Heterochromatin composition and nucleolus organizer activity in four canid species

1986 ◽  
Vol 28 (5) ◽  
pp. 744-753 ◽  
Author(s):  
B. Mayr ◽  
G. Geber ◽  
H. Auer ◽  
M. Kalat ◽  
W. Schleger
Keyword(s):  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Nucleolus Organizer ◽  
Domestic Dog ◽  
Banding Technique ◽  
Dapi Staining ◽  
Distamycin A ◽  
Close Relationship ◽  
Heterochromatin Polymorphism ◽  
Canid Species

Sequential staining with a counterstain-contrasted fluorescent banding technique (chromomycin A3 – distamycin A – DAPI) revealed the occurrence of distamycin A – 4,6-diamidino-2-phenylindole (DA–DAPI) staining heterochromatin in the centromeric regions of chromosomes 33, 36, 37, and 38 in the wolf (Canis lupus pallipes) and of chromosomes 13, 16, and 23 in the blue fox (Alopex lagopus). The red fox (Vulpes vulpes) lacked such regions. Staining with DAPI – actinomycin D produced a QFH-type banding pattern with clearcut differences in the staining behaviour of DA–DAPI positive regions between these three canid species. Staining with the fluorochrome D 287/170 did not preferentially highlight any of the DA–DAPI positive regions in any of them. Counterstain-enhanced chromomycin A3 R-banding and studies of nucleolus organizer region location and activity confirmed a close relationship between the karyotype of the wolf and the domestic dog. Few heterochromatic marker bands were encountered in these two species, but heterochromatin polymorphism was evident in the blue fox.Key words: Canidae, heterochromatin, nucleolus organizers.

Cytogenetic studies in North American minnows (Cyprinidae). XII. Patterns of chromosomal nucleolus organizer region variation among 14 species

1986 ◽  
Vol 64 (9) ◽  
pp. 1869-1877 ◽  
Author(s):  
John R. Gold ◽  
Chris T. Amemiya
Keyword(s):  
North American ◽  
Chromosomal Rearrangements ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Nucleolus Organizer ◽  
Interspecific Variations ◽  
Intraspecific Variations ◽  
Close Relationship ◽  
Chromosomal Changes ◽  
Phylogenetic Hypotheses

The chromosomal nucleolus organizer region (NOR) phenotypes of eight species of North American cyprinid fish are documented. This brings the total number of cyprinid species examined for chromosomal NORs to 14. At least 10 different NOR chromosome phenotypes are identifiable among the 14 species. These interspecific variations include differences in the (haploid) number of chromosomal NORs, the chromosomal location(s) of the NORs, and the type(s) of chromosomes upon which the NOR is located. Intraspecific variations or heteromorphisms of NOR chromosomes also occur, but are of a qualitatively different nature than the NOR variants observed between species. Arrangement of the interspecies NOR differences into phylogenetic hypotheses yields results which are not discordant with present concepts of North American cyprinid taxonomy, and in fact support the hypothesis of a close relationship between the cyprinid genera Notropis and Pimephales. These data suggest that NOR chromosome phenotypes will be useful in resolving problems in cyprinid systematics. The data also show that at least one or more chromosomal changes involving the NOR separate most of the species examined, and that at least nine different chromosomal rearrangements have occurred since the 14 species last shared a common ancestor. This suggests that chromosomal changes in cyprinids have been much more frequent than previously thought.

Mapping of the nucleolus organizer region on chromosome 4 inArabidopsis thaliana

1996 ◽  
Vol 250 (1) ◽  
pp. 123-128
Author(s):  
Georg Haberer ◽  
Thilo C. Fischer ◽  
Ramón A. Torres-Ruiz
Keyword(s):  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Nucleolus Organizer ◽  
Chromosome 4

Hybrid ape offspring of a mating of gibbon and siamang

Science ◽  
1979 ◽  
Vol 205 (4403) ◽  
pp. 308-310 ◽  
Author(s):  
RH Myers ◽  
DA Shafer
Keyword(s):  
Parental Species ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Structural Rearrangement ◽  
Female Offspring ◽  
Nucleolus Organizer ◽  
Single Chromosome ◽  
Symphalangus Syndactylus ◽  
Hylobates Moloch ◽  
Lesser Apes

The serendipitous mating of a male gibbon, Hylobates moloch, and a female siamang, Symphalangus syndactylus, has produced two female offspring born 1 year apart. The hybrid karyotype of 47 chromosomes comprises the haploid complements of the parental species, 22 for the gibbon and 25 for the siamang. Chromosomal G and C banding comparisons revealed no clear homologies between the parental karyotypes except for the single chromosome in each species containing the nucleolus organizer region. The lack of homology suggests that the structural rearrangement of chromosomes has played a major role in the process of speciation for these lesser apes.

scholarly journals The relationship between position and expression of genes on the kangaroo X chromosome suggests a tissue-specific spread of inactivation from a single control site

