Meiotic configurations in the oospore of Phytophthora capsici

1974 ◽  
Vol 52 (10) ◽  
pp. 2141-2143 ◽  
Author(s):  
L. W. Stephenson ◽  
D. C. Erwin ◽  
J. V. Leary
Keyword(s):  
Phytophthora Capsici ◽  
Nuclear Size ◽  
Chromosome Size ◽  
Haploid Number ◽  
Whole Mounts ◽  
Metaphase I

Photomicrographs of chromosomal configurations in nuclei of squashed whole mounts of mature oospores (cultures 32 days old) of Phytophthora capsici stained with iron hematoxylin were interpreted to indicate that meiosis occurred in the oospore. Chromosomes in dividing oospore nuclei were observed in synapsis, diakinesis, metaphase I, and metaphase II. Comparison of polar metaphase I and metaphase II plates revealed a reduction in chromosome size and number and nuclear size. The haploid number of chromosomes was interpreted to be 6.

Gametangial meiosis in Phytophthora capsici

1976 ◽  
Vol 54 (13) ◽  
pp. 1535-1545 ◽  
Author(s):  
E. Sansome
Keyword(s):  
Chromosome Number ◽  
Phytophthora Capsici ◽  
Nuclear Size ◽  
Chromosome Size ◽  
Chromosome Counts ◽  
Haploid Chromosome Number ◽  
Zygote Nucleus ◽  
Gametangial Meiosis

The report of Stephenson et al. that the nuclear divisions in the gametangia of Phytophthora capsici are mitotic, resembling the divisions in the vegetative hyphae, was not confirmed. Pachytene, diplotene, and diakinesis stages were observed in the oogonia. Metaphase and anaphase were followed by a second division without any increase in nuclear and chromosome size between the two divisions. The haploid chromosome number is nine and an association of four chromosomes is present in one or both parents.The association of four chromosomes observed at diakinesis and metaphase is evidence that pairing of homologous parts occurs during the first division and is thus proof that the gametangial divisions are meiotic.There was no evidence of a prolonged prophase in the first division of the zygote nucleus and an eight-nucleate oospore showed no evidence of reduction in nuclear size or nuclear elimination such as would be required to account for the homokaryotic condition of single-oospore cultures on the hypothesis of zygotic meiosis.The problems involved in obtaining reliable chromosome counts from somatic nuclei are discussed.

Chromosome size, morphology, and gene density determine bivalent positioning in metaphase I human spermatocytes

2014 ◽  
Vol 101 (3) ◽  
pp. 818-824.e3 ◽  
Author(s):  
Laia Vergés ◽  
Joan Blanco ◽  
Oliver Valero ◽  
Francesca Vidal ◽  
Zaida Sarrate
Keyword(s):  
Gene Density ◽  
Chromosome Size ◽  
Metaphase I

scholarly journals Intranuclear DNA density affects chromosome condensation in metazoans

2013 ◽  
Vol 24 (15) ◽  
pp. 2442-2453 ◽  
Author(s):  
Yuki Hara ◽  
Mari Iwabuchi ◽  
Keita Ohsumi ◽  
Akatsuki Kimura
Keyword(s):  
Chromosome Condensation ◽  
Nuclear Size ◽  
Nuclear Space ◽  
Chromosome Size ◽  
Condensed Chromosome ◽  
Free System ◽  
A Cell ◽  
Spatial Parameters ◽  
Degree Of Condensation ◽  
Dna Density

Chromosome condensation is critical for accurate inheritance of genetic information. The degree of condensation, which is reflected in the size of the condensed chromosomes during mitosis, is not constant. It is differentially regulated in embryonic and somatic cells. In addition to the developmentally programmed regulation of chromosome condensation, there may be adaptive regulation based on spatial parameters such as genomic length or cell size. We propose that chromosome condensation is affected by a spatial parameter called the chromosome amount per nuclear space, or “intranuclear DNA density.” Using Caenorhabditis elegans embryos, we show that condensed chromosome sizes vary during early embryogenesis. Of importance, changing DNA content to haploid or polyploid changes the condensed chromosome size, even at the same developmental stage. Condensed chromosome size correlates with interphase nuclear size. Finally, a reduction in nuclear size in a cell-free system from Xenopus laevis eggs resulted in reduced condensed chromosome sizes. These data support the hypothesis that intranuclear DNA density regulates chromosome condensation. This suggests an adaptive mode of chromosome condensation regulation in metazoans.

scholarly journals Morphology and Meiotic Behavior of Three Dendrobium Amphidiploids and Their Diploid Counterparts

HortScience ◽  
1993 ◽  
Vol 28 (9) ◽  
pp. 935-937 ◽  
Author(s):  
James McConnell ◽  
H. Kamemoto
Keyword(s):  
Small Chromosome ◽  
Chromosome Size ◽  
Meiotic Behavior ◽  
Preferential Pairing ◽  
Bivalent Formation ◽  
Metaphase I

Floral characteristics, meiotic behavior, and sporad formation were compared in three Dendrobium tetraploids (amphidiploids) and their diploid counterparts. Amphidiploid flowers were larger than those of diploids. Diploid meiotic behavior varied; mean configurations at Metaphase I ranged from 14.3 bivalents and 9.4 univalents to 18.9 bivalents and 0.2 univalents. In amphidiploids, nearly all cells had 38 bivalents. Sporad formation also varied; diploids had 36% to 70% tetrads and amphidiploids had 97% to 100% tetrads. Preferential pairing and small chromosome size may promote bivalent formation in amphidiploids.

