Thinopyrum distichum chromosome morphology and C-band distribution

1994 ◽  
Vol 88 (8) ◽  
pp. 949-955 ◽  
Author(s):  
G. M. Littlejohn ◽  
R. de V. Pienaar
Keyword(s):  
Chromosome Morphology

On an Application of the Metallurgical Stage to Chromosome Morphology

1967 ◽  
Vol 25 ◽  
pp. 28-29
Author(s):  
Godfrey C. Hoskins
Keyword(s):  
Human Chromosome ◽  
Electron Micrographs ◽  
Chromosome Morphology ◽  
Electron Optics ◽  
Electron Micrograph ◽  
Photographic Evidence ◽  
Sophisticated Equipment ◽  
Periodic Arrangement

The first serious electron microscooic studies of chromosomes accompanied by pictures were by I. Elvers in 1941 and 1943. His prodigious study, from the manufacture of micronets to the development of procedures for interpreting electron micrographs has gone all but unnoticed. The application of todays sophisticated equipment confirms many of the findings he gleaned from interpretation of images distorted by the electron optics of that time. In his figure 18 he notes periodic arrangement of pepsin sensitive “prickles” now called secondary fibers. In his figure 66 precise regularity of arrangement of these fibers can be seen. In his figure 22 he reproduces Siegbahn's first stereoscopic electron micrograph of chromosomes.The two stereoscopic pairs of electron micrographs of a human chromosome presented here were taken with a metallurgical stage on a Phillips EM200. These views are interpreted as providing photographic evidence that primary fibers (1°F) about 1,200Å thick are surrounded by secondary fibers (2°F) arranged in regular intervals of about 2,800Å in this metanhase human chromosome. At the telomere the primary fibers bend back on themselves and entwine through the center of each of each chromatid. The secondary fibers are seen to continue to surround primary fibers at telomeres. Thus at telomeres, secondary fibers present a surface not unlike that of the side of the chromosome, and no more susceptible to the addition of broken elements from other chromosomes.

scholarly journals Impaired Expression of Cytoplasmic Actins Leads to Chromosomal Instability of MDA-MB-231 Basal-Like Mammary Gland Cancer Cell Line

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2151
Author(s):  
Vera Dugina ◽  
Galina Shagieva ◽  
Mariya Novikova ◽  
Svetlana Lavrushkina ◽  
Olga Sokova ◽  
...  
Keyword(s):  
Cell Line ◽  
Chromosomal Instability ◽  
Cell Transformation ◽  
Cancer Cell Line ◽  
Neoplastic Cell ◽  
Chromosome Morphology ◽  
Human Carcinoma ◽  
Actin Isoforms ◽  
Cytoplasmic Actin ◽  
Neoplastic Cell Transformation

We have shown previously that two cytoplasmic actin isoforms play different roles in neoplastic cell transformation. Namely, β-cytoplasmic actin acts as a tumor suppressor, whereas γ-cytoplasmic actin enhances malignant features of tumor cells. The distinct participation of each cytoplasmic actin in the cell cycle driving was also observed. The goal of this study was to describe the diverse roles of cytoplasmic actins in the progression of chromosomal instability of MDA-MB-231 basal-like human carcinoma cell line. We performed traditional methods of chromosome visualization, as well as 3D-IF microscopy and western blotting for CENP-A detection/quantification, to investigate chromosome morphology. Downregulation of cytoplasmic actin isoforms alters the phenotype and karyotype of MDA-MB-231 breast cancer cells. Moreover, β-actin depletion leads to the progression of chromosomal instability with endoreduplication and aneuploidy increase. On the contrary, γ-actin downregulation results not only in reduced percentage of mitotic carcinoma cells, but leads to chromosome stability, reduced polyploidy, and aneuploidy.

scholarly journals Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 4
Author(s):  
Rafael Kretschmer ◽  
Ricardo José Gunski ◽  
Analía del Valle Garnero ◽  
Thales Renato Ochotorena de Freitas ◽  
Gustavo Akira Toma ◽  
...  
Keyword(s):  
Robertsonian Translocation ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Rare Event ◽  
Chromosome Morphology ◽  
Z Chromosome ◽  
Molecular Cytogenetic ◽  
Intrachromosomal Rearrangements ◽  
Genomic Reorganization

Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (Crotophaga ani). Our results demonstrate extensive chromosome reorganization in C. ani, with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.

