Suppression of human nucleolus organizer activity in mouse-human somatic hybrid cells

Miller, Dorothy A.; Dev, V.G.; Tantravahi, Ramana; Miller, Orlando J.

doi:10.1016/0014-4827(76)90373-6

Cited by 431 publications

(144 citation statements)

References 22 publications

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“…The presence of CMA 3 positive marks in the terminal region of two other chromosomes of N. cruentata would be related to the inactive NORs, considering that these regions were not evidenced by the silver nitrate impregnation, which marks only active NORs in the preceding interphasis according to Miller et al (1976), Howell (1977) and Schwarzacher et al (1978), or would represent a special kind of chromatin, rich in GC bases, but not evidenced by the C-banding technique employed in the present study.…”

Section: Discussionmentioning

confidence: 63%

Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

2005

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The aim of this work is to characterize Nephilengys cruentata in relation to the diploid number, chromosome morphology, type of sex determination chromosome system, chromosomes bearing the Nucleolar Organizer Regions (NORs), C-banding pattern, and AT or GC repetitive sequences. The chromosome preparations were submitted to standard staining (Giemsa), NOR silver impregnation, C-banding technique, and base-specific fluorochrome staining. The analysis of the cells showed 2n = 24 and 2n = 26 chromosomes in the embryos, and 2n = 26 in the ovarian cells, being all the chromosomes acrocentric. The long arm of the pairs 1, 2 and 3 showed an extensive negative heteropycnotic area when the mitotic metaphases were stained with Giemsa. The sexual chromosomes did not show differential characteristics that allowed to distinguish them from the other chromosomes of the complement. Considering the diploid numbers found in N. cruentata and the prevalence of X 1 X 2 sex determination chromosome system in Tetragnathidae, N. cruentata seems to possess 2n = 24 = 22 + X 1 X 2 in the males, and 2n = 26 = 22 + X 1 X 1 X 2 X 2 in the females. The pairs 1, 2 and 3 showed NORs which are coincident with the negative heteropycnotic patterns. Using the C-banding technique, the pericentromeric region of the chromosomes revealed small quantity or even absence of constitutive heterochromatin, differing of the C-banding pattern described in other species of spiders. In N. cruentata the fluorochromes DAPI/ DA, DAPI/MM and CMA 3 /DA revealed that the constitutive heterochromatin is rich in AT bases and the NORs possess repetitive sequences of GC bases.Key words: chromosome, Araneae, heterochromatin, secondary constriction, Chromomycin A 3 . RESUMOAnálise citogenética da aranha neotropical Nephilengys cruentata (Araneomorphae, Tetragnathidae): coloração convencional, RONs, bandas C e fluorocromos base-específicos O objetivo deste trabalho é caracterizar Nephilengys cruentata em relação ao número diplóide, à morfologia cromossômica, ao tipo de sistema cromossômico de determinação sexual, aos cromossomos portadores de Regiões Organizadoras de Nucléolo (RONs), padrão de bandas C e seqüências AT ou GC repetitivas. As preparações cromossômicas foram submetidas à coloração convencional (Giemsa), à impregnação pelo nitrato de prata, técnica de obtenção de bandas C e à coloração com fluorocromos base-específicos. A análise das células mostrou 2n = 24 e 2n = 26 cromossomos nos embriões e 2n = 26 nas células ovarianas, sendo todos cromossomos acrocêntricos. O braço longo dos pares 1, 2 e 3 apresentou extensa região heteropicnótica negativa quando as metáfases mitóticas foram coradas com Giemsa. Os cromossomos sexuais Braz. J. Biol., 65(2): 193-202, 2005 194 ARAÚJO, D., CELLA, D. M. and BRESCOVIT, A. D.species possess the type X 1 X 2 X 3 X 4 /X 1 X 1 X 2 X 2 X 3 X 3 X 4 X 4 (Datta & Chatterjee, 1983), 5 species possess the type X 1 X 2 X 3 Y/X 1 X 1 X 2 X 2 X 3 X 3 (Maddison, 1982) and 2 species show the type X 1 X 2 Y/X 1 X 1 X 2 X 2 (Silva, 1988...

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Section: Discussionmentioning

confidence: 63%

Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

2005

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“…These observations were further substantiated by results obtained by silver impregnation (AgNO1-NOR-staining). The histochemical silver staining method is indicative of the transcriptional activity of rDNA (Miller et a!., 1976). Ag-positive segments were observed at the secondary constriction of both nucleolar chromosomes No.…”

Section: Resultsmentioning

confidence: 99%

Ribosomal RNA genes in B chromosomes of Crepis capillaris detected by non-radioactive in situ hybridization

Małuszyńska

Schweizer

1989

Heredity

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A non-radioactive in Situ hybridization method using biotin-labelled rDNA has made it possible to localize rRNA genes not only at the secondary constriction in both homologous chromosomes No. 3 of Crepis capillaris but also in the B chromosomes occurring in the plants employed. Very clear dot-like rDNA signals at the telomeres of both arms were observed in all B chromosomes. Histochemical silver staining, which is indicative of transcriptional activity of rRNA gene clusters, resulted in both darkly-staining nucleolar constrictions of chromosomes No. 3 and silver deposits at the telomeres of Bs. We conclude that the B chromosomes of C. capillaris are isochromosomes with active rRNA genes located near both telomeres.

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“…)V-bands (Tantravahi et al, 1976). If we instead accept that the secondary constriction is the constant index of the activity of the nucleolus organiser, from our data we can deduce that the presence of N-bands in Asellus is not related to the function.…”

Section: Resultsmentioning

confidence: 49%

“…For this second technique the hypothesis was put forth that the nucleolus organiser staining is linked to the capacity of the rRNA genes of being transcribed (Tantravahi et al, 1976;Miller et at., 1976 fig. 7) two pairs of chromosomes with a subterminal secondary constriction and therefore satellites can be observed.…”

Section: Introductionmentioning

confidence: 99%

N-banding and nucleolus organisers in Asellus aquaticus (crust. isop.)

et al. 1977

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SUMMARYThe N-banding technique was used to stain the nucleolus organiser of the karyotype of Asellus aquaticus (Crust. Isop.). Observations were made on the morphological expression of nucleolus organisers as secondary constrictions and the presence of nucleoli in mitotic prophase. An attempt was made to correlate the various results and it seems likely that N-banding is not a reflection of NO activity.

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Suppression of human nucleolus organizer activity in mouse-human somatic hybrid cells

Cited by 431 publications

References 22 publications

Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

Cytogenetic analysis of the neotropical spider Nephilengys cruentata (Araneomorphae, tetragnathidae): standard staining, NORs, C-bands and base-specific fluorochromes

Ribosomal RNA genes in B chromosomes of Crepis capillaris detected by non-radioactive in situ hybridization

N-banding and nucleolus organisers in Asellus aquaticus (crust. isop.)

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