1. Chapter 12 The Cell Nucleus and the Control of Gene Expression Copyright © 2010 by John Wiley & Sons, Inc.

2. The Cell Nucleus

3. The Nuclear Envelope

4. The Movement of Materials through the Nuclear Pore

7. Importing Proteins from Cytoplasm into Nucleus :Gold Particles coated with Nucleoplasmin Protein injected into cytoplasm of Xenopus oocyte

8. Scanning EM of Nuclear Pore Complexes: isolated nuclear envelopes of an amphibian oocytes

14. Freeze Fracture Studies of Nuclear Envelope

16. The Nuclear Lamina

17. Figure 8.4 Model of Lamin Assembly

18. Figure 8.31 Dissolution of the Nuclear Lamina

20. Figure 8.8 Nuclear Localization Signals

21. Fusion of Nuclear Localization Signal (NLS) to a cytoplasmic protein causes the protein to enter the cell nucleus: Immunofluorescence studies on Pyruvate Kinase import in cell culture

22. Phase Contrast Micrographs of untreated and Digitonin permeabilized He La cells

23. Fluorescence Micrographs of digitonin permeabilized He La cells incubated with a fluorescent protein chemically coupled to a synthetic NLS peptide in the presence and absence of a cytosol lysate

24. Mechanism for Nuclear Import of Cargo Proteins

26. Nuclear Export of Cargo proteins

27. Activation of a Gene by a steroid hormone, Glucocortocoid Sterol

28. Polytene Chromosome Preparation

34. Chromosomes

35. Figure 4.19 The Centromere of a Metaphase Chromosome

36. In situ hybridization of a DNA probe containing the sequence TTAGGG, which localizes to the telomeres of human chromosomes

37. Immunofluorescence studies using anti-RAP1 antibody

38. The end replication problem: The Role of Telomerase

39. The ends of Chromosomes

40. Telomerase: Mechanism of Action

41. Knockout Mice lacking gene for Telomerase

42. Yeast Chromosomes Vectorology

43. Assay of a Centromere in Yeast

44. ARSs “ Autonomously Replicating Sequences” Yeast Genomes contain many ~100 base pair sequences (ARSs), that act as Replication Origins. CEN “ Centromeric Sequences” Unique sequences characteristic of the centromere region. EXPERIMENT:  Insertion of an ARS into a circular plasmid allows the plasmid to replicate in yeast cells! However, only about 5-20 % of progeny cells contain the plasmid because mitotic segregation of the plasmids is faulty.  However, plasmids that also carry a CEN sequence, derived from the centromeres of yeast chromosmes, segregate equally or nearly so to both mother and daughter cells during mitosis.

45. Centromeres of S. cerevisiae, S. pombe, and Drosophila melanogaster

46. Artificial Chromosomes Gene Therapy