Auditory fear memory is thought to be maintained by fear conditioning-induced potentiation of synaptic efficacy, which involves enhanced expression of surface AMPA receptor (AMPAR) at excitatory synapses in the lateral amygdala (LA). Depotentiation, reversal of conditioning-induced potentiation, has been proposed as a cellular mechanism for fear extinction; however, a direct link between depotentiation and extinction has not yet been tested. To address this issue, we applied both ex vivo and in vivo approaches to rats in which fear memory had been consolidated. A unique form of depotentiation reversed conditioning-induced potentiation at thalamic input synapses onto the LA (T-LA synapses) ex vivo. Extinction returned the enhanced T-LA synaptic efficacy observed in conditioned rats to baseline and occluded the depotentiation. Consistently, extinction reversed conditioning-induced enhancement of surface expression of AMPAR subunits in LA synaptosomal preparations. A GluR2-derived peptide that blocks regulated AMPAR endocytosis inhibited depotentiation, and microinjection of a cell-permeable form of the peptide into the LA attenuated extinction. Our results are consistent with the use of depotentiation to weaken potentiated synaptic inputs onto the LA during extinction and provide strong evidence that AMPAR removal at excitatory synapses in the LA underlies extinction.lateral amygdala ͉ fear conditioning ͉ AMPA receptor ͉ endocytosis T he cortical and thalamic input synapses onto the lateral amygdala (LA) (C-LA and T-LA synapses, respectively) carry auditory information from the auditory cortex and auditory thalamus onto the LA, respectively (1). Long-term potentiation (LTP; an in vitro model of memory) (2)-like changes in these pathways are thought to underlie both the encoding and consolidation of auditory fear memory (3-8). The results of a recent study suggest that long-term retention of conditioning-induced potentiation at excitatory synapses in the LA is a critical requirement for consolidated fear memory within the LA (7, 9). Also, LTP requiring the synaptic delivery of AMPA receptors (AMPARs) at excitatory synapses in the LA appears to be necessary for establishing consolidated fear memory (6,8,10). Conditioning-induced potentiation and auditory fear memory encoded in the LA have been shown to be consolidated within 24 h after fear conditioning (5, 7, 11). Moreover, auditory fear memory appears to be maintained in the LA across the adult lifetime of rats (12). Thus, consolidation of auditory fear memory encoded in the LA is rapid and localized, unlike hippocampus-dependent memory, which involves slow and distributed consolidation processes (13).In the present study, we tested the hypothesis that depotentiation of conditioning-induced potentiation at excitatory synapses in the LA underlies extinction of consolidated fear memory. Synaptic weights were monitored ex vivo by using whole-cell (or field potential) recordings in amygdala slices prepared from behaviortrained rats. Results Extinction of Consolidated ...

We have investigated the radioprotective efficacy of eckol, a component of brown seaweed Ecklonia cava, against the gamma ray-induced damage in vivo. Our results showed that eckol significantly decreased the mortality of lethally irradiated mice. The mechanisms of eckolÕs protection were found to include: an improvement in hematopoietic recovery, the repair of damaged DNA in immune cells and an enhancement of their proliferation, which had been severely suppressed by ionizing radiation. Thus, we propose eckol as a candidate for adjuvant therapy to alleviate radiation-induced injuries to cancer patients.

We investigated whether the brown seaweed Alariaceae Ecklonia cava (E. cava) has immunological effects on splenocytes in vitro. For that purpose, we prepared an enzymatic extract from E. cava (ECK) by using the protease, Kojizyme. Here, ECK administered to ICR mice dramatically enhanced the proliferation of their splenocytes and increased the number of their lymphocytes, monocytes and granulocytes. In flow cytometry assays performed to identify in detail the specific phenotypes of these proliferating cells after ECK treatment, the numbers of CD4(+) T cells, CD8(+) T cells and CD45R/B220(+) B cells increased significantly compared to those in untreated controls. In addition, the mRNA expression and production level of Th1-type cytokines, i.e., TNF-alpha and IFN-gamma, were down-regulated, whereas those of Th2-type cytokines, i.e., IL-4 and IL-10, were up-regulated by ECK. Overall, this dramatic increase in numbers of splenocytes indicated that ECK could induce these cells to proliferate and could regulate the production of Th1- as well as Th2-type cytokines in immune cells. These results suggest that ECK has the immunomodulatory ability to activate the anti-inflammatory response and/or suppress the proinflammatory response, thereby endorsing its usefulness as therapy for diseases of the immune system.

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Alishewanella jeotgali sp. nov., isolated from traditional fermented food, and emended description of the genus Alishewanella The genus Alishewanella is one of the major branches of the family Alteromonadaceae and was first proposed by Fonnesbech Vogel et al. (2000) to accommodate Alishewanella fetalis, isolated from an autopsy of a human fetus in 1992. Recently, another species, Alishewanella aestuarii, from a marine environment, has been reported (Roh et al., 2009). Here, we describe a third novel species that belongs to the genus Alishewanella, isolated from a traditional fermented food in Korea. Strain MS1T was isolated from gajami sikhae (jeotgal), which is a traditional fermented food in Korea. A sample of gajami sikhae was diluted 10 26 -fold with PBS and cultured on R2A agar (Difco). The 16S rRNA gene sequence was amplified by the colony PCR method with PCR Pre-Mix (Intron Biotechnology) and two universal primers for bacteria (Baker et al., 2003). The PCR products were sequenced with a BigDye Terminator Cycle Sequencing Ready Reaction kit (Applied Biosystems) after purification according to the manufacturer's instructions. The reaction mixtures were analysed with an automated system (ABI Prism 3730XL DNA Analyzer; Applied Biosystems) and the 16S rRNA gene sequences were assembled with SEQMAN (DNASTAR). Comparison of the 16S rRNA gene sequence of strain MS1T with those deposited in GenBank revealed that strain MS1T belongs to the genus Alishewanella in the phylum Proteobacteria and that its 16S rRNA gene sequence shares 98.67 and 98.04 % similarity with the sequences of A. aestuarii B11 T and A. fetalis CCUG 30811 T , respectively. The 16S rRNA gene sequence of the isolate was aligned with those of reference strains by using the multiple-sequence alignment program CLUSTAL X (1.83) (Thompson et al., 1997). The phylogenetic relationships between strain MS1T and the representative type strains of Alishewanella species were defined by MEGA4 (Tamura et al., 2007). In the randomly generated neighbour-joining, maximum-parsimony and maximumlikelihood consensus trees constructed from 1000, 1000 and 300 bootstrap replicates, respectively (Felsenstein, 1981;Kluge & Farris, 1969;Saitou & Nei, 1987), strain MS1T formed a monophyletic clade that was separate Abbreviation: TMAO, trimethylamine oxide.The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain MS1 T is EU817498.