere ◽  
E Aguilar
Keyword(s):  
Positive Feedback ◽  
Testosterone Propionate ◽  
Reproductive Function ◽  
Female Rats ◽  
Normal Brain ◽  
Female Rat ◽  
Vaginal Opening ◽  
Ici 182,780 ◽  
Oestradiol Benzoate ◽  
Normal Differentiation

Hypothalamic differentiation in the female rat during the neonatal period is critically dependent on the steroid milieu, as permanent changes in reproductive function are observed after administration of oestradiol and testosterone during such a critical stage. Selective oestrogen modulators (SERMs) constitute a family of drugs that, depending on the tissue, are able to exert oestrogenic or antioestrogenic actions. The present experiments were conducted to analyse whether the SERMs, tamoxifen and raloxifene, can cause oestrogenic actions during the hypothalamic differentiation period. Postnatal female rats were injected between days 1 and 5 with 100 microg/day tamoxifen, raloxifene or ICI 182,780 (a pure antioestrogen). Other groups of animals were injected on day 1 of age with 100 microg oestradiol benzoate (OeB) or 1.25 mg testosterone propionate (TP) alone or in combination with raloxifene (500 microg/day between days 1 and 5). In all experimental groups, the age, body weight and concentrations of serum gonadotrophins at vaginal opening were recorded, whereas vaginal cyclicity and the negative and positive feedback between oestradiol and LH were monitored in adulthood. The results obtained confirmed the ability of high doses of OeB or TP to alter the normal differentiation of the brain permanently. They also reinforced the hypothesis that oestrogens are also necessary for normal brain differentiation in female rats because administration of a pure antioestrogen, such as ICI 182,780 permanently altered the function of the reproductive axis. In addition, our data provided evidence for different actions of the two SERMs under analysis (raloxifene and tamoxifen) upon peripheral targets, as raloxifene advanced vaginal opening whereas tamoxifen did not. In contrast, their actions on brain differentiation appeared similar and analogous to those obtained after neonatal administration of oestradiol, as evidenced by vaginal acyclicity, ovarian atrophy, sterility and abolition of negative and positive feedback between oestradiol and LH, thus suggesting an oestrogenic action of these SERMs on hypothalamic differentiation. Moreover, the oestrogenic activity of raloxifene was supported by its inability to block the effects of OeB and TP administered neonatally. In conclusion, the present results indicated that the SERMs, tamoxifen and raloxifene, exert an oestrogen-like effect upon hypothalamic differentiation of the neonatal female rat.

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