scholarly journals The intranuclear relationship between centromere volume and chromosome size in Festuca scariosa X drymeja

1981 ◽  
Vol 47 (1) ◽  
pp. 117-125
Author(s):  
G. Jenkins ◽  
M.D. Bennett
Keyword(s):  
Serial Section ◽  
Chromosome Length ◽  
Individual Chromosome ◽  
Chromosome Size ◽  
Preferential Pairing ◽  
Frequency Distributions ◽  
Positive Correlation ◽  
Serial Section Reconstruction

In the hybrid Festuca scarisoa X drymeja where pairing is incomplete at pachytene, there is preferential pairing between the longer chromosomes of the complement. EM serial-section reconstruction of nuclei at zygotene and pachytene reveals that there is equally pronounced preferential pairing between larger centromeres. This evidence suggests that the longer chromosomes have large centromeres and that centromere volume is correlated with chromosome length. Confirmation of this comes from the comparison of the frequency distributions of observed centromere volumes and those predicted on the basis of chromosome length. Although there is a positive correlation between centromere volume and chromosome length, it is not possible to identify the centromeres of each individual chromosome within the complement because (a) the differences between the lengths of each chromosome are small and (b) the estimates of relative centromere volumes vary significantly between cells.

scholarly journals Mammalian chromosome–telomere length dynamics

2018 ◽  
Vol 5 (7) ◽  
pp. 180492 ◽  
Author(s):  
Amy R. Klegarth ◽  
Dan T. A. Eisenberg
Keyword(s):  
Telomere Length ◽  
Significant Relationship ◽  
Chromosome Length ◽  
Individual Chromosome ◽  
Chromosome Size ◽  
Lag Effects ◽  
Phylogenetic Framework ◽  
Telomere Biology ◽  
Evolutionary Lag ◽  
Positive Correlations

Individual chromosome arms have specific individual telomere lengths (TLs). Past studies within species have shown strong positive correlations between individual chromosome length and TL at that chromosome. While the reasons for these associations are unclear, the strength and consistency of the associations across disparate taxa suggest that this is important to telomere biology and should be explored further. If TL is primarily determined by chromosome length, then chromosome length should be considered and controlled for in cross-species analyses of TL. Here, we employ a cross-species approach to explore whether the chromosome length–TL association observed intraspecifically is a determinant of mean TL across species. Data were compiled from two studies characterizing TL across a range of mammalian taxa and analysed in a phylogenetic framework. We found no significant relationship between TL and chromosome size across mammals or within mammalians orders. The pattern trends in the expected direction and we suggest may be masked by evolutionary lag effects.

scholarly journals Nucleic acid content and Chromosome morphology in Chrysanthemum

1969 ◽  
Vol 13 (3) ◽  
pp. 241-250 ◽  
Author(s):  
G. J. Dowrick ◽  
A. S. El Bayoumi
Keyword(s):  
Nucleic Acid ◽  
Chromosome Number ◽  
Dna Content ◽  
Chromosome Numbers ◽  
Chromosome Length ◽  
Chromosome Morphology ◽  
Nucleic Acid Content ◽  
Chromosome Size ◽  
Dna Contents ◽  
The Relationship

1. The DNA contents of twenty-eight different species and forms of Chrysanthemum have been measured by photometry. It is shown that there are large differences in DNA content between some species with identical chromosome numbers.2. The DNA contents of natural polyploids are frequently not those expected when comparison is made with diploid forms of the same species. The DNA contents of induced polyploids are those expected.3. Chromosome length and volume are positively correlated with DNA content.4. The relationship between chromosome number, chromosome size, DNA content and gene number is considered, and it is suggested that the differences in DNA content may result from the presence of differing amounts of genetically inactive DNA in the chromosomes.

scholarly journals The Incidence of Mosaicism for Individual Chromosome in Human Blastocysts Is Correlated With Chromosome Length

2021 ◽  
Vol 11 ◽  
Author(s):  
Tzu-Hsuan Chuang ◽  
Ya-Ping Chang ◽  
Meng-Ju Lee ◽  
Huai-Ling Wang ◽  
Hsing-Hua Lai ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Chromosome Length ◽  
Small Sample ◽  
Individual Chromosome ◽  
Preimplantation Genetic Testing ◽  
Comprehensive Chromosome Screening ◽  
Mosaic Embryo ◽  
Group A ◽  
Group B ◽  
Mosaic Aneuploidy

