Population heteromorphisms of Ag-stained nucleolus organizer regions (NORs) in the acrocentric chromosomes of East Indians

1981 ◽  
Vol 59 (4) ◽  
pp. 412-415 ◽  
Author(s):  
Ram S. Verma ◽  
Carole Benjamin ◽  
Jorge Rodriguez ◽  
Harvey Dosik
Keyword(s):  
Nucleolus Organizer ◽  
Nucleolus Organizer Regions ◽  
Acrocentric Chromosomes ◽  
East Indians

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 cytogenetic of six species of Amazonian Peacock bass (Cichla, Cichlinae): intrachromosomal variations and genetic introgression among sympatric species

2020 ◽  
Vol 14 (3) ◽  
pp. 437-451
Author(s):  
Janice Quadros ◽  
Alex M. V. Ferreira ◽  
Patrik F. Viana ◽  
Leandro Marajó ◽  
Ezequiel Oliveira ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
5S Rdna ◽  
Heterochromatic Region ◽  
Sympatric Species ◽  
Nucleolus Organizer ◽  
Genetic Introgression ◽  
Nucleolus Organizer Regions ◽  
River Region ◽  
Cytogenetic Analyses ◽  
Acrocentric Chromosomes

Cytogenetic data for the genus Cichla Bloch et Schneider, 1801 are still very limited, with only four karyotype descriptions to date. The sum of the available cytogenetic information for Cichla species, points to a maintenance of the diploid number of 48 acrocentric chromosomes, considered a typical ancestral feature in cichlids. In the current study, we performed molecular and classical cytogenetic analyses of the karyotype organization of six species of Cichla, the earliest-diverging genus of Neotropical cichlids. We cytogenetically analysed Cichla kelberi Kullander et Ferreira, 2006, Cichla monoculus Agassiz, 1831, Cichla piquiti Kullander et Ferreira, 2006, Cichla temensis Humboldt, 1821, Cichla vazzoleri Kullander et Ferreira, 2006 and Cichla pinima Kullander et Ferreira, 2006, including three individuals that showed mixed morphological characteristics, likely from different species, suggesting they were hybrid individuals. All individuals analysed showed 2n = 48 acrocentric chromosomes, with centromeric heterochromatic blocks on all chromosomes and a terminal heterochromatic region on the q arm of the 2nd pair. Mapping 18S rDNA gave hybridization signals, correlated with the nucleolus organizer regions, on the 2nd pair for all analyzed individuals. However, we found distinct patterns for 5S rDNA: interstitially at the proximal position on 6th pair of four species (C. kelberi, C. pinima, C. piquiti and C. vazzoleri), and on the distal of the 4th pair in two (C. monoculus and C. temensis). Accordingly, we present here new data for the genus and discuss the evolutionary trends in the karyotype of this group of fish. In addition, we provide data that supports the occurrence of hybrid individuals in the Uatumã River region, mainly based on 5S rDNA mapping.

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 Karyotype, C-band and NOR phenotype of Anatolian endemic fish Squalius anatolicus (Bogutskaya, 1997) (Teleostei, Leuciscidae)

2021 ◽  
Vol 38 (3) ◽  
pp. 311-315
Author(s):  
Sevgi Ünal Karakuş ◽  
Muhammet Gaffaroğlu
Keyword(s):  
Chromosome Pair ◽  
Constitutive Heterochromatin ◽  
Nucleolus Organizer ◽  
Submetacentric Chromosome ◽  
Nucleolus Organizer Regions ◽  
C Banding ◽  
Nor Phenotype ◽  
Acrocentric Chromosomes ◽  
Endemic Fish ◽  
Lake Beysehir

The karyotype and distribution of constitutive heterochromatin and nucleolus organizer regions (NORs) of Anatolian leuciscine endemic to Lake Beysehir, Squalius anatolicus (Bogutskaya, 1997) were analyzed respectively using conventional Giemsa-staining, C-banding and Ag-impregnation. Diploid chromosome number was 2n = 50 and karyotype consisted of 7 pairs of metacentric, 13 pairs of submetacentric, 5 pairs of subtelo- to acrocentric chromosomes, NF value equaled 90. Heteromorphic elements indicating sex chromosomes were not detected. C-banding revealed clear pericentromeric constitutive heterochromatin blocks in several chromosomes. Ag-impregnation revealed the size heteromorphism of NORs that covered almost the entire short arms of the middle-sized submetacentric chromosome pair. The karyotype pattern and simple NOR phenotype of S. anatolicus are nearly identical with that found not only in Squalius species analyzed to date but also in many other representatives of the Eurasian leuciscine cyprinids, which indicates remarkable chromosome stasis in this leuciscid lineage.

