Silver-Staining and Heteromorphism of Chromosomal Nucleolus Organizer Regions in North American Cyprinid Fishes

Copeia ◽  
1984 ◽  
Vol 1984 (1) ◽  
pp. 133 ◽  
Author(s):  
J. R. Gold
Keyword(s):  
North American ◽  
Silver Staining ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Cyprinid Fishes

scholarly journals Silver staining of the nucleolus organizer regions (NOR) requires clusters of sulfhydryl groups.

1982 ◽  
Vol 30 (9) ◽  
pp. 908-911 ◽  
Author(s):  
A De Capoa ◽  
M Ferraro ◽  
P Lavia ◽  
F Pelliccia ◽  
A Finazzi-Agrò
Keyword(s):  
Heavy Metals ◽  
Silver Staining ◽  
Reducing Agents ◽  
Nucleolus Organizer ◽  
The Other ◽  
Nuclear Proteins ◽  
Staining Reaction ◽  
Nucleolus Organizer Regions ◽  
High Affinity ◽  
Per Se

Silver stainability of nucleolus organizer regions (NORs) appears to be correlated with the presence of grouped sulfhydryl (SH) side chains of proteins. In fact, heavy metals with high affinity for SH groups, such as Hg and Cu, do prevent the silver staining reaction. Ferricyanide, which is known to oxidize SH to disulfides, also prevents any further reaction with silver. On the other hand, alkali and reducing agents (mercaptoethanol, cyanide) do not affect silver stainability of the NORs. These results show that the silver staining reaction is not related to disulfide or persulfide groups and that alkali-soluble, acidic nuclear proteins per se do not play a major role in this process.

A simple two-step procedure for silver staining nucleolus organizer regions in plant chromosomes

1985 ◽  
Vol 27 (2) ◽  
pp. 255-257 ◽  
Author(s):  
Romesh C. Mehra ◽  
Susan Brekrus ◽  
Merlin G. Butler
Keyword(s):  
Vicia Faba ◽  
Allium Cepa ◽  
Silver Staining ◽  
Lens Culinaris ◽  
Nucleolar Organizer ◽  
Nucleolus Organizer ◽  
Staining Procedure ◽  
Nucleolar Organizer Regions ◽  
Nucleolus Organizer Regions ◽  
Plant Chromosomes

Nucleolus organizer regions (NORs) of Allium cepa, Lens culinaris, and Vicia faba chromosomes were stained by a two-step silver staining procedure which is simple and highly reproducible. Polymorphisms are apparent with respect to the size of NORs in the taxa understudy.Key words: nucleolar organizer regions, silver staining, Allium cepa, Lens culinaris, Vicia faba.

scholarly journals Karyotype structure and NOR activity in Brazilian Smilax Linnaeus, 1753 species (Smilacaceae)

2019 ◽  
Vol 13 (3) ◽  
pp. 245-263
Author(s):  
Daniel Pizzaia ◽  
Vanessa M. Oliveira-Maekawa ◽  
Aline R. Martins ◽  
Mateus Mondin ◽  
Margarida L. R. Aguiar-Perecin
Keyword(s):  
Silver Staining ◽  
Nucleolus Organizer ◽  
Raw Material ◽  
Chromosome 1 ◽  
Rrna Gene ◽  
Dioecious Species ◽  
Chromosomal Structure ◽  
Nucleolus Organizer Regions ◽  
Karyotype Structure ◽  
Secondary Constrictions

The genus Smilax Linnaeus, 1753 (Smilacaceae) is a large genus of dioecious plants distributed in tropical, subtropical and temperate regions. Some Smilax species have medicinal importance and their identification is important for the control of raw material used in the manufacture of phytotherapeutical products. The karyotypes of seven Brazilian Smilax species were investigated. Mitotic metaphases of roots from young plants were analysed in Feulgen-stained preparations. The karyotypes were asymmetric and modal with 2n = 2x = 32 chromosomes gradually decreasing in size. In S. goyazana A De Candolle & C De Candolle, 1878, a polyploid species, 2n = 4x = 64. In all the species, the large and medium-sized chromosomes were subtelocentric and submetacentric and the small chromosomes were submetacentric or metacentric. Their karyotypes were quite similar, with differences in the arm ratio of some chromosomes. S. fluminensis Steudel, 1841 differed from the other species by having a large metacentric chromosome 1. These findings suggest that evolution occurred without drastic changes in the chromosomal structure in the species analyzed. Terminal secondary constrictions were visualized on the short arm of some chromosomes, but they were detected only in one homologue of each pair. Due to the terminal location and the degree of chromosome condensation, secondary constrictions were not visualized in some species. The nucleolus organizer regions (NORs) were mapped by silver-staining and fluorescent in situ hybridization (FISH) in S. rufescens Grisebach, 1842 and S. fluminensis. Silver-staining and FISH signals were colocalized on the short arms of six chromosomes in S. rufescens and four chromosomes in S. fluminensis. In FISH preparations, one of the largest chromosomes had the secondary constrictions highly decondensed in some cells. This finding and the heteromorphism observed in Feulgen-stained chromosomes suggest that differential rRNA gene expression between homologous rDNA loci can occur in some cells, resulting in different degrees of ribosomal chromatin decondensation. The presence of a heteromorphic chromosome pair in S. rufescens, S. polyantha Grisebach, 1842 and S. goyazana suggests a chromosomal sex determination in these dioecious species.

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