The banded chromosomes of the muskox (Ovibos moschatus)

1989 ◽  
Vol 67 (5) ◽  
pp. 1155-1158 ◽  
Author(s):  
Daniel M. Desaulniers ◽  
W. A. King ◽  
Janice E. Rowell ◽  
Peter F. Flood
Keyword(s):  
Silver Nitrate ◽  
X Chromosome ◽  
Water Buffalo ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Ovibos Moschatus ◽  
Nucleolus Organizer Regions ◽  
The Family ◽  
Silver Nitrate Staining ◽  
Acrocentric Chromosomes

The muskox (Ovibos moschatus), a member of the family Bovidae, has 48 chromosomes consisting of 12 biarmed and 34 acrocentric autosomes, an acrocentric X chromosome, and a small metacentric Y chromosome. To obtain more information about this species, chromosome preparations from cultured lymphocytes were R-banded, C-banded, or stained with silver nitrate. R-banding was sufficient to identify individual chromosomes. C-banding revealed prominent centromeric bands on all acrocentric chromosomes and very faint staining of the centromeric regions of the biarmed chromosomes. This pattern has been observed in other bovids, such as sheep and water buffalo, which also have biarmed and acrocentric chromosomes. Silver nitrate staining revealed a per metaphase average of 5.23 nucleolus organizer regions, the chromosomal sites of rRNA genes. The nucleolus organizer regions were located on the ends of the long arm of three pairs of submetacentric and two pairs of acrocentric autosomes. Similar numbers of terminally located nucleolus organizer regions have been observed in other bovids such as cattle, sheep, and goats. These results parallel those obtained in other members of the family and emphasize the general cytogenetic similarity within the Bovidae.

scholarly journals Cytogenetic Studies on Three Species of Genus Burmagomphus of Family Gomphidae (Odonata: Anisoptera) from India

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Walia Gurinder Kaur ◽  
Chahal Sarabjit Singh ◽  
Singh Navdeep
Keyword(s):  
Chromosome Number ◽  
Germ Cell ◽  
Silver Nitrate ◽  
X Chromosome ◽  
Type Number ◽  
Autosomal Bivalents ◽  
Specific Staining ◽  
The Family ◽  
Cytogenetic Studies ◽  
Silver Nitrate Staining

Male germ cell chromosomes of Burmagomphus divaricatus, Burmagomphus pyramidalis and Burmagomphus sivalikensis of family Gomphidae have been investigated by using conventional staining, C-banding, silver nitrate staining and sequence specific staining. The species were collected from Punjab and Himachal Pradesh, India. All the species possess the chromosome number 2n = 23 which is the type number of the family. Terminal C bands and NOR’s are present at the autosomal bivalents and X chromosome is C positive and NOR rich in all the three species, while m bivalents show variation in distribution of C- heterochromatin and NOR’s. In the sequence specific staining, whole complement shows bright DAPI signals in B. divaricatus, bright CMA3 signals in B. pyramidalis and both DAPI and CMA3 signals in B. sivalikensis.

scholarly journals Chromosome Dynamics Regulating Genomic Dispersion and Alteration of Nucleolus Organizer Regions (NORs)

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 971
Author(s):  
Hirohisa Hirai
Keyword(s):  
Transcriptional Activity ◽  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Dispersion Systems ◽  
Rdna Loci ◽  
Silver Nitrate Staining ◽  
Staining Methods ◽  
Acrocentric Chromosomes ◽  
Reciprocal Associations

The nucleolus organizer regions (NORs) demonstrate differences in genomic dispersion and transcriptional activity among all organisms. I postulate that such differences stem from distinct genomic structures and their interactions from chromosome observations using fluorescence in situ hybridization and silver nitrate staining methods. Examples in primates and Australian bulldog ants indicate that chromosomal features indeed play a significant role in determining the properties of NORs. In primates, rDNA arrays that are located on the short arm of acrocentrics frequently form reciprocal associations (“affinity”), but they lack such associations (“non-affinity”) with other repeat arrays—a binary molecular effect. These “rules” of affinity vs. non-affinity are extrapolated from the chromosomal configurations of meiotic prophase. In bulldog ants, genomic dispersions of rDNA loci expand much more widely following an increase in the number of acrocentric chromosomes formed by centric fission. Affinity appears to be a significantly greater force: associations likely form among rDNA and heterochromatin arrays of acrocentrics—thus, more acrocentrics bring about more rDNA loci. The specific interactions among NOR-related genome structures remain unclear and require further investigation. Here, I propose that there are limited and non-limited genomic dispersion systems that result from genomic affinity rules, inducing specific chromosomal configurations that are related to NORs.

scholarly journals Chromosomal stasis in distinct families of marine Percomorpharia from South Atlantic