1988 ◽  
Vol 51 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Jennifer A. Marshall Graves ◽  
Garey W. Dawson
Keyword(s):  
Alternative Hypothesis ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Control Site ◽  
Specific Pattern ◽  
Nucleolus Organizer ◽  
Tissue Specific ◽  
Expression Of Genes ◽  
Control Locus ◽  
The Relationship

SummaryIn marsupials, X chromosome inactivation is paternal and incomplete. The tissue-specific pattern of inactivation of X-linked loci (G6PD, PGK, GLA) has been attributed to a piecemeal inactivation of different regions of the X. We here propose an alternative hypothesis, in which inactivation of the marsupial X is a chromosome-wide event, but is differentially regulated in different tissues. This hypothesis was suggested by the relationship between the positions and activity of genes on the kangaroo paternal X. In the absence of an HPRT polymorphism, we have used somatic cell hybridization to assess the activity of the paternal HPRT allele in lymphocytes and fibroblasts. The absence of the paternal X, and of the paternal forms of G6PD or PGK, from 33 cell hybrids made by fusing HPRT-deficient rodent cells with lymphocytes or fibroblasts of heterozygous females, suggests that the HPRT gene on the paternal X is inactive in both tissues and therefore not selectable. Since HPRT is located medially on the Xq near GLA, which shares the same characteristics of activity, we suggest that the locus-specific and tissue-specific patterns of activity result from a differential spread of inactivation from a single control locus, located near HPRT and GLA, outwards in both directions to G6PD and PGK. The nucleolus organizer region on the short arm does not seem to be part of the inactivated unit.

scholarly journals Characterization of AtNUC-L1 Reveals a Central Role of Nucleolin in Nucleolus Organization and Silencing of AtNUC-L2 Gene in Arabidopsis

2007 ◽  
Vol 18 (2) ◽  
pp. 369-379 ◽  
Author(s):  
Frederic Pontvianne ◽  
Isabel Matía ◽  
Julien Douet ◽  
Sylvette Tourmente ◽  
Francisco J. Medina ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Normal Growth ◽  
Growth Conditions ◽  
Nucleolus Organizer ◽  
Multifunctional Protein ◽  
Eukaryotic Organism ◽  
Model Plant Arabidopsis Thaliana ◽  
Fibrillar Component

Nucleolin is one of the most abundant protein in the nucleolus and is a multifunctional protein involved in different steps of ribosome biogenesis. In contrast to animals and yeast, the genome of the model plant Arabidopsis thaliana encodes two nucleolin-like proteins, AtNUC-L1 and AtNUC-L2. However, only the AtNUC-L1 gene is ubiquitously expressed in normal growth conditions. Disruption of this AtNUC-L1 gene leads to severe plant growth and development defects. AtNUC-L1 is localized in the nucleolus, mainly in the dense fibrillar component. Absence of this protein in Atnuc-L1 plants induces nucleolar disorganization, nucleolus organizer region decondensation, and affects the accumulation levels of pre-rRNA precursors. Remarkably, in Atnuc-L1 plants the AtNUC-L2 gene is activated, suggesting that AtNUC-L2 might rescue, at least partially, the loss of AtNUC-L1. This work is the first description of a higher eukaryotic organism with a disrupted nucleolin-like gene and defines a new role for nucleolin in nucleolus structure and rDNA chromatin organization.

Meiotic behaviour of the holocentric chromosomes of Nezara viridula (Insecta, Heteroptera) analysed by C-banding and silver impregnation

1985 ◽  
Vol 27 (5) ◽  
pp. 491-497 ◽  
Author(s):  
J. P. M. Camacho ◽  
J. Belda ◽  
J. Cabrero
Keyword(s):  
Organizer Region ◽  
Nucleolus Organizer Region ◽  
Nucleolus Organizer ◽  
Silver Impregnation ◽  
Nezara Viridula ◽  
Holocentric Chromosomes ◽  
Cytological Analysis ◽  
C Banding ◽  
I Cells ◽  
Do So

While silver impregnation reveals the presence of kinetochores in monocentric chromosomes, it does not do so in the holocentric system of Nezara viridula. Here, C-banding and silver impregnation techniques reveal that C-heterochromatin is present in the greater part of the Y chromosome and at the nucleolus organizer region (NOR) of the largest autosome (A 1) and in the extra NOR located in the X chromosome of a single exceptional male. Furthermore, one telomere of each autosome appeared lightly C-banded. The largest, A1, bivalent shows chiasmata almost always located at the chromosome ends. This bivalent may orient axially or equatorially in metaphase I cells depending on whether it carries a single chiasma or two chiasmata, respectively. From our cytological analysis we deduce that centromeric activity is preferentially located at the two telomeric ends and that the presence of chiasmata at an end excludes such activity.Key words: diffuse centromere, C-banding, holocentric, insect chromosomes.

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