Evidence of compliance with and effectiveness of guidelines for noninvasive prenatal testing in China: a retrospective study of 189,809 cases

In China,the medical guidelines recommend performing noninvasive prenatal testing (NIPT) with caution for pregnant women aged 35 years or older.However,the Mother and Child Health Care Law suggests that all primiparous women whose age is older than 35 years undergo prenatal diagnosis.These two inconsistent suggestions/recommendations have made obstetricians confused about whether to offer NIPT to these older pregnant women.To face this issue and find out the solution we performed a retrospective study of 189,809 NIPT samples collected from 28 provincial-leveled administrative units in China.Of 1,564women with high-risk pregnancies who underwent NIPT,459 (29.3%) did not participate in follow-up.The compound sensitivity and specificity of NIPT for trisomies 21,18 and 13 detection was 99.1%(95%CI,98.0%-99.6%) and 99.9%(95%CI,98.8%-99.9%),respectively.In secundiparous women,NIPT showed high sensitivity and specificity similar to that in primiparous women.The observed risk for trisomies 21 and 18 significantly increased when the maternal age was 39 and older.After the publication of the current NIPT policy,the follow-up rate at our center was 97.9%;however,a large number of women are not in maternal and infant care networks nationwide,and that makes the follow-up rate outside our center relatively low.Our study shows that to balance the prevention of major aneuploidies and the limited resources for prenatal diagnosis,the cut-off age of 35for invasive prenatal diagnosis might be unnecessary.Although the NIPT guidelines are well written,how to practice it effectively,especially in less industrialized areas,is worth discussing.     

RHCG基因在非小细胞肺癌中的表达及对细胞增殖的影响

为了探讨Rh type C glycoprotein (RHCG)对非小细胞肺癌(non-small cell lung cancer,NSCLC)细胞增殖的影响及可能的作用机制,本研究使用荧光定量PCR法检测12对NSCLC及癌旁组织样本中RHCG mRNA的表达水平及pcDNA3.1-RHCG质粒对A549细胞RHCG m RNA的表达;采用CCK-8法检测细胞增殖能力;运用PI染色法检测细胞周期;使用免疫印迹法检p-PI3K、PI3K、p-AKT以及AKT蛋白表达水平。本研究发现,与癌旁组织比较,NSCLC中RHCG m RNA表达水平明显降低。RHCG过表达能抑制NSCLC细胞系A549细胞增殖能力。此外,RHCG过表达使A549细胞周期G1/S期转化发生阻滞。本研究还发现,RHCG过表达可下调A549细胞p-PI3K/PI3K和p-AKT/AKT水平。本研究表明,RHCG抑制NSCLC细胞增殖的作用与其抑制PI3K/AKT信号通路有关。     

Molecular phylogeny and species delimitation of Stachyuraceae: Advocating a herbarium specimen‐based phylogenomic approach in resolving species boundaries

Species concept and delimitation are fundamental to taxonomic and evolutionary studies. Both inadequate informative sites in the molecular data and limited taxon sampling have often led to poor phylogenetic resolution and incorrect species delineation. Recently, the whole chloroplast genome sequences from extensive herbarium specimen samples have been shown to be effective to amend the problem. Stachyuraceae are a small family consisting of only one genus Stachyurus of six to 16 species. However, species delimitation in Stachyurus has been highly controversial because of few and generally unstable morphological characters used for classification. In this study, we sampled 69 individuals of seven species (each with at least three individuals) covering the entire taxonomic diversity, geographic range, and morphological variation of Stachyurus from herbarium specimens for genome‐wide plastid gene sequencing to address species delineation in the genus. We obtained high‐quality DNAs from specimens using a recently developed DNA reconstruction technique. We first assembled four whole chloroplast genome sequences. Based on the chloroplast genome and one nuclear ribosomal DNA sequence of Stachyurus, we designed primers for multiplex polymerase chain reaction and high throughput sequencing of 44 plastid loci for species of Stachyurus. Data of these chloroplast DNA and nuclear ribosomal DNA internal transcribed spacer sequences were used for phylogenetic analyses. The phylogenetic results showed that the Japanese species Stachyurus praecox Siebold & Zucc. was sister to the rest in mainland China, which indicated a typical Sino‐Japanese distribution pattern. Based on diagnostic morphological characters, distinct distributional range, and monophyly of each clade, we redefined seven species for Stachyurus following an integrative species concept, and revised the taxonomy of the family based on previous reports and specimens, in particular the type specimens. Furthermore, our divergence time estimation results suggested that Stachyuraceae split from its sister group Crossosomataceae from the New World at ca. 54.29 Mya, but extant species of Stachyuraceae started their diversification only recently at ca. 6.85 Mya. Diversification time of Stachyurus in mainland China was estimated to be ca. 4.45 Mya. This research has provided an example of using the herbarium specimen‐based phylogenomic approach in resolving species boundaries in a taxonomically difficult genus.     

