A fungal enzyme with the ability of aflatoxin B₁ conversion: purification and ESI-MS/MS identification

Armillariella tabescens, a Chinese edible and medicinal fungus, whose multienzyme exist ability of AFB₁-converting, and ADTZ (aflatoxin-detoxizyme) had previously purified from the A. tabescens multienzyme monitored by AFB₁ conversion_. However, the enzyme now confirmed an oxidase and renamed aflatoxin-oxidase (AFO). In this paper, AFO was purified by an economical and practical three-step procedure monitored by AFB₁ conversion. And ESI-MS/MS analysis was done for identification of AFO. The following database searching (Protein Blast on NCBI) results did not show any homologous oxidase protein, which implied that AFO was mostly a new oxidase differing from other reported aflatoxin-converting enzymes such as fungal laccase and horse radish peroxidase. HPTLC analysis of the purified AFO activity suggested that the enzyme reacted at the bisfuran ring of AFB₁ which was the key toxic structure. Therefore, all these investigations implied a new choice for biodegradation of aflatoxin in foods and feeds with the practical application of AFO.     

Synthesis and in vitro antitubercular evaluation of novel sansanmycin derivatives

Tuberculosis (TB) is a major health problem worldwide. A series of novel sansanmycin derivatives were designed, semi-synthesized and evaluated for their activity against drug-susceptible Mycobacterium tuberculosis strain H(37)Rv with sansanmycin A (SSA) as the lead. Among these analogs tested, compound 1d possessing an isopropyl group at the amino terminal afforded an increased antimycobacterial activity with a MIC value of 8 μg/mL in comparison with SSA. Importantly, it was active for rifampicin- and isoniazid-resistant M. tuberculosis strain isolated from patients in China. These promising results offer an opportunity for further exploration of this novel class of analogs as antitubercular agents.     

Homo- and hetero-dimers of inactive organophosphorous group binding at dual sites of AChE

Homo- and hetero-dimers of inactive organophosphorous group(s) dramatically enhanced the acetylcholinesterase (AChE; EC 3.1.1.7) inhibiting potency, with the highest potency observed at a tether length of 6 methylene groups (6d) for the homodimers, and 7 methylene groups (8e) for the heterodimers. The docking model of Drosophila melanogaster AChE suggested that 6d and 8e bound at the catalytic and peripheral sites of AChE, in which two organophosphorous groups of 6d individually oriented towards TRP83 of catalytic sites and TRP321 of peripheral sites, and phthalicimide group of 8e was appropriately arranged for a π-π interaction with the phenyl ring of TYR330, furthermore, the organophosphorous group introduced hydrophobic interaction with TRP83. The compounds prepared in this work demonstrated high insecticidal activity to Lipaphis erysimi and Tetranychus cinnbarinus at the concentration 300mg/L.     

Methyl-monofluorination of ibuprofen selectively increases its inhibitory activity toward cyclooxygenase-1 leading to enhanced analgesic activity and reduced gastric damage in vivo

Newly developed monofluoromethylation reaction provided access to various bioactive molecules with an interesting monofluoromethyl unit. An iridium-catalyzed asymmetric version was employed for large-scale methyl-monofluorination of widely used nonsteroidal anti-inflammatory drug ibuprofen (the active S isoform). The methyl-monofluorinated ibuprofen was found to selectively inhibit cyclooxygenase-1 over cyclooxygenase-2 and surprisingly, the compound, with almost equal pharmacokinetic profile, was shown to increase analgesic activity and diminish gastric damage in animal models comparing to the parent drug ibuprofen. Therefore, methyl-monofluorination could be a useful strategy for improving efficacy and safety profile of drugs from the ‘profen’ family.     

Stem cells: keeping BMP signaling local

In stem cell niches, the spatial extent of growth factor signaling needs to be tightly controlled. A new study on the Drosophila testicular germline stem cell niche has revealed that BMP signaling is locally activated through linkage to adherens junctions.     

The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.     

