Cytogenetics of Danish species of Barbarea (Brassicaceae): chromocentres, chromosomes and rDNA sites

Stingless bees of the genus Melipona are subdivided into 4 subgenera called Eomelipona, Melikerria, Melipona sensu stricto, and Michmelia according to species morphology. Cytogenetically, the species of the genus Melipona show variation in the amount and distribution of heterochromatin along their chromosomes and can be separated into 2 groups: the first with low content of heterochromatin and the second with high content of heterochromatin. These heterochromatin patterns and the number of chromosomes are characteristics exclusive to Melipona karyotypes that distinguish them from the other genera of the Meliponini. To better understand the karyotype organization in Melipona and the relationship among the subgenera, we mapped repetitive sequences and analyzed previously reported cytogenetic data with the aim to identify cytogenetic markers to be used for investigating the phylogenetic relationships and chromosome evolution in the genus. In general, Melipona species have 2n = 18 chromosomes, and the species of each subgenus share the same characteristics in relation to heterochromatin regions, DAPI/CMA3 fluorophores, and the number and distribution of 18S rDNA sites. Microsatellites were observed only in euchromatin regions, whereas the (TTAGG)6 repeats were found at telomeric sites in both groups. Our data indicate that in addition to the chromosome number, the karyotypes in Melipona could be separated into 2 groups that are characterized by conserved cytogenetic features and patterns that generally are shared by species within each subgenus, which may reflect evolutionary constraints. Our results agree with the morphological separation of the Melipona into 4 subgenera, suggesting that they must be independent evolutionary lineages.

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Effects of the diploidisation process upon the 5S and 35S rDNA sequences in the allopolyploid species of the Dilatata group of Paspalum (Poaceae, Paniceae)

Australian Journal of Botany ◽

10.1071/bt18236 ◽

2019 ◽

Vol 67 (7) ◽

pp. 521

Author(s):

Magdalena Vaio ◽

Cristina Mazzella ◽

Marcelo Guerra ◽

Pablo Speranza

Keyword(s):

Evolutionary Dynamics ◽

In Situ Hybridisation ◽

5S Rdna ◽

Its Region ◽

Variable Number ◽

Rrna Genes ◽

Fluorescence In Situ Hybridisation ◽

Rdna Sites ◽

35S Rdna ◽

Genome Restructuring

The Dilatata group of Paspalum includes species and biotypes native to temperate South America. Among them, five sexual allotetraploids (x = 10) share the same IIJJ genome formula: P. urvillei Steud, P. dasypleurum Kunze ex Desv., P. dilatatum subsp. flavescens Roseng., B.R. Arrill. & Izag., and two biotypes P. dilatatum Vacaria and P. dilatatum Virasoro. Previous studies suggested P. intermedium Munro ex Morong & Britton and P. juergensii Hack. or related species as their putative progenitors and donors of the I and J genome, respectively, and pointed to a narrow genetic base for their maternal origin. It has not yet been established whether the various members of the Dilatata group are the result of a single or of multiple allopolyploid formations. Here, we aimed to study the evolutionary dynamics of rRNA genes after allopolyploidisation in the Dilatata group of Paspalum and shed some light into the genome restructuring of the tetraploid taxa with the same genome formula. We used double target fluorescence in situ hybridisation of 35S and 5S rDNA probes and sequenced the nrDNA internal transcribed spacer (ITS) region. A variable number of loci at the chromosome ends were observed for the 35S rDNA, from 2 to 6, suggesting gain and loss of sites. For the 5S rDNA, only one centromeric pair of signals was observed, indicating a remarkable loss after polyploidisation. All ITS sequences generated were near identical to the one found for P. intermedium. Although sequences showed a directional homogeneisation towards the putative paternal progenitor in all tetraploid species, the observed differences in the number and loss of rDNA sites suggest independent ongoing diploidisation processes in all taxa and genome restructuring following polyploidy.

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Conserved Organisation of 45S rDNA Sites and rDNA Gene Copy Number among Major Clades of Early Land Plants

PLoS ONE ◽

10.1371/journal.pone.0162544 ◽

2016 ◽

Vol 11 (9) ◽

pp. e0162544 ◽

Cited By ~ 16

Author(s):

Marcela Rosato ◽

Aleš Kovařík ◽

Ricardo Garilleti ◽

Josep A. Rosselló

Keyword(s):

Copy Number ◽

Gene Copy Number ◽

Land Plants ◽

Gene Copy ◽

45S Rdna ◽

Rdna Gene ◽

Rdna Sites ◽

Early Land

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Comparative Karyotype Investigations in the European Crayfish Astacus astacus and A. leptodactylus (Decapoda, Astacidae)

Crustaceana ◽

10.1163/156854011x607015 ◽

2011 ◽

Vol 84 (12-13) ◽

pp. 1497-1510 ◽

Cited By ~ 7

Author(s):

M. Pavlica ◽

M. Mcžić ◽

G. Klobučar ◽

M. Šrut ◽

I. Maguire ◽

...

