The effects of mating on the fine structure of neurosecretory caudodorsal cells in Helisoma duryi (Mollusca)

1990 ◽  
Vol 68 (6) ◽  
pp. 1233-1240 ◽  
Author(s):  
Hamid R. Khan ◽  
Mary Lou Ashton ◽  
Spencer T. Mukai ◽  
A. S. M. Saleuddin
Keyword(s):  
Electron Microscopy ◽  
Protein Synthesis ◽  
Fine Structure ◽  
Tannic Acid ◽  
Egg Laying ◽  
Electron Microscope Autoradiography ◽  
Large Numbers ◽  
Helisoma Duryi ◽  
Microscope Autoradiography ◽  
Silver Grains

The hermaphroditic snail Helisoma duryi does not lay eggs if raised as a virgin in isolation or when castrated. The fine structure of its neurosecretory caudodorsal cells (CDC), which produce the putative egg-laying hormone, was studied in reproductively inactive virgin and castrated snails and compared with that of the reproductively active mated snails, using electron microscopy, tannic acid incubation technique, and electron microscope autoradiography after injection of [3H]leucine. The CDC of virgin and castrated snails accumulate large numbers of elementary granules and appear synthetically inactive, whereas the CDC of mated snails contain fewer elementary granules and possess features characteristic of increased protein synthesis. The flattened cisternae of the rough endoplasmic reticulum of the CDC of the virgins become swollen 3 h after first mating. In tannic acid incubated tissues, more released granules were seen in CDC from snails 12 h after first mating than in CDC from virgin and castrated snails. Autoradiography showed more silver grains on the CDC from snails 12–48 h after first mating than on those from snails 3–6 h after first mating. It is suggested that, in Helisoma, mating provides a stimulus to the CDC for increased protein synthesis and release of the putative egg-laying hormone.

scholarly journals NUCLEAR ENVELOPE-ASSOCIATED RESUMPTION OF RNA SYNTHESIS IN LATE MITOSIS OF HELA CELLS

1973 ◽  
Vol 59 (1) ◽  
pp. 150-164 ◽  
Author(s):  
T. Simmons ◽  
P. Heywood ◽  
L. Hodge
Keyword(s):  
Protein Synthesis ◽  
Nuclear Envelope ◽  
Rna Synthesis ◽  
Electron Microscope Autoradiography ◽  
Molecular Synthesis ◽  
Hela S3 ◽  
Precursor Rna ◽  
Ribosomal Precursor ◽  
Hela S3 Cells ◽  
Silver Grains

The restitution of RNA synthesis in cultures progressing from metaphase into interphase (G1) has been investigated in synchronized HeLa S3 cells by using inhibitors of macro-molecular synthesis and the technique of electron microscope autoradiography. The rate of incorporation of radioactive uridine into RNA approached interphase levels in the absence of renewed protein synthesis. In contrast, maintenance of this rate in G1 was dependent upon renewed protein synthesis. Restoration of synthesis of heterogeneous nuclear RNA occurred under conditions that inhibited production of ribosomal precursor RNA. In autoradiographs of individual cells exposed to radioactive uridine, silver grains were first detected after nuclear envelope reformation at the periphery of the chromosome mass but before chromosomal decondensation. These data are consistent with the following interpretation. Multiple RNA polymerase activities persist through mitosis and are involved in the initiation of RNA synthesis in early telophase at sites on the nuclear envelope.

Electron microscope autoradiography of isolated molecules

1978 ◽  
Vol 36 (2) ◽  
pp. 192-193
Author(s):  
M. Bouteille ◽  
E. Delain ◽  
N. Angelier
Keyword(s):  
Electron Microscope ◽  
High Efficiency ◽  
Specific Activity ◽  
Molecular Complexes ◽  
Electron Microscope Autoradiography ◽  
Microscope Autoradiography ◽  
Loop Technique ◽  
Silver Grains ◽  
Isolated Molecules

The LIGOP method of electron microscope autoradiography which consists in a combination of coating Ilford emulsion with the loop technique and developing with gold latensification and phenidon has proved to provide small, compact developed silver grains with high efficiency.This has made it possible to use this technique with very small materials such as isolated molecules of molecular complexes.The method was assayed first with 3H-Thymidine labelled T7 phages DNA molecule with 630,000 cpm/μg specific activity (fig. 1). The molecules were spread using the adsorption technique constrasted by rotatory shadowing with platinum and then subjected to autoradiography. The Labelling was sufficient to obtain quantitative data in which the spread molecules were considered as a material comparable to a “hot line”. The efficiency (45%) and the HD value (1600 Å) were calculated.The method was also applied to transcription units of pleurodeles oocytes nucleoli (fig. 2) labelled in vitro with 3H-Uridine.