芍药乙烯受体PlETR1基因过表达载体的构建及烟草转化

芍药是乙烯敏感型花卉,乙烯受体感知并传导乙烯信号,在乙烯信号转导途径中发挥重要作用。芍药PlETR1基因cDNA全长序列已分离,为了鉴定芍药PlETR1基因的功能,本研究基于PlETR1基因和表达载体序列,应用Primer Premier 5.0软件设计了一对特异性PCR引物,采用RT-PCR技术扩增出了PlETR1编码区片段,进一步构建了芍药PlETR1基因过表达载体。基于优化的模式植物烟草的组培体系和筛选出的潮霉素抗性浓度,应用农杆菌介导的叶盘法开展了芍药PlETR1基因转化烟草的研究,对转基因抗性烟草植株进行了PCR检测,结果表明HPT基因和芍药PlETR1基因已导入到烟草基因组中,且芍药PlETR1基因转录表达成功,为下一步鉴定芍药PlETR1基因的功能提供科学依据。     

绵马贯众多糖超声提取工艺优化及抗氧化活性分析

绵马贯众是中国传统常用中药,本研究以温度、时间、超声功率、液料比为影响因子,多糖得率为评价指标,通过响应面法优化超声辅助提取绵马贯众多糖的工艺条件,同时测定其基本理化性质及抗氧化活性。研究结果表明,绵马贯众多糖的最佳提取工艺条件为:温度64℃、时间60 min、超声功率210 W、液料比27 mL/g。此时多糖得率为9.57%,与预测值接近。理化性质分析表明绵马贯众多糖为含少量蛋白的酸性多糖。体外抗氧化研究表明绵马贯众多糖具有很强的DPPH自由基清除活性,IC50值为0.29 mg/mL;较好的羟基自由基清除活性,其IC50值为1.10 mg/mL;对DNA的氧化损伤有显著的保护作用。绵马贯众多糖可以作为一种潜在的抗氧化剂应用于食品和化妆品等领域。     

Allotransplantation of adult spinal cord tissues after complete transected spinal cord injury: Long-term survival and functional recovery in canines

Science China Life Sciences - Spinal cord injury (SCI), especially complete transected SCI, leads to loss of cells and extracellular matrix and functional impairments. In a previous study, we...     

基于线粒体基因分析蓝孔雀与绿孔雀的遗传差异

种间的遗传差异是物种分类和确定保护管理单元的基础,本研究利用DNA条形码技术对未知样本进行鉴定,通过NCBI进行BLAST得到结果是:与绿孔雀的同源性为96%。近一步通过对蓝孔雀(Pavo cristatus)和绿孔雀(Pavo muticus)线粒体细胞色素C氧化酶Ⅰ(cytochrome coxidaseⅠ,COⅠ)基因及线粒体基因组的比较分析,结果表明两物种间的COⅠ基因在碱基组成、核苷酸多样性等各项指标上均具有明显差异。遗传距离分析结果表明蓝孔雀与绿孔雀种内遗传距离为分别0和0.012,种间遗传距离为0.045,表明种间仍具有明显的遗传差异。通过对两物种线粒体基因组各基因的比较分析,发现ND1基因变异位点所占比例相对较高,考虑作为绿孔雀和蓝孔雀种群遗传学研究的最优分子标记。本研究将为分析孔雀类群间的系统发育及制定绿孔雀的保护措施提供了更多科学依据。     

Raman–deuterium isotope probing to study metabolic activities of single bacterial cells in human intestinal microbiota

Human intestinal microbiota is important to host health and is associated with various diseases. It is a challenge to identify the functions and metabolic activity of microorganisms at the single-cell level in gut microbial community. In this study, we applied Raman microspectroscopy and deuterium isotope probing (Raman–DIP) to quantitatively measure the metabolic activities of intestinal bacteria from two individuals and analysed lipids and phenylalanine metabolic pathways of functional microorganisms in situ. After anaerobically incubating the human faeces with heavy water (D₂O), D₂O with specific substrates (glucose, tyrosine, tryptophan and oleic acid) and deuterated glucose, the C–D band in single-cell Raman spectra appeared in some bacteria in faeces, due to the Raman shift from the C–H band. Such Raman shift was used to indicate the general metabolic activity and the activities in response to the specific substrates. In the two individuals' intestinal microbiota, the structures of the microbial communities were different and the general metabolic activities were 76 ± 1.0% and 30 ± 2.0%. We found that glucose, but not tyrosine, tryptophan and oleic acid, significantly stimulated metabolic activity of the intestinal bacteria. We also demonstrated that the bacteria within microbiota preferably used glucose to synthesize fatty acids in faeces environment, whilst they used glucose to synthesize phenylalanine in laboratory growth environment (e.g. LB medium). Our work provides a useful approach for investigating the metabolic activity in situ and revealing different pathways of human intestinal microbiota at the single-cell level.     

Exogenous maltose enhances Zebrafish immunity to levofloxacin-resistant