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Solvent-Free Synthesis of -Amino Ketones from -Hydroxyl Ketones via A Novel Tandem Reaction Sequence Based on Heyns Rearrangement
No full textHeyns rearrangement have been famous for carbohydrate chemists for several decades. However, this reaction was underrated as a useful method for synthetic chemists due to preparative shortcomings. Herein we developed an efficient method for the synthesis of pharmaceutically important -amino ketones from readily available -hydroxy ketones and secondary amines through a tandem reaction sequence based on Heyns rearrangement. The reaction smoothly proceeded by using catalytic PTSA as catalyst without solvent. Primary and secondary -hydroxy ketones were readily used and regioselectively afforded the correspondingly -amino ketones with moderate yield
Eight new species of Polystichum (subg. Haplopolystichum; Dryopteridaceae) from limestone caves in Guangdong and Yunnan, China, with reference to species diversity in the karst terrains at high elevations in subtropical areas
No full textEight new fern species of Polystichum subg. Haplopolystichum (Dryopteridaceae) are described and illustrated from Guangdong and Yunnan provinces, southern and southwestern China, respectively. These eight species include P. deltatum, P. gejiuense, P. malipoense, P. oblongipinnarum, P. pingbianense, P. rectum, and P. superum from Yunnan, and P. hanmengqii from Guangdong. Four of the eight species are described from high elevations (around 2000 m) demonstrating that the limestone areas at high elevations in subtropical areas are species-rich and deserve special conservation attention. All eight species are so far known only from single caves; they are all classified as Critically Endangered (CR) following IUCN Red List criteria
Instability diagnosis and syntrophic acetate oxidation during thermophilic digestion of vegetable waste
No full textEffective process monitoring and instability diagnosis are important for stable anaerobic digestion (AD) of vegetable waste (VW). In order to evaluate the performance of thermophilic digestion of VW, to make early diagnosis for instability after organic overload, and to reveal the dynamics of microbial community under different running states, thermophilic AD of VW was carried out under improved organic loading rates (OLR) of 0.5-2.5 g volatile solid (VS)/(L . d) in this study. Gaseous parameters including volumetric methane production rate (VMPR), CH4, CO2, and H-2 concentrations, and liquid parameters including pH, oxidation reduction potential, volatile fatty acid (VFA), and total alkalinity (TA), bicarbonate alkalinity (BA), intermediate alkalinity (IA), and ammonia, were monitored. The coupling parameters, such as the CH4/CO2, VFA/BA, and BA/TA ratios were also used to evaluate stability. The dynamics of syntrophic acetate-oxidizing bacteria (SAOB), acetoclastic methanogens (AM), and hydrogenotrophic methanogens (HM) were analyzed by high-throughput sequencing. The main methanogenic bacteria were HM (Methanothermobacter) during the start-up period of OLR 0.5 gVS/(L . d), while they were AM (Methanosarcina) during the stable period of OLR of 1.0 gVS/(L . d). The VMPR of stable period was about 0.29 L/(L . d) with total VFA concentration below 100 mg/L, CH4/CO2 > 1.3, and BA/TA>0.9. The first instability due to the accumulation of VFA and self-recovery due to syntrophic acetate oxidation occurred at an OLR of 1.5 g VS/(L . d). The syntrophic acetate-oxidizing bacteria probably belong to genus S1 (family Thermotogaceae). The digestion failed at an OLR of 2.0 g VS/(L . d). H-2 was only detected during collapsed period instead of instable period. The total ammonia nitrogen loss and bicarbonate alkalinity (BA) reduction were the primary causes for the instability of AD of VW without effluent recirculation. Compared with single parameters, the CH4/CO2 and BA/total alkalinity (TA) ratios are recommended as early warning indicators for engineering applications of thermophilic AD of VW. (C) 2018 Elsevier Ltd. All rights reserved
Notes on the distribution of Venturiella perrottetii (Bryophyta: Erpodiaceae), with new records reported from Myanmar and Thailand
No full textVenturiella perrottetii (Erpodiaceae) is newly reported from Myanmar and Thailand. Taxonomic history of the species in Thailand and the species distribution in China and Thailand are discussed. Photographs of key morphological features are provided for the first time
Optimization of growth and production parameters of walnut (Juglans regia) saplings with response surface methodology
