Centrosome inheritance in starfish zygotes: behaviour and duplicating capacity of the meiotic centrosomes in maturation division

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S12-S13
Author(s):  
Miwa Tamura ◽  
Shin-ichi Nemoto
Keyword(s):  
Polar Body ◽  
Ionophore A23187 ◽  
Differential Interference Contrast Microscopy ◽  
Centriole Duplication ◽  
Polar Bodies ◽  
Transmission Electron ◽  
Interference Contrast Microscopy ◽  
Almost All ◽  
Artificial Activation ◽  
Asterina Pectinifera

In zygotes of almost all animals, it has been believed that only the sperm centrosome acts as the mitotic spindle poles. As first proposed a century ago by Boveri (1887), this uniparental (paternal) inheritance of the centrosome must depend on the selective loss of the maternal centrosomes. To trace the fate and duplicating capacity of all the maternal centrosomes/centrioles, including those cast off into polar bodies, we used two kinds of procedures: (1) suppression of polar body (PB) extrusion and (2) transplantation of PB centro-somes into artificially activated eggs.Gametes used in this study were from the starfish, Asterina pectinifera. Oocyte maturation was induced with 1-methyladenine (Kanatani, 1969). Suppression of PB extrusion and artificial activation were done according to Washitani-Nemoto et al. (1994). Micromanipulation was performed by the method of Saiki & Hamaguchi (1993). Behaviour of the centrosomes was examined by staining with an antibody against α-tubulin, polarisation and differential interference-contrast microscopy and transmission electron microscopy.In starfish oocytes, no centriole duplication occurs in meiosis II, hence each pole of a meiosis II spindle is formed by the splitting of paired centrioles in the inner centrosome of a meiosis I spindle into singles. Eventually, each of a second PB (PB2) and a mature egg inherits only one centriole from a meiosis II spindle (a PB1 inherits a pair of centrioles). So, either PB2 and the mature egg inherit a single centriole (Fig. 1; cf. Sluder et al., 1989; Kato et al., 1990). When mature eggs were artificially activated with the Ca2+-ionophore A23187, a single monaster was formed.

scholarly journals Studies on the motility of the foraminifera. II. The dynamic microtubular cytoskeleton of the reticulopodial network of Allogromia laticollaris.

1983 ◽  
Vol 97 (6) ◽  
pp. 1668-1676 ◽  
Author(s):  
J L Travis ◽  
J F Kenealy ◽  
R D Allen
Keyword(s):  
Polarized Light ◽  
Differential Interference Contrast ◽  
Differential Interference Contrast Microscopy ◽  
Transmission Electron ◽  
Microtubular Cytoskeleton ◽  
Whole Mount ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy ◽  
Birefringent Fibrils ◽  
Positively Charged

Lamellipodia have been induced to form within the reticulopodial networks of Allogromia laticollaris by being plated on positively charged substrata. Video-enhanced, polarized light, and differential interference contrast microscopy have demonstrated the presence of positively birefringent fibrils within these lamellipodia. The fibrils correspond to the microtubules and bundles of microtubules observed in whole-mount transmission electron micrographs of lamellipodia. Microtubular fibrils exhibit two types of movements within the lamellipodia: lateral and axial translocations. Lateral movements are often accompanied by reversible lateral associations between adjacent fibrils within a lamellipodium. This lateral association-dissociation of adjacent fibrils has been termed 'zipping' and 'unzipping'. Axial translocations are bidirectional. The axial movements of the microtubular fibrils can result in the extension of filopodia by pushing against the plasma membrane of the lamellipodia. Shortening, or complete withdrawal, of such filopodia is accomplished by the reversal of the direction of the axial movement. The bidirectional streaming characteristic of the reticulopodial networks also occurs within the lamellipodia. In these flattened regions the streaming is clearly seen to occur exclusively in association with the intracellular fibrils. Transport of both organelles and bulk hyaline cytoplasm occurs bidirectionally along the fibrils.

Role of the fertilisation envelope and specialised microvilli in morphogenesis of starfish embryos

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S65-S65
Author(s):  
Maki Matsunaga ◽  
Isao Uemura ◽  
Miwa Tamura ◽  
Shin-ichi Nemoto
Keyword(s):  
Sea Urchin ◽  
Three Dimensional ◽  
Immunofluorescent Staining ◽  
Differential Interference Contrast Microscopy ◽  
Early Cleavage ◽  
Sea Urchin Embryos ◽  
Interference Contrast Microscopy ◽  
Cleavage Stages ◽  
To Come ◽  
Asterina Pectinifera

