Segregation, of chromosome

Reik Can you comment on the spatial segregation of chromosomes during the first mitosis that you mention The Mayer et al (2000) study shows this very clearly. We have also carried out the same kind of immunofluorescence studies and we don t see that. This may need some reassessment with other markers. The methyl C antibody may not be the best thing to use. 

The M-hexane metabolite 2,5-hexanedione was strongly positive in an in vitro test for induction of chromosome loss in S. cerevisiae (Mayer and Goin 1994). It was suggested that this effect was due to an effect of 2,5-hexanedione on microtubule function in the yeast cells, resulting in faulty segregation of chromosomes. 

Hybrid cultures as well as other permanent lines of cells maintain the deep freezing (-196 C) and are saved this way. One of the problems of hybrid cultures maintenance and cultivation, especially interspecific, is the segregation of chromosomes. Therefore, the control of desirable correlation saving between hybridization partners chromosomes is obligatory. 

Each parent contributes one allele through random segregation of chromosomes during meiosis. 

One of the major features in the sequence of cell division is the formation of the mitotic spindle and the subsequent separation of chromosomes into their respective daughter cells. An important element of the spindle is the highly conserved, helical molecule tubulin. In addition to spindle formation and the segregation of chromosomes in cell division, alternating helices of a- and -tubulin form the microtubules that form part of the cytoskeleton and have active roles in cell organelle organisation. 

Homologous recombination thus serves at least three identifiable functions (1) it contributes to the repair of several types of DNA damage (2) it provides, in eukaryotic cells, a transient physical link between chromatids that promotes the orderly segregation of chromosomes at the first meiotic cell division and (3) it enhances genetic diversity in a population. 

Pyrazole derivatives, (IV), prepared by Bebbington (4) were effective as Aurora-2 protein kinase inhibitors and impeded the accurate segregation of chromosomes during mitosis and used in treating colon and breast cancers in humans. 

Benet, J Oliver-Bonet, M., Cifuentes, R, Templado, C and Navarro, J., Segregation of chromosomes in sperm of reciprocal translocation carriers a review, Cytogenet. Genome Res. Ill, 281-290, 2005 Apian, P.D., Causes of oncogenic chromosomal translocation. Trends in Genetics 22,46-55, 2006. 

Figure 17.6 Attachment of kinetochores to the spindle. During prometaphase, kinetochores on chromosomes capture microtubules emanating from the spindle poles. Several types of attachments are possible, however only amphitelic (i.e., bipolar) attachment is compatible with segregation of chromosomes to opposite poles when anaphase begins. Monotelic and syntelic attachments trigger the spindle assembly checkpoint to give more time for them to be converted to amphitelic attachments. Merotelic attachments do not trigger the spindle assembly checkpoint but are corrected by a mechanism that requires Aurora B kinase.

Comparison of dithiocarbamates ziram, thiram, zineb and ETU selected on the basis of their loiown or suspected spindle activity (Table 10.5) showed different response in the 4 assays used. The study demonstrated that the selected dithiocarbamates assayed were able to induce aneuploidy in at least one assay. These results support the hypothesis that some carcinogens are capable of disturbing the segregation of chromosomes through their interaction with non-DNA targets. 

Fibers were observed in mitotic cells, interacting with chromosomes, causing mis-segregation of chromosomes, resulting in aneuploidy. Such an effect could induce cell transformation and cancer. 

Centromeres are DNA regions necessary for precise segregation of chromosomes to daughter cells during cell division. A small repeating sequence (GGAAT)n has been found to be conserved across a wide range of species. 

Rockmill, B., and Roeder, G. S. (1988). REDl A yeast gene required for the segregation of chromosomes during the reductional division of meiosis. Proc. Natl. Acad. Sci. U.S.A. 85, 6057-6061. 

There are a number of structural differences between the prokaryotic and eukaryotic types of chromosomes (Ris and Chandler, 1963). For example, chromosomes of viruses, bacteria, and blue-green algae consist of a single DNA molecule which lacks associated histones. In all these prokaryotes the DNA is not separted from the cytoplasm by an enclosing envelope, and segregation of chromosomes at cell division does not occur by a mitotic type of arrangement. Prokaryote chromosomes usually occur singly in cells. All... 

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