No full textStraw mulching is an effective conservation tillage tool that utilizes waste resources and reduces environmental pollution. To determine the optimal levels of quality, placement and quantity of straw mulching, we performed a field experiment that used the Box-Behnken design combined with response surface methodology. The treatments designed for walnut saplings (Juglans regia) considered three independent variables: quality, placement, and quantity of straw mulching. Tree height of walnut saplings (THW) and net photosynthesis rate (NPR) were used as the response variables in a full, quadratic polynomial model. Analysis of variance (ANOVA) results showed that the selected models were significant (P = 0.9225). The optimum conditions for the THW and NPR responses were determined to be a straw mulching quality which mixed rice and rapeseed straws, a straw mulching placement which covered the entire soil surface of experimental plots, and a straw mulching quantity applied as 3 kg/m(2) (i.e., the low level). This optimized scheme of straw mulching combinations offers an alternate choice for optimizing the growth and potential yield of walnut saplings, but practical field experiments should also be carried out to obtain more site-specific results
Transcriptomics reveals the molecular processes of light-induced rapid darkening of the non-obligate cave dweller Oreolalax rhodostigmatus (Megophryidae, Anura) and their genetic basis of pigmentation strategy
No full textBackground: Vertebrates use different pigmentation strategies to adapt to various environments. A large amount of research has been done on disclosing the mechanisms of pigmentation strategies in vertebrates either under light, or, living in constant darkness. However, less attention has been paid to non-obligate, darkness dwellers. Red-spotted toothed toads Oreolalax rhodostigmatus (Megophryidae; Anura) from the karst mountainous region of southwestern China are non-obligate cave dwellers. Most tadpoles of the species possess transparent skin as they inhabit the dark karst caves. But remarkably, the transparent tadpoles can darken just within 15 h once exposed to light. Obviously, it is very significant to reveal molecular mechanisms of the unexpected rapid-darkening phenomenon. Results: We compared the transcriptomes of O. rhodostigmatus tadpoles with different durations of light exposure to investigate the cellular processes and potential regulation signals for their light-induced rapid darkening. Genes involved in melanogenesis (i.e. TYR, TYRP1 and DCT) and melanocyte proliferation, as well as their transcriptional factor (MITF), showed light-induced transcription, suggesting a dominating role of morphological color change (MCC) in this process. Transcription of genes related to growth factor, MAPK and PI3K-Akt pathways increased with time of light exposure, suggesting that light could induce significant growth signal, which might facilitate the rapid skin darkening. Most importantly, an in-frame deletion of four residues was identified in O. rhodostigmatus melanocortin-1 receptor (MC1R), a critical receptor in MCC. This deletion results in a more negatively charged ligand pocket with three stereo-tandem aspartate residues. Such structural changes likely decrease the constitutive activity of MC1R, but increase its ligands-dependent activity, thus coordinating pigment regression and rapid melanogenesis in the dark and light, respectively. Conclusion: Our study suggested that rapid MCC was responsible for the light-induced rapid darkening of O. rhodostigmatus tadpoles. Genetic mutations of MC1R in them could explain how these non-obligate cave dwellers coordinate pigment regression and robust melanogenesis in darkness and light, respectively. To our knowledge, this is the first study that reports the association between pigmentation phenotype adaptation and MC1R mutations in amphibians and/or in non-obligate cave dwellers
Migratory Whooper Swans Cygnus cygnus Transmit H5N1 Virus between China and Mongolia: Combination Evidence from Satellite Tracking and Phylogenetics Analysis
