Variation in the heterochromatin and nucleolar organizing regions of Allium subvillosum L. (Liliaceae)

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 779-784 ◽  
Author(s):  
M. Jamilena ◽  
C. Ruiz Rejón ◽  
M. Ruiz Rejón
Keyword(s):  
Chromosome Pair ◽  
Wild Population ◽  
Supernumerary Chromosome ◽  
Fluorescence Pattern ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Organizing Region ◽  
The Third ◽  
Chromosome Segments

Two kinds of polymorphisms have been found in a wild population of Allium subvillosum L. (Liliaceae): (i) extra C-bands and supernumerary chromosome segments on three chromosome pairs and (ii) the absence of the nucleolar organizing region (NOR) in one member of the third chromosome pair (there are two other NOR-bearing chromosome pairs in the karyotype of this species). The fluorescence pattern (chromomycin A3 (CMA3) positive and 4,6-diamidino-2-phenylindole (DAPI) negative) of the extra heterochromatin is similar to that of the standard. The absence of the NOR on the third chromosome pair is related to a variation in the NOR-associated heterochromatin (the chromosomes with no NOR do not have the distal C-band from the satellite, but the proximal C-band may be present). The characteristics of the karyotype of this species, its heterochromatin distribution, and the possible mechanisms by which the polymorphisms may originate are discussed.Key words: Allium, supernumerary segments, heterochromatin, polymorphisms, nucleolar organizing regions.

Structure and variability of nucleolar organizer regions in Parodontidae fish

1984 ◽  
Vol 26 (5) ◽  
pp. 564-568 ◽  
Author(s):  
Orlando Moreira-Filho ◽  
Luiz Antonio Carlos Bertollo ◽  
Pedro Manoel Galetti Jr.
Keyword(s):  
Chromosome Pair ◽  
Constitutive Heterochromatin ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Mitotic Chromosomes ◽  
Homozygous Condition ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Chromosome

Nucleolar organizer regions (NORs) were studied in mitotic chromosomes of four species of fish of family Parodontidae: Parodon tortuosus, Apareiodon affinis, Apareiodon ibitiensis, and Apareiodon piracicabae. All four species exhibited only a single nucleolar chromosome pair in their karyotypes. Intraspecific differences were observed in the size of these chromosomes; however, these were not very clear for A. affinis and A. piracicabae, Apareiodon piracicabae exhibited two clearly visible NORs in each of the nucleolar chromosomes, which was the only configuration practically found in this species. This trait therefore predominates in a homozygous condition in the population investigated. Regions of constitutive heterochromatin adjacent to the two NORs were detected. Possible mechanisms that may have originated the two NORs are discussed.Key words: nucleolar organizing regions, fish.

scholarly journals Detailed molecular cytogenetic characterisation of the myeloid cell line U937 reveals the fate of homologous chromosomes and shows that centromere capture is a feature of genome instability

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Ruth N. MacKinnon ◽  
Joanne Peverall ◽  
Lynda J. Campbell ◽  
Meaghan Wall
Keyword(s):  
Cell Line ◽  
Chromosome Pair ◽  
Fusion Gene ◽  
Genome Instability ◽  
Snp Array ◽  
Myeloid Cell ◽  
Chromosome 20 ◽  
Myeloid Cell Line ◽  
Multicolour Fish ◽  
Chromosome Segments

Abstract Background The U937 cell line is widely employed as a research tool. It has a complex karyotype. A PICALM-MLLT10 fusion gene formed by the recurrent t(10;11) translocation is present, and the myeloid common deleted region at 20q12 has been lost from its near-triploid karyotype. We carried out a detailed investigation of U937 genome reorganisation including the chromosome 20 rearrangements and other complex rearrangements. Results SNP array, G-banding and Multicolour FISH identified chromosome segments resulting from unbalanced and balanced rearrangements. The organisation of the abnormal chromosomes containing these segments was then reconstructed with the strategic use of targeted metaphase FISH. This provided more accurate karyotype information for the evolving karyotype. Rearrangements involving the homologues of a chromosome pair could be differentiated in most instances. Centromere capture was demonstrated in an abnormal chromosome containing parts of chromosomes 16 and 20 which were stabilised by joining to a short section of chromosome containing an 11 centromere. This adds to the growing number of examples of centromere capture, which to date have a high incidence in complex karyotypes where the centromeres of the rearranged chromosomes are identified. There were two normal copies of one chromosome 20 homologue, and complex rearrangement of the other homologue including loss of the 20q12 common deleted region. This confirmed the previously reported loss of heterozygosity of this region in U937, and defined the rearrangements giving rise to this loss. Conclusions Centromere capture, stabilising chromosomes pieced together from multiple segments, may be a common feature of complex karyotypes. However, it has only recently been recognised, as this requires deliberate identification of the centromeres of abnormal chromosomes. The approach presented here is invaluable for studying complex reorganised genomes such as those produced by chromothripsis, and provides a more complete picture than can be obtained by microarray, karyotyping or FISH studies alone. One major advantage of SNP arrays for this process is that the two homologues can usually be distinguished when there is more than one rearrangement of a chromosome pair. Tracking the fate of each homologue and of highly repetitive DNA regions such as centromeres helps build a picture of genome evolution. Centromere- and telomere-containing elements are important to deducing chromosome structure. This study confirms and highlights ongoing evolution in cultured cell lines.

