Pseudodicentric Chromosome Originating from Autosomes 9 and 21 in a Male Patient with Oligozoospermia

Genetic factors are responsible for 15% of male infertility conditions. Numerical and structural chromosomal anomalies (related to the Y chromosome or to the autosomes) are validated genetic factors leading to spermatogenic quantitative defects with a frequency depending on the severity of the phenotype. The most frequent structural chromosomal rearrangements of autosomes are translocations and inversions, whereas dicentric chromosomes involving autosomes are rare. We report a man bearing a pseudodicentric chromosome (9;21) and presenting with oligozoospermia. Extensive cytogenetic analyses were necessary to determine the precise nature of the derivative chromosome and to discount the presence of interstitial telomeric sequences. Defects in spermatogenesis and abnormal segregation at meiosis for existing spermatozoa are proposed and are the likely cause of the reproductive phenotype of the patient.

Download Full-text

Distribution of Interstitial Telomeric Sequences in Primates and the Pygmy Tree Shrew (Scandentia)

Cytogenetic and Genome Research ◽

10.1159/000467634 ◽

2017 ◽

Vol 151 (3) ◽

pp. 141-150 ◽

Cited By ~ 10

Author(s):

Sofia Mazzoleni ◽

Odessa Schillaci ◽

Luca Sineo ◽

Francesca Dumas

Keyword(s):

Dna Sequences ◽

Tree Shrew ◽

Chromosomal Rearrangements ◽

Primate Species ◽

Telomeric Dna ◽

Erythrocebus Patas ◽

Telomeric Sequences ◽

Interstitial Telomeric Sequences ◽

Cercopithecus Petaurista ◽

Almost All

It has been hypothesized that interstitial telomeric sequences (ITSs), i.e., repeated telomeric DNA sequences found at intrachromosomal sites in many vertebrates, could be correlated to chromosomal rearrangements and plasticity. To test this hypothesis, we hybridized a telomeric PNA probe through FISH on representative species of 2 primate infraorders, Strepsirrhini (Lemur catta, Otolemur garnettii, Nycticebus coucang) and Catarrhini (Erythrocebus patas, Cercopithecus petaurista, Chlorocebus aethiops, Colobus guereza), as well as on 1 species of the order Scandentia, Tupaia minor, used as an outgroup for primates in phylogenetic reconstructions. In almost all primate species analyzed, we found a telomeric pattern only. In Tupaia, the hybridization revealed many bright ITSs on at least 11 chromosome pairs, both biarmed and acrocentric. These ITS signals in Tupaia correspond to fusion points of ancestral human syntenic associations, but are also present in other chromosomes showing synteny to only a single human chromosome. This distribution pattern was compared to that of the heterochromatin regions detected through sequential C-banding performed after FISH. Our results in the analyzed species, compared with literature data on ITSs in primates, allowed us to discuss different mechanisms responsible for the origin and distribution of ITSs, supporting the correlation between rearrangements and ITSs.

Download Full-text

Molecular Cytogenetic Characterization of the Sicilian Endemic Pond Turtle Emys trinacris and the Yellow-Bellied Slider Trachemys scripta scripta (Testudines, Emydidae)

Genes ◽

10.3390/genes11060702 ◽

2020 ◽

Vol 11 (6) ◽

pp. 702 ◽

Cited By ~ 1

Author(s):

Rita Scardino ◽

Sofia Mazzoleni ◽

Michail Rovatsos ◽

Luca Vecchioni ◽

Francesca Dumas

Keyword(s):

