Effect of polymorphism in Rhinolophus affinis ACE2 on entry of SARS-CoV-2 related bat coronaviruses.

Bat coronavirus RaTG13 shares about 96.2% nucleotide sequence identity with that of SARS-CoV-2 and uses human and Rhinolophus affinis (Ra) angiotensin-converting enzyme 2 (ACE2) as entry receptors. Whether there are bat species other than R. affinis susceptible to RaTG13 infection remains elusive. Here, we show that, among 18 different bat ACE2s tested, only RaACE2 is highly susceptible to transduction by RaTG13 S pseudovirions, indicating that the bat species harboring RaTG13 might be very limited. RaACE2 has seven polymorphic variants, RA-01 to RA-07, and they show different susceptibilities to RaTG13 S pseudovirions transduction. Sequence and mutagenesis analyses reveal that residues 34, 38, and 83 in RaACE2 might play critical roles in interaction with the RaTG13 S protein. Of note, RaACE2 polymorphisms have minimal effect on S proteins of SARS-CoV-2 and several SARS-CoV-2 related CoVs (SC2r-CoVs) including BANAL-20-52 and BANAL-20-236 in terms of binding, membrane fusion, and pseudovirus entry. Further mutagenesis analyses identify residues 501 and 505 in S proteins critical for the recognition of different RaACE2 variants and pangolin ACE2 (pACE2), indicating that RaTG13 might have not been well adapted to R. affinis bats. While single D501N and H505Y changes in RaTG13 S protein significantly enhance the infectivity and minimize the difference in susceptibility among different RaACE2 variants, an N501D substitution in SARS-CoV-2 S protein displays marked disparity in transduction efficiencies among RaACE2 variants with a significant reduction in infectivity on several RaACE2 variants. Finally, a T372A substitution in RaTG13 S protein not only significantly increases infectivity on all RaACE2 variants, but also markedly enhances entry on several bat ACE2s including R. sinicus YN, R. pearsonii, and R. ferrumeiqunum. However, the T372A mutant is about 4-fold more sensitive to neutralizing sera from mice immunized with BANAL-20-52 S, suggesting that the better immune evasion ability of T372 over A372 might contribute to the natural selective advantage of T372 over A372 among bat CoVs. Together, our study aids a better understanding of coronavirus entry, vaccine design, and evolution.

First Known Human Death After Infection With the Avian Influenza A/H3N8 Virus: Guangdong Province, China, March 2023.

Here, we report on a case of human infection with the H3N8 avian influenza virus. The patient had multiple myeloma and died of severe infection. Genome analysis showed multiple gene mutations and reassortments without mammalian-adaptive mutations. This suggests that avian influenza (A/H3N8) virus infection could be lethal for immunocompromised persons.

Marinobacter panjinensis sp. nov., a moderately halophilic bacterium isolated from sea tidal flat environment.

Two moderately halotolerant bacterium strains, designated PJ-16T and PJ-38, were isolated from a tidal flat of the red beach in Panjin City, Liaoning Province, PR China. Cells were found to be Gram-stain-negative, aerobic, motile, rod-shaped with a single polar flagellum. Optimum growth of strain PJ-16T occurred at 30 °C, pH 7.0 and 0.2-8.0  % (w/v) NaCl, and strain PJ-38 at 30 °C, pH 6.0-7.0 and 0.2-8.0  % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain PJ-16T was most closely related to Marinobacter denitrificans KCTC 62941T (99.2 % 16S rRNA gene sequence similarity), Marinobacter algicola DSM 16394T (98.6 %), Marinobacter salarius JCM 19399T (98.4 %) and Marinobacter confluentis KCTC 42705T (98.2 %), and strain PJ-38 was most closely related to M. denitrificans KCTC 62941T (99.1 %), M. algicola DSM 16394T (98.6 %), M. salarius JCM 19399T (98.4 %) and M. confluentis KCTC 42705T (98.1 %). The G+C content of the genomic DNA of strain PJ-16T based on its draft genomic sequence was 57.4 mol%. The major cellular fatty acids of strain PJ-16T were C16 : 0, C16 : 1 ω7c/C16 : 1 ω6c and C18 : 1 ω9c. The major respiratory quinone of PJ-16T was ubiquinone-9 and the major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The results of the phenotypic, phylogenetic and genomic analyses revealed that strains PJ-16T and PJ-38 represent a novel species of the genus Marinobacter, and the name Marinobacter panjinensis sp. nov. is proposed. The type strain is PJ-16T (= CGMCC 1.13694T= KCTC 72023T).

