Structural correspondence between nucleolus- and sphere-organizing regions of the lampbrush chromosomes and secondary constrictions of the mitotic chromosomes

1972 ◽  
Vol 28 (5) ◽  
pp. 586-588 ◽  
Author(s):  
G. Mancino ◽  
Irma Nardi ◽  
Matilde Ragghianti
Keyword(s):  
Lampbrush Chromosomes ◽  
Mitotic Chromosomes ◽  
Structural Correspondence ◽  
Secondary Constrictions

scholarly journals Chromosomes and Nucleoli of the Axolotl, Ambystoma Mexicanum

1966 ◽  
Vol 1 (1) ◽  
pp. 85-108
Author(s):  
H. G. CALLAN
Keyword(s):  
Low Temperature ◽  
Nuclear Periphery ◽  
Great Majority ◽  
Lampbrush Chromosome ◽  
Ambystoma Mexicanum ◽  
Oocyte Nucleus ◽  
Lampbrush Chromosomes ◽  
Mitotic Chromosomes ◽  
Nucleolar Material ◽  
Secondary Constrictions

Amongst the axolotl's haploid complement of fourteen mitotic chromosomes, one of the four largest, with a greater arm asymmetry than the other three, shows a nucleolar constriction subterminally in its shorter arm. Low-temperature treatment causes further secondary constrictions to appear; these constrictions enable most of the mitotic chromosomes to be identified; the constrictions occur at similar sites in the chromosomes of tail-fin epithelial cells, hepatocytes, and brain cells. Homology between the mitotic and oocyte (lampbrush) nucleolar organizers has been established, and thus the several hundred free nucleoli in oocytes are genetically related to the two nucleoli of diploid somatic interphases. During oocyte development the free nucleoli transform from solid structures to rings and back to solid structures again without detectable increase in number. During the contraction and aggregation of the lampbrush chromosomes within the oocyte nucleus as maturity approaches, in most axolotls the free ring-shaped nucleoli become stretched between the nuclear periphery and central chromosome group, and take on a characteristic beaded appearance. These transformations of the free nucleoli are largely paralleled by forms which nucleoli attached subterminally to the shorter arm of lampbrush chromosome III concurrently assume. The question as to whether fully developed nucleoli detach from the organizer loci and add to the population of free nucleoli in oocytes remains undecided. It may well be that virtually all the DNA-generators of free nucleoli detach from the organizer loci before starting to carry out nucleolar functions, and before there is any significant accumulation of protein and RNA around them. If so, the variability in quantity of attached nucleolar material may not reflect different states in a nucleolar synthesis and detachment cycle, but rather variation in the number of nucleolar DNA Anlagen which happen to remain attached to the organizer loci after the synthesis and detachment of the great majority of the Anlagen has ceased. In occasional oocytes the only chromosomal continuity maintained across the organizer locus consists of a nucleolar ‘double bridge’; this indicates that the genetically persistent (i.e. chromosomal) organizer DNA bears the same structural relationship to neighbouring parts of a lampbrush chromosome as any other chromomere with its attendant pair of lateral loops. The lampbrush chromosomes of the axolotl have been provisionally mapped. The centromeres are represented by short portions of chromosome axis without lateral loops, and there are two spheres close to the centromeres of both chromosome VI and chromosome XIII. Other recognition characters are inconspicuous or not very reliable, and features of the lampbrush chromosomes related to the low-temperature induced secondary constrictions of mitotic chromosomes have not been identified.

Banding in mitotic chromosomes of Brassica campestris var. pekinensis with a trypsin–Giemsa method

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 899-901 ◽  
Author(s):  
Soryu Nishibayasahi
Keyword(s):  
Banding Pattern ◽  
Brassica Campestris ◽  
Chromosome Size ◽  
Mitotic Chromosomes ◽  
Metaphase Chromosomes ◽  
Secondary Constrictions

In Brassica campestris var. pekinensis cv. CR-strong, the karyotype comprised 12 median, 6 submedian, and 2 sub-terminal chromosomes. Secondary constrictions were observed in the two subterminal chromosomes. Banding pattern appeared very clearly in metaphase chromosomes with a trypsin–Giemsa method. It was possible to classify the chromosomes into 10 types (C1–C10), based on the chromosome size, shape, and banding pattern.Key words: Brassica campestris var. pekinensis, mitotic chromosomes, G-banding.