Keyword(s):

Chromosome Number ◽

Chromosome Complement ◽

Size Difference ◽

45S Rdna ◽

Astacus Astacus ◽

Fluorochrome Staining ◽

Rdna Sites ◽

Freshwater Habitats ◽

Acrocentric Chromosomes

AbstractThis study reports on the chromosome number and karyological characteristics of the endangered species of European crayfish, Astacus astacus and A. leptodactylus (Decapoda, Astacidae), both native to Croatian freshwater habitats. The karyotype of A. astacus and A. leptodactylus consists of 2n = 176 and 2n = 180 chromosomes, respectively. The haploid chromosome complement of A. astacus consists of 52 metacentric, 35 metacentric-submetacentric, and 1 acrocentric chromosomes. Fluorochrome staining with 4,6-diamino-2-phenylindole (DAPI) has revealed that the karyotypes of A. astacus and A. leptodactylus are characterized by large heterochromatic blocks located at centromeric and intercalary positions on the chromosomes. Interstitial heterochromatic blocks were more frequent in A. astacus than in A. leptodactylus. In both species pairing of chromosomes in meiosis was regular with the majority of bivalents in a ring- and a dumbbell-form. Fluorescence in situ hybridization (FISH) has revealed that two 45S rDNA loci were present in the investigated species. In A. astacus one of the two 45S rDNA-bearing chromosome pairs was highly heteromorphic, exhibiting a three-fold size difference between 45S rDNA sites on homologous chromosomes. Such a size difference was significantly less pronounced in A. leptodactylus. The karyotype differences between A. astacus and A. leptodactylus suggest changes in chromosome number as well as position of repetitive DNAs have played a role in the karyotype evolution of the species of Astacus.

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Gene mapping of 5S rDNA sites in eight fish species from the Paraíba do Sul river basin, Brazil

Cytogenetic and Genome Research ◽

10.1159/000078567 ◽

2004 ◽

Vol 106 (1) ◽

pp. 107-110 ◽

Cited By ~ 47

Author(s):

K.F. Kavalco ◽

R. Pazza ◽

L.A.C. Bertollo ◽

O. Moreira-Filho

Keyword(s):

Gene Mapping ◽

River Basin ◽

Fish Species ◽

5S Rdna ◽

Rdna Sites ◽

Paraíba Do Sul River

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Comparative molecular cytogenetics in Melipona Illiger species (Hymenoptera, Apidae)

Sociobiology ◽

10.13102/sociobiology.v65i4.3480 ◽

2018 ◽

Vol 65 (4) ◽

pp. 696 ◽

Cited By ~ 2

Author(s):

Vanderly Andrade-Souza ◽

Olivia Maria Pereira Duarte ◽

Cinthia Caroline Cardoso Martins ◽

Igor Silva Santos ◽

Márcio Gilberto Cardoso Costa ◽

...

Keyword(s):

In Situ Hybridization ◽

Chromosome Number ◽

Fluorescent In Situ Hybridization ◽

Molecular Cytogenetics ◽

Fluorochrome Staining ◽

Rdna Sites ◽

Cytogenetic Studies ◽

Melipona Species ◽

Almost All

Cytogenetic studies in Melipona are scarce with only 24 species analyzed cytogenetically. Of these, six species had the rDNA sites physically mapped and characterized by Fluorescent in situ Hybridization (fish). The aim of this study was to perform karyotype analyzes on Melipona species from different regions of Brazil, with a greater sampling representative of the Amazonian fauna and using conventional, fluorochrome staining and FISH with heterologous rDNA probes. The predominant chromosome number was 2n = 18, however, the subspecies M. seminigra abunensis and M. s. pernigra showed 2n = 22 chromosomes. The karyotypes were symmetrical, however M. bicolor, M. quadrifasciata, M. flavolineata, M. fuscopilosa, M. nebulosa presented the first pair heteromorphic in length. CMA3+ blocks also exhibited heteromorphism of size and in almost all cases coincided with rDNA sites, except for M. crinita and M. nebulosa, which presented additional non-coincident CMA3+ blocks. The CMA/ rDNA sites were terminal and interstitial in species with high heterochromatic content, and pericentromeric in those species with low heterochromatic content. In addition to pointing out cytogenetic features of cytotaxonomic importance, the reorganization of the genome in Melipona is discussed.

