scholarly journals Localización de satélites y cromosomas NOR para la interpretación del cariotipo de Sesbania virgata (Papilionoideae, Sesbanieae) de dos poblaciones americanas

2018 ◽  
Vol 96 (4) ◽  
pp. 619 ◽  
Author(s):  
Fernando Tapia-Pastrana ◽  
Fernando Tapia-Aguirre
Keyword(s):  
Nucleolar Organizer ◽  
Point Of View ◽  
Nucleolar Organizer Regions ◽  
Nucleolar Organization ◽  
Cytogenetic Studies ◽  
Sesbania Virgata ◽  
Satellite Chromosomes ◽  
Secondary Constrictions ◽  
Study Species ◽  
Surface Spreading

<p><strong>Background</strong>: Cytogenetic studies in the genus <em>Sesbania</em> show lack of agreement among the researchers about the precise number and position of secondary constrictions and satellites as well as their relation to the organization of the nucleolus. The lack of this information makes it difficult to carry out reliable comparative cytogenetic studies and chromosome evolution in this genus.</p><p><strong>Questions</strong>: Where are the secondary constrictions and satellites located in the chromosomes of <em>Sesbania</em> <em>virgat</em>a? Do these regions actively participate in the nucleolar organization?</p><p><strong>Study species</strong>: <em>Sesbania virgate</em> (Cav.) Pers.</p><p><strong>Study site</strong>: Municipality of Tlacotalpan, Mexico and Province of Salta, Argentina.</p><p><strong>Methods</strong>: Surface spreading and air-drying technique was applied to obtain chromosomes in prometaphase and typical metaphase from radicular meristems.</p><p><strong>Results</strong>: Each population exhibited a different karyotype and only two secondary constrictions associated with microsatellites in the short arms of the smallest chromosome pair and not in long arms as was suggested by other authors. The inclusion of secondary constrictions and satellites in the nucleolus of cells in prometaphase allowed to corroborate their active participation in the formation of this one. This information was used to reevaluate the position of the nucleolar organizer regions "NOR´s".</p><strong>Conclusions</strong>: Our results agree with the predominant point of view on the location of the "NOR´s" in the short arms of plant species, particularly in legumes. In addition, given that the populations under study are geographically isolated, we suggest that an active process of speciation manifested in the two found cytotypes whose differences are attributed to changes in the proportion of arms of the satellite chromosomes is favored.

A role for upstream binding factor in organizing ribosomal gene chromatin

2006 ◽  
Vol 73 ◽  
pp. 77-84 ◽  
Author(s):  
Jane E. Wright ◽  
Christine Mais ◽  
José-Luis Prieto ◽  
Brian McStay
Keyword(s):  
Nucleolar Organizer ◽  
Ribosomal Gene ◽  
Rna Polymerase I ◽  
Nucleolar Organizer Regions ◽  
Binding Factor ◽  
Upstream Binding Factor ◽  
Acrocentric Chromosomes ◽  
Polymerase I ◽  
Secondary Constrictions ◽  
Active Nors

Human ribosomal genes are located in NORs (nucleolar organizer regions) on the short arms of acrocentric chromosomes. During metaphase, previously active NORs appear as prominent chromosomal features termed secondary constrictions, which are achromatic in chromosome banding and positive in silver staining. The architectural RNA polymerase I transcription factor UBF (upstream binding factor) binds extensively across the ribosomal gene repeat throughout the cell cycle. Evidence that UBF underpins NOR structure is provided by an examination of cell lines in which large arrays of a heterologous UBF binding sequences are integrated at ectopic sites on human chromosomes. These arrays efficiently recruit UBF even to sites outside the nucleolus, and during metaphase form novel silver-stainable secondary constrictions, termed pseudo-NORs, that are morphologically similar to NORs.

Chromosome banding in salmonid fish: nucleolar organizer regions in Salmo and Salvelinus

1985 ◽  
Vol 27 (4) ◽  
pp. 433-440 ◽  
Author(s):  
Ruth Phillips ◽  
Peter E. Ihssen
Keyword(s):  
Atlantic Salmon ◽  
Brown Trout ◽  
Brook Trout ◽  
Chromosome Banding ◽  
Lake Trout ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Banding Patterns ◽  
Single Chromosome ◽  
Secondary Constrictions

Chromosome banding patterns obtained by silver staining (Ag-NORs) were analyzed in three species of Salmo (rainbow, brown trout, and Atlantic salmon) and three species of Salvelinus (brook trout, lake trout, and arctic char). In rainbow trout and Atlantic salmon the Ag-NORs were found at the secondary constrictions of a single chromosome pair, while in brown trout the Ag-NORs were found on the short arms of one or two of the two longest subtelocentric or acrocentric chromosome pairs. The location of the Ag-NORs was multichromosomal in the three Salvelinus species, occurring on one or both members of four to six different chromosome pairs in different individuals. The Ag-NOR sites were on the short arms of some acrocentric pairs and at the telomeres of other acrocentric pairs and one or two metacentric pairs. Chromomycin A3 positive bands were found at the same sites as the Ag-NORs in all species. In the species with multichromosomal location of Ag-NORs, polymorphisms in the size and location of the NORs were extremely common, so that almost every individual fish had a different pattern of Ag-NOR sites.Key words: banding, Salmo, Salvelinus, Ag-NORs, polymorphisms, nucleolar organizer.

