HETEROCHROMATIN AND MULTIPLE INVERSIONS IN A DROSOPHILA CHROMOSOME

1975 ◽  
Vol 17 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Visut Baimai
Keyword(s):  
Repetitive Dna ◽  
Mitotic Chromosome ◽  
Chromosomal Polymorphism ◽  
Break Point ◽  
Centromeric Heterochromatin ◽  
Gene Recombination ◽  
Heterochromatic Segment ◽  
Chromosomal Break ◽  
Normal Homologue

A chromosomal polymorphism is described from a Maui (Hawaii) population of D. disjuncta. The acquisition of an extra heterochromatic segment in a mitotic chromosome is specifically associated with the presence of multiple inversions in the same chromosome. This suggests the possible effect of a chromosomal break-point within the area of centromeric heterochromatin in causing an increase in the amount of repetitive DNA. The possibility exists that the extra heterochromatin may play a role in the suppression of gene recombination in a certain region of the chromosome and/or in strengthening pairing of the inversion-laden chromosome with its normal homologue. This may reduce the chances of sterility due to nondisjunction during meiosis.

Organization of a cloned repetitive DNA fragment in mosquito genomes (Diptera: Culicidae)

Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 998-1006 ◽  
Author(s):  
A. Kumar ◽  
K. S. Rai
Keyword(s):  
In Situ Hybridization ◽  
Repetitive Dna ◽  
Mitotic Chromosome ◽  
Genomic Organization ◽  
Blot Hybridization ◽  
Dot Blot ◽  
Dot Blot Hybridization ◽  
Dna Organization ◽  
Dna Fragment

The structure and genomic organization of a cloned 5.2-kb repetitive DNA fragment, H-85, isolated from the Aedes albopictus genome have been examined. In situ hybridization of the 3H-labeled H-85 DNA to the meiotic and mitotic chromosome preparations of Ae. albopictus shows that the sequences homologous to H-85 DNA are dispersed throughout the length of all three pairs of chromosomes. A similar pattern of in situ hybridization appears in Aedes seatoi, Aedes flavopictus, and Aedes aegypti. The study shows that the arrangement of sequences in the cloned 5.2-kb fragment is rare in the Ae. albopictus genome. Dot-blot hybridization reveals that the sequences homologous to H-85 DNA are present in 12 species of mosquitoes examined, belonging to six genera in subfamilies Culicinae ad Anophelinae. The H-85 sequences are also present in the genome of Mochlonyx velutinus of the nematocerous family Chaoboridae, earlier proposed as the ancestor of the mosquito family Culicidae. Although the sequences homologous to H-85 DNA are present in different species of mosquitoes, they have diverged in their structure and organization. The cloned 5.2-kb fragment is composed of elements of different and independently evolving repetitive DNA families.Key words: repetitive DNA, organization, mosquitoes.

scholarly journals Expression of p53 in human leukemia and lymphoma

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 113-118 ◽  
Author(s):  
M Prokocimer ◽  
M Shaklai ◽  
HB Bassat ◽  
D Wolf ◽  
N Goldfinger ◽  
...  
Keyword(s):  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
P53 Gene ◽  
Break Point ◽  
Chromosome 17 ◽  
Human Leukemia ◽  
Genomic Changes ◽  
Leukemic Cell Lines ◽  
Myeloid Leukemic Cell ◽  
Chromosomal Break

Abstract Analysis of fresh human tumors have indicated that patients with B type lymphoproliferative diseases and the majority of patients with acute lymphoblastic leukemia (ALL) express elevated levels of p53 production. It is suggested that in these human malignancies, p53 may provide a novel tool for monitoring cancer activity. Conversely, p53 is not expressed in acute myeloid leukemias, myeloproliferative diseases, or myeloid leukemic cell lines. Analysis of the p53 gene structure indicated the existence of similar patterns of p53 restriction fragments in producer and nonproducer cells, which suggests that the p53 gene is not altered in the latter. However, in one case of acute promyelocytic leukemia (APL), we have observed a rearrangement in the p53 gene. Karyotype analysis has indicated that these APL cells do not contain the typical 15;17 translocation. In other APL patients who exhibit a 15;17 translocation, we found no genomic changes of the p53, suggesting that the p53 gene, which was recently mapped to the short arm of chromosome 17 in the human, is not structurally related to the typical chromosomal break point found in the long arm of chromosome 17 of APL patients.