2017 ◽  
Vol 11 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Fabilene Gomes Paim ◽  
Leandro Aragão da Hora Almeida ◽  
Paulo Roberto Antunes de Mello Affonso ◽  
Patrícia Elda Sobrinho-Scudeler ◽  
Claudio Oliveira ◽  
...  
Keyword(s):  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Centromeric Heterochromatin ◽  
Single Pair ◽  
Nucleolus Organizer Regions ◽  
Chromosomal Data ◽  
Physical Barriers ◽  
5S Rrna Genes ◽  
Fish Group ◽  
Acrocentric Chromosomes

The weakness of physical barriers in the marine environment and the dispersal potential of fish populations have been invoked as explanations of the apparent karyotype stasis of marine Percomorpha, but several taxa remain poorly studied cytogenetically. To increase the chromosomal data in this fish group, we analyzed cytogenetically three widespread Atlantic species from distinct families: Chaetodipterusfaber Broussonet, 1782 (Ephippidae), Lutjanussynagris Linnaeus, 1758 (Lutjanidae) and Rypticusrandalli Courtenay, 1967 (Serranidae). The three species shared a karyotype composed of 2n=48 acrocentric chromosomes, single nucleolus organizer regions (NORs) and reduced amounts of centromeric heterochromatin. A single NOR-bearing pair was identified in all species by physical mapping of 18S rDNA while non-syntenic 5S rRNA genes were located at centromeric region of a single pair. The similar karyotypic macrostructure observed in unrelated groups of Percomorpharia reinforces the conservative karyoevolution of marine teleosteans. Nonetheless, the species could be differentiated based on the pair bearing ribosomal cistrons, revealing the importance of microstructural analyses in species with symmetric and stable karyotypes.

scholarly journals Cytogenetic studies in three species of Lutjanus (Perciformes: Lutjanidae: Lutjaninae) from the Isla Margarita, Venezuela

2008 ◽  
Vol 6 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Mauro Nirchio ◽  
Rodolfo Rondón ◽  
Claudio Oliveira ◽  
Irani A. Ferreira ◽  
Cesar Martins ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
Chromosome Complement ◽  
Gene Clusters ◽  
Ribosomal Gene ◽  
Nucleolus Organizer ◽  
Rrna Genes ◽  
Single Chromosome ◽  
Nucleolus Organizer Regions ◽  
Robertsonian Rearrangements ◽  
Acrocentric Chromosomes

In the present study, three species of Lutjaninae, Lutjanus analis, L. griseus and L. synagris, were analyzed by conventional Giemsa staining, C-banding and silver staining, to reveal active Nucleolus Organizer Regions (NORs). Fluorescent in situ hybridization (FISH) was also applied to establish the number and location of the ribosomal gene clusters (18S and 5S rRNA genes). Counts of diploid metaphasic cells revealed a diploid modal chromosome complement composed of 48 acrocentric chromosomes in both L. analis and L. griseus. Two cytotypes were observed in L. synagris: cytotype I, with 2n=48 acrocentric chromosomes, found in 19 specimens, and cytotype II, with 46 acrocentric chromosomes and one large metacentric, found in two specimens. The large metacentric, which possibly originated from a Robertsonian rearrangement, was not found to be sex-related. In the three species, constitutive heterochromatin is located in the centromeres of all chromosomes. NORs were detected on the short arms of a single chromosome pair, number 24 in L. analis and number 6 in both cytotypes of L. synagris. In L. griseus, a polymorphism of the NORs number was detected, by both Ag-staining and FISH, as females show a maximum of three NORs, and males a maximum of six NORs. In all species, minor ribosomal genes were found located on a single chromosome pair. The obtained data, along with those previously reported for other five Lutjanidae species, show that a general chromosome homogeneity occurs within the family, but that derived karyotypes based on Robertsonian rearrangements as well as multiple and variable NORs sites can also be found.

CONSERVATIVE CHROMOSOMAL CHANGE IN THE BAT FAMILY MORMOOPIDAE

1981 ◽  
Vol 23 (3) ◽  
pp. 459-467 ◽  
Author(s):  
Jack W. Sites Jr. ◽  
John W. Bickham ◽  
Mike W. Haiduk
Keyword(s):  
Silver Nitrate ◽  
Nucleolar Organizer ◽  
Nucleolar Organizer Regions ◽  
Positive Band ◽  
Chromosomal Change ◽  
Positive Region ◽  
The Family ◽  
Silver Nitrate Staining ◽  
Acrocentric Chromosomes

G-band patterns are described for the karyotypes of both genera and all subgenera of mormoopid bats. A nomenclatural system is proposed for the mormoopid genome in which each autosomal arm is numbered and all bands on each arm are numbered from the centromere to the telomere. G-band patterns indicate that the karyotypes have remained stable throughout the evolution of the family; both species of Mormoops appear to differ from Pteronotus only by the presence in the former of a prominent G-positive region proximal to the centromere of arm 2. Mormoops blainvilli also possessed a prominent G-positive band in the distal end of arm 9 that stained lightly in all other species. C-band patterns of Mormoops megalophylla showed that most heterochromatic regions were centromeric, and silver-nitrate staining in this species and two species of Pteronotus showed that all possessed three pairs of nucleolar organizer regions on the centromeric ends of acrocentric chromosomes. G-band patterns suggest that the karyotype of all Pteronotus is primitive for the family.

