We investigate the two-dimensional (R, Z) distribution of molecules in circumstellar disks around young stellar objects. In the Z-direction, the disk can be schematically divided into three layers: the midplane, the outermost surface region, and the intermediate region. On the midplane, in cool outer regions of a disk, most of the molecules are adsorbed onto grains within a short time and deple...

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate neuronal excitability, pacemaking, dendritic integration, and homeostatic plasticity and are culprits in aberrant neuronal activity in certain epilepsies. In this issue of Neuron two manuscripts (Santoro et al. and Zolles et al.) report that HCN channel gating and expression are controlled by Trip8b (Pex5R) but with a b...

We report the detection of HCO(J=1→0) emission towards the Cloverleaf quasar (z = 2.56) through observations with the Very Large Array. This is the first detection of ionized molecular gas emission at high redshift (z > 2). HCO emission is a star formation indicator similar to HCN, tracing dense molecular hydrogen gas (n(H2) ≃ 10 5 cm) within star–forming molecular clouds. We derive a lensing–c...

Circadian pacemaking in suprachiasmatic nucleus (SCN) neurons revolves around transcriptional/posttranslational feedback loops, driven by protein products of "clock" genes. These loops are synchronized and sustained by intercellular signaling, involving vasoactive intestinal peptide (VIP) via its VPAC2 receptor, which positively regulates cAMP synthesis. In turn, SCN cells communicate circadian...

The different HCN elimination pathways from vinyl cyanide (VCN) are studied in this paper using RRKM, Kinetic Monte Carlo (KMC), and quasi-classical trajectory (QCT) calculations. A new HCN elimination pathway proves to be very competitive with the traditional 3-center and 4-center mechanisms, particularly at low excitation energies. However, low excitation energies have never been experimental...

The HCN emission features near 3 μm recently detected by Geballe et al. (2003, Astrophys. J. 583, L39) are analyzed with a model for fluorescence of sunlight in the ν3 band of HCN. The emission spectrum is consistent with current knowledge of the atmospheric temperature profile and the HCN distribution inferred from millimeter-wave observations. The spectrum is insensitive to the abundance of H...

Purpose Phosphene perception is a characteristic side effect of heart rate-reducing medication that acts on hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels. It is hypothesized that these phosphenes are caused by blocking HCN channels in photoreceptors and neurons of the retina, yet the underlying changes in visual signal processing in the retina caused by the HCN channel ...

Spinal cord injury (SCI) leads to bereft voluntary control of bladder, but the possible role of spontaneous excited system in bladder of SCI patients is poorly understood. Hyper-polarization-activated cyclic nucleotide-gated (HCN) channels are deemed to regulate the spontaneous contraction of bladder, our study explored the functional role of HCN channels in SCI induced neurogenic bladder. Sixt...

Hormone and neurotransmitter release from vesicles is mediated by regulated exocytosis, where an aqueous channel-like structure, termed a fusion pore, is formed. It was recently shown that second messenger cAMP modulates the fusion pore, but the detailed mechanisms remain elusive. In this study, we asked whether the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are a...

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1-4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides a...