Sequential meiotic prophase development in the pubertal Indian pygmy field mouse: Synaptic progression of the XY chromosomes, autosomal heterochromatin, and pericentric inversions

Genome ◽  
2000 ◽  
Vol 43 (1) ◽  
pp. 172-180 ◽  
Author(s):  
Amit Bardhan ◽  
T Sharma
Keyword(s):  
Meiotic Prophase ◽  
Pericentric Inversion ◽  
Chiasma Formation ◽  
Subsequent Paper ◽  
Y Chromosomes ◽  
Xy Bivalent ◽  
Mus Terricolor ◽  
Chromosomal Changes ◽  
Meiotic Synapsis ◽  
Chromosomal Mutations

Sequential meiotic prophase development has been followed in the pubertal male pygmy mouse Mus terricolor, with the objective to identify early meiotic prophase stages. The pygmy mouse differs from the common mouse by having large heterochromatic blocks in the X and Y chromosomes. These mice also show various chromosomal mutations; for example, fixed variations of autosomal short arms heterochromatin among different chromosomal species and pericentric inversion polymorphism. Identification of prophase stages was crucial to analyzing effects of heterozygosity for these chromosomal changes on the process of homologous synapsis. Here we describe identification of the prophase stages in M. terricolor, especially the pachytene substages, on the basis of morphology of the XY bivalent. Based on this substaging, we show delayed pairing of the heterochromatic short arms, which may be the reason for their lack of chiasmata. The identification of precise pachytene substages also reveals an early occurrence of "synaptic adjustment" in the pericentric inversion heterobivalents, a mechanism that would prevent chiasma formation in the inverted segment and thereby would abate adverse effects of such heterozygosity. The identification of pachytene substages would serve as the basis to analyze the nature of synaptic anomalies met in M. terricolor hybrids (which will be the basis of a subsequent paper). Key words: Mus terricolor, meiotic synapsis, sex chromosomes, pericentric inversion, heterochromatin.

Morphological and temporal sequence of meiotic prophase development at puberty in the male mouse

1984 ◽  
Vol 65 (1) ◽  
pp. 249-263
Author(s):  
P. Goetz ◽  
A.C. Chandley ◽  
R.M. Speed
Keyword(s):  
Synaptonemal Complex ◽  
Adult Male ◽  
Meiotic Prophase ◽  
Male Mouse ◽  
Late Pachytene ◽  
Diplotene Stage ◽  
Y Chromosomes ◽  
Correct Sequence ◽  
Xy Bivalent ◽  
Morphological Detail

The correct sequence of meiotic prophase development in the male mouse has been established by the use of pubertal males. The first wave of spermatogenesis at this time provides a unique opportunity to study progressive meiotic development in a direct way. Air-dried and micro-spread analyses have been carried out. Temporal and morphological progression at this time is entirely consistent with that occurring in the later waves of meiosis of the adult male. Morphological detail shows delayed pairing of the X and Y chromosomes relative to the autosomes. The longest XY synaptonemal complex is seen in early pachytene cells, occupying up to 72% of the length of the Y and 22% of the length of the X axis. By late pachytene, end-to-end pairing in the XY bivalent is established, the autosomal axes remaining fully paired. Desynapsis of the autosomes commences at early diplotene. A ‘diffuse’ diplotene stage in the male, comparable to the dictyate stage of the female, could not be found. Marked lengthening of the XY and autosomal axes did, however, occur through the diplotene stage.

Pattern of X-Y chromosome pairing in the Taiwan vole, Microtus kikuchii

Genome ◽  
2001 ◽  
Vol 44 (1) ◽  
pp. 27-31 ◽  
Author(s):  
K Mekada ◽  
M Harada ◽  
L K Lin ◽  
K Koyasu ◽  
P M Borodin ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Sex Chromosomes ◽  
Meiotic Prophase ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Nucleolar Organizer ◽  
The Other ◽  
Banding Patterns ◽  
Y Chromosomes

Pairing of X and Y chromosomes at meiotic prophase and the G- and C-banding patterns and nucleolar organizer region (NOR) distribution were analyzed in Microtus kikuchii. M. kikuchii is closely related to M. oeconomus and M. montebelli, karyologically and systematically. The formation of a synaptonemal complex between the X and Y chromosomes at pachytene and end-to-end association at diakinesis – metaphase I are only observed in three species in the genus Microtus; M. kikuchii, M. oeconomus, and M. montebelli. All the other species that have been studied so far have had asynaptic X–Y chromosomes. These data confirm that M. kikuchii, M. oeconomus, and M. montebelli are very closely related, and support the separation of asynaptic and synaptic groups on the phylogenetic tree.Key words: Microtus kikuchii, Microtus phylogeny, karyotype, synaptic sex chromosomes, synaptonemal complex.

