In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes

Nature ◽  
2004 ◽  
Vol 432 (7019) ◽  
pp. 913-917 ◽  
Author(s):  
Frank Grützner ◽  
Willem Rens ◽  
Enkhjargal Tsend-Ayush ◽  
Nisrine El-Mogharbel ◽  
Patricia C. M. O'Brien ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
X Chromosomes

scholarly journals Bisection of the X chromosome disrupts the initiation of chromosome silencing during meiosis in Caenorhabditis elegans

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yisrael Rappaport ◽  
Hanna Achache ◽  
Roni Falk ◽  
Omer Murik ◽  
Oren Ram ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Rna Polymerase Ii ◽  
X Chromosome ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Transcription Analysis ◽  
X Chromosomes ◽  
Unique Character ◽  
Active Transcription ◽  
Heterogametic Sex

AbstractDuring meiosis, gene expression is silenced in aberrantly unsynapsed chromatin and in heterogametic sex chromosomes. Initiation of sex chromosome silencing is disrupted in meiocytes with sex chromosome-autosome translocations. To determine whether this is due to aberrant synapsis or loss of continuity of sex chromosomes, we engineered Caenorhabditis elegans nematodes with non-translocated, bisected X chromosomes. In early meiocytes of mutant males and hermaphrodites, X segments are enriched with euchromatin assembly markers and active RNA polymerase II staining, indicating active transcription. Analysis of RNA-seq data showed that genes from the X chromosome are upregulated in gonads of mutant worms. Contrary to previous models, which predicted that any unsynapsed chromatin is silenced during meiosis, our data indicate that unsynapsed X segments are transcribed. Therefore, our results suggest that sex chromosome chromatin has a unique character that facilitates its meiotic expression when its continuity is lost, regardless of whether or not it is synapsed.

scholarly journals Localization of Male-Specifically Expressed MROS Genes of Silene latifolia by PCR on Flow-Sorted Sex Chromosomes and Autosomes

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1269-1277
Author(s):  
Eduard Kejnovský ◽  
Jan Vrána ◽  
Sachihiro Matsunaga ◽  
Přemysl Souček ◽  
Jiří Široký ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Homology Search ◽  
X Chromosomes ◽  
Dioecious Plants ◽  
Flow Sorting ◽  
Heteromorphic Sex Chromosomes ◽  
Copy Gene ◽  
Melandrium Album ◽  
Pcr Products

Abstract The dioecious white campion Silene latifolia (syn. Melandrium album) has heteromorphic sex chromosomes, XX in females and XY in males, that are larger than the autosomes and enable their separation by flow sorting. The group of MROS genes, the first male-specifically expressed genes in dioecious plants, was recently identified in S. latifolia. To localize the MROS genes, we used the flow-sorted X chromosomes and autosomes as a template for PCR with internal primers. Our results indicate that the MROS3 gene is located in at least two copies tandemly arranged on the X chromosome with additional copy(ies) on the autosome(s), while MROS1, MROS2, and MROS4 are exclusively autosomal. The specificity of PCR products was checked by digestion with a restriction enzyme or reamplification using nested primers. Homology search of databases has shown the presence of five MROS3 homologues in A. thaliana, four of them arranged in two tandems, each consisting of two copies. We conclude that MROS3 is a low-copy gene family, connected with the proper pollen development, which is present not only in dioecious but also in other dicot plant species.

scholarly journals Contingency in the convergent evolution of a regulatory network: Dosage compensation in Drosophila

2018 ◽  
Author(s):  
Doris Bachtrog ◽  
Chris Ellison
Keyword(s):  
Transposable Element ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Binding Sites ◽  
Evolutionary Biology ◽  
De Novo ◽  
Binding Motif ◽  
Sequence Motif ◽  
X Chromosomes ◽  
Msl Complex

The repeatability or predictability of evolution is a central question in evolutionary biology, and most often addressed in experimental evolution studies. Here, we infer how genetically heterogeneous natural systems acquire the same molecular changes, to address how genomic background affects adaptation in natural populations. In particular, we take advantage of independently formed neo-sex chromosomes in Drosophila species that have evolved dosage compensation by co-opting the dosage compensation (MSL) complex, to study the mutational paths that have led to the acquisition of 100s of novel binding sites for the MSL complex in different species. This complex recognizes a conserved 21-bp GA-rich sequence motif that is enriched on the X chromosome, and newly formed X chromosomes recruit the MSL complex by de novo acquisition of this binding motif. We identify recently formed sex chromosomes in the Drosophila repleta and robusta species groups by genome sequencing, and generate genomic occupancy maps of the MSL complex to infer the location of novel binding sites. We find that diverse mutational paths were utilized in each species to evolve 100s of de novo binding motifs along the neo-X, including expansions of microsatellites and transposable element insertions. However, the propensity to utilize a particular mutational path differs between independently formed X chromosomes, and appears to be contingent on genomic properties of that species, such as simple repeat or transposable element density. This establishes the “genomic environment” as an important determinant in predicting the outcome of evolutionary adaptations.