Karyotype, C-banding, chromosomal location of active nucleolar organizing regions, and B-chromosomes in Lasius niger (Hymenoptera, Formicidae)

Genome ◽  
1990 ◽  
Vol 33 (2) ◽  
pp. 267-272 ◽  
Author(s):  
T. Palomeque ◽  
E. Chica ◽  
R. Díaz de la Guardia
Keyword(s):  
Germ Cells ◽  
Chromosomal Location ◽  
Ganglion Cells ◽  
Cerebral Ganglion ◽  
B Chromosomes ◽  
Lasius Niger ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Organizing Region ◽  
C Banding ◽  
Numerical Variation

The karyotype of Lasius niger (n = 15) was analysed using C-banding and observation of nucleolar organizing region (NOR) sites. C-banding showed the existence of heterochromatin in the paracentromeric regions of all chromosomes. Two sites with primary NORs were found in chromosomes 6 and 8. Chromosome 13 showed a secondary NOR. In both cases, the NORs were located in the paracentromeric region. B-chromosomes were found in male and female germ cells. They exhibited intra- and inter-individual numerical variation. No B-chromosomes were observed in somatic cells (cerebral ganglion cells) of all castes. The Bs are telocentric, small, and clearly distinguishable from the regular members of the complement. They show positive heteropycnosis in meiotic prophase and they are highly C-band positive. The activity of NORs does not change when Bs are present. Several aspects of the behaviour of these Bs are examined.Key words: C-bands, nucleolar organizing region (primary), nucleolar oganizing region (secondary), B-chromosomes, Formicidae.

Cytogenetic studies in gomphocerine grasshoppers. II. Chromosomal location of active nucleolar organizing regions

1986 ◽  
Vol 28 (4) ◽  
pp. 540-544 ◽  
Author(s):  
Josefa Cabrero ◽  
Juan Pedro M. Camacho
Keyword(s):  
Chromosomal Location ◽  
Nucleolar Organizer ◽  
X Chromosomes ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Organizing Region ◽  
Primary Activity ◽  
Cytogenetic Studies ◽  
Almost All ◽  
Active Nors

Nucleolar organizing region (NOR) location has been studied in 20 species of gomphocerine grasshoppers. In the 17 species with 2n (♀) = 17, the largest number carry an active NOR on the L2, L3, and X chromosomes. The M4, M5, M6, and S8 show NOR activity in some species, but the L1 and M7 do not carry a NOR in any. While almost all NORs on L2, L3, and X show primary activity, a majority of these on the M4, M5, M6, and S8 are secondary and express a nucleolus only in a minority of male meiocytes. The NORs are located preferentially at particular chromosomal sites; primary active NORs prevail in interstitial locations, while secondary active NORs predominate in paracentromeric locations. In the majority of the species analyzed in this report, primary and secondary active NORs coincide with C-bands. Euchorthippus pulvinatus is an exception; here NORs do not seem to be related to C-bands. However, the nucleolar-associated heterochromatin in this species can be demonstrated by a N-banding technique.Key words: nucleolar organizer, NOR (primary), C-bands, heterochromatin, NOR (secondary).

A supernumerary chromosome segment in Locusta migratoria

Genome ◽  
1993 ◽  
Vol 36 (5) ◽  
pp. 919-923 ◽  
Author(s):  
M. C. Pardo ◽  
E. Viseras ◽  
J. Cabrero ◽  
J. P. M. Camacho
Keyword(s):  
Dna Sequences ◽  
Locusta Migratoria ◽  
Supernumerary Chromosome ◽  
Rrna Genes ◽  
Single Female ◽  
Nucleolar Organizing Regions ◽  
Extra Segment ◽  
Accumulation Mechanism ◽  
Nucleolus Organiser ◽  
Nucleolus Organiser Region