The Cytoplasmic Incorporation of Tritiated Thymidine During Oogenesis in Pteridium Aquilinum

1971 ◽  
Vol 8 (2) ◽  
pp. 467-487
Author(s):  
D. C. SIGEE ◽  
P. R. BELL
Keyword(s):  
Electron Microscope ◽  
Tritiated Thymidine ◽  
Pteridium Aquilinum ◽  
Egg Cell ◽  
Cell Periphery ◽  
Short Term ◽  
Electron Microscope Autoradiography ◽  
Microscope Autoradiography ◽  
Silver Grains ◽  
Stable Molecule

The short-term incorporation of tritiated thymidine into the cytoplasm of cells undergoing oogenesis was investigated in Pteridium aquilinum using electron-microscope autoradiography. There was substantial uptake into the central cell and egg cell during the 6-h labelling period. The quantity and distribution of the label incorporated into the cytoplasm were closely similar in cells fixed immediately after the labelling period and in those immersed for a further 18 h in unlabelled thymidine. This suggested that incorporation was into a stable molecule, with little nucleoside turnover and no subsequent migration within the cytoplasm. Enzyme studies indicated that the tritiated thymidine was incorporated almost entirely into DNA, most probably the DNA undergoing replication. Within the cytoplasm the label was markedly and consistently concentrated in plastids and mitochondria. This localization was not, however, complete and 5-40% was attributable to sites in the ground cytoplasm. A gradient of incorporated label was demonstrated within the cytoplasm in both central cells and egg cells. Concentration was high adjacent to the nucleus and low at the cell periphery. This gradient could be satisfactorily explained by the distribution of the plastids and mitochondria within the cytoplasm, the labelling of the organelles being irrespective of their position. The results of statistical examination of the frequencies of the silver grains associated with the mitochondria and plastids were considered to indicate general uptake of label directly into the DNA of these organelles without nuclear participation.

scholarly journals Cytological events involved in protein synthesis in cellular and syncytial trophoblast of human placenta. An electron microscope autoradiographic study of [3H]leucine incorporation.

1978 ◽  
Vol 76 (2) ◽  
pp. 400-417 ◽  
Author(s):  
D M Nelson ◽  
A C Enders ◽  
B F King
Keyword(s):  
Protein Synthesis ◽  
Electron Microscope ◽  
Autoradiographic Study ◽  
Leucine Incorporation ◽  
Electron Microscope Autoradiography ◽  
Placental Villi ◽  
Microscope Autoradiography ◽  
Syncytial Trophoblast ◽  
Time Point

Electron microscope autoradiography has been used to study protein synthesis in syncytial and cellular trophoblast of term human placental villi incubated in vitro with tritiated leucine ([3H]leu). Autoradiographs were analyzed using the hypothetical grain analysis of Blackett and Parry (1973. J. Cell Biol. 57:9-15). The results of this study demonstrated that both cellular and syncytial trophoblast have marked capacities for protein synthesis. Cellular trophoblast synthesized protein in both its rough endoplasmic reticulum (RER) and its ground plasm which contained abundant free ribosomes. The vast majority of 3H-proteins remained within the cell, with some of the proteins synthesized ultimately appearing in the nucleus. A small percentage of grains was ultimately associated with the trophoblast basement membrane. In syncytial trophoblast, the RER was the dominant site for protein synthesis. The autoradiographic data suggested that, as in the cellular trophoblast, the vast majority of 3H-proteins synthesized by the syncytial trophoblast remained within the syncytial trophoblast throughout the incubation period. The major portion of [3H]leu-labeling present in the syncytial trophoblast of villi incubated the longest times (4 h+) remained in association with the RER. Labeled proteins did not become concentrated in syncytial trophoblast Golgi apparatus, vesicles, or granules. In contrast to cellular trophoblast, the nuclei in the syncytium did not contain 3H-proteins at any time-point studied.

