Fine structure of the kinetochores in six species of the Coleoptera

Genome ◽  
1997 ◽  
Vol 40 (3) ◽  
pp. 379-385
Author(s):  
Klaus Werner Wolf
Keyword(s):  
Direct Contact ◽  
Karyotype Evolution ◽  
Coccinella Septempunctata ◽  
Cell Types ◽  
Male Meiosis ◽  
Serial Sections ◽  
Cell Type ◽  
Present Survey ◽  
Transmission Electron ◽  
Size Variability

Kinetochore structure was examined in a total of 6 species from 5 different families of the Coleoptera using transmission electron microscopy of ultrathin serial sections. Metaphase spermatogonia and primary and secondary spermatocytes were studied in Tenebrio molitor (Tenebrionidae) to determine whether kinetochore structure varies depending on the cell type. In all three cell types, the kinetochore microtubules (MTs) were in direct contact with the chromosomal surface, and kinetochore plates were not detectable. In the other species, only metaphase I spermatocytes were examined. As in T. molitor, distinct kinetochore plates were also absent in Adelocera murina (Elateridae), Agapanthia villosoviridescens (Cerambycidae), and Coccinella septempunctata (Coccinellidae). However, bivalents in male meiosis of two representatives of the Chrysomelidae, Agelastica alni and Chrysolina graminis, showed roughly spherical kinetochores at their poleward surfaces. Microtubules were in contact with this material. Thus, although the present survey covers only a small number of species, it is clear that at least two kinetochore types occur in the Coleoptera. The cytological findings are discussed in the context of chromosome number and genome size variability in the Coleopteran families studied. It is suggested that properties of the kinetochores could play a role in karyotype evolution in the Coleoptera.Key words: bivalent, microtubule, meiosis, metaphase, spermatocyte.

scholarly journals A multi-layered and dynamic apical extracellular matrix shapes the vulva lumen in Caenorhabditis elegans

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jennifer D Cohen ◽  
Alessandro P Sparacio ◽  
Alexandra C Belfi ◽  
Rachel Forman-Rubinsky ◽  
David H Hall ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Caenorhabditis Elegans ◽  
Cell Types ◽  
Extracellular Matrices ◽  
Cell Type ◽  
Transmission Electron ◽  
Genetic Perturbations ◽  
Lipid Transporters ◽  
Matrix Factors

Biological tubes must develop and maintain their proper diameter to transport materials efficiently. These tubes are molded and protected in part by apical extracellular matrices (aECMs) that line their lumens. Despite their importance, aECMs are difficult to image in vivo and therefore poorly understood. The Caenorhabditis elegans vulva has been a paradigm for understanding many aspects of organogenesis. Here we describe the vulva luminal matrix, which contains chondroitin proteoglycans, Zona Pellucida (ZP) domain proteins, and other glycoproteins and lipid transporters related to those in mammals. Confocal and transmission electron microscopy revealed, with unprecedented detail, a complex and dynamic aECM. Different matrix factors assemble on the apical surfaces of each vulva cell type, with clear distinctions seen between Ras-dependent (1°) and Notch-dependent (2°) cell types. Genetic perturbations suggest that chondroitin and other aECM factors together generate a structured scaffold that both expands and constricts lumen shape.

scholarly journals A multi-layered and dynamic apical extracellular matrix shapes the vulva lumen in Caenorhabditis elegans

2020 ◽  
Author(s):  
Jennifer D. Cohen ◽  
Alessandro P. Sparacio ◽  
Alexandra C. Belfi ◽  
Rachel Forman-Rubinsky ◽  
David H. Hall ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Types ◽  
Extracellular Matrices ◽  
Cell Type ◽  
C Elegans ◽  
Transmission Electron ◽  
Genetic Perturbations ◽  
Lipid Transporters ◽  
Matrix Factors

