Regulation of Human Epidermal Keratinocyte Differentiation by the Vitamin D Receptor and its Coactivators DRIP205, SRC2, and SRC3

It has long been known that the active metabolite of vitamin D, 1,25 dihydroxyvitamin D3, stimulates differentiation and inhibits proliferation in epidermal keratinocytes through interaction with the vitamin D receptor (VDR). VDR functions through the coordinate binding of vitamin D response elements in the DNA and specific coactivator proteins which help to initiate transcription. It was recently observed that VDR binds to two major coactivator complexes, DRIP (VDR-interacting protein) and SRC (steroid receptor coactivator), during keratinocyte differentiation. To determine the role of VDR and its coactivators in mediating keratinocyte differentiation, we developed an adenoviral system to knock down, or in the case of VDR, overexpress these genes. In order to study all stages of keratinocyte development, we employed an advanced differentiated normal human keratinocyte culture system that produces a multilayer phenotype similar to that of normal skin. These studies have shown that VDR, DRIP, and SRC are all required for promotion of both early and late keratinocyte differentiation. Additionally, each individual differentiation marker that was assayed has a different specificity for the coactivators that regulate its expression

Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, whereas the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained

Roles for Class III HD-Zip and KANADI Genes in Arabidopsis Root Development

Meristems within the plant body differ in their structure and the patterns and identities of organs they produce. Despite these differences, it is becoming apparent that shoot and root apical and vascular meristems share significant gene expression patterns. Class III HD-Zip genes are required for the formation of a functional shoot apical meristem. In addition, Class III HD-Zip and KANADI genes function in patterning lateral organs and vascular bundles produced from the shoot apical and vascular meristems, respectively. We utilize both gain- and loss-of-function mutants and gene expression patterns to analyze the function of Class III HD-Zip and KANADI genes in Arabidopsis roots. Here we show that both Class III HD-Zip and KANADI genes play roles in the ontogeny of lateral roots and suggest that Class III HD-Zip gene activity is required for meristematic activity in the pericycle analogous to its requirement in the shoot apical meristem

Allyl Glycidyl Ether-Based Polymer Electrolytes for Room Temperature Lithium Batteries

A new family of polymer electrolytes based on a poly­(allyl glycidyl ether) (PAGE) platform has been developed that overcomes many of the limitations of poly­(ethylene oxide) (PEO) for battery electrolyte applications. PAGE was shown to have peak conductivities at [O]/[Li] = 16, with σ > 3 × 10^–5 S/cm at 25 °C and σ > 5 × 10^–4 S/cm at 80 °C. Below 60 °C, PAGE has a conductivity that is 10–100 times higher than that of PEO at equivalent salt concentrations with this disparity in conductivities between PAGE and PEO increasing with decreasing temperature. In addition, the synthetic versatility of allyl glycidyl ether as a building block is demonstrated by the preparation and evaluation of various AGE–EO macromolecular architectures that show superior performance to both PAGE and PEO

DEFECTIVE EMBRYO AND MERISTEMS genes are required for cell division and gamete viability in Arabidopsis

The DEFECTIVE EMBRYO AND MERISTEMS 1 (DEM1) gene encodes a protein of unknown biochemical function required for meristem formation and seedling development in tomato, but it was unclear whether DEM1's primary role was in cell division or alternatively, in defining the identity of meristematic cells. Genome sequence analysis indicates that flowering plants possess at least two DEM genes. Arabidopsis has two DEM genes, DEM1 and DEM2, which we show are expressed in developing embryos and meristems in a punctate pattern that is typical of genes involved in cell division. Homozygous dem1 dem2 double mutants were not recovered, and plants carrying a single functional DEM1 allele and no functional copies of DEM2, i.e. DEM1/dem1 dem2/dem2 plants, exhibit normal development through to the time of flowering but during male reproductive development, chromosomes fail to align on the metaphase plate at meiosis II and result in abnormal numbers of daughter cells following meiosis. Additionally, these plants show defects in both pollen and embryo sac development, and produce defective male and female gametes. In contrast, dem1/dem1 DEM2/dem2 plants showed normal levels of fertility, indicating that DEM2 plays a more important role than DEM1 in gamete viability. The increased importance of DEM2 in gamete viability correlated with higher mRNA levels of DEM2 compared to DEM1 in most tissues examined and particularly in the vegetative shoot apex, developing siliques, pollen and sperm. We also demonstrate that gamete viability depends not only on the number of functional DEM alleles inherited following meiosis, but also on the number of functional DEM alleles in the parent plant that undergoes meiosis. Furthermore, DEM1 interacts with RAS-RELATED NUCLEAR PROTEIN 1 (RAN1) in yeast two-hybrid and pull-down binding assays, and we show that fluorescent proteins fused to DEM1 and RAN1 co-localize transiently during male meiosis and pollen development. In eukaryotes, RAN is a highly conserved GTPase that plays key roles in cell cycle progression, spindle assembly during cell division, reformation of the nuclear envelope following cell division, and nucleocytoplasmic transport. Our results demonstrate that DEM proteins play an essential role in cell division in plants, most likely through an interaction with RAN1