G1/S transcription factors assemble in increasing numbers of discrete clusters through G1 phase.

In budding yeast, the transcription factors SBF and MBF activate a large program of gene expression in late G1 phase that underlies commitment to cell division, termed Start. SBF/MBF are limiting with respect to target promoters in small G1 phase cells and accumulate as cells grow, raising the questions of how SBF/MBF are dynamically distributed across the G1/S regulon and how this impacts the Start transition. Super-resolution Photo-Activatable Localization Microscopy (PALM) mapping of the static positions of SBF/MBF subunits in fixed cells revealed each transcription factor was organized into discrete clusters containing approximately eight copies regardless of cell size and that the total number of clusters increased as cells grew through G1 phase.

Genetic profile considerations for induction of allogeneic chimerism as a therapeutic approach for type 1 diabetes mellitus.

The major therapeutic modality for type 1 diabetes mellitus (T1DM) remains sustaining euglycemia by exogenous administration of insulin. Based on a new understanding of bone marrow structural and functional dynamics, a conditioning-free bone marrow transplantation (BMT), with reduced adverse effects, opens the possibility for evaluating β cell regeneration and restoration of euglycemia by induction of allogeneic chimerism in patients T1DM, as shown in a mouse model. With this therapeutic modality, donor bone marrow (BM) selection based on T1DM-predisposing and preventive phenotypes will improve treatment outcomes by limiting the risk of exacerbating the autoimmune processes in the BM recipient.

Cell-based immunomodulatory therapy approaches for type 1 diabetes mellitus.

Physiologically sufficient β cell regeneration can be achieved by the induction of hematopoietic chimerism in a type 1 diabetes mellitus (T1DM) mouse model. However, pancytopenia and graft-versus-host disease (GVHD) limits the clinical adaptation of this modality. In this review, we discuss new perceptions on the induction of chimerism, without bone marrow (BM) recipient conditioning, via supplementation of mesenchymal stem cells (MSCs) to support engraftment of allogeneic HSCs.

G1/S Transcription Factor Copy Number Is a Growth-Dependent Determinant of Cell Cycle Commitment in Yeast.

To understand how commitment to cell division in late G1 phase (Start) is controlled by growth and nutrients in budding yeast, we determined the absolute concentrations of the G1/S transcription factors SBF (composed of Swi4 and Swi6) and MBF (composed of Mbp1 and Swi6), the transcriptional repressor Whi5, and the G1 cyclins, Cln1 and Cln2, in single live yeast cells using scanning number and brightness (sN&B) microscopy. In rich medium, Whi5, Mbp1, and Swi6 concentrations were independent of cell size, whereas Swi4 concentration doubled in G1 phase, leading to a size-dependent decrease in the Whi5/Swi4 ratio. In small cells, SBF and MBF copy numbers were insufficient to saturate target G1/S promoters, but this restriction diminished as cells grew in size.

Nanosecond Dynamics of Gαi1 Bound to Nucleotides or Ric-8A, a Gα Chaperone with GEF Activity.

Resistance to Inhibitors of Cholinesterase A (Ric-8A) is a 60-kDa cytosolic protein that has chaperone and guanine nucleotide exchange (GEF) activity toward heterotrimeric G protein α subunits of the i, q, and 12/13 classes, catalyzing the release of GDP from Gα and subsequent binding of GTP. In the absence of GTP or GTP analogs, and subsequent to GDP release, Gα forms a stable nucleotide-free complex with Ric-8A. In this study, time-resolved fluorescence anisotropy measurements were employed to detect local motions of Gαi1 labeled at selected sites with Alexa 488 (C5) fluorescent dye (Ax) in the GDP, GTPγS (collectively, GXP), and Ric-8A-bound states.

Vibrational relaxation of O3(ν2) by O((3)P).

Laboratory measurements of the rate coefficient for quenching of O3(ν2) by ground-state atomic oxygen, kO(ν2), at room temperature are presented. kO(ν2) is currently not well known and is necessary for appropriate nonlocal thermodynamic equilibrium modeling of the upper mesosphere and lower thermosphere. In this work, a 266 nm laser pulse photolyzes a small amount of O3 in a slow-flowing gas mixture of O3, Xe, and Ar.

Photophysical studies of bioconjugated ruthenium metal-ligand complexes incorporated in phospholipid membrane bilayers.

The luminescent, mono-diimine ruthenium complexes [(H)Ru(CO)(PPh3)2(dcbpy)][PF6] (1) (dcbpy = 4,4'-dicarboxy-2,2'-bipyridyl) and [(H)Ru(CO)(dppene)(5-amino-1,10-phen)][PF6] (2) (dppene = bis(diphenylphosphino)ethylene; phen = phenanthroline) were conjugated with 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE) and with cholesterol in the case of complex 2. Using standard conjugation techniques, compound 1 gives the bis-lipid derivative [(H)Ru(CO)(PPh3)2(dcbpy-N-DPPE2)][PF6] (3), while 2 provides the monolipid conjugate [(H)Ru(CO)(dppene)(1,10-phen-5-NHC(S)-N-DPPE)][PF6] (4) and the cholesterol derivative [(H)Ru(CO)(dppene)(1,10-phen-5-NHC(O)Ocholesteryl)][PF6] (5). These compounds were characterized by spectroscopic methods, and their photophysical properties were measured in organic solvents.

One-step Melt Synthesis of Water Soluble, Photoluminescent, Surface-Oxidized Silicon Nanoparticles for Cellular Imaging Applications.

We have developed a versatile, one-step melt synthesis of water-soluble, highly emissive silicon nanoparticles using bi-functional, low-melting solids (such as glutaric acid) as reaction media. Characterization through transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy shows that the one-step melt synthesis produces nanoscale Si cores surrounded by a silicon oxide shell. Analysis of the nanoparticle surface using FT-IR, zeta potential, and gel electrophoresis indicates that the bi-functional ligand used in the one-step synthesis is grafted onto the nanoparticle, which allows for tuning of the particle surface charge, solubility, and functionality.