Molecular cytogenetics of the ribosomal (18S + 28S and 5S) DNA loci in primitive and advanced urodele amphibians

Genome ◽  
1993 ◽  
Vol 36 (4) ◽  
pp. 762-773 ◽  
Author(s):  
Stefania De Lucchini ◽  
Irma Nardi ◽  
Giuseppina Barsacchi ◽  
Renata Batistoni ◽  
Francesca Andronico
Keyword(s):  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Intraspecific Variability ◽  
Species Group ◽  
28S Rdna ◽  
Evolutionary Trend ◽  
Amphibian Species ◽  
Rdna Sites ◽  
Rdna Loci ◽  
Group A

In the present work we performed a cytogenetic analysis of the ribosomal (18S + 28S and 5S) loci in amphibian species belonging to the advanced family Salamandridae (genera Triturus, Salamandra, and Salamandrina) and in the primitive hynobiid Salamandrella keyserlingii (family Hynobiidae). In each analyzed karyotype the 5S rDNA sites appear to be stable, and definite in number, while an intraspecific variability both in number and chromosomal location of the 18S + 28S rDNA loci has been found in some Triturus species. In particular, an evolutionary trend toward a large intraspecific variability of the 18S + 28S rDNA loci has been found in the T. vulgaris species group. A structural analysis of the ribosomal repetition units demonstrates the occurrence of a length polymorphism within the 18S + 28S rDNA repeats in the examined species of the family Salamandridae; however, this polymorphism is rather limited, even in those Triturus species characterized by high intragenomic variability of the ribosomal sites. We show that in T. vulgaris meridionalis the variant repetition units actually segregate with individual chromosomes. This implies that they are not intermingled in the ribosomal clusters.Key words: molecular cytogenetics, ribosomal genes, Salamandridae, Hynobiidae.

Evolution of Bird Sex Chromosomes Narrated by Repetitive Sequences: Unusual W Chromosome Enlargement in Gallinula melanops (Aves: Gruiformes: Rallidae)

2019 ◽  
Vol 158 (3) ◽  
pp. 152-159 ◽  
Author(s):  
Ricardo J. Gunski ◽  
Rafael Kretschmer ◽  
Marcelo Santos de Souza ◽  
Ivanete de Oliveira Furo ◽  
Suziane A. Barcellos ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
18S Rdna ◽  
Organizer Region ◽  
Repetitive Sequences ◽  
Nucleolar Organizer Region ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Nucleolar Organizer ◽  
W Chromosome ◽  
Rdna Sites

Among birds, species with the ZZ/ZW sex determination system generally show significant differences in morphology and size between the Z and W chromosomes (with the W usually being smaller than the Z). In the present study, we report for the first time the karyotype of the spot-flanked gallinule (Gallinula melanops) by means of classical and molecular cytogenetics. The spot-flanked gallinule has 2n = 80 (11 pairs of macrochromosomes and 29 pairs of microchromosomes) with an unusual W chromosome that is larger than the Z. Besides being totally heterochromatic, it has a secondary constriction in its long arm corresponding to the nucleolar organizer region, as confirmed by both silver staining and mapping of 18S rDNA probes. This is an unprecedented fact among birds. Additionally, 18S rDNA sites were also observed in 6 microchromosomes, while 5S rDNA was found in just 1 microchromosomal pair. Seven out of the 11 used microsatellite sequences were found to be accumulated in microchromosomes, and 6 microsatellite sequences were found in the W chromosome. In addition to the involvement of heterochromatin and repetitive DNAs in the differentiation of the large W chromosome, the results also show an alternative scenario that highlights the plasticity that shapes the evolutionary history of bird sex chromosomes.

scholarly journals Intraspecific polymorphism of ribosomal DNA loci number and morphology in Brachypodium pinnatum and Brachypodium sylvaticum

2012 ◽  
Vol 17 (4) ◽  
Author(s):  
Ewa Breda ◽  
Elzbieta Wolny ◽  
Robert Hasterok
Keyword(s):  
5S Rdna ◽  
Staining Technique ◽  
Rdna Locus ◽  
Chromosomal Distribution ◽  
Metaphase Chromosomes ◽  
Brachypodium Sylvaticum ◽  
Rdna Sites ◽  
Rdna Loci ◽  
35S Rdna ◽  
25S Rdna

