Nurse turnover research in China:A bibliometric analysis from 2000 to 2015

Objectives:The study was conducted to make a bibliometric analysis of published literature in order to assess the research status of nurse turnover in China.Methods:We obtained 239 papers from two major electronic databases,CNKI and Wanfang from 2000 to 2015(updated to 31st,December).Articles in languages other than Chinese were excluded.The keywords used were‘nurses’or‘nursing staff’and‘leave’or‘intend to leave’.Results:A total of 239 articles met the inclusion criteria,including 33 masters'dissertations and 206 journal articles.206 articles were published in twenty-five kinds of journals in China.Nursing journals had the biggest share,about(88%,181/206).82%(196/239)articles are quantitative research.239 articles come from 26 different provinces,cities or autonomous regions.The top ten regions which have the largest number of publications are Beijing,Shandong,Shanghai,Guangdong,Heilongjiang,Jiangsu,Hunan,Zhejiang,Hubei,Liaoning provinces.The coauthored articles account for 75%of all the publications.Only a small fraction of research works has obtained fundings.Conclusion:Further studies are greatly needed on the development of sound measures to tackle nurse turnover and shortage.The following improvements should be made,such as strengthening nursing researcher'consciousness and capability and increasing nursing fundings in China.

A chromosome-level,haplotype-phased Vanilla planifolia genome highlights the challenge of partial endoreplication for accurate wholegenome assembly

Vanilla planifolia, the species cultivated to produce one of the world’s most popular flavors, is highly proneto partial genome endoreplication, which leads to highly unbalanced DNA content in cells. We report herethe first molecular evidence of partial endoreplication at the chromosome scale by the assembly and annotation of an accurate haplotype-phased genome of V. planifolia. Cytogenetic data demonstrated that thediploid genome size is 4.09 Gb, with 16 chromosome pairs, although aneuploid cells are frequentlyobserved. Using PacBio HiFi and optical mapping, we assembled and phased a diploid genome of 3.4 Gbwith a scaffold N50 of 1.2 Mb and 59 128 predicted protein-coding genes. The atypical k-mer frequenciesand the uneven sequencing depth observed agreed with our expectation of unbalanced genome representation. Sixty-seven percent of the genes were scattered over only 30% of the genome, putatively linkinggene-rich regions and the endoreplication phenomenon. By contrast, low-coverage regions (non-endoreplicated) were rich in repeated elements but also contained 33% of the annotated genes. Furthermore, this assembly showed distinct haplotype-specific sequencing depth variation patterns, suggesting complexmolecular regulation of endoreplication along the chromosomes. This high-quality, anchored assemblyrepresents 83% of the estimated V. planifolia genome. It provides a significant step toward the elucidationof this complex genome. To support post-genomics efforts, we developed the Vanilla Genome Hub, a userfriendly integrated web portal that enables centralized access to high-throughput genomic and other omicsdata and interoperable use of bioinformatics tools.

Design,synthesis,and biological evaluation of multiple targeting antimalarials

Malaria still threatens global health seriously today.While the current discoveries of antimalarials are almost totally focused on single mode-of-action inhibitors,multi-targeting inhibitors are highly desired to overcome the increasingly serious drug resistance.Here,we performed a structure-based drug design on mitochondrial respiratory chain of Plasmodium falciparum and identified an extremely potent molecule,RYL-581,which binds to multiple protein binding sites of P.falciparum simultaneously(allosteric site of type Ⅱ NADH dehydrogenase,Q_(o) and Q_(i) sites of cytochrome bc_(1)).Antimalarials with such multiple targeting mechanism of action have never been reported before.RYL-581 kills various drug-resistant strains in vitro and shows good solubility as well as in vivo activity.This structurebased strategy for designing RYL-581 from starting compound may be helpful for other medicinal chemistry projects in the future,especially for drug discovery on membrane-associated targets.

Structure, Diversity, and Evolution of a New Family of Soluble Carotenoid-Binding Proteins in Cyanobacteria

Using a phylogenomic approach, we have identified and subciassified a new family of carotenoid-binding proteins. These proteins have sequence homology to the N-terminal domain （NTD） of the Orange Carotenoid Protein （OCP）, and are referred to as Helical Carotenoid Proteins （HCPs）. These proteins comprise at least nine distinct ciades and are found in diverse organisms, frequently as multiple paralogs representing the distinct ciades. These seem to be out-paralogs maintained from ancient duplications associated with subfunctionalization. All of the HCPs share conservation of the residues for carotenoid binding, and we confirm that carotenoid binding is a fundamental property of HCPso We solved two crystal structures of the Nostoc sp. PCC 7120 HCP1 protein, each binding a different carotenoid, suggesting that the proteins flexibly bind a range of carotenoids. Based on a comprehensive phylogenetic analysis, we propose that one of the HCP subtypes is likely the evolutionary ancestor of the NTD of the OCP, which arose following a domain fusion evenS. However, we predict that the majority of HCPs have functions distinct from the NTD of the OCP. Our results demonstrate that the HCPs are a new family of functionally diverse carotenoid-binding proteins found among ecophysiologically diverse cyanobacteria.

