scholarly journals Studies of Schwann cell proliferation. II. Characterization of the stimulation and specificity of the response to a neurite membrane fraction.

1980 ◽  
Vol 84 (3) ◽  
pp. 753-766 ◽  
Author(s):  
J L Salzer ◽  
A K Williams ◽  
L Glaser ◽  
R P Bunge
Keyword(s):  
Schwann Cells ◽  
Membrane Fraction ◽  
Tritiated Thymidine ◽  
Cell Types ◽  
Primary Cells ◽  
Sensory Ganglion ◽  
Cell Layers ◽  
Multiple Cell ◽  
Peripheral Sensory

When prepared by methods utilized in our laboratory, pure populations of Schwann cells in culture do not divide, but, after recombination with peripheral sensory neurons or their processes, proliferate rapidly (Wood and Bunge, 1975, Nature (Lond.) 256:661--664). In this paper, we demonstrate that a membrane fraction prepared from sensory ganglion neurites is also mitogenic for Schwann cells and increases the labeling index (assessed by autoradiography after incubation of cells with tritiated thymidine) from less than 0.2 to 10% for primary cells, and from 0.4 to 18--19% for replated cells. The increased responsiveness of replated cells may reflect their greater access to the neurite membranes which is a consequence of the elimination of multiple cell layers after replating and the removal of the basal lamina. This stimulation was specific; addition of membrane preparations from other cell types (3T3, C1300, etc.) was not mitogenic. Ultrastructural analysis demonstrated apparent binding of neurite membranes to Schwann cells as well as significant phagocytosis of the membranes by the cells. The uptake of nonmitogenic membranes suggests that phagocytosis per se is not the stimulus of proliferation.

scholarly journals Exo-enzymatic addition of diazirine-modified sialic acid to cell surfaces enables photocrosslinking of glycoproteins

2021 ◽  
Author(s):  
Nageswari Yarravarapu ◽  
Rohit Sai Reddy Konada ◽  
Narek Darabedian ◽  
Nichole J. Pedowtiz ◽  
Soumya N. Krishnamurthy ◽  
...  
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Cell Types ◽  
Cell Surfaces ◽  
Binding Interactions ◽  
Multiple Cell ◽  
Labeling Method ◽  
Cell Surface Glycoconjugates

Glycan binding often mediates extracellular macromolecular recognition events. Accurate characterization of these binding interactions can be difficult because of dissociation and scrambling that occur during purification and analysis steps. Use of photocrosslinking methods has been pursued to covalently capture glycan-dependent interactions in situ however use of metabolic glycan engineering methods to incorporate photocrosslinking sugar analogs is limited to certain cell types. Here we report an exo-enzymatic labeling method to add a diazirine-modified sialic acid (SiaDAz) to cell surface glycoconjugates. The method involves chemoenzymatic synthesis of diazirine-modified CMP-sialic acid (CMP-SiaDAz), followed by sialyltransferase-catalyzed addition of SiaDAz to desialylated cell surfaces. Cell surface SiaDAz-ylation is compatible with multiple cell types and is facilitated by endogenous extracellular sialyltransferase activity present in Daudi B cells. This method for extracellular addition of α2-6-linked SiaDAz enables UV-induced crosslinking of CD22, demonstrating the utility for covalent capture of glycan-mediated binding interactions.

scholarly journals Platform technology for scalable assembly of instantaneously functional mosaic tissues

2015 ◽  
Vol 1 (7) ◽  
pp. e1500423 ◽  
Author(s):  
Boyang Zhang ◽  
Miles Montgomery ◽  
Locke Davenport-Huyer ◽  
Anastasia Korolj ◽  
Milica Radisic
Keyword(s):  
Three Dimensional ◽  
Electrical Field Stimulation ◽  
Cell Types ◽  
Matrix Remodeling ◽  
Cell Alignment ◽  
Cell Coating ◽  
Cell Layers ◽  
Invasive Method ◽  
Multiple Cell ◽  
Mechanical Cutting

