The gene product Murr1 restricts HIV-1 replication in resting CD4+ lymphocytes

Although human immunodeficiency virus-1 (HIV-1) infects quiescent and proliferating CD4+ lymphocytes, the virus replicates poorly in resting T cells. Factors that block viral replication in these cells might help to prolong the asymptomatic phase of HIV infection; however, the molecular mechanisms that control this process are not fully understood. Here we show that Murr1, a gene product known previously for its involvement in copper regulation, inhibits HIV-1 growth in unstimulated CD4+ T cells. This inhibition was mediated in part through its ability to inhibit basal and cytokine-stimulated nuclear factor (NF)-kappaB activity. Knockdown of Murr1 increased NF-kappaB activity and decreased IkappaB-alpha concentrations by facilitating phospho-IkappaB-alpha degradation by the proteasome. Murr1 was detected in CD4+ T cells, and RNA-mediated interference of Murr1 in primary resting CD4+ lymphocytes increased HIV-1 replication. Through its effects on the proteasome, Murr1 acts as a genetic restriction factor that inhibits HIV-1 replication in lymphocytes, which could contribute to the regulation of asymptomatic HIV infection and the progression of AIDS.     

Molecular fingerprinting with the resolved modes of a femtosecond laser frequency comb

The control of the broadband frequency comb emitted from a mode-locked femtosecond laser has permitted a wide range of scientific and technological advances--ranging from the counting of optical cycles for next-generation atomic clocks to measurements of phase-sensitive high-field processes. A unique advantage of the stabilized frequency comb is that it provides, in a single laser beam, about a million optical modes with very narrow linewidths and absolute frequency positions known to better than one part in 10(15) (ref. 5). One important application of this vast array of highly coherent optical fields is precision spectroscopy, in which a large number of modes can be used to map internal atomic energy structure and dynamics. However, an efficient means of simultaneously identifying, addressing and measuring the amplitude or relative phase of individual modes has not existed. Here we use a high-resolution disperser to separate the individual modes of a stabilized frequency comb into a two-dimensional array in the image plane of the spectrometer. We illustrate the power of this technique for high-resolution spectral fingerprinting of molecular iodine vapour, acquiring in a few milliseconds absorption images covering over 6 THz of bandwidth with high frequency resolution. Our technique for direct and parallel accessing of stabilized frequency comb modes could find application in high-bandwidth spread-spectrum communications with increased security, high-resolution coherent quantum control, and arbitrary optical waveform synthesis with control at the optical radian level.