In the early cleavage stages of animal embryos, blas-tomeres lack devices to connect to each other. It is well known that in sea urchin embryos the hyaline layer plays an important role in maintaining the position of individual blastomeres, and provides a scaffold for morphogenesis to the embryo. In starfish embryos, however, the presence of the hyaline layer is not certain in the early cleavage stages, although it has been observed at the gastrula stage (Dan-Sohkawa et al., 1986). In the present study we have investigated the devices corresponding to the hyaline layer of sea urchin embryos in the early cleavage stages, where blastomeres lack such devices for cell adhesion as desmosomes.We examined how blastomeres keep their position in the early cleavage stages of starfish embryos using Asterina pectinifera and Astropecten scoparius. By neither electron microscopy nor immunofluorescent staining with an antibody against the hyaline layer of sea urchin embryos (Yazaki, 1968) could we detect the hyaline layer, at least up to 6 h after fertilisation.When the fertilisation envelope (FE) was dilated larger by urea treatment, blastomeres increasingly came apart with the expansion of the FE, resulting in the formation of plural small blastulae due to the failure of the blastomeres to come together into a single mass. In urea-treated embryos, blastomeres were observed closely apposed to the inner surface of the FE. These observations suggest that blastomeres are fixed by some means to the FE. Differential interference-contrast microscopy revealed numerous projections between the cell surface of the blastomeres and the FE. Probably, the FE and the projections are involved in maintaining the three-dimensional position of each blastomere in an embryo.

Establishment of embryonic axes in larvae of the starfish, Asterina pectinifera

Development ◽  
1983 ◽  
Vol 75 (1) ◽  
pp. 87-100
Author(s):  
Tetsuya Kominami
Keyword(s):  
Cleavage Plane ◽  
Anterior Part ◽  
Polar Body ◽  
Cleavage Pattern ◽  
Early Cleavage ◽  
Embryonic Axes ◽  
Cell Stage ◽  
Polar Bodies ◽  
Asterina Pectinifera ◽  
Fertilized Egg

In order to clarify the relationships between the first cleavage plane and the embryonic axes, early cleavage pattern of the fertilized eggs of the starfish, Asterina pectinifera was reexamined . It was ascertained that the polar bodies were formed at the site to which the germinal vesicle had closely located before the initiation of the meiotic division, and that the first cleavage plane passed near this site of polar body formation. While some of the early embryos of this starfish were observed to show various cleavage patterns during early cleavage stage, more than 70% of the embryos developed according to, so to say, the ‘typical’ cleavage pattern. Next, horseradish peroxidase (HRP) was injected into one of the blastomeres of the 2-cellor 8-cell-stage embryos. The embryos were allowed to develop up to either the early gastrula or the early bipinnaria stage and stained to detect the descendants of the blastomere injected with HRP. In early gastrulae still retaining radial symmetry, the activity of HRP injected at the 2-cell stage was found only in one side of the embryo partitioned by one of the symmetrical planes. When one of the four blastomeres lying nearer to the polar bodies at the 8-cell stage was marked with HRP, its descendants constituted one quarter of the anterior part of the gastrula, and descendants of a blastomere opposite the polar bodies were found in the posterior region of the embryo. It was concluded that the animal-vegetal (AV) axis was preexisting in the fertilized egg and that the first cleavage plane contained this primary axis. In early bipinnariae with their dorsoventral (DV) axes already established, the region of activity of the HRP injected at the 2-cell stage was still demarcated by a plane which passed through the AV axis, but the plane of the boundary had no fixed relation to the DV axis. The results indicate that the first cleavage plane does not necessarily correspond to the median plane of the starfish larva, unlike the case in sea-urchin eggs (Hörstadius & Wolsky, 1936). In other words, the DV axis of the starfish embryo is not predetermined in the fertilized egg, and might be established in the course of development through cell-to-cell interactions, while the AV axis is established mainly according to the pre-existing egg polarity.

The size of extracellular vesicles secreted by different types of stem cells

2018 ◽  
pp. 38-42
Author(s):  
И.Б. Алчинова ◽  
М.В. Полякова ◽  
И.Н. Сабурина ◽  
М.Ю. Карганов
Keyword(s):  
Stem Cells ◽  
Extracellular Vesicles ◽  
Culture Media ◽  
Living Organism ◽  
Isolation And Characterization ◽  
Transmission Electron ◽  
Study Results ◽  
Multipotent Mesenchymal Stem Cells ◽  
Rat Adipose Tissue ◽  
Almost All

Механизм терапевтического действия мультипотентных мезенхимных стволовых клеток (ММСК) на облученный организм в последнее время вызывает повышенный интерес исследователей. В качестве активного участника паракринного механизма реализации этого эффекта предлагают рассматривать внеклеточные везикулы, секретируемые практически всеми клетками живого организма. Цель работы: выделить и охарактеризовать внеклеточные везикулы, продуцируемые стволовыми клетками различной природы. Материалы и методы. Суспензии внеклеточных везикул, выделенных по модифицированному протоколу дифференциального центрифугирования из культуральных жидкостей от культур ММСК костного мозга человека 2-го пассажа и ММСК жировой ткани крысы 4-го пассажа, были проанализированы методом просвечивающей электронной микроскопии и методом анализа траекторий наночастиц. Результаты. Исследование показало наличие в обоих образцах микрочастиц размерами до и около 100 нм, однако процентное содержание частиц разных размеров в суспензии различалось для двух анализируемых типов клеток. Заключение. Полученные результаты могут свидетельствовать о специфике секреции, обусловленной клеточным типом. A mechanism of the therapeutic effect of multipotent mesenchymal stem cells (MMSC) on irradiated body has recently arisen much interest of researchers. Extracellular vesicles (EVs) secreted by almost all cells of a living organism were suggested to actively contribute to the paracrine mechanism of this effect. The aim of the study was isolation and characterization of extracellular vesicles produced by various types of stem cells. Materials and methods. Suspensions of EVs were isolated from culture media of passage 2 human bone marrow-derived MMSC and passage 4 rat adipose tissue-derived MMSC using a modified protocol of differential centrifugation and then studied using transmission electron microscopy and nanoparticle tracking analysis. Results. The study showed the presence of microparticles with a size of >100 nm in the examined samples. However, the percent content of particles with different sizes in the suspension was different in two analyzed types of cell culture. Conclusion. The study results might reflect a specificity of secretion determined by the cell type.