Transmission dynamics and epidemiological characteristics of SARS-CoV-2 Delta variant infections in Guangdong, China, May to June 2021.

BackgroundThe Delta variant of SARS-CoV-2 had become predominant globally by November 2021.AimWe evaluated transmission dynamics and epidemiological characteristics of the Delta variant in an outbreak in southern China.MethodsData on confirmed COVID-19 cases and their close contacts were retrospectively collected from the outbreak that occurred in Guangdong, China in May and June 2021. Key epidemiological parameters, temporal trend of viral loads and secondary attack rates were estimated. We also evaluated the association of vaccination with viral load and transmission.ResultsWe identified 167 patients infected with the Delta variant in the Guangdong outbreak. Mean estimates of latent and incubation period were 3.9 days and 5.8 days, respectively. Relatively higher viral load was observed in infections with Delta than in infections with wild-type SARS-CoV-2. Secondary attack rate among close contacts of cases with Delta was 1.4%, and 73.1% (95% credible interval (CrI): 32.9-91.4) of the transmissions occurred before onset. Index cases without vaccination (adjusted odds ratio (aOR): 2.84; 95% CI: 1.19-8.45) or with an incomplete vaccination series (aOR: 6.02; 95% CI: 2.45-18.16) were more likely to transmit infection to their contacts than those who had received the complete primary vaccination series.DiscussionPatients infected with the Delta variant had more rapid symptom onset compared with the wild type. The time-varying serial interval should be accounted for in estimation of reproduction numbers. The higher viral load and higher risk of pre-symptomatic transmission indicated the challenges in control of infections with the Delta variant.

Silicate-clad heavily Yb3+ doped phosphate core multimaterial fiber with a high gain per unit length for mode-locked fiber laser applications.

Silicate-clad heavily Yb3+ doped phosphate core multimaterial fiber (MF) was successfully drawn by using a molten core method, which has a high gain per unit length of 5.44 dB/cm at 1.06 µm. What is more, an all-fiber-integrated passively mode-locked fiber laser based on a 5 cm long MF was built. The mode-locked pulses operate at 1055 nm with a period of ∼555ps, and the fundamental repetition rate is 1.787 GHz. For the first time, to the best of our knowledge, we demonstrate the realization of a mode-locked fiber laser with a gigahertz fundamental repetition rate based on a silicate-clad heavily Yb3+ doped phosphate core MF.

Probable Evidence of Fecal Aerosol Transmission of SARS-CoV-2 in a High-Rise Building.

BACKGROUND: The role of fecal aerosols in the transmission of severe acute respiratory syndrome coronavirus 2 has been suspected. OBJECTIVE: To investigate the temporal and spatial distributions of 3 infected families in a high-rise apartment building and examine the associated environmental variables to verify the role of fecal aerosols. DESIGN: Epidemiologic survey and quantitative reverse transcriptase polymerase chain reaction analyses on throat swabs from the participants; 237 surface and air samples from 11 of the 83 flats in the building, public areas, and building drainage systems; and tracer gas released into bathrooms as a surrogate for virus-laden aerosols in the drainage system. SETTING: A high-rise apartment building in Guangzhou, China. PARTICIPANTS: 9 infected patients, 193 other residents of the building, and 24 members of the building's management staff. MEASUREMENTS: Locations of infected flats and positive environmental samples, and spread of virus-laden aerosols. RESULTS: 9 infected patients in 3 families were identified. The first family had a history of travel to the coronavirus disease 2019 (COVID-19) epicenter Wuhan, whereas the other 2 families had no travel history and a later onset of symptoms. No evidence was found for transmission via the elevator or elsewhere. The families lived in 3 vertically aligned flats connected by drainage pipes in the master bathrooms. Both the observed infections and the locations of positive environmental samples are consistent with the vertical spread of virus-laden aerosols via these stacks and vents. LIMITATION: Inability to determine whether the water seals were dried out in the flats of the infected families. CONCLUSION: On the basis of circumstantial evidence, fecal aerosol transmission may have caused the community outbreak of COVID-19 in this high-rise building. PRIMARY FUNDING SOURCE: Key-Area Research and Development Program of Guangdong Province and the Research Grants Council of Hong Kong.

