Incompetence of stem epidermal cells to dedifferentiate and graft

1985 ◽  
Vol 63 (12) ◽  
pp. 2129-2132 ◽  
Author(s):  
Dan B. Walker ◽  
David K. Bruck
Keyword(s):  
Wound Closure ◽  
Callus Tissue ◽  
Epidermal Cells ◽  
Epidermal Differentiation ◽  
Cortical Tissue ◽  
Graft Union ◽  
Cortical Cells ◽  
Cell Dedifferentiation ◽  
Tissue Removal ◽  
Tissue Responses

An intact mature epidermis precluded formation of approach grafts of stems of five angiospermous species. When the epidermis was excised, unsclerified cortical tissue exhibited tissue responses resulting in wound closure, including cell dedifferentiation and redifferentiation into callus tissue. Removal of the epidermis from both partners resulted in a graft union. Cortical callus tissue proliferated and coalesced to bind the partners. None of these responses associated with grafting or wound closure occurred in either epidermal or subepidermal tissue in intact partners. Whereas cortical cells adjacent to a cut region reacted in a similar way to those underlying the cut, neighboring epidermal cells were usually unaltered. This developmental quiescence of epidermal cells is a unique characteristic, useful in studies of epidermal differentiation and determination.

Cell determination during embryogenesis in Citrus jambhiri. III. Graft formation and nonformation in embryonic tissues

1986 ◽  
Vol 64 (9) ◽  
pp. 2057-2062 ◽  
Author(s):  
David K. Bruck ◽  
Dan B. Walker
Keyword(s):  
Callus Tissue ◽  
Graft Union ◽  
Citrus Jambhiri ◽  
Cell Determination ◽  
Longitudinal Incision ◽  
Embryonic Tissues ◽  
Globular Embryos ◽  
Tissue Removal

Approach grafts were constructed using embryos in vitro with and without surface tissue removal along the root–hypocotyl axis. All embryonic stages from mid-heart through mature proved competent to graft after surface excision. Early heart-shaped embryos grafted back to themselves when a longitudinal incision was made which cut the hypocotyl in half but left the root intact. Cut globular embryos could not be maintained in position for a sufficient period to generate a graft union. Callus tissue was produced in all cut embryos by internal cells but not by surface cells neighboring the cut region. Intact embryos failed to graft or respond in any fashion. The incompetence to graft of surface tissues at all embryonic stages indicates that those tissues are determined as epidermal even in the earliest stages of embryogenesis. Internal cells of the embryo were not epidermal in response. They were able to form callus and graft with increasing ease toward older stages of embryogenesis.

A Deficiency Screen for Zygotic Loci Required for Establishment and Patterning of the Epidermis in Caenorhabditis elegans

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 185-206 ◽  
Author(s):  
Rebecca M Terns ◽  
Peggy Kroll-Conner ◽  
Jiangwen Zhu ◽  
Sooyoun Chung ◽  
Joel H Rothman
Keyword(s):  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Epidermal Cells ◽  
Epidermal Differentiation ◽  
Apparent Effect ◽  
Internal Organs ◽  
C Elegans ◽  
Seam Cell ◽  
Genomic Regions ◽  
Caenorhabditis Elegans Genome

To identify genomic regions required for establishment and patterning of the epidermis, we screened 58 deficiencies that collectively delete at least ∼67% of the Caenorhabditis elegans genome. The epidermal pattern of deficiency homozygous embryos was analyzed by examining expression of a marker specific for one of the three major epidermal cell types, the seam cells. The organization of the epidermis and internal organs was also analyzed using a monoclonal antibody specific for epithelial adherens junctions. While seven deficiencies had no apparent effect on seam cell production, 21 were found to result in subnormal, and five in excess numbers of these cells. An additional 23 deficiencies blocked expression of the seam cell marker, in some cases without preventing cell proliferation. Two deficiencies result in multinucleate seam cells. Deficiencies were also identified that result in subnormal numbers of epidermal cells, hyperfusion of epidermal cells into a large syncytium, or aberrant epidermal differentiation. Finally, analysis of internal epithelia revealed deficiencies that cause defects in formation of internal organs, including circularization of the intestine and bifurcation of the pharynx lumen. This study reveals that many regions of the C. elegans genome are required zygotically for patterning of the epidermis and other epithelia.