Immunolocalization of three oocyte nuclear proteins during oogenesis and embryogenesis in Pleurodeles

Development ◽  
1987 ◽  
Vol 101 (4) ◽  
pp. 715-728
Author(s):  
C. Abbadie ◽  
D. Boucher ◽  
J. Charlemagne ◽  
J.C. Lacroix
Keyword(s):  
Adult Development ◽  
Nuclear Proteins ◽  
Oocyte Nucleus ◽  
Lampbrush Chromosomes ◽  
Mitotic Chromosomes ◽  
Midblastula Transition ◽  
Adult Age ◽  
Young Embryo ◽  
Stock Pile ◽  
Oocyte Nuclear Proteins

The location of three proteins of the oocyte nucleus of Pleurodeles was studied during oogenesis and embryogenesis using monoclonal antibodies A33/22, C3/1 and C36/1. Immunoblotting of two-dimensional gel electrophoregrams of oocyte nuclear proteins showed that these antibodies recognized proteins whose relative molecular masses and isoelectric points were 80×103 and 6á4, 175×103 and 5 and 270×103 and 7, respectively. In the oocyte, all three proteins were nucleoplasmic; those revealed by antibodies A33/22 and C36/1 were detected on lampbrush chromosomes: the first one on the RNP matrix of the loops, and the second one on both the loops and the chromomeres. Protein A33/22 was observed in most nuclei during embryonic, larval and adult development, except for the young embryo, before the midblastula transition. The distribution of this protein in the oocyte and its behaviour during development suggest that it might be involved in the packaging of RNAs during transcription. Antibody C3/1 recognized an oocyte nucleoplasmic protein with biochemical and biophysical properties similar to those of protein N1-N2. After oocyte maturation, the protein moved into the cytoplasm of the animal hemisphere and, from fertilization to the midblastula stage, it shifted from the cytoplasm into the nuclei as cell division proceeded. Starting from the gastrula stage, this protein became specific to the endoderm nuclei. After hatching, it was no longer detectable. This behaviour seems to correspond to that of a nuclear protein issued from the maternal stock pile. Protein C36/1 behaved similarly during early development, but remained in most nuclei after neurulation until the adult age, with a pattern similar to that of protein A33/22. In addition, it was present on the mitotic chromosomes. Its association with mitotic as well as lampbrush chromosomes connects it with the DNP fibre proteins.

scholarly journals Chromosome number and secondary constriction variation in 51 accessions of a citrus germplasm bank

1997 ◽  
Vol 20 (3) ◽  
pp. 489-496 ◽  
Author(s):  
Marcelo Guerra ◽  
Andrea Pedrosa ◽  
Ana Emília Barros e Silva ◽  
Maria Tereza Marquim Cornélio ◽  
Karla Santos ◽  
...  
Keyword(s):  
Secondary Constriction ◽  
Chromatin Condensation ◽  
Proximal Region ◽  
Citrus Species ◽  
Germplasm Bank ◽  
Mitotic Chromosomes ◽  
Citrus Germplasm ◽  
Numerical Variation ◽  
Subterminal Region ◽  
Secondary Constrictions

The mitotic chromosomes of 51 citrus accessions from the Centro Nacional de Pesquisa em Mandioca e Fruticultura Tropical, Cruz das Almas, BA, Brazil, were analyzed. The sample included representatives of 20 Citrus species, one of Poncirus and seven hybrids. All accessions showed 2n = 18 without any evidence of numerical variation. The most clearly variable karyotype feature was the number and position of secondary constrictions (SECs). In 19 accessions the SECs were not identified, mainly due to the degree of chromatin condensation. In the remainder they varied in number from one to three per karyotype. They were found in the proximal region of one of the three largest chromosome pairs, in the terminal/subterminal region of a smaller chromosome or, more seldom, terminally in a larger chromosome. Only in a few cases were such constrictions observed simultaneously in both homologues of the same chromosome pair. The high variability of this karyotype feature may be due to the activation of this region in the previous interphase but may also indicate a high structural variability and heterozygosity of citrus germplasms