Engineering mature tissues requires a guided assembly of cells into organized three-dimensional (3D) structures with multiple cell types. Guidance is usually achieved by microtopographical scaffold cues or by cell-gel compaction. The assembly of individual units into functional 3D tissues is often time-consuming, relying on cell ingrowth and matrix remodeling, whereas disassembly requires an invasive method that includes either matrix dissolution or mechanical cutting. We invented Tissue-Velcro, a bio-scaffold with a microfabricated hook and loop system. The assembly of Tissue-Velcro preserved the guided cell alignment realized by the topographical features in the 2D scaffold mesh and allowed for the instant establishment of coculture conditions by spatially defined stacking of cardiac cell layers or through endothelial cell coating. The assembled cardiac 3D tissue constructs were immediately functional as measured by their ability to contract in response to electrical field stimulation. Facile, on-demand tissue disassembly was demonstrated while preserving the structure, physical integrity, and beating function of individual layers.

scholarly journals The Hematopoietic Niche in Myeloproliferative Neoplasms

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Annette H. Schmitt-Graeff ◽  
Roland Nitschke ◽  
Robert Zeiser
Keyword(s):  
Myeloproliferative Neoplasms ◽  
Treatment Strategies ◽  
Cell Types ◽  
Additional Treatment ◽  
Molecular Networks ◽  
Hematopoietic Stem ◽  
Endosteal Niche ◽  
Hsc Niche ◽  
Multiple Cell

Specialized microanatomical areas of the bone marrow provide the signals that are mandatory for the maintenance and regulation of hematopoietic stem cells (HSCs) and progenitor cells. A complex microenvironment adjacent to the marrow vasculature (vascular niche) and close to the endosteum (endosteal niche) harbors multiple cell types including mesenchymal stromal cells and their derivatives such as CAR cells expressing high levels of chemokines C-X-C motif ligand 12 and early osteoblastic lineage cells, endothelial cells, and megakaryocytes. The characterization of the cellular and molecular networks operating in the HSC niche has opened new perspectives for the understanding of the bidirectional cross-talk between HSCs and stromal cell populations in normal and malignant conditions. A structural and functional remodeling of the niche may contribute to the development of myeloproliferative neoplasms (MPN). Malignant HSCs may alter the function and survival of MSCs that do not belong to the neoplastic clone. For example, a regression of nestin+MSCs by apoptosis has been attributed to neuroglial damage in MPN. Nonneoplastic MSCs in turn can promote aggressiveness and drug resistance of malignant cells. In the future, strategies to counteract the pathological interaction between the niche and neoplastic HSCs may offer additional treatment strategies for MPN patients.

scholarly journals Ultrastructure of Feline Mammary Hypertrophy

1983 ◽  
Vol 20 (3) ◽  
pp. 254-264 ◽  
Author(s):  
D. W. Hayden ◽  
K. H. Johnson ◽  
H. K. Ghobrial
Keyword(s):  
Basal Lamina ◽  
Plasma Membranes ◽  
Secretory Activity ◽  
Cell Types ◽  
Myoepithelial Cells ◽  
Mammary Tissue ◽  
Stromal Fibroblasts ◽  
Cell Layers ◽  
Multiple Cell ◽  
One Year

