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https://www.readbyqxmd.com/read/28651087/effects-of-terrestrial-and-marine-organic-matters-on-deposition-of-dechlorane-plus-dp-in-marine-sediments-from-the-southern-yellow-sea-china-evidence-from-multiple-biomarkers
#1
Guoguang Wang, Jialin Peng, Ting Hao, Lijuan Feng, Qiaoling Liu, Xianguo Li
As an emerging halogenated organic contaminant, Dechlorane Plus (DP) was scarcely reported in marine environments, especially in China. In this work, 35 surface sediments and a sediment core were collected across the Southern Yellow Sea (SYS) to comprehensively explore the spatio-temporal distribution and possible migration pathway of DP. DP concentrations ranged from 14.3 to 245.5 pg/g dry weight in the surface sediments, displaying a seaward increasing trend with the high levels in the central mud zone. This spatial distribution pattern was ascribed to that fine particles with the elevated DP levels were preferentially transported to the central mud zone under hydrodynamic forcing and/or via long-range atmospheric transportation and deposition...
June 23, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28650732/air-hand-wipe-and-surface-wipe-sampling-for-bisphenol-a-bpa-among-workers-in-industries-that-manufacture-and-use-bpa-in-the-united-states
#2
Cynthia J Hines, Matthew V Jackson, Annette L Christianson, John C Clark, James E Arnold, Jack R Pretty, James A Deddens
For decades, bisphenol A (BPA) has been used in making polycarbonate, epoxy, and phenolic resins and certain investment casting waxes, yet published exposure data are lacking for U.S. manufacturing workers. In 2013-2014, BPA air and hand exposures were quantified for 78 workers at six U.S. companies making BPA or BPA-based products. Exposure measures included an inhalable-fraction personal air sample on each of two consecutive work days (n = 146), pre- and end-shift hand wipe samples on the second day (n = 74 each), and surface wipe samples (n = 88)...
June 26, 2017: Journal of Occupational and Environmental Hygiene
https://www.readbyqxmd.com/read/28650525/thermal-synthesis-of-perchlorinated-oligosilanes-a-fresh-look-at-an-old-reaction
#3
Max C Holthausen, Felix Neumeyer, Julia I Schweizer, Lioba Meyer, Alexander G Sturm, Andor Nadj, Norbert Auner
A combined experimental and theoretical study of the high-temperature reaction of SiCl4 and elemental silicon is presented. The nature and reactivity of the product formed upon rapid cooling of the gaseous reaction mixture is investigated by comparison with defined model compounds, i.e. cyclo-Si5Cl10, n-Si5Cl12 and n-Si4Cl10. A DFT assessment provides mechanistic insight into the oligosilane formation. Experimental 29Si NMR investigations, supported by quantum-chemical 29Si NMR calculations, consistently show that the reaction product is composed of discrete molecular perchlorinated oligosilanes...
June 26, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28650492/exploiting-the-biosynthetic-machinery-of-streptomyces-pilosus-to-engineer-a-water-soluble-zirconium-iv-chelator
#4
Tomas Richardson-Sanchez, William Tieu, Michael P Gotsbacher, Thomas J Telfer, Rachel Codd
The water solubility of a natural product-inspired octadentate hydroxamic acid chelator designed to coordinate Zr(iv)-89 has been improved by using a combined microbiological-chemical approach to engineer four ether oxygen atoms into the main-chain region of a methylene-containing analogue. First, an analogue of the trimeric hydroxamic acid desferrioxamine B (DFOB) that contained three main-chain ether oxygen atoms (DFOB-O3) was generated from cultures of the native DFOB-producer Streptomyces pilosus supplemented with oxybis(ethanamine) (OBEA), which competed against the native 1,5-diaminopentane (DP) substrate during DFOB assembly...
June 26, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28650175/bioactive-peptide-natural-products-as-lead-structures-for-medicinal-use
#5
Tam Dang, Roderich D Süssmuth
The need for new drugs for the treatment of various diseases is enormous. From the previous century until the present, numerous peptide and peptide-derived natural products have been isolated from bacteria and fungi. Hence, microorganisms play a pivotal role as sources for novel drugs with an emphasis on anti-infective agents. Various disciplines from biology, chemistry, and medicine are involved in early stages of the search for peptide natural products including taxonomy, microbiology, bioanalytics, bioinformatics, and medicinal chemistry...
