Yiming Wu

NH3 OBSERVATIONS OF THE INFRARED DARK CLOUD G28.34+0.06

We present observations of the NH3 (J, K) = (1, 1) and (2, 2) inversion transitions toward the infrared dark cloud G28.34+0.06, using the Very Large Array. Strong NH3 emission is found to coincide well with the infrared absorption feature in this cloud. The northern region of G28.34+0.06 is dominated by a compact clump (P2) with a high rotation temperature (29 K) and large line width (4.3 km s−1), and is associated with a strong water maser (240 Jy) and a 24 μm point source with far-IR luminosity of 103 L☉. We infer that P2 has embedded massive protostars although it lies in the 8 μm absorption region. The southern region has filamentary structures. The rotation temperature in the southern region decreases with the increase of the integrated NH3 intensity, which indicates an absence of strong internal heating in these clumps. In addition, the compact core P1 in the south has small line width (1.2 km s−1) surrounded by extended emission with larger line width (1.8 km s−1), which suggests a dissipation of turbulence in the dense part of the cloud. Thus, we suggest that P1 is at a much earlier evolutionary stage than P2, possibly at a stage that begins to form a cluster with massive stars.

Ammonia cores in high mass star formation regions

We observed a sample of 35 water masers not coincident with known HII regions and/or low mass young stellar objects (YSOs) with the Effelsberg 100 m telescope in the NH3(J,K) = (1,1), (2,2), (3,3) and (4,4) transitions. Sixteen sources were detected in the NH3 emission. The detection rate is 46%. All these sixteen sources have NH3 (1,1) and (2,2) emission, among which four sources have NH3 (3,3) emission. Comparing with the IRAS and the 2MASS data, we analyzed the relationship between the detection rate and the infrared color, the dust temperature and the source distance. All the detected sources were mapped and 17 cores were obtained (one source IRAS 20215+3725 has two cores). From the detected sources five cores do not coincide with radio continuum or IRAS and MSX point sources. Excluding one core that has no MSX data available, the remaining eleven cores are coincident with IRAS or MSX point sources. The typical size and mass of the cores are 1.6 pc and 1.5 x 10(3) M-circle dot, respectively. The average line widths of the NH3 (1,1) and (2,2) are 1.54 and 1.73 km s(-1). The average kinetic temperature of the gas is about 19 K. These values are much larger than those of low mass cores. The NH3 cores that coincide with IRAS sources (referred to as Group I) have slightly larger line widths (1.65 and 1.75 km s(-1) for the (1,1) and (2,2) lines, respectively) and larger masses (1.8 x 10(3) M-circle dot) than the mean values of the sample. For this type of core the kinetic temperature correlates with the line width. The line width appears to correlate with the bolometric luminosity and the core size. Despite the average luminosity of 2.9 x 10(4) L-circle dot, there is no detectable 6 cm emission. These are candidates for high mass protostars or precursors of UC HII regions. The NH3 cores with peaks onset from infrared sources (referred to as Group II) have an average size of 1.7 pc and an average line width of 1.50 km s(-1) for the (1,1) line. The line width of the (1,1) emission is smaller than that of the group I. The average mass is 9.4 x 10(2) M-circle dot. One possible explanation for the deviation is that the NH3 peak and the infrared source correspond to different clumps. These cores are potential high mass star formation sites and may be at an earlier evolutionary stage than those with IRAS point sources. This type of core is seen in mapping observations, and can be easily missed by single-spectrum observations toward the IRAS position.

Discovery of pentacyclic triterpenoids as potential entry inhibitors of influenza viruses.

