ben holt

NF–Y transcription factors represent a complex of three proteins called NF–YA, NF–YB and NF–YC. Each protein is highly conserved in eukaryotes, and in the plant lineage has undergone numerous rounds of duplication. Individual NF–Y are emerging as important regulators of several essential plant processes, including embryogenesis, drought resistance, maintenance of meristems in nitrogen-fixing nodules and photoperiod-dependent flowering time. Building on the recent finding that NF–YB2 and NF–YB3 have overlapping functionality in Arabidopsis photoperiod-dependent flowering (Kumimoto et al., 2008), we have identified three NF–YC (NF–YC3, NF–YC4, and NF–YC9) that are also required for flowering, and physically interact in vivo with both NF–YB2 and NF–YB3. Furthermore, NF–YC3, NF–YC4 and NF–YC9 can physically interact with full-length CONSTANS (CO), and are genetically required for CO-mediated floral promotion. Collectively, the present data greatly strengthens and extends the argument that CO utilizes NF–Y transcription factor complexes for the activation of FLOWERING LOCUS T (FT) during photoperiod-dependent floral initiation.

Background Monocots, especially the temperate grasses, represent some of the most agriculturally important crops for both current food needs and future biofuel development. Because most of the agriculturally important grass species are difficult to study (e.g., they often have large, repetitive genomes and can be difficult to grow in laboratory settings), developing genetically tractable model systems is essential. Brachypodium distachyon (hereafter Brachypodium) is an emerging model system for the temperate grasses. To fully realize the potential of this model system, publicly accessible discovery tools are essential. High quality cDNA libraries that can be readily adapted for multiple downstream purposes are a needed resource. Additionally, yeast two-hybrid (Y2H) libraries are an important discovery tool for protein-protein interactions and are not currently available for Brachypodium. Results We describe the creation of two high quality, publicly available Gateway™ cDNA entry libraries and their derived Y2H libraries for Brachypodium. The first entry library represents cloned cDNA populations from both short day (SD, 8/16-h light/dark) and long day (LD, 20/4-h light/dark) grown plants, while the second library was generated from hormone treated tissues. Both libraries have extensive genome coverage (~5 × 107 primary clones each) and average clone lengths of ~1.5 Kb. These entry libraries were then used to create two recombination-derived Y2H libraries. Initial proof-of-concept screens demonstrated that a protein with known interaction partners could readily re-isolate those partners, as well as novel interactors. Conclusions Accessible community resources are a hallmark of successful biological model systems. Brachypodium has the potential to be a broadly useful model system for the grasses, but still requires many of these resources. The Gateway™ compatible entry libraries created here will facilitate studies for multiple user-defined purposes and the derived Y2H libraries can be immediately applied to large scale screening and discovery of novel protein-protein interactions. All libraries are freely available for distribution to the research community.

The relative amounts of primary and secondary sulfates in atmospheric aerosols and precipitation can be estimated from measurements of the stable oxygen isotope ratios. The oxygen-18 content of sulfates formed in power plant stack gases before emission into the atmosphere is significantly higher than that of sulfates formed from sulfur dioxide after emission. Results show that 20 to 30 percent of the sulfates in rain and snow at Argonne, Illinois, are of primary origin.

... Ben D. Holt,l Antoinette G. Engelkemeir, and Adolph Venters Chemistry Division, Argonne National Laboratory, Argonne, IL 60439 ... Date m mdl. PPt Date mg/I. 1m Hinsdale 8/14/70 Addison 8/14/70 Wood Dale 8/14/70 Elmhurst 8/14/70 Oak Brook 8/14/70 Joliet 9/8/70 Villa Park ...

... Ben D. Holt,* Paul 1. Cunningham, and Romesh Kumar Chemical Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue ... aerosol sulfates are continental in nature, (2) the l80 content in aerosol sulfates often varies inversely with barometric pressure, and ...

The Arabidopsis RPM1 protein confers resistance to disease caused by Pseudomonas syringae strains delivering either the AvrRpm1 or AvrB type III effector proteins into host cells. We characterized two closely related RPM1-interacting proteins, RIN2 and RIN3. RIN2 and RIN3 encode RING-finger type ubiquitin ligases with six apparent transmembrane domains and an ubiquitin-binding CUE domain. RIN2 and RIN3 are orthologs of the mammalian autocrine motility factor receptor, a cytokine receptor localized in both plasma membrane caveolae and the endoplasmic reticulum. RIN2 is predominantly localized to the plasma membrane, as are RPM1 and RPS2. The C-terminal regions of RIN2 and RIN3, including the CUE domain, interact strongly with an RPM1 N-terminal fragment and weakly with a similar domain from the Arabidopsis RPS2 protein. RIN2 and RIN3 can dimerize through their C-terminal regions. The RING-finger domains of RIN2 and RIN3 encode ubiquitin ligases. Inoculation with P. syringae DC3000(avrRpm1) or P. syringae DC3000(avrRpt2) induces differential decreases of RIN2 mobility in SDS-PAGE and disappearance of the majority of RIN2. A rin2 rin3 double mutant expresses diminished RPM1- and RPS2-dependent hypersensitive response (HR), but no alteration of pathogen growth. Thus, the RIN2/RIN3 RING E3 ligases apparently act on a substrate that regulates RPM1- and RPS2-dependent HR.

Pathogen recognition by the plant immune system is governed by structurally related, polymorphic products of disease resistance (R) genes. RAR1 and/or SGT1b mediate the function of many R proteins. RAR1 controls preactivation R protein accumulation by an unknown mechanism. We demonstrate that Arabidopsis SGT1b has two distinct, genetically separable functions in the plant immune system: SGT1b antagonizes RAR1 to negatively regulate R protein accumulation before infection, and SGT1b has a RAR1-independent function that regulates programmed cell death during infection. The balanced activities of RAR1 and SGT1, in concert with cytosolic HSP90, modulate preactivation R protein accumulation and signaling competence.