For example, BrdU that is used to substitute thymidine residues in DNA and required for harlequin staining pattern of sister chromatids
for analysis is known to be genotoxic and can result in slightly increased SCE frequency of around 1-3 per metaphase [28-30].
In the male population aneuploidies appear due to meiotic synapse abnormalities resulting in the creation of bivalent sister chromatids
which lead to abnormal sperm morphology production, or meiotic arrest.
Cre recombinase can mediate two types of recombination between loxP sites on an identical chromosome or between loxP sites on replicated sister chromatids
. Recombination in an identical chromosome leads to inversion of the fragment bracketed by loxP sites.
Scientists from Japan, Europe, and the US discuss the history of mitosis research and the model systems that have played a key role; how threads are produced through chromosome condensation; how sister chromatids
attach to each other and to the spindle apparatus; how the spindle microtubules nucleate, elongate, pause, and shrink; how kinetochores and centrosomes serve as anchor and control points; the biochemical elements that coordinate the main regulatory stages of entry into mitosis, sister chromatid
separation, and mitotic exit; how cells can mis-segregate and unbalance the genome; the cellular changes that occur during cytokinesis; and the differences between mitosis and meiosis.
Seven markers revealed that the fetus inherited with two maternal alleles and one paternal allele, which prove maternal inheritance of triploidy that occurred due to failure of homologous chromosome or sister chromatids
to separate properly in meiosis-I.
mechanism because gametes contain non-sister chromatids
The centromere is the part of a chromosome that links sister chromatids
. At each centromere binds a multi-protein complex named the kinetochore.
The damaged chromosomes, in the form of acentric chromatids
or chromosome fragments, lag behind in anaphase when centric elements move towards the spindle poles.
SCE assay is a short-term test for the detection of reciprocal exchanges of DNA between two sister chromatids
of a duplicating chromosome.The experimental procedure was conducted following the protocol of Allen (1982) using single exposure of test substance.
At day 1 after enucleation, 85 genes have been up-/downregulated, while at day 15 of the process only 7 such genes have been found, among them genes directly involved in cell cycle regulation, for example, cyclins (cyclin E1, E2, and B1), cyclin-dependent kinases (Cdk6 and Cdk1)--enzymes that regulate transcription, mRNA processing and progression of cell cycle, also enzymes involved in separation of sister chromatids
during anaphase, centromere proteins (Cenpe and Cenpf), and kinetochore proteins (Ska3).
For example, small autosomes presenting double breaks on the same chromatid
and others showing gaps in both chromatids
can be appreciated in Figure 2 B and D.
The first division, on the other hand, exhibits three major modifications: (i) meiotic pairing to allow recombination, (ii) kinetochore coorientation to allow for homologous chromosome segregation during anaphase I, and (iii) stepwise loss of cohesion to ensure that sister chromatids
segregate together in meiosis I .
Accurate chromosome segregation requires that chromosomes be bi-oriented, so we begin testing the model by attempting to describe the orientation of the sister chromatids
in mitosis and that of the two synapsed chromosomes in meiosis.
(4) There are a number of distinct mechanisms leading to CI, which include mutations or alterations in genes encoding centromeric proteins and regulators of the cell cycle and mitosis, as well as telomeric loss with fusion of chromatids
and subsequent chromosome fragmentation during mitosis.
Before meiosis, each chromosome is replicated, forming two sisters "chromatids
" that remain linked together.