Metaphase position of an interchange quadrivalent of Allium triquetrum

1988 ◽  
Vol 90 (3) ◽  
pp. 493-499
Author(s):  
GEOFFREY K. RICKARDS ◽  
WENDY A. BAKER
Keyword(s):  
Linear Array ◽  
Metaphase Plate ◽  
Real Data ◽  
Slide Preparation ◽  
Metaphase I

The position of an interchange quadrivalent at metaphase I of Allium triquetrum was modelled so as to simulate the original placement of the quadrivalent in the spindle and the preparation of linear spreads through squashing. In this way an expected distribution for the quadrivalent in linear spreads was generated. The procedure used polar views of metaphase I to which the quadrivalent was assigned pairs of positions normally occupied by bivalents. The positions of the bivalents and assigned quadrivalent were then into a linear array and analysed as ‘real’ data. Comparisons with observed distributions showed that a general bias in favour of marginal placement of the quadrivalent in the linear array is expected; and also showed that the quadrivalent is positioned non-randomly in the metaphase plate prior to slide preparation.

THE ULTRASTRUCTURE OF KINETOCHORES OF UNPAIRED CHROMOSOMES IN A WHEAT HYBRID

1973 ◽  
Vol 15 (4) ◽  
pp. 801-806 ◽  
Author(s):  
E. B. Wagenaar ◽  
D. F. Bray
Keyword(s):  
Sister Chromatid ◽  
Metaphase Plate ◽  
Polar Regions ◽  
Equatorial Plate ◽  
Univalent Chromosome ◽  
Wheat Hybrid ◽  
Opposite Pole ◽  
Kinetochore Region ◽  
Metaphase I

The kinetochore region of unpaired chromosomes (univalents) consists of two kinetochores, each belonging to a sister chromatid, that are located adjacent to one another on the surface of the univalent chromosome. This condition results in a movement by the univalent towards one of the polar regions at the onset of metaphase I. Once arrived in this region, one of the sister kinetochores obtains attachments of microtubules from the opposite pole. This results in a gradual return of the univalent to the equatorial plate, where it reaches an equilibrium. The sister kinetochores remain adjacent during the movement, but once arrived at the metaphase plate they develop a typical mitotic appearance, in which the sister kinetochores have opposite positions on the chromosomes.

scholarly journals Two types of highly ordered micro- and macrochromosome arrangement in metaphase plates of butterflies (Lepidoptera)

2019 ◽  
Vol 13 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Vladimir A. Lukhtanov
Keyword(s):  
Metaphase Plate ◽  
Meiotic Metaphase ◽  
Chromosome Organization ◽  
Cell Divisions ◽  
Size Groups ◽  
Metaphase I

In karyotype of many organisms, chromosomes form two distinct size groups: macrochromosomes and microchromosomes. During cell divisions, the position of the macro- and microchromosomes is often ordered within metaphase plate. In many reptiles, amphibians, birds, insects of the orthopteran family Tettigoniidae and in some plants, a so called “reptilian” type organization is found, with microchromosomes situated in the center of metaphase plate and with macrochromosomes situated at the periphery. An opposite, “lepidopteran” type is known in butterflies and moths (i.e. in the order Lepidoptera) and is characterized by macrochromosomes situated in the center and by microchromosomes situated at the periphery. The anomalous arrangement found in Lepidoptera was previously explained by holocentric organization of their chromosomes. Here I analyse the structure of meiotic metaphase I plates in ithomiine butterfly, Forbestraolivencia (H. Bates, 1862) (Nymphalidae, Danainae, Ithomiini) which has a clear “reptilian” organization, contrary to previous observations in Lepidoptera. In this species large bivalents (i.e. macrochromosomes) form a regular peripheral circle, whereas the minute bivalents (i.e. microchromosomes) occupy the center of this circle. The reasons and possible mechanisms resulting in two drastically different spatial chromosome organization in butterflies are discussed.

scholarly journals The ultrastructure and timing of events in the nuclear cycle of the fungus Entomophaga aulicae

1988 ◽  
Vol 90 (3) ◽  
pp. 501-516
Author(s):  
FAYE MURRIN ◽  
WILLIAM NEWCOMB ◽  
I. BRENT HEATH
Keyword(s):  
Nuclear Envelope ◽  
Linear Array ◽  
Nuclear Division ◽  
Metaphase Plate ◽  
Serial Sections ◽  
Free Zone ◽  
Nuclear Cycle ◽  
Full Complement ◽  
Spindle Microtubules ◽  
Spindle Elongation