Structure and dynamics of the periphytic algae of Jinyang Lake in Shanxi Province, North China

The structure and dynamics of periphytic algae in Jinyang Lake, the largest man-made lake in Taiyuan, Shanxi, have been studied by examining the periphytic algae samples collected from four sampling stations, during March 2006 to February 2007. In total, 227 species of periphytic algae (including varieties), belonging to three divisions, 27 families, 62 genera, have been identified. Diatoms were the dominant periphytic algae group. Taken the Shannon–Weaver, Margalef and Simpson diversity index together, it showed obvious temporal and spatial dynamics among different seasons and different sampling stations. The highest periphytic community structure evenness appeared at sampling station I in spring, summer and autumn, while at sampling station III in winter. The average biomass of periphytic algae varied from seasons. Our data showed that major factors affecting the periphytic algae in Jinyang Lake was water temperature, nutrient levels as well as human activities. In addition, the main effect caused by thermal power plant has been discussed.     

The EAG response and behavior of the Saperda populnea L. to volatiles from poplar branches

In order to investigate the effect of organic volatiles from poplar species on the host plants orientation of Saperda populnea, the essential oil in the 2–3 years old branches from the sapling or mature trees of Populus simonii Carr. and P. simonii Carr. × P. nigra L. were extracted using the steam distillation method. The chemical composition and relative content in essential oil from those branches was analyzed by GC–MS. The main components contained in those volatiles from the four kinds of branches are mainly aromatic compounds such as 1,2-cyclohexanedione, 2-cyclohexene-1-one, p-xylene and 1,2,3-trimethylbenzene and so on. The relative content of aromatic compounds contained in branches from saplings was higher than that contained in branches from old tress. EAG response and behavioral reaction of S. populnea L. to those four kinds of distillated essential oil were tested. The results shown that male and female adults of S. populnea L. shown significant choice behavior and strong olfactory response to those essential oil distillated from branches of P. simonii Carr. and P. simonii Carr. × P. nigra L.. The EAG bioassay of S. populnea L. to 10 kinds of monomers compounds which had relative higher contents was tested. The results shown that the EAG response of female adults of S. populnea L. to 1 mol L^?1 p-xylene was intensest and reached 1.027 mV, the strength of their EAG response to 0.1 mol L^?1 phenol took the second place. The EAG response of male adult of S. populnea L. to 1 mol L^?1 p-xylene was strongest and reached to 0.824 mV, the strength of their EAG response to 1 mol L^?1 salicylaldehyde took the second place. In the choice behavior test of S. populnea L. adult to monomeric compound carried out in ‘Y’ type olfactometer have found that female and male adult of S. populnea L. all appeared obvious positive taxis to 0.1 mol L^?1 p-xylene. The selection rate of female and male adults ware (76.7 ± 4.1)% and (71.7 ± 2.6)%, respectively. The selective reaction to 0.1 mol L^?1 1,2-cyclohexanedione and 2-cyclohexene-1-one were not obviously than that to 0.1 mol L^?1 p-xylene. The male and female adult of S. populnea L. appeared repelling behavior to 0.1 mol L^?1 salicylaldehyde.     

Advanced glycation end product recognition by the receptor for AGEs

Nonenzymatic protein glycation results in the formation of advanced glycation end products (AGEs) that are implicated in the pathology of diabetes, chronic inflammation, Alzheimer's disease, and cancer. AGEs mediate their effects primarily through a receptor-dependent pathway in which AGEs bind to a specific cell surface associated receptor, the Receptor for AGEs (RAGE). N(?)-carboxy-methyl-lysine (CML) and N(?)-carboxy-ethyl-lysine (CEL), constitute two of the major AGE structures found in tissue and blood plasma, and are physiological ligands of RAGE. The solution structure of a CEL-containing peptide-RAGE V domain complex reveals that the carboxyethyl moiety fits inside a positively charged cavity of the V domain. Peptide backbone atoms make specific contacts with the V domain. The geometry of the bound CEL peptide is compatible with many CML (CEL)-modified sites found in plasma proteins. The structure explains how such patterned ligands as CML (CEL)-proteins bind to RAGE and contribute to RAGE signaling.