Nucleolar organizer activity at meiosis in wheat–rye hybrid plants

1986 ◽  
Vol 28 (2) ◽  
pp. 227-234 ◽  
Author(s):  
N. Cuñado ◽  
M. C. Cermeño ◽  
J. Orellana
Keyword(s):  
Silver Staining ◽  
Staining Method ◽  
Nucleolar Organizer ◽  
The Other ◽  
Nucleolar Organizer Regions ◽  
Binucleate Cells ◽  
Hybrid Plants ◽  
Nucleolar Organizer Activity ◽  
Silver Staining Method ◽  
Organizer Activity

Nucleoli and nucleolar organizer regions (NORs) have been studied by a silver staining method in all meiotic stages of wheat–rye hybrid plants. The maximum number of nucleoli per cell scored at meiotic prophase and tapetum binucleate cells indicates that only the NORs of 1B, 6B, and 5D wheat chromosomes are active, whereas that of chromosome IR (SAT) of rye is inactive. However, at diakinesis, metaphase and anaphase meiotic stages only chromosomes 1B and 6B show Ag-NOR as was reported previously in somatic metaphase. The absence of Ag-NOR on chromosome 5D has been imputed to its low nucleolar organizer activity, not detectable by silver staining, because of the small number of rDNA clusters it carries. On the other hand, the meiotic behaviour of chromosomes 1B and 6B has been studied at metaphase I and anaphase I, using the Ag-NORs as cytological markers.Key words: nucleolar organizer, Ag-NOR, meiosis, wheat–rye hybrids.

Silver staining method for nucleolar organizer regions in cervical smears

1997 ◽  
Vol 16 (6) ◽  
pp. 497-499 ◽  
Author(s):  
Edenilson Eduardo Calore ◽  
Neuza Kasumi Shirata ◽  
Lai Wun Song Shih ◽  
Maria José Cavaliere ◽  
Marília de Siqueira
Keyword(s):  
Silver Staining ◽  
Staining Method ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Cervical Smears ◽  
Silver Staining Method

Nucleolar organizer activity in wheat, rye and derivatives analyzed by a silver-staining procedure

Chromosoma ◽  
1984 ◽  
Vol 89 (5) ◽  
pp. 370-376 ◽  
Author(s):  
M. C. Cerme�o ◽  
J. Orellana ◽  
J. L. Santos ◽  
J. R. Lacadena
Keyword(s):  
Silver Staining ◽  
Nucleolar Organizer ◽  
Staining Procedure ◽  
Nucleolar Organizer Activity ◽  
Organizer Activity

Diagnostic importance of the nucleolar organizer regions in Wegener's granulomatosis

1997 ◽  
Vol 111 (9) ◽  
pp. 825-828
Author(s):  
Wen L. Yue ◽  
Zheng Z. Ma ◽  
Zhi H. Sun
Keyword(s):  
Silver Staining ◽  
Wegener’S Granulomatosis ◽  
Inflammatory Lesion ◽  
Nucleolar Organizer ◽  
Wegener's Granulomatosis ◽  
Nucleolar Organizer Regions ◽  
Significant Difference ◽  
Silver Staining Method ◽  
Malignant Reticulosis ◽  
The Difference

AbstractThe number and distribution pattern of silver staining nucleolar organizer regions (AgNORs) were thought to reflect the cellular proliferative activity and the malignancy of tumours. Using a silver-staining method, the variations of AgNORs have been studied in patients with atypical inflammatory lesion (n = 5), malignant reticulosis (n = 5) and Wegener's granulomatosis (n = 6). Our results reveal that there was a statistically significant difference (p<0.01), highly suggestive of a difference in AgNOR counts between the atypical inflammatory lesion and Wegener's granulomatosis, with the Wegener's granulomatosis specimens having the higher irregular AgNORs, but the difference between Wegener's granulomatosis and malignant reticulosis is probably not clinically important. It is concluded that AgNORs may be useful in differentiating Wegener's granulomatosis from an atypical inflammatory lesion, and the simplified counting technique is adequate for the purpose.

Nucleolar organizer competition in Aegilops–rye hybrids

1985 ◽  
Vol 27 (4) ◽  
pp. 479-483 ◽  
Author(s):  
M. C. Cermeño ◽  
J. R. Lacadena
Keyword(s):  
Secale Cereale ◽  
Silver Staining ◽  
Nucleolar Organizer ◽  
Nucleolus Organizer ◽  
Staining Procedure ◽  
Nucleolar Activity ◽  
Nucleolar Organizer Activity ◽  
Organizer Activity ◽  
Chromosome 1R

The nucleolar organizer activity in several Aegilops × rye hybrids (A. triuncialis × Secale cereale, A. variabilis × S. cereale, A. biunicialis × S. cereale, A. biuncialis × S. vavilovii, A. juvenalis × S. cereale) is analyzed by using a highly reproducible silver-staining procedure. The 1U and 5U chromosomes show a strong nucleolar activity, suppressing the NOR activity of chromosome 1R from rye in all the hybrid combinations (UCR, USvR, UMbR, UMbRv, and UMjDR). The nucleolus organizer chromosomes from the genomes C, Sv, Mb, and Mj show small activities. Our results confirm previous data of the nucleolar organizer activity predominant status of the 1U and 5U chromosomes from the U genome (A. umbellulata) and the weakest condition of the 1R chromosome from rye. A diagram showing the relationships between the nucleolar organizer activities of chromosomes from different genomes of Triticeae is presented.Key words: nucleolar competition, amphiplasty, Ag-NORs, Triticeae, Aegilops, Secale.

