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Synaptic Protein Degradation as a Mechanism in Memory Reorganization
Kaang, Bong-Kiun,Lee, Sue-Hyun,Kim, Hyoung SAGE Publications 2009 The neuroscientist Vol.15 No.5
<P>An accumulating body of evidence shows that reactivated long-term memory undergoes a dynamic process called reconsolidation, in which de novo protein synthesis is required to maintain the memory. These findings open up a new dimension in the field of memory research. However, few studies have shown how once-consolidated memory becomes labile. The authors’ recent findings have demonstrated that pre-existing long-term memory becomes unstable via the ubiquitin/ proteasome-dependent protein degradation pathway and that this labile state is required for the reorganization of fear memory. Here, the authors review this finding and focus on the labile state that is critical for the reorganization of memory triggered after memory retrieval.</P>
Kaang, Byung Kwon,Han, Nara,Lee, Ha-Jin,Choi, Won San American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.1
<P>Three types of surface treatments, namely, polyethyleneimine (PEI) coating, short PEI (S-PEI) grafting, and long PEI (L-PEI) grafting, were performed on polydopamine (Pdop)-based catalysts to enhance their catalytic activity and stability. Brush-grafted catalysts were prepared by the stepwise synthesis of Au and short (or long) PEI brushes on Pdop particles (PdopP/Au/S- or L-PEI grafting). PEI-coated Pdop-based catalysts (PdopP/Au/PEI coating) were also prepared as non-brush-grafted catalysts. Among the surface-treated PdopP/Au catalysts, the brush-grafted catalysts (S-PEI and L-PEI grafting) exhibited excellent and stable catalytic performance because the brush grafting enabled the protection of the catalysts against harsh conditions, effective transfer of reactants to the catalysts, and confinement of reactants around the catalysts. The brush-grafted catalysts could also more effectively decompose larger dyes than the non-brush-grafted catalysts. The process-to-effectiveness of PEI coating is the best because the release of Pdop from PdopP/Au was moderately inhibited by the presence of only one layer of PEI coating on the PdopP/Au. Thus, this approach could be an alternative method to enhance the stability of PdopP/Au catalysts.</P> [FIG OMISSION]</BR>
Nonlinear evolution of the relativistic Weibel instability driven by anisotropic temperature
Kaang, Helen H.,Mo, Chang 한국우주과학회 2009 한국우주과학회보 Vol.18 No.2
The relativistic Weibel instability has drawn attention as a main mechanism of the magnetic generation in the core of galaxies or in the formation of universe. The Weibel instability is not yet fully understood in the relativistic region. We investigated
Protein Degradation during Reconsolidation as a Mechanism for Memory Reorganization
Kaang, Bong-Kiun,Choi, Jun-Hyeok Frontiers Research Foundation 2011 Frontiers in Behavioral Neuroscience Vol.5 No.-
<P>Memory is a reference formed from a past experience that is used to respond to present situations. However, the world is dynamic and situations change, so it is important to update the memory with new information each time it is reactivated in order to adjust the response in the future. Recent researches indicate that memory may undergo a dynamic process that could work as an updating mechanism. This process which is called reconsolidation involves destabilization of the memory after it is reactivated, followed by restabilization. Recently, it has been demonstrated that the initial destabilization process of reconsolidation requires protein degradation. Using protein degradation inhibition as a method to block reconsolidation, recent researches suggest that reconsolidation, especially the protein degradation-dependent destabilization process is necessary for memory reorganization.</P>
Kaang, Helen H,Ryu, Chang-Mo,Rha, Kicheol,Rhee, Tongnyeol Published jointly by The Institute of Physics and 2012 Plasma physics and controlled fusion Vol.54 No.5
<P>Parametric instabilities of Alfvén-ion-cyclotron (AIC) waves and the turbulence driven by them are investigated using a particle-in-cell simulation technique. By introducing anisotropic ion temperature, a broad spectrum of AIC wave is excited. In addition to the normal AIC waves, their harmonic modes and upper sideband modes are found. Through the interaction of these Alfvénic waves and longitudinal electrostatic waves, Alfvénic turbulence is developed. Excitation of density and electromagnetic waves and their mode coupling structures are investigated using the ω–k spectrum and bicoherence analysis. It is found that the ion-acoustic wave is excited by the modulational instability, and that the ion density mode with a negative group velocity is excited in the high-k region by the decay instability. In addition, a longitudinal mode whose phase velocity behaves similarly to that of the ion-acoustic mode with a shifted wave number is found. This mode is identified as the second harmonic ion-acoustic wave. The inverse cascade structures of the electromagnetic and density fluctuations exhibit an interesting behavior that the density fluctuation shows a dual spectrum, whereas the electrostatic field E<SUB>x</SUB> shows a single spectrum.</P>
Memory and transcription regulation
Kaang, Bong-Kiun 이화여자대학교 세포신호전달연구센터 2008 고사리 세포신호전달 심포지움 Vol. No.10
It is well known that gene regulation by different combinations of transcriptional factors may be involved in specific forms of long-term memory. Multiple pulses of 5-hydroxytryptamine produce long-term facilitation(LTF) in the sensory-to-motor neuron synapses that underlies long-term memory in marine snail Aplysia. LTF depends on transcription and translation. Recently we found novel transcription factors CAMAP and ApLLP, both of which act upstream of ApC/EBP. CAMAP is an associated protein with the cell adhesion molecule apCAM. CAMAP seems to playa dual role in inducing LTF. First it regulates apCAM down-regulation which is required for synaptic outgrowth. Once activated by PKA, it translocates from the plasma membrane into the nucleus and induces ApC/EBP. ApLLP is a small nucleolar protein and induces ApC/EBP by neuronal activity. During the consolidation of long-term memory, a cascade of gene activation is tightly regulated by various transcription factors including positive and negative regulators. It will be highlighted that the molecular mechanisms of synaptic plasticity are strikingly conserved from the invertebrate to the vertebrate system.