The Fukushima Daiichi nuclear power plant (DNPP) accident caused massive releases of radioactivity into the environment. The released highly volatile fission products, such as 129mTe, 131I, 134Cs, 136Cs and 137Cs were found to be widely distributed in Fukushima and its adjacent prefectures in eastern Japan. However, the release of non-volatile actinides, in particular, Pu isotopes remains uncertain almost one year after the accident. Here we report the isotopic evidence for the release of Pu into the atmosphere and deposition on the ground in northwest and south of the Fukushima DNPP in the 20–30 km zones. The high activity ratio of 241Pu/239+240Pu (> 100) from the Fukushima DNPP accident highlights the need for long-term 241Pu dose assessment, and the ingrowth of 241Am. The results are important for the estimation of reactor damage and have significant implication in the strategy of decontamination.

Since the Fukushima Daiichi nuclear power plant (FDNPP) accident in 2011, intensive studies of the distribution of released fission products, in particular (134)Cs and (137)Cs, in the environment have been conducted. However, the release sources, that is, the damaged reactors or the spent fuel pools, have not been identified, which resulted in great variation in the estimated amounts of (137)Cs released. Here, we investigated heavily contaminated environmental samples (litter, lichen, and soil) collected from Fukushima forests for the long-lived (135)Cs (half-life of 2 × 10(6) years), which is usually difficult to measure using decay-counting techniques. Using a newly developed triple-quadrupole inductively coupled plasma tandem mass spectrometry method, we analyzed the (135)Cs/(137)Cs isotopic ratio of the FDNPP-released radiocesium in environmental samples. We demonstrated that radiocesium was mainly released from the Unit 2 reactor. Considering the fact that the widely used tracer for the released Fukushima accident-sourced radiocesium in the environment, the (134)Cs/(137)Cs activity ratio, will become unavailable in the near future because of the short half-life of (134)Cs (2.06 years), the (135)Cs/(137)Cs isotopic ratio can be considered as a new tracer for source identification and long-term estimation of the mobility of released radiocesium in the environment.

One of the key questions regarding intracellular diffusion is how the environment affects molecular mobility. Mostly, intracellular diffusion has been described as hindered, and the physical reasons for this behavior are: immobile barriers, molecular crowding, and binding interactions with immobile or mobile molecules. Using results from multi-photon fluorescence correlation spectroscopy, we describe how immobile barriers and crowding agents affect translational mobility. To study the hindrance produced by immobile barriers, we used sol-gels (silica nanostructures) that consist of a continuous solid phase and aqueous phase in which fluorescently tagged molecules diffuse. In the case of molecular crowding, translational mobility was assessed in increasing concentrations of 500 kDa dextran solutions. Diffusion of fluorescent tracers in both sol-gels and dextran solutions shows clear evidence of anomalous subdiffusion. In addition, data from the autocorrelation function were analyzed using the maximum entropy method as adapted to fluorescence correlation spectroscopy data and compared with the standard model that incorporates anomalous diffusion. The maximum entropy method revealed evidence of different diffusion mechanisms that had not been revealed using the anomalous diffusion model. These mechanisms likely correspond to nanostructuring in crowded environments and to the relative dimensions of the crowding agent with respect to the tracer molecule. Analysis with the maximum entropy method also revealed information about the degree of heterogeneity in the environment as reported by the behavior of diffusive molecules.

In this study, we used electron tomography as well as immuno-gold labeling to analyze the morphology and distribution of proteins within PSDs isolated from rats before birth (embryonic day 19) and at post-natal days 2, 21 and 60. Our data provides direct evidence of distinct morphological and compositional differences in PSDs throughout development. Not all PSD components are present at the early stages of development, with a near lack of the scaffolding molecule PSD-95 at E19 and P2. The presence of NR1 and NR2b suggests that PSD-95 is not directly required for clustering of N-methyl-D-aspartic acid (NMDA) receptors in PSDs early in development. α-Actinin is abundant by E19 suggesting it is a core structural component of the PSD. Both α and β isoforms of Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) are present early on, but then rise in labeling density approximately four-fold by P21. Of all the molecules studied, only calmodulin (CaM) was found in higher abundance early in PSD development and then fell in amount over time. Spatial analysis of the immuno-gold label shows a non-random distribution for all the proteins studied, lending support to the idea that the PSD is systematically assembled in an organized fashion. Morphological data from electron tomography shows that the PSD undergoes major structural changes through out development.

