e Recently, we reported the discovery of three novel coronaviruses, bulbul coronavirus HKU11, thrush coronavirus HKU12, and munia coronavirus HKU13, which were identified as representatives of a novel genus, Deltacoronavirus, in the subfamily Coronavirinae. In this territory-wide molecular epidemiology study involving 3,137 mammals and 3,298 birds, we discovered seven additional novel deltacoronaviruses in pigs and birds, which we named porcine coronavirus HKU15, white-eye coronavirus HKU16, sparrow coronavirus HKU17, magpie robin coronavirus HKU18, night heron coronavirus HKU19, wigeon coronavirus HKU20, and common moorhen coronavirus HKU21. Complete genome sequencing and comparative genome analysis showed that the avian and mammalian deltacoronaviruses have similar genome characteristics and structures. They all have relatively small genomes (25.421 to 26.674 kb), the smallest among all coronaviruses. They all have a single papain-like protease domain in the nsp3 gene; an accessory gene, NS6 open reading frame (ORF), located between the M and N genes; and a variable number of accessory genes (up to four) downstream of the N gene. Moreover, they all have the same putative transcription regulatory sequence of ACACCA. Molecular clock analysis showed that the most recent common ancestor of all coronaviruses was estimated at approximately 8100 BC, and those of Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus were at approximately 2400 BC, 3300 BC, 2800 BC, and 3000 BC, respectively. From our studies, it appears that bats and birds, the warm blooded flying vertebrates, are ideal hosts for the coronavirus gene source, bats for Alphacoronavirus and Betacoronavirus and birds for Gammacoronavirus and Deltacoronavirus, to fuel coronavirus evolution and dissemination.

Microsomal NADPH-cytochrome P450 reductase (CPR) is one of only two mammalian enzymes known to contain both FAD and FMN, the other being nitric-oxide synthase. CPR is a membrane-bound protein and catalyzes electron transfer from NADPH to all known microsomal cytochromes P450. The structure of rat liver CPR, expressed in Escherichia coli and solubilized by limited trypsinolysis, has been determined by x-ray crystallography at 2.6 Å resolution. The molecule is composed of four structural domains:

Some pathogens and pests deliver small RNAs (sRNAs) into host cells to suppress host immunity. Conversely, hosts also transfer sRNAs into pathogens and pests to inhibit their virulence. Although sRNA trafficking has been observed in a wide variety of interactions, how sRNAs are transferred, especially from hosts to pathogens and pests, is still unknown. Here, we show that host cells secrete exosome-like extracellular vesicles to deliver sRNAs into fungal pathogen These sRNA-containing vesicles accumulate at the infection sites and are taken up by the fungal cells. Transferred host sRNAs induce silencing of fungal genes critical for pathogenicity. Thus, has adapted exosome-mediated cross-kingdom RNA interference as part of its immune responses during the evolutionary arms race with the pathogen.

Background Morbidity and mortality from COVID‐19 caused by novel coronavirus SARS‐CoV‐2 is accelerating worldwide, and novel clinical presentations of COVID‐19 are often reported. The range of human cells and tissues targeted by SARS‐CoV‐2, its potential receptors and associated regulating factors are still largely unknown. The aim of our study was to analyze the expression of known and potential SARS‐CoV‐2 receptors and related molecules in the extensive collection of primary human cells and tissues from healthy subjects of different age and from patients with risk factors and known comorbidities of COVID‐19. Methods We performed RNA sequencing and explored available RNA‐Seq databases to study gene expression and co‐expression of ACE2, CD147 (BSG), and CD26 (DPP4) and their direct and indirect molecular partners in primary human bronchial epithelial cells, bronchial and skin biopsies, bronchoalveolar lavage fluid, whole blood, peripheral blood mononuclear cells (PBMCs), monocytes, neutrophils, DCs, NK cells, ILC1, ILC2, ILC3, CD4+ and CD8+ T cells, B cells, and plasmablasts. We analyzed the material from healthy children and adults, and from adults in relation to their disease or COVID‐19 risk factor status. Results ACE2 and TMPRSS2 were coexpressed at the epithelial sites of the lung and skin, whereas CD147 (BSG), cyclophilins (PPIA andPPIB), CD26 (DPP4), and related molecules were expressed in both epithelium and in immune cells. We also observed a distinct age‐related expression profile of these genes in the PBMCs and T cells from healthy children and adults. Asthma, COPD, hypertension, smoking, obesity, and male gender status generally led to the higher expression of ACE2‐ and CD147‐related genes in the bronchial biopsy, BAL, or blood. Additionally, CD147‐related genes correlated positively with age and BMI. Interestingly, we also observed higher expression of CD147‐related genes in the lesional skin of patients with atopic dermatitis. Conclusions Our data suggest different receptor repertoire potentially involved in the SARS‐CoV‐2 infection at the epithelial barriers and in the immune cells. Altered expression of these receptors related to age, gender, obesity and smoking, as well as with the disease status, might contribute to COVID‐19 morbidity and severity patterns.