AbstractBiological tubes must develop and maintain their proper diameter in order to transport materials efficiently. These tubes are molded and protected in part by apical extracellular matrices (aECMs) that line their lumens. Despite their importance, aECMs are difficult to image in vivo and therefore poorly understood. The C. elegans vulva has been a paradigm for understanding many aspects of organogenesis. Here we describe the vulva luminal matrix, which contains chondroitin proteoglycans, Zona Pellucida (ZP) domain proteins, and other glycoproteins and lipid transporters related to those in mammals. Confocal and transmission electron microscopy revealed, with unprecedented detail, a complex and dynamic aECM. Different matrix factors assemble on the apical surfaces of each vulva cell type, with clear distinctions seen between Ras-dependent (1°) and Notch-dependent (2°) cell types. Genetic perturbations suggest that chondroitin and other aECM factors together generate a structured scaffold that both expands and constricts lumen shape.

scholarly journals Expression of neural cell adhesion molecule (N-CAM) in rat islets and its role in islet cell type segregation

1994 ◽  
Vol 107 (6) ◽  
pp. 1429-1436 ◽  
Author(s):  
V. Cirulli ◽  
D. Baetens ◽  
U. Rutishauser ◽  
P.A. Halban ◽  
L. Orci ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
B Cells ◽  
Pancreatic Polypeptide ◽  
Islet Cells ◽  
Cell Types ◽  
Serial Sections ◽  
Cell Type ◽  
Endocrine Tissue ◽  
Pancreatic Islets Of Langerhans

Endocrine cell types are non-randomly distributed within pancreatic islets of Langerhans. In the rat, insulin-secreting B-cells occupy the core of the islets and are surrounded by A-, D- and PP-cells, secreting glucagon, somatostatin and pancreatic polypeptide, respectively. Furthermore, dissociated islet cells have the ability in vitro to form aggregates with the same cell-type organization as native islets (pseudoislets). These observations suggest that a differential expression of cell adhesion molecules (CAMs) might characterize B- and non-B-cells (A-, D- and PP-cells), and be in part responsible for the establishment and maintenance of islet architecture. Indirect immunofluorescence using antibodies against CAMs and islet hormones was performed on serial sections of the splenic and duodenal parts of the rat pancreas. Staining for the Ca(2+)-dependent CAM E-cadherin was detected on both exocrine and endocrine tissue and was uniform over the entire islet section, in both pancreatic regions. By contrast, staining for the Ca(2+)-independent neural CAM (N-CAM) was restricted to endocrine tissue and nerve endings. Furthermore, N-CAM staining of endocrine cells was stronger in the islet periphery, a region composed mostly of non-B-cells. Serial sections demonstrate that cells staining strongly for N-CAM in the splenic part correspond to glucagon cells and in the duodenal part to pancreatic polypeptide cells. Within pseudoislets in vitro a stronger staining for N-CAM was also observed on peripheral cells, corresponding to non-B-cells.

The pigmentary system of developing axolotls

Development ◽  
1984 ◽  
Vol 81 (1) ◽  
pp. 105-125
Author(s):  
S. K. Frost ◽  
L. G. Epp ◽  
S. J. Robinson
Keyword(s):  
Developmental Stages ◽  
Pigment Cell ◽  
Cell Types ◽  
Ambystoma Mexicanum ◽  
Pigment Cells ◽  
Wild Type ◽  
Cell Type ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Mutant Phenotypes

A biochemical and transmission electron microscopic description of the wild-type pigment phenotype in developing Mexican axolotls (Ambystoma mexicanum) is presented. There are three pigment cell types found in adult axolotl skin - melanophores, xanthophores and iridophores. Both pigments and pigment cells undergo specific developmental changes in axolotls. Melanophores are the predominant pigment cell type throughout development; xanthophores occur secondarily and in fewer numbers than melanophores; iridophores do not appear until well into the larval stage and remain thereafter as the least frequently encountered pigment cell type. Ultrastructural differences in xanthophore organelle (pterinosome) structure at different developmental stages correlate with changes in the pattern of pteridine biosynthesis. Sepiapterin, a yellow pteridine, is present in larval axolotl skin but not in adults. Ribofiavin (also yellow) is present in minimal quantities in larval skin and large quantities in adult axolotl skin. Pterinosomes undergo a morphological “reversion” at some point prior to or shortly after axolotls attain sexual maturity. Correlated with the neotenic state of the axolotl, certain larval pigmentary features are retained throughout development. Notably, the pigment cells remain scattered in the dermis such that no two pigment cell bodies overlap, although cell processes may overlap. This study forms the basis for comparison of the wild type pigment phenotype to the three mutant phenotypes-melanoid, axanthic and albino-found in the axolotl.