The ultrastructure of the mitotic nuclear division cycle of the fungus Entomophaga aulicae was studied from serial sections of hyphal tips and protoplasts. The extranuclear bar-shaped nucleus- associated organelle (NAO) remained associated with the persistent nuclear envelope throughout. Prior to spindle formation, a patch of intranuclear NAO-associated chromatin detached from the nuclear envelope to yield a chromatin free zone containing fine filaments and a linear array of presumptive kinetochores. Early metaphase spindles less than 1μm in length were characterized by a ‘fused’ metaphase plate consisting of kinetochore-associated chromatin and a full complement of at least 15 kinetochore microtubules per half-spindle, while most of the chromatin was remote from the intranuclear spindle. Analysis of the distribution of antiparallel spindle microtubules indicated that polar separation and concomitant spindle elongation through metaphase were not accompanied by intermicrotubule sliding. Anaphase exhibited extensive decondensation of the large patches of condensed chromatin characteristic of all other stages. In a logarithmically growing protoplast population all nuclei contained spindle microtubules, with metaphase occupying approximately 66% of the nuclear cycle time. The calculated genome size of 4.3 pg, and average DNA content per chromosome of 0.3 pg, are extremely high for fungi.

scholarly journals Chromosome stickiness during meiotic behavior analysis of Passiflora serrato-digitata L. (PassifloraCEAE)

2011 ◽  
Vol 41 (6) ◽  
pp. 1018-1023 ◽  
Author(s):  
Paulo Roberto Peres Kiihl ◽  
Andréia Rodrigues Alonso Pereira ◽  
Sara Mataroli de Godoy ◽  
Neusa Maria Colauto Stenzel ◽  
Claudicéia Risso-Pascotto
Keyword(s):  
Behavior Analysis ◽  
Metaphase Plate ◽  
Meiotic Behavior ◽  
American Continent ◽  
Segregation Process ◽  
Ethanol Acetic Acid ◽  
Experimental Base ◽  
Chromosome Stickiness ◽  
First Time ◽  
Metaphase I

Almost 90% of species of the genus Passiflora are native to the American continent, with high commercial value due to the fact that some species are used for human food while others have ornamental and medical qualities. Passiflora serrato-digitata is one of the species that integrates the Paraná Agronomic Institute germoplasm bank at its experimental base in Londrina, PR, Brazil. Collected flower buds were fixed in ethanol/acetic acid (3:1 v/v) for 24h, transferred to 70% alcohol and stored under refrigeration. Slides were prepared by the squashing technique and stained with 1.0% propionic carmine; they were analyzed under an optic microscope. Irregularities in the chromosome segregation process of P. serrato-digitata have been verified by meiotic behavior analysis. These comprised precocious migration to poles in metaphase I and II, non-oriented chromosomes in metaphase plate in metaphase I and II, laggard chromosomes in anaphase I and II towards the formation of micronucleus in telophase I and II, and microspores in tetrads. Chromosome stickiness was another irregularity reported in the Passiflora genus for the first time. These irregularities which also contributed to the formation of monads, dyads and triads, resulted in normal imbalanced 2n and 4n microspores. According to the observed Meiotic Index of 71.83%, this species is not meiotically stable.

Retrieval of amplitude and attenuation from ambient seismic noise: synthetic data and practical considerations

2020 ◽  
Vol 222 (1) ◽  
pp. 544-559
Author(s):  
Lianqing Zhou ◽  
Xiaodong Song ◽  
Richard L Weaver
Keyword(s):  
Numerical Simulation ◽  
Seismic Data ◽  
Seismic Noise ◽  
Ambient Noise ◽  
Linear Array ◽  
Noise Source ◽  
Synthetic Data ◽  
Real Data ◽  
Noise Correlation ◽  
Theoretical Derivation

SUMMARY Ambient noise correlation has been used extensively to retrieve traveltimes of surface waves. However, studies of retrieving amplitude information and attenuation from ambient noise are limited. In this study, we develop methods and strategies to extract Rayleigh wave amplitude and attenuation from ambient noise correlation, based on theoretical derivation, numerical simulation, and practical considerations of real seismic data. The synthetic data included a numerical simulation of a highly anisotropic noise source and Earth-like temporally varying strength. Results from synthetic data validate that amplitudes and attenuations can indeed be extracted from noise correlations for a linear array. A temporal flattening procedure is effective in speeding up convergence while preserving relative amplitudes. The traditional one-bit normalization and other types of temporal normalization that are applied to each individual station separately are problematic in recovering attenuation and should be avoided. In this study, we propose an ‘asynchronous’ temporal flattening procedure for real data that does not require all stations to have data at the same time. Furthermore, we present the detailed procedure for amplitude retrieval from ambient noise. Tests on real data suggest attenuations extracted from our noise-based methods are comparable with those from earthquakes. Our study shows an exciting promise of retrieving amplitude and attenuation information from ambient noise correlations and suggests practical considerations for applications to real data.

