B Chromosome Diversity and Repetitive Sequence Distribution in an Isolated Population of Akodon montensis (Rodentia, Sigmodontinae)

2018 ◽  
Vol 154 (2) ◽  
pp. 79-85
Author(s):  
Amanda A. Soares ◽  
Jonathan P. Castro ◽  
Pedro Balieiro ◽  
Sidnei Dornelles ◽  
Tiago M. Degrandi ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Repetitive Sequences ◽  
5S Rdna ◽  
B Chromosome ◽  
B Chromosomes ◽  
Telomeric Sequences ◽  
Supernumerary Chromosomes ◽  
Dna Libraries ◽  
Eukaryotic Species ◽  
Size And Morphology

B chromosomes are supernumerary chromosomes found in the karyotypes of approximately 15% of all eukaryotic species. They present parasitic behavior and do not follow the standard Mendelian pattern of inheritance, resulting in an imbalance in gametogenesis. The evolutionary dynamics of B chromosomes is still unknown for many species, but studies indicate that the accumulation of repetitive sequences plays an important role in the differentiation of these elements. We analyzed morphology, frequency, and possible homologies amongst different B chromosomes found in an isolated Akodon montensis population in southern Brazil. Repetitive sequences (18S, 5S rDNA and telomeric sequences) were used to test for their accumulation on the supernumerary chromosomes and describe their localization in the species. The results indicate 4 different B chromosome morphotypes, and DNA libraries were generated for 3 of them. 18S rDNA was labelled polymorphically, except in the B chromosomes, whereas the 5S rDNA was located exclusively in an interstitial position on the long arm of chromosome 5. Chromosome painting with the B probes based on FISH revealed a homologous composition for all B chromosome morphotypes and no homology with the chromosomes in the A complement. B chromosomes found in this population may have a common origin and subsequently diversified in size and morphology.

Plantago lagopus B Chromosome Is Enriched in 5S rDNA-Derived Satellite DNA

2016 ◽  
Vol 148 (1) ◽  
pp. 68-73 ◽  
Author(s):  
Katrin Kumke ◽  
Jiří Macas ◽  
Jörg Fuchs ◽  
Lothar Altschmied ◽  
Jasmeet Kour ◽  
...  
Keyword(s):  
Repetitive Sequences ◽  
Nuclear Genome ◽  
5S Rdna ◽  
B Chromosome ◽  
B Chromosomes ◽  
Specific Marker ◽  
Sequencing Technology ◽  
Plantago Lagopus ◽  
Copy Dna ◽  
Chromosome Segments

B chromosomes are supernumerary dispensable parts of the karyotype which appear in some individuals of some populations in some species. Using advanced sequencing technology, we in silico characterized the high-copy DNA composition of Plantago lagopus with and without B chromosomes. The nuclear genome (2.46 pg/2C) was found to be relatively rich in repetitive sequences, with highly and moderately repeated elements making up 68% of the genome. Besides a centromere-specific marker, we identified a B-specific satellite and a repeat enriched in polymorphic A chromosome segments. The B-specific tandem repeat PLsatB originated from sequence amplification including 5S rDNA fragments.

scholarly journals Evolution of Plant B Chromosome Enriched Sequences

2018 ◽  
Author(s):  
André Marques ◽  
Sonja Klemme ◽  
Andreas Houben
Keyword(s):  
Repetitive Sequences ◽  
B Chromosome ◽  
B Chromosomes ◽  
Supernumerary Chromosomes ◽  
Formation And Evolution ◽  
Chromosome Formation ◽  
The Impact ◽  
Normal Standard ◽  
Shed Light

B chromosomes are supernumerary chromosomes which are found in addition to the normal standard chromosomes (A chromosomes). B chromosomes are well known to accumulate several types of repeats. Although the evolution of B chromosomes has been subject of numerous studies, the mechanisms of accumulation and evolution of repetitive sequences is not fully understood. Recently, new genomic approaches have shed light on the origin and accumulation of different classes of repetitive sequences in the process of B chromosome formation and evolution. Here we discuss the impact of repetitive sequences accumulation on the evolution of plant B chromosomes.

scholarly journals Repetitive DNA landscape in essential A and supernumerary B chromosomes of Festuca pratensis Huds

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rahman Ebrahimzadegan ◽  
Andreas Houben ◽  
Ghader Mirzaghaderi
Keyword(s):  
Repetitive Sequences ◽  
Nuclear Genome ◽  
B Chromosome ◽  
B Chromosomes ◽  
Festuca Pratensis ◽  
Ltr Retrotransposons ◽  
Chromosome Identification ◽  
Satellite Repeats ◽  
Low Pass ◽  
Illumina Sequence