Molecular and cytological characterization of repetitive DNA sequences from the centromeric heterochromatin of Sciara coprophila

Chromosoma ◽  
2011 ◽  
Vol 120 (4) ◽  
pp. 387-397 ◽  
Author(s):  
M. Carmen Escribá ◽  
Patricia G. Greciano ◽  
María Méndez-Lago ◽  
Beatriz de Pablos ◽  
Vladimir A. Trifonov ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Dna Sequences ◽  
Centromeric Heterochromatin ◽  
Repetitive Dna Sequences

scholarly journals The Pontastacus leptodactylus (Astacidae) Repeatome Provides Insight Into Genome Evolution and Reveals Remarkable Diversity of Satellite DNA

2021 ◽  
Vol 11 ◽  
Author(s):  
Ljudevit Luka Boštjančić ◽  
Lena Bonassin ◽  
Lucija Anušić ◽  
Leona Lovrenčić ◽  
Višnja Besendorfer ◽  
...  
Keyword(s):  
Repetitive Dna ◽  
Satellite Dna ◽  
Chromosomal Evolution ◽  
Repetitive Elements ◽  
Centromeric Heterochromatin ◽  
Dna Repeats ◽  
Satellite Repeats ◽  
Interstitial Telomeric Repeats ◽  
Low Coverage ◽  
First Time

Pontastacus leptodactylus is a native European crayfish species found in both freshwater and brackish environments. It has commercial importance for fisheries and aquaculture industries. Up till now, most studies concerning P. leptodactylus have focused onto gaining knowledge about its phylogeny and population genetics. However, little is known about the chromosomal evolution and genome organization of this species. Therefore, we performed clustering analysis of a low coverage genomic dataset to identify and characterize repetitive DNA in the P. leptodactylus genome. In addition, the karyogram of P. leptodactylus (2n = 180) is presented here for the first time consisting of 75 metacentric, 14 submetacentric, and a submetacentric/metacentric heteromorphic chromosome pair. We determined the genome size to be at ~18.7 gigabase pairs. Repetitive DNA represents about 54.85% of the genome. Satellite DNA repeats are the most abundant type of repetitive DNA, making up to ~28% of the total amount of repetitive elements, followed by the Ty3/Gypsy retroelements (~15%). Our study established a surprisingly high diversity of satellite repeats in P. leptodactylus. The genome of P. leptodactylus is by far the most satellite-rich genome discovered to date with 258 satellite families described. Of the five mapped satellite DNA families on chromosomes, PlSAT3-411 co-localizes with the AT-rich DAPI positive probable (peri)centromeric heterochromatin on all chromosomes, while PlSAT14-79 co-localizes with the AT-rich DAPI positive (peri)centromeric heterochromatin on one chromosome and is also located subterminally and intercalary on some chromosomes. PlSAT1-21 is located intercalary in the vicinity of the (peri)centromeric heterochromatin on some chromosomes, while PlSAT6-70 and PlSAT7-134 are located intercalary on some P. leptodactylus chromosomes. The FISH results reveal amplification of interstitial telomeric repeats (ITRs) in P. leptodactylus. The prevalence of repetitive elements, especially the satellite DNA repeats, may have provided a driving force for the evolution of the P. leptodactylus genome.

scholarly journals Expression of p53 in human leukemia and lymphoma

Blood ◽  
1986 ◽  
Vol 68 (1) ◽  
pp. 113-118 ◽  
Author(s):  
M Prokocimer ◽  
M Shaklai ◽  
HB Bassat ◽  
D Wolf ◽  
N Goldfinger ◽  
...  
Keyword(s):  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
P53 Gene ◽  
Break Point ◽  
Chromosome 17 ◽  
Human Leukemia ◽  
Genomic Changes ◽  
Leukemic Cell Lines ◽  
Myeloid Leukemic Cell ◽  
Chromosomal Break

Analysis of fresh human tumors have indicated that patients with B type lymphoproliferative diseases and the majority of patients with acute lymphoblastic leukemia (ALL) express elevated levels of p53 production. It is suggested that in these human malignancies, p53 may provide a novel tool for monitoring cancer activity. Conversely, p53 is not expressed in acute myeloid leukemias, myeloproliferative diseases, or myeloid leukemic cell lines. Analysis of the p53 gene structure indicated the existence of similar patterns of p53 restriction fragments in producer and nonproducer cells, which suggests that the p53 gene is not altered in the latter. However, in one case of acute promyelocytic leukemia (APL), we have observed a rearrangement in the p53 gene. Karyotype analysis has indicated that these APL cells do not contain the typical 15;17 translocation. In other APL patients who exhibit a 15;17 translocation, we found no genomic changes of the p53, suggesting that the p53 gene, which was recently mapped to the short arm of chromosome 17 in the human, is not structurally related to the typical chromosomal break point found in the long arm of chromosome 17 of APL patients.

scholarly journals NATURE AND CONSEQUENCES OF INDUCED CHROMOSOME DAMAGE IN MAMMALS

Genetics ◽  
1974 ◽  
Vol 78 (1) ◽  
pp. 173-186
Author(s):  
A G Searle
Keyword(s):  
Germ Cells ◽  
Primary Spermatocyte ◽  
Break Point ◽  
Complete Separation ◽  
Point Of View ◽  
Centromeric Heterochromatin ◽  
General Tendency ◽  
Male Sterile ◽  
Balanced Translocation ◽  
Reciprocal Translocations