Refining the Life Cycle of Plasmodiophora brassicae

2020 ◽  
Vol 110 (10) ◽  
pp. 1704-1712 ◽  
Author(s):  
Lijiang Liu ◽  
Li Qin ◽  
Zhuqing Zhou ◽  
Wilhelmina G. H. M. Hendriks ◽  
Shengyi Liu ◽  
...  
Keyword(s):  
Life Cycle ◽  
Plasmodiophora Brassicae ◽  
Secondary Infection ◽  
Life Stage ◽  
Infection Process ◽  
Epidermal Cells ◽  
Sexual Life ◽  
Cortical Cells ◽  
Susceptible Host ◽  
Clubroot Disease

As a soilborne protist pathogen, Plasmodiophora brassicae causes the devastating clubroot disease on Brassicaceae crops worldwide. Due to its intracellular obligate biotrophic nature, the life cycle of P. brassicae is still not fully understood. Here, we used fluorescent probe-based confocal microscopy and transmission electron microscopy (TEM) to investigate the infection process of P. brassicae on the susceptible host Arabidopsis under controlled conditions. We found that P. brassicae can initiate the primary infection in both root hairs and epidermal cells, producing the uninucleate primary plasmodium at 1 day postinoculation (dpi). After that, the developed multinucleate primary plasmodium underwent condensing and cytoplasm cleavage into uninucleate zoosporangia from 1 to 4 dpi. This was subsequently followed by the formation of multinucleate zoosporangia and the production of secondary zoospores within zoosporangium. Importantly, the secondary zoospores performed a conjugation in the root epidermal cells after their release. TEM revealed extensive uninucleate secondary plasmodium in cortical cells at 8 dpi, indicating the establishment of the secondary infection. The P. brassicae subsequently developed into binucleate, quadrinucleate, and multinucleate secondary plasmodia from 10 to 15 dpi, during which the clubroot symptoms appeared. The uninucleate resting spores were first observed in the cortical cells at 24 dpi, marking the completion of a life cycle. We also provided evidence that the secondary infection of P. brassicae may represent the diploid sexual life stage. From these findings, we propose a refined life cycle of P. brassicae which will contribute to understanding of the complicated infection biology of P. brassicae.

scholarly journals Seed-transmitted beneficial endophytic Stagonospora sp. can penetrate the walls of the root epidermis, but does not proliferate in the cortex, of Phragmites australis

2006 ◽  
Vol 84 (6) ◽  
pp. 981-988 ◽  
Author(s):  
Kexiang Gao ◽  
Kurt Mendgen
Keyword(s):  
Phragmites Australis ◽  
Endophytic Fungus ◽  
Hyphal Growth ◽  
Root Surface ◽  
Cortical Layer ◽  
Epidermal Cells ◽  
Cortical Cells ◽  
Root Epidermis ◽  
Wall Appositions

Stagonospora sp. (4/99-1) is a beneficial endophytic fungus frequently transmitted by seeds of Phragmites australis [Cav.] Trin. ex Steudel. Here we show that this fungus also penetrates the root epidermis. At first, hyphae were attracted by the root and proliferated on the root surface, preferably over the anticlinal walls. Penetration occurred directly by undifferentiated hyphae or was facilitated by hyphopodia. Hyphal growth within the root was restricted to the walls of epidermal cells and the walls of the cells of the outermost cortical layer. Deeper growth by the fungus elicited wall appositions and ingress into the cytoplasm of cortical cells was blocked by papillae. In the rare cases, the fungus managed to penetrate into cortical cells, these reacted with necrosis. Immunological studies suggested that fungal material reached the host plasmalemma and may have been taken up by endocytotic events. Our observations explain the endophytic lifestyle of hyphae close to the epidermis and the restricted development within the cortex.

scholarly journals Modification of cell surface glycoprotein: addition of fucosyl residues during epidermal differentiation.

1982 ◽  
Vol 95 (2) ◽  
pp. 626-631 ◽  
Author(s):  
J D Zieske ◽  
I A Bernstein
Keyword(s):  
Cell Surface ◽  
Lectin Binding ◽  
Epidermal Cells ◽  
Epidermal Differentiation ◽  
Surface Glycoprotein ◽  
Basal Cells ◽  
Cell Surface Glycoprotein ◽  
Similar Treatment ◽  
Differentiated Cells ◽  
Cell Layers

When cutaneous sections from the newborn rat were treated with alpha-fucosidase, Ulex europeus agglutinin I (UEA) binding to the cell surface of the differentiated cells in the epidermis was diminished and there was an appearance in these cell layers of binding by Bandeiraea simplicifolia I-B4 lectin (BS I-B4), which normally is specific for the basal cells. A similar treatment with alpha-galactosidase resulted in a loss of BS I-B4 binding, but had no effect on UEA binding. Glycoproteins isolated from the membranes of epidermal cells showed a threefold increase in the ratio of binding to UEA versus BS I-B4 affinity columns as the proteins were derived from the more differentiated cell populations. These data suggest that alpha-fucosyl residues are added to the glycoproteins on the cell surfaces of differentiated cells, thus blocking alpha-galactosyl residues and changing the lectin binding specificity as epidermal cells move out of the basal cell layer.

scholarly journals Profilaggrin is a major epidermal calcium-binding protein.

