Mitochondrial LETM1 drives ionic and molecular clock rhythms in circadian pacemaker neurons.

The mechanisms that generate robust ionic oscillation in circadian pacemaker neurons are under investigation. Here, we demonstrate critical functions of the mitochondrial cation antiporter leucine zipper-EF-hand-containing transmembrane protein 1 (LETM1), which exchanges K+/H+ in Drosophila and Ca2+/H+ in mammals, in circadian pacemaker neurons. Letm1 knockdown in Drosophila pacemaker neurons reduced circadian cytosolic H+ rhythms and prolonged nuclear PERIOD/TIMELESS expression rhythms and locomotor activity rhythms. In rat pacemaker neurons in the hypothalamic suprachiasmatic nucleus (SCN), circadian rhythms in cytosolic Ca2+ and Bmal1 transcription were dampened by Letm1 knockdown. Mitochondrial Ca2+ uptake peaks late during the day were also observed in rat SCN neurons following photolytic elevation of cytosolic Ca2+. Since cation transport by LETM1 is coupled to mitochondrial energy synthesis, we propose that LETM1 integrates metabolic, ionic, and molecular clock rhythms in the central clock system in both invertebrates and vertebrates.

Intracellular interplay between cholecystokinin and leptin signalling for satiety control in rats.

Cholecystokinin (CCK) and leptin are satiety-controlling peptides, yet their interactive roles remain unclear. Here, we addressed this issue using in vitro and in vivo models. In rat C6 glioma cells, leptin pre-treatment enhanced Ca2+ mobilization by a CCK agonist (CCK-8s). This leptin action was reduced by Janus kinase inhibitor (AG490) or PI3-kinase inhibitor (LY294002). Meanwhile, leptin stimulation alone failed to mobilize Ca2+ even in cells overexpressing leptin receptors (C6-ObRb). Leptin increased nuclear immunoreactivity against phosphorylated STAT3 (pSTAT3) whereas CCK-8s reduced leptin-induced nuclear pSTAT3 accumulation in these cells. In the rat ventromedial hypothalamus (VMH), leptin-induced action potential firing was enhanced, whereas nuclear pSTAT3 was reduced by co-stimulation with CCK-8s. To further analyse in vivo signalling interplay, a CCK-1 antagonist (lorglumide) was intraperitoneally injected in rats following 1-h restricted feeding. Food access was increased 3-h after lorglumide injection. At this timepoint, nuclear pSTAT3 was increased whereas c-Fos was decreased in the VMH. Taken together, these results suggest that leptin and CCK receptors may both contribute to short-term satiety, and leptin could positively modulate CCK signalling. Notably, nuclear pSTAT3 levels in this experimental paradigm were negatively correlated with satiety levels, contrary to the generally described transcriptional regulation for long-term satiety via leptin receptors.

Histamine Regulates Molecular Clock Oscillations in Human Retinal Pigment Epithelial Cells via H1 Receptors.

Vertebrate eyes are known to contain circadian clocks, but their regulatory mechanisms remain largely unknown. To address this, we used a cell line from human retinal pigment epithelium (hRPE-YC) with stable coexpression of reporters for molecular clock oscillations (Bmal1-luciferase) and intracellular Ca2+ concentrations (YC3.6). We observed concentration-dependent increases in cytosolic Ca2+ concentrations after treatment with histamine (1-100 µM) and complete suppression of histamine-induced Ca2+ mobilizations by H1 histamine receptor (H1R) antagonist d-chlorpheniramine (d-CPA) in hRPE-YC cells. Consistently, real-time RT-PCR assays revealed that H1R showed the highest expression among the four subtypes (H1-H4) of histamine receptors in hRPE-YC cells. Stimulation of hRPE-YC cells with histamine transiently increased nuclear localization of phosphorylated Ca2+/cAMP-response element-binding protein that regulates clock gene transcriptions. Administration of histamine also shifted the Bmal1-luciferase rhythms with a type-1 phase-response curve, similar to previous results with carbachol stimulations. Treatment of hRPE-YC cells with d-CPA or with more specific H1R antagonist, ketotifen, blocked the histamine-induced phase shifts. Furthermore, an H2 histamine receptor agonist, amthamine, had little effect on the Bmal1-luciferase rhythms. Although the function of the in vivo histaminergic system within the eye remains obscure, the present results suggest histaminergic control of the molecular clock via H1R in retinal pigment epithelial cells. Also, since d-CPA and ketotifen have been widely used (e.g., to treat allergy and inflammation) in our daily life and thus raise a possible cause for circadian rhythm disorders by improper use of antihistamines.

