Mammals balance X-linked gene dosage by silencing one X chromosome in female cells, a process that begins with counting the number of X chromosomes. Recent reports suggest homologous X chromosome pairing may be a prerequisite for silencing, providing a basis for counting by ensuring that silencing only occurs in cells with two X chromosomes.

aegilops triuncialis l. (2n=4x=28; ctctutut) is one of the tetraploid aegilops species harboring valuable genes for resistance to many biotic and abiotic stresses. in the present study the bread wheat cultivars mv17, navid, omid, pishgam, zarin were crossed with an accession of ae. triuncialis and the resulted f1 and f2 (obtained by the selfing of f1 plants) hybrids studied using the convention...

4-97 ABSTRACT Ploidy in various generic Lolium Festuca progenies were assessed by flow cytometry and compared to conventional chromosome counting. In non-segregating triploid and tetraploid progenies, the cytometer estimated so accurately the level of plant ploidy that chromosomes counting would be no use. In segregant progenies, all the tetraploid plants according to the cytometer had effectiv...

X chromosome inactivation (XCI) is the phenomenon occurring in female mammals whereby dosage compensation of X-linked genes is obtained by transcriptional silencing of one of their two X chromosomes, randomly chosen during early embryo development. The earliest steps of random X-inactivation, involving counting of the X chromosomes and choice of the active and inactive X, are still not understo...

chromosome counting was performed in nine populations of achillea tenuifolia lam and eight populations of a. bieberestinii afan (asteraceae) collected from hamedan and kermanshah provinces in the west of iran. chromosome numbers in both species varied from 2n=2x=18 to 2n=4x=36. some populations of both species showed (2n=4x=36) chromosome number that is the first report as polyploidy levels. an...

The meiotic chromosomes of 3 bulls carrying the 1/29 Robertsonian translocation have been studied. The abnormal chromosome was found in the spermatogonial mitotic divisions of the 3 animals studied. At the diacinesis stage, the trivalent presented several types of association. Chromosome counting of metaphases II showed the presence of 30.2 p. 100 of unbalanced karyotype cells due to excess or ...

Cytology requires chromosome specimens, thus, effective preparation methods are needed. Chromosome specimens frequently prepared from plant root tips. Furthermore, cell cycle synchronization using chemical reagents is applied to obtain a large number of metaphase specimens. In this study, we focused on the timing tip sampling, which optimal for dioecious Silene latifolia. The was determined tim...