Micromorphometry, Cell Distribution and Ultrastructure of Some Immunopotent Leucocytes from Pronephric Kidney of Channa punctatus (Bloch)

2007 ◽  
Vol 20 (1) ◽  
Author(s):  
R. GHOSH ◽  
S. HOMECHAUDHURI
Keyword(s):  
West Bengal ◽  
Head Kidney ◽  
Cell Types ◽  
Channa Punctatus ◽  
Relative Distribution ◽  
Cell Distribution ◽  
Cell Type ◽  
Thin Sections ◽  
Glass Slides ◽  
Transmission Electron

Leucocytes in the pronephric head kidney of five Channa punctatus (Bloch 1793), from wetlands near Kolkata, West Bengal, India, were studied through stained imprints on glass slides for light microscopy, and fixed thin sections for transmission electron microscopy. The morphology, shape and size of the leucocytes – neutrophils, eosinophils, large and small lymphocytes and macrophages – and their nuclei are described. The relative distribution of the cell types were 37-47, 4-7, 18-24, 17-30 and 9-16%, respectively. The areas, in µm2, of each cell type and its nucleus are given. Macrophages are monocyte-like with well developed Golgi complex, pigments and intracytoplasmic vesicles and vacuoles.

scholarly journals Histomorphology of the ovaries of the earthworm, Dendrobaena atheca Cernosvitov (Annelida, Clitellata: Oligochaeta)

2017 ◽  
Vol 34 (03) ◽  
pp. 178-185 ◽  
Author(s):  
N. Gorgees ◽  
V. Khalid
Keyword(s):  
Stromal Cell ◽  
Germ Line ◽  
Cell Types ◽  
Internal Cavity ◽  
Specific Cell ◽  
Serial Sections ◽  
Cell Type ◽  
Breeding Seasons ◽  
Intercellular Connections ◽  
Comprehensive Study

AbstractThis comprehensive study was undertaken to reveal the ovarian histomorphology in the oligochaetous clitellte, Dendrobaena atheca Cernosvitov. Efforts were, in fact, made to obtain proper histological preparations. So, various types of thin serial sections of ovaries were carefully obtained, stained and examined. Two small ovaries, at the beginning of breeding seasons, were seen in segment thirteen. Subsequently, they extremely increased in size and became fully formed. They demonstrated six principal cell types: peritoneal cell, follicular cell, stromal cell, oogonium, oocyte and trophocyte (nurse cell). The first three cell types were somatic, whereas the other three were germ and germ-line. All cell types were, as much as possible, properly described. Dividing oogonia were seen to produce oocytes and trophocytes simultaneously. The produced cells were seen to be interconnected. The stromal cell, a newly described cell type, exhibited several specific cell characteristics. Ovaries showed no internal lumens. The small ovaries showed only two distinct histological zones, whereas the large ones showed three such zones. Germ and germ-line cells showed an obvious arrangement in ovarian zones. Accordingly, the chief conclusions are: (1) ovaries are nutrimental due to presence of trophocytes (2) ovaries are solid and not sac-like organs due the lack of internal cavity (3) stromal cell can be considered a new cell type as it demonstrates several specific cell features (4) Ovarian zonation is caused by production and arrangement of germ and germ-line cells (5) intercellular connections are due to incomplete cell divisions.

scholarly journals Spd-2 Gene Duplication Suggests Cell-Type Specific Assembly Mechanisms of Pericentriolar Material

2021 ◽  
Author(s):  
Ryan S O'Neill ◽  
Afeez Sodeinde ◽  
Frances C Welsh ◽  
Brian J Galletta ◽  
Carey J Fagerstrom ◽  
...  
Keyword(s):  
Gene Duplication ◽  
Somatic Cells ◽  
Cell Types ◽  
Male Meiosis ◽  
Gene Duplications ◽  
Cell Type ◽  
Male Germline ◽  
Pericentriolar Material ◽  
Cell Type Specific ◽  
Germline Cells