AbstractHere, we characterized the basic properties of repetitive sequences in essential A and supernumerary B chromosomes of Festuca pratensis Huds. This was performed by comparative analysis of low-pass Illumina sequence reads of B chromosome lacking (−B) and B chromosome containing (+B) individuals of F. pratensis. 61% of the nuclear genome is composed of repetitive sequences. 43.1% of the genome are transposons of which DNA transposons and retrotransposons made up 2.3% and 40.8%, respectively. LTR retrotransposons are the most abundant mobile elements and contribute to 40.7% of the genome and divided into Ty3-gypsy and Ty1-copia super families with 32.97% and 7.78% of the genome, respectively. Eighteen different satellite repeats were identified making up 3.9% of the genome. Five satellite repeats were used as cytological markers for chromosome identification and genome analysis in the genus Festuca. Four satellite repeats were identified on B chromosomes among which Fp-Sat48 and Fp-Sat253 were specific to the B chromosome of F. pratensis.

scholarly journals Evolution of Plant B Chromosome Enriched Sequences

Genes ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 515 ◽  
Author(s):  
André Marques ◽  
Sonja Klemme ◽  
Andreas Houben
Keyword(s):  
Repetitive Sequences ◽  
B Chromosome ◽  
B Chromosomes ◽  
Dna Elements ◽  
Formation And Evolution ◽  
The Subject ◽  
Chromosome Formation ◽  
The Impact ◽  
Normal Standard ◽  
Shed Light

B chromosomes are supernumerary chromosomes found in addition to the normal standard chromosomes (A chromosomes). B chromosomes are well known to accumulate several distinct types of repeated DNA elements. Although the evolution of B chromosomes has been the subject of numerous studies, the mechanisms of accumulation and evolution of repetitive sequences are not fully understood. Recently, new genomic approaches have shed light on the origin and accumulation of different classes of repetitive sequences in the process of B chromosome formation and evolution. Here we discuss the impact of repetitive sequences accumulation on the evolution of plant B chromosomes.

Molecular Cytogenetics in Digenean Parasites: Linked and Unlinked Major and 5S rDNAs, B Chromosomes and Karyotype Diversification

2015 ◽  
Vol 147 (2-3) ◽  
pp. 195-207 ◽  
Author(s):  
Daniel García-Souto ◽  
Juan J. Pasantes
Keyword(s):  
Molecular Cytogenetics ◽  
5S Rdna ◽  
B Chromosomes ◽  
Ruditapes Decussatus ◽  
Metazoan Parasites ◽  
Single Chromosome ◽  
Telomeric Sequences ◽  
Digenetic Trematodes ◽  
Parorchis Acanthus ◽  
Morphological Differences

Digenetic trematodes are the largest group of internal metazoan parasites, but their chromosomes are poorly studied. Although chromosome numbers and/or karyotypes are known for about 300 of the 18,000 described species, molecular cytogenetic knowledge is mostly limited to the mapping of telomeric sequences and/or of major rDNA clusters in 9 species. In this work we mapped major and 5S rDNA clusters and telomeric sequences in chromosomes of Bucephalus minimus, B. australis, Prosorhynchoides carvajali (Bucephaloidea), Monascus filiformis (Gymnophalloidea), Parorchis acanthus (Echinostomatoidea), Cryptocotyle lingua (Opisthorchioidea), Cercaria longicaudata, Monorchis parvus (Monorchioidea), Diphterostomum brusinae, and Bacciger bacciger (Microphalloidea). Whilst single major and minor rDNA clusters were mapped to different chromosome pairs in B. minimus and P. acanthus, overlapping signals were detected on a single chromosome pair in the remaining taxa. FISH experiments using major rDNA and telomeric probes clearly demonstrated the presence of highly stretched NORs in most of the digenean taxa analyzed. B chromosomes were detected in the B. bacciger samples hosted by Ruditapes decussatus. Although the cercariae specimens obtained from Donax trunculus, Tellina tenuis, and R. decussatus were in agreement with B. bacciger, their karyotypes showed striking morphological differences in agreement with the proposed assignation of these cercariae to different species of the genus Bacciger. Results are discussed in comparison with previous data on digenean chromosomes.

scholarly journals Molecular analysis of Drosophila melanogaster B chromosomes reveals their origin, composition, and structure

