scholarly journals African pygmy mouse upgrades mitochondria to compensate for size

2020 ◽  
Vol 223 (5) ◽  
pp. jeb223693
Author(s):  
Kathryn Knight
Keyword(s):  
African Pygmy Mouse

scholarly journals Meiotic Behavior of Achiasmate Sex Chromosomes in the African Pygmy Mouse Mus mattheyi Offers New Insights into the Evolution of Sex Chromosome Pairing and Segregation in Mammals

Genes ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1434
Author(s):  
Ana Gil-Fernández ◽  
Marta Ribagorda ◽  
Marta Martín-Ruiz ◽  
Pablo López-Jiménez ◽  
Tamara Laguna ◽  
...  
Keyword(s):  
Dna Repair ◽  
Y Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Mammalian Species ◽  
Evolutionary Process ◽  
Small Region ◽  
Pseudoautosomal Region ◽  
Evolution Of Sex ◽  
African Pygmy Mouse

X and Y chromosomes in mammals are different in size and gene content due to an evolutionary process of differentiation and degeneration of the Y chromosome. Nevertheless, these chromosomes usually share a small region of homology, the pseudoautosomal region (PAR), which allows them to perform a partial synapsis and undergo reciprocal recombination during meiosis, which ensures their segregation. However, in some mammalian species the PAR has been lost, which challenges the pairing and segregation of sex chromosomes in meiosis. The African pygmy mouse Mus mattheyi shows completely differentiated sex chromosomes, representing an uncommon evolutionary situation among mouse species. We have performed a detailed analysis of the location of proteins involved in synaptonemal complex assembly (SYCP3), recombination (RPA, RAD51 and MLH1) and sex chromosome inactivation (γH2AX) in this species. We found that neither synapsis nor chiasmata are found between sex chromosomes and their pairing is notably delayed compared to autosomes. Interestingly, the Y chromosome only incorporates RPA and RAD51 in a reduced fraction of spermatocytes, indicating a particular DNA repair dynamic on this chromosome. The analysis of segregation revealed that sex chromosomes are associated until metaphase-I just by a chromatin contact. Unexpectedly, both sex chromosomes remain labelled with γH2AX during first meiotic division. This chromatin contact is probably enough to maintain sex chromosome association up to anaphase-I and, therefore, could be relevant to ensure their reductional segregation. The results presented suggest that the regulation of both DNA repair and epigenetic modifications in the sex chromosomes can have a great impact on the divergence of sex chromosomes and their proper transmission, widening our understanding on the relationship between meiosis and the evolution of sex chromosomes in mammals.

scholarly journals XY FEMALES DO BETTER THAN THE XX IN THE AFRICAN PYGMY MOUSE,MUS MINUTOIDES

Evolution ◽  
2014 ◽  
Vol 68 (7) ◽  
pp. 2119-2127 ◽  
Author(s):  
Paul A. Saunders ◽  
Julie Perez ◽  
Massilva Rahmoun ◽  
Ophélie Ronce ◽  
Pierre-André Crochet ◽  
...  
Keyword(s):  
African Pygmy Mouse ◽  
Mus Minutoides ◽  
Better Than

scholarly journals Meiosis reveals the early steps in the evolution of a neo-XY sex chromosome pair in the African pygmy mouse Mus minutoides

2020 ◽  
Author(s):  
Ana Gil-Fernández ◽  
Paul A. Saunders ◽  
Marta Martín-Ruiz ◽  
Marta Ribagorda ◽  
Pablo López-Jiménez ◽  
...  
Keyword(s):  
Dna Repair ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Sex Chromosome Evolution ◽  
Chromosome Differentiation ◽  
Large Segment ◽  
Y Chromosomes ◽  
African Pygmy Mouse ◽  
Mus Minutoides