ABSTRACT There are marked qualitative and quantitative differences in the patterns of chromosomal damage observed after irradiation of spermatogonia, spermatozoa and oocytes of mice. These differences often result from reduced or zero transmission of particular classes of abberration arising in pre-meiotic germ cells. Probably this is the reason why the level of X-chromosomal and autosomal monosomy is not increased after spermatogonial irradiation. Similarly, the reduced transmission of certain d-se deficiencies may help to explain their low F1 frequency after pre-meiotic as compared with later irradiation. Spermatozoal irradiation has revealed no Robertsonian translocations, but has produced some types of reciprocal translocations which apparently are not transmitted to the F1 after spermatogonial treatment because they prevent maturation of the male pre-meiotic germ cell. Thus they cause sterility in males, but not in females. They include X-autosome and Y-autosome translocations, those giving a metacentric or sub-metacentric chromosome (with reciprocal product present) and those in which one break-point is in or near the centromeric heterochromatin while the other is more distally placed. This last group (which grades into male sub-fertile conditions) gives a preponderance of chain configurations (often with one separate univalent) in heterozygotes of both sexes at meiosis and a high incidence of somatic marker chromosomes. Nondisjunction associated with the univalent generates tertiary trisomics, which are usually male-sterile also and may show phenotypic abnormalities. Sterile males with complete separation of X and Y chromosomes have also been reported after mutagenic treatment of meiotic and post-meiotic germ cells. Such separation seems to prevent a primary spermatocyte from forming a secondary one. The usual derivation (in mouse and man) of tertiary trisomics from mothers rather than from fathers may be due to a similar block, together with a general tendency for male heterozygotes for the parental balanced translocation to be sterile or sub-fertile. Mature oocytes tend to resemble spermatoza in the types of aberration produced by irradiation, which include the male-sterile translocation, but more data are needed. Many of the aberrations described contribute to the human cytogenetic load and can be studied in the mouse from this point of view.

Chromosome polymorphism in Holochilus venezuelae (Rodentia: Cricetidae): C- and G-bands

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 13-18 ◽  
Author(s):  
N. Sangines ◽  
M. Aguilera
Keyword(s):  
Pericentric Inversion ◽  
Chromosomal Polymorphism ◽  
Centric Fusion ◽  
Centromeric Heterochromatin ◽  
Fusion Product ◽  
Chromosome Polymorphism ◽  
Banding Patterns ◽  
Submetacentric Chromosome ◽  
Group A ◽  
Fusion Type

Karyological analysis of C- and G-banding patterns of 44 specimens of Holochilus venezuelae revealed six distinct karyomorphs, which were designated as follows: I (2n = 44; fundamental number (FN) = 56); II (2n = 45; FN = 58); IV (2n = 43; FN = 56);V(2n = 44; FN = 58); IV-a(2n = 42; FN = 56); and V-a (2n = 44; FN = 58). This chromosomal polymorphism is interpreted as the result of (i) one or two Robertsonian changes of the centric-fusion type, originating from one member of chromosome pair 10 and one of pair 11 (in karyotypes IV and V) and two metacentric chromosomes from pairs 10 and 11 (in karyotype IV-a); (ii) one pericentric inversion (in karyotype V-a) forming one submetacentric chromosome from the metacentric fusion product described above; and (iii) the presence of B chromosomes, which are almost completely heterochromatic and do not pair with any member of group A. The pattern of C-banding reveals that the first five pairs of metacentric chromosomes contain very little centromeric heterochromatin, while pair 6 and the fusion chromosomes (10/11 F) present a thick band. Extensive homology was found between G-banding patterns of Holochilus brasiliensis from Brazil and H. venezuelae. These facts support the hypothesis of a karyotypic evolution via centric fusions previously proposed for this genus.Key words: accessory chromosome, C- and G-banding, polymorphism, Holochilus venezuelae.

DNA methylation in satellite repeats disorders

2019 ◽  
Vol 63 (6) ◽  
pp. 757-771 ◽  
Author(s):  
Claire Francastel ◽  
Frédérique Magdinier
Keyword(s):  
Dna Methylation ◽  
Human Genome ◽  
Repetitive Dna ◽  
Dna Sequences ◽  
Satellite Repeats ◽  
Tremendous Progress ◽  
Genes Encoding ◽  
Dna Elements ◽  
Near Future

Abstract Despite the tremendous progress made in recent years in assembling the human genome, tandemly repeated DNA elements remain poorly characterized. These sequences account for the vast majority of methylated sites in the human genome and their methylated state is necessary for this repetitive DNA to function properly and to maintain genome integrity. Furthermore, recent advances highlight the emerging role of these sequences in regulating the functions of the human genome and its variability during evolution, among individuals, or in disease susceptibility. In addition, a number of inherited rare diseases are directly linked to the alteration of some of these repetitive DNA sequences, either through changes in the organization or size of the tandem repeat arrays or through mutations in genes encoding chromatin modifiers involved in the epigenetic regulation of these elements. Although largely overlooked so far in the functional annotation of the human genome, satellite elements play key roles in its architectural and topological organization. This includes functions as boundary elements delimitating functional domains or assembly of repressive nuclear compartments, with local or distal impact on gene expression. Thus, the consideration of satellite repeats organization and their associated epigenetic landmarks, including DNA methylation (DNAme), will become unavoidable in the near future to fully decipher human phenotypes and associated diseases.

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