Karyotype Evolution ◽

Chromosomal Rearrangements ◽

Trachemys Scripta ◽

Turtle Species ◽

Telomeric Sequences ◽

Pond Turtle ◽

Rdna Loci ◽

Cytogenetic Analyses ◽

Staining Methods ◽

Emys Trinacris

Turtles, a speciose group consisting of more than 300 species, demonstrate karyotypes with diploid chromosome numbers ranging from 2n = 26 to 2n = 68. However, cytogenetic analyses have been conducted only to 1/3rd of the turtle species, often limited to conventional staining methods. In order to expand our knowledge of the karyotype evolution in turtles, we examined the topology of the (TTAGGG)n telomeric repeats and the rDNA loci by fluorescence in situ hybridization (FISH) on the karyotypes of two emydids: the Sicilian pond turtle, Emys trinacris, and the yellow-bellied slider, Trachemys scripta scripta (family Emydidae). Furthermore, AT-rich and GC-rich chromosome regions were detected by DAPI and CMA3 stains, respectively. The cytogenetic analysis revealed that telomeric sequences are restricted to the terminal ends of all chromosomes and the rDNA loci are localized in one pair of microchromosomes in both species. The karyotype of the Sicilian endemic E. trinacris with diploid number 2n = 50, consisting of 13 pairs of macrochromosomes and 12 pairs of microchromosomes, is presented here for first time. Our comparative examination revealed similar cytogenetic features in Emys trinacris and the closely related E. orbicularis, as well as to other previously studied emydid species, demonstrating a low rate of karyotype evolution, as chromosomal rearrangements are rather infrequent in this group of turtles.

Download Full-text

At the Beginning of the End and in the Middle of the Beginning: Structure and Maintenance of Telomeric DNA Repeats and Interstitial Telomeric Sequences

Genes ◽

10.3390/genes10020118 ◽

2019 ◽

Vol 10 (2) ◽

pp. 118 ◽

Cited By ~ 12

Author(s):

Anna Y. Aksenova ◽

Sergei M. Mirkin

Keyword(s):

Genome Stability ◽

Dynamic Properties ◽

Chromosomal Rearrangements ◽

Dna Repeats ◽

Telomeric Dna ◽

Telomeric Sequences ◽

Gross Chromosomal Rearrangements ◽

Interstitial Telomeric Sequences ◽

Chromosomal Fragility ◽

Living Organisms

Tandem DNA repeats derived from the ancestral (TTAGGG)n run were first detected at chromosome ends of the majority of living organisms, hence the name telomeric DNA repeats. Subsequently, it has become clear that telomeric motifs are also present within chromosomes, and they were suitably called interstitial telomeric sequences (ITSs). It is well known that telomeric DNA repeats play a key role in chromosome stability, preventing end-to-end fusions and precluding the recurrent DNA loss during replication. Recent data suggest that ITSs are also important genomic elements as they confer its karyotype plasticity. In fact, ITSs appeared to be among the most unstable microsatellite sequences as they are highly length polymorphic and can trigger chromosomal fragility and gross chromosomal rearrangements. Importantly, mechanisms responsible for their instability appear to be similar to the mechanisms that maintain the length of genuine telomeres. This review compares the mechanisms of maintenance and dynamic properties of telomeric repeats and ITSs and discusses the implications of these dynamics on genome stability.

Download Full-text

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Cytogenetic and Genome Research ◽

10.1159/000478297 ◽

2017 ◽

Vol 152 (2) ◽

pp. 55-64 ◽

Cited By ~ 4

Author(s):

Victor Colomina ◽

Josette Catalan ◽

Janice Britton-Davidian ◽

Frédéric Veyrunes

Keyword(s):

Mammalian Species ◽

Chromosomal Rearrangements ◽

Replication Timing ◽

Pericentromeric Region ◽

Chromosomal Evolution ◽

Telomeric Repeats ◽

Telomeric Sequences ◽

Interstitial Telomeric Sequences ◽

Karyotypic Diversity ◽

The One

Telomeres are ribonucleoprotein structures protecting the physical ends of eukaryotic chromosomes. However, telomeric sequences can also occur at non-terminal regions of chromosomes, forming the so-called interstitial telomeric sequences (ITSs). Some ITSs are considered as relics of past chromosomal rearrangements and as such provide important insights into karyotype evolution. By FISH, we explored the distribution of telomeric motifs in the genome of a complex of mammalian species that has long been recognized for its extraordinary karyotypic diversity: the African pygmy mice. This survey involved 5 species, representing 10 highly diverse karyotypes with or without autosomal and sex-autosome robertsonian (Rb) fusions. The study revealed that in species with an ancestral-like karyotype (i.e., no fusions; Mus mattheyi and M. indutus), only terminal telomeres were observed, whereas in species experiencing intense chromosomal evolution (e.g., M. minutoides, M. musculoides), a large amplification of telomeric repeats was also identified in the pericentromeric region of acrocentrics and most metacentrics. We concluded that (i) the mechanism of Rb fusion in the African pygmy mice is different than the one highlighted in the house mouse; (ii) the intensity of the ITS hybridization signal could be a signature of the age of formation of the Rb fusion; (iii) the large amplification of pericentromeric telomeric sequences in acrocentrics may mediate the formation of Rb fusions, and (iv) the ITSs on the sex-autosome fusion Rb(X.1) may participate to the insulation buffer between the sexual and autosomal arms to prevent X inactivation from spreading and silencing autosomal genes and allow the independent regulation of replication timing of both segments.