Utilizing Nanoprobing and Circuit Diagnostics to Identify Key Failure Mechanism of Otherwise Nonvisible Defects in 20 nm Logic Devices

2014 ◽  
Author(s):  
M.K. Dawood ◽  
C. Chen ◽  
P.K. Tan ◽  
S. James ◽  
P.S. Limin ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Contact Layer ◽  
Fault Isolation ◽  
Tem Analysis ◽  
Logic Devices ◽  
Technology Advancement ◽  
Transmission Electron ◽  
Voltage Contrast ◽  
Almost All ◽  
20 Nm

Abstract In this work, we present two case studies on the utilization of advanced nanoprobing on 20nm logic devices at contact layer to identify the root cause of scan logic failures. In both cases, conventional failure analysis followed by inspection of passive voltage contrast (PVC) failed to identify any abnormality in the devices. Technology advancement makes identifying failure mechanisms increasingly more challenging using conventional methods of physical failure analysis (PFA). Almost all PFA cases for 20nm technology node devices and beyond require Transmission Electron Microscopy (TEM) analysis. Before TEM analysis can be performed, fault isolation is required to correctly determine the precise failing location. Isolated transistor probing was performed on the suspected logic NMOS and PMOS transistors to identify the failing transistors for TEM analysis. In this paper, nanoprobing was used to isolate the failing transistor of a logic cell. Nanoprobing revealed anomalies between the drain and bulk junction which was found to be due to contact gouging of different severities.

scholarly journals Facile synthesis of Au/ZnO/Ag nanoparticles using Glechoma hederacea L. extract, and their activity against leukemia

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Renata Dobrucka ◽  
Aleksandra Romaniuk-Drapała ◽  
Mariusz Kaczmarek
Keyword(s):  
Electron Microscopy ◽  
Ag Nanoparticles ◽  
Mononuclear Cells ◽  
Leukemia Cell ◽  
Leukemia Cell Line ◽  
Mtt Test ◽  
Transmission Electron ◽  
Almost All ◽  
Glechoma Hederacea

AbstractMetal combinations have been attracting the attention of scientists for some time. They usually exhibit new characteristics that are different from the ones possessed by their components. In this work, Au/ZnO/Ag nanoparticles were synthesized biologically using Glechoma hederacea L. extract. The synthesized Au/ZnO/Ag nanoparticles were characterized by UV-Vis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Atomic Force Microscopy (AFM). The microscopic methods confirmed the presence of spherical nanoparticles of 50–70 nm. The influence of biologically synthesized Au/ZnO/Ag nanoparticles on the vitality of human cells was evaluated in vitro with the use of established human Acute T Cell Leukemia cell line, Jurkat (ATCC® TIB-152™), as well as mononuclear cells isolated from peripheral blood (PBMC) of voluntary donors. Cell survival and the half-maximal inhibitory concentration index (IC50) were analyzed by the MTT test. The studies showed that the total loss of cell viability occurred at the Au/ZnO/Ag nanoparticle concentration range of 10 µmol–50 µmol. The use of Au/ZnO/Ag nanoparticles at the concentration of 100 µmol eliminated almost all living cells from the culture in 24h. The above observation confirms the result obtained during the MTT test.

scholarly journals Minus-end capture of preformed kinetochore fibers contributes to spindle morphogenesis

2003 ◽  
Vol 160 (5) ◽  
pp. 671-683 ◽  
Author(s):  
Alexey Khodjakov ◽  
Lily Copenagle ◽  
Michael B. Gordon ◽  
Duane A. Compton ◽  
Tarun M. Kapoor
Keyword(s):  
Three Dimensional ◽  
Differential Interference Contrast ◽  
Differential Interference Contrast Microscopy ◽  
Spindle Formation ◽  
Capture Mechanism ◽  
Contrast Microscopy ◽  
Interference Contrast Microscopy ◽  
Kinesin Eg5 ◽  
Mitotic Kinesin Eg5 ◽  
Dependent Mechanism

Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living α-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established a transient chromosome-free bipolar array whose orientation specified the axis along which chromosomes segregated. We propose that the capture and incorporation of preformed K-fibers complements the microtubule plus-end capture mechanism and contributes to spindle formation in vertebrates.

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