MARQUAGE A L'ARGENT AMMONIACAL DESCHROMOSOMES MITOTIQUES ET DES NOYAUX QUIESCENTS DE L'URODELE PLEURODELES WALTLII

1982 ◽  
Vol 24 (5) ◽  
pp. 541-548 ◽  
Author(s):  
Simone Bailly
Keyword(s):  
Cold Treatment ◽  
Silver Deposit ◽  
Mitotic Chromosomes ◽  
Interphase Nuclei ◽  
Pleurodeles Waltlii ◽  
Secondary Constrictions ◽  
Made In

Silver ammoniacal staining (Ag-As), specific for nuclear organizer regions (NORs) of mammals, has been applied to the interphase nuclei and to the mitotic chromosomes of the Triton Pleurodeles waltlii Michahelles. The banding on the chromosomes by the silver preferentially stains the pericentromeric zones where, after cold treatment, secondary constrictions appear. The metaphase karyotype (2n = 24) consists of two pairs of NORs which also stain with silver but to a lesser degree. It is also the same for the centromeres. This banding of zones other than those of the NORs is notable, not only in connection with the observations made in the case of the mammals, but also in connection with results obtained with other amphibians. An interpretation is given. The interphase nuclei also present sites of silver deposit. In the majority of cases, the sites correspond to the nucleoli. Nevertheless, supernumerary sites of deposit were apparent in a number of nuclei. This phenomenon cannot be explained clearly.[Translated by the journal]

scholarly journals Chromosomal characterization and physical mapping of the 5S and the 18S-5.8S-25S ribosomal DNA in Helianthus argophyllus, with new data from Helianthus annuus

Genome ◽  
1999 ◽  
Vol 42 (1) ◽  
pp. 110-115 ◽  
Author(s):  
T Cuéllar ◽  
J Orellana ◽  
E Belhassen ◽  
J L Bella
Keyword(s):  
Ribosomal Dna ◽  
Physical Mapping ◽  
Dna Sequences ◽  
5S Rdna ◽  
The Other ◽  
Mitotic Chromosomes ◽  
Introgression Breeding ◽  
C Banding ◽  
Interspecific Differences ◽  
Secondary Constrictions

The characterization of the mitotic chromosomes of Helianthus argophyllus by means of Feulgen staining, Giemsa C-banding, and the usual DNA sequence-specific fluorochromes allows a chromosomal classification of this species, and shows that two kinds of heterochromatin co-exist equilocally in its chromosomes. One type is confined to the pericentromeric areas of all the chromosomes and the other is associated with the secondary constrictions of the satellite chromosomes. This species is evolutionarily very close to H. annuus with which it is involved in introgression breeding programs. Since these two species show no intra- or interspecific differences with the above treatments, we have used C-banding followed by DAPI, chromomycin A3 or Acridine Orange, and the fluorescent in situ hybridization (FISH) with 5S and 18S-25S ribosomal DNA probes to characterize further the chromosomes of both species in an attempt to find practically applicable chromosomal markers. Our results confirm the heterogeneity of the heterochromatin in these species and show that neither its distribution nor its response to distinct fluorochrome treatments allows better discrimination of the chromosomes within or between the species. On the other hand, the 18S-5.8S-25S rDNA arrays are located in the secondary constrictions of the satellited SM7, SM10, and ST13 pairs and the 5S-rDNA genes are interstitially placed on the short arm of the SM7 and SM11 chromosomes in both species. This permits these chromosomes to be distinguished and provides markers which may be helpful for further physical mapping of DNA sequences in these species.Key words: chromosome banding, sunflower cytogenetics, heterochromatin, ribosomal DNA mapping, FISH.

Some trends in the evolution of very large chromosomes

1978 ◽  
Vol 283 (997) ◽  
pp. 309-318 ◽  
Keyword(s):  
Molecular Mechanisms ◽  
Repetitive Sequences ◽  
Repeated Sequence ◽  
Lampbrush Chromosomes ◽  
Mitotic Chromosomes ◽  
Rapid Divergence ◽  
Cytological Localization ◽  
Chromosome I ◽  
Heavy Labelling