June 26, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28650156/discovery-of-a-glutamine-kinase-required-for-the-biosynthesis-of-the-o-methyl-phosphoramidate-modifications-found-in-the-capsular-polysaccharides-of-campylobacter-jejuni
#6
Zane W Taylor, Haley A Brown, Tamari Narindoshvili, Cory Q Wenzel, Christine Szymanski, Hazel M Holden, Frank M Raushel
Bacterial capsular polysaccharides (CPS) are complex carbohydrate structures that play a role in the overall fitness of the organism. Campylobacter jejuni, known for being a major cause of bacterial gastroenteritis worldwide, produces a CPS with a unique O-methyl phosphoramidate (MeOPN) modification on specific sugar residues. The formation of P-N bonds in nature is relatively rare and the pathway for the assembly of the phosphoramidate moiety in the CPS of C. jejuni is unknown. In this investigation we discovered that the initial transformation in the biosynthetic pathway for the MeOPN modification of the CPS involves the direct phosphorylation of the amide nitrogen of L-glutamine with ATP by the catalytic activity of Cj1418...
June 26, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28650100/tautomerization-and-dissociation-of-molecular-peptide-radical-cations
#7
REVIEW
Xiaoyan Mu, Tao Song, Chi-Kit Siu, Ivan K Chu
Radical-mediated dissociations of peptide radical cations have intriguing unimolecular gas phase chemistry, with cleavages of almost every bond of the peptide backbone and amino acid side chains in a competitive and apparently "stochastic" manner. Challenges of unraveling mechanistic details are related to complex tautomerizations prior to dissociations. Recent conjunctions of experimental and theoretical investigations have revealed the existence of non-interconvertible isobaric tautomers with a variety of radical-site-specific initial structures, generated from dissociative electron transfer of ternary metal-ligand-peptide complexes...
June 26, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28650071/in-vivo-synergistic-activity-of-a-cazyme-cassette-from-acidothermus-cellulolyticus-significantly-improves-the-cellulolytic-activity-of-the-c-bescii-exoproteome
#8
Sun-Ki Kim, Daehwan Chung, Michael E Himmel, Yannick J Bomble, Janet Westpheling
The use of microbial cells to convert plant biomass directly to fuels and chemicals is referred to as consolidated bioprocessing (CBP). Members of the bacterial genus, Caldicellulosiruptor (Gram-positive, anaerobic hyperthermophiles) are capable of deconstructing plant biomass without enzymatic or chemical pretreatment. This is accomplished by the production and secretion of free, multi-domain enzymes that outperform commercial enzyme cocktails on some substrates. Here, we show that the exoproteome of C. bescii may be enhanced by the heterologous expression of enzymes from Acidothermus cellulolyticus that act synergistically to improve sugar release from complex substrates; as well as improve cell growth...
June 26, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28650068/rational-engineering-of-p-hydroxybenzoate-hydroxylase-to-enable-efficient-gallic-acid-synthesis-via-a-novel-artificial-biosynthetic-pathway
#9
Zhenya Chen, Xiaolin Shen, Jian Wang, Jia Wang, Qipeng Yuan, Yajun Yan
Gallic acid (GA) is a naturally occurring phytochemical that has strong antioxidant and antibacterial activities. It is also used as a potential platform chemical for the synthesis of diverse high-value compounds. Hydrolytic degradation of tannins by acids, bases or microorganisms serves as a major way for GA production, which however, might cause environmental pollution and low yield and efficiency. Here, we report a novel approach for efficient microbial production of GA. First, structure-based rational engineering of PobA, a p-hydroxybenzoate hydroxylase from Pseudomonas aeruginosa, generated a new mutant, Y385F/T294A PobA, which displayed much higher activity towards 3,4-dihydroxybenzoic acid (3,4-DHBA) than the wild type and any other reported mutants...
