scholarly journals The number and location of genes for 5S ribonucleic acid within the genome of Drosophila melanogaster

1971 ◽  
Vol 123 (2) ◽  
pp. 227-233 ◽  
Author(s):  
R. V. Quincey
Keyword(s):  
Drosophila Melanogaster ◽  
Ribonucleic Acid ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Haploid Genome ◽  
28S Rrna ◽  
Wild Type ◽  
5S Rna ◽  
Type D

DNA was prepared from wild-type and two mutant stocks of Drosophila melanogaster that differed in their dosage of the nucleolar organizer region. The relative amounts of DNA from the nucleolar organizer region in these preparations of DNA were determined by hybridization with 3H-labelled 28S rRNA. As expected, the amount of 3H-labelled 28S rRNA that hybridized was directly related to the dosage of nucleolar organizer region. No positive correlation was observed between the amount of 3H-labelled 5S RNA that hybridized and the dosage of nucleolar organizer region. Thus genes for 5S RNA are located primarily, if not exclusively, outside the nucleolar organizer region. The haploid genome of the wild-type D. melanogaster used in this work has 106 genes for 28S rRNA and 96–105 genes for 5S RNA.

scholarly journals GENETIC ANALYSIS OF THE 5S RNA GENES IN DROSOPHILA MELANOGASTER

Genetics ◽  
1975 ◽  
Vol 81 (3) ◽  
pp. 515-523
Author(s):  
James D Procunier ◽  
Kenneth D Tartof
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Rna ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Ribosomal Rna Genes ◽  
Chromosome 2 ◽  
Wild Type ◽  
5S Rna ◽  
5S Rna Genes ◽  
Rna Genes

ABSTRACT The 5S RNA genes of Drosophila melanogaster in either an isogenic wild-type or a multiply inverted (SM1) chromosome 2 increase their multiplicity when opposite a deficiency for the 5S gene site. This is analogous to the compensation phenomenon previously described for the 18S and 28S ribosomal RNA genes of the X chromosome nucleolus organizer region. Molecular hybridization of 5S RNA to DNA containing various doses of the 56F1-9 region of chromosome 2 demonstrates that most, if not all, of the 5S genes reside in or near this region. Also, a deficiency missing approximately one-half of the wild-type number of 5S genes was isolated and genetically localized. This mutant has a phenotype like that of bobbed, a mutant known to be partially deficient in 18S and 28S ribosomal RNA genes. Finally, we report the existence of a chromosomal rearrangement which splits the second chromosome into two segments, each containing 5S DNA.

Molecular analysis of a NOR site polymorphism in brown trout (Salmo trutta): organization of rDNA intergenic spacers

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 916-922 ◽  
Author(s):  
Jaime Castro ◽  
Laura Sánchez ◽  
Paulino Martínez ◽  
Stefania De Lucchini ◽  
Irma Nardi
Keyword(s):  
Salmo Trutta ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Initial Step ◽  
Molecular Organization ◽  
Rrna Genes ◽  
28S Rrna ◽  
Intergenic Spacers ◽  
Brown Trout Salmo Trutta

Using restriction endonuclease mapping, we have analyzed the organization of rDNA (DNA coding for ribosomal RNA (rRNA)) units in the salmonid fish Salmo trutta, as an initial step toward understand the molecular basis of a nucleolar organizer region (NOR) site polymorphism detected in this species. The size of the rDNA units ranged between 15 and 23 kb, with remarkable variation both within individuals and between populations. Three regions of internal tandem repetitiveness responsible for this length polymorphism were located to the intergenic spacers. NOR site polymorphic individuals showed a higher number of length classes, in some cases forming a complete 1 kb fragment ladder. The amount of rRNA genes was as much as 8-fold higher in polymorphic individuals compared with standard individuals. All individuals from the most polymorphic population showed a 14-kb insertion of unknown nature in a small proportion (below 25%) of the 28S rRNA genes.Key words: rRNA genes, repetitive elements, molecular organization, rDNA amount.

Quantitative analysis of the formation of nucleoli in Locusta migratoria

1986 ◽  
Vol 28 (2) ◽  
pp. 207-218 ◽  
Author(s):  
M. Diez ◽  
M. J. Puertas
Keyword(s):  
Mathematical Model ◽  
Quantitative Analysis ◽  
Locusta Migratoria ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Lower Probability ◽  
Wild Type ◽  
Differential Activation ◽  
Model Fits

At meiosis of Locusta migratoria, zero, one, or two nucleoli per long (L), medium (M), or short (S) nucleolar organizer region (NOR) bivalent can be clearly seen using an Ag-NOR technique. Diplotene cells with zero to six nucleoli were observed, whose distribution fitted a normal one. However, the distribution of nucleoli in the particular bivalents was not at random. A mathematical model was developed in an attempt to explain this differential activation of nucleoli. The model is based on the assumption that the activation of nucleoli is sequential following successive rounds, in such a way that the probability of a particular L, M, or S nucleolus being activated depends on the type of nucleoli previously activated. The nucleoli activated per cell tend to be distributed among bivalents, and the activation of a second nucleolus in a bivalent has a lower probability than the first one of any bivalent, generating interference. The model was developed for wild-type individuals and it was also applied to mutants that showed a distribution of nucleoli different from wild types, i.e., individuals carrying a translocation between two NOR chromosomes and asynaptic mutants. In both cases the model fits with the observed results. This suggests its general validity.Key words: nucleolus, Locusta, translocation, asynapsis.