The general features of the arrangement and cytological distribution of repeated sequences in animal chromosomes are reviewed. These features include internal repetitiveness, conservation of clearly functional sequences, rapid divergence of certain classes of repeated sequence with subsequent fixation of families of diverged sequences, and well defined cytological localization of large blocks of sequences in specific parts of the chromosome set. Moderately or ‘middle’ repetitive (m.r.) sequences constitute a large part of the genomes of higher organisms, they seem to accumulate in a balanced manner within chromosome sets, they are mainly responsible for genome growth, and they are interspersed with sequences of other kinds. Little is known about their cytological distribution. Four experiments are described, each of which aimed to locate middle repetitive sequences in the chromosomes of a salamander and a newt. Tritiated m.r. DNA from Plethodon cinereus binds in a non-random fashion to the meiotic diplotene and mitotic chromosomes of the same species, suggesting a non-random distribution of m.r. sequences on these chromosomes. The same DNA, hybridized in situ to the RNA transcripts on the loops of lampbrush chromosomes, produces light and widespread labelling of many loops, but intense labelling of six pairs of loops, each of which lies near to a centromere. Similar experiments in which newt m.r. DNA was hybridized in situ to newt lampbrush chromosomes showed heavy labelling of about 30 loop pairs on each of the long heteromorphic arms of chromosome I, but very little labelling elsewhere. Autoradiographs of newt mitotic chromosomes hybridized with newt m.r. DNA showed rather even labelling of all chromosomes including chromosome I. The significance of the heavy labelling of lampbrush loops near centromeres and on the heteromorphic arms of the newt chromosome I is discussed in relation to possible cytological and molecular mechanisms for generating and preserving families of tandemly linked and cytologically localized m.r. sequences.

scholarly journals Comparison of active transcription regions of lampbrush chromosomes with the mitotic chromosome G pattern in the European domestic goose <i>Anser anser</i>

2011 ◽  
Vol 54 (1) ◽  
pp. 69-82
Author(s):  
K. Andraszek ◽  
E. Smalec
Keyword(s):  
Mitotic Chromosome ◽  
Complete Information ◽  
Lampbrush Chromosomes ◽  
Sources Of Information ◽  
Mitotic Chromosomes ◽  
Anser Anser ◽  
Transcription Activity ◽  
Meiotic Chromosomes ◽  
Dividing Cells ◽  
Active Transcription

Abstract. The most complete information on the karyotype is acquired through the observation of chromosomes obtained from dividing cells. A high number of chromosomes and the presence of microchromosomes in the bird karyotype have made cytogeneticists look for other sources of information on chromosomes. Information sources of great value for the bird karyotype analysis are meiotic chromosomes, specifically represented by lampbrush chromosomes. Lampbrush chromosomes (LBCs) found in developing oocytes of birds are perceived as a new model in cytogenetics which is especially important in the analysis of bird chromosomes. A typical LBC analysis enables one to assess transcription activity on the basis of LBC morphology (inactive chromomeres and side loops). A comparison of lampbrush chromosome transcription activity and the GTG pattern of the corresponding mitotic chromosomes have proven that active transcription regions with side loops correspond to G-positive bands on mitotic chromosomes.

Sulfhydryl bond formation is a prerequisite for proper cycling of centrosomes and chromosomes in mammalian tissue culture cells

1993 ◽  
Vol 51 ◽  
pp. 342-343
Author(s):  
Heide Schatten ◽  
Neidhard Paweletz ◽  
Ron Balczon
Keyword(s):  
Tissue Culture ◽  
Cell Cycle Progression ◽  
Group Formation ◽  
Sulfhydryl Group ◽  
Mammalian Tissue ◽  
Mitotic Chromosomes ◽  
Microtubule Network ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Transmission Electron

To study the role of sulfhydryl group formation during cell cycle progression, mammalian tissue culture cells (PTK2) were exposed to 100¼M 2-mercaptoethanol for 2 to 6 h during their exponential phase of growth. The effects of 2-mercaptoethanol on centrosomes, chromosomes, microtubules, membranes and intermediate filaments were analyzed by transmission electron microscopy (TEM) and by immunofluorescence microscopy (IFM) methods using a human autoimmune antibody directed against centrosomes (SPJ), and a mouse monoclonal antibody directed against tubulin (E7). Chromosomes were affected most by this treatment: premature chromosome condensation was detected in interphase nuclei, and the structure in mitotic chromosomes was altered compared to control cells. This would support previous findings in dividing sea urchin cells in which chromosomes are arrested at metaphase while the centrosome splitting cycle continues. It might also support findings that certairt-sulfhydryl-blocking agents block cyclin destruction. The organization of the microtubule network was scattered probably due to a looser organization of centrosomal material at the interphase centers and at the mitotic poles.

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.

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