1993 ◽  
Vol 13 (1) ◽  
pp. 613-625 ◽  
Author(s):  
N G Markova ◽  
L N Marekov ◽  
C C Chipev ◽  
S Q Gan ◽  
W W Idler ◽  
...  
Keyword(s):  
Calcium Binding ◽  
Expression Patterns ◽  
Epidermal Cells ◽  
Epidermal Differentiation ◽  
Amino Terminus ◽  
Calcium Signal ◽  
Dependent Manner ◽  
Structural Protein ◽  
Rnase Protection

Profilaggrin is a major highly phosphorylated protein component of the keratohyalin granules of mammalian epidermis. It contains 10 to 12 tandemly repeated filaggrin units and is processed into the intermediate filament-associated protein filaggrin by specific dephosphorylation and proteolysis during terminal differentiation of the epidermal cells. Later, filaggrin itself is degraded to free amino acids that participate in maintenance of epidermal flexibility. The present paper describes the structural organization of the 5' region of the human profilaggrin gene as well as the amino terminus of the profilaggrin protein. The primary profilaggrin transcript consists of three exons and two introns. The first exon (exon I) is only 54 bp and is untranslated. The coding sequences are distributed between exon II (159 bp) and exon III, which contains the information for 10 to 12 filaggrin repeats (972 bp each) and the 3' noncoding sequences. A very large intron separates exons I and II. The combination of a very short exon I with an unusually long intron 1 makes the structure of the profilaggrin gene unique among the epidermally expressed genes investigated so far. Comparison of the expression patterns revealed by primer extension and RNase protection analysis of foreskin epidermal and cultured keratinocyte RNAs suggests that alternately spliced messages, which are different from profilaggrin mRNA, are transcribed from the profilaggrin gene system at earlier stages of epidermal differentiation. The amino terminus of profilaggrin exhibits a significant homology to the small calcium-binding S100-like proteins. It contains two alpha-helical regions, termed EF-hands, that bind calcium in vitro. This is the first example of functional calcium-binding domains fused to a structural protein. We suggest that in addition to its role in filament aggregation and the maintenance of epidermal flexibility, profilaggrin may play an important role in the differentiation of the epidermis by autoregulating its own processing in a calcium-dependent manner or by participating in the transduction of calcium signal in epidermal cells.

scholarly journals The Class II Phosphoinositide 3-Kinase C2β Is Not Essential for Epidermal Differentiation

2005 ◽  
Vol 25 (24) ◽  
pp. 11122-11130 ◽  
Author(s):  
Kazutoshi Harada ◽  
Amy B. Truong ◽  
Ti Cai ◽  
Paul A. Khavari
Keyword(s):  
Class Ii ◽  
Epidermal Cells ◽  
Epidermal Differentiation ◽  
Class I ◽  
Differentiation Markers ◽  
Cellular Processes ◽  
Targeted Gene Deletion ◽  
Epidermal Growth ◽  
Phosphoinositide 3 Kinase

ABSTRACT Phosphoinositide 3-kinases (PI3Ks) regulate an array of cellular processes and are comprised of three classes. Class I PI3Ks include the well-studied agonist-sensitive p110 isoforms; however, the functions of class II and III PI3Ks are less well characterized. Of the three class II PI3Ks, C2α and C2β are widely expressed in many tissues, including the epidermis, while C2γ is confined to the liver. In contrast to the class I PI3K p110α, which is expressed throughout the epidermis, C2β was found to be localized in suprabasal cells, suggesting a potential role for C2β in epidermal differentiation. Overexpressing C2β in epidermal cells in vitro induced differentiation markers. To study a role for C2β in tissue, we generated transgenic mice overexpressing C2β in both suprabasal and basal epidermal layers. These mice lacked epidermal abnormalities. Mice deficient in C2β were then generated by targeted gene deletion. C2β knockout mice were viable and fertile and displayed normal epidermal growth, differentiation, barrier function, and wound healing. To exclude compensation by C2α, RNA interference was then used to knock down both C2α and C2β in epidermal cells simultaneously. Induction of differentiation markers was unaffected in the absence of C2α and C2β. These findings indicate that class II PI3Ks are not essential for epidermal differentiation.

scholarly journals Newt epidermal cell migration in vitro and in vivo appears to involve Arg-Gly-Asp-Ser receptors

1987 ◽  
Vol 87 (4) ◽  
pp. 525-534
Author(s):  
D.J. Donaldson ◽  
J.T. Mahan ◽  
G.N. Smith
Keyword(s):  
Receptor Binding ◽  
Binding Sites ◽  
Wound Closure ◽  
Type I Collagen ◽  
Attachment Site ◽  
Epidermal Cells ◽  
Type I ◽  
Human Fibrinogen ◽  
Skin Explants