scholarly journals A Syntenic Region Conserved from Fish to Mammalian X Chromosome

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Guijun Guan ◽  
Meisheng Yi ◽  
Tohru Kobayashi ◽  
Yunhan Hong ◽  
Yoshitaka Nagahama
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
Random Amplified Polymorphic Dna ◽  
Comparative Genomic ◽  
X Chromosomes ◽  
Ancestral Origin ◽  
Dna Contents ◽  
Determining Factors ◽  
Unpaired Region ◽  
Syntenic Segment

Sex chromosomes bearing the sex-determining gene initiate development along the male or female pathway, no matter which sex is determined by XY male or ZW female heterogamety. Sex chromosomes originate from ancient autosomes but evolved rapidly after the acquisition of sex-determining factors which are highly divergent between species. In the heterogametic male system (XY system), the X chromosome is relatively evolutionary silent and maintains most of its ancestral genes, in contrast to its Y counterpart that has evolved rapidly and degenerated. Sex in a teleost fish, the Nile tilapia (Oreochromis niloticus), is determined genetically via an XY system, in which an unpaired region is present in the largest chromosome pair. We defined the differences in DNA contents present in this chromosome with a two-color comparative genomic hybridization (CGH) and the random amplified polymorphic DNA (RAPD) approach in XY males. We further identified a syntenic segment within this region that is well conserved in several teleosts. Through comparative genome analysis, this syntenic segment was also shown to be present in mammalian X chromosomes, suggesting a common ancestral origin of vertebrate sex chromosomes.

DIFFERENTIAL DNA REPLICATION IN THE XX AND XY CELLS OF MUSCA DOMESTICA L. OCRA STRAIN

1970 ◽  
Vol 12 (3) ◽  
pp. 461-473 ◽  
Author(s):  
K. Y. Jan ◽  
J. W. Boyes
Keyword(s):  
Dna Replication ◽  
Musca Domestica ◽  
Sex Chromosomes ◽  
Chromosome Length ◽  
Final Part ◽  
X Chromosomes ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Autosomal Pair ◽  
Differential Dna Replication

The karyotype of Musca domestica L. ocra strain, consists of the sex chromosomes and five autosomal pairs. The heteromorphic sex chromosomes are heterochromatic and mitotically unpaired, whereas the autosomes are euchromatic and mitotically paired. All autosomal pairs and both X and Y chromosomes are cytologically recognizable.The relative labelling rate, R (in terms of the number of grains counted per 100 labelled metaphases per μ of chromosome length) for the sex chromosomes and for each autosomal pair was followed from 1.5 hours to 8 hours after H3TdR injection. The pattern of labelling rate was similar for the different autosomal pairs in the XX cells but this pattern for the autosomal pairs in the XY cells, though also similar for the different pairs, differed appreciably from that found in the XX cells. The pattern of the labelling rate for the X chromosomes was similar in the XX and XY cells. Also the pattern of labelling rate for the X and Y chromosomes was similar during the final part of the replication period. The two X chromosomes in the XX cells and the X and Y chromosomes in the XY cells completed labelling later than the autosomes.

scholarly journals Studies on Metatherian Sex Chromosomes. IX. Sex Chromosomes of the Greater Glider (Marsupialia : Petauridae)

1979 ◽  
Vol 32 (3) ◽  
pp. 375 ◽  
Author(s):  
JD Murray ◽  
GM McKay ◽  
GB Sharman
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
National Park ◽  
Secondary Constriction ◽  
X Chromosomes ◽  
Cultured Fibroblasts ◽  
Multiple Sex Chromosomes ◽  
Eastern Australia ◽  
Xy Bivalent ◽  
Secondary Constrictions

The greater glider, currently but incorrectly known as Schoinobates vo/ans, is widely distributed in forested regions in eastern Australia. All animals studied from six different localities had 20 autosomes but there were four chromosomally distinct populations. At Royal National Park, N.S.W., all female greater gliders studied had 22 chromosomes including two large submetacentric X chromosomes with subterminal secondary constrictions in their longer arms. This form of X chromosome occurred also at Bondo State Forest, Myall Lakes and Coff's Harbour, N.S.W., and at Eidsvold, Qld. At Coomooboolaroo, Qld, the X chromosome was also a large submetacentric but a secondary constriction occurred in the shorter arm. Two chromosomally distinct types apparently occur in Royal National Park, one with XY m,ales as in all other populations, and one with XY1Y2 males. Y or Yb but not Y 2, chromosomes were eliminated from the bone marrow in all populations but were present in spermatogonia, primary sperrnatocytes and cultured fibroblasts. Animals from Bondo State Forest had three or more acrocentric or metacentric supernumerary chromosomes. [Other keywords: C-banding, eytotaxonomy, multiple sex chromosomes, XY bivalent.]

