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A global phylogeny of the fern genus Tectaria (Tectariaceae: Polypodiales) based on plastid and nuclear markers identifies major evolutionary lineages and suggests repeated evolution of free venation from anastomosing venation
No full textTectaria (Tectariaceae) is one of the most confusing fern genera in terms of its circumscription and phylogeny. Since its original description, a number of genera had been moved into or related with this genus, while others had been segregated from it. Tectaria is also among the largest fern genera, comprising 150210 mostly tropical species. Previous molecular studies have been far from comprehensive (sampling no more than 76 accessions from 52 species), limited in geographic scope (mainly restricted to Asia), and based exclusively on plastid markers. In the present study, DNA sequences of eight plastid and one nuclear marker of 360 accessions representing ca. 130 species of Tectaria, ca. 36 species of six non-Tectaria genera in Tectariaceae, 12 species of Davalliaceae, Oleandraceae, and Polypodiaceae, and 13 species of Lomariopsidaceae were used to infer a phylogeny with maximum likelihood, Bayesian inference, and maximum parsimony approaches. Our major results include: (1) the most recently proposed circumscription of Tectaria is strongly supported as monophyletic; (2) the genera Lenda, Microbrochis, Phlebiogonium, and Sagenia, sampled here for the first time, are resolved as part of Tectaria; (3) four superclades representing early splits in Tectaria are identified, with the Old World species being sister to the New World species; (4) 12 well-supported major clades in Tectaria are revealed, differing from one another in molecular, morphological, and geographical features; (5) evolution of 13 morphological characters is inferred in a phylogenetic context and morphological synapomorphies of various clades are identified; and in particular (6) free venation in Tectaria is inferred to be repeatedly derived from anastomosing venation, an evolutionary phenomenon not documented previously in vascular plants in a phylogenetic context based on both plastid and nuclear evidence. (C) 2017 Elsevier Inc. All rights reserved
Ecological Succession Pattern of Fungal Community in Soil along a Retreating Glacier
No full textAccelerated by global climate changing, retreating glaciers leave behind soil chronosequences of primary succession. Current knowledge of primary succession is mainly from studies of vegetation dynamics, whereas information about belowground microbes remains unclear. Here, we combined shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. We investigated fungal succession and community assembly via high-throughput sequencing along a well-established glacier forefront chronosequence that spans 2-188 years of deglaciation. Shannon diversity and evenness peaked at a distance of 370m and declined afterwards. The response of fungal diversity to distance varied in different phyla. Basidiomycota Shannon diversity significantly decreased with distance, while the pattern of Rozellomycota Shannon diversity was unimodal. Abundance of most frequencies OTU2 (Cryptococcus terricola) increased with successional distance, whereas that of OTU65 (Tolypocladium tundrense) decreased. Based on null deviation analyses, composition of the fungal community was initially governed by deterministic processes strongly but later less deterministic processes. Our results revealed that distance, altitude, soil microbial biomass carbon, soil microbial biomass nitrogen and NH4+-N significantly correlated with fungal community composition along the chronosequence. These results suggest that the drivers of fungal community are dynamics in a glacier chronosequence, that may relate to fungal ecophysiological traits and adaptation in an evolving ecosystem. The information will provide understanding the mechanistic underpinnings of microbial community assembly during ecosystem succession under different scales and scenario
Molecular phylogenetics and historical biogeography of Sorbus sensu stricto (Rosaceae)
No full textExplaining how plants from eastern Asia migrated to other Northern Hemisphere regions is still challenging. The genus Sorbus sensu stricto (including c. 88 species) is considered as a good example to illuminate this scenario, due to the wide distribution in the temperate zone and high diversity in the Himalayas and Hengduan Mountains. Based on four nuclear markers (LEAFY-2, GBSSI-1, SBEI and WD) and one chloroplast marker (rps16-tmK), we reconstructed the phylogenetic relationship of Sorbus using 54 taxa (60% of the genus representing all subgenera, sections, or series and geographical areas in the previous classifications), and estimated divergence time and historical biogeography of the genus. Phylogenetic analyses supported that the subgenera Sorbus and Albo-carmesinae, as defined by traditional morphological characters (such as fruit color), are suitable. However, five clades defined by phylogenetic analysis of the genus are not consistent with traditionally defined sections or series. Molecular dating and biogeographic reconstruction showed that the age of the most recent common ancestor was estimated at 41 mya (95% HPD: 49-35 mya) in eastern Asia. Four dispersal events are assumed to explain the wide distribution of Sorbus in the temperate zone and diversification in the edges of Qinghai-Tibet Plateau (QTP). Species dispersed from eastern Asia to the Tianshan Mountains, North America and Europe during the Oligocene and Miocene period. We found that polyploidization occurred multiple times in the subgenus Albo-carmesinae, in the Tianshan Mountains, Himalayas, and H-D Mountains. Finally, we suggest that apomixis, polyploidization, and hybridization may have combined with the multistage uplifting of Himalayas and H-D Mountains (and the subsequent increases in geologic, ecological and climatic heterogeneity) to drive the striking species diversity of Sorbus in this region. (C) 2017 Elsevier Inc. All rights reserved
