EFFETS DES MICROIRRADIATIONS SUR LES MICROSPOROCYTES ET MICROSPORES DE TRADESCANTIA PALUDOSA. III. NOTE PRÉLIMINAIRE SUR LES EFFETS DES MICROIRRADIATIONS ULTRAVIOLETTES

1973 ◽  
Vol 15 (1) ◽  
pp. 39-44
Author(s):  
G. Garot ◽  
M. Dujardin ◽  
A. Gilles
Keyword(s):  
Chromosome Structure ◽  
Interphase Nuclei ◽  
Remarkable Effect ◽  
Anaphase Bridges ◽  
Selective Destruction ◽  
Tradescantia Paludosa

Microsporocytes of Tradescantia paludosa have been irradiated with ultraviolet microbeams of 2 to 10 microns. At a wavelength of 2570 A, we observe a selective destruction, total or partial, of the spindle in the first division, anaphase bridges and interruption in the second division.At a wavelength of 2750 A, the most remarkable effect is the "paling" of some parts of the chromosome structure as well as of interphase nuclei, and also stickiness bridges in the bivalents of the first division.

Nuclear proteins of quiescent and mitotically active cells in shoot meristems of Tradescantia paludosa

1974 ◽  
Vol 52 (9) ◽  
pp. 2049-2053 ◽  
Author(s):  
R. S. Tobin ◽  
Kyu-Byung Yun ◽  
J. M. Naylor
Keyword(s):  
Nuclear Proteins ◽  
Zone Of Inhibition ◽  
Interphase Nuclei ◽  
Lateral Buds ◽  
Dye Binding ◽  
Tradescantia Paludosa ◽  
Shoot Meristems

In inhibited lateral buds of Tradescantia paludosa, interphase nuclei in the apical zone of inhibition contain higher levels of arginine per unit DNA than those of mitotically active cells in interphase or prophase. Supplementary dye-binding experiments suggest that this reflects a corresponding difference between the composition of the histone complement of chromatin in the two cells populations. The possible implications of this phenomenon are discussed.

New Insights Into the Three-Dimensional Structure of the Nucleus and Chromosomes

1997 ◽  
Vol 3 (S2) ◽  
pp. 213-214
Author(s):  
J. Sedat ◽  
W. Marshall ◽  
A. Dernburg ◽  
J. Fung ◽  
D. Agard
Keyword(s):  
Chromosome Structure ◽  
Position Effect ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Position Effect Variegation ◽  
Genetic Loci ◽  
Interphase Nuclei ◽  
Intact Cells ◽  
3 Dimensional ◽  
Specific Localization

Recent methodology, to be described, now makes possible specific localization and analysis of genetic loci within 3-Dimensional interphase nuclei in intact cells and tissues with minimal perturbation of the chromosome structure (Dernburg and Sedat, 1997). These techniques define genetic loci that specifically interact with the nuclear envelope and interior structures; we are able to map all loci to highly localized 3-dimensional positions within Drosophila embryonic nuclei (Marshall et al, 1996). S-Dimensions-as-a-function-of-time (4-D) studies of live nuclei, from Yeast and Drosophila, allow dynamic chromosome interactions to be probed and quantitated. Our results suggest a very dynamic but highly determined and organized nucleus. Using these approaches, we can now study specific mechanisms leading to homologue chromosome pairing and position-effect variegation (Dernburg et al., 1996).

GROWTH OF POLLEN GRAIN NUCLEI OF TRADESCANTIA PALUDOSA

1976 ◽  
Vol 18 (2) ◽  
pp. 385-393 ◽  
Author(s):  
R. L. White ◽  
D. Davidson
Keyword(s):  
Normal Distribution ◽  
Root Meristem ◽  
Pollen Grain ◽  
Nuclear Volume ◽  
Interphase Nuclei ◽  
Rate Of Increase ◽  
Log Normal ◽  
Straight Lines ◽  
Log Normal Distribution ◽  
Tradescantia Paludosa

Pollen grain nuclei of Tradescantia paludosa Anderson and Woodson had a mean volume of 122 μm3 in early G1 and 1,415 μm3 in late G2. The distribution of nuclear volumes was not linear normal; however, it closely approximated a log normal distribution and probit plots yielded straight lines for the central 85-90% of the values. Most nuclei were spherical or nearly-spherical in early G1 but their increase in volume was accompanied by a change to an ovaloid or elongate shape. Interphase in the pollen grain lasted about five days at 25 °C. In the first 3.5 days the rate of increase in mean nuclear volume was about 87 μm3 per day. In the last 1.5 days of pollen grain interphase, nuclei increased at a mean rate of 658 μm3 per day; nuclear growth was relatively slow in G1 and rapid in G2. The largest nuclei tended to divide first; the result was that as the proportion of nuclei that have divided increased, mean nuclear volume decreased from 1415 μm3 to 680 μm3. Nuclear volumes were also determined for diploid nuclei of root meristem and sporogenous cells; their mean volumes were smaller, 1,355 μm3 and 1,018 μm3, than that of the G2 haploid nuclei, 1,415 μm3.

scholarly journals Vertebrate CTF18 and DDX11 essential function in cohesion is bypassed by preventing WAPL-mediated cohesin release

2021 ◽  
Vol 35 (19-20) ◽  
pp. 1368-1382
Author(s):  
Ryotaro Kawasumi ◽  
Takuya Abe ◽  
Ivan Psakhye ◽  
Keiji Miyata ◽  
Kouji Hirota ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Cellular Proliferation ◽  
Chromosome Structure ◽  
Sister Chromatid Cohesion ◽  
Anaphase Bridges ◽  
Chromatid Cohesion ◽  
Essential Function ◽  
Dt40 Cells