AbstractThe genus Brachypodium has become the target of extensive cytomolecular studies since one of its representatives, B. distachyon, has been accepted as a model plant for temperate cereals and forage grasses. Recent preliminary studies suggested that intraspecific rDNA polymorphism can occur in at least two members of the genus, B. sylvaticum and B. pinnatum, so the aim of this study was to further analyse this phenomenon. FISH with 25S rDNA and 5S rDNA probes was performed on somatic metaphase chromosomes, supplemented by the silver staining technique which distinguishes transcriptionally active from inactive 18S-5.8S-25S rDNA loci. The number, size and chromosomal distribution of 5S rDNA loci were very constant: two loci were invariably observed in all studied diploid accessions of both species, while four 5S rDNA loci were present in the tetraploid B. pinnatum. In contrast to 5S rDNA loci, those of the 35S rDNA were more variable. Two or three loci were observed in the diploid B. pinnatum and four in tetraploid accessions. In chromosome complements of B. sylvaticum accessions from two to six 35S rDNA sites were detected. Regardless of total rDNA locus number, only two were transcriptionally active in diploid accessions of both species, while two or four were active in the tetraploid B. pinnatum. Additionally, the fluorescent CMA/DAPI banding method was used to identify the relation between rDNA sites and CMA+ bands. It was revealed that the number and chromosomal distribution of CMA+ bands are in congruence only with 35S rDNA loci which gave strong FISH signals.

scholarly journals The genome structure of Arachis hypogaea (Linnaeus, 1753) and an induced Arachis allotetraploid revealed by molecular cytogenetics

2018 ◽  
Vol 12 (1) ◽  
pp. 111-140 ◽  
Author(s):  
Eliza F. de M. B. do Nascimento ◽  
Bruna V. dos Santos ◽  
Lara O. C. Marques ◽  
Patricia M. Guimarães ◽  
Ana C. M. Brasileiro ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Genome Structure ◽  
Diploid Species ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Rdna Locus ◽  
Genetic Changes ◽  
Rdna Loci ◽  
Cultivated Plant ◽  
Fish Signal

Peanut,Arachishypogaea(Linnaeus, 1753) is an allotetraploid cultivated plant with two subgenomes derived from the hybridization between two diploid wild species,A.duranensis(Krapovickas & W. C. Gregory, 1994) andA.ipaensis(Krapovickas & W. C. Gregory, 1994), followed by spontaneous chromosomal duplication. To understand genome changes following polyploidy, the chromosomes ofA.hypogaea, IpaDur1, an induced allotetraploid (A.ipaensis×A.duranensis)4xand the diploid progenitor species were cytogenetically compared. The karyotypes of the allotetraploids share the number and general morphology of chromosomes; DAPI+bands pattern and number of 5S rDNA loci. However, one 5S rDNA locus presents a heteromorphic FISH signal in both allotetraploids, relative to corresponding progenitor. Whilst forA.hypogaeathe number of 45S rDNA loci was equivalent to the sum of those present in the diploid species, in IpaDur1, two loci have not been detected. Overall distribution of repetitive DNA sequences was similar in both allotetraploids, althoughA.hypogaeahad additional CMA3+bands and few slight differences in the LTR-retrotransposons distribution compared to IpaDur1. GISH showed that the chromosomes of both allotetraploids had preferential hybridization to their corresponding diploid genomes. Nevertheless, at least one pair of IpaDur1 chromosomes had a clear mosaic hybridization pattern indicating recombination between the subgenomes, clear evidence that the genome of IpaDur1 shows some instability comparing to the genome ofA.hypogaeathat shows no mosaic of subgenomes, although both allotetraploids derive from the same progenitor species. For some reasons, the chromosome structure ofA.hypogaeais inherently more stable, or, it has been at least, partially stabilized through genetic changes and selection.

scholarly journals Contributions to the systematic of Pimelodidae (Osteichthyes, Siluriformes): basic and molecular cytogenetics on seven species of Pimelodus from three Brazilian hydrographic systems

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
Simone C. Girardi ◽  
Carla S. Pavanelli ◽  
Vladimir P. Margarido
Keyword(s):  
18S Rdna ◽  
Molecular Cytogenetics ◽  
5S Rdna ◽  
Neotropical Region ◽  
Valid Species ◽  
Rdna Sites ◽  
The Family ◽  
Rdna Fish ◽  
Pimelodus Maculatus ◽  
Cytogenetic Methods