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Karyotype analysis in Allium roseum L. (Alliaceae) using fluorescent in situhybridization of rDNA sites and conventional stainings

TURKISH JOURNAL OF BOTANY ◽

10.3906/bot-1408-50 ◽

2015 ◽

Vol 39 ◽

pp. 796-807 ◽

Cited By ~ 3

Author(s):

Arbi GUETAT ◽

Marcela ROSATO ◽

Josep A. ROSSELLÓ ◽

Mohamed BOUSSAID

Keyword(s):

Karyotype Analysis ◽

Rdna Sites ◽

In Situhybridization

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Monocentric chromosomes in Juncus (Juncaceae) and implications for the chromosome evolution of the family

Botanical Journal of the Linnean Society ◽

10.1093/botlinnean/boz065 ◽

2019 ◽

Vol 191 (4) ◽

pp. 475-483 ◽

Cited By ~ 6

Author(s):

Marcelo Guerra ◽

Tiago Ribeiro ◽

Leonardo P Felix

Keyword(s):

In Situ Hybridization ◽

Fluorescent In Situ Hybridization ◽

Chromosome Evolution ◽

Holocentric Chromosomes ◽

Mitotic Chromosomes ◽

Restricted Area ◽

Rdna Sites ◽

The Family ◽

Meiotic Analyses

Abstract Holocentric chromosomes are rare among angiosperms, but have been suggested to be shared by all or most of the species of Cyperaceae and Juncaceae. However, no clear demonstration of the centromere type in Juncus, the largest genus of Juncaceae, has so far been published. Thus, we conducted a detailed chromosomal investigation of four Juncus spp. aiming to identify their centromere type. Mitotic chromosomes were analysed using the fluorochromes CMA and DAPI, fluorescent in situ hybridization (FISH) with rDNA probes and immunodetection of histones H3 phosphorylated at serine 10 (H3-S10ph) and H2A phosphorylated at threonine 133 (H2A-T133ph). DAPI-stained chromosomes of all species displayed typical primary constrictions, which were not related to AT-poor CMA+ heterochromatin or rDNA sites (usually negatively stained with DAPI). Immunodetection with H3-S10ph and H2A-T133ph revealed hyperphosphorylation of pericentromeric and centromeric regions, respectively, in a restricted area, as observed in monocentric chromosomes. Meiotic analyses in J. microcephalus showed no indication of inverted meiosis, commonly found in plants with holocentric chromosomes. Since the species investigated here belong to four different sections of Juncus and all of them display typical monocentric chromosomes, it seems that this kind of centromere is common in the genus and may represent the standard centromere organization for Juncus. If Juncus has monocentric chromosomes, there is no reason to hypothesize that other genera of Juncaceae for which centromeres have not been carefully investigated have holocentric chromosomes.

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A populational survey of 45S rDNA polymorphism in the Jefferson salamander Ambystoma jeffersonianum revealed by fluorescence in situ hybridization (FISH)

Current Zoology ◽

10.1093/czoolo/55.2.145 ◽

2009 ◽

Vol 55 (2) ◽

pp. 145-149 ◽

Cited By ~ 4

Author(s):

Ke Bi ◽

James P. Bogart ◽

Jinzhong Fu

Keyword(s):

In Situ Hybridization ◽

Fluorescence In Situ Hybridization ◽

Dispersal Ability ◽

Habitat Isolation ◽

45S Rdna ◽

Isolated Populations ◽

Ambystoma Jeffersonianum ◽

Rdna Sites ◽

Rdna Polymorphism

Abstract The chromosomal localization of 45S ribosomal RNA genes in Ambystoma jeffersonianum was determined by fluorescence in situ hybridization with 18S rDNA fragment as a probe (FISH-rDNA). Our results revealed the presence of rDNA polymorphism among A. jeffersonianum populations in terms of number, location and FISH signal intensity on the chromosomes. Nine rDNA cytotypes were found in ten geographically isolated populations and most of them contained derivative rDNA sites. Our preliminary study provides strong indication of karyotypic diversification of A. Jeffersonianum that is demonstrated by intraspecific variation of 45S rDNA cytotypes. rDNA cytotype polymorphism has been described in many other caudate amphibians. We predict that habitat isolation, low dispersal ability and decline of effective population size could facilitate the fixation and accumulation of variable rDNA cytotypes during their chromosome evolution.

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