Carl Woese:Still ahead of our time

The work of Carl Woese and his colleagues of the Urbana University has been one of the most important breakthroughs in biology in the last century(for historical sketches,see Refs.1,2).Carl Woese pioneered the use of macromolecule sequences to decipher the relationships between all organisms,fulfilling Darwin's dream to get a“fairly true genealogical trees of each great kingdom of nature”3.He went even beyond this objective since he was finally able to identify and connect each great kingdom of nature(which he called domains)into a single tree.The apex of his work was the discovery in 1977 of an entire new domain of life,hidden before our eyes,the Archaea4.The use of 16S ribosomal RNA(rRNA)as a molecular chronometer and later as a probe for PCR not only revealed a third domain of life but also paved the way for the detection and identification of microorganisms that were not yet amenable to cultivation5.

Nondestructive and Fast Vibration Phenotyping of Plants

The frequencies of free oscillations of plants,or plant parts,depend on their geometries,stiffnesses,and masses.Besides direct biomechanical interest,free frequencies also provide insights into plant properties that can usually only bemeasured destructively or with low-throughput techniques(e.g.,change inmass,tissue density,or stiffness over development or with stresses).We propose here a new high-throughput method based on the noncontact measurements of the free frequencies of the standing plant.The plant is excited by short air pulses(typically 100ms).The resulting motion is recorded by a high speed video camera(100 fps)and processed using fast space and time correlation algorithms.In less than aminute the mechanical behavior of the plant is tested over several directions.The performance and versatility of this method has been tested in three contrasted species:tobacco(Nicotiana benthamian),wheat(Triticum aestivum L.),and poplar(Populus sp.),for a total ofmore than 4000 data points.In tobaccowe show that water stress decreased the free frequency by 15%.In wheat we could detect variations of less than 1 g in the mass of spikes.In poplar we could measure frequencies of both the whole stem and leaves.The work provides insight into new potential directions for development of phenotyping.

The expanding Asgard archaea and their elusive relationships with Eukarya

The discovery of Asgard archaea and the exploration of their diversity over the last 6 years have deeply impacted the scientific community working on eukaryogenesis,rejuvenating an intense debate on the topology of the universal tree of life(uTol).Here,we discuss how this debate is impacted by two recent publications that expand the number of Asgard lineages and eukaryotic signature proteins(ESPs).We discuss some of the main difficulties that can impair the phylogenetic reconstructions of the uTol and suggest that the debate about its topology is not settled.We notably hypothesize the existence of horizontal gene transfers between ancestral Asgards and proto-eukaryotes that could result in the observed abnormal behaviors of some Asgard ESPs and universal marker proteins.This hypothesis is relevant regardless of the scenario considered regarding eukaryogenesis.It implies that the Asgards were already diversified before the last eukaryotic common ancestor and shared the same biotopes with proto-eukaryotes.We suggest that some Asgards might be still living in symbiosis today with modern Eukarya.

Importing Manganese into the Chloroplast： Many Membranes to Cross

Manganese （Mn） plays a wealth of roles in living systems. It is ubiquitously involved in the antioxidant response because of its ability to catalyze the dismutation of superoxide anions. In eukaryotic cells, Mn also plays a role in protein glycosylation in the secretory system. However, arguably, in photosynthetic organisms, the most important role of Mn is in the oxygen evolving complex at photosystem IL （PS Ⅱ）. Atthe global level, atmospheric oxygen is derived from the splitting of water, a reaction that relies strictly on the tetra-manganese cluster （Mn405Ca） bound to photosystem II at the lumen side of the thylakoid membrane.

A Phelipanche ramosa KAI2 protein perceives strigolactones and isothiocyanates enzymatically

Phelipanche ramosa is an obligate root-parasitic weed that threatens major crops in central Europe.In order to germinate,it must perceive various structurally divergent host-exuded signals,including isothiocyanates(ITCs)and strigolactones(SLs).However,the receptors involved are still uncharacterized.Here,we identify five putative SL receptors in P.ramosa and show that PrKAI2d3 is involved in the stimulation of seed germination.We demonstrate the high plasticity of PrKAI2d3,which allows it to interact with different chemicals,including ITCs.The SL perception mechanism of PrKAI2d3 is similar to that of endogenous SLs in non-parasitic plants.We provide evidence that PrKAI2d3 enzymatic activity confers hypersensitivity to SLs.Additionally,we demonstrate that methylbutenolide-OH binds PrKAI2d3 and stimulates P.ramosa germination with bioactivity comparable to that of ITCs.This study demonstrates that P.ramosa has extended its signal perception system during evolution,a fact that should be considered for the development of specific and efficient biocontrol methods.