2018 ◽  
Author(s):  
Stacey L. Hanlon ◽  
Danny E. Miller ◽  
Salam Eche ◽  
R. Scott Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Analysis ◽  
Model Organism ◽  
B Chromosome ◽  
B Chromosomes ◽  
Individual Species ◽  
Satellite Repeat ◽  
Supernumerary Chromosomes ◽  
Laboratory Stock ◽  
Composition And Structure

ABSTRACTThe number of chromosomes carried by an individual species is one of its defining characteristics. Some species, however, can also carry supernumerary chromosomes referred to as B chromosomes. B chromosomes were recently identified in a laboratory stock of Drosophila melanogaster—an established model organism with a wealth of genetic and genomic resources—enabling us to subject them to extensive molecular analysis. We isolated the B chromosomes by pulsed-field gel electrophoresis and determined their composition through next-generation sequencing. Although these B chromosomes carry no known euchromatic sequence, they are rich in transposable elements and long arrays of short nucleotide repeats, the most abundant being the uncharacterized AAGAT satellite repeat. Fluorescent in-situ hybridization on metaphase chromosome spreads revealed this repeat is located on Chromosome 4, strongly suggesting the origin of the B chromosomes is Chromosome 4. Cytological and quantitative comparisons of signal intensity between Chromosome 4 and the B chromosomes supports the hypothesis that the structure of the B chromosome is an isochromosome. We also report the identification of a new B chromosome variant in a related laboratory stock. This B chromosome has a similar repeat signature as the original but is smaller and much less prevalent. We examined additional stocks with similar genotypes and did not find B chromosomes, but did find these stocks lacked the AAGAT satellite repeat. Our molecular characterization of D. melanogaster B chromosomes is the first step towards understanding how supernumerary chromosomes arise from essential chromosomes and what may be necessary for their stable inheritance.

scholarly journals B Chromosomes in Free-Living Flatworms of the Genus Macrostomum (Platyhelminthes, Macrostomorpha)

2021 ◽  
Vol 22 (24) ◽  
pp. 13617
Author(s):  
Kira S. Zadesenets ◽  
Nikolay B. Rubtsov
Keyword(s):  
Genome Duplication ◽  
Natural Populations ◽  
B Chromosome ◽  
Laboratory Culture ◽  
B Chromosomes ◽  
Free Living ◽  
Transmission Rates ◽  
Supernumerary Chromosomes

B chromosomes (Bs) or supernumerary chromosomes are extra chromosomes in the species karyotype that can vary in its copy number. Bs are widespread in eukaryotes. Usually, the Bs of specimens collected from natural populations are the object of the B chromosome studies. We applied another approach analyzing the Bs in animals maintained under the laboratory conditions as lines and cultures. In this study, three species of the Macrostomum genus that underwent a recent whole-genome duplication (WGD) were involved. In laboratory lines of M. lignano and M. janickei, the frequency of Bs was less than 1%, while in the laboratory culture of M. mirumnovem, it was nearer 30%. Their number in specimens of the culture varied from 1 to 14. Mosaicism on Bs was discovered in parts of these animals. We analyzed the distribution of Bs among the worms of the laboratory cultures during long-term cultivation, the transmission rates of Bs in the progeny obtained from crosses of worms with different numbers of Bs, and from self-fertilized isolated worms. The DNA content of the Bs in M. mirumnovem was analyzed with the chromosomal in situ suppression (CISS) hybridization of microdissected DNA probes derived from A chromosomes (As). Bs mainly consisted of repetitive DNA. The cytogenetic analysis also revealed the divergence and high variation in large metacentric chromosomes (LMs) containing numerous regions enriched for repeats. The possible mechanisms of the appearance and evolution of Bs and LMs in species of the Macrostomum genus were also discussed.

Chromosomal Localization of 18S-28S rDNA and (TTAGGG)n Sequences in Two South African Dormice of the Genus Graphiurus (Rodentia: Gliridae)

2019 ◽  
Vol 158 (3) ◽  
pp. 145-151 ◽  
Author(s):  
Vanessa Milioto ◽  
Sara Vlah ◽  
Sofia Mazzoleni ◽  
Michail Rovatsos ◽  
Francesca Dumas
Keyword(s):  
South African ◽  
Evolutionary Dynamics ◽  
Repetitive Sequences ◽  
Nucleolus Organizer ◽  
28S Rdna ◽  
Telomeric Sequences ◽  
Nucleolus Organizer Regions ◽  
Interstitial Telomeric Sequences ◽  
Almost All