NUCLEOLAR ORGANIZER REGIONS IN THE RABBIT (ORYCTOLAGUS CUNICULUS) AS SHOWN BY SILVER STAINING

1978 ◽  
Vol 20 (3) ◽  
pp. 377-382 ◽  
Author(s):  
Patricia A. Martin-Deleon ◽  
Dorene L. Petrosky ◽  
M. Eileen Fleming
Keyword(s):  
New Zealand ◽  
Silver Staining ◽  
Oryctolagus Cuniculus ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Telomeric Region ◽  
Metaphase Chromosomes ◽  
Domestic Rabbit ◽  
Silver Precipitation ◽  
Secondary Constrictions

Nucleolar organizer regions (NOR's) were demonstrated in metaphase chromosomes of the domestic rabbit, Oryctolagus cuniculus (L.) (New Zealand white strain) using silver staining. Sequential quinacrine banding and a modification of the Ag-AS silver precipitation technique with duplicate photography allowed identification of silver staining NOR's on the short arms of chromosomes 13, 16, and 20, as well as the telomeric region of the long arms of number 21 in some cells. Chromosomes 13, 16 and 20 all have subterminal to terminal centromeres, often showed satellites and secondary constrictions, and were sometimes involved in associations.

DIMORPHIC NUCLEOLAR ORGANIZER REGIONS IN THE FROG RANA BLAIRI

1977 ◽  
Vol 19 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Oscar G. Ward
Keyword(s):  
Species Complex ◽  
Rana Pipiens ◽  
Nucleolar Organizer ◽  
Staining Procedure ◽  
Nucleolar Organizer Regions ◽  
Specific Staining ◽  
Rana Blairi ◽  
Ammoniacal Silver ◽  
Secondary Constrictions ◽  
Unequal Length

The nucleolar organizer-specific staining procedure, ammoniacal silver (Ag-AS), has been used to study the distribution and size of the nucleolar organizer regions (NORs) in chromosomes of the frog Rana blairi (Mecham, Littlejohn, Oldham, Brown and Brown). The somatic metaphase karyotype of this frog is similar to that of other frogs of the Rana pipiens species complex, numerically (2n = 26) and morphologically. Secondary constrictions are detectable in untreated Giemsa-stained metaphase preparations as achromatic gaps in the long arms of a pair of submetacentric chromosomes (no. 10). These constrictions are the only regions which are deeply stained with the Ag-AS method and are thus identified as the nucleolar organizer regions (Ag-NORs). In each of the three individuals, the Ag-NORs as visualized on the homologues are of unequal length.

scholarly journals Conserved Cytogenetic Features in the Amazonian Arapaima, Arapaima gigas (Schinz 1822) from Jamari River, Rondônia–Brazil

2009 ◽  
Vol 2 (1) ◽  
pp. 91-94 ◽  
Author(s):  
Renata da Rosa ◽  
Marceléia Rubert ◽  
Mauro Caetano-Filho ◽  
Lucia Giuliano-Caetano
Keyword(s):  
Diploid Number ◽  
Nucleolar Organizer ◽  
Pericentromeric Region ◽  
Nucleolar Organizer Regions ◽  
Fluorochrome Staining ◽  
Arapaima Gigas ◽  
Chromosomal Pair ◽  
Silver Nitrate Staining ◽  
Subterminal Region ◽  
Secondary Constrictions

Specimens of Arapaima gigas from Jamari River (RO) were cytogenetically analyzed. A diploid number of 2n=56 chromosomes was found (28m-sm + 28st-a). Secondary constrictions were observed on the short arms of chromosome 3. Nucleolar Organizer Regions (NORs) were detected at the subterminal region on short arms of the third chromosomal pair by both silver nitrate staining and FISH with 45S rDNA probe, being equivalent to secondary constrictions. The ribosomal sites were also characterized by size heteromorphism and presence of CMA3+/DAPI- blocks. The constitutive heterochromatin was located at pericentromeric region of some chromosomes. After sequential Cbanding and base-specific fluorochromes staining, most of the heterochromatins proved to be neutral, i.e., with similar amounts of AT and GC bases. Nonetheless, some heterochromatic regions were marked by GC-specific fluorochromes in one chromosomal pair and by AT-specific fluorochrome staining on two pairs. The present data are in agreement with previous reports in populations from Araguaya River, indicating that conserved cytogenetic features are present in this important fish species.