Persistence of two Y chromosomes through meiotic prophase and metaphase I in an XYY man

1991 ◽  
Vol 87 (4) ◽  
Author(s):  
R.M. Speed ◽  
M.J.W. Faed ◽  
P.J. Batstone ◽  
K. Baxby ◽  
W. Barnetson
Keyword(s):  
Meiotic Prophase ◽  
Y Chromosomes ◽  
Metaphase I

Chromosome banding analysis of two shrews of the cinereus group: Sorex haydeni and Sorex cinereus (Insectivora, Soricidae)

1994 ◽  
Vol 72 (5) ◽  
pp. 958-964 ◽  
Author(s):  
Vitaly T. Volobouev ◽  
Constantinus G. van Zyll de Jong
Keyword(s):  
Pericentric Inversion ◽  
Chromosome Banding ◽  
Morphological Characters ◽  
Y Chromosomes ◽  
Banding Analysis ◽  
Chromosome Banding Analysis ◽  
Sorex Cinereus ◽  
The Status ◽  
First Time ◽  
Independent Species

The chromosomes of Sorex haydeni are described for the first time and their banding pattern (R- and C-bands) compared with that of Sorex cinereus. The karyotype of S. haydeni differs from that of S. cinereus in its diploid (64 vs. 66) and fundamental numbers (66 vs. 70). These differences are the result of one tandem translocation and one pericentric inversion. The size and form of the Y chromosomes are also quite different in these taxa. The karyotypic differences strongly support the status of independent species, proposed for these taxa earlier on the basis of gross morphological characters.

Elimination of multivalents during meiotic prophase in Scilla autumnalis. I. Diploid and triploid

Genome ◽  
1988 ◽  
Vol 30 (6) ◽  
pp. 930-939 ◽  
Author(s):  
J. White ◽  
G. Jenkins ◽  
J. S. Parker
Keyword(s):  
Meiotic Prophase ◽  
Three Dimensional ◽  
Low Frequency ◽  
Chiasma Formation ◽  
Root Tip ◽  
Synaptonemal Complexes ◽  
Dimensional Reconstruction ◽  
Scilla Autumnalis ◽  
Surface Spreading ◽  
Pairing Behaviour

The ultrastructure and pairing behaviour of the chromosomes of two diploid cytotypes and a triploid of Scilla autumnalis were investigated using the techniques of three-dimensional reconstruction from serial electron micrographs and whole-mount surface spreading of synaptonemal complexes. The diploids, designated AA and B7B7, have karyotypes that are virtually identical in appearance at mitotic metaphase but differ in length by 47% and in DNA content by 66%. All the chromosomes were identified during meiotic prophase in both diploids, enabling construction of accurate karyotypes, which were the same as those derived from root tip metaphases. Chromosome pairing was largely regular with very few structural chromosome rearrangements. These two observations permitted confident interpretations of multivalent configurations observed in polyploids containing multiples of the A and B7 genomes. In the triploid (AB7B7) during meiotic prophase lateral components are associated in groups of three, either as trivalents with several exchanges of pairing partners, or as bivalents and univalents in close alignment. The overall difference in length between A and B7 chromosomes is close to expected, but varies to some degree depending on the extent of pairing between the two chromosome types. Most of the synaptonemal complexes between A and B7 homoeologues are ineffective in terms of chiasma formation, as revealed by the low frequency of multivalents and heteromorphic bivalents at metaphase I. In other words, there is an elimination of multivalents during meiotic prophase in the triploid.Key words: Scilla autumnalis, synaptonemal complex, multivalents, elimination.