Chromosomal homology of wood bison and plains bison

1977 ◽  
Vol 55 (10) ◽  
pp. 1759-1762 ◽  
Author(s):  
K. L. Ying ◽  
D. G. Peden
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Bison Bison ◽  
Banding Patterns ◽  
X Chromosomes ◽  
Chromosomal Homology ◽  
Wood Bison

Karyotypes of wood bison (Bison bison athabascae) and plains bison (Bison bison bison) were studied. Both subspecies were characterized by the same number of chromosomes (2n = 60), acrocentric autosomes, submetacentric X chromosomes, and an acrocentric Y chromosome. G-banding patterns suggest that when comparing wood bison and plains bison, 20 pair plus the sex chromosomes are homologous. Whether or not the remaining nine pair of chromosomes are homologous remains unknown.

Euchromatic domains in plant chromosomes as revealed by H4 histone acetylation and early DNA replication

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 343-350 ◽  
Author(s):  
Boris Vyskot ◽  
Jiri Siroky ◽  
Renata Hladilova ◽  
Nikolai D Belyaev ◽  
Bryan M Turner
Keyword(s):  
Dna Replication ◽  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Histone H4 ◽  
X Chromosomes ◽  
Plant Chromosomes ◽  
Histone H4 Acetylation ◽  
Immunofluorescence Labeling ◽  
Silene Species ◽  
Chromosome Regions

Using specific polyclonal antisera raised against acetylated isoforms of histone H4, we have analyzed their distribution in the dioecious plant Silene latifolia (syn.Melandrium album) possessing heteromorphic sex chromosomes. Our previous studies on this species have shown that one of the two X chromosomes in homogametic female cells is heavily methylated and late replicating, as a possible consequence of dosage compensation. Here we report that there are no detectable differences in intensity and distribution of H4 acetylation between these two X chromosomes. In S. latifolia only distal-subtelomeric chromosome regions, on both the sex chromosomes and autosomes, display strong signals of H4 acetylation at N-terminal lysines 5, 8, and 12. These acetylated domains correspond to the very early replicating distal chromosome regions as revealed by 5-bromodeoxyuridine pulses followed by the indirect immunofluorescence microscopy. The distribution of H4 acetylated at lysine 16 was uniform along the chromosomes. The unique distal-subtelomeric H4 acetylation signals were also observed in three other Silene species (S. vulgaris, S. pendula, andS. chalcedonica), but not in two non-related plant species tested (Allium cepa and Nicotiana tabacum). The presented data as well as our recent studies on the structure of S. latifolia chromosome ends indicate that Silene species possess the specific distal-subtelomeric location of euchromatin, gene-rich regions on chromosomes.Key words: histone H4 acetylation, DNA replication, euchromatin, immunofluorescence labeling, Silene spp.

scholarly journals Dosage compensation in sciarids is achieved by hypertranscription of the single X chromosome in males.

Genetics ◽  
1994 ◽  
Vol 138 (3) ◽  
pp. 787-790
Author(s):  
P R da Cunha ◽  
B Granadino ◽  
A L Perondini ◽  
L Sánchez
Keyword(s):  
X Chromosome ◽  
Dosage Compensation ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
X Chromosomes ◽  
Different Doses

Abstract Dosage compensation refers to the process whereby females and males with different doses of sex chromosomes have similar amounts of products from sex chromosome-linked genes. We analyzed the process of dosage compensation in Sciara ocellaris, Diptera of the suborder Nematocera. By autoradiography and measurements of X-linked rRNA in females (XX) and males (XO), we found that the rate of transcription of the single X chromosome in males is similar to that of the two X chromosomes in females. This, together with the bloated appearance of the X chromosome in males, support the idea that in sciarids dosage compensation is accomplished by hypertranscription of the X chromosome in males.

scholarly journals Studies on Metatherian Sex Chromosomes III. The Use of Tritiated Uridine-induced Chromosome Aberrations to Distinguish Active and Inactive X Chromosomes

1977 ◽  
Vol 30 (2) ◽  
pp. 103 ◽  
Author(s):  
Jennifer A Donald ◽  
DW Cooper
Keyword(s):  
X Chromosome ◽  
Sex Chromosomes ◽  
Chromosome Aberrations ◽  
X Inactivation ◽  
Facultative Heterochromatin ◽  
Hybrid Female ◽  
X Chromosomes ◽  
Toxicity Effect ◽  
Red Kangaroo ◽  
Chromosome Regions

The paternal X inactivation system of kangaroos has been investigated in this study by using tritiated uridine-induced chromosome aberrations to distinguish the active from the inactive X. Previous work in eutherian mammals has demonstrated that constitutive heterochromatic chromosome regions are less susceptible to breakage by tritiated uri dine than euchromatic regions. The results of a comparison between the paternal X chromosome of a wallaroo x red kangaroo hybrid female and the two X chromosomes of a red kangaroo female suggested that the facultative heterochromatin of the X is also less susceptible to breakage by this treatment. However there were significantly more breaks of the paternal X in fibroblasts than in lymphocytes of the hybrid female, which agrees with biochemical findings suggesting activation of the paternal X in fibroblasts. Our results strengthen the suggestion of other workers that the reduced number of aberrations in heterochromatin occurs because such breaks occur principally when the DNA and labelled RNA are in apposition during transcription. Some evidence was found of an apparent toxicity effect of the tritiated uridine solution on the cells.

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