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Female puberty is subject to Polycomb Group (PcG)-dependent transcriptional repression.Kiss1, a puberty-activating gene, is a key target of this silencing mechanism. Using a gain-of-function approach and a systems biology strategy we now show that EED, an essential PcG component, acts in the arcuate nucleus of the hypothalamus to alter the functional organization of a gene network involved in the stimulatory control of puberty. A central node of this network isKdm6b, which encodes an enzyme that erases the PcG-dependent histone modification H3K27me3.Kiss1is a first neighbor in the network; genes encoding glutamatergic receptors and potassium channels are second neighbors. By repressingKdm6bexpression, EED increases H3K27me3 abundance at these gene promoters, reducing gene expression throughout a gene network controlling puberty activation. These results indicate thatKdm6brepression is a basic mechanism used by PcG to modulate the biological output of puberty-activating gene networks.

 

The effect of CO rotational energy on bimolecular reactions to form electronically excited C 2 is reported here. The reactions are initiated by CO multiphoton absorption of 800 nm light in strong optical fields using two different polarization configurations based on shaped chirped pulses. The observation of Swan band emission indicates that C 2 (d 3 Π g ) is a reaction product. The optical polarization is in the form of either an optical centrifuge or a dynamic polarization grating. In each case, the strong field aligns CO molecules and induces multiphoton absorption. Power-dependent measurements indicate at least seven photons are absorbed by CO; CO(a 3 Π) is a likely reactant candidate based on kinetic modeling. Relative reaction efficiencies are determined by measuring Swan band emission intensities. For a CO pressure of 100 Torr and an optical intensity of I = 2.0 × 10 13 W cm −2 , the relative C 2 (d 3 Π g ) yield with the dynamic polarization grating is twice that with the optical centrifuge. The extent of CO rotational energy was determined for both optical polarizations using high-resolution transient IR absorption for a number of CO states with J = 62–73 and E rot up to 10 400 cm −1 . Optical centrifuge excitation generates at least 2.5 times more rotationally excited CO molecules per quantum state than the dynamic polarization grating. The results indicate that the effect of large amounts of CO rotational energy is to reduce the yield of the C 2 products.