Cytotaxonomic studies of Encarsia Förster (Hymenoptera: Aphelinidae)

1999 ◽  
Vol 89 (3) ◽  
pp. 209-215 ◽  
Author(s):  
F. Baldanza ◽  
L. Gaudio ◽  
G. Viggiani
Keyword(s):  
Chromosome Number ◽  
Cryptic Species ◽  
Silver Staining ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Economic Interest ◽  
C Banding ◽  
Cytogenetic Studies ◽  
Karyological Data ◽  
Karyotype Differentiation

AbstractA cytotaxonomic study was carried out on 13 species of Encarsia Förster, known to parasitize aleyrodids and diaspidids. The chromosomes varied greatly both in number and morphology, with E. protransvena Viggiani having the lowest chromosome number (2n = 6) and E. asterobemisiae Viggiani & Mazzone the highest (2n = 20). The most common chromosome number was 2n = 10. C-banding, G-banding and silver staining for nucleolar organizer regions (NOR) provided the possibility of distinguishing between karyotypes with the same chromosome number and morphology and to identify all the pairs of homologues in a diploid set for advanced cytogenetic studies. The karyotype of Coccophagus lycimnia (Walker) was also examined. The chromosome data suggested that in Encarsia, karyotype differentiation has mainly occurred through a series of centric fusions, although other rearrangements may also have been significant. The importance of karyological data in systematic studies and in the identification of biotypes and cryptic species of economic interest is outlined.

Biological aspects of Amazonian fishes. IX. Cytogenetic studies in two species of the genus Semaprochilodus (Pisces, Prochilodontidae)

Genome ◽  
1987 ◽  
Vol 29 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Eliana Feldberg ◽  
Luiz Antonio Carlos Bertollo ◽  
Lurdes Foresti de Almeida Toledo ◽  
Fausto Foresti ◽  
Orlando Moreira Filho ◽  
...  
Keyword(s):  
Diploid Number ◽  
Constitutive Heterochromatin ◽  
Low Frequency ◽  
Nucleolar Organizer ◽  
Hybrid Origin ◽  
Nucleolar Organizer Regions ◽  
Nucleolar Organizing Regions ◽  
Cytogenetic Studies ◽  
Key Words Fish ◽  
Biological Aspects

The karyotype of Semaprochilodus insignis and Semaprochilodus taeniurus were analyzed through the conventional Giemsa staining, C-banding, and the nucleolar organizer regions. The diploid number is the same (2n = 54) in both species, but S. taeniurus shows a chromosomic system of the ZZ/ZW type. This and some other differences between the two karyotypes will be useful in further studies on the possible hybrid origin of the "jaraqui açú," a low frequency form that is observed together with S. insignis and S. taeniurus. Key words: fish, ZZ/ZW system, constitutive heterochromatin, nucleolar organizing regions.

Electron Microscopic investigation of crooke’s change in the pituitaries of patients with hypercorticism

1989 ◽  
Vol 47 ◽  
pp. 848-849
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
L. Stefaneanu ◽  
N. Losinski
Keyword(s):  
Nucleolar Organizer ◽  
Microscopic Investigation ◽  
Electron Microscopic Investigation ◽  
Ectopic Acth Syndrome ◽  
Nucleolar Organizer Regions ◽  
Electron Microscopic ◽  
Human Pituitary ◽  
Ectopic Acth ◽  
Crooke’S Hyalinization

Human pituitary corticotropins have unique morphologic markers: bundles of type-1 filaments, measuring approximately 70 A in width and representing cytokeratin. The extreme ring-like accumulation of type-1 filaments, known as Crooke's hyalinization, signals functional suppression of the corticotropins and occurs in endogenous and exogenous glucocorticoid excess, caused by ACTH-secreting pituitary adenoma, glucocorticoid secreting adrenocortical tumor, ectopic ACTH-syndrome and administration of pharmacologic doses of glucocorticoids. Cells of autonomous corticotroph adenomas usually do not show Crooke's hyalin change. A minority of these tumors, however, retains sensitivity to the negative feed-back effect of elevated blood glucocorticoid levels and display typical Crooke’s change.In the present study pituitary corticotropins in various phases of Crooke's hyalinization were investigated in patients with glucocorticoid excess of various origin, applying histology, immunocytochemistry, count of argyrophilic nucleolar organizer regions (AgNOR), and transmission electron microscopy.

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.

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