Comparison of dispersion behavior of agglomerated particles in liquid between ultrasonic irradiation and mechanical stirring.

The particle dispersion behavior was compared for ultrasonic irradiation and mechanical stirring. The experiment and calculation were carried out with polymethylmethacrylate (PMMA) particles. The dispersion rate of the agglomerated particles increased with the decreasing ultrasonic frequency and the increasing electric power, whereas it increased with the increasing rotation speed for the mechanical stirring. The temporal change in the particle dispersion proceeded stably after passage of a long time. The dispersion of the ultrasonic irradiation was suggested to occur by the erosion from the surface of the cluster one by one due to the bulk cavitation as well as the division into smaller particles because of the inner cavitation, and that of the mechanical stirring mainly by the division into smaller clusters due to the shear stress flow. Based on the experimental results, mathematical models for the ultrasonic irradiation and mechanical stirring were developed with the dispersion and agglomeration terms and the calculation of the temporal change in the total cluster number at the different operational factors agreed with the experiments. The dispersion efficiency of the ultrasonic irradiation was larger than that of the mechanical stirring at the lower input power, but it was reversed at the higher input power.

Physical implementation of oblivious transfer using optical correlated randomness.

We demonstrate physical implementation of information-theoretic secure oblivious transfer based on bounded observability using optical correlated randomness in semiconductor lasers driven by common random light broadcast over optical fibers. We demonstrate that the scheme can achieve one-out-of-two oblivious transfer with effective key generation rate of 110 kb/s. The results show that this scheme is a promising approach to achieve information-theoretic secure oblivious transfer over long distances for future applications of secure computation such as privacy-preserving database mining, auctions and electronic-voting.

Information-theoretic secure key distribution based on common random-signal induced synchronization in unidirectionally-coupled cascades of semiconductor lasers.

It has been proposed that a secure key distribution scheme using correlated random bit sequences can be implemented using common random-signal induced synchronization of semiconductor laser systems. In this scheme it is necessary to use laser systems consisting of multiple cascaded lasers to be secure against a powerful eavesdropper. In this paper, we report the results of an experimental study that demonstrate that the common random-signal induced synchronization is possible in cascaded semiconductor laser systems. We also show that the correlated random bit sequences generated in the synchronized cascaded laser systems can be used to create an information-theoretically secure key between two legitimate users.

Experiment on synchronization of semiconductor lasers by common injection of constant-amplitude random-phase light.

We experimentally and numerically observe the synchronization between two semiconductor lasers induced by common optical injection with constant-amplitude and random-phase modulation in configurations with and without optical feedback. Large cross correlation (~0.9) between the intensity oscillations of the two response lasers can be achieved although the correlation between the drive laser and either one of the two response lasers is very small (~0.2). High quality synchronization is achieved in the presence of optical feedback in response lasers with matched feedback phase offset. We investigate the dependence of synchronization on parameter values over wide parameter ranges.

Intranasal immunization with poly(γ-glutamic acid) nanoparticles entrapping antigenic proteins can induce potent tumor immunity.

We previously reported strong induction of ovalbumin (OVA)-specific tumor immunity in mice injected subcutaneously with OVA-entrapping nanoparticles comprising amphiphilic poly(γ-glutamic acid) (OVA/γ-PGA NPs). In the present study we investigated antitumor efficacy and associated immune responses in mice vaccinated with OVA/γ-PGA NPs via the nasal cavity. Mice vaccinated intranasally with OVA/γ-PGA NPs resisted challenge by E.G7-OVA tumor cells, and lung metastasis of B16-OVA cells were significantly suppressed by three intranasal doses of OVA/γ-PGA NPs. Although the total serum anti-OVA IgG titer was equivalent between the OVA/γ-PGA NP- and OVA solution-immunized groups, intranasal vaccination with OVA/γ-PGA NPs efficiently induced cytotoxic T lymphocytes (CTLs) and interferon-γ-secreting cells specific for OVA in the spleen and lymph nodes. The antitumor activity induced by intranasal vaccination of OVA/γ-PGA NPs mainly required CD8(+) CTLs, and the development of long-term specific immunity was confirmed in rechallenge experiments. OVA/γ-PGA NPs administered via the nasal cavity were rapidly taken up by nasopharyngeal-associated lymphoid tissue and delivered to the cervical lymph nodes. Thus, nasal vaccination with antigen-entrapping γ-PGA NPs evokes tumor immunity by eliciting antigen-specific CTLs. γ-PGA NPs are a promising antigen delivery carrier for the development of non-invasive cancer vaccines.