ABSTRACT Pimelodidae harbors several species and is widely distributed throughout the Neotropical region. Pimelodus is the genus with the largest number of species, however it is a polyphyletic group. Cytogenetic analyzes of the valid species still covers less than half of them. Herein, seven Pimelodus species from three Brazilian hydrographic systems were analyzed through basic (Giemsa, AgNORs and C banding) and molecular (5S and 18S rDNA-FISH) cytogenetic methods. All species had 2n=56 chromosomes with different karyotype formulas observed among the species. AgNORs were corresponding to 18S rDNA and localized on long arm of one chromosome pair in all species. Heterochromatin distribution follows the pattern commonly verified in the family and allows to identify each one of the studied species. 5S rDNA marker was interspecifically variable in number and position of cistrons. Pimelodus ortmanni had B chromosomes varying intra and inter-individually. We performed a discussion on our own and available cytogenetic data for Pimelodidae, and the associating of them with available phylogeny enable us identifying features that distinguish subgroups within Pimelodidae, such as NORs location (terminal/long arm for species belonging to “Iheringichthys-Parapimelodus” and “Pimelodus maculatus” subclades) and location of 5S rDNA sites (pericentromeric/interstitial/ long arm for species belonging to Pimelodus group).

scholarly journals Analyses of the Updated “Animal rDNA Loci Database” with an Emphasis on Its New Features

2021 ◽  
Vol 22 (21) ◽  
pp. 11403
Author(s):  
Jana Sochorová ◽  
Francisco Gálvez ◽  
Roman Matyášek ◽  
Sònia Garcia ◽  
Aleš Kovařík
Keyword(s):  
Sex Chromosomes ◽  
5S Rdna ◽  
High Variability ◽  
Rrna Genes ◽  
45S Rdna ◽  
Data Analyses ◽  
Rdna Sites ◽  
Rdna Loci ◽  
Staining Methods ◽  
Active Nors

We report on a major update to the animal rDNA loci database, which now contains cytogenetic information for 45S and 5S rDNA loci in more than 2600 and 1000 species, respectively. The data analyses show the following: (i) A high variability in 5S and 45S loci numbers, with both showing 50-fold or higher variability. However, karyotypes with an extremely high number of loci were rare, and medians generally converged to two 5S sites and two 45S rDNA sites per diploid genome. No relationship was observed between the number of 5S and 45S loci. (ii) The position of 45S rDNA on sex chromosomes was relatively frequent in some groups, particularly in arthropods (14% of karyotypes). Furthermore, 45S rDNA was almost exclusively located in microchromosomes when these were present (in birds and reptiles). (iii) The proportion of active NORs (positively stained with silver staining methods) progressively decreased with an increasing number of 45S rDNA loci, and karyotypes with more than 12 loci showed, on average, less than 40% of active loci. In conclusion, the updated version of the database provides some new insights into the organization of rRNA genes in chromosomes. We expect that its updated content will be useful for taxonomists, comparative cytogeneticists, and evolutionary biologists. 

scholarly journals On the brink of extinction: two new species of Anomaloglossus from French Guiana and amended definitions of Anomaloglossus degranvillei and A. surinamensis (Anura: Aromobatidae)

Zootaxa ◽  
2018 ◽  
Vol 4379 (1) ◽  
pp. 1 ◽  
Author(s):  
FOUQUET ANTOINE ◽  
JEAN-PIERRE VACHER ◽  
ELODIE A. COURTOIS ◽  
BENOIT VILLETTE ◽  
HUGO REIZINE ◽  
...  
Keyword(s):  
New Species ◽  
Body Size ◽  
French Guiana ◽  
Small Body ◽  
Morphological Characters ◽  
Dominant Frequency ◽  
Species Group ◽  
Amphibian Species ◽  
North Eastern ◽  
Group A