34 PRE-IMPLANTATION DEVELOPMENT OF HORSE SOMATIC CELL NUCLEAR TRANSFER EMBRYOS ORIGINATED FROM METAPHASE I OOCYTES

2013 ◽  
Vol 25 (1) ◽  
pp. 165
Author(s):  
I. Lagutina ◽  
S. Colleoni ◽  
G. Lazzari ◽  
C. Galli
Keyword(s):  
Growth Factor ◽  
Nuclear Transfer ◽  
Polar Body ◽  
Metaphase Plate ◽  
Developmental Competence ◽  
Blastocyst Formation ◽  
Chi Square ◽  
Serum Replacement ◽  
Chi Square Test ◽  
Metaphase I

Because of the limited availability of horse oocytes and their wide maturation window that leads to the existence of a subpopulation of oocytes with significantly longer maturation period, horse cloning would benefit from the possibility of also using metaphase I oocytes (Choi et al. 2009 Cloning Stem Cells). The scope of this work was to compare the developmental ability of cloned horse embryos constructed using oocytes in metaphase I (MI) and II (MII). Oocytes of slaughtered mares were matured for 27 h in DMEM/F12 with 10% FCS, 1 µL mL–1 of insulin-transferrin-selenium (ITS), 1 mM sodium pyruvate, 50 ng mL–1 of long-epidermal growth factor, 100 ng mL–1 of long-insulin-like growth factor-I, and 0.1 IU mL–1 each of FSH and LH, denuded of cumulus and enucleated using a zona-free method (Lagutina et al. 2005 Reproduction). Oocytes with a visible polar body were classified as MII and those with no polar body as potential MI. During enucleation, oocytes having a metaphase plate only were confirmed as MI; oocytes in anaphase and telophase were classified as MII. Adult skin fibroblasts of passages 2 to 10 were cultured in TCM 199/DMEM with 10% FCS and serum starved for 1 to 2 days before NT. Nuclear-transfer embryos were constructed after washing of zona-free oocytes in 400 µg mL–1 of phytohemagglutinin P and attachment of each to a single cell in HEPES-SOF by fusion with 2 direct-current (DC) pulses of 1.2 kV cm–1 applied for 30 µs in fusion medium. One hour after fusion, embryos were activated by 5 µM ionomycin for 4 min, followed by culture in 5 µg mL–1 of cycloheximide and 1 mM DMAP in SOFaa for 3 h. Embryos were cultured in SOFaa in 5% CO2 and 5% O2 at 38.5°C. Half of the medium was renewed on Day 3 and replaced on Day 5 with DMEM/F12 with 5% FCS and 5% serum replacement. Cleavage was assessed 48 h after activation and the rate of blastocyst formation was recorded at Day 8. The data were compared by chi-square test. The development ability of MI embryos assessed by cleavage and blastocyst formation was significantly lower than of MII embryos (Table 1). The obtained MI blastocysts were smaller than their MII counterparts. These data demonstrate that MI oocytes account for 20% of the total oocytes after 27 h of maturation, have a lower developmental competence to form blastocysts after NT, and the blastocysts obtained are of smaller size and likely less viable. Therefore, the use of MI oocytes can only marginally improve the outcome of horse cloning. Table 1.Embryo development after SCNT using oocytes in metaphase I or II

Phosphorylated proteins are involved in sister-chromatid arm cohesion during meiosis I

1999 ◽  
Vol 112 (17) ◽  
pp. 2957-2969 ◽  
Author(s):  
J.A. Suja ◽  
C. Antonio ◽  
A. Debec ◽  
J.S. Rufas
Keyword(s):  
Sister Chromatid ◽  
Chromosome Structure ◽  
Metaphase Plate ◽  
Mitotic Chromosomes ◽  
Phosphorylated Proteins ◽  
Sister Chromatids ◽  
Sequential Release ◽  
Sister Kinetochore ◽  
Meiosis I ◽  
Metaphase I

