1. Chromatin Regulation in the C. elegans Germ Line
MES-4
Chromatin Regulation in the C. elegans Germ Line

2. XO XX Dosage compensation in worms: soma germline both Xs are
reduced ~50%
Females (=hermaphrodites) can self-fertilize
Males arise infrequently; can cross-fertilize
germline
Xs are not
transcribed

3. How chromatin is organized…

4. H4 H3 H4 H3 The Histone Code N N N N N N methylated Lys 20 silencing
acetylated
Lys 8, 12, 16
activating
methylated
Lys 27
silencing
methylated
Lys 9
silencing
methylated
Lys 4, 36
activating

5. H2A H3 H2B H4 The nucleosome. Get better resolution! Ref.
Kornberg and Lorch, Cell 1999

6. MES-4 binds to just 5 of the 6 chromosomes.
maternal
pronucleus
paternal
pronucleus
So I sidetracked to finish up work by Youyi Fong, who showed that the chromatin-binding protein MES-4 was excluded from the X in embryos.
Emphasize how exciting this was!
I never got back to P granules (although I still think they’re cool).
It turns out that MES-4 localization on autosomes corresponds to a specific mark that MES-4 (probably) puts there: it modifies a histone protein - one of the small, basic proteins that form nucleosomes….
MES-4 + DNA
DNA alone

7. H3-Lys36 di-methylation is on Xs in early embryos.
MES-4 is required for H3-Lys36 di-methylation.
1-cell WT
2mK36 WT
mes-4
mes-4

8. Chromatography

9. Sucrose Gradients

10. Gel Electrophoresis

11. Antibody Use in Detection of Target Protein

12. MES-4 and its homologs
NSD1 catalyzes H3 Lys36 and H4 Lys20 methylation in vitro.
(Raysam et al., EMBO J 2003)

13. C. elegans (MES-4) and C. briggsae (CBG60706) Homologs

14. MES-4 and CBG60706

15. CB60706 and MES-4 Introns and Exons

16. Nucleotide Alignment

17. BLAST Amino Acid Alignment Under Default Settings