A large portion of the amphibian species occurring in Amazonia remains undescribed. A recent study on species delineation in Anomaloglossus, a genus endemic to the Guiana Shield, demonstrated the existence of two undescribed species previously identified as A. degranvillei, which we describe herein. In addition to divergence at the molecular level, these two new taxa are also distinguished by subtle morphological characters and substantial differences in the advertisement calls (note length, dominant frequency, note structure). One species occurs in the hilly lowlands of north-eastern French Guiana and is mainly distinguished from its closest relatives by a small body size (15.9–18.8 mm in males) and by vocalisations characterized by the emission of short notes of 0.09 s on average. The other species is only known from the Itoupé Massif in southern French Guiana and is mainly distinguished from its closest relatives by a moderate body size (19.4–20.4 mm in males) and by vocalisations characterized by the emission of long notes of 0.23 s on average. We also provide amended definitions for two previously described species in the A. degranvillei species group: A. degranvillei, which is endemic to a few massifs in central French Guiana, and A. surinamensis, which is distributed throughout Suriname and French Guiana. The new species described here and A. degranvillei have very narrow ranges within French Guiana and seem to have rapidly declined during the last decade. Therefore, we suggest A. degranvillei and A. dewynteri to be considered as “Critically Endangered” and A. blanci as “Vulnerable” according to the IUCN standards. 

scholarly journals Cytogenetic characterization, rDNA mapping and quantification of the nuclear DNA content in Seriolella violacea Guichenot, 1848 (Perciformes, Centrolophidae)

2020 ◽  
Vol 14 (3) ◽  
pp. 319-328
Author(s):  
Cristian Araya-Jaime ◽  
Claudio Palma-Rojas ◽  
Elisabeth Von Brand ◽  
Alfonso Silva
Keyword(s):  
Dna Content ◽  
Nuclear Dna ◽  
Molecular Cytogenetics ◽  
Fish Fauna ◽  
Nuclear Dna Content ◽  
5S Rdna ◽  
Chromosomal Evolution ◽  
Rdna Sequences ◽  
Rdna Sites ◽  
Karyotype Structure

Seriolella violacea Guichenot, 1848 is an important component of the fish fauna of the Chilean coast and is of great economic interest. Cytogenetic information for the family Centrolophidae is lacking and the genomic size of five of the twenty-eight species described for this family are is barely known. This study aimed to describe for the first time the karyotype structure via classical and molecular cytogenetics analysis with the goal of identifying the constitutive heterochromatin distribution, chromosome organization of rDNA sequences and quantification of nuclear DNA content. The karyotype of S. violacea is composed of 48 chromosomes, with the presence of conspicuous blocks of heterochromatin on chromosomal pairs one and two. FISH assay with a 5S rDNA probe, revealed the presence of fluorescent markings on the heterochromatic block of pair one. The 18S rDNA sites are located exclusively on pair two, characterizing this pair as the carrier of the NOR. Finally, the genomic size of S. violacea was estimated at 0.59 pg of DNA as C-value. This work represents the first effort to document the karyotype structure and physical organization of the rDNA sequences in the Seriolella genome, contributing with new information to improve our understanding of chromosomal evolution and genomic organization in marine perciforms.

FISH-aimed karyotyping and characterization of Renner complexes in permanent heterozygote Rhoeo spathacea

Genome ◽  
2005 ◽  
Vol 48 (1) ◽  
pp. 145-153 ◽  
Author(s):  
Hieronim Golczyk ◽  
Robert Hasterok ◽  
Andrzej J Joachimiak
Keyword(s):  
5S Rdna ◽  
Chromosome Identification ◽  
Rdna Sites ◽  
Rdna Loci ◽  
Target Fish ◽  
Telomere Association ◽  
25S Rdna ◽  
Dapi Fluorescence

Fluorescence in situ hybridization (FISH) using 25S rDNA, 5S rDNA, and telomere sequences as probes was carried out in the complex permanent heterozygote Rhoeo spathacea. Telomere sites were exclusively terminal. All 10 25S rDNA loci were located distally and appeared transcriptionally active after silver staining. Six distal and 2 interstitial 5S rDNA sites were detected; 2 of the distal sites strictly colocalized with 25S rDNA loci. The 2 intercalary 5S rDNA loci occurred in short arms of 2 chromosomes that conjoined at meiosis. Chromosomes differed as to the amount of AT-rich centric heterochromatin, suggesting involvement of pericentromeric regions in translocations. The possibility of Robertsonian-like rearrangements was discussed. Double target FISH with ribosomal probes along with DAPI fluorescence gave the basis for full chromosome identification in mitosis. The 2 Renner complexes are structurally balanced, both having 5 25S and 4 5S rDNA sites. Centromere clustering, telomere association, a high number of NOR sites, and a strong tendency for formation of joint nucleoli contribute to the preservation of highly polarized Rabl arrangement at interphase. These findings were discussed in relation to meiotic catenation in Rhoeo.Key words: chromosomes, complex heterozygotes, FISH, heterochromatin, interphase, meiotic multivalents, nucleolus, NOR, rDNA, Rhoeo, Renner complexes, translocations.

