Aims: To evaluate the antioxidant effect of carotenoids from Deinococcus radiodurans on protein. Methods and Results: Deinococcus radiodurans strain R1 (ATCC 13939) and its mutant strain R1ΔcrtB were used for this study. The total carotenoids (R1ex) from D. radiodurans were obtained by extraction with acetone/methanol (7 : 2, by vol), and their antioxidant activity was measured using the DPPH˙ (2,2‐diphenyl‐1‐picrylhydrazyl) system. The protein oxidation level, in vitro and in the cell, was measured using the DNPH (2,4‐dinitrophenyl hydrazine) method. The carotenoid extract R1ex scavenged 40·2% DPPH˙ radicals compared to β‐carotene (31·7%) at a concentration of 0·5 mg ml−1. The intracellular level of protein oxidation in mutant R1ΔcrtB, which does not contain carotenoid, was 0·0212 mmol mg−1 protein which is significantly greater than that in the wild type (0·0169 mmol mg−1 protein) following the treatment with H2O2. The purified major carotenoid product (deinoxanthin) from the wild type showed a greater inhibition of oxidative damage in bovine serum albumin than lycopene or lutein. Conclusions: Carotenoids prevent protein oxidation and contribute to the resistance to cell damage in D. radiodurans. Significance and Impact of the Study: Our results provide the evidence that carotenoids can protect proteins in D. radiodurans against oxidative stress.
While major progress has been made in the research of inertial confinement fusion, significant challenges remain in the pursuit of ignition. To tackle the challenges, we propose a double-cone ignition (DCI) scheme, in which two head-on gold cones are used to confine deuterium–tritium (DT) shells imploded by high-power laser pulses. The scheme is composed of four progressive controllable processes: quasi-isentropic compression, acceleration, head-on collision and fast heating of the compressed fuel. The quasi-isentropic compression is performed inside two head-on cones. At the later stage of the compression, the DT shells in the cones are accelerated to forward velocities of hundreds of km s –1 . The head-on collision of the compressed and accelerated fuels from the cone tips transfer the forward kinetic energy to the thermal energy of the colliding fuel with an increased density. The preheated high-density fuel can keep its status for a period of approximately 200 ps. Within this period, MeV electrons generated by ps heating laser pulses, guided by a ns laser-produced strong magnetic field further heat the fuel efficiently. Our simulations show that the implosion inside the head-on cones can greatly mitigate the energy requirement for compression; the collision can preheat the compressed fuel of approximately 300 g cm −3 to a temperature above keV. The fuel can then reach an ignition temperature of greater than 5 keV with magnetically assisted heating of MeV electrons generated by the heating laser pulses. Experimental campaigns to demonstrate the scheme have already begun. This article is part of a discussion meeting issue ‘Prospects for high gain inertial fusion energy (part 1)’.
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