Download Full-text

Comparative cytogenetics of four species of Thrichomys (Rodentia: Echimyidae)

Genome ◽

10.1139/gen-2018-0147 ◽

2019 ◽

Vol 62 (1) ◽

pp. 31-41

Author(s):

Naiara Pereira Araújo ◽

Cibele Bonvicino ◽

Marta Svartman

Keyword(s):

Nucleolar Organizer ◽

Interspecific Variation ◽

Northeastern Brazil ◽

Nucleolar Organizer Regions ◽

Comparative Cytogenetics ◽

Telomeric Sequences ◽

Interstitial Telomeric Sequences ◽

Robertsonian Rearrangements ◽

Cytogenetic Analyses

Thrichomys Trouessart, 1880 is a genus of echimyid rodents endemic to South America, distributed from northeastern Brazil to Paraguay and Bolivia. Although all the recognized species of this genus have already been karyotyped, detailed comparative cytogenetic analyses have not been performed yet. We karyologically analyzed four species of Thrichomys from different Brazilian states. Our analyses included GTG- and CBG-banding, silver-staining of the nucleolar organizer regions (Ag-NORs), and fluorescent in situ hybridization (FISH) with telomeric and 45S rDNA probes. Comparative GTG-banding suggested that the interspecific variation may result from Robertsonian rearrangements, pericentric and paracentric inversions, centromere repositioning, and heterochromatin variation. FISH with a telomeric probe showed interspecies variation in interstitial telomeric sequences (ITs) distribution. Our results represent the most complete data on the cytogenetics of Thrichomys reported to date and give an insight into the chromosome evolution of this genus.

Download Full-text

Repetitive Sequence Distribution on Saguinus, Leontocebus and Leontopithecus Tamarins (Platyrrhine, Primates) by Mapping Telomeric (TTAGGG) Motifs and rDNA Loci

Biology ◽

10.3390/biology10090844 ◽

2021 ◽

Vol 10 (9) ◽

pp. 844

Author(s):

Simona Ceraulo ◽

Polina L. Perelman ◽

Sofia Mazzoleni ◽

Michail Rovatsos ◽

Francesca Dumas

Keyword(s):

New World ◽

Chromosomal Rearrangements ◽

Repetitive Sequences ◽

Distinct Group ◽

New World Monkeys ◽

Saguinus Oedipus ◽

Telomeric Sequences ◽

Rdna Loci ◽

Cytogenetic Analyses ◽

Saguinus Geoffroyi

Tamarins are a distinct group of small sized New World monkeys with complex phylogenetic relationships and poorly studied cytogenetic traits. In this study, we applied molecular cytogenetic analyses by fluorescence in situ hybridization with probes specific for telomeric sequences and ribosomal DNA loci after DAPI/CMA3 staining on metaphases from five tamarin species, namely Leontocebus fuscicollis, Leontopithecus rosalia, Saguinus geoffroyi, Saguinus mystax and Saguinus oedipus, with the aim to investigate the distribution of repetitive sequences and their possible role in genome evolution. Our analyses revealed that all five examined species show similar karyotypes, 2n = 46, which differ mainly in the morphology of chromosome pairs 16–17 and 19–22, due to the diverse distribution of rDNA loci, the amplification of telomeric-like sequences, the presence of heterochromatic blocks and/or putative chromosomal rearrangements, such as inversions. The differences in cytogenetic traits between species of tamarins are discussed in a comparative phylogenetic framework, and in addition to data from previous studies, we underline synapomorphies and apomorphisms that appeared during the diversification of this group of New World monkeys.

Download Full-text

A Case of Trisomy 13 Mosaicism Presenting with a Severe Aortic Root Dilatation and Marfanoid Habitus due to an Unpredictable Cytogenetic Mechanism

Cytogenetic and Genome Research ◽

10.1159/000506319 ◽

2020 ◽

Vol 160 (2) ◽

pp. 72-79

Author(s):

Pauline Monin ◽

Nicolas Reynaud ◽

Nadine Hanna ◽

Sophie Dupuis-Girod ◽

Marianne Till ◽

...

