1 / 21

Summer 2007 Workshop in Biology and Multimedia for High School Teachers

Summer 2007 Workshop in Biology and Multimedia for High School Teachers. Barr Body: X Chromosome Inactivation. By: E.A. Struzziero. http://faculty.uca.edu/~johnc/Barr%20Body%20Cat.jpg. Murray L. Barr and E. G. Bertram  1949  Dark, drumstick-shaped masses in nuclei of nerve cells

farsiris-hormuzd
Télécharger la présentation

Summer 2007 Workshop in Biology and Multimedia for High School Teachers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Summer 2007 Workshop • in Biology and Multimedia • for High School Teachers

  2. Barr Body:X Chromosome Inactivation By: E.A. Struzziero

  3. http://faculty.uca.edu/~johnc/Barr%20Body%20Cat.jpg.

  4. Murray L. Barr and E. G. Bertram 1949 Dark, drumstick-shaped masses in nuclei of nerve cells Pattern only seen in cats History

  5. History • Mary Lyon 1961 The Lyon Hypothesis (Lyonization) definition: condensation of X chromosome mechanism for inactivating the genes on the chromosome Named inactive X chromosome a Barr body www.biologyreference.com/Re-Se/Sex-Chromosome.html

  6. http://biology.clc.uc.edu/graphics/bio105/barr.jpg

  7. Process • Random selection of X chromosome Inactive throughout cell’s lifetime Xa = active X chromosome Xi = inactive X chromosome

  8. cen Process • X inactivation center (XIC) Near centromere Contains 12 genes • 7 genes code for proteins • 5 genes code for untranslated RNA (Rougeulle et al., 2003) XIC

  9. Process • Xist and Tsix Two genes actively involved in inactivating an X chromosome Antagonistic roles • Xi  Xist expression  Tsix expression • Xa  Xist expression  Tsix expression (Lee et al., 1999)

  10. cen Xist/Tsix in XIC Process • Xist and Tsix Only genes expressed on Xi X chromosome lacking Xist gene cannot be inactivated

  11. Xa Xi cen cen Xist RNA Process • Xist gene (pronounced “exist”) Encodes a large RNA molecule • Coats Xi from the XIC near the centromere outward along the X chromosome (Lyon, 2003)

  12. Process • Mechanism for compacting Xi (Barr body) Enzymes cause the following to occur: • High levels of DNA methylation (CH3) (Chadwick et al., 2003) • Low levels of histone substitution of the acetyl group (CH3CO) for a H atom in a -OH group (www.en.wikipedia.org/wiki/Acetylation)

  13. Xa Xi cen cen CH3 CH3 CH3 CH3 CH3 Xist RNA CH3 CH3 CH3 CH3 CH3

  14. Xa cen cen Xi Process High levels of histone H2A everywhere (deNapoles et al., 2004) High levels of histone H3 methylation (Heard et al., 2001) H2A H3

  15. Barrbody: Source, BIODIDAC, University of Ottawa. http://biodidac.bio.uottawa.ca

  16. REFERENCES • Barrbody: Source, BIODIDAC, University of Ottawa. • http://biodidac.bio.uottawa.ca • Accessed on 7/12/07 • Brown,C.J., Robinson,W.P., (1997), XIST Expression and X-Chromosome Inactivation in Human Preimplantation Embryos. Am. J. Hum. Genet. 61, 5-8 (Full Text PDF • Carrel L, Willard H (2005). "X-inactivation profile reveals extensive variability in X-linked gene expression in females". Nature434 (7031): 400-4. PMID 15772666.  • Chadwick,B.P., Willard,H.F., (2003), Barring gene expression after XIST: maintaining faculative heterochromatin on the inactive X. j.semcdb 14, 359-367 (Abstract)

  17. REFERENCES • de Napoles,M., Mermoud,J.E., Wakao,R., Tang,Y.A., Endoh,M., Appanah,R., Nesterova,T.B., Silva,J., Otte,A.P., Vidal,M., Koseki,H., Brockdorff,N., (2004), Polycomb Group Proteins Ring1A/B Link Ubiquitylation of Histone H2A to Heritable Gene Silencing and X Inactivation. Dev. Cell 7, 663-676 (Abstract) • Hall,L.L., Lawrence,J.B., (2003), The Cell Biology of a Novel Chromosomal RNA: Chromosome Painting By XIST/Xist RNA Initiates a remodeling cascade. j.semcdb 14, 369-378 (Abstract) • Heard, E., Rougeulle, C., Arnaud, D., Avner, P., Allis, C. D. (2001), Methylation of Histone H3 at Lys-9 Is an Early Mark on the X Chromosome during X Inactivation. Cell 107, 727-738. (Full Text)

  18. REFERENCES • Lee, J. T., Davidow, L. S., Warshawsky, D., (1999), Tisx, a gene antisense to Xist at the X-inactivation centre. Nat. Genet. 21, 400-404. (Full Text) • Lee, J. T., (2003), X-chromosome inactivation: a multi-disciplinary approach. j.semcdb 14, 311-312. (doi:10.1016/j.semcdb.2003.09.025 (Abstract) • Lyon, M. (1961). "Gene action in the X-chromosome of the mouse (Mus musculus L.)". Nature 190: 372-3. PMID 13764598 • Lyon, M. F., (2003), The Lyon and the LINE hypothesis. j.semcdb 14, 313-318. (Abstract)

  19. REFERENCES • Rougeulle, C., Avner, P. (2003), Controlling X-inactivationin mammals: what does the centre hold?. j.semcdb 14, 331-340. (Abstract) • Whitelaw, Emma, “Unravelling the X in Sex”. Developmental Cell 11, 759-762, December 2006. (Full Text) Special thanks to Christine Rodriguez of HHMI-Outreach Program At Harvard University’s Department of Molecular & Cellular Biology with the graphics.

  20. REFERENCES • http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20101/Bio%20101%20Lectures/Genetics-%20Chromosomes/non-mend.htm Accessed on 7/13/07 • http://biology.clc.uc.edu/graphics/bio105/barr.jpg Accessed on 7/12/07(free image) • http://faculty.uca.edu/~johnc/Barr%20Body%20Cat.jpg. Accessed on 7/12/07 • www.whonamedit.com/doctor.cfm/2473.html. Accessed 7/13/07 • www.biologyreference.com/Re-Se/Sex-Chromosome.html) Accessed 7/13/07 • www.en.wikipedia.org/wiki/Acetylation Accessed 7/12/07

More Related