Linear and Spatial Organization of Polytene Chromosomes of the African Malaria Mosquito Anopheles funestus

Genetics ◽  
2001 ◽  
Vol 159 (1) ◽  
pp. 211-218
Author(s):  
Igor V Sharakhov ◽  
Maria V Sharakhova ◽  
Charles M Mbogo ◽  
Lizette L Koekemoer ◽  
Guiyun Yan
Keyword(s):  
Spatial Organization ◽  
Polytene Chromosomes ◽  
Genetic Research ◽  
Anopheles Funestus ◽  
Chromosome Morphology ◽  
Pericentromeric Heterochromatin ◽  
Malaria Vectors ◽  
Malaria Mosquito ◽  
Cytogenetic Map ◽  
Important Species

Abstract Anopheles funestus Giles is one of the major malaria vectors in Africa, but little is known about its genetics. Lack of a cytogenetic map characterized by regions has hindered the progress of genetic research with this important species. This study developed a cytogenetic map of An. funestus using ovarian nurse cell polytene chromosomes. We demonstrate an important application with the cytogenetic map for characterizing various chromosomal inversions for specimens collected from coastal Kenya. The linear and spatial organization of An. funestus polytene chromosomes was compared with the best-studied malaria mosquito, An. gambiae Giles. Comparisons of chromosome morphology between the two species have revealed that the most extensive chromosomal rearrangement occurs in pericentromeric heterochromatin of autosomes. Differences in pericentromeric heterochromatin types correlate with nuclear organization differences between An. funestus and An. gambiae. Attachments of chromosomes to the nuclear envelope strongly depend on the presence of diffusive β-heterochromatin. Thus, An. funestus and An. gambiae exhibit species-specific characteristics in chromosome-linear and -spatial organizations.

Repetitive arrays containing a housekeeping gene have altered polytene chromosome morphology in Drosophila

Chromosoma ◽  
1998 ◽  
Vol 107 (2) ◽  
pp. 96-104 ◽  
Author(s):  
Denise V. Clark ◽  
Joy F. Sabl ◽  
Steven Henikoff
Keyword(s):  
Polytene Chromosome ◽  
Housekeeping Gene ◽  
Chromosome Morphology

scholarly journals Analysis of Chromosome Morphology and Possible Means of Speciation in Jasminum

CYTOLOGIA ◽  
1958 ◽  
Vol 23 (2) ◽  
pp. 172-185 ◽  
Author(s):  
Arun Kumar Sharma ◽  
Archana Sharma
Keyword(s):  
Chromosome Morphology

The influence of fixation on the morphology of mitotic chromosomes

1986 ◽  
Vol 28 (4) ◽  
pp. 536-539 ◽  
Author(s):  
Axel J. J. Dietrich
Keyword(s):  
Acetic Acid ◽  
Chemical Composition ◽  
Strong Influence ◽  
Chromosome Structure ◽  
Human Lymphocytes ◽  
Chromosome Morphology ◽  
Mitotic Chromosomes ◽  
Specific Chemical ◽  
C Banding ◽  
Sister Chromatids

It is well known that there is a strong influence of fixation, i.e., acetic methanol versus formaldehyde, on the chromosome morphology at stages of the first meiotic division. In this study the influence of both these types of fixation on the morphology of mitotic chromosomes was examined in human lymphocytes. After methanol – acetic acid (3:1) fixation, the chromosomes show the "classical" condensed shape in which it is not always possible to recognize the two sister chromatids. These chromosomes are accessible to the conventional G-, R-, and C-banding techniques. After formaldehyde fixation at a relatively high pH, the chromosomes are thinner and longer (two to six times) when compared with chromosomes following methanol – acetic acid fixation. They show a scaffold-like morphology, sometimes with a halo of thin material around it. In all cases the two sister chromatids could be recognized. This chromosome structure could be easily stained with silver, Giemsa, 4,6-diamino-2-phenyl-indole (DAPI), and fluorescein isocyanate isomere 1 (FITC). The results obtained following these stainings gave no indication to any specific chemical composition of a probable central scaffold. The scaffold-like structures were not accessible to G-, R-, or C-banding techniques. The only effect observed following these banding techniques was the disappearance of the halo of thin material around the central scaffold-like structure.Key words: chromosome structure, fixation influence, human lymphocytes.

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