Centrosomes are multi-protein complexes that function as the major microtubule organizing center (MTOC) for the cell. While centrosomes play tissue-specific MTOC functions, little is known about how particular centrosome proteins are regulated across cell types to achieve these different functions. To investigate this cell type-specific diversity, we searched for gene duplications of centrosome genes in the Drosophila lineage with the aim of identifying centrosome gene duplications where each copy evolved for specialized functions. Through in depth functional analysis of a Spd-2 gene duplication in the Willistoni group, we discovered differences in the regulation of PCM in somatic and male germline cells. The parental gene, Spd-2A, is expressed in somatic cells, where it can function to organize pericentriolar material (PCM) and the mitotic spindle in larval brain neuroblasts. Spd-2A is absent during male meiosis, and even when ectopically expressed in spermatocytes it fails to rescue PCM and spindle organization. In contrast, the new gene duplicate, Spd-2B, is expressed specifically in spermatocytes. During male meiosis, Spd-2B localizes to centrosomes, organizes PCM and spindles, and is sufficient for proper male fertility. Experiments using chimeric transgenes reveal that differences in the C-terminal tails of Spd-2A and Spd-2B are responsible for these functional changes. Thus, Spd-2A and Spd-2B have evolved complementary functions by specializing for distinct subsets of cells. Together, our results demonstrate that somatic cells and male germline cells have fundamentally different requirements for PCM, suggesting that PCM proteins such as Spd-2 is differentially regulated across cell types to satisfy distinct requirements.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Dendritic cells of the human epidermis: immuno-electron microscopic studies of la antigen reactivity

1978 ◽  
Vol 36 (2) ◽  
pp. 644-645
Author(s):  
G. Rowden ◽  
M. G. Lewis ◽  
T. M. Phillips
Keyword(s):  
Dendritic Cells ◽  
Langerhans Cells ◽  
Cell Types ◽  
Cell Type ◽  
Electron Microscopic ◽  
La Antigen ◽  
Microscopic Studies ◽  
A Cell ◽  
C3 Receptors ◽  
Antigen Reactivity

Langerhans cells of mammalian stratified squamous epithelial have proven to be an enigma since their discovery in 1868. These dendritic suprabasal cells have been considered as related to melanocytes either as effete cells, or as post divisional products. Although grafting experiments seemed to demonstrate the independence of the cell types, much confusion still exists. The presence in the epidermis of a cell type with morphological features seemingly shared by melanocytes and Langerhans cells has been especially troublesome. This so called "indeterminate", or " -dendritic cell" lacks both Langerhans cells granules and melanosomes, yet it is clearly not a keratinocyte. Suggestions have been made that it is related to either Langerhans cells or melanocyte. Recent studies have unequivocally demonstrated that Langerhans cells are independent cells with immune function. They display Fc and C3 receptors on their surface as well as la (immune region associated) antigens.

Cell Reactivity Pattern of the Guinea Pig Cecal Mucosa Evidenced by the ZIO Technique

1982 ◽  
Vol 40 ◽  
pp. 50-51
Author(s):  
Juan Mora-Galindo ◽  
Jorge Arauz-Contreras
Keyword(s):  
Guinea Pig ◽  
Phase Contrast ◽  
Osmium Tetroxide ◽  
Cell Types ◽  
Cell Reactivity ◽  
Transmission Electron ◽  
Neural Tissues ◽  
Maturation Stages ◽  
Zinc Iodide ◽  
Cecal Mucosa

The zinc iodide-osmium tetroxide (ZIO) technique is presently employed to study both, neural and non neural tissues. Precipitates depends on cell types and possibly cell metabol ism as well.Guinea pig cecal mucosa, already known to be composed of epithelium with cells at different maturation stages and lamina propria which i s formed by morphologically and functionally heterogeneous cell population, was studied to determine the pat tern of ZIO impregnation. For this, adult Guinea pg cecal mucosa was fixed with buffered 1.2 5% g 1 utara 1 dehyde before incubation with ZIO for 16 hours, a t 4°C in the dark. Further steps involved a quick sample dehydration in graded ethanols, embedding in Epon 812 and sectioning to observe the unstained material under a phase contrast light microscope (LM) and a transmission electron microscope (TEM).

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