Short-time photodissociation dynamics of A-band and B-band bromoiodomethane in solution: An examination of bond selective electronic excitation

We have obtained resonance, Raman spectra and absolute Raman cross section measurements at eight excitation wavelengths in the A-band and B-band absorptions of bromoiodomethane in cyclohexane solution. The resonance Raman intensities and absorption spectra were simulated using a simple model and time-dependent wave packet calculations. Normal mode vibrational descriptions were used with.the results of the calculations to find the short-time photodissociation dynamics in terms of internal coordinates. The A-band short-time photodissociation dynamics indicate that the C-I bond becomes much longer, the C-Br bond becomes smaller, the I-C-Br angle becomes smaller, the H-C-Br angles become larger, the H-C-I angles become smaller, and the H-C-H angle becomes a bit smaller. The B-band short-time photodissociation dynamics indicate the C-Br bond becomes much longer, the C-I bond becomes slightly longer, the I-C-Br angle becomes smaller, the H-C-I angles become larger, the H-C-Br angles become smaller, and the H-C-H angle becomes slightly smaller. Both the A-band and B-band short-time photodissociation dynamics appear to be most consistent with an impulsive "semi-rigid" radical model qualitative description of the photodissociation with the CH 2Br radical changing to a more planar structure in the A-band and the CH 2I radical changing to a more planar structure in the B band. We have carried out a Gaussian deconvolution of the A-band and B-band absorption spectra of bromoiodomethane, as well as iodomethane and bromomethane. The absorption spectra, resonance Raman intensities, and short-time photodissociation dynamics sueeest a moderate amount of coupling of the C-I and C-Br chromophores. © 1996 American Institute of Physics.published_or_final_versio

ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer

published_or_final_versio

ERα inhibits epithelial-mesenchymal transition by suppressing Bmi1 in breast cancer

published_or_final_versio

Ca2+ Permeable AMPA Receptor Induced Long-Term Potentiation Requires PI3/MAP Kinases but Not Ca/CaM-Dependent Kinase II

Ca2+ influx via GluR2-lacking Ca2+-permeable AMPA glutamate receptors (CP-AMPARs) can trigger changes in synaptic efficacy in both interneurons and principle neurons, but the underlying mechanisms remain unknown. We took advantage of genetically altered mice with no or reduced GluR2, thus allowing the expression of synaptic CP-AMPARs, to investigate the molecular signaling process during CP-AMPAR-induced synaptic plasticity at CA1 synapses in the hippocampus. Utilizing electrophysiological techniques, we demonstrated that these receptors were capable of inducing numerous forms of long-term potentiation (referred to as CP-AMPAR dependent LTP) through a number of different induction protocols, including high-frequency stimulation (HFS) and theta-burst stimulation (TBS). This included a previously undemonstrated form of protein-synthesis dependent late-LTP (L-LTP) at CA1 synapses that is NMDA-receptor independent. This form of plasticity was completely blocked by the selective CP-AMPAR inhibitor IEM-1460, and found to be dependent on postsynaptic Ca2+ ions through calcium chelator (BAPTA) studies. Surprisingly, Ca/CaM-dependent kinase II (CaMKII), the key protein kinase that is indispensable for NMDA-receptor dependent LTP at CA1 synapses appeared to be not required for the induction of CP-AMPAR dependent LTP due to the lack of effect of two separate pharmacological inhibitors (KN-62 and staurosporine) on this form of potentiation. Both KN-62 and staurosporine strongly inhibited NMDA-receptor dependent LTP in control studies. In contrast, inhibitors for PI3-kinase (LY294002 and wortmannin) or the MAPK cascade (PD98059 and U0126) significantly attenuated this CP-AMPAR-dependent LTP. Similarly, postsynaptic infusion of tetanus toxin (TeTx) light chain, an inhibitor of exocytosis, also had a significant inhibitory effect on this form of LTP. These results suggest that distinct synaptic signaling underlies GluR2-lacking CP-AMPAR-dependent LTP, and reinforces the recent notions that CP-AMPARs are important facilitators of synaptic plasticity in the brain

Investigation of bond-selective electronic excitation in bromoiodomethane

We have obtained resonance Raman spectra with 266 and 218 nm excitation in the A- and B-band absorption spectra of bromoiodomethane in order to investigate the nature of bond selective excitation in this prototypical molecule. Our resonance Raman spectra display overtones and/or combination bands of three Franck-Condon active vibrational modes: ν 4 (the nominal C-Br stretch), ν 5 (the nominal C-I stretch), and ν 6 (the nominal Br-C-I bend). The spectra suggest that upon excitation in the A- and B-band absorptions the bromoiodomethane photodissociation has a degree of multidimensional character and noticeable coupling between the C-I and C-Br chromophores. © 1995 American Chemical Society.link_to_subscribed_fulltex

Isolation and characterization of Oenococcus oeni from Aglianico wines.

A technological characterization of Oenococcus oeni strains isolated from Aglianico wines was performed to select starter cultures for malolactic fermentation (MLF). One hundred and fifty six O. oeni isolates were extracted from Aglianico wines, and identified by using speciesspecific PCR. Malolactic activity (MLA), sulphur dioxide (SO2) resistance, acetaldehyde metabolism and other technological characteristics were tested. Differences in the technologically relevant characteristics were observed. All O. oeni strains were able to grow at low temperature and none in presence of 14% of ethanol. About 80% of O. oeni degraded more than 80% of acetaldehyde, producing ethanol and acetic acid as final products. Among nine O. oeni chosen, four isolates were sensitive to 60 mg of SO2 l-1, while the other five had high resistance. Considering their technological characteristics, five O. oeni strains could be selected starter cultures for MLF in Aglianico