ABSTRACTSex chromosomes of eutherian mammals are highly different in size and gene content, and share only a small region of homology (pseudoautosomal region, PAR). They are thought to have evolved through an addition-attrition cycle involving the addition of autosomal segments to sex chromosomes and their subsequent differentiation. The events that drive this process are difficult to investigate because sex chromosomes in most mammals are at a very advanced stage of differentiation. Here, we have taken advantage of a recent translocation of an autosome to both sex chromosomes in the African pygmy mouse Mus minutoides, which has restored a large segment of homology (neo-PAR). By studying meiotic sex chromosome behavior and identifying fully sex-linked genetic markers in the neo-PAR, we demonstrate that this region shows unequivocal signs of early sex-differentiation. First, synapsis and resolution of DNA damage intermediates are delayed in the neo-PAR during meiosis. Second, recombination is suppressed in a large portion of the neo-PAR. However, the inactivation process that characterizes sex chromosomes during meiosis does not extend to this region. Finally, the sex chromosomes show a dual mechanism of association at metaphase-I that involves the formation of a chiasma in the neo-PAR and the preservation of an ancestral achiasmate mode of association in the non-homologous segments. We show that the study of meiosis is crucial to apprehend the onset of sex chromosome differentiation, as it introduces structural and functional constrains to sex chromosome evolution. Synapsis and DNA repair dynamics are the first processes affected in the incipient differentiation of X and Y chromosomes, and they may be involved in accelerating their evolution. This provides one of the very first reports of early steps in neo-sex chromosome differentiation in mammals, and for the first time a cellular framework for the addition-attrition model of sex chromosome evolution.AUTHOR SUMMARYThe early steps in the evolution of sex chromosomes are particularly difficult to study. Cessation of recombination around the sex-determining locus is thought to initiate the differentiation of sex chromosomes. Several studies have investigated this process from a genetic point of view. However, the cellular context in which recombination arrest occurs has not been considered as an important factor. In this report, we show that meiosis, the cellular division in which pairing and recombination between chromosomes takes place, can affect the incipient differentiation of X and Y chromosomes. Combining cytogenetic and genomic approaches, we found that in the African pygmy mouse Mus minutoides, which has recently undergone a sex chromosome-autosome fusion, synapsis and DNA repair dynamics are altered along the newly added region of the sex chromosomes, likely interfering with recombination and thus contributing to the genetic isolation of a large segment of the Y chromosome. Therefore, the cellular events that occur during meiosis are crucial to understand the very early stages of sex chromosome differentiation. This can help to explain why sex chromosomes evolve very fast in some organisms while in others they have barely changed for million years.

scholarly journals The growth hormone gene has evolved independently in African Pygmy Mouse Mus minutoides

2021 ◽  
Author(s):  
Sumito Matsuya ◽  
Hiroyuki Imai ◽  
Yasuo Kiso ◽  
Ken Takeshi Kusakabe ◽  
Kiyoshi Kano
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Amino Acid Sequences ◽  
Growth Hormone Gene ◽  
Neighbor Joining ◽  
Coding Region ◽  
Transcriptional Regulatory ◽  
African Pygmy Mouse ◽  
Mus Minutoides ◽  
Gene Expression Levels

AbstractMus minutoides (the African pygmy mouse) is one of the smallest mammals. We determined the nucleotide sequence of the growth hormone (Gh) gene and the sequence of the putative coding region in M. minutoides, where is predicted to be distinct in the functional and transcriptional regulatory regions between M. minutoides and Mus musculus (the House mouse). To investigate the evolutionary characteristics of Gh in M. minutoides, we constructed a phylogenetic tree based on the putative amino acid sequences of Gh in M. musculus and mammals by neighbor-joining method, suggesting that Gh diverged relatively earlier than other Mus genus and may have evolved independently in M. minutoides. Furthermore, analysis of Gh gene expression levels showed a tendency to be higher in M. minutoides than in M. musculus. Our results suggest that Gh may have evolved independently in M. minutoides and may have different functions and signaling in Mus genus.

A new cytotype of the African pygmy mouse Mus minutoides in Eastern Africa. Implications for the evolution of sex-autosome translocations

2014 ◽  
Vol 22 (4) ◽  
pp. 533-543 ◽  
Author(s):  
F. Veyrunes ◽  
J. Perez ◽  
B. Borremans ◽  
S. Gryseels ◽  
L. R. Richards ◽  
...  
Keyword(s):  
Eastern Africa ◽  
Evolution Of Sex ◽  
African Pygmy Mouse ◽  
Mus Minutoides

scholarly journals A novel sex determination system in a close relative of the house mouse

2009 ◽  
Vol 277 (1684) ◽  
pp. 1049-1056 ◽  
Author(s):  
Frederic Veyrunes ◽  
Pascale Chevret ◽  
Josette Catalan ◽  
Riccardo Castiglia ◽  
Johan Watson ◽  
...  
Keyword(s):  
Sex Determination ◽  
House Mouse ◽  
Sex Chromosome ◽  
High Mobility ◽  
Close Relative ◽  
Mammal Species ◽  
Determination System ◽  
African Pygmy Mouse ◽  
Mus Minutoides ◽  
Sex Determination System

Therian mammals have an extremely conserved XX/XY sex determination system. A limited number of mammal species have, however, evolved to escape convention and present aberrant sex chromosome complements. In this study, we identified a new case of atypical sex determination in the African pygmy mouse Mus minutoides , a close evolutionary relative of the house mouse. The pygmy mouse is characterized by a very high proportion of XY females (74%, n = 27) from geographically widespread Southern and Eastern African populations. Sequencing of the high mobility group domain of the mammalian sex determining gene Sry , and karyological analyses using fluorescence in situ hybridization and G-banding data, suggest that the sex reversal is most probably not owing to a mutation of Sry , but rather to a chromosomal rearrangement on the X chromosome. In effect, two morphologically different X chromosomes were identified, one of which, designated X*, is invariably associated with sex-reversed females. The asterisk designates the still unknown mutation converting X*Y individuals into females. Although relatively still unexplored, such an atypical sex chromosome system offers a unique opportunity to unravel new genetic interactions involved in the initiation of sex determination in mammals.

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