To investigate the seasonal characteristics of submicron aerosol (PM1) in Beijing urban areas, a high-resolution time-of-flight aerosol-mass-spectrometer (HR-ToF-AMS) was utilized at an urban site in summer (August to September 2011) and winter (November to December 2010), coupled with multiple state of the art online instruments. The average mass concentrations of PM1 (60-84 mu gm(-3)) and its chemical compositions in different campaigns of Beijing were relatively consistent in recent years. In summer, the daily variations of PM1 mass concentrations were stable and repeatable. Eighty-two percent of the PM1 mass concentration on average was composed of secondary species, where 62% is secondary inorganic aerosol and 20% secondary organic aerosol (SOA). In winter, PM1 mass concentrations changed dramatically because of the different meteorological conditions. The high average fraction (58%) of primary species in PM1 including primary organic aerosol (POA), black carbon, and chloride indicates primary emissions usually played a more important role in the winter. However, aqueous chemistry resulting in efficient secondary formation during occasional periods with high relative humidity may also contribute substantially to haze in winter. Results of past OA source apportionment studies in Beijing show 45-67% of OA in summer and 22-50% of OA in winter can be composed of SOA. Based on the source apportionment results, we found 45% POA in winter and 61% POA in summer are from nonfossil sources, contributed by cooking OA in both seasons and biomass burning OA (BBOA) in winter. Cooking OA, accounting for 13-24% of OA, is an important nonfossil carbon source in all years of Beijing and should not be neglected. The fossil sources of POA include hydrocarbon-like OA from vehicle emissions in both seasons and coal combustion OA (CCOA) in winter. The CCOA and BBOA were the two main contributors (57% of OA) for the highest OA concentrations (>100 mu gm(-3)) in winter. The POA/CO ratios in winter and summer are 11 and 16 mu gm(-3)ppm(-1), respectively, similar to ratios from western cities. Higher OOA/O-x (=NO2+O-3) ratio (0.49 mu gm(-3)ppb(-1)) in winter study than these ratios from western cities (0.03-0.16 mu gm(-3)ppb(-1)) was observed, which may be due to the aqueous reaction or extra SOA formation contributed by semivolatile organic compounds from various primary sources (e.g., BBOA or CCOA) in Beijing. The evolution of oxygen to carbon ratio (O/C) with photochemical age allows to estimate an equivalent rate constant for chemical aging of OA in summer as k(OH)similar to 4.1x10(-12)cm(3)molecule(-1)s(-1), which is of the same order as obtained in other anthropogenic influenced areas and may be useful for OA modeling

