6 research outputs found
Environments for Magnetic Field Amplification by Cosmic Rays
We consider a recently discovered class of instabilities, driven by cosmic
ray streaming, in a variety of environments. We show that although these
instabilities have been discussed primarily in the context of supernova driven
interstellar shocks, they can also operate in the intergalactic medium and in
galaxies with weak magnetic fields, where, as a strong source of helical
magnetic fluctuations, they could contribute to the overall evolution of the
magnetic field. Within the Milky Way, these instabilities are strongest in warm
ionized gas, and appear to be weak in hot, low density gas unless the injection
efficiency of cosmic rays is very high.Comment: 9 pages, 8 figures; Accepted to Ap
The VIL gene CRAWLING ELEPHANT controls maturation and differentiation in tomato via polycomb silencing
VERNALIZATION INSENSITIVE 3-LIKE (VIL) proteins are PHD-finger proteins that recruit
the repressor complex Polycomb Repressive Complex 2 (PRC2) to the promoters of target
genes. Most known VIL targets are flowering repressor genes. Here, we show that the
tomato VIL gene CRAWLING ELEPHANT (CREL) promotes differentiation throughout plant
development by facilitating the trimethylation of Histone H3 on lysine 27 (H3K27me3). We
identified the crel mutant in a screen for suppressors of the simple-leaf phenotype of entire
(e), a mutant in the AUX/IAA gene ENTIRE/SlIAA9, involved in compound-leaf development
in tomato. crel mutants have increased leaf complexity, and suppress the ectopic blade
growth of e mutants. In addition, crel mutants are late flowering, and have delayed and aber rant stem, root and flower development. Consistent with a role for CREL in recruiting PRC2,
crel mutants show drastically reduced H3K27me3 enrichment at approximately half of the
14,789 sites enriched in wild-type plants, along with upregulation of many underlying genes.
Interestingly, this reduction in H3K27me3 across the genome in crel is also associated with
gains in H3K27me3 at a smaller number of sites that normally have modest levels of the
mark in wild-type plants, suggesting that PRC2 activity is no longer limiting in the absence of
CREL. Our results uncover a wide role for CREL in plant and organ differentiation in tomato
and suggest that CREL is required for targeting PRC2 activity to, and thus silencing, a spe cific subset of polycomb targets
NSF 19-501 AccelNet Proposal: Community of Open Scholarship Grassroots Networks (COSGN)
The Community of Open Scholarship Grassroots Networks (COSGN), includes 120 grassroots networks, representing virtually every region of the world and every research discipline. These networks communicate and coordinate on topics of common interest. We propose, using an NSF 19-501 Full-Scale implementation grant, to formalize governance and coordination of the networks to maximize impact and establish standard practices for sustainability. In the project period, we will increase the capacity of COSGN to advance the research and community goals of the participating networks individually and collectively, and establish governance, succession planning, shared resources, andcommunication pathways to ensure an active, community-sustained network of networks. By the end of the project period, we will have established a self-sustaining network of networks that leverages disciplinary and regional diversity, actively collaborates across networks for grassroots organizing, and shares resources for maximum impact on culture change for open scholarship