Sequential silver staining and in situ hybridization reveal a direct association between rDNA levels and the expression of homologous nucleolar organizing regions: a hypothesis for NOR structure and function

1998 ◽  
Vol 111 (10) ◽  
pp. 1433-1439
Author(s):  
F. Zurita ◽  
R. Jimenez ◽  
M. Burgos ◽  
R.D. de la Guardia
Keyword(s):  
Transcription Factors ◽  
In Situ Hybridization ◽  
Silver Staining ◽  
Organizer Region ◽  
Nucleolar Organizer ◽  
Interindividual Variation ◽  
Nucleolar Organizer Regions ◽  
Single Pair ◽  
Ribosomal Cistrons

We have developed a procedure for sequential silver staining and in situ hybridization to analyze the relationship between the amount of rDNA present in nucleolar organizer regions, as estimated by in situ hybridization, and their level of expression, as estimated by the silver signal. For simplicity we used cells from the insectivorous mole Talpa occidentalis, which have a single pair of nucleolar organizer regions in chromosome pair 3. The relative content of ribosomal cistrons was also related to the hierarchy of activation of the nucleolar organizer regions present in this chromosomal pair. Statistical analyses demonstrated that both the relative level of expression and the activation hierarchy depended mainly on the number of ribosomal cistrons in nucleolar organizer regions. We propose a functional two-step hypothesis, which is consistent with most known data concerning interchromosomal, intercellular and interindividual variation in a number of plant and animal species, including Talpa occidentalis. In step one, the first available transcription factors bind randomly to the ribosomal promoters, such that larger nucleolar organizer regions are more likely to recruit them. In the second step the remaining transcription factors are recruited in a cooperative way, thus completing activation of one nucleolar organizer region, before the next one becomes active.

Variation in rDNA Redundancy Level and Nucleolar Organizer Length in Normal and Variant Lines of the Mexican Axolotl

1974 ◽  
Vol 15 (2) ◽  
pp. 239-257
Author(s):  
J. H. SINCLAIR ◽  
CAROLE R. CARROLL ◽  
R. R. HUMPHREY
Keyword(s):  
Genetic Material ◽  
Nucleolar Organizer ◽  
Ambystoma Mexicanum ◽  
The Other ◽  
Colour Pattern ◽  
Nucleolar Organizer Regions ◽  
Wild Type ◽  
Mexican Axolotl ◽  
Apparent Lack ◽  
Heterozygous Condition

The level of redundancy of ribosomal genes, and the relationship of this level to nucleolar formation at different stages of embryonic development, have been examined in the Mexican axolotl, Ambystoma mexicanum. Individuals from 4 inbred stocks were examined, as well as descendants from 2 nucleolar variants which, in the heterozygous condition, are distinguished by exceptionally small nucleoli. Ribosomal RNA-DNA hybridization assays show that one of the 4 wild type lines has only about one-third as much ribosomal DNA (rDNA) as the other three. One of the nucleolar variants has the same level of rDNA as the larger wild-type level; the other variant has the same amount as the smaller ribosomal genome line. Both original nucleolar variants arose as F1 progeny of crosses between a large rDNA genome line and the small genome line. Cytological examination of pregastrula stage embryos from wild type and nucleolar variant lines show that the lengths of the nucleolar organizer regions (NOR) and the sizes of nucleoli formed, are directly correlated with the amount of rDNA present at the nucleolar locus. During gastrulation of the nucleolar variants, however, a transition appears to take place and the amount of rDNA ceases to be the determining factor in nucleolar size. After late gastrula, heterozygous progeny resulting from crosses of either large rDNA genome or small rDNA genome wild type individuals with either nucleolar variant line, have a small and a large nucleolus. The factor or factors associated with this apparent lack of competitive ability of the variant NOR, when opposed to a normal NOR, are unknown. It might be suggested that since the chromosomal alterations which produced the nucleolar variants in both cases eliminated the gene determining the dark colour pattern, they could at the same time have eliminated other genetic material.

The Hordeum bulbosum 25S-18S rDNA region: comparison with Hordeum vulgare and other Triticeae

2019 ◽  
Vol 74 (11-12) ◽  
pp. 319-328
Author(s):  
Oleg Georgiev ◽  
Kiril Mishev ◽  
Maria Krasnikova ◽  
Meglena Kitanova ◽  
Anna Dimitrova ◽  
...  
Keyword(s):  
Hordeum Vulgare ◽  
18S Rdna ◽  
Intergenic Spacer ◽  
Nucleolar Organizer ◽  
The Other ◽  
Nucleolar Organizer Regions ◽  
Hordeum Bulbosum ◽  
Promoter Sequences ◽  
External Transcribed Spacer

Abstract Hordeum vulgare and Hordeum bulbosum are two closely related barley species, which share a common H genome. H. vulgare has two nucleolar organizer regions (NORs), while the NOR of H. bulbosum is only one. We sequenced the 2.5 kb 25S-18S region in the rDNA of H. bulbosum and compared it to the same region in H. vulgare as well as to the other Triticeae. The region includes an intergenic spacer (IGS) with a number of subrepeats, a promoter, and an external transcribed spacer (5′ETS). The IGS of H. bulbosum downstream of 25S rRNA contains two 143-bp repeats and six 128-bp repeats. In contrast, the IGS in H. vulgare contains an array of seven 79-bp repeats and a varying number of 135-bp repeats. The 135-bp repeats in H. vulgare and the 128-bp repeats in H. bulbosum show similarity. Compared to H. vulgare, the 5′ETS of H. bulbosum is shorter. Additionally, the 5′ETS regions in H. bulbosum and H. vulgare diverged faster than in other Triticeae genera. Alignment of the Triticeae promoter sequences suggests that in Hordeum, as in diploid Triticum, transcription starts with guanine and not with adenine as it is in many other plants.

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