The three-dimensional strcture of mediumchain acyl-CoA dehydrogenase from pig mitochondria in the native form and that ofa complex ofthe enzyme and a strate (product) have been solved and refined by x-ray crystallo- Mammalian acyl-CoA dehydrogenases [acyl-CoA:(acceptor) 2,3-oxidoreductase; EC 1.3.99.3] catalyze the first step in each cycle of fatty acid a-oxidation in mitochondria (1).Acyl-CoA thioesters are oxidized to the corresponding trans-2,3-enoyl-CoA products with concomitant reduction of enzyme-bound FAD. Reoxidation of the dehydrogenase flavin and the transfer of reducing equivalents to the mitochondrial respiratory chain are catalyzed by the soluble electron transferring flavoprotein (ETF) and the particulate ETF-ubiquinone oxidoreductase, an iron-sulfur flavoprotein (2, 3).Three soluble stright-chain acyl-CoA dehydrogenases have been isolated and classified according to their distinct but overlapping substrate specificities for long-, medium-, and short-chain fatty acids (4). Recently, a very-long-chain acylCoA dehydrogenase has been identified in the inner membrane of rat mitochondria (5). In addition, three dehydrogenases involved in amino acid metabolism, isovaleryl-(6), 2-methyl branched chain (7), and glutaryl-(8) CoA dehydrogenases, have been isolated and characterized. With the exception of the membrane-associated very-long-chain acylCoA dehydrogenase, these enzymes appear very similar in their catalytic mechanism and their biochemical properties.They are homotetramers and each subunit contains --400 aaThe publication costs of this article were defrayed in part by page chare payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact. residues and one equivalent of FAD. Medium-chain acylCoA dehydrogenase (MCAD) exhibits a broad chain-length specificity and has its highest activity with Cg-CoA. Re-cently, several genetic diseases have been found to be due to acyl-CoA dehydrogenase deficiencies. Deficiency of MCAD appears to be the most common among disorders offatty acid oxidation in humans (9). It is manifested by fasting intolerance, hypoglycemic coma, failure of ketogenesis, dicarboxylic acidemia, and sudden infant death (10). Although the enzyme structure described in this report is that of the porcine liver enzyme, the amino acid sequence is very similar to that of the human enzyme (11), from which it differs by <10% conservative substitutions (A. W. Strauss, personal communication). Therefore, it is expected that structural conclusions drawn from the pig enzyme will apply to the human enzyme. We have reported the crystal structure of pig-liver MCAD at 3.0-A resolution (12) and preliminary data on complexes of the enzyme and substrates (13). In this paper, we present the crystal structure ofMCAD in the native form and that of a complex of the enzyme and the octanoylCoA, both refined at 2.4-A resolution.

The worldwide emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis threatens to make this disease incurable. Drug resistance mechanisms are only partially understood, and whether the current understanding of the genetic basis of drug resistance in M. tuberculosis is sufficiently comprehensive remains unclear. Here we sequenced and analyzed 161 isolates with a range of drug resistance profiles, discovering 72 new genes, 28 intergenic regions (IGRs), 11 nonsynonymous SNPs and 10 IGR SNPs with strong, consistent associations with drug resistance. On the basis of our examination of the dN/dS ratios of nonsynonymous to synonymous SNPs among the isolates, we suggest that the drug resistance-associated genes identified here likely contain essentially all the nonsynonymous SNPs that have arisen as a result of drug pressure in these isolates and should thus represent a near-complete set of drug resistance-associated genes for these isolates and antibiotics. Our work indicates that the genetic basis of drug resistance is more complex than previously anticipated and provides a strong foundation for elucidating unknown drug resistance mechanisms.

Twelve complete genomes of three novel coronaviruses-bat coronavirus HKU4 (bat-CoV HKU4), bat-CoV HKU5 (putative group 2c), and bat-CoV HKU9 (putative group 2d)-were sequenced. Comparative genome analysis showed that the various open reading frames (ORFs) of the genomes of the three coronaviruses had significantly higher amino acid identities to those of other group 2 coronaviruses than group 1 and 3 coronaviruses. Phylogenetic trees constructed using chymotrypsin-like protease, RNA-dependent RNA polymerase, helicase, spike, and nucleocapsid all showed that the group 2a and 2b and putative group 2c and 2d coronaviruses are more closely related to each other than to group 1 and 3 coronaviruses. Unique genomic features distinguishing between these four subgroups, including the number of papain-like proteases, the presence or absence of hemagglutinin esterase, small ORFs between the membrane and nucleocapsid genes and ORFs (NS7a and NS7b), bulged stem-loop and pseudoknot structures downstream of the nucleocapsid gene, transcription regulatory sequence, and ribosomal recognition signal for the envelope gene, were also observed. This is the first time that NS7a and NS7b downstream of the nucleocapsid gene has been found in a group 2 coronavirus. The high Ka/Ks ratio of NS7a and NS7b in bat-CoV HKU9 implies that these two group 2d-specific genes are under high selective pressure and hence are rapidly evolving. The four subgroups of group 2 coronaviruses probably originated from a common ancestor. Further molecular epidemiological studies on coronaviruses in the bats of other countries, as well as in other animals, and complete genome sequencing will shed more light on coronavirus diversity and their evolutionary histories.