Sister-chromatid arm cohesion is lost during the metaphase I/anaphase I transition to allow homologue separation. To obtain needed information on this process we have analysed in grasshopper bivalents the sequential release of arm cohesion in relation to the behaviour of chromatid axes. Results show that sister axes are associated during early metaphase I but separate during late metaphase I leading to a concomitant change of chromosome structure that implies the loss of sister-kinetochore cohesion. Afterwards, homologues initiate their separation asynchronously depending on their size, and number and position of chiasmata. In all bivalents thin chromatin strands at the telomeres appeared as the last point of contact between sister chromatids. Additionally, we have analysed the participation of phosphoproteins recognised by the MPM-2 monoclonal antibody against mitotic phosphoproteins in arm cohesion in bivalents and two different kinds of univalents. Results show the absence of MPM-2 phosphoproteins at the interchromatid domain in mitotic chromosomes and meiotic univalents, but their presence in metaphase I bivalents. These phosphoproteins are lost at the onset of anaphase I. Taken together, these data have prompted us to propose a ‘working’ model for the release of arm cohesion during meiosis I. The model suggests that MPM-2 phosphoproteins may act as cohesive proteins associating sister axes. Their modification, once all bivalents are correctly aligned at the metaphase plate, would trigger a change of chromosome structure and the sequential release of sister-kinetochore, arm, and telomere cohesions.

scholarly journals Position and orientation in the metaphase equator of an interchange quadrivalent of Allium triquetrum

1984 ◽  
Vol 43 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Geoffrey K. Rickards
Keyword(s):  
Metaphase Plate ◽  
Pollen Mother Cells ◽  
Alternate Orientation ◽  
Interchange Heterozygote ◽  
Position And Orientation ◽  
Mother Cells ◽  
Metaphase I

SUMMARYThe position and orientation of an interchange quadrivalent in flattened, lateral views of metaphase I were studied in pollen-mother-cells of an interchange heterozygote of Allium triquetrum. The quadrivalent is most often located in marginal rather than central positions in the equator. Moreover, when positioned marginally the quadrivalent is more often than expected found in adjacent orientation, whilst when positioned centrally it is more often than expected found in alternate orientation. Consequently, the frequency of alternate (genetically balanced) orientation in the quadrivalent varies sharply according to whether data are obtained from more marginal or more central positions in the metaphase plate.

Umatilla Virus Association with Fibrils and Tubules in Cultured Cells

1980 ◽  
Vol 38 ◽  
pp. 476-477
Author(s):  
Neil M. Foster ◽  
Ruth D. Breckon
Keyword(s):  
Bluetongue Virus ◽  
Linear Array ◽  
Cultured Cells ◽  
Intimate Association ◽  
Infected Cells ◽  
Dark Staining ◽  
In Cells

Macrotubules have been described1 in cells infected with Umatilla virus (UMAV), an orbivirus for which bluetongue virus (BTV) is the protype. Macrotubules, often in linear array, were observed in the cytoplasm and in intimate association with viroplasms of infected cells. Macrotubules had outside and inside diameters of 20 and 15 nm and many had dark-staining centers with diameters similar to the interiors of the tubules. UMAV was 60 nm and the RNA core was 30 nm in diameter. This report describes the association of UMAV with macrotubules and two types of microtubules.

Detecting Random Responses in a Personality Scale Using IRT-Based Person-Fit Indices

2019 ◽  
Vol 35 (1) ◽  
pp. 126-136 ◽  
Author(s):  
Tour Liu ◽  
Tian Lan ◽  
Tao Xin
Keyword(s):  
Experimental System ◽  
Real Data ◽  
Fit Indices ◽  
Random Response ◽  
Person Fit ◽  
Index Method ◽  
Single Person ◽  
Person Fit Index ◽  
Random Responses ◽  
Response Behaviors

Abstract. Random response is a very common aberrant response behavior in personality tests and may negatively affect the reliability, validity, or other analytical aspects of psychological assessment. Typically, researchers use a single person-fit index to identify random responses. This study recommends a three-step person-fit analysis procedure. Unlike the typical single person-fit methods, the three-step procedure identifies both global misfit and local misfit individuals using different person-fit indices. This procedure was able to identify more local misfit individuals than single-index method, and a graphical method was used to visualize those particular items in which random response behaviors appear. This method may be useful to researchers in that it will provide them with more information about response behaviors, allowing better evaluation of scale administration and development of more plausible explanations. Real data were used in this study instead of simulation data. In order to create real random responses, an experimental test administration was designed. Four different random response samples were produced using this experimental system.

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