The effect of a synthetic peptide consisting of Arg-Gly-Asp-Ser (RGDS), the amino acid sequence representing the fibroblast attachment site in fibronectin (FN), was tested on migrating newt epidermal cells. In one approach, skin explants were placed on the bottom of plastic dishes coated with human FN, human fibrinogen (FGN), human serum spreading factor (SF), or bovine type I collagen. The explants were then incubated overnight in serum-free medium with or without RGDS. In these experiments exposure to 50 micrograms ml-1 of RGDS reduced migration over FN, FGN and SF to 2–7% of control levels. Two peptides structurally dissimilar to RGDS (Val-Gly-Ser-Glu and Thr-Pro-Arg-Lys), and two that are structurally similar (Lys-Gly-Asp-Ser and Arg-Gly-Glu-Ser), had no effect on explant migration even when used at concentrations higher than 50 micrograms ml-1. Upon removal of the RGDS peptide, inhibited explants quickly recovered. In collagen-coated dishes 50 micrograms ml-1 of RGDS was much less effective than in dishes coated with the other substrates. Raising the RGDS concentration in collagen-coated dishes tenfold did not greatly increase the RGDS effect. When added to the medium bathing wounded limbs, 50 micrograms ml-1 of RGDS only moderately inhibited wound closure. This concentration of peptide, however, severely inhibited migration from skin explants in newt-plasma-coated-dishes and migration over pieces of newt-plasma-coated plastic placed under one edge of a skin wound. Increasing the RGDS concentration to 500 micrograms ml-1 resulted in almost total suppression of wound closure. Wounds exposed to this same concentration of Lys-Gly-Asp-Ser closed normally. These results indicate that newt epidermal cells possess RGDS receptors and that these receptors are involved in epidermal wound closure in vivo and in migration from skin explants onto plastic coated with FN, FGN, SF and collagen. The relative RGDS-insensitivity of wound closure in vivo and in migration from explants onto collagen may reflect in these instances the presence of a relatively high density of RGDS receptor binding sites on the substrate; the presence of RGDS receptor binding sites of relatively high affinity; or the participation of receptors other than those involved in migration over plastic coated with FN, FGN or SF.

scholarly journals Ultrastructure of the Penetration and Infection of Pansy Roots by Thielaviopsis basicola

2000 ◽  
Vol 90 (8) ◽  
pp. 843-850 ◽  
Author(s):  
Charles W. Mims ◽  
Warren E. Copes ◽  
Elizabeth A. Richardson
Keyword(s):  
Filter Paper ◽  
Germ Tube ◽  
Epidermal Cells ◽  
Host Cells ◽  
Thielaviopsis Basicola ◽  
Cortical Cells ◽  
Infection Structures ◽  
Transmission Electron ◽  
Papilla Formation ◽  
Potting Media

Transmission electron microscopy was used to study the penetration and infection of pansy roots by Thielaviopsis basicola. Events observed in 7- to 10-day-old roots produced on moist filter paper differed slightly from those in roots from 4-week-old plants washed free of potting media prior to inoculation. By 3 h postinoculation (PI), epidermal cells of roots produced on filter paper exhibited aggregated cytoplasm and papilla formation in response to germ tube tips. The presence of callose in papillae was demonstrated using immunogold labeling. Papilla formation was not effective in preventing host cell penetration. A slender infection hypha emerged from a germ tube tip and grew through a papilla. Its tip then expanded to form a globose infection vesicle. By 6 h PI, infection hyphae emerged from infection vesicles, and invaded host cells showed signs of necrosis. By 8 h PI, infection hyphae had grown into cortical cells in spite of papilla formation in these cells. By 24 h PI, distinctive intracellular hyphae were present in necrotic cortical cells. In washed roots, most epidermal cells failed to respond to invasion. Hyphae simply grew through these cells and contacted cortical cells that exhibited aggregated cytoplasm and papillae formation. Infection structures similar to those produced in epidermal cells from roots grown on filter paper then formed in cortical cells of washed roots. The fact that T. basicola formed infection structures only in cells that responded to invasion suggests that T. basicola has a more complex relationship with its host than would be expected in a nectrotrophic pathogen. We believe that T. basicola is best described as a necrotrophic hemibiotroph.

scholarly journals 31P Relaxation Responses Associated with N2/O2 Diffusion in Soybean Nodule Cortical Cells and Excised Cortical Tissue

1992 ◽  
Vol 100 (4) ◽  
pp. 1682-1690 ◽  
Author(s):  
Philip E. Pfeffer ◽  
Dominique B. Rolin ◽  
Thomas F. Kumosinski ◽  
Janet S. MacFall ◽  
Julian H. Schmidt
Keyword(s):  
Cortical Tissue ◽  
Cortical Cells ◽  
Soybean Nodule ◽  
31P Relaxation ◽  
O2 Diffusion ◽  
Relaxation Responses
Sign in / Sign up

Export Citation Format

Share Document