June 26, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28650032/antibiotics-from-gram-negative-bacteria-a-comprehensive-overview-and-selected-biosynthetic-highlights
#10
REVIEW
J Masschelein, M Jenner, G L Challis
Covering: up to 2017The overwhelming majority of antibiotics in clinical use originate from Gram-positive Actinobacteria. In recent years, however, Gram-negative bacteria have become increasingly recognised as a rich yet underexplored source of novel antimicrobials, with the potential to combat the looming health threat posed by antibiotic resistance. In this article, we have compiled a comprehensive list of natural products with antimicrobial activity from Gram-negative bacteria, including information on their biosynthetic origin(s) and molecular target(s), where known...
June 26, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28649989/an-l-threonine-transaldolase-is-required-for-l-threo-%C3%AE-hydroxy-%C3%AE-amino-acid-assembly-during-obafluorin-biosynthesis
#11
Thomas A Scott, Daniel Heine, Zhiwei Qin, Barrie Wilkinson
β-Lactone natural products occur infrequently in nature but possess a variety of potent and valuable biological activities. They are commonly derived from β-hydroxy-α-amino acids, which are themselves valuable chiral building blocks for chemical synthesis and precursors to numerous important medicines. However, despite a number of excellent synthetic methods for their asymmetric synthesis, few effective enzymatic tools exist for their preparation. Here we report cloning of the biosynthetic gene cluster for the β-lactone antibiotic obafluorin and delineate its biosynthetic pathway...
June 26, 2017: Nature Communications
https://www.readbyqxmd.com/read/28649802/punctal-occlusion-for-dry-eye-syndrome
#12
REVIEW
Ann-Margret Ervin, Andrew Law, Andrew D Pucker
BACKGROUND: Dry eye syndrome is a disorder of the tear film that is associated with symptoms of ocular discomfort. Punctal occlusion is a mechanical treatment that blocks the tear drainage system in order to aid in the preservation of natural tears on the ocular surface. OBJECTIVES: To assess the effects of punctal plugs versus no punctal plugs, different types of punctal plugs, and other interventions for managing dry eye. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 11), MEDLINE Ovid (1946 to 8 December 2016), Embase...
June 26, 2017: Cochrane Database of Systematic Reviews
https://www.readbyqxmd.com/read/28649801/vaccinia-virus-detection-in-dairy-products-made-with-milk-from-experimentally-infected-cows
#13
T M L de Oliveira, M I M C Guedes, I S Rehfeld, A C D Matos, A V Rivetti Júnior, A F da Cunha, M M O P Cerqueira, J S Abrahão, Z I P Lobato
Vaccinia virus (VACV) is the agent of bovine vaccinia (BV), an emerging zoonosis that causes exanthematic lesions on the teats of dairy cows and on the hands of milkers. The virus has been detected in the milk of naturally infected cows. The objective of this study was to investigate and quantify VACV DNA as well as the presence of infectious virus particles in samples of cheese curd, cheese whey and pasteurized milk produced using milk from cows experimentally inoculated with VACV-GP2, a Brazilian isolate of VACV (VACV-BR)...
June 26, 2017: Transboundary and Emerging Diseases
https://www.readbyqxmd.com/read/28649763/transformations-of-some-sesquiterpene-lactones-by-filamentous-fungi-cytotoxic-evaluations
#14
Arturo Cano-Flores, Guillermo Delgado
Biotransformation is an economically and ecologically viable technology which has been used to modify the structures of many classes of biologically active products. Some fungi may be useful for the biotransformation of sesquiterpene lactones (SLs), leading to unusual structural changes that modify their biological activities, and other transformations mimic their biosynthetic pathways, generating evidences for the proposed biogenesis. Eight filamentous fungi were screened for their ability to transform different SLs (1-9), and microbial reactions yielded compounds 11 -- 18, which in turn have been isolated as natural products, thus mimicking their biosynthesis...
June 26, 2017: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28649680/enzymatic-competition-and-cooperation-branch-the-caerulomycin-biosynthetic-pathway-toward-different-2-2-bipyridine-members
#15
Ming Chen, Yipeng Zhang, Yanan Du, Qunfei Zhao, Qinglin Zhang, Jiequn Wu, Wen Liu
In this study, we characterized CaeB6 as a selective hydroxylase and CaeG1 as an O-methyltransferase in the biosynthesis of the 2,2'-bipyridine natural products caerulomycins (CAEs). The C3-hydroxylation activity of CaeB6 competes with the C4-O-methylation activity of CaeG1 and thereby branches the CAE pathway from a common C4-O-demethylated 2,2'-bipyridine intermediate. CaeG1-catalyzed C4-O-methylation leads to a main route that produces the major product CAE-A in Actinoalloteichus cyanogriseus NRRL B-2194...