Entry inhibitors are of particular importance in current efforts to develop a new generation of anti-influenza virus drugs. Here we report certain pentacyclic triterpenes exhibiting conserved structure features and with in vitro anti-influenza virus activity comparable to and even higher than that of oseltamivir. Mechanistic studies indicated that these lead triterpenoids bind tightly to the viral envelope hemagglutinin (HA), disrupting the interaction of HA with the sialic acid receptor and thus the attachment of viruses to host cells. Docking studies suggest that the binding pocket within HA for sialic acid receptor potentially acts as a targeting domain, and this is supported by structure-activity data, sialic acid competition studies, and broad anti-influenza spectrum as well as less induction of drug resistance. Our study might establish the importance of triterpenoids for development of entry inhibitors of influenza viruses.

Generation of influenza A viruses as live but replication-incompetent virus vaccines

Genetic code expansion and orthogonal translation machinery are used to generate live, attenuated viral vaccines. Protecting by changing the code Live attenuated vaccines can be very potent, but their potential to revert to their pathogenic form limits their use. In an attempt to get around this, Si et al. expanded the genetic code of influenza A viruses. They propagated viruses that were mutated to encode premature termination codons (PTCs) in a cell line engineered to be able to express these flu proteins. Despite not being able to replicate in conventional cells, PTC-containing viruses were highly immunogenic and protected mice, guinea pigs, and ferrets against influenza challenge. Science, this issue p. 1170 The conversion of life-threatening viruses into live but avirulent vaccines represents a revolution in vaccinology. In a proof-of-principle study, we expanded the genetic code of the genome of influenza A virus via a transgenic cell line containing orthogonal translation machinery. This generated premature termination codon (PTC)–harboring viruses that exerted full infectivity but were replication-incompetent in conventional cells. Genome-wide optimization of the sites for incorporation of multiple PTCs resulted in highly reproductive and genetically stable progeny viruses in transgenic cells. In mouse, ferret, and guinea pig models, vaccination with PTC viruses elicited robust humoral, mucosal, and T cell–mediated immunity against antigenically distinct influenza viruses and even neutralized existing infecting strains. The methods presented here may become a general approach for generating live virus vaccines that can be adapted to almost any virus.

A search for massive dense cores with

This paper reports 13 CO

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-0 line observations toward 107 IRAS or H 2 O maser sources with the 13.7 m telescope of the Purple Mountain Observatory (PMO). Parameters of emission components are obtained and the profile characteristics are identified. For all the components, kinematic distances are derived. The bolometric luminosities of the corresponding IRAS sources are calculated for 95 sources, all of which are larger than 10 3

Broadening the versatility of lentiviral vectors as a tool in nucleic acid research via genetic code expansion

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Development of next generation of therapeutic IFN-α2b via genetic code expansion.

. We also mapped eight sources. Results show that there are cores in the clouds. The sizes of the cores are about 1~3 pc, much greater and more extensive than those of cores in dark clouds. The hydrogen densities are ~10 2 -10 3 cm -3 . Systematic velocity shifts were found in 3 sources. Every mapped core contains one or more IRAS source. Each core has one and only one IRAS source that satisfies the criteria of ultra compact HII (UC HII) regions. For the cores, 2MASS data are available; dozens of 2MASS sources with different color indices and brightness are found within the core.

VLA NH3 observations of regions of massive star formation in protostellar cores

With the aim of broadening the versatility of lentiviral vectors as a tool in nucleic acid research, we expanded the genetic code in the propagation of lentiviral vectors for site-specific incorporation of chemical moieties with unique properties. Through systematic exploration of the structure–function relationship of lentiviral VSVg envelope by site-specific mutagenesis and incorporation of residues displaying azide- and diazirine-moieties, the modifiable sites on the vector surface were identified, with most at the PH domain that neither affects the expression of envelope protein nor propagation or infectivity of the progeny virus. Furthermore, via the incorporation of such chemical moieties, a variety of fluorescence probes, ligands, PEG and other functional molecules are conjugated, orthogonally and stoichiometrically, to the lentiviral vector. Using this methodology, a facile platform is established that is useful for tracking virus movement, targeting gene delivery and detecting virus–host interactions. This study may provide a new direction for rational design of lentiviral vectors, with significant impact on both basic research and therapeutic applications.