Design of Strain-Sensing Devices in Microscale by Using Surface Plasmon Polaritons

We have presented a strain-sensing device in microscale by using surface plasmon polaritons and multimode interference effects. The device is numerically investigated by the finite-difference time-domain method. Optimum depths and length of the structure are designed for sensing a strain. The size of the designed structure is several micrometers and is about a thousandth compared with a fiber Bragg grating strain sensor. The sensitivity of the designed structure is 11.34 pm/μ?? that is about ten times larger than that of a fiber Bragg grating strain sensor. The temperature sensitivity of the designed structure is 34.43 pm/ ^°C. This temperature sensitivity is three times larger than that of a fiber Bragg grating strain sensor. Therefore, temperature compensation techniques are needed for the structure. The presented structure has a simple design such as a plasmonic waveguide with a trench structure. The simple structural design device has a capability of being used in micro- and nano-electromechanical systems.     

P2X7 ionotropic receptor is functionally expressed in rabbit articular chondrocytes and mediates extracellular ATP cytotoxicity

Extracellular ATP regulates various cellular functions by engaging multiple subtypes of P2 purinergic receptors. In many cell types, the ionotropic P2X7 receptor mediates pathological events such as inflammation and cell death. However, the importance of this receptor in chondrocytes remains largely unexplored. Here, we report the functional identification of P2X7 receptor in articular chondrocytes and investigate the involvement of P2X7 receptors in ATP-induced cytotoxicity. Chondrocytes were isolated from rabbit articular cartilage, and P2X7 receptor currents were examined using the whole-cell patch-clamp technique. ATP-induced cytotoxicity was evaluated by measuring caspase-3/7 activity, lactate dehydrogenase (LDH) leakage, and prostagrandin E₂ (PGE₂) release using microscopic and fluorimetric/colorimetric evaluation. Extracellular ATP readily evoked a cationic current without obvious desensitization. This ATP-activated current was dose related, but required millimolar concentrations. A more potent P2X7 receptor agonist, BzATP, also activated this current but at 100-fold lower concentrations. ATP-induced currents were largely abolished by selective P2X7 antagonists, suggesting a predominant role for the P2X7 receptor. RT-PCR confirmed the presence of P2X7 in chondrocytes. Heterologous expression of a rabbit P2X7 clone successfully reproduced the ATP-induced current. Exposure of chondrocytes to ATP increased caspase-3/7 activities, an effect that was totally abrogated by P2X7 receptor antagonists. Extracellular ATP also enhanced LDH release, which was partially attenuated by the P2X7 inhibitor. The P2X7 receptor-mediated elevation in apoptotic caspase signaling was accompanied by increased PGE₂ release and was attenuated by inhibition of either phospholipase A₂ or cyclooxygenase-2. This study provides direct evidence for the presence of functional P2X7 receptors in articular chondrocytes. Our results suggest that the P2X7 receptor is a potential therapeutic target in chondrocyte death associated with cartilage injury and disorders including osteoarthritis.     

Diazirine-containing tag-free RNA probes for efficient RISC-loading and photoaffinity labeling of microRNA targets

We designed and synthesized a photo-reactive and tag-free RNA probe for the identification of microRNA (miRNA) targets. To synthesize the RNA probe, we designed a novel nucleoside analog 1-O-[3-ethynyl-5-(3-trifluoromethyl-3H-diazirine-3-yl)]benzyl-β-d-ribofuranose containing aryl trifluoromethyl diazirine and ethynyl moieties. The RNA probe containing this analog was observed to form crosslinks with complementary RNA by UV irradiation and was rapidly tagged by Cu-catalyzed azide alkyne cycloaddition (CuAAC). In addition, the tag-free and photo-reactive miRNA-145 probe showed comparable gene silencing activity to that of unmodified miRNA-145. Therefore, miRNA probes containing the nucleoside analog are promising candidates for the identification of target mRNAs of miRNAs.     

Identification of the protocatechuate transporter gene in Sphingobium sp. strain SYK-6 and effects of overexpression on production of a value-added metabolite

Applied Microbiology and Biotechnology - Sphingobium sp. strain SYK-6 expresses the best characterized catabolic systems for lignin-derived aromatic compounds. However, the uptake systems for these...     