Discovery and Biosynthesis of Pepticinnamins G-M Featuring Three Enzymes-Catalyzed Nonproteinogenic Amino Acid Formation.

Since pepticinnamin E was discovered almost 30 years ago, no other pepticinnamin family of natural products has been reported to date. Here, we report the discovery of pepticinnamins G-I (1-3) from a marine Streptomyces sp. PKU-MA01144 and pepticinnamins J-M (4-7) from several mutants, and these new compounds contain different N-methyl-l-alanine and l-tyrosine residues compared to pepticinnamin E. Genome sequencing, heterologous expression, gene deletion, and reconstitution of enzymatic reaction in vitro identified the biosynthetic gene cluster of 1-7 and first experimentally established the biosynthesis of the nonproteinogenic 2-chloro-3-hydroxy-4-methoxy-l-phenylalanine residue by a biopterin-dependent hydroxylase Pep10, an O-methyltransferase Pep9, and a flavin-dependent halogenase Pep1. The biosynthetic research and heterologous expression system in this study set the stage for pathway engineering for more pepticinnamins generation in the future.

Strepimidazoles A-G from the Plant Endophytic Streptomyces sp. PKU-EA00015 with Inhibitory Activities against a Plant Pathogenic Fungus.

Seven new 4-acyl-2-aminoimidazoles, designated strepimidazoles A-G (1-7), were discovered from the endophytic Streptomyces sp. PKU-EA00015 isolated from Salvia miltiorrhiza Bunge, whose dry root "Danshen" is one of the most widely used traditional Chinese medicines. The resonance signals of the 2-aminoimidazole moiety in 1-7 were absent in the NMR spectra due to tautomerization, and the structures of 1-7 were identified after preparation of their acetylation products 1a-7a, respectively. Compounds 1-7 represent a new family of 2-aminoimidazole-containing natural products, enriching the structural diversity of natural products from endophytic origin. Compounds 1-7 showed different degrees of inhibitory activities against the plant pathogenic fungus Verticillium dahliae V991, revealing structure-activity relationships on the acyl moieties. The plant pathogenic fungus V. dahliae has been confirmed to cause serious chlorosis of cultivated S. miltiorrhiza Bunge in China. This study opens the door for further investigation of mutualistic relationships between S. miltiorrhiza Bunge and their endophytic actinomycetes and for possible antifungal agent development for biological control of V. dahliae in the future.

Oxytrodiflavanone A and Oxytrochalcoflavanones A,B: New Biflavonoids from Oxytropis chiliophylla.

Three previously undescribed biflavonoids, oxytrodiflavanone A (1), and oxytrochalcoflavanones A,B (2,3), were isolated from the aerial part of Oxytropis chiliophylla, together with their putative biosynthetic monomers, i.e., (2S)-5,7-dihydroxyflavanone (4), (2S)-7-hydroxyflavanone (5), and 2',4'-dihydroxychalcone (6). The structures of these compounds were elucidated by a combination analysis of spectroscopic data. The cytotoxic activities of all the isolated compounds against PC-3 human prostate cancer cell line are also presented.

[Characteristic fingerprint and multi-components quantitative determination for Fuke Qianjin Capsules by HPLC].