Keyword(s):

Aortic Root ◽

Septal Defect ◽

Trisomy 13 ◽

Derivative Chromosome ◽

Homogeneous State ◽

Telomeric Sequences ◽

Healthy Mother ◽

Interstitial Telomeric Sequences ◽

Aortic Root Dilatation ◽

Mosaic Trisomy

In this report, we present a new case of mosaic trisomy 13 with prolonged survival, firstly detected by array-CGH analysis which was carried out because of moderate intellectual disability with postaxial hexadactyly, dermatologic features, ventricular septal defect, bicuspid aortic valve, and aortic dystrophy in a 19-year-old male patient. In a subset of 15% of the cells, the patient carried a derivative chromosome 10 generated by a nonreciprocal (10;13) translocation inherited from his healthy mother who carried the translocation in a balanced and homogeneous state. FISH analyses showed interstitial telomeric sequences at the breakpoints. To our knowledge, this is the second report of a patient with trisomy 13 mosaicism displaying a severe aortic root dilatation. We also discuss the mechanisms which could explain the mosaic state, the most likely one being related to the instability of the interstitial telomere.

Download Full-text

The Breakage-Fusion-Bridge Cycle Producing MLL Amplification in a Case of Myelodysplastic Syndrome

Journal of Cancer Research ◽

10.1155/2013/452809 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6

Author(s):

Lan Ta ◽

Adrian Zordan ◽

Bruce Mercer ◽

Lynda J. Campbell ◽

Ruth N. MacKinnon

Keyword(s):

Clonal Evolution ◽

Chromosomal Rearrangements ◽

Ring Chromosome ◽

Derivative Chromosome ◽

Chromosome 11 ◽

Multicolor Fish ◽

Dicentric Chromosomes ◽

Multicolor Banding ◽

Conventional Cytogenetics

Telomere loss may lead to chromosomal instability via the breakage-fusion-bridge (BFB) cycle which can result in genetic amplification and the formation of ring and dicentric chromosomes. This cycle continues until stable chromosomes are formed. The case of a 72-year-old female with refractory anaemia with excess blasts type 2 illustrates these events. Conventional cytogenetics produced a complex karyotype which included unstable abnormalities of chromosomes 11, 12, and 15. Fluorescence in situ hybridization (FISH) analyses including multicolor-FISH (M-FISH) and multicolor-banding (M-BAND) revealed multiple clonal populations with 5 copies of MLL on either a ring chromosome composed entirely of chromosome 11 material or a derivative chromosome composed of chromosomes 11, 12, and 15. The FISH results also clarified the likely evolution of the karyotypic complexity. The simplest cell line contained a dic(12;15) in addition to copy number aberrations that are typical of MDS or AML. As the disease progressed, a ring 11 was formed. Subsequently, the ring 11 appears to have unwound and inserted itself into the dic(12;15) chromosome followed by an inversion of the derivative chromosome, producing a der(11;15;12). Telomeric loss and BFB cycles appear to have played an important role in the chromosomal rearrangements and clonal evolution demonstrated in the karyotype.

Download Full-text

RELATIONSHIP OF TAXA IN THE GENUS MEDICAGO AS REVEALED BY HYBRIDIZATION. I. M. STRIATA × M. LITTORALIS

Canadian Journal of Genetics and Cytology ◽

10.1139/g68-038 ◽

1968 ◽

Vol 10 (2) ◽

pp. 263-275 ◽

Cited By ~ 10

Author(s):

K. Lesins ◽

A. Erac

Keyword(s):

High Mortality ◽

Genetic Factor ◽

Genetic Factors ◽

Chromosomal Rearrangements ◽

Cytoplasmic Factor ◽

Reciprocal Crosses ◽

Gross Chromosomal Rearrangements ◽

Coiling Direction ◽

Chlorophyll Deficiencies ◽

Relationship Of

In crosses between the two taxa Medicago striata Bast, and M. littoralis Rohde a high mortality of gametes and seedlings, and sterility of some plants were noted which were not related to gross chromosomal rearrangements. Although the F1, F2 and F3 generations from reciprocal crosses differed in chlorophyll deficiencies (indicating a cytoplasmic influence) a genic cause became evident from segregations for chlorophyll characters in the F2 and F3. Transference of the cytoplasmic factor by the pollen is indicative.Segregation for pod coiling direction indicated that the character was determined by one or two genetic factors of which the clockwise coiling direction is recessive. The spininess appeared to be determined by one genetic factor, of which the spineless allele is recessive.On the basis of genetic differences (especially on the built-in repulsion systems for normal chlorophyll development of opposite species) the two taxa should be considered two different species.

Download Full-text