Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 24 February 2006:
Vol. 311. no. 5764, pp. 1146 - 1149
DOI: 10.1126/science.1120519
Prev | Table of Contents | Next

Reports

Cell Type Regulates Selective Segregation of Mouse Chromosome 7 DNA Strands in Mitosis

Athanasios Armakolas and Amar J. S. Klar*

Gene Regulation and Chromosome Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702–1201, USA.


Figure 1 Fig. 1. Diagrams of Chr 7 strand segregation patterns following mitotic site-specific recombination [modified from (2)]. The numbers indicate "older" strands and resulting chromatids derived from maternal (no. 1) and paternal (no. 2) parental chromosomes, respectively. Only the specifically designated Wor C parental chromosomes strands are indicated in daughter cells to simplify their representation. The WC:WC pattern in the progenitor cell is indicated when HATr M/P recombinant is obtained (fig. S1), and the WW:CC pattern is reflected by the HATr M/M recombinant. Note that only WC' and W'C chromatids must have recombined in G2 phase in the examples diagrammed here. Alternatively, should recombination be restricted to both WC' or both W'C chromatids, the M/P HATr recombinants will result from the WW:CC pattern and M/M HATr ones from the WC:WC pattern (not diagrammed). To help follow strand distribution, the parental W is colored green, parental C in red, and the newest strands are represented by brown (C') and blue (W') colors. The crossover is indicated as X; P is paternal Snrpn epiallele, M, maternal epiallele; and ellipses represent centromeres. [View Larger Version of this Image (16K GIF file)]
 

Figure 2 Fig. 2. Detection of cell differentiation protein expression markers by immunofluorescence microscopy. (A) FOXA2 and (B) SOX17 of endoderm cells; (C) glucagon and (D) nestin of insulin-secreting pancreatic cells; (E) desmin and (F) smooth muscle actin of cardiomyocytes; (G) Tuj-1 and (H) nestin of neuroectoderm cells; (I) FEC6 of early mesodermal cells. [View Larger Version of this Image (78K GIF file)]
 

Figure 3 Fig. 3. Southern analysis of Chr 7 HATr recombinants selected from indicated cell type cultures. Southern analysis autoradiographs of Sac II plus Taq I double-digests of DNA are shown. The larger (5.3-kb) Taq I–Taq I DNA fragment indicates the maternal (M) Snrpn epiallele; the smaller (1.9-kb) Taq I–Sac II fragment reflects the paternal (P) form (1). The 850-bp Taq I–Sac II fragment was used as the radiolabeled probe. Each lane represents DNA derived from cultures grown from an individual colony. The mouse ES cells panel: Lane 1 contains DNA isolated from a culture infected with the virus containing the SV40 large T antigen; it shows the M/P constitution. Lane 2 contains another control, cells without viral infection and after mitotic recombination showing M/M homozygosis, as demonstrated previously (1). Lanes 3 to 20 represent cultures from independent recombinant colonies of the line that had been infected with the T-antigen gene; all the recombinants tested had become M/M. Results of other indicated cell types and the deduced segregation patterns are presented in other panels. The first control (C) lane in each panel represents P/M constitution of cells of each type. As another M/M control, the second lane (es) contained DNA of the virally infected ES cultures following recombination. Among nearly 100 recombinants of each cell type tested (table S1), DNA analysis of only about 20 recombinants from each cell type is displayed here. [View Larger Version of this Image (62K GIF file)]
 

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)