Polystichum tiandengense (subg. Haplopolystichum; Dryopieridaceae), a New Cave Fern from Guangxi, China
No full textA new fern species, Polystichum tiandengense H. He & Li Bing Zhang (Dryopteridaceae), is described and illustrated from a limestone cave in the Guangxi Zhuangzu Autonomous Region, South China. Polystichum tiandengense is most similar to P. cavernicola. Li Bing Zhang & H. lie in having oblong to square pinnae with undulate margins, but the new species is distinguished by its pinnae mostly adjacent to each other or imbricating, and mostly sterile (vs. distant from each other and mostly fertile in P. cavernicola). Polystichum tiandengense is considered to be Critically Endangered (CR), based on RICN Red List criteria
Copper-Catalyzed Direct Oxyphosphorylation of Enamides with P(O)-H Compounds and Dioxygen
No full textA simple and convenient copper-catalyzed direct oxyphosphorylation of enamides with P(O)-H compounds and dioxygen has been developed under mild conditions. This methodology can allow the synthesis of a series of valuable -ketophosphine oxides/-ketophosphonates in moderate to good yields with a broad substrate scope simply by using readily-available starting materials
Substrate stiffness governs the initiation of B cell activation by the concerted signaling of PKC beta and focal adhesion kinase
No full textThe mechanosensing ability of lymphocytes regulates their activation in response to antigen stimulation, but the underlying mechanism remains unexplored. Here, we report that B cell mechanosensing-governed activation requires BCR signaling molecules. PMA-induced activation of PKC beta can bypass the Btk and PLC-gamma 2 signaling molecules that are usually required for B cells to discriminate substrate stiffness. Instead, PKC beta-dependent activation of FAK is required, leading to FAK-mediated potentiation of B cell spreading and adhesion responses. FAK inactivation or deficiency impaired B cell discrimination of substrate stiffness. Conversely, adhesion molecules greatly enhanced this capability of B cells. Lastly, B cells derived from rheumatoid arthritis (RA) patients exhibited an altered BCR response to substrate stiffness in comparison with healthy controls. These results provide a molecular explanation of how initiation of B cell activation discriminates substrate stiffness through a PKC beta-mediated FAK activation dependent manner
Three new chlorinated phenolic glycosides from Przewalskia tangutica
No full textThree new chlorinated phenolic glycosides, namely przewatangosides A-C (1-3), along with one known compound, globosumoside A (4), were isolated from the whole plants of Przewalskia tangutica. Their structures were unequivocally determined by extensive spectroscopic analysis and chemical method. The cytotoxic activities of the isolated phenolic glycosides (1-4) were evaluated against the five human cancer cell lines A549, MCF-7, SMMC-7721, HepG2 and HL-60. Przewatangoside A (1) exhibited weak cytotoxicity against SMMC-7721 with the IC50 value of 38.1 mu M. All the tested compounds were inactive (IC50 > 50 mu M) to the normal human hepatocyte cell line (L02)
Organic nanostructure-based probes for two-photon imaging of mitochondria and microbes with emission between 430 nm and 640 nm
No full textMulti-photon excitation and versatile fluorescent probes are in high need for biological imaging, since one probe can satisfy many needs as a biosensor. Herein we synthesize a series of two-photon excited probes based on tetraphenylethene (TPE) structures (TPE-Acr, TPE-Py, and TPE-Quino), which can image both mammalian cells and bacteria based on aggregation-induced emission (AIE) without washing them. Because of cationic moieties, the fluorescent molecules can aggregate into nanoscale fluorescent organic nanoscale dots to image mitochondria and bacteria with tunable emissions using both one-photon and two-photon excitation. Our research demonstrates that these AIE-dots expand the functions of luminescent organic dots to construct efficient fluorescent sensors applicable to both one-photon and two-photon excitation for bio-imaging of bacteria and mammalian cells
Transition-metal-free PhI(OAc)(2)-promoted highly selective hydroboration of terminal alkynes under air
No full textA new transition-metal-free PhI(OAc)(2)-promoted hydroboration reaction of terminal alkynes with bis(pinacolato) diboron has been developed at room temperature under air. A series of vinyl boronates could be conveniently and efficiently obtained in moderate to good yields with good regioselectivity and stereoselectivity as well as favorable functional group tolerance. The key I-B intermediates were first demonstrated in the present reaction system that explains the proposed mechanism
CuBr_2/Ag_2CO_3催化苄胺氧化酰胺化合成N-苄基苯甲酰胺
No full text目的建立一种简单、有效地制备N-苄基苯甲酰胺类化合物的方法。方法以苄胺及衍生物为底物、TBHP为氧化剂、HPO(OEt)_2为添加剂,在CuBr_2/Ag_2CO_3的催化下,制备N-苄基苯甲酰胺类化合物。结果和讨论制备了一系列N-苄基苯甲酰胺类化合物,其结构经~1HNMR、~(13)CNMR和HR-MS表征。该反应具有操作简便、原料易得、条件温和等特点