Variation of nuclear ribosomal RNA genes in Eragrostis tef (Zucc.) Trotter

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 815-821 ◽  
Author(s):  
Michael Pillay
Keyword(s):  
Ribosomal Rna ◽  
Restriction Site ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Eragrostis Tef ◽  
Length Variation ◽  
Rdna Repeat ◽  
Spacer Length ◽  
Repeat Units ◽  
Rna Genes

Variation in the ribosomal RNA genes (rDNA) was examined to assess the genetic variability among 314 plants representing 28 accessions of Eragrostis tef, an important food crop. A restriction site map was constructed for the species by localization of the BamHI, BglII, DraI, EcoRI, EcoRV, NdeI, SacI, SpeI, XbaI, and XhoI sites. A comparison of this map with those of other grasses showed conservation of sites, especially in the coding region. However, a unique EcoRI site combined with a BamHI site in the 18S region may be of diagnostic value for the species. A BamHI fragment that spans the intergenic spacer was used as an indicator of length variation of rDNA repeat units. rDNA repeat units in E. tef ranged in size from 8.4 to 11.07 kbp. Considerable size variation of rDNA repeats was present among accessions, between individual plants within some accessions, and within single plants. A total of 19 spacer length (sl) phenotypes was observed in 16 accessions in which 11–42 plants were analyzed. A single restriction site polymorphism was detected in PI442115 that was also distinguished by having a single sl variant. Variation in the rRNA genes is a useful indicator of genetic diversity in E. tef germplasm.Key words: Eragrostis tef, ribosomal DNA, restriction map, genetic variation.

5S ribosomal RNA genes in six species of Mediterranean grey mullets: genomic organization and phylogenetic inference

Genome ◽  
2007 ◽  
Vol 50 (9) ◽  
pp. 787-795 ◽  
Author(s):  
Ekaterina Gornung ◽  
Paolo Colangelo ◽  
Flavia Annesi
Keyword(s):  
Ribosomal Rna ◽  
Blot Hybridization ◽  
5S Rdna ◽  
Ribosomal Rna Genes ◽  
Rdna Repeat ◽  
Data Set ◽  
Single Chromosome ◽  
5S Ribosomal Rna ◽  
Repeat Units ◽  
Rna Genes

This paper describes a study of the 5S ribosomal RNA genes (5S rDNA) in a group of 6 species belonging to 4 genera of Mugilidae. In these 6 species, the relatively short 5S rDNA repeat units, generated by PCR and ranging in size from 219 to 257 bp, show a high level of intragenomic homogeneity of both coding and spacer regions (NTS-I). Phylogenetic reconstructions based on this data set highlight the greater phylogenetic and genetic diversity of Mugil cephalus and Oedalechilus labeo compared with the genera Liza and Chelon. Comparative sequence analysis revealed significant conservation of the short 5S rDNA repeat units across Chelon and Liza. Moreover, a second size class of 5S rDNA repeat units, ranging from roughly 800 to 1100 bp, was produced in the Liza and Chelon samples. Only short 5S rDNA repeat units were found in M. cephalus and O. labeo. The sequences of the long 5S rDNA repeat units, obtained in Chelon labrosus and Liza ramada , differ owing to the presence of 2 large insertion/deletions (indels) in the spacers (NTS-II) and show considerable sequence identity with NTS-I spacers. Interspecific sequence variation of NTS-II spacers, excluding the indels, is low. Southern-blot hybridization patterns suggest an intermixed arrangement of short and long repeat units within a single chromosome locus.

Basonuclin is associated with the ribosomal RNA genes on human keratinocyte mitotic chromosomes

1999 ◽  
Vol 112 (18) ◽  
pp. 3039-3047 ◽  
Author(s):  
H. Tseng ◽  
J.A. Biegel ◽  
R.S. Brown
Keyword(s):  
Ribosomal Rna ◽  
Zinc Fingers ◽  
Hair Follicles ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Control Element ◽  
Rrna Gene ◽  
Metaphase Chromosomes ◽  
Acrocentric Chromosomes ◽  
Rna Genes