Imaging mass spectroscopy delineates the thinned and thickened walls of intracranial aneurysms

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The wall thickness of intracranial aneurysms (IAs) is heterogeneous. Although thinning of the IA wall is thought to contribute to IA rupture, the underlying mechanism remains poorly understood. Recently, imaging mass spectroscopy (IMS) has been used to reveal the distribution of phospholipids in vascular diseases. To investigate the feature of phospholipid composition of IA walls, we conducted IMS in a rat model of experimentally induced IA.

Environmental control of the seasonal life cycle of a zoophytophagous mirid, <Emphasis Type="Italic">Adelphocoris triannulatus</Emphasis> (Hemiptera: Miridae)

Adelphocoris triannulatus (Stål) (Heteroptera: Miridae) is a zoophytophagous bug that inhabits grasslands and crop fields, and is widely distributed in eastern Asia. In this study, the seasonal occurrence and environmental factors controlling the seasonal life cycle of this bug were investigated in a local population in southern Kyushu, Japan. When insects were reared under different photoperiods at 20 and 25 °C, they produced diapause or nondiapause eggs depending on the photoperiod: when reared under short-day photoperiods (≤?13 h/day), females laid diapause eggs, whereas they laid nondiapause eggs when reared under long-day photoperiods (≥?14 h/day). Because the developmental duration of the pre-adult stages and maturation (minimum duration of one generation) is estimated to be approximately 30 days at summer temperatures, these results suggest that this bug has a multivoltine seasonal life cycle. In agreement with the laboratory results, only nondiapause eggs were produced until mid-August in the field, and an increasing proportion of diapause eggs were produced from early September. In addition to these findings, field sampling from spring to autumn in 2009 indicated that three or four generations were produced in one year. These results suggest that egg diapause plays a role in preventing nymphs of A. triannulatus from developing in winter, and thereby ensures the survival of the population in adverse seasons.     

Activation of prothrombin by two subtilisin-like serine proteases from Acremonium sp

Two novel subtilisin-like serine proteases (AS-E1 and -E2) that activate prothrombin have been identified in a culture of the fungus Acremonium sp. The enzymes were purified through repeated hydrophobic interaction chromatography. The N-terminal sequences of AS-E1 (34.4 kDa) and AS-E2 (32 kDa) showed high similarity to the internal sequences of two distinct subtilisin-like hypothetical proteins from Chaetomium globosum. Both enzymes proteolytically activated prothrombin to meizothrombin(desF1)-like molecules, while the activation cleavage seemed to occur at a site (Tyr(316)-Ile(317)) that is four residues proximal to the canonical Xa cleavage site (Arg(320)-Ile(321)). Both enzymes inhibited plasma clotting, possibly due to extensive degradation of fibrinogen and production of meizothrombin(desF1)-like molecule.     

Expression of the Na+-K+-2Cl- cotransporter in the rat endolymphatic sac

The endolymphatic sac (ES) is a part of the membranous labyrinth that contains the cochlea, vestibular organs, and semicircular canals, and is believed to absorb endolymphatic fluid. Na⁺–K⁺–2Cl⁻ (NKCC) is a cotransporter that occurs as two isoforms (NKCC-1 and NKCC-2). Especially, NKCC-2 is suggested to participate in ES endolymph absorption. In the present study, the expression and cellular localization of NKCC-1 and NKCC-2 in the rat ES were examined by RT-PCR and in situ hybridization, respectively. The findings indicate that both NKCC-1 and NKCC-2 are expressed in the rat ES and suggest that NKCC is involved in ES homeostasis. NKCC-2 may be particularly involved in endolymph absorption. This is the first report confirming NKCC expression in the ES.     

Geographical variation in the early regeneration process of Siebold's Beech (Fagus crenata BLUME) in Japan

The causes and timing of seed death in early regeneration process of Siebold's beech (Fagus crenata Blume) was studied at 15 sites along a snowfall gradient in Japan, in order to clarify why the seedling density of the species has geographic difference remarkably. Seed production did not significantly differ along the snowfall gradient. Pre-dispersal seed mortality by insect damage was higher at sites with light snowfall than at sites with heavy snowfall, but this only seemed to be a minor factor influencing the population. A large proportion of the viable nuts that fall in autumn ware killed in winter before germination. Winter mortality was much higher at sites with thin snow cover than that at sites with thick snow cover, and this factor was strongly correlated with the geographic variation of seedling regeneration probability. There was little seed mortality by winter desiccation. The main factor contributing to the geographic difference seemed to be a seed predation by rodents in winter. Deep snow cover may reduce the success of rodents finding seeds in winter. Thus the observed relationship between snowpack depth and early mortality may be due to an indirect effect through the process of seed predation.p>