Structure of the “Core” Particles from 50S IS. coli Ribosomes Depleted by LiCl.

1976 ◽  
Vol 34 ◽  
pp. 66-67
Author(s):  
E. Spiess ◽  
H.E. Roth ◽  
W. Hellmann ◽  
F. Jenkins ◽  
M. Boublik
Keyword(s):  
Electron Microscopy ◽  
Protein Synthesis ◽  
Fine Structure ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Ribonucleic Acids ◽  
Detailed Mechanism ◽  
The Core ◽  
Resolution Electron ◽  
Approaches To Study

Involvement of ribosomes in protein synthesis is well established. Also substantial data about the roles of both ribosomal constituents, proteins and ribonucleic acids, in this process are known. However, the detailed mechanism of the function of ribosomes remains obscure, mainly because of our limited knowledge of the interactions and structural arrangement of ribosomal components.One of the approaches to study ribosome structure involves progressive depletion of proteins and correlation of the protein-depleted ribonucleoprotein cores with function. High resolution electron microscopy has been applied for direct imaging of the changes in the fine structure of depleted ribosomes.

Quantitation of Fluorophosphate - Reactive Esterase Sites in Rat Liver Using Electron Microscope Autoradiography

1975 ◽  
Vol 33 ◽  
pp. 466-467
Author(s):  
G. C. Budd
Keyword(s):  
Electron Microscope ◽  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Average Concentration ◽  
Electron Microscope Autoradiography ◽  
Cytoplasmic Granules ◽  
Diisopropyl Fluorophosphate ◽  
Microscope Autoradiography ◽  
Cytoplasmic Structures ◽  
Silver Grains

Following the application of 10-4 molar tritium labeled diisopropyl fluorophosphate (3H-DFP) to fresh or glutaraldehyde fixed rat liver, fluorophosphate-reactive (FPR) sites within the hepatocytes were measured using quantitative electron microscope autoradiography (EMARG). Based on the distribution of autoradiographic silver grains, most of the FPR sites were concentrated in the rough and smooth endoplasmic reticulum and associated ground cytoplasm. Cytoplasmic granules, comprising autophagic and residual granules also contained FPR sites. The average concentration of sites within each of these cytoplasmic structures was obtained from combined morphometric and grain density analyses of the EMARGs and light microscope sections of the same epoxy embedded liver specimens.

scholarly journals Secretory kinetics in the follicular cells of silkmoths during eggshell formation.

1978 ◽  
Vol 78 (1) ◽  
pp. 131-151 ◽  
Author(s):  
H M Blau ◽  
F C Kafatos
Keyword(s):  
Developmental Stages ◽  
Follicular Epithelium ◽  
Follicular Cells ◽  
Electron Microscope Autoradiography ◽  
Microscope Autoradiography ◽  
Rapid Accumulation ◽  
Photometric Measurements ◽  
Kinetics Of ◽  
Silver Grains ◽  
Apical Area

Procedures for quantitative autoradiography were used for studying the process of secretion of eggshell (chorion) proteins in the follicular epithelium of silkmoths. The method was based on photometric measurements of the reflectance of vertically illuminated autoradiographic silver grains. Results were analyzed and plotted by computer. Secretory kinetics were also determined by analysis of labeled proteins in physically separated epithelium and chorion. Rapid accumulation of radioactivity into "clumps" visualized by light microscope autoradiography and evidence from preliminary electron microscope autoradiography indicate that, within 2 min from the time of synthesis, labeled chorion proteins move to Golgi regions scattered throughout the cytoplasm. The proteins begin to accumulate in the apical area 10-20 min later and to be discharged from the cell. The time for half-secretion is 20-25 min, and discharge is essentially complete 30-50 min after labeling. At the developmental stages examined, the kinetics of secretion appear to be similar for all proteins. Within the chorion the proteins rapidly assume a characteristic distribution, which varies for different developmental stages. Two relatively slow steps have been identified in secretion, associated with residence in Golgi regions and in the cell apex, respectively. By contrast, translocation of proteins across the cell and deposition of discharged proteins in the chorion are rapid steps.