No full textIn late 2014, a highly pathogenic avian influenza (hereafter HPAI) H5N1 outbreak infected whooper swans Cygnus cygnus wintering at the Sanmenxia Reservoir area, China, and raised concerns about migratory linkages between wintering and breeding grounds of whooper swans. In this study, 61 swans were satellite tracked from 2013 to 2016 to determine the spatial association of their migration routes and H5N1 outbreaks, and 3596 fecal samples were collected along the migration routes for virology testing. Swans departed the wintering grounds and migrated along the Yellow River, and flew over the Yin Mountains in China. The Brownian bridge movement model showed there was a high degree of spatiotemporal overlap between the core use area along the spring migration pathway and historical H5N1 events in China and Mongolia from 2005 to 2015. The H5N1 strain was isolated and phylogenetic analyses confirmed that the HA gene sequence generated is genetically similar to that of the epidemic strain at a previous wintering site (the Sanmenxia Reservoir area) along its flyway. Our results identified a previously unknown migratory link of whooper swans in central China with Mongolia and confirmed that the swans could carry the HPAI H5N1 virus during migration, resulting in long-distance transmission
A group of nuclear factor Y transcription factors are sub-functionalized during endosperm development in monocots
No full textNuclear factor Y (NF-Y) is a heterotrimeric transcription factor that consists of three subunits, NF-YA, NF-YB, and NF-YC. Gene functions of NF-Ys during endosperm development are not well understood. In this study, we identified eight rice NF-Y-encoding genes, namely OsNF-YA8, OsNF-YB1,9, and OsNF-YC8,9,10,11,12, that are predominantly expressed in the endosperm. Interestingly, the close homologs of these OsNF-Ys are present only in monocot species and are also preferentially expressed in the endosperm, suggesting that they have roles in the regulation of endosperm development. A systemic analysis of interactions between rice endosperm-preferential NF-Ys in yeast revealed that OsNF-YBs and OsNF-YCs could interact with each other. We also found that the endosperm-preferential OsNFYBs and OsNF-YCs could interact with some ethylene response factors (ERFs) of rice. Unlike OsNF-YC8,9,10, the members of OsNF-YB1,9 or OsNF-YC 11,12 showed no transcriptional activation when present alone. However, they displayed functional activity while in dimer form. In addition, OsNF-YB1-knockout lines showed significant changes in seed morphology, further confirming its role in endosperm development. Our findings provide evidence that a group of phylogenetically conserved NF-Ys is probably differentiated in monocots to regulate endosperm development
The right thalamus may play an important role in anesthesia-awakening regulation in frogs
No full textBackground. Previous studies have shown that the mammalian thalamus is a key structure for anesthesia-induced unconsciousness and anesthesia-awakening regulation. However, both the dynamic characteristics and probable lateralization of thalamic functioning during anesthesia-awakening regulation are not fully understood, and little is known of the evolutionary basis of the role of the thalamus in anesthesia-awakening regulation. Methods. An amphibian species, the South African clawed frog (Xenopus laevis) was used in the present study. The frogs were immersed in triciane methanesulfonate (MS-222) for general anesthesia. Electroencephalogram (EEG) signals were recorded continuously from both sides of the telencephalon, diencephalon (thalamus) and mesencephalon during the pre-anesthesia stage, administration stage, recovery stage and post-anesthesia stage. EEG data was analyzed including calculation of approximate entropy (ApEn) and permutation entropy (PE). Results. Both ApEn and PE values differed significantly between anesthesia stages, with the highest values occurring during the awakening period and the lowest values during the anesthesia period. There was a significant correlation between the stage durations and ApEn or PE values during anesthesia-awakening cycle primarily for the right diencephalon (right thalamus). ApEn and PE values for females were significantly higher than those for males. Discussion. ApEn and PE measurements are suitable for estimating depth of anesthesia and complexity of amphibian brain activity. The right thalamus appears physiologically positioned to play an important role in anesthesia-awakening regulation in frogs indicating an early evolutionary origin of the role of the thalamus in arousal and consciousness in land vertebrates. Sex differences exist in the neural regulation of general anesthesia in frogs
Enantioselective Copper-Catalyzed Methylboration of Alkenes
No full textAn enantioselective Cu-catalyzed borylative cross coupling reaction of alkenes, bis(pinacolato)diboron (B-2(pin)(2)), and methyl iodide is reported. Alkenes including styrenes, beta-substituted styrenes, and challenging aliphatic olefins were smoothly transferred to the desired methylboration products with excellent diastereoselectivities (dr up to >99:1) and enantioselectivities (er up to 99:1). The utility of this process was demonstrated by the synthesis of naproxen and formal synthesis of two natural products