Basonuclin is a zinc finger protein mainly expressed in keratinocytes of the basal layer of epidermis and the outer root sheath of hair follicles. It is also found in abundance in the germ cells of testis and ovary. In cultured keratinocytes, basonuclin is associated with chromatin in all phases of the cell cycle, including mitosis. By immunocytochemical methods, we demonstrate here that in mitosis basonuclin is associated with the short arms of the acrocentric chromosomes and with other loci on many metaphase chromosomes of human keratinocytes. Using the evolutionarily highly conserved N-terminal pair of zinc fingers in an electrophoresis mobility shift assay, we demonstrate that the DNA target sequences of basonuclin on the acrocentric chromosomes are likely to be within the promoter region of the 45S rRNA gene transcription unit. DNase I footprinting shows that basonuclin zinc fingers interact with the upstream control element of this promoter, which is necessary for the high level of transcription of the rRNA genes. This result suggests that basonuclin may be a tissue-specific transcription factor for the ribosomal RNA genes.

Length and sequence heterogeneity in 5S rDNA of Populus deltoides

Genome ◽  
2002 ◽  
Vol 45 (6) ◽  
pp. 1181-1188 ◽  
Author(s):  
Madan S Negi ◽  
Jyothi Rajagopal ◽  
Neeti Chauhan ◽  
Richard Cronn ◽  
Malathi Lakshmikumaran
Keyword(s):  
Populus Deltoides ◽  
5S Rdna ◽  
Rrna Genes ◽  
Length Variation ◽  
Spacer Length ◽  
Sequence Heterogeneity ◽  
Distance Analysis ◽  
Repeat Units ◽  
Class 1 ◽  
Dna Microsatellite

The 5S rRNA genes and their associated non-transcribed spacer (NTS) regions are present as repeat units arranged in tandem arrays in plant genomes. Length heterogeneity in 5S rDNA repeats was previously identified in Populus deltoides and was also observed in the present study. Primers were designed to amplify the 5S rDNA NTS variants from the P. deltoides genome. The PCR-amplified products from the two accessions of P. deltoides (G3 and G48) suggested the presence of length heterogeneity of 5S rDNA units within and among accessions, and the size of the spacers ranged from 385 to 434 bp. Sequence analysis of the non-transcribed spacer (NTS) revealed two distinct classes of 5S rDNA within both accessions: class 1, which contained GAA trinucleotide microsatellite repeats, and class 2, which lacked the repeats. The class 1 spacer shows length variation owing to the microsatellite, with two clones exhibiting 10 GAA repeat units and one clone exhibiting 16 such repeat units. However, distance analysis shows that class 1 spacer sequences are highly similar inter se, yielding nucleotide diversity (π) estimates that are less than 0.15% of those obtained for class 2 spacers (π = 0.0183 vs. 0.1433, respectively). The presence of microsatellite in the NTS region leading to variation in spacer length is reported and discussed for the first time in P. deltoides.Key words: 5S rDNA, Populus, repetitive DNA, microsatellite, sequence heterogeneity.

Detection of ribosomal RNA genes in soybean, Glycine max (L.) Merr., by in situ hybridization

Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1091-1095 ◽  
Author(s):  
Halina Skorupska ◽  
Marc C. Albertsen ◽  
Kim D. Langholz ◽  
Reid G. Palmer
Keyword(s):  
In Situ Hybridization ◽  
Glycine Max ◽  
Ribosomal Rna ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Single Pair ◽  
Glycine Max L ◽  
Labeled Probe ◽  
Rna Genes

A biotinylated maize rRNA probe was hybridized to soybean nuclei. Hybridization was detected by using a streptavidin horseradish peroxidase biotin system. The procedure used enabled detection of heterologous complementary 18S and 25S rRNA coding genes in soybean. In diploid cultivars 'Hark' and 'Lincoln' a single pair of satellited chromosomes was present and two binding sites were detected at interphase. In plants trisomic for the satellited chromosome, three sites were observed, and in tetraploid nuclei, four sites were seen. The in situ hybridization results indicated that, for ribosomal RNA genes, Glycine max behaves as a diploid. We discuss the possibility of loss of a pair of satellited chromosomes in the evolution of soybean.Key words: biotin-labeled probe, rRNA genes, ploidy, Glycine max.

scholarly journals Exchange between the ribosomal RNA genes of X and Y chromosomes in Drosophila melanogaster males

1981 ◽  
Vol 38 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. H. Maddern
Keyword(s):  
Drosophila Melanogaster ◽  
Ribosomal Rna ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Y Chromosomes ◽  
A Site ◽  
Rna Genes ◽  
Uniform Polarity

