Heterogeneous heterochromatin and size variation in the sex chromosomes of &lt;i&gt;Micvotus cabrera&lt;/i&gt;&lt;i&gt;e&lt;/i&gt;

Burgos, Miguel; Jiménez, Rafael; Olmos, D. M.; Guardia, R. Díaz de la

doi:10.1159/000132510

Cited by 36 publications

(5 citation statements)

References 8 publications

(10 reference statements)

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“…Like in all species of Microtus thus studied, except Microtus kirgisorum ( Mazurok et al 2001 ), NORs have not been detected on the sex chromosomes in the three presently studied taxa. The sex chromosomes of several species of Microtus show complex and heterogeneous heterochromatin, which is indicative of a rapid turnover of repetitive sequences in the genus ( Modi 1987 , Burgos et al 1988 , Marchal et al 2004 ). In the Microtus savii complex, only satellite DNA Msat-160 has been described ( Acosta et al 2010 ).…”

Section: Discussionmentioning

confidence: 99%

Comparative chromosome mapping of the rRNA genes and telomeric repeats in three Italian pine voles of the Microtus savii s.l. complex (Rodentia, Cricetidae)

Gornung

Bezerra

Castiglia

2011

CCG

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The Microtus (Terricola) savii s. l. complex is a group of five species/subspecies of the Italian pine voles, which diverged at different times either with or without chromosomal differentiation. The evidence of chromosomal diversification has so far concerned the shape of the sex chromosomes, especially the X chromosome. Three taxa of the group, Microtus savii savii, Microtus savii nebrodensis, and Microtus savii tolfetanus have identical karyotypes with metacentric X chromosomes. The X chromosomes of Microtus brachycercus and Microtus brachycercus niethammericus are, respectively, subtelocentric and acrocentric in shape. The Microtus savii complex has been long an object of conventional karyological studies, but comparative molecular cytogenetic data were completely missing. Therefore, we conducted a comparative chromosomal mapping of rRNA genes (rDNA) and telomeric repeats in three of the five taxa of the group: Microtus savii savii, Microtus savii nebrodensis, and Microtus brachycercus niethammericus, each of which belongs to a distinct mitochondrial clade.The survey revealed that differentiation of the clades was accompanied by remarkable changes with regard to the number and locations of the rDNA sites. Thus, Microtus savii savii and Microtus savii nebrodensis have especially high numbers of rDNA sites, which are located in the centromeric regions of, correspondingly, 18 and 13 chromosome pairs, whereas Microtus brachycercus niethammericus shows variable (8–10) and heteromorphic rDNA sites on both centromeric and telomeric regions. Interstitial telomeric sites (ITS), which are believed to indicate possible breakpoints of recurring chromosomal rearrangements, are present on the largest biarmed chromosomes and on the metacentric X chromosomes in Microtus savii savii and Microtus savii nebrodensis. These preliminary results are discussed in the context of recent advances in phylogeny of the group, as well as the rDNA genomic organization and X chromosome rearrangements in the genus Microtus.

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Section: Discussionmentioning

confidence: 99%

Comparative chromosome mapping of the rRNA genes and telomeric repeats in three Italian pine voles of the Microtus savii s.l. complex (Rodentia, Cricetidae)

Gornung

Bezerra

Castiglia

2011

CCG

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“…Similar observations have been made in studies on Syrian ham ster autosomes (Popescu and Dipaolo. 1979) and on the X chro mosomes of Microtus carbrerae (Burgos et al, 1988) and the Chinese hamster (Murer-Orlando and Richer, 1983).…”

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confidence: 99%

The chromosomes of tufted deer <i>(Elaphodus cephalophus</i><i>)</i>

Li-ming

Yang²,

Kumamoto³

1991

Cytogenet Genome Res

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Mitotic and meiotic chromosome preparations of the tufted deer (Elaphodus cephalophus) were studied to elucidate the sex-chromosomal polymorphism evidenced by this species. Females had 2n = 46 or 47 chromosomes, whereas males had 2n = 47 or 48 chromosomes. An X;autosome translocation was identified by synaptonemal complex analysis of spermatocytes at pachytene and confirmed by the presence of a trivalent at diakinesis/metaphase I. The present work, in combination with earlier observations by others, indicates that E. cephalophus possesses a varied X-chromosome morphology involving an X;autosome translocation and addition of varying amounts of heterochromatin. It is speculated that sex-chromosome polymorphism may be responsible for the observed differences in diploid chromosome number of tufted deer.

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“…The presence of large blocks of constitutive heterochromatin in both sex chromosomes in M. chrotorrhinus , M. agrestis and M. cabrerae enlarged these chromosomes in comparison to the sex chromosomes of other congeneric species [ 10 , 11 , 15 , 20 ]. Here, we provide a detailed analysis of the composition of the heterochromatic blocks of the X and Y chromosomes in M. chrotorrhinus using chromosome painting and FISH using several repeated DNAs.…”

Section: Discussionmentioning

confidence: 99%

“…In M. chrotorrhinus , the heterochromatic block occupies the entire long arm of the X chromosome, while the small arm is completely euchromatic [ 14 ]. In M. cabrerae , this block occupies the entire short arm and the centromere, and a quarter of the long arm [ 15 , 16 , 17 , 18 ], while in M. agrestis , this block contains the entire long arm, the centromere, and the most proximal quarter of the short arm [ 19 , 20 , 21 ]. The Y chromosomes of the three species are similarly divided into a very long arm composed of constitutive heterochromatin and a very small euchromatic short arm [ 15 , 16 , 20 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Structural and Evolutionary Relationships in the Giant Sex Chromosomes of Three Microtus Species

Lamelas

Arroyo

Fernández

et al. 2018

Genes

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The genus Microtus has high karyotypic diversity. The existence of notable differences in the length of its sex chromosomes contributes to this variation. Variations in size are attributed to the enlargement of their heterochromatin content, which is of such magnitude in some species that they are referred to as “giant sex chromosomes”. Here, we perform an intra- and interspecific analysis of the molecular composition of the heterochromatic blocks in three species with giant sex chromosomes (Microtus chrotorrhinus, M. cabrerae and M. agrestis). Our results show that the heterochromatic content is very similar in both the X and Y chromosomes of M. chrotorrhinus, and that their molecular composition is more closely related to the heterochromatic blocks of M. agrestis than to the sex heterochromatin of M. cabrerae; however, species-specific differences do clearly exist. Interestingly, the euchromatic regions of the X chromosome of all three of these species share a homologous region composed of heterochromatic-related sequences. Our results therefore reinforce the idea that certain similarities in the original organization of these X chromosomes could have facilitated their later enlargement.

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Heterogeneous heterochromatin and size variation in the sex chromosomes of <i>Micvotus cabrera</i><i>e</i>

Cited by 36 publications

References 8 publications

Comparative chromosome mapping of the rRNA genes and telomeric repeats in three Italian pine voles of the Microtus savii s.l. complex (Rodentia, Cricetidae)

Comparative chromosome mapping of the rRNA genes and telomeric repeats in three Italian pine voles of the Microtus savii s.l. complex (Rodentia, Cricetidae)

The chromosomes of tufted deer <i>(Elaphodus cephalophus</i><i>)</i>

Structural and Evolutionary Relationships in the Giant Sex Chromosomes of Three Microtus Species

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