Uniparental loss of ribosomal DNA in the allotetraploid grass Zingeria trichopoda (2n = 8)

Genome ◽  
2003 ◽  
Vol 46 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Violetta Kotseruba ◽  
Dorota Gernand ◽  
Armin Meister ◽  
Andreas Houben
Keyword(s):  
Ribosomal Dna ◽  
5S Rdna ◽  
45S Rdna ◽  
Rdna Sequences ◽  
Genome Wide ◽  
Rdna Sites ◽  
Rdna Loci ◽  
Subsequent Elimination ◽  
Genome Level

Analysis of the grass Zingeria trichopoda (2n = 8, 2C = 5.3 pg) revealed a dynamic evolution with the following characteristics. (i) Genomic in situ hybridization (GISH) demonstrates that Z. trichopoda evolved from an interspecific hybrid involving a species like contemporary Zingeria biebersteiniana (2n = 4) and a second species with a similar low number of chromosomes. The nucleus of Z. trichopoda is spatially organized at the genome level and the two parental genomes occupy distinct and separate domains of lateral arrangements. (ii) The copy number of the Z. biebersteiniana specific pericentromeric tandem repeat family Zbcen1 is drastically reduced in Z. trichopoda. (iii) GISH in combination with labeled rDNA sequences simultaneously discriminated the two parental genomes and the corresponding 5S and 45S rDNA sites. Hence, following allopolyploidization of Z. trichopoda the Z. biebersteiniana like parental chromosomes probably underwent drastic loss of 45S rDNA. This could have arisen either through the loss ofZ. biebersteiniana derived 45S rDNA or through Z. trichopoda genome-wide homogenization of Z. biebersteiniana type 45S rDNA and subsequent elimination of 45S rDNA loci from Z. biebersteiniana derived chromosomes. Finally, 5S rDNA loci are present in both subgenomes of Z. trichopoda and the chromosomal position of these loci is similar for both Z. biebersteiniana and the Z. biebersteiniana like parental genome of Z. trichopoda.Key words: genome evolution, polyploidy, ribosomal DNA, Poaceae.

Out of the blue: A new rain frog species of the genus Pristimantis (Anura: Craugastoridae) from the northern Cordillera Central in Colombia

Zootaxa ◽  
2020 ◽  
Vol 4838 (1) ◽  
pp. 83-101
Author(s):  
MAURICIO RIVERA-CORREA ◽  
JUAN M. DAZA
Keyword(s):  
New Species ◽  
Cloud Forest ◽  
Species Group ◽  
Amphibian Species ◽  
Cordillera Central ◽  
Species Discovery ◽  
Continuous Sampling ◽  
Allopatric Species ◽  
Group A ◽  
Yellow Coloration

Continuous sampling in well studied areas may lead to new amphibian species discoveries, because population dynamics allow rare species to go unnoticed for years. Based on recent sampling of frogs in the northeastern region of Colombia, here we provide genetic, morphological, and bioacoustics evidence to support the description of a new species of the genus Pristimantis. Phylogenetic analysis suggests the new species is a member of the P. lacrimosus species group, a clade of 25 species that is highly diverse in Ecuador and Peru. This new species is more closely related to allopatric species from Peru and Guyana (i.e. P. olivaceus, P. pluvialis, P. pulchridormientes, and an undetermined Pristimantis). The new species has green-yellow coloration and a remarkable brown interocular band, which is unusual in the genus and which inspired the epithet. Pristimantis zorro sp. nov. has only been found at one locality at 1860 m s.a.l., on the eastern flank of the northern Cordillera Central in Department of Antioquia, Colombia. The new species inhabits the ecotone between the humid cloud forest and open areas. Repeated visits to the type locality suggest high variation in population abundance and/or species detection, because we have occasionally observed many individuals in briefs periods of times. In addition, we discuss the biogeographical and systematic implications of our species discovery. 

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