Mosaicism, known as partial aneuploidies, mostly originates from mitotic errors during the post-zygotic stage; it consists of different cell lineages within a human embryo. The incidence of mosaicism has not been shown to correlate with maternal age, and its correlation with individual chromosome characteristics has not been well investigated. In this study, the results of preimplantation genetic testing for aneuploidy (PGT-A) derived from 4,036 blastocysts (930 IVF couples) were collected from 2015 to 2017. Via next-generation sequencing for comprehensive chromosome screening, embryo ploidy was identified as aneuploid, mosaic, and euploid. Total mosaicism was classified into two categories: “mosaic euploid/aneuploidy” (with mosaic aneuploidy between 20 and 80%) and “mosaic and aneuploidy” (a uniformly abnormal embryo superimposed with mosaic aneuploidies). Frequency of mosaicism was analyzed according to the function of chromosomal lengths, which divides involved chromosomes into three groups: group A (156–249 Mb), group B (102–145 Mb), and group C (51–90 Mb). The results show that the aneuploidy was more frequent in group C than in group A and group B (A: 23.7%, B: 35.1, 41.2%, p < 0.0001), while the mosaicism was more frequent in group A and group B than in group C [(Mosaic euploid/aneuploid) A: 14.6%, B: 12.4%, C: 9.9%, p < 0.0001; (mosaic and aneuploid) A: 21.3%, B: 22.9%, C: 18.9%, p < 0.0001; (Total mosaicism) A: 35.9%, B: 35.3%, C: 28.8%, p < 0.0001]. The significantly higher frequency of aneuploidy was on the shorter chromosome (< 90 Mb), and that of mosaicism was on the longer chromosomes (> 100 Mb). The length association did not reach significance in the patients with advanced age (≥ 36 years), and of the chromosome-specific mosaicism rate, the highest prevalence was on chromosome 14 (5.8%), 1 (5.7%), and 9 (5.6%). Although the length association was observed via group comparison, there may be affecting mechanisms other than chromosomes length. Eventually, twenty patients with mosaic embryo cryotransfers resulted in six live births. No significant correlation was observed between the transfer outcomes and chromosome length; however, the analysis was limited by small sample size.

Automated image segmentation and serial section reconstruction in microscopy

1990 ◽  
Vol 158 (2) ◽  
pp. 187-196 ◽  
Author(s):  
V. A. Moss ◽  
D. McEwan Jenkinson ◽  
H. Y. Elder
Keyword(s):  
Image Segmentation ◽  
Serial Section ◽  
Serial Section Reconstruction

Homozygous and heterozygous homologous chromosomes: effects on preferential pairing and recombination frequency in wheat

Genome ◽  
1988 ◽  
Vol 30 (3) ◽  
pp. 336-340 ◽  
Author(s):  
E. Y. Suárez ◽  
L. Gorgoschidse ◽  
F. Sacco ◽  
H. Saione
Keyword(s):  
Genetic Analysis ◽  
Recombination Frequency ◽  
Preferential Pairing ◽  
Homologous Chromosomes ◽  
Positive Correlation

Trisomics for chromosomes 1A and 6B of wheat backcrossed to euploids showed progeny with unexpected segregation frequencies (cytological and genetical) that can be attributed to preferential pairing between homologues. Recombination frequency between the centromere and a gene for mildew reaction of chromosome 1A showed an increase from the first to the second backcross that could be attributed to a positive correlation between homozygosity and the degree of pairing between homologous chromosomes. The use of wheat trisomics for genetic analysis is also discussed.Key words: preferential pairing, trisomic segregation, wheat cytogenetics, recombination frequency, pathogen reaction.

scholarly journals Structure of the Golgi and Distribution of Reporter Molecules at 20°C Reveals the Complexity of the Exit Compartments

2002 ◽  
Vol 13 (8) ◽  
pp. 2810-2825 ◽  
Author(s):  
Mark S. Ladinsky ◽  
Christine C. Wu ◽  
Shane McIntosh ◽  
J. Richard McIntosh ◽  
Kathryn E. Howell
Keyword(s):  
Golgi Complex ◽  
Serial Section ◽  
Immunogold Labeling ◽  
The Other ◽  
Dominant Feature ◽  
In Trans ◽  
Golgi Structure ◽  
Normal Thickness ◽  
Em Tomography ◽  
Serial Section Reconstruction

Incubating cells at 20°C blocks transport out of the Golgi complex and amplifies the exit compartments. We have used the 20°C block, followed by EM tomography and serial section reconstruction, to study the structure of Golgi exit sites in NRK cells. The dominant feature of Golgi structure in temperature-blocked cells is the presence of large bulging domains on the three trans-most cisternae. These domains extend laterally from the stack and are continuous with “cisternal” domains that maintain normal thickness and alignment with the other stacked Golgi cisternae. The bulging domains do not resemble the perpendicularly extending tubules associated with the trans-cisternae of control cells. Such tubules are completely absent in temperature-blocked cells. The three cisternae with bulging domains can be identified as trans by their association with specialized ER and the presence of clathrin-coated buds on the trans-most cisterna only. Immunogold labeling and immunoblots show a significant degradation of a medial- and a trans-Golgi marker with no evidence for their redistribution within the Golgi or to other organelles. These data suggest that exit from the Golgi occurs directly from three trans-cisternae and that specialized ER plays a significant role in trans-Golgi function.

Sign in / Sign up

Export Citation Format

Share Document