A single female of Locusta migratoria was found to be heterozygous for a supernumerary heterochromatic segment distally located on the M6 autosome close to its nucleolus organiser region (NOR). Reactions to several chromosome banding techniques revealed its heterochromatic nature and its composition of GC-rich DNA sequences and likewise the NORs in this species. This suggests an origin for the extra segment by amplification of GC-rich DNA sequences contained in the distal NOR of the M6 chromosome, which is reinforced by the observation that the NOR of segmented M6 chromosomes produced the larger nucleolus in embryo prophase cells, such as would be expected from the presence of rRNA genes in the extra segment. No accumulation mechanism was detected in this female after analyzing the 213 embryo offspring produced, but an increase in the number of nucleoli per interphase nucleus was noted in heterozygous embryos in respect to standard homozygous ones.Key words: Locusta migratoria, supernumerary segments, nucleolar organizing regions, heterochromatin.

scholarly journals Chiasma redistribution in presence of supernumerary chromosome segments in grasshoppers: dependence on the size of the extra segment

Heredity ◽  
1987 ◽  
Vol 58 (3) ◽  
pp. 409-412 ◽  
Author(s):  
Jesús Navas-Castillo ◽  
Josefa Cabrero ◽  
Juan Pedro M Camacho
Keyword(s):  
Supernumerary Chromosome ◽  
Extra Segment ◽  
Chromosome Segments

Karyological divergence of a Moldovan population of Rana dalmatina Bonaparte, 1838

2010 ◽  
Vol 31 (3) ◽  
pp. 435-438 ◽  
Author(s):  
Orfeo Picariello ◽  
Gaetano Odierna ◽  
Emilio Balletto ◽  
Cristina Giacoma ◽  
Agnese Petraccioli
Keyword(s):  
Chromosome Pair ◽  
Molecular Similarity ◽  
Rrna Gene ◽  
Karyological Study ◽  
Mitochondrial Rrna ◽  
The Third ◽  
Satellite Sequences ◽  
Significant Difference ◽  
Staining Methods ◽  
Rana Dalmatina

AbstractA karyological study conducted by both conventional and banding staining methods (Ag-NOR-, CMA3, and C-banding) evidenced a peculiar heterochromatin pattern on chromosomes of Moldovan specimens of the agile frog, Rana dalmatina. As is normal for all agile frogs, the Moldovan population presented 2n = 26 chromosomes, with NOR loci on the short arms of the third chromosome pair, but differed in showing heavy centromeric, CMA3 positive C-bands on the seventh chromosome pair, and light centromeric, DAPI positive C-bands on five chromosome pairs. In contrast, Moldovan specimens showed no significant difference in two segments of the 16S mitochondrial rRNA gene and in the S1 satellite DNA sequence and organization, in comparison with the GenBank deposited 16S rDNA and S1 DNA satellite sequences of R. dalmatina. Molecular similarity and chromosomal differences between agile frogs from Moldovan and extra-Moldovan populations are discussed.

Effects of restriction endonucleases on nucleolar organizing regions in the ant Tapinoma nigerrimum

Genome ◽  
1998 ◽  
Vol 41 (6) ◽  
pp. 872-875
Author(s):  
P Lorite ◽  
T Palomeque
Keyword(s):  
Ribosomal Rna ◽  
Chromosome Region ◽  
Restriction Endonucleases ◽  
Limiting Factor ◽  
Naked Dna ◽  
Nucleolar Organizing Regions ◽  
Nucleolar Organizing Region ◽  
Partial Digestion ◽  
Tapinoma Nigerrimum

The effects of some restriction endonucleases (REs) on the nucleolar organizing regions and on the genes for ribosomal RNA (rDNA) were analyzed using the nucleolar organizing region of the chromosome 6 of Tapinoma nigerrimum as an experimental model, since, in accordance with previous studies, the genes for ribosomal RNA seem to be present only in this chromosome. In situ non-digestion of the nucleolar organizing region was observed when EcoRI and HindIII were used. However, very evident digestion and partial digestion respectively were observed when HaeIII and Tru9I were used. Southern blot analysis realized on naked DNA digested with the same REs and using rDNA of Drosophila melanogaster as probe showed that there are target sequences for these enzymes in the rDNA. In accordance with the results obtained, the rDNA is poor in EcoRI and HindIII sequences, contains moderate amounts of Tru9I sequences, and is rich in HaeIII sequences. All the data obtained suggest that in the nucleolar organizing region of Tapinoma nigerrimum, the major, if not the only, limiting factor affecting in situ digestion by the REs used is the presence and frequency of their specific restriction targets. Consequently, extraction of DNA from this chromosome region depends on the size of the fragments originated.Key words: chromosome banding, Formicidae, NORs, rDNA, restriction endonucleases.

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