To establish an HPLC characteristic fingerprint method of Fuke Qianjin Capsules,and determine the contents of its main components. The analysis was carried out on a Kromasil 100-5-C18 analytical column(4. 6 mm ×250 mm,5 µm) with gradient elution by acetonitrile(A)-0. 1% phosphoric acid aqueous solution(B),a flow rate at 1. 0 m L·min-1 and the detection wavelength of 254 nm.The column temperature was 30 ℃,and the injection volume was 10 µL. The determination method of genistin,jatrorrhizine,andrographolide and 14-deoxy-11,12-didehydroandrographolide index components were studied methodologically. The common mode of the characteristic fingerprint of Fuke Qianjin Capsules was set up with 8 common peaks,which were identified as genistin,jatrorrhizine,palmatine,berberine,andrographolide,14-deoxy-11,12-didehydroandrographolide,Z-ligustilide,and Z-3-butylidenephthalide,respectively,in comparison with the references. The similarities of 20 batches of Fuke Qianjin Capsules samples were above 0. 95. All of the above-mentioned 4 analytes could be well separated under the optimized chromatographic conditions. RSD of precision and repeatability experiment were both less than 1. 5%,and the sample solution was stable during 72 h. All of the compounds had a good linearity and linear range. The contents of genistin,jatrorrhizine,andrographolide,and 14-deoxy-11,12-didehydroandrographolide in 20 batches of Fuke Qianjin Capsules samples were 28. 66-56. 04,94. 77-197. 92,1 705. 33-4 148. 93 and 462. 16-1 225. 96 µg in each capsule,respectively. The developed HPLC characteristic fingerprint and quantitative analysis methods were reliable,accurate and sensitive,and could be used effectively evaluate the quality of Fuke Qianjin Capsules samples.

Structurally Diverse Cytotoxic Dimeric Chalcones from Oxytropis chiliophylla.

Ten isomeric cyclobutane- and cyclohexene-containing chalcone dimers, oxyfadichalcones A-G, were isolated from the aerial parts of Oxytropis chiliophylla. These included six new compounds and three pairs of enantiomers that are being reported from natural sources for the first time. The relative configurations were elucidated by spectroscopic data analysis, while the absolute configurations were determined by comparing the experimental and calculated electronic circular dichroism spectra. Quantitative LC-MS analysis of the main dimers from different parts of the plant revealed their characteristic accumulation in the viscous secretion and provided supporting evidence for the hypothesized photochemical biosynthesis. In addition, the cytotoxic activities of all isolates against the PC-3 human prostate cancer cell line are reported.

Fluostatins M-Q Featuring a 6-5-6-6 Ring Skeleton and High Oxidized A-Rings from Marine Streptomyces sp. PKU-MA00045.

Aromatic polyketides from marine actinomycetes have received increasing attention due to their unusual structures and potent bioactivities. Compared to their terrestrial counterparts, marine aromatic polyketides have been less discovered and their structural and biological diversities are far from being fully investigated. In this study, we employed a PCR-based genome mining method to discover aromatic polyketides in our marine bacteria collection. Five new atypical angucyclinones, fluostatins M-Q (1-5) featuring a unique 6-5-6-6 ring skeleton, were discovered from one "positive" Streptomyces sp. PKU-MA00045. The structures of fluostatins M-Q (1-5) were elucidated based on comprehensive spectroscopic analyses and the crystallographic structure of fluostatin P (4), which contains the most oxidized A-ring, was solved by X-ray diffraction analysis with Cu Kα radiation. Compared to the published 16 fluostatin analogues, fluostatins M-Q (1-5) contained a different methoxy group attached at C-7 and hydroxy group attached at C-4, enriching the structural diversity of aromatic polyketides from marine actinomycetes. Genome sequencing of Streptomyces sp. PKU-MA00045 revealed the biosynthetic gene cluster of fluostatins M-Q (1-5), which contained different genes and gene organizations compared to known fluostatin gene clusters, facilitating the investigation of the biosynthesis of the unique 6-5-6-6 ring skeleton in all fluostatins.

Bacillibactin and Bacillomycin Analogues with Cytotoxicities against Human Cancer Cell Lines from Marine Bacillus sp. PKU-MA00093 and PKU-MA00092.