binding to the C-domain of CaM. Specifically, PEP-19 accelerates the rates of both association and dissociation of Ca 2ϩ without greatly affecting the overall K Ca of the C-domain (5). RC3 accelerates the rate of Ca 2ϩ dissociation from CaM, but has a lesser effect on the association rate, thereby decreasing the affinity of binding Ca 2ϩ to the C-domain of CaM (6). Importantly, both PEP-19 and RC3 exert these effects even when CaM is bound to CaM-dependent protein kinase II (CKII␣) (5, 6).These results suggest that PEP-19 and RC3 could have broad extrinsic effects on CaM-related signaling pathways by modulating the Ca 2ϩ binding properties of free or enzyme-bound CaM. This is consistent with the phenotype of RC3 knock-out mice, which show defects in synaptic plasticity (7), attenuated phosphorylation of hippocampal protein kinase A and C substrates (8), and altered Ca 2ϩ dynamics in cortical neurons (9). Both PEP-19 and RC3 contain an IQ motif. This rather loose consensus sequence (IQXXXRGXXXR) was first identified as the light chain binding site in conventional myosins, but was subsequently recognized as a CaM binding sequence in numerous other proteins (10). IQ motif proteins exhibit diverse modes of interaction with CaM that include Ca 2ϩ -dependent or independent binding (10), binding to both or only one domain of CaM (5, 11-13), binding multiple CaMs to multiple IQ motifs (14), and exchange of CaM between the IQ motif and other sites in the same protein (15, 16).These intriguing structure-function relationships of IQ motifs led us to identify amino acids in PEP-19 that are required to modulate Ca 2ϩ binding to CaM. We show here that the consensus IQ CaM binding motif is necessary, but not sufficient to mimic the effect of intact PEP-19 on CaM. An adjacent highly acidic amino acid sequence acts in synergy with the IQ motif to modulate Ca 2ϩ binding to the C-domain of CaM. We propose that this acidic/IQ sequence constitutes a new CaM regulatory motif. EXPERIMENTAL PROCEDURESRecombinant Proteins and Peptides-Recombinant CaM, CaM(K75C), CaM(T110C), CaM(T34C), CaM(T34C,T110C), PEP19, and RC3 were cloned, expressed, and purified as described previously (5, 6, 16 -18). The expression plasmid for the C-domain of CaM (residues 78 -148) was a generous gift * This work was supported in part by National Institutes of Health Grants GM069611 and NS038310 and Robert A. Welch Foundation Grant AU1144. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. -bound calmodulin; CaM ACR , acrylodan labeled CaM(K75C); CaM DANS , IAEDANS labeled CaM(K75C); CKII, CaM-dependent protein kinase II; RC3, neurogranin; FRET, fluorescence resonance energy transfer; MOPS, 4-morpholinepropanesulfonic acid; acrylodan, 6-acryloyl-2-dimethylaminonaphthalene; IAEDANS, 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-1-sulfonic acid; DDPM,maleimide; HPLC, high performance liq...

Laparoscopic hepatectomy (LH) has become popular as a surgical treatment for liver diseases, and numerous recent studies indicate that it is safe and has advantages in selected patients. Because of the magnified view offered by the laparoscope under pneumoperitoneal pressure, LH results in less bleeding than open laparotomy. However, gas embolism is an important concern that has been discussed in the literature, and experimental studies have shown that LH is associated with a high incidence of gas embolism. Major hepatectomies are done laparoscopically in some centers, even though the risk of gas embolism is believed to be higher than for minor hepatectomy due to the wide transection plane with dissection of major hepatic veins and long operative time. At many high-volume centers, LH is performed at a pneumoperitoneal pressure less than 12 mmHg, and reports indicate that the rate of clinically severe gas embolism is low. However, more studies will be necessary to elucidate the optimal pneumoperitoneal pressure and the incidence of gas embolism during LH.

Neurogranin (Ng) is a postsynaptic IQ-motif containing protein that accelerates Ca(2+) dissociation from calmodulin (CaM), a key regulator of long-term potentiation and long-term depression in CA1 pyramidal neurons. The exact physiological role of Ng, however, remains controversial. Two genetic knockout studies of Ng showed opposite outcomes in terms of the induction of synaptic plasticity. To understand its function, we test the hypothesis that Ng could regulate the spatial range of action of Ca(2+)/CaM based on its ability to accelerate the dissociation of Ca(2+) from CaM. Using a mathematical model constructed on the known biochemistry of Ng, we calculate the cycle time that CaM molecules alternate between the fully Ca(2+) saturated state and the Ca(2+) unbound state. We then use these results and include diffusion of CaM to illustrate the impact that Ng has on modulating the spatial profile of Ca(2+)-saturated CaM within a model spine compartment. Finally, the first-passage time of CaM to transition from the Ca(2+)-free state to the Ca(2+)-saturated state was calculated with or without Ng present. These analyses suggest that Ng regulates the encounter rate between Ca(2+) saturated CaM and its downstream targets during postsynaptic Ca(2+) transients.

We used a particle-based Monte Carlo simulation to dissect the regulatory mechanism of molecular translocation of CaMKII, a key regulator of neuronal synaptic function. Geometry was based upon measurements from EM reconstructions of dendrites in CA1 hippocampal pyramidal neurons. Three types of simulations were performed to investigate the effects of geometry and other mechanisms that control CaMKII translocation in and out of dendritic spines. First, the diffusional escape rate of CaMKII from model spines of varied morphologies was examined. Second, a postsynaptic density (PSD) was added to study the impact of binding sites on this escape rate. Third, translocation of CaMKII from dendrites and trapping in spines was investigated using a simulated dendrite. Based on diffusion alone, a spine of average dimensions had the ability to retain CaMKII for duration of ~4 s. However, binding sites mimicking those in the PSD controlled the residence time of CaMKII in a highly nonlinear manner. In addition, we observed that F-actin at the spine head/neck junction had a significant impact on CaMKII trapping in dendritic spines. We discuss these results in the context of possible mechanisms that may explain the experimental results that have shown extended accumulation of CaMKII in dendritic spines during synaptic plasticity and LTP induction.