June 26, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28649508/isolation-of-shewanella-putrefaciens-in-an-elderly-man-with-subacute-intestinal-obstruction-appendicitis
#16
Arif Maqsood Ali, Muhammad Noorulamin, Shazia Arif
Shewanella is Gram-negative motile bacillus, non fermentative and facultative anaerobe. Its natural habitat is all forms of water and soil, but has also been isolated from fish, dairy products, oils, and carcasses. Often found with microflora of the marine environment. Bacterial infections with Shewanella spp. are rare. The exposure to the marine environment, sea and diary food are considered as a risk factor for Shewanella spp. infection. Clinical infections seen are otitis, soft tissue infection, bacteremia, ear infection, eye infection, infective arthritis, osteomyelitis, infective endocarditis and peritonitis...
2017: IDCases
https://www.readbyqxmd.com/read/28649409/bacillus-subtilis-utilizes-the-dna-damage-response-to-manage-multicellular-development
#17
Kevin Gozzi, Carly Ching, Srinand Paruthiyil, Yinjuan Zhao, Veronica Godoy-Carter, Yunrong Chai
Bacteria switch between free-living and a multicellular state, known as biofilms, in response to cellular and environmental cues. It is important to understand how these cues influence biofilm development as biofilms are not only ubiquitous in nature but are also causative agents of infectious diseases. It is often believed that any stress triggers biofilm formation as a means of bacterial protection. In this study, we propose a new mechanism for how cellular and environmental DNA damage may influence biofilm formation...
2017: NPJ Biofilms and Microbiomes
https://www.readbyqxmd.com/read/28649402/evolutionary-adaptations-of-biofilms-infecting-cystic-fibrosis-lungs-promote-mechanical-toughness-by-adjusting-polysaccharide-production
#18
Kristin Kovach, Megan Davis-Fields, Yasuhiko Irie, Kanishk Jain, Shashvat Doorwar, Katherine Vuong, Numa Dhamani, Kishore Mohanty, Ahmed Touhami, Vernita D Gordon
Biofilms are communities of microbes embedded in a matrix of extracellular polymeric substances, largely polysaccharides. Multiple types of extracellular polymeric substances can be produced by a single bacterial strain. The distinct polymer components of biofilms are known to provide chemical protection, but little is known about how distinct extracellular polysaccharides may also protect biofilms against mechanical stresses such as shear or phagocytic engulfment. Decades-long infections of Pseudomonas. aeruginosa biofilms in the lungs of cystic fibrosis patients are natural models for studies of biofilm fitness under pressure from antibiotics and the immune system...
2017: NPJ Biofilms and Microbiomes
https://www.readbyqxmd.com/read/28649374/screening-and-identification-of-novel-biologically-active-natural-compounds
#19
REVIEW
David Newman
With the advent of very rapid and cheap genome analyses and the linkage of these plus microbial metabolomics to potential compound structures came the realization that there was an immense sea of novel agents to be mined and tested. In addition, it is now recognized that there is significant microbial involvement in many natural products isolated from "nominally non-microbial sources". This short review covers the current screening methods that have evolved and one might even be tempted to say "devolved" in light of the realization that target-based screens had problems when the products entered clinical testing, with off-target effects being the major ones...
2017: F1000Research
https://www.readbyqxmd.com/read/28649279/a-simple-method-to-control-glycolytic-flux-for-the-design-of-an-optimal-cell-factory
#20
Jae Hyung Lim, Gyoo Yeol Jung
BACKGROUND: A microbial cell factory with high yield and productivity are prerequisites for an economically feasible bio-based chemical industry. However, cell factories that show a kinetic imbalance between glycolysis and product formation pathways are not optimal. Glycolysis activity is highly robust for survival in nature, but is not optimized for chemical production. RESULTS: Here, we propose a novel approach to balance glycolytic activity with the product formation capacity by precisely controlling expression level of ptsG (encoded glucose transporter) through UTR engineering...
2017: Biotechnology for Biofuels
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