scholarly journals Hexavalents in spermatocytes of Robertsonian heterozygotes between Mus m. domesticus 2n=26 from the Vulcano and Lipari Islands (Aeolian Archipelago, Italy)

2018 ◽  
Author(s):  
Soledad Berríos ◽  
Raúl Fernández-Donoso ◽  
Jesús Page ◽  
Eliana Ayarza ◽  
Ernesto Capanna ◽  
...  
Keyword(s):  
X Chromosome ◽  
Nuclear Architecture ◽  
Mus Musculus Domesticus ◽  
Open Chain ◽  
Telocentric Chromosome ◽  
Telocentric Chromosomes ◽  
Xy Bivalent ◽  
Chromosomal Changes ◽  
A Chain ◽  
Pachytene Spermatocytes

The size and shape of the chromosomes, as well as the chromosomal domains that compose them, are determinants in the distribution and interaction between the bivalents within the nucleus of spermatocytes in prophase I of meiosis. Thus the nuclear architecture characteristic of the karyotype of a species can be modified by chromosomal changes such as Rb chromosomes. In this study we analysed the meiotic prophase nuclear organization of the heterozygous spermatocytes from Mus musculus domesticus 2n=26, and the synaptic configuration of the hexavalent formed by the dependent Rb chromosomes Rbs 6.16, 16.10, 10.15, 15.17 and the telocentric chromosomes 6 and 17. Spreads of 88 pachytene spermatocytes from two males were studied and in all of them five metacentric bivalents, four telocentric bivalents, one hexavalent and the XY bivalent were observed. About 48% of the hexavalents formed a chain or a ring of synapsed chromosomes, the latter closed by synapsis between the short arms of telocentric chromosomes 6 and 17.  About 52% of hexavalents formed an open chain of 10 synapsed chromosomal arms belonging to 6 chromosomes.  In about half of the unsynapsed hexavalents one of the telocentric chromosome short arms appears associated with the X chromosome single axis, which was otherwise normally paired with the Y chromosome.  The cluster of pericentromeric heterochromatin mostly determines the hexavalent’s nuclear configuration, dragging the centromeric regions and all the chromosomes towards the nuclear envelope similar to an association of five telocentric bivalents. These reiterated encounters between these chromosomes restrict the interactions with other chromosomal domains and might favour eventual rearrangements within the metacentric, telocentric or hexavalent chromosome subsets. The unsynapsed short arms of telocentric chromosomes frequently bound to the single axis of the X chromosome could further complicate the already complex segregation of hexavalent chromosomes.

Genetic variability in Muscari comosum L. (Liliaceae). II. Characterization and effects of the polymorphic variants of chromosome 2 on chiasmata formation

Genome ◽  
1987 ◽  
Vol 29 (5) ◽  
pp. 695-701
Author(s):  
C. Ruiz Rejon ◽  
R. Lozano ◽  
M. Ruiz Rejon
Keyword(s):  
Genetic Variability ◽  
Key Words ◽  
Pericentric Inversion ◽  
Chromosomal Polymorphism ◽  
Chiasma Formation ◽  
The Other ◽  
Chromosome 2 ◽  
Polymorphic Variants ◽  
Insertional Translocation ◽  
Normal Pairing

Muscari comosum L. (Liliaceae) displays a striking chromosomal polymorphism in the second largest chromosome. This polymorphism involves four cosmopolitan types. Two of these are shorter than the other two homologues. One of these is submetacentric (SSM) and the other is subtelocentric (SST). The two longer types also include a submetacentric (LSM) and a subtelocentric (LST) morph. Each of the two submetacentric chromosomes has one interstitial C-band in the short arm and each of the two subtelocentric morphs has an interstitial C-band in the long arm. The change of position of this interstitial C-band is most easily explained by a pericentric inversion. Furthermore, all four types of chromosome 2 have a centromeric C-band, while the two subtelocentrics have an additional terminal C-band in the long arm. The variability in the size of the second chromosome is most likely the consequence of an unequal interchange or an insertional translocation. The meiotic behaviour of the chromosome 2 bivalents in individuals heterozygous for the pericentric inversion is characterized by normal pairing between homologues with no inversion loops, though asynapsis was present in some meiocytes. Chiasmata are absent in two regions of chromosome 2 bivalents in these heterozygotes in which they regularly form in both classes of homozygotes. In individuals heterozygous for the long morphs of chromosome 2 the bivalents again showed normal pairing at pachytene, with chiasmata again absent in some regions in which they normally form. The net result is that homozygotes have significantly higher chiasmata frequencies than hterozygotes. Key words: genetic variability, chiasma formation, Muscari.