SUMMARYThe genes coding for the 18s and 28s ribosomal RNA (rRNA) are present on both the X and Y chromosomes of D. melanogaster at a site known as the bobbed locus. Exchange was observed in males between a normally orientated X and Y chromosome (Dp(1; 1) scv1 and BSY y31d) with a frequency of 0·079%. One-quarter (7 in 27) of these exchange products between two + chromosomes which both carried sufficient rRNA genes for a bb+ phenotype exhibited a bb phenotype. Evidence is presented that one-half, and possibly all, of the exchanges involved the repetitive bb genes. These results together with those reported by Palumbo, Caizzi & Ritossa (1973) imply that the repeated bb genes of either (or both) the X or Y chromosome are not arranged with uniform polarity and, further, that spermatogonial exchange between the X and Y chromosomes may be restricted to the bb loci.

Ribosomal RNA genes and the substructure of nucleolar organizing regions in Lilium

1984 ◽  
Vol 26 (2) ◽  
pp. 158-166 ◽  
Author(s):  
L. von Kalm ◽  
D. R. Smyth
Keyword(s):  
In Situ Hybridization ◽  
Ribosomal Rna ◽  
Relative Size ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Gene Number ◽  
Nucleolar Organizing Regions ◽  
Band Size ◽  
Rna Genes

We have examined the location and organization of nucleolar organizing regions (NORs) in the species Lilium henryi (with four NORs per diploid cell), L. longiflorum, and L. speciosum (each with six NORs), and the hybrids Lilium × 'Black Beauty' (five NORs) and Lilium × parkmannii (eight NORs). The relative number of genes in individual NORs was assayed by in situ hybridization using in vitro labelled ribosomal RNA (rRNA). An estimate of their relative transcriptional activity was obtained by scoring silver band size over the constriction. There was no clear correlation between gene number and activity at specific NORs. Rather, gene number correlated quite well with the relative size of heterochromatin usually found adjacent to NOR constrictions and stained by an acid-banding method. It is possible that many but a variable fraction of the rRNA genes in Lilium NORs are held inactive in nucleolar heterochromatin.Key words: ribosomal RNA genes, Lilium, nucleolus, in situ hybridization, heterochromatin, silver banding.

scholarly journals The structure of the yeast ribosomal RNA genes. 3. Precise mapping of the 18 S and 25 S rRNA genes and structure of the adjacent regions

1981 ◽  
Vol 9 (4) ◽  
pp. 789-799 ◽  
Author(s):  
A.A. Bayev ◽  
O.I. Georgiev ◽  
A.A. Hadjiolov ◽  
N. Nikolaev ◽  
K.G. Skryabin ◽  
...  
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Precise Mapping ◽  
Rna Genes

scholarly journals A GENETIC LOCUS HAVING TRANS AND CONTIGUOUS CIS FUNCTIONS THAT CONTROL THE DISPROPORTIONATE REPLICATION OF RIBOSOMAL RNA GENES IN DROSOPHILA MELANOGASTER

Genetics ◽  
1978 ◽  
Vol 88 (1) ◽  
pp. 67-79
Author(s):  
James D Procunier ◽  
Kenneth D Tartof
Keyword(s):  
Ribosomal Rna ◽  
Germ Line ◽  
Genetic Locus ◽  
Position Effect ◽  
Ribosomal Rna Genes ◽  
Rrna Genes ◽  
Position Effect Variegation ◽  
Compensatory Response ◽  
Cis Acting ◽  
Rna Genes

ABSTRACT The results of deficiency mapping experiments reveal the presence of a compensatory response (c r +) locus that is located distal to the cluster of ribosomal RNA (rRNA) genes and is responsible for disproportionately replicating these genes when cr+ locus is present in a single dose, as in X/O males or X / SC4 - Sc8 females. The cr+ locus is novel in that it exhibits both trans and contiguous cis acting properties in somatic cells. It acts in trans to detect the presence of its partner locus in the opposite homolog, and if that partner locus is absent, it acts in cis to drive the disproportionate replication of those rRNA genes (rDNA) that are contiguous with it. The ability of cr+ to function is independent of the number of ribosomal RNA genes present. Furthermore, it can be shown that the cr+ locus is not required for the magnification or reduction of germ line rDNA. Finally, the implications of cr+ for position-effect variegation and the apparent reversion of the abnormal oocyte (abo) phenotype are discussed.

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