The ultrastructure of feline mammary hypertrophy was studied in a five-month-old female which had aborted recently, a ten-year-old female which was one month postestrus, and a four-year-old progestin-treated neutered male. Morphologic comparisons were made to normal mammary tissue from a one-year-old female cat. Hypertrophied mammary tissue had the same cell types and spatial relationships as did the normal gland. Major differences included a more highly developed duct system composed of metabolically active cells which often were arranged in multiple cell layers, and periductular stroma with increased fibroblasts and vascularization. Hypertrophied epithelial cells were characterized generally by smooth-contoured nuclear membranes, more evenly dispersed heterochromatin, prominent nucleoli, increased polyribosomes, and elongated mitochondria. Secretory activity was developed significantly only in the cat that had aborted recently. Modifications in myoepithelial cells included: more evenly dispersed nuclear heterochromatin, thicker bundles of cytoplasmic filaments, more straight plasma membranes along the basal lamina, and elongated hemidesmosomes. Multilayering of the basal lamina was accentuated. Stromal fibroblasts had nuclear heterochromatin distributed similarly to that of epithelial and myoepithelial cells, and increased rough endoplasmic reticulum. Myoepithelial cells did not contribute to the increased stromal cellularity. No significant ultrastructural differences were noted between mammary hypertrophy in young, old, and progestin-treated cats.

scholarly journals Hidden cell diversity in Placozoa: Ultrastructural Insights from Hoilungia hongkongensis

2020 ◽  
Author(s):  
Daria Y. Romanova ◽  
Frederique Varoqueaux ◽  
Jean Daraspe ◽  
Mikhail A. Nikitin ◽  
Michael Eitel ◽  
...  
Keyword(s):  
Cell Types ◽  
Lower Surface ◽  
Point Of View ◽  
Cell Type ◽  
Free Living ◽  
Trichoplax Adhaerens ◽  
Genetic Complexity ◽  
Cell Diversity ◽  
Cell Layers

AbstractFrom a morphological point of view, placozoans are among the most simple free-living animals. This enigmatic phylum is critical for our understanding of the evolution of animals and their cell types. Their millimeter-sized, disc-like bodies consist of only three cell layers that are shaped by roughly six major cell types. Placozoans lack muscle cells and neurons but are able to move using their ciliated lower surface and take up food in a highly coordinated manner. Intriguingly, the genome of Trichoplax adhaerens, the founding member of the enigmatic phylum, has disclosed a surprising level of genetic complexity. Moreover, recent molecular and functional investigations have uncovered a much larger, so-far hidden cell-type diversity. Here, we have extended the microanatomical characterization of a recently described placozoan species – Hoilungia hongkongensis. In H. hongkongensis, we recognized the established canonical three-layered placozoan body plan but also came across several morphologically distinct and potentially novel cell types, among them novel gland cells and “shiny spheres”-bearing cells at the upper epithelium. Thus, the diversity of cell types in placozoans is indeed higher than anticipated.

scholarly journals The Transcriptional Status but Not the Imprinting Control Region Determines Allele-Specific Histone Modifications at the Imprinted H19 Locus

2007 ◽  
Vol 28 (1) ◽  
pp. 71-82 ◽  
Author(s):  
Raluca I. Verona ◽  
Joanne L. Thorvaldsen ◽  
Kimberly J. Reese ◽  
Marisa S. Bartolomei
Keyword(s):  
Genomic Imprinting ◽  
Histone Modifications ◽  
Cell Types ◽  
Specific Gene ◽  
Histone Marks ◽  
Exon 1 ◽  
Allele Specific ◽  
Multiple Cell ◽  
Imprinting Control Region

ABSTRACT Genomic imprinting governs allele-specific gene expression in an epigenetically heritable manner. The characterization of histone modifications at imprinted gene loci is incomplete, and whether specific histone marks determine transcription or are dependent on it is not understood. Using chromatin immunoprecipitations, we examined in multiple cell types and in an allele-specific manner the active and repressive histone marks of several imprinted loci, including H19, KvDMR1, Snrpn promoter/exon 1, and IG-DMR imprinting control regions. Expressed alleles are enriched for specific actively modified histones, including H3 di- and trimethylated at Lys4 and acetylated histones H3 and H4, while their silent counterparts are associated with repressive marks such as H3 trimethylated at Lys9 alone or in combination with H3 trimethylated at Lys27 and H4/H2A symmetrically dimethylated at Arg3. At H19, allele-specific histone modifications occur throughout the entire locus, including nontranscribed regions such as the differentially methylated domain (DMD) as well as sequences in the H19 gene body that are not differentially methylated. Significantly, the presence of active marks at H19 depends on transcriptional activity and occurs even in the absence of the DMD. These findings suggest that histone modifications are dependent on the transcriptional status of imprinted alleles and illuminate epigenetic mechanisms of genomic imprinting.