scholarly journals Comparative FISH analysis of Senna tora tandem repeats revealed insights into the chromosome dynamics in Senna

2021 ◽  
Vol 43 (3) ◽  
pp. 237-249 ◽  
Author(s):  
Thanh Dat Ta ◽  
Nomar Espinosa Waminal ◽  
Thi Hong Nguyen ◽  
Remnyl Joyce Pellerin ◽  
Hyun Hee Kim
Keyword(s):  
Tandem Repeats ◽  
Chromosomal Rearrangements ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Pericentromeric Region ◽  
Its2 Sequence ◽  
Fish Analysis ◽  
Chromosomal Distribution ◽  
Chromosome Dynamics

Abstract Background DNA tandem repeats (TRs) are often abundant and occupy discrete regions in eukaryotic genomes. These TRs often cause or generate chromosomal rearrangements, which, in turn, drive chromosome evolution and speciation. Tracing the chromosomal distribution of TRs could therefore provide insights into the chromosome dynamics and speciation among closely related taxa. The basic chromosome number in the genus Senna is 2n = 28, but dysploid species like Senna tora have also been observed. Objective To understand the dynamics of these TRs and their impact on S. tora dysploidization. Methods We performed a comparative fluorescence in situ hybridization (FISH) analysis among nine closely related Senna species and compared the chromosomal distribution of these repeats from a cytotaxonomic perspective by using the ITS1-5.8S-ITS2 sequence to infer phylogenetic relationships. Results Of the nine S. tora TRs, two did not show any FISH signal whereas seven TRs showed similar and contrasting patterns to other Senna species. StoTR01_86, which was localized in the pericentromeric regions in all S. tora, but not at the nucleolar organizer region (NOR) site, was colocalized at the NOR site in all species except in S. siamea. StoTR02_7_tel was mostly localized at chromosome termini, but some species had an interstitial telomeric repeat in a few chromosomes. StoTR05_180 was distributed in the subtelomeric region in most species and was highly amplified in the pericentromeric region in some species. StoTR06_159 was either absent or colocalized in the NOR site in some species, and StoIGS_463, which was localized at the NOR site in S. tora, was either absent or localized at the subtelomeric or pericentromeric regions in other species. Conclusions These data suggest that TRs play important roles in S. tora dysploidy and suggest the involvement of 45S rDNA intergenic spacers in “carrying” repeats during genome reshuffling.

scholarly journals The genomic structure of a human chromosome 22 nucleolar organizer region determined by TAR cloning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jung-Hyun Kim ◽  
Vladimir N. Noskov ◽  
Aleksey Y. Ogurtsov ◽  
Ramaiah Nagaraja ◽  
Nikolai Petrov ◽  
...  
Keyword(s):  
Genomic Structure ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Chromosome 21 ◽  
Reference Sequence ◽  
Chromosome 22 ◽  
Rdna Variation ◽  
High Level ◽  
Tar Cloning

AbstractThe rDNA clusters and flanking sequences on human chromosomes 13, 14, 15, 21 and 22 represent large gaps in the current genomic assembly. The organization and the degree of divergence of the human rDNA units within an individual nucleolar organizer region (NOR) are only partially known. To address this lacuna, we previously applied transformation-associated recombination (TAR) cloning to isolate individual rDNA units from chromosome 21. That approach revealed an unexpectedly high level of heterogeneity in human rDNA, raising the possibility of corresponding variations in ribosome dynamics. We have now applied the same strategy to analyze an entire rDNA array end-to-end from a copy of chromosome 22. Sequencing of TAR isolates provided the entire NOR sequence, including proximal and distal junctions that may be involved in nucleolar function. Comparison of the newly sequenced rDNAs to reference sequence for chromosomes 22 and 21 revealed variants that are shared in human rDNA in individuals from different ethnic groups, many of them at high frequency. Analysis infers comparable intra- and inter-individual divergence of rDNA units on the same and different chromosomes, supporting the concerted evolution of rDNA units. The results provide a route to investigate further the role of rDNA variation in nucleolar formation and in the empirical associations of nucleoli with pathology.

Nucleolar organizer region staining patterns in paraffin-embedded tissue cells from human skin cancers

2005 ◽  
Vol 32 (5) ◽  
pp. 323-328 ◽  
Author(s):  
Rosana F. Romao-Correa ◽  
Durvanei A. Maria ◽  
Mithitaka Soma ◽  
Mirian N. Sotto ◽  
Jose Antonio Sanches ◽  
...  
Keyword(s):  
Human Skin ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
Skin Cancers ◽  
Tissue Cells
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