Geographical distribution and interpopulation variation in the karyotypes ofMicrotus (Terricola) thomasi(Rodentia, Arvicolidae) in Greece

Giagia‐Athanasopoulou, Eva B.; Stamatopoulos, C.

doi:10.1080/00087114.1997.10797404

Cited by 20 publications

(41 citation statements)

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“…Two alternative hypotheses have been proposed to explain the origin of the subtelocentric X st0 and X st1 chromosomes of 'atticus' from the acrocentric X chromosomes of 'thomasi': a) a pericentric inversion in one acrocentric X chromosome from the karyomorph 'thomasi' (supposed to be X 1 ), followed by heterochromatin amplification; b) a chromosomal translocation on one of the acrocentric 'tho masi' X chromosomes, followed by heterochromatin amplification (Giagia-Athanasopoulou and Stamatopoulos, 1997;Mitsainas et al, 2008). Both hypotheses imply that the short and long arm heterochromatic blocks of 'atticus' subtelocentric X chromosomes have independent origin, and also that the heterochromatic block of the long arm of these chromosomes originated de novo by amplification of repeat sequences.…”

Section: Mth-alu900-con Actggtcaaaccggttta---------------------------mentioning

confidence: 99%

“…The main difference between them concerns the X chromosome morphology, being characterized as acrocentric in 'thomasi' and subtelocentric in 'atticus' (Giagia-Athanasopoulou and Stamatopoulos, 1997). In addition, regarding the sex chromosomes, the C-banding technique has detected remarkable heterochromatin content variability, both within and between Greek populations of the above two karyomorphs.…”

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“…The five more extensively studied karyomorphs vary in diploid chromosome numbers (2n = 44 to 38) and fundamental numbers (FN = 46 to 40) (Giagia and Ondrias, 1973;Giagia, 1985;Giagia-Athanasopoulou et al, 1995;Giagia-Athanasopoulou and Stamatopoulos, 1997). The taxonomic relation between the karyotypic forms 'thomasi' and 'atticus' is not clearly established, in fact they have been classified by various authors as different species or alternatively as conspecific (Stamatopoulos and Ondrias, 1986;Tsekoura et al, 2002;Kornilios et al, 2005).…”

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A new pericentromeric repeated DNA sequence in Microtus thomasi

Acosta

Marchal

Mitsainas

et al. 2009

Cytogenet Genome Res

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Several karyotypic forms have been previously described in populations of the vole species Microtus thomasi from Greece. In particular, the karyomorphs Microtus thomasi ‘thomasi’ and ‘atticus’ differ in X chromosome morphology, being acrocentric and subtelocentric, respectively. Furthermore, remarkable heterochromatin content variability has been described in sex chromosomes of both karyomorphs. Genomic DNA digestion with AluI allowed us to clone an 884 bp long repeated DNA sequence (Mth-Alu900) from the karyomorph M. thomasi ‘atticus’. This repeated DNA is AT rich and seems to be organized mainly as a dimer of the 884-bp unit, which presents three simple repeats (CAAAT, CAGAT and CAGAC) that constitute 80% of the total unit length. This repeated DNA is exclusive to M. thomasi, since it is absent from the genome of other studied Arvicolinae species. The chromosomal location of Mth-Alu900 was analyzed on M. thomasi ‘thomasi’ and M. thomasi ‘atticus’ karyomorphs, with different sex chromosome constitution. It was mainly located on the pericentromeric heterochromatin of most autosomes and X chromosomes on both karyomorphs. Results are also discussed in relation to karyotypic and sex chromosome variations in M. thomasi. To our knowledge, Mth-Alu900 constitutes a new – the third discovered so far – pericentromeric repeated DNA sequence described in Microtus species.

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Section: Mth-alu900-con Actggtcaaaccggttta---------------------------mentioning

confidence: 99%

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A new pericentromeric repeated DNA sequence in Microtus thomasi

Acosta

Marchal

Mitsainas

et al. 2009

Cytogenet Genome Res

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“…The sibling vole species M. thomasi and M. atticus are remarkable models for studies on the chromosomal evolution, since they probably demonstrate the highest rate of karyotypic diversity among Microtus species. In fact, the 2 species show extensive chromosomal polymorphism, resulting in the description of 9 chromosomal races in M. thomasi : 'thomasi' (2n = [Giagia-Athanasopoulou and Stamatopoulos, 1997;Mitsainas et al, 2009;Rovatsos et al, 2011a;Rovatsos, 2012;Rovatsos and Giagia-Athanasopoulou, 2012]. Among them, the chromosomal races 'thomasi' and 'Evia' are considered the most primitive forms of the species M. thomasi and M. atticus , respectively, with all autosomes and the X chromosomes being acrocentric (2n = 44, FN = 44) [Rovatsos, 2012].…”

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Molecular and Physical Characterization of the Complex Pericentromeric Heterochromatin of the Vole Species Microtus thomasi

Rovatsos

Marchal

Romero-Fernández

et al. 2014

Cytogenet Genome Res

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A new repeated DNA from Microtus thomasi, Mth-Alu2.2, was cloned and characterized and is presented here for the first time. Digestion of genomic DNA from M. thomasi with AluI restriction enzyme revealed a 2.2-kb repetitive DNA sequence with a high AT content (69%). This sequence consists of a tandemly repeated nonanucleotide of the consensus sequence CACAATGTA, which constitutes approximately 93-95% of the total unit length. The location of the Mth-Alu2.2 sequence in the karyotype was determined by FISH, demonstrating strong hybridization signals in the pericentromeric regions of all chromosomes and in the heterochromatin blocks of several X chromosome variants. In addition, the distribution of the 4 pericentromeric repeat sequences Msat-160, Mth-Alu900, Mth-Alu2.2, and interstitial telomeric repeats was analyzed by in situ hybridization in M. thomasi, in order to shed light on the complex composition of the chromosomal pericentromeric regions in this species. The order and organization of these sequences in the pericentromeric regions are conserved, with slight variations in both the degree of overlapping and the amount of each repeated DNA in the chromosomes. Specifically, Mth-Alu2.2 is localized in the terminal regions of the chromosomes, with Msat-160 occupying the immediately inner region, partially intermixed with Mth-Alu2.2. The sequence Mth-Alu900 is found in internal positions below Msat-160, and the interstitial telomeric repeats are located close to the long-arm euchromatin of the chromosomes.

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“…(3) High degree of cytogenetical polytypy and polymorphism (eg liechtensteini-multiplex: Petrov and Zivkovic 1971, Storch and Winking 1977, Graf and Meylan 1980, Brunet-Lecomte and Volobouev 1994savii: Galleni et al 1998;subterraneus-. Sablina et al 1989: thomasi: Giagia-Athanasopoulou andStamatopoulos 1997), sometimes accompanied by remarkable morphological variation.…”

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confidence: 99%