scholarly journals Identification and characterization of cellular heterogeneity within the developing renal interstitium

Development ◽  
2020 ◽  
Vol 147 (15) ◽  
pp. dev190108 ◽  
Author(s):  
Alicia R. England ◽  
Christopher P. Chaney ◽  
Amrita Das ◽  
Mohita Patel ◽  
Alicia Malewska ◽  
...  
Keyword(s):  
Kidney Development ◽  
Cell Types ◽  
Developmental Trajectory ◽  
Cellular Heterogeneity ◽  
Renal Interstitium ◽  
Collecting Ducts ◽  
A Cell ◽  
Multiple Cell ◽  
Identification And Characterization

ABSTRACTKidney formation requires the coordinated growth of multiple cell types including the collecting ducts, nephrons, vasculature and interstitium. There is a long-held belief that interactions between progenitors of the collecting ducts and nephrons are primarily responsible for kidney development. However, over the last several years, it has become increasingly clear that multiple aspects of kidney development require signaling from the interstitium. How the interstitium orchestrates these various roles is poorly understood. Here, we show that during development the interstitium is a highly heterogeneous patterned population of cells that occupies distinct positions correlated to the adjacent parenchyma. Our analysis indicates that the heterogeneity is not a mere reflection of different stages in a linear developmental trajectory but instead represents several novel differentiated cell states. Further, we find that β-catenin has a cell autonomous role in the development of a medullary subset of the interstitium and that this non-autonomously affects the development of the adjacent epithelia. These findings suggest the intriguing possibility that the different interstitial subtypes may create microenvironments that play unique roles in development of the adjacent epithelia and endothelia.

γ-Aminobutyric acid immunoreactivity in multiple cell types of the developing rabbit retina

1992 ◽  
Vol 8 (3) ◽  
pp. 201-211 ◽  
Author(s):  
Elizabeth K. Messersmith ◽  
Dianna A. Redburn
Keyword(s):  
Cell Shape ◽  
Plexiform Layer ◽  
Cell Types ◽  
Rabbit Retina ◽  
Cell Type ◽  
General Hypothesis ◽  
Endogenous Gaba ◽  
Cell Layers ◽  
Multiple Cell ◽  
Plexiform Layers

AbstractWe have previously demonstrated that the neonatal rabbit retina contains a larger complement of cells that accumulate [3H]-GABA than does the adult. In order for these neurons to be classified as GABAergic, they must also contain endogenous GABA. We now report that these same neonatal cell populations are also immunoreactive to GABA antisera. In frozen sections from rabbit retina, treated with GABA antisera, immunoreactive processes in both synaptic layers were observed at postnatal day 1. The appearance of immunofluorescent fibers precedes that of photoreceptor and bipolar cell terminals in the outer plexiform layer and is diminished by postnatal day 5. Also noted, was a 50% decrease in the density of GABA-immunoreactive cell bodies in the inner nuclear and ganglion cell layers, accompanied by an increase in cell volume and a shift toward a more spherical cell shape of the remaining cells. At postnatal day 1 and 3, we also observed immunoreactive cells having the characteristic morphology of interplexiform cells. This cell type sends branches to both the outer and inner plexiform layers, thus a morphological basis for communication between the two developing plexiform layers is present as early as postnatal day 1. Thus, retinas from neonatal rabbits have a larger complement of cells that stain for endogenous GABA than does the adult. These results coupled with our previous studies suggest that GABAergic properties are expressed by a larger number of cell types in the neonate than in the adult and are consistent with the general hypothesis that GABA functions as a trophic agent during development.

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