scholarly journals A new karyotype for the genus Cavia from a southern island of Brazil (Rodentia - Caviidae)

1998 ◽  
Vol 21 (1) ◽  
pp. 77-80 ◽  
Author(s):  
A. Gava ◽  
T.R.O. Freitas ◽  
J. Olimpio
Keyword(s):  
X Chromosome ◽  
Nucleolus Organizer ◽  
Southern Coast ◽  
Mammal Species ◽  
Banding Patterns ◽  
Nucleolus Organizer Regions ◽  
Acrocentric Chromosomes ◽  
Southern Island ◽  
Almost All

Intraspecific karyotype variation in mammal species is very common and often caused by centromeric fusion of acrocentric chromosomes. We describe here a new karyotype 2n = 62 (FN = 112) for the genus Cavia from the Moleques do Sul Islands, of the southern coast of Brazil. We analyzed two male and four female karyotypes that had twenty-four biarmed pairs and six pairs of acrocentric chromosomes. The sexual pair consisted of a metacentric X-chromosome and a large acrocentric Y. C-bands were found in the centromeric and pericentromeric regions of almost all chromosomes, except for some small biarmed and acrocentric ones. Nucleolus organizer regions appeared in two biarmed chromosomes, and G-banding patterns were also seen.

Frequency of Ag-stained nucleolus organizer regions in the acrocentric chromosomes of man

1977 ◽  
Vol 37 (1) ◽  
pp. 73-77 ◽  
Author(s):  
A. V. Mikelsaar ◽  
M. Schmid ◽  
W. Krone ◽  
H. G. Schwarzacher ◽  
W. Schnedl
Keyword(s):  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Acrocentric Chromosomes

scholarly journals Comparative analysis based on replication banding reveals the mechanism responsible for the difference in the karyotype constitution of treefrogs Ololygon and Scinax (Arboranae, Hylidae, Scinaxinae)

2017 ◽  
Vol 11 (2) ◽  
pp. 267-283 ◽  
Author(s):  
Simone Lilian Gruber ◽  
Gabriela Isabela Gomes de Oliveira ◽  
Ana Paula Zampieri Silva ◽  
Hideki Narimatsu ◽  
Célio Fernando Baptista Haddad ◽  
...  
Keyword(s):  
Chromosome Banding ◽  
Diploid Number ◽  
Nucleolus Organizer ◽  
Replication Banding ◽  
Nucleolus Organizer Regions ◽  
The Family ◽  
The Difference ◽  
Size And Morphology ◽  
Phylogenetic Revision ◽  
Dna Incorporation

According to the recent taxonomic and phylogenetic revision of the family Hylidae, species of the former Scinaxcatharinae (Boulenger, 1888) clade were included in the resurrected genus Ololygon Fitzinger, 1843, while species of the Scinaxruber (Laurenti, 1768) clade were mostly included in the genus Scinax Wagler, 1830, and two were allocated to the newly created genus JulianusDuellman et al., 2016. Although all the species of the former Scinax genus shared a diploid number of 2n = 24 and the same fundamental number of chromosome arms of FN = 48, two karyotypic constitutions were unequivocally recognized, related mainly to the distinct size and morphology of the first two chromosome pairs. Some possible mechanisms for these differences had been suggested, but without any experimental evidence. In this paper, a comparison was carried out based on replication chromosome banding, obtained after DNA incorporation of 5-bromodeoxiuridine in chromosomes of Ololygon and Scinax. The obtained results revealed that the loss of repetitive segments in chromosome pairs 1 and 2 was the mechanism responsible for karyotype difference. The distinct localization of the nucleolus organizer regions in the species of both genera also differentiates the two karyotypic constitutions.

The nucleolus

2019 ◽  
pp. 147-152
Author(s):  
John C. Lucchesi
Keyword(s):  
Gene Silencing ◽  
Histone H1 ◽  
Nucleolus Organizer ◽  
Linker Histone ◽  
The Other ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Dna Repeats ◽  
Gene Arrays ◽  
Nucleolus Organizer Regions

The nucleolus forms at nucleolus organizer regions (NORs) that consist of clusters of repeated rRNA genes. Transcription of the rRNA genes and processing of the transcripts yields the three types of RNAs necessary for the biogenesis of ribosomes. Only subsets of the rRNA genes present in cells are transcribed. The linker histone H1 plays a specific role in the repression of inactive rRNA genes and in many of the other functions of the nucleolus. One of these functions is gene silencing—the nucleolus is surrounded by a zone of heterochromatin consisting of silenced rRNA gene arrays, DNA repeats that flank the centromeres and chromatin domains that include gene-poor, as well as silent, regions of the genome; any gene associating with this zone is subjected to repression. Other functions include the assembly of telomerase, the regulation of p53 stability and the synthesis of 5S and tRNAs whose genes form clusters in the nucleolus.

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