The alternative PCNA loader containing CTF18-DCC1-CTF8 facilitates sister chromatid cohesion (SCC) by poorly defined mechanisms. Here we found that in DT40 cells, CTF18 acts complementarily with the Warsaw breakage syndrome DDX11 helicase in mediating SCC and proliferation. We uncover that the lethality and cohesion defects of ctf18 ddx11 mutants are associated with reduced levels of chromatin-bound cohesin and rescued by depletion of WAPL, a cohesin-removal factor. On the contrary, high levels of ESCO1/2 acetyltransferases that acetylate cohesin to establish SCC do not rescue ctf18 ddx11 phenotypes. Notably, the tight proximity of sister centromeres and increased anaphase bridges characteristic of WAPL-depleted cells are abrogated by loss of both CTF18 and DDX11. The results reveal that vertebrate CTF18 and DDX11 collaborate to provide sufficient amounts of chromatin-loaded cohesin available for SCC generation in the presence of WAPL-mediated cohesin-unloading activity. This process modulates chromosome structure and is essential for cellular proliferation in vertebrates.

Some Biological Applications of High Voltage Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 298-299
Author(s):  
Hans Ris
Keyword(s):  
High Voltage ◽  
Chromosome Structure ◽  
Nerve Fibers ◽  
Good Resolution ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
University Of Wisconsin ◽  
High Voltage Electron ◽  
One Year ◽  
The University

The High Voltage Electron Microscope Laboratory at the University of Wisconsin has been in operation a little over one year. I would like to give a progress report about our experience with this new technique. The achievement of good resolution with thick specimens has been mainly exploited so far. A cold stage which will allow us to look at frozen specimens and a hydration stage are now being installed in our microscope. This will soon make it possible to study undehydrated specimens, a particularly exciting application of the high voltage microscope.Some of the problems studied at the Madison facility are: Structure of kinetoplast and flagella in trypanosomes (J. Paulin, U. of Georgia); growth cones of nerve fibers (R. Hannah, U. of Georgia Medical School); spiny dendrites in cerebellum of mouse (Scott and Guillery, Anatomy, U. of Wis.); spindle of baker's yeast (Joan Peterson, Madison) spindle of Haemanthus (A. Bajer, U. of Oregon, Eugene) chromosome structure (Hans Ris, U. of Wisconsin, Madison). Dr. Paulin and Dr. Hanna are reporting their work separately at this meeting and I shall therefore not discuss it here.

Effect of mesh on CFD aerodynamic performances of a container ship

2020 ◽  
Vol 20 (3) ◽  
pp. 343-353
Author(s):  
Ngo Van He ◽  
Le Thi Thai
Keyword(s):  
Water Surface ◽  
Reference Model ◽  
Full Scale ◽  
Scale Model ◽  
Container Ship ◽  
Ansys Fluent ◽  
Remarkable Effect ◽  
Aerodynamic Performances ◽  
Mesh Convergence

In this paper, a commercial CFD code, ANSYS-Fluent has been used to investigate the effect of mesh number generated in the computed domain on the CFD aerodynamic performances of a container ship. A full-scale model of the 1200TEU container ship has been chosen as a reference model in the computation. Five different mesh numbers for the same dimension domain have been used and the CFD aerodynamic performances of the above water surface hull of the ship have been shown. The obtained CFD results show a remarkable effect of mesh number on aerodynamic performances of the ship and the mesh convergence has been found. The study is an evidence to prove that the mesh number has affected the CFD results in general and the accuracy of the CFD aerodynamic performances in particular.

Morphological analysis of selective destruction of pancreatic beta-cells by cytotoxic T lymphocytes in NOD mice

Diabetes ◽  
1991 ◽  
Vol 40 (9) ◽  
pp. 1210-1217 ◽  
Author(s):  
M. Hayakawa ◽  
K. Yokono ◽  
M. Nagata ◽  
N. Hatamori ◽  
W. Ogawa ◽  
...  
Keyword(s):  
T Lymphocytes ◽  
Beta Cells ◽  
Cytotoxic T Lymphocytes ◽  
Pancreatic Beta Cells ◽  
Morphological Analysis ◽  
Nod Mice ◽  
Selective Destruction

Effect of log loading on the performance of wood room

2014 ◽  
Vol 29 (2) ◽  
pp. 201-210
Author(s):  
Ari Isokangas ◽  
Kari Ala-Kaila ◽  
Markku Ohenoja ◽  
Aki Sorsa ◽  
Kauko Leiviskä
Keyword(s):  
Product Quality ◽  
Material Properties ◽  
Raw Material ◽  
Performance Criteria ◽  
Processing Unit ◽  
Level Control ◽  
Paper Mills ◽  
Remarkable Effect ◽  
Loading Process ◽  
Small Wood

Abstract The purpose of this paper is to analyse the log loading process of wood room, which is typically the first processing unit in pulp and paper mills. The aim is to improve the log loading process to obtain production with a constant log flow of well de-iced logs to the debarking drum. This way it is possible to reduce costs and enhance product quality. The research was carried out utilising a log loading simulator. The parameters of the simulation model were selected on the basis of process observations on a mill. The results indicate that it is essential to adjust the process and equipment parameters, raw material properties and truck loader operation together in order to reach the target capacity with minimum costs. Especially the speed of the infeed conveyor affects all performance criteria and should be selected carefully. In addition, wood yard logistics and raw material properties have a remarkable effect on the wood room performance. The results can be utilised in mills to allow the upper level control perform in a planned way so that small wood loss and good product quality can be obtained.

Sign in / Sign up

Export Citation Format

Share Document