Nonribosomal peptides from marine Bacillus strains have received considerable attention for their complex structures and potent bioactivities. In this study, we carried out PCR-based genome mining for potential nonribosomal peptides producers from our marine bacterial library. Twenty-one "positive" strains were screened out from 180 marine bacterial strains, and subsequent small-scale fermentation, HPLC and phylogenetic analysis afforded Bacillus sp. PKU-MA00092 and PKU-MA00093 as two candidates for large-scale fermentation and isolation. Ten nonribosomal peptides, including four bacillibactin analogues (1-4) and six bacillomycin D analogues (5-10) were discovered from Bacillus sp. PKU-MA00093 and PKU-MA00092, respectively. Compounds 1 and 2 are two new compounds and the ¹H NMR and 13C NMR data of compounds 7 and 9 is first provided. All compounds 1-10 were assayed for their cytotoxicities against human cancer cell lines HepG2 and MCF7, and the bacillomycin D analogues 7-10 showed moderate cytotoxicities with IC50 values from 2.9 ± 0.1 to 8.2 ± 0.2 µM. The discovery of 5-10 with different fatty acid moieties gave us the opportunity to reveal the structure-activity relationships of bacillomycin analogues against these human cancer cell lines. These results enrich the structural diversity and bioactivity properties of nonribosomal peptides from marine Bacillus strains.

In vivo metabolite profiles of isoimperatorin and phellopterin in rats analyzed using HPLC coupled with diode array detector and electrospray ionization ion trap time-of-flight mass spectrometry technique.

Isoimperatorin (IP) and phellopterin (PP) are two furocoumarins existing in Angelicae Dahuricae Radix. There is an isopentenyloxyl substituted at C-5 in IP, and an isopentenyloxyl and a methoxyl substituted at C-8 and C-5, respectively, in PP. To elucidate the in vivo metabolic characteristics of PP and IP, HPLC coupled with diode array detector and electrospray ionization ion trap time-of-flight mass spectrometry technique was used. In total, 111 metabolites, including 53 new ones, were identified from the urine and plasma samples of rats after oral administration of IP and PP, respectively. The metabolites were formed through eight reactions on IP and PP: oxidation, hydroxylation-hydrogenation, carboxylation on the isopentenyloxyl, O-dealkylation, hydroxylation on the furocoumarin nucleus, ring-opening reaction on the furan ring and reduction or ring-opening reaction on the lactone ring. Among these, hydroxylation on the furocoumarin nucleus was found for the first time for in vivo metabolites of PP and IP, and the ring-opening reaction on the furan ring or lactone ring was found for the first time for in vivo metabolites of isopentenyloxyl furocoumarins. The research gave us a new insight into the in vivo metabolic profiles of IP and PP, which could help us better understand their important roles as two active constituents of Angelicae Dahuricae Radix.

Dietary Total Prenylflavonoids from the Fruits of Psoralea corylifolia L. Prevents Age-Related Cognitive Deficits and Down-Regulates Alzheimer's Markers in SAMP8 Mice.

Alzheimer's disease (AD) is a serious threat for the aging society. In this study, we examined the preventive effect of the total prenylflavonoids (TPFB) prepared from the dried fruits of Psoralea corylifolia L., using an age-related AD mouse model SAMP8. We found that long-term dietary TPFB at 50 mg/kg·day significantly improved cognitive performance of the SAMP8 mice in Morris water maze tests, similar to 150 mg/kg·day of resveratrol, a popular neuro-protective compound. Furthermore, TPFB treatment showed significant improvements in various AD markers in SAMP8 brains, which were restored to near control levels of the normal mice, SAMR1. TPFB significantly reduced the level of amyloid ß-peptide 42 (Aß42), inhibited hyperphosphorylation of the microtubule-associated protein Tau, induced phosphorylation of Ser9 of the glycogen synthase kinase 3ß (GSK-3ß), and decreased the expression of the proinflammatory cytokines TNFα, IL-6, and IL-1ß. Finally, TPFB also markedly reduced the level of serum derivatives of reactive oxygen metabolites (d-ROMs), a biomarker of oxidative stress in vivo. These results showed that dietary TPFB could effectively prevent age-related cognitive deficits and AD-like neurobiochemical changes, and may have a potential role in the prevention of Alzheimer's disease.

Multi-Target Anti-Alzheimer Activities of Four Prenylated Compounds from Psoralea Fructus.

