Chromosome form and behaviour in diploid and triploidAconitum

1933 ◽  
Vol 27 (2) ◽  
pp. 293-318 ◽  
Author(s):  
A. Afify
Keyword(s):  
Chromosome Form

THE STRUCTURE AND DEVELOPMENT OF THE CHROMOSOME SPIRALS IN MICROSPORES OF TRILLIUM

1942 ◽  
Vol 20c (4) ◽  
pp. 257-266 ◽  
Author(s):  
A. H. Sparrow
Keyword(s):  
Meiotic Prophase ◽  
Spiral Structure ◽  
Chromosome Form ◽  
Single Coil ◽  
Contraction Ratio

The structure and development of somatic spirals in microspore chromosomes of Trillium have been investigated. The chromonemata in each metaphase chromatid and each anaphase chromosome form a large-gyred, hollow spiral. This spiral develops gradually during prophase by an increase in gyre diameter and a decrease in gyre number and in chromatid length. Its development is associated with the elimination not the production of chromatid relational coiling. At later stages an irregular waviness or "minor" somatic spiral is visible along its "major" gyres in which reversals of direction can also be discerned. Where the spiral can be seen to be double-stranded it is plectonemic (as early as mid-prophase).The prophase to metaphase chromatid contraction ratio is not less than 6:1. Mean chromonema length increases from 650 ± 17.2 at metaphase to 977 ± 28.3 at anaphase. This latter length is approximately that estimated for early meiotic prophase. Chromosome volume also increases (about twofold) during the interval between metaphase and anaphase. Mean chromonema length and gyre number in microspore anaphase chromosomes are more than twice as great as those of meiotic anaphase chromosomes. Since the chromosomes at these stages are of approximately the same mean length the gyres of the somatic spiral are thus more tightly "packed".In Trillium, microspore anaphase chromosomes are considered to be of essentially the same spiral structure as meiotic second division chromosomes, i.e., a single coil (but not single-stranded), rather than two or more independently coiled chromatids. The process of reducing this plectonemic spiral into parallel, freely-separable chromatids begins in one prophase as a reduction in gyre number and continues as relational uncoiling in the next. Paradoxically, therefore, a spiralization cycle such as that described above can be interpreted as an uncoiling process in which successive cycles overlap in prophase.

scholarly journals Boundaries of loop domains (insulators): Determinants of chromosome form and function in multicellular eukaryotes

BioEssays ◽  
2017 ◽  
Vol 39 (3) ◽  
pp. 1600233 ◽  
Author(s):  
Darya Chetverina ◽  
Miki Fujioka ◽  
Maksim Erokhin ◽  
Pavel Georgiev ◽  
James B. Jaynes ◽  
...  
Keyword(s):  
Chromosome Form ◽  
Form And Function ◽  
And Function ◽  
Loop Domains

Sex Chromosome Translocations

2018 ◽  
Author(s):  
R. J McKinlay Gardner ◽  
David J Amor
Keyword(s):  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Transcriptional Silencing ◽  
The Other ◽  
X Chromosomes ◽  
Chromosome Form ◽  
Chromosome Translocations ◽  
Y Chromosomes ◽  
Autosomal Translocation

The sex chromosomes (gonosomes) are different, and sex chromosome translocations need to be considered separately from translocations between autosomes. A sex chromosome can engage in translocation with an autosome, with the other sex chromosome, or even with its homolog. The qualities of the sex chromosomes have unique implications in terms of the genetic functioning of gonosome-autosome translocations. This chapter acknowledges the specific peculiarities that the sex chromosomes imply: the X being subject to transcriptional silencing; and the very small Y gene complement being confined largely to sex-determining loci. It reviews translocations between sex chromosomes and autosomes; between X and Y chromosomes; and even the very rare circumstance of between X chromosomes and between Y chromosomes. The differences in assessing risk, according to chromosome form, in comparison with the autosomal translocation, are reviewed, and the biology behind these differences is discussed.

Chromosome form and function

Chromosomes ◽  
1996 ◽  
pp. 27-71 ◽  
Author(s):  
M. S. Clark ◽  
W. J. Wall
Keyword(s):  
Chromosome Form ◽  
Form And Function ◽  
And Function

Chromosome form and behaviour in tetraploidAconitum

1938 ◽  
Vol 36 (3) ◽  
pp. 373-394 ◽  
Author(s):  
A. Afify
Keyword(s):  
Chromosome Form

CGG repeats associated with fragile X chromosome form left-handed Z-DNA structure

Biopolymers ◽  
2010 ◽  
Vol 95 (3) ◽  
pp. 174-181 ◽  
Author(s):  
Daniel Renčiuk ◽  
Jaroslav Kypr ◽  
Michaela Vorlíčková
Keyword(s):  
X Chromosome ◽  
Fragile X ◽  
Dna Structure ◽  
Chromosome Form ◽  
Left Handed ◽  
Cgg Repeats ◽  
Z Dna

scholarly journals EXPANSION OF CYTOGENETICALLY MODIFIED FORM OF OPISTHORCHIS FELINEUS IN THE TOM RIVER BASIN

2016 ◽  
pp. 65-69
Author(s):  
Nikolai Ilyinskikh ◽  
Nikolai Ilyinskikh ◽  
Ekaterina Ilyinskikh ◽  
Ekaterina Ilyinskikh
Keyword(s):  
River Basin ◽  
Industrial Wastewater ◽  
Robertsonian Fusion ◽  
Experimental Conditions ◽  
Opisthorchis Felineus ◽  
Chromosome Form ◽  
Golden Hamsters ◽  
Siberian Chemical ◽  
Chromosome Karyotype

In 1993, karyotyping of Opisthorchis felineus sporocysts, isolated from aquatic mollusks Bithynia inflat a in the industrial wastewater of the Siberian Chemical Combine discovered cytogenetically modified 12-chromosome specimens. In 2012-2013, a repeated study of the spread of these mutant trematodes in the lower course of the river Tom was carried out. It was established that specimens with sporocysts of O. felineus having 2n=12 were found in 8 of 10 places of catching. The caught goldfish were used to isolate metacercariae to infest golden hamsters in the experimental conditions. After 5 months, the hamster livers were processed to extract marita specimens and the number of chromosomes in their ovaries and testes was cytogenetically determined. The results of analysis of the spread of O. felineus carried out by this method showed the presence of 12-chromosome form of the Opisthorchis marita in all places of fishing out in the lower course of the river Tom. Analysis of the 12-chromosome karyotype allows to conclude that this mutation was a result of Robertsonian fusion of chromosomes 3 and 6 of 14-chromosome form of karyotype.

Chromosome form and Number in the Larvacea

1973 ◽  
Vol 40 (3-4) ◽  
pp. 347-353 ◽  
Author(s):  
D. Colombera ◽  
R. Fenaux
Keyword(s):  
Chromosome Form
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