The secretion of the eggshell of Schistocerca gregaria, analysis of the kinetics of secretion in vitro by light and electron microscope autoradiography

1981 ◽  
Vol 50 (1) ◽  
pp. 225-243
Author(s):  
S.J. Kimber
Keyword(s):  
Electron Microscope ◽  
Schistocerca Gregaria ◽  
Similar Rate ◽  
Follicle Cells ◽  
Electron Microscope Autoradiography ◽  
Golgi Bodies ◽  
Microscope Autoradiography ◽  
Grain Distribution ◽  
Silver Grains

The secretion of the 2 main layers (endochorion and exochorion) of the eggshell of the desert locust Schistocerca gregaria was investigated using light and electron microscope autoradiography. Follicles undergoing endochorion secretion were labelled using a 3 min ‘pulse’ of [3H]leucine in vitro followed by a 0-115 min non-radioactive ‘chase’. Immediately after the pulse the silver grains were distributed over the cytoplasm and organelles including rough endoplasmic reticulum, while by 2 and 5 min Golgi bodies contained radioactivity. By 12 min from the beginning of the chase the cell apex containing small secretory vesicles was labelled. By 20 min most of the silver grains were over the endochorion. The half-transport time (t50) was 14–15 min (from mid pulse), the lag time was 9–10 min and the percentage transport rate was 14–15% per min. When a 3 min pulse of [3H]galactose was used to label exochorion precursors, the shorter t50 (11 min) and the clumped grain distribution in light microscope autoradiographs after 0-min chase suggested that galactose was incorporated in Golgi bodies. The secretion of exochorion precursors appears to occur at a similar rate to that of endochorion precursors (approximately 15% per min). The results indicate that the follicle cells are among the fastest secreting cells.

Fine structure of the giant cells induced by Meloidogyne javanica in lima bean

1984 ◽  
Vol 62 (3) ◽  
pp. 429-436 ◽  
Author(s):  
F. Fattah ◽  
J. M. Webster
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Light And Electron Microscopy ◽  
Lima Bean ◽  
Meloidogyne Javanica ◽  
Giant Cells ◽  
Egg Laying ◽  
Phaseolus Lunatus ◽  
Wide Range

Giant cells associated with egg-laying females of Meloidogyne javanica in lima bean, Phaseolus lunatus cv. L-136, were examined by light and electron microscopy. These giant cells have characteristics that are typical of nematode-induced giant cells in a wide range of hosts, but they differ in that they (i) are less closely associated with xylem vessels, (ii) contain a very large number of plastids which are devoid of starch grains, and (iii) contain several different forms of cytoplasmic crystals. One form of the crystal is associated with a large number of "spiny" vesicles. The possible role of these features, especially the crystals, in the giant cell response of lima bean is discussed.

Comparative morphology and fine structure of a group of Umbilicaria lichens

1984 ◽  
Vol 62 (9) ◽  
pp. 1947-1964 ◽  
Author(s):  
Martha G. Scott ◽  
Douglas W. Larson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Gas Exchange ◽  
Comparative Morphology ◽  
The Other ◽  
Bright Field ◽  
Structure And Morphology ◽  
Transmission Electron ◽  
Large Numbers

The gross morphology and fine structure of tissue layers in five Umbilicaria species (U. vellea, U. mammulata, U. papulosa, U. muhlenbergii, and U. deusta) were examined using bright-field and transmission electron microscopy. Differences in the surface topography of the upper and lower cortexes of the five species were found. Four of the species contained an osmiophilic banding material on the walls of the outermost file of living upper cortical hyphae. Although the fine structure of phycobiont cells was basically similar for all species, U. vellea was found to have smaller amounts of stored starch and peripheral lipid in cells of the algal zone than the other four species. Algal–fungal contacts were not haustorial, although aplanospore clusters were penetrated by wedge-shaped intrusive hyphae. Senescent algal cells accumulated large numbers of starch grains. Hyphae in the medullary zones were found to be similar for all species with the exception of U. muhlenbergii, which had an extrahyphal, gel-like matrix. Extensive, sheetlike lamellae were also present in the lower cortex of this species. It would appear that many aspects of thallus fine structure and morphology have a direct effect on gas exchange and water relations responses previously reported in the literature.

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