Meiosis in allopolyploid Crepis capillaris. II. Autotetraploids

Genome ◽  
1994 ◽  
Vol 37 (3) ◽  
pp. 497-505 ◽  
Author(s):  
G. H. Jones ◽  
J. E. Vincent
Keyword(s):  
Meiotic Chromosome ◽  
Positional Distribution ◽  
Chromosome Size ◽  
High Frequencies ◽  
Crepis Capillaris ◽  
Prophase I ◽  
Direct Observations ◽  
Surface Spread ◽  
Pairing Initiation ◽  
Metaphase I

Meiotic chromosome pairing of autotetraploid Crepis capillaris was analysed by electron microscopy of surface-spread prophase I nuclei and compared with light microscopic observations of metaphase I chromosome configurations. Prophase I quadrivalent frequencies are high in all three tetrasomes. (A, D, and C) and partially dependent on chromosome size. At metaphase I quadrivalent frequencies are much lower and strongly dependent on chromosome size. There is no evidence for multivalent elimination during prophase I in this system, and the reduction in multivalent frequency at metaphase I can be explained by an insufficiency of appropriately placed chiasmata. The high frequencies of prophase I quadrivalents far exceed the two-thirds expected on a simple model with two terminal independent pairing initiation sites per tetrasome, suggesting that multiple pairing initiation occurs. Direct observations reveal relatively high frequencies of pairing partner switches (PPSs) at prophase I, which confirms this suggestion. The numbers of PPSs per tetrasome show a good fit to the Poisson distribution, and their positional distribution along chromosomes is random and nonlocalized. These observations favour a model of pairing initiation based on a large number of evenly distributed autonomous pairing sites each with a uniform and low probability of generating a PPS.Key words: autotetraploid, meiosis, Crepis capillaris, multivalent, pairing partner switch.

Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

1977 ◽  
Vol 35 ◽  
pp. 562-563
Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Serial Sections ◽  
Thin Sections ◽  
3 Dimensional ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Dimensional Reconstruction ◽  
Stereo Imagery ◽  
Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

Regulation of nuclear size in mammalian embryos

2014 ◽  
Author(s):  
Elina Tsichlaki ◽  
Greg Fitzharris
Keyword(s):  
Nuclear Size ◽  
Mammalian Embryos

Chromosome size-dependent control of meiotic recombination

Science ◽  
1992 ◽  
Vol 256 (5054) ◽  
pp. 228-232 ◽  
Author(s):  
D. Kaback ◽  
V Guacci ◽  
D Barber ◽  
J. Mahon
Keyword(s):  
Meiotic Recombination ◽  
Chromosome Size ◽  
Size Dependent

scholarly journals Facile Synthesis of Carboxymethyl Cellulose Coated Core/Shell SiO2@Cu Nanoparticles and Their Antifungal Activity against Phytophthora capsici

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 888
Author(s):  
Nguyen Thi Thanh Hai ◽  
Nguyen Duc Cuong ◽  
Nguyen Tran Quyen ◽  
Nguyen Quoc Hien ◽  
Tran Thi Dieu Hien ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Carboxymethyl Cellulose ◽  
Chemical Reduction ◽  
Low Cost ◽  
Phytophthora Capsici ◽  
Reduction Process ◽  
Spherical Shape ◽  
Core Shell ◽  
Cu Nanoparticles ◽  
Average Size

Cu nanoparticles are a potential material for creating novel alternative antimicrobial products due to their unique antibacterial/antifungal properties, stability, dispersion, low cost and abundance as well as being economical and ecofriendly. In this work, carboxymethyl cellulose coated core/shell SiO2@Cu nanoparticles (NPs) were synthesized by a simple and effective chemical reduction process. The initial SiO2 NPs, which were prepared from rice husk ash, were coated by a copper ultrathin film using hydrazine and carboxymethyl cellulose (CMC) as reducing agent and stable agent, respectively. The core/shell SiO2@Cu nanoparticles with an average size of ~19 nm were surrounded by CMC. The results indicated that the SiO2@Cu@CMC suspension was a homogenous morphology with a spherical shape, regular dispersion and good stability. Furthermore, the multicomponent SiO2@Cu@CMC NPs showed good antifungal activity against Phytophthora capsici (P. capsici). The novel Cu NPs-based multicomponent suspension is a key compound in the development of new fungicides for the control of the Phytophthora disease.

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