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 First cytogenetic analysis of lesser gymnures (Mammalia, Galericidae, Hylomys) from Vietnam

2018 ◽  
Vol 12 (3) ◽  
pp. 361-372 ◽  
Author(s):  
Svetlana V. Pavlova ◽  
Larisa S. Biltueva ◽  
Svetlana A. Romanenko ◽  
Natalya A. Lemskaya ◽  
Anton V. Shchinov ◽  
...  
Keyword(s):  
Taxonomic Status ◽  
Genetic Distances ◽  
Nucleolus Organizer ◽  
Telomeric Dna ◽  
Dapi Staining ◽  
Nucleolus Organizer Regions ◽  
Southern Vietnam ◽  
Acrocentric Chromosomes ◽  
First Time

Gymnures are an ancient group of small insectivorous mammals and are characterized by a controversial taxonomic status and the lack of a description of karyotypes for certain species. In this study, conventional cytogenetic techniques (Giemsa, CBG- and GTG-banding, Ag-NOR), CMA3-DAPI staining, and fluorescent in situ hybridization (FISH) with telomeric DNA probes were used to examine for the first time the karyotypes of lesser gymnures of group Hylomyssuillus Müller, 1840 from northern and southern Vietnam. All studied specimens had karyotypes with 2n=48, NFa=64. C-positive heterochromatic blocks existed in centromeric regions of 7 bi-armed autosomes and the submetacentric X chromosome. The Y chromosome is a C-positive and dot-like. The nucleolus organizer regions resided terminally on the short arms of 2 small bi-armed pairs. Positive signals at the telomeres of all chromosomes were revealed by FISH. CMA3-positive blocks were localized on the telomeric and pericentric regions of most bi-armed and acrocentric chromosomes. Despite the large genetic distances between Hylomys Müller, 1840, lesser gymnures from H.suillus-group from northern and southern Vietnam have similar karyotypic characteristics.

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.

scholarly journals Karyotype and chromosomal characteristics of rDNA of Cobitis strumicae Karaman, 1955 (Teleostei, Cobitidae) from Lake Volvi, Greece

2018 ◽  
Vol 12 (4) ◽  
pp. 483-491 ◽  
Author(s):  
Eva Hnátková ◽  
Costas Triantaphyllidis ◽  
Catherine Ozouf-Costaz ◽  
Lukáš Choleva ◽  
Zuzana Majtánová ◽  
...  
Keyword(s):  
Chromosome Pair ◽  
Nucleolus Organizer ◽  
Telomeric Region ◽  
Submetacentric Chromosome ◽  
Rdna Probe ◽  
Nucleolus Organizer Regions ◽  
Heteromorphic Sex Chromosomes ◽  
Acrocentric Chromosomes ◽  
Phylogenetic Lineages

The karyotype of Greek cobitid fish Cobitisstrumicae Karaman, 1955, from Lake Volvi, Greece, a representative of one of its two major intraspecific phylogenetic lineages, was analysed by means of sequential Giemsa-staining, C-banding, silver-staining, CMA3 fluorescence banding and also by in situ hybridization (FISH) with rDNA probe. The diploid chromosome number was 2n = 50, karyotype composed of 10 pairs of metacentric to submetacentric and 15 pairs of subtelocentric to acrocentric chromosomes. The nucleolus organizer regions (NORs) as revealed by Ag- and CMA3 staining and FISH were situated in the telomeric region of the fourth submetacentric chromosome pair. The chromosomes contained very low content of C-positive heterochromatin. No heteromorphic sex chromosomes were detected. This first karyotype report for any species of lineage Bicanestrinia Băcescu, 1962 shows a simple karyotype dominated by acrocentric chromosomes and possessing single NOR-bearing chromosome pair. Cytotaxonomic implications of this finding for the taxonomy of the genus Cobitis Linnaeus, 1758 are further discussed.

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