DNA Loss during Robertsonian Fusion in Studies of the Tobacco Mouse

Comings, David E.; Avelino, Evangelita

doi:10.1038/newbio237199a0

Cited by 25 publications

(9 citation statements)

References 7 publications

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“…For further details on this problem and its discussion see White, 1957White, , 1973Kato, 1973;John & Freeman, 1975. It has not been evaluated yet how much DNA becomes lost during the process of centric fusion. Comings & Avelino (1972) have determined by analytical ultracentrifugation that in the case of the mouse Mus poschiavinus, which has 7 metacentrics, probably originated by centric fusion, less than 0.5% of the DNA is lost. Such type of determination would be very difficult to establish in D. silveiraguidoi because of the lack of a similar satellite fraction (Cardoso, personal communication).…”

Section: Pratensismentioning

confidence: 99%

Structure, behaviour and evolution of the chromosomes of Dichroplus silveiraguidoi (Orthoptera: Acrididae)

Sáez

Perez-Mosquera

1977

Genetica

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The organization, behaviour and evolution of somatic and meiotic chromosomes of Dichroplus silveiraguidoi is re-examined. This species constitutes a unique case in Orthoptera, its karyotype being reduced from the ancestral acridioid diploid complement 2n = 23(22 + X) to 2n = 8(6 + XY), the lowest number known in the group. The sex system has also been modified from the primitive XO to the neo-X neo-Y type.New cytogenetical and cytophotometrical information is analyzed from an evolutionary point of view.The reduction mechanisms possibly involved (heterosomal changes by centric and tandem fusion of non homologous chromosomes; structural rearrangements within single chromosomes by pericentric inversions) are discussed.

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Section: Pratensismentioning

confidence: 99%

Structure, behaviour and evolution of the chromosomes of Dichroplus silveiraguidoi (Orthoptera: Acrididae)

Sáez

Perez-Mosquera

1977

Genetica

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“…The short arms (p) of the original telocentric chromosomes, including the proximal telomeres, part of the satellite DNA, and generally one centromere, are all lost. However, this loss of DNA does not significantly alter the total amount of DNA as compared with the standard Mus karyotype [15]. Rb translocation is the most common chromosomal rearrangement in mammals [16] and represents the type of chromosomal change that most effectively contributes to differentiation or speciation of natural populations [17].…”

Section: Introductionmentioning

confidence: 99%

Robertsonian chromosomes and the nuclear architecture of mouse meiotic prophase spermatocytes

et al. 2014

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BackgroundThe nuclear architecture of meiotic prophase spermatocytes is based on higher-order patterns of spatial associations among chromosomal domains from different bivalents. The meiotic nuclear architecture depends on the chromosome characteristics and consequently is prone to modification by chromosomal rearrangements. In this work, we consider Mus domesticus spermatocytes with diploid chromosome number 2n = 40, all telocentric, and investigate a possible modification of the ancestral nuclear architecture due to the emergence of derived Rb chromosomes, which may be present in the homozygous or heterozygous condition.ResultsIn the 2n = 40 spermatocyte nuclei random associations mediated by pericentromeric heterochromatin among the 19 telocentric bivalents ocurr at the nuclear periphery. The observed frequency of associations among them, made distinguishable by specific probes and FISH, seems to be the same for pairs that may or may not form Rb chromosomes. In the homozygote Rb 2n = 24 spermatocytes, associations also mediated by pericentromeric heterochromatin occur mainly between the three telocentric or the eight metacentric bivalents themselves. In heterozygote Rb 2n = 32 spermatocytes all heterochromatin is localized at the nuclear periphery, yet associations are mainly observed among the three telocentric bivalents and between the asynaptic axes of the trivalents.ConclusionsThe Rb chromosomes pose sharp restrictions for interactions in the 2n = 24 and 2n = 32 spermatocytes, as compared to the ample possibilities for interactions between bivalents in the 2n = 40 spermatocytes. Undoubtedly the emergence of Rb chromosomes changes the ancestral nuclear architecture of 2n = 40 spermatocytes since they establish new types of interactions among chromosomal domains, particularly through centromeric and heterochromatic regions at the nuclear periphery among telocentric and at the nuclear center among Rb metacentric ones.

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“…The short arms of the original telocentric chromosomes, including the proximal telomeres, part of the satellite DNA, and frequently 1 centromere, are lost [Comings and Avelino, 1972;Nanda et al, 1995 ;Garagna et al, 2001Garagna et al, , 2002.…”

Section: Robertsonian Chromosomesmentioning

confidence: 99%

Nuclear Architecture of Mouse Spermatocytes: Chromosome Topology, Heterochromatin, and Nucleolus

Berríos

2017

Cytogenet Genome Res

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The nuclear organization of spermatocytes in meiotic prophase I is primarily determined by the synaptic organization of the bivalents that are bound by their telomeres to the nuclear envelope and described as arc-shaped trajectories through the 3D nuclear space. However, over this basic meiotic organization, a spermatocyte nuclear architecture arises that is based on higher-ordered patterns of spatial associations among chromosomal domains from different bivalents that are conditioned by the individual characteristics of chromosomes and the opportunity for interactions between their domains. Consequently, the nuclear architecture is species-specific and prone to modification by chromosomal rearrangements. This model is valid for the localization of any chromosomal domain in the meiotic prophase nucleus. However, constitutive heterochromatin plays a leading role in shaping nuclear territories. Thus, the nuclear localization of nucleoli depends on the position of NORs in nucleolar bivalents, but the association among nucleolar chromosomes mainly depends on the presence of constitutive heterochromatin that does not affect the expression of the ribosomal genes. Constitutive heterochromatin and nucleoli form complex nuclear territories whose distribution in the nuclear space is nonrandom, supporting the hypothesis regarding the existence of a species-specific nuclear architecture in first meiotic prophase spermatocytes.

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DNA Loss during Robertsonian Fusion in Studies of the Tobacco Mouse

Cited by 25 publications

References 7 publications

Structure, behaviour and evolution of the chromosomes of Dichroplus silveiraguidoi (Orthoptera: Acrididae)

Structure, behaviour and evolution of the chromosomes of Dichroplus silveiraguidoi (Orthoptera: Acrididae)

Robertsonian chromosomes and the nuclear architecture of mouse meiotic prophase spermatocytes

Nuclear Architecture of Mouse Spermatocytes: Chromosome Topology, Heterochromatin, and Nucleolus

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