Classical cytogenetics and mapping of 18S-28S rDNA and (TTAGGG)n sequences by fluorescence in situ hybridization (FISH) was performed on Graphiurus platyops (GPL) and Graphiurus ocularis (GOC) metaphases with the aim to characterize the genomes. In both species, inverted DAPI karyotypes showed the same diploid number, 2n = 46, and hybridization of the (TTAGGG)n probe revealed interstitial telomeric sequences (ITSs) at the centromeres of almost all bi-armed chromosomes. FISH with the rDNA probe localized nucleolus organizer regions (NORs), at the terminal ends of the p arms of the subtelocentric pairs 16 and 17 in both species and detected additional signals on GPL8 and GOC18, 19, and 22. The species have similar karyotypes, but their chromosome pairs 18-22 differ in morphology; these are acrocentric in G. platyops, as also confirmed by C-banding, and subtelocentric in G. ocularis. These differences in pairs 18-22 were also highlighted by hybridization of the telomeric probe (TTAGGG)n, which showed the small p arms in G. ocularis enriched with ITSs. FISH of rDNA probes detected multiple NOR loci in G. ocularis, underlining the intense evolutionary dynamics related to these genes. Although the Graphiurus species analyzed have similar karyotypes, the results on the repetitive sequences indicate a complex pattern of genomic reorganization and evolution occurring in these phylogenetically close species.

scholarly journals Karyological study of cicindelidia trifasciata (coleoptera, cicindelidae) from cuba: evidence of B chromosomes

1999 ◽  
Vol 22 (1) ◽  
pp. 45-48 ◽  
Author(s):  
Sónia J.R. Proença ◽  
M.J. Collares-Pereira ◽  
A.R.M. Serrano
Keyword(s):  
Sex Chromosome ◽  
B Chromosome ◽  
B Chromosomes ◽  
Karyological Study ◽  
Supernumerary Chromosomes ◽  
Sex Chromosome System ◽  
Well Differentiated ◽  
Germinal Tissue

Metaphases from germinal tissue of eight males and seven females of Cicindelidia trifasciata from Cuba were analyzed. The species karyotype does not fit the pattern described for Nearctic cicindelids (2n = 18 + XXY): it has 11 autosome pairs and a sex chromosome system of the X1X2X3Y/ X1X1X2X2 X3X3 type, thus a diploid value of 2n = 26 in males and 2n = 28 in females. The first two autosome pairs were almost twice as large as the remaining chromosomes, and the sex elements were morphologically well differentiated. This population was found to be polymorphic for supernumerary chromosomes at both the intraindividual and interindividual levels. An extra small B chromosome was observed in all metaphases of one male (2n = 27), and every female showed metaphases with one to three small Bs, with a clearly higher frequency of cytotype 2n = 29.

A molecular analysis of the origin of the Crepis capillaris B chromosome

1994 ◽  
Vol 107 (3) ◽  
pp. 703-708 ◽  
Author(s):  
M. Jamilena ◽  
C. Ruiz Rejon ◽  
M. Ruiz Rejon
Keyword(s):  
In Situ Hybridization ◽  
Dna Sequences ◽  
Repetitive Sequences ◽  
B Chromosome ◽  
Dna Probes ◽  
Telomeric Repeats ◽  
Crepis Capillaris ◽  
Telomeric Sequences ◽  
Hybridization Data

The origin of the B chromosome of Crepis capillaris has been studied by using in situ hybridization with different DNA probes. Genomic in situ hybridization (GISH) with DNA from plants with and without Bs as probes indicates that the B chromosome has many DNA sequences in common with A chromosomes, showing no region rich in B-specific sequences. Six additional DNA probes were used to test the possible origin of this B from the standard NOR chromosome (chromosome 3). In the short arm of the NOR chromosome, we detected not only 18 S + 25 S rDNA, but also 5 S rDNA and a specific repetitive sequence from the NOR chromosome (pCcH32); in the heterochromatic bands of the long arm, we found two different repetitive sequences (pCcE9 and pCcD29). In the B chromosome, however, only the 18 S + 25 S rDNA and the telomeric sequences from Arabidopsis thaliana were observed. Our in situ hybridization data with telomeric repeats indicate that the two telomeres of the B are larger than those of the A chromosomes, confirming the isochromosomal nature of this B. Hybridizations of 18 S + 25 S rDNA and telomeric repeats to blots of DNA from plants with and without Bs reveal a high homology between A and B 18 S + 25 S rDNA genes, but some sequence dissimilarities between A and B telomeres. Taken as a whole, these data indicate that the entire B of C. capillaris, although possibly having originated from the standard genome, did not derive directly from the NOR chromosome.

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