Comparative analysis of female and male meiosis in three meiotic mutants of tomato

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 879-886 ◽  
Author(s):  
Francis W. J. Havekes ◽  
J. Hans de Jong ◽  
Christa Heyting
Keyword(s):  
Comparative Analysis ◽  
Chromosome Pairing ◽  
Meiotic Prophase ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Male Meiosis ◽  
Wild Type ◽  
Female Meiosis ◽  
Similar Reduction ◽  
Meiotic Mutants

Female meiosis was analysed in squash preparations of ovules from three meiotic mutants and wild-type plants of tomato. In the completely asynaptic mutant as6, chromosome pairing and chiasma formation were virtually absent in both sexes. In the partially asynaptic mutant asb, with intermediate levels of chromosome pairing at pachytene, there were a higher number of chiasmate chromosome arms in female meiosis than in male meiosis, whereas in the desynaptic mutant as5 there were normal levels of chromosome pairing at pachytene and a similar reduction in chiasma frequency in the two sexes. In wild-type tomato, we found slightly higher numbers of chiasmate chromosome arms in female meiosis than in male meiosis. We propose that the higher female chiasma frequencies in mutant asb and wild-type tomato result from a longer duration of female meiotic prophase. This would allow chromosomes more time to pair and recombine. It is possible that a longer duration of prophase I does not affect mutants as5 and as6, either because the meiotic defect acts before the pairing process begins (in as6) or because it acts at a later stage and involves chiasma maintenance (in as5).Key words: female meiosis, tomato, chiasma, mutant.

scholarly journals The behavior of the X- and Y-chromosomes in the oocyte during meiotic prophase in the B6.YTIR sex-reversed mouse ovary

Reproduction ◽  
2008 ◽  
Vol 135 (2) ◽  
pp. 241-252 ◽  
Author(s):  
Michelle Alton ◽  
Mau Pan Lau ◽  
Michele Villemure ◽  
Teruko Taketo
Keyword(s):  
Y Chromosome ◽  
Germ Cells ◽  
Sex Chromosomes ◽  
Meiotic Prophase ◽  
Transcriptional Repression ◽  
Transcriptional Activity ◽  
Sex Chromosome ◽  
Nuclear Antigen ◽  
Mouse Ovary ◽  
Y Chromosomes

Sexual differentiation of the germ cells follows gonadal differentiation, which is determined by the presence or the absence of the Y-chromosome. Consequently, oogenesis and spermatogenesis take place in the germ cells with XX and XY sex chromosomal compositions respectively. It is unclear how sexual dimorphic regulation of meiosis is associated with the sex-chromosomal composition. In the present study, we examined the behavior of the sex chromosomes in the oocytes of the B6.YTIRsex-reversed female mouse, in comparison with XO and XX females. As the sex chromosomes fail to pair in both XY and XO oocytes during meiotic prophase, we anticipated that the pairing failure may lead to excessive oocyte loss. However, the total number of germ cells, identified by immunolabeling of germ cell nuclear antigen 1 (GCNA1), did not differ between XY and XX ovaries or XO and XX ovaries up to the day of delivery. The progression of meiotic prophase, assessed by immunolabeling of synaptonemal complex components, was also similar between the two genotypes of ovaries. These observations suggest that the failure in sex-chromosome pairing is not sufficient to cause oocyte loss. On the other hand, labeling of phosphorylated histone γH2AX, known to be associated with asynapsis and transcriptional repression, was seen over the X-chromosome but not over the Y-chromosome in the majority of XY oocytes at the pachytene stage. For comparison, γH2AX labeling was seen only in the minority of XX oocytes at the same stage. We speculate that the transcriptional activity of sex chromosomes in the XY oocyte may be incompatible with ooplasmic maturation.

Sign in / Sign up

Export Citation Format

Share Document