scholarly journals Germline Exclusion of Cks1 in the Mouse Reveals a Metaphase I Role for Cks Proteins in Male and Female Meiosis

Cell Cycle ◽  
2003 ◽  
Vol 2 (4) ◽  
pp. 274-275 ◽  
Author(s):  
Peter J. Donovan ◽  
Steven I. Reed
Reproduction ◽  
2000 ◽  
pp. 165-171 ◽  
Author(s):  
Z Polanski

Univalents at the first meiotic metaphase in mouse spermatocytes occur mainly in the XY pair, making it difficult to compare the amounts of univalency in males and females. In this study, the amounts of autosomal univalency in male and female meiosis were compared using the model strain CBA-T6, in which univalency of the small marker autosome pair T6 has been shown to occur very frequently in spermatocytes. Mice from inbred CBA and DBA strains were also analysed. The total frequencies of univalency (sex chromosomes plus autosomes) in metaphase I spermatocytes were 45.6% in CBA, 36.9% in CBA-T6, and 37.3% in DBA males. The aneuploidy in metaphase II spermatocytes ranged from 1.4 to 3% in these strains, which was in agreement with previous findings that most primary spermatocytes with abnormal chromosome configurations are arrested in their development before metaphase II. In the CBA-T6 strain, autosomal univalency at metaphase I mostly involved chromosome pair T6; however, its frequency differed significantly between the sexes, amounting to 18.9% in spermatocytes and 4.3% in oocytes. In the CBA strain, autosomal univalents at metaphase I were seen in 7.7% of the spermatocytes and 1.4% of the oocytes and, in DBA mice, in 4.9% of the spermatocytes and 3.8% of the oocytes. However, in DBA oocytes, when univalency occurred it usually concerned a greater number of bivalents in one cell (range: 2-19 disjoined bivalents), a phenomenon very rare in males of this strain. This study shows that univalent formation differs between the male and female types of meiosis.


2003 ◽  
Vol 67 (1) ◽  
pp. 116-126 ◽  
Author(s):  
Christian Olesen ◽  
Morten Møller ◽  
Anne Grete Byskov

Chromosoma ◽  
1997 ◽  
Vol 106 (7) ◽  
pp. 435-445 ◽  
Author(s):  
Tadzunu Suzuki ◽  
Noriko Ide ◽  
Ichiro Tanaka

CYTOLOGIA ◽  
2004 ◽  
Vol 69 (3) ◽  
pp. 285-289 ◽  
Author(s):  
Kuldeep K. Koul ◽  
Ranjna Nagpal

For technical reasons studies of chiasma frequency and distribution, and hence of intrachromosomal recombination, have mostly been confined to male meiosis. However, there is now sufficient comparative data on male and female meiosis, in both plants and animals, to show that the extent of intra-chromosomal recombination in some organisms may be much the same on the female as on the male side, whereas other organisms show extreme sexual divergence in this regard. The evolutionary significance of such diversity remains enigmatic


Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 121-130 ◽  
Author(s):  
E. Jongedijk ◽  
R. C. B. Hutten ◽  
J. M. A. S. A. van der Wolk ◽  
S. I. J. Schuurmans Stekhoven

By applying half-tetrad analysis to segregating tetraploid progeny that had been raised from 2x–4x and 2x–2x crosses, five marker loci (ym, y, Got-1, Got-2, and ds-1) were mapped to their respective centromeres in male and female meiosis of both normal synaptic and desynaptic (ds-1ds-1) diploid potato clones. Significant sex differences in genetic recombination for these loci did not occur in either normal plants or desynaptic mutants, which suggests that genetic exchange in both the sexes is governed by the same control system. In desynaptic mutants a severe reduction in crossing-over was observed for ym and.y (83.7 an 90.0% reduction, respectively), whereas recombination rates for Got-2 appeared to have systematically, although not significantly, increased. The ds-1 gene was concluded to substantially reduce the overall chiasma frequency and to differentially alter chiasma distribution along individual chromosomes. Based on segregation ratios in progeny from different types of testcrosses, first division restitution (FDR) and second division restitution (SDR) 2n gametes formed by normal synaptic plants were estimated to transmit on average about 82.7 and 36.1 %, respectively, of the parental heterozygosity to tetraploids. With desynapsis the average amount of heterozygosity transmitted by FDR 2n gametes amounted to 94.1%. SDR 2n gametes from desynaptic mutants are sterile as a result of aneuploidy. The ds-1 gene was demonstrated to particularly enhance the ability of FDR 2n gametes to preserve the genetic constitution of diploid parental clones with a minimum amount of reassortment. The potential value and limitations of the ds-1 gene for the production of true potato seed varieties and the experimental induction of diplosporic apomixis are discussed.Key words: Solanum, genetic markers, gene–centromere mapping, desynapsis, reduced recombination.


Author(s):  
Mikel Arrieta ◽  
Glenda Willems ◽  
Jérôme DePessemier ◽  
Isabelle Colas ◽  
Alexandra Burkholz ◽  
...  

Abstract Meiotic recombination plays a crucial role in plant breeding through the creation of new allelic combinations. Therefore, lack of recombination in some genomic regions constitutes a constraint for breeding programmes. In sugar beet, one of the major crops in Europe, recombination occurs mainly in the distal portions of the chromosomes, and so the development of simple approaches to change this pattern is of considerable interest for future breeding and genetics. In the present study, the effect of heat stress on recombination in sugar beet was studied by treating F1 plants at 28 °C/25 °C (day/night) and genotyping the progeny. F1 plants were reciprocally backcrossed allowing the study of male and female meiosis separately. Genotypic data indicated an overall increase in crossover frequency of approximately one extra crossover per meiosis, with an associated increase in pericentromeric recombination under heat treatment. Our data indicate that the changes were mainly induced by alterations in female meiosis only, showing that heterochiasmy in sugar beet is reduced under heat stress. Overall, despite the associated decrease in fertility, these data support the potential use of heat stress to foster recombination in sugar beet breeding programmes.


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