Alzheimer's disease (AD) is an age-related neurodegenerative disease that is mediated by multiple signaling pathways. In recent years, the components of Psoralea Fructus (PF) have demonstrated some anti-Alzheimer effects both in vitro and in vivo. To further reveal the active compounds of PF and their mechanisms regulating key targets of AD, in this study, we identified four prenylated compounds from the 70% ethanolic aqueous extract of PF, namely bavachin, bavachinin, bavachalcone, and isobavachalcone. Multi-target bioactivity analysis showed that these compounds could differentially inhibit neuroinflammation, oxidative damage, and key AD-related protein targets, such as amyloid ß-peptide 42, ß-secretase, glycogen synthase kinase 3ß, and acetylcholinesterase. These compounds may generate beneficial effects in AD prevention and treatment.

[Chemical constituents from Fukeqianjin formula].

Fukeqianjin formula, a traditional Chinese medicine compound, consists of eight Chinese medicinal materials including roots of Moghania macrophylla, roots of Rosa laevigata, aerial parts of Andrographis paniculata, caulis of Mahonia fortunei, roots of Zanthoxylum dissitum, roots of Angelica sinensis, caulis of Spatholobus suberectus, and roots of Codonopsis pilosula. The chemical constituents from Fukeqianjin formula were studied in this paper. The compounds were separated and purified by repeated column chromatographic methods including silica gel, Sephadex LH-20, macroporous adsorptive resin, and reverse phase high performance liquid chromatography. And their chemical structures were determined by spectral data analyses. Thirty-eight compounds were obtained and identified as Z-3-butylidenephthalide (1), Z-ligustilide (2), senkyunolide I (3), senkyunolide H (4), vanillin (5), 7-O-methylwogonin (6), wogonin (7), panicolin (8), 19-hydroxy-8(17),13-labdadien-15,16-olide (9), andrograpanin (3,14-dideoxyandrographolide; 10), andrographolide (11), 14-deoxy-11,12-didehydroandrographolide (12), isoandrographolide (13), andrographin (2'-O-methylskullcapflavone, 14), biochanin A (15), 5-hydroxy-7,8,2',5'-tetramethoxyflavone (16), formononetin (17), daidzein (18), genistein (19), benzoic acid (20), vanillic acid (21), trans-ferulic acid (22), salicylic acid (23), daidzin (24), genistein-7-O-ß-D-apiofuranosyl-(1→6)-O-ß-D-glucopyranoside (25), apigenin-7-O-ß-D-glucuronide (26), andrographidin C (27), apigenin-7-O-ß-D-(6"-methyl)glucuronide (28), neoandrographolide (29), genistin (30), andrographiside (31), 14-deoxy-11,12-didehydroandrographiside (32), lobetyolin (33), epicatechin (34), catechin (35), palmatine (36), berberine (37), and jatrorrhizine (38), respectively. From the results of an individual medicinal material studies, it can be judged that compounds 17, 19, 24 and 30 as flavonoids came from the roots of M. macrophylla, compounds 36-38 as alkaloids came from the caulis of M. fortunei, compounds 6-8, 14, 16, and 27 as flavonoids as well as 9-13, 29, 31, and 32 as diterpenes came from the aerial parts of A. paniculata, compound 5 as phenols came from the roots of Z. dissitum, compounds 1-4 as phthalides as well as compound 22 as phenylpropanoids came from the roots of A. sinensis, compound 33 as alkynes came from the roots of C. pilosula, compounds 15, 17-19 as flavonoids as well as compound 21 as phenolic acids came from the caulis of S. suberectus. While compounds 34 and 35 as flavanoids could come from both the caulis of S. suberectus and roots of R. laevigata. The chemical composition of traditional Chinese medicine compound can be tracked from the original sources. This work provides a demonstration for the material basis study of traditional Chinese medicine compound. Compounds 25, 26 and 28 have not so far been isolated and identified from the above-mentioned single herb.

Cloning, expression, and characterization of a four-component O-demethylase from human intestinal bacterium Eubacterium limosum ZL-II.

