Cryogenic Rearrangements of Spiroheptadiyl: Light- or Heavy-Atom Quantum Tunneling?

Triplet 1,4-spiro[2.4]heptadiyl () has been shown experimentally to undergo rapid ring-opening and subsequent 1,2-hydrogen shift upon generation via photolysis of a diazene precursor at cryogenic temperatures. Modern computational tools elucidate the potential energy surface and kinetics behind this cascade reaction, disproving the earlier hypothesized mechanism invoking hot molecule effects in the first ring-opening step and tunneling in the second hydrogen transfer step.

Senescing cells share common features with dedifferentiating cells.

Dedifferentiation signifies the capacity of somatic cells to acquire stem cell-like properties. This process can be induced during normal development and as a response to various stimuli, such as pathogen infection and wounding. Dedifferentiation also characterizes the transition of differentiated leaf cells into protoplasts (plant cells devoid of cell walls), a transition accompanied by widespread chromatin decondensation.

Anxiety characteristics independently and prospectively predict myocardial infarction in men the unique contribution of anxiety among psychologic factors.

Objectives: This study investigated whether anxiety characteristics independently predicted the onset of myocardial infarction (MI) over an average of 12.4 years and whether this relationship was independent of other psychologic variables and risk factors.

Background: Although several psychosocial factors have been associated with risk for MI, anxiety has not been examined extensively.

Histone methylation controls telomerase-independent telomere lengthening in cells undergoing dedifferentiation.

Cellular dedifferentiation underlies topical issues in biology such as regeneration and nuclear cloning and has common features in plants and animals. In plants, this process characterizes the transition of differentiated leaf cells to protoplasts (plant cells devoid of cell walls) and is accompanied by global chromatin reorganization associated with reprogramming of gene expression. A screen for mutants defective in proliferation and callus formation identified kyp-2-a mutant in the KRYPTONITE (KYP)/SUVH4 gene encoding a histone H3 lysine 9 (H3K9) methyltransferase.

Different domains control the localization and mobility of LIKE HETEROCHROMATIN PROTEIN1 in Arabidopsis nuclei.

Plants possess a single gene for the structurally related HETEROCHROMATIN PROTEIN1 (HP1), termed LIKE-HP1 (LHP1). We investigated the subnuclear localization, binding properties, and dynamics of LHP1 proteins in Arabidopsis thaliana cells. Transient expression assays showed that tomato (Solanum lycopersicum) LHP1 fused to green fluorescent protein (GFP; Sl LHP1-GFP) and Arabidopsis LHP1 (At LHP1-GFP) localized to heterochromatic chromocenters and showed punctuated distribution within the nucleus; tomato but not Arabidopsis LHP1 was also localized within the nucleolus.