Centrosomes are phosphorylated in sea urchin eggs throughout the cell cycle, during artificial activation, and when microtubule growth is inhibited

1994 ◽  
Vol 52 ◽  
pp. 296-297
Author(s):  
Heide Schatten ◽  
Amitabha Chakrabarti
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Sea Urchin ◽  
Immunofluorescence Microscopy ◽  
Mitotic Apparatus ◽  
Zygote Nucleus ◽  
Transmission Electron ◽  
Microtubule Growth ◽  
Artificial Activation

In most animal systems, microtubules are nucleated and organized by centrosomes which undergo considerable modifications during the cell cycle. Typically, centrosomes are phoshorylated at the transition from interphase to mitosis as shown with MPM2, an antibody directed against phosphoproteins. Using the MPM2 antibody, we show in this paper with transmission electron microscopy (TEM) and immunofluorescence microscopy (IFM) that in the sea urchin system centrosomes are phosphorylated in the sperm before fertilization and at every stage of the first cell cycle. MPM2 exhibits identical staining patterns as Ah-6 and 5051 previously shown to reliably identify centrosomal material in sea urchin cells. After centrosomal material is brought into the egg by the sperm, it spreads around the zygote nucleus where it gets distributed and becomes bipolar and compacted to form the mitotic apparatus. Typically, at these mitotic stages, centrosomal material exhibits the brightest staining with MPM2, Ah-6 and 5051 Since in this system phoshorylated centrosomal material is contributed by the sperm, the egg's competence for centrosome phosphorylation was analyzed by activating centrosomal material in the unfertilized egg by treatment with either A23187, ammonia, D2O, or taxol.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Producing exposed cota-free embryos

Zygote ◽  
1994 ◽  
Vol 2 (3) ◽  
pp. 221-225 ◽  
Author(s):  
Michael F. Daily ◽  
Virginia H. Latham ◽  
Claudia M. Garcia ◽  
Cynthia L. Hockman ◽  
Helen Chun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sea Urchin ◽  
Alpha Amylase ◽  
Lectin Receptors ◽  
Lytechinus Pictus ◽  
Amylase Inhibitor ◽  
Transmission Electron ◽  
Alpha Amylase Inhibitor

SummaryProduction of embryos that are free of tough outer coats facilitates studies that are not possible with embryos surrounded by impenetrable envelopes. This report describes a new procedure for preventing formation of fertilisation membranes in the sea urchin (Lytechinus pictus) model. This procedure involves treating unfertilised eggs with the enzyme alpha-amylase, which cleaves alpha-1,4 glucosidic bonds in the vitelline layer. A major advantage of this method is that it is very well defined and completely controllable with alpha-amylase inhibitor. The results suggest that intact alpha-1,4 glucosidic bonds are essential for vitelline layer integrity required for formation of the fertilisation membrane. Eggs treated with alpha-amylase possessed the same surface lectin receptors as untreated eggs and, as shown by light and transmission electron microscopy, produced healthy, cleaving embryos that were free of fertilisation envelopes.

Morphology-Controlled Synthesis of Single Crystalline α-Mn2O3 Sea-Urchins Assembled with Pen-Type Nanoneedles and Broad Absorption Spectrum

2015 ◽  
Vol 33 ◽  
pp. 38-48 ◽  
Author(s):  
Qurat Ul Ain Javed ◽  
Hussain Abbas ◽  
Hasan Mahmood ◽  
Abdul Sattar ◽  
Feng Ping Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Experimental Conditions ◽  
Hydrothermal Temperature ◽  
Single Crystalline ◽  
X Ray ◽  
Transmission Electron ◽  
Uv Visible

Single crystalline high quality α-Mn2O3nanorods and sea-urchins assembled with pen-type nanoneedles have been successfully synthesized by template-free hydrothermal route. The variation in hydrothermal temperature has affected the morphology of the α-Mn2O3sea-urchin assembled with the nanoneedles noticeably. The influence of temperature change on the thickness, crystallinity, surface morphology and optical properties of α-Mn2O3has been characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis, Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), Raman Spectroscopy (RS) and UV-visible Spectroscopy. The results showed that in our experimental conditions, single crystalline nanorods of the α-Mn2O3were obtained at a low temperature of 180 °C, while single crystalline sea-urchin assembled with pen-type nanoneedles were obtained by increasing the temperature to 280 °C. Nanorods and sea-urchin assembled with pen-type nanoneedles obtained had the well defined morphology and crystalline quality. The sea-urchin synthesized at 280 °C exhibited more than 90% absorption in UV-visible spectrum.

Selective resorption in nutritive phagocytes of the sea urchin Anthocidaris crassispina

Zygote ◽  
2004 ◽  
Vol 12 (1) ◽  
pp. 71-73 ◽  
Author(s):  
Arkadiy A. Reunov ◽  
Alexander V. Kalachev ◽  
Olga V. Yurchenko ◽  
Doris W.T. Au
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sea Urchin ◽  
Sperm Cells ◽  
Transmission Electron ◽  
Residual Bodies ◽  
Anthocidaris Crassispina

Phagocytic resorption during spermatogenesis was studied in the sea urchin Anthocidaris crassispina. Nutritive phagocytes in gonad absorbed both waste sperm cells and residual bodies discarded from maturing spermatids, and these materials were subsequently compartmented in heterophagosomes. Based on 180 heterophagosomes examined by transmission electron microscopy, over 99% of heterophagosomes contained either residual bodies or sperm cells only. Simultaneous resorption of sperm cells and residual bodies in a heterophagosome was uncommon, with only ∼0.56% occurrence, suggesting that heterophagosomes have a selective resorption ability in nutritive phagocytes.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

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