Eubacterium limosum ZL-II was described to convert secoisolariciresinol (SECO) to its demethylating product 4,4'-dihydroxyenterodiol (DHEND) under anoxic conditions. However, the reaction cascade remains unclear. Here, the O-demethylase being responsible for the conversion was identified and characterized. Nine genes encoding two methyltransferase-Is (MT-I), two corrinoid proteins (CP), two methyltransferase-IIs (MT-II), and three activating enzymes (AE) were screened, cloned, and expressed in Escherichia coli. Four of the nine predicted enzymes, including ELI_2003 (MT-I), ELI_2004 (CP), ELI_2005 (MT-II), and ELI_0370 (AE), were confirmed to constitute the O-demethylase in E. limosum ZL-II. The complete O-demethylase (combining the four components) reaction system was reconstructed in vitro. As expected, the demethylating products 3-demethyl-SECO and DHEND were both produced. During the reaction process, ELI_2003 (MT-I) initially catalyzed the transfer of methyl group from SECO to the corrinoid of ELI_2004 ([CoI]-CP), yielding demethylating products and [CH3-CoIII]-CP; then ELI_2005 (MT-II) mediated the transfer of methyl group from [CH3-CoIII]-CP to tetrahydrofolate, forming methyltetrahydrofolate and [CoI]-CP. Due to the low redox potential of [CoII]/[CoI], [CoI]-CP was oxidized to [CoII]-CP immediately in vitro, and ELI_0370 (AE) was responsible for catalyzing the reduction of [CoII]-CP to its active form [CoI]-CP. The active-site residues in ELI_2003, ELI_2005, and ELI_0370 were subsequently determined using molecular modeling combined with site-directed mutagenesis. To our knowledge, this is the first study on the identification and characterization of a four-component O-demethylase from E. limosum ZL-II, which will facilitate the development of method to artificial synthesis of related bioactive chemicals.

Multiple fingerprint and pattern recognition analysis on polysaccharides of four edible mushrooms.

Quality analysis of edible mushrooms based on polysaccharides is generally difficult due to their complicated structures and hard separation. Here, multiple fingerprint analysis of polysaccharides based on chromatographic and spectrometric techniques were developed, and then applied in comparative analysis of Auricularia heimuer (AH), Auricularia cornea (AC), Auricularia cornea 'Yu Muer' (ACY) and Tremella fuciformis (TF). Firstly, polysaccharides were obtained with the molecular weights between 1.783 × 106 and 6.774 × 106 Da. Then, complete hydrolysis by TFA and enzyme digestion by cellulase were employed and subsequently analyzed by HPLC-UV, GC-MS, HILIC-HPLC-ELSD and HILIC-HPLC-ESI--HCD-MS/MS, and ATR-FT-IR were used to characterize the functional groups of intact polysaccharides. By chemometric analysis, differential markers of d-xyl, l-fuc, l-arb, d-glc, disaccharide and hexasaccharide were selected, and AC and ACY were proved to be same species from the viewpoint of polysaccharides firstly. Furthermore, the structures of oligomers with DPs of 2-8 and →4)-ß-d-Glcp-(1→ unit with different contents were inferred by combinatory analysis of ESI--MS/MS, glycosidic linkage, monosaccharide compositions and functional groups. In conclusion, the combinatory method of multiple fingerprint and pattern recognition is powerful not only for structural elucidation of polysaccharides, but also for quality analysis and species differentiation of edible mushrooms from the perspective of biological polysaccharides.

An effective non-rigid registration approach for ultrasound image based on "demons" algorithm.

Medical image registration is an important component of computer-aided diagnosis system in diagnostics, therapy planning, and guidance of surgery. Because of its low signal/noise ratio (SNR), ultrasound (US) image registration is a difficult task. In this paper, a fully automatic non-rigid image registration algorithm based on demons algorithm is proposed for registration of ultrasound images. In the proposed method, an "inertia force" derived from the local motion trend of pixels in a Moore neighborhood system is produced and integrated into optical flow equation to estimate the demons force, which is helpful to handle the speckle noise and preserve the geometric continuity of US images. In the experiment, a series of US images and several similarity measure metrics are utilized for evaluating the performance. The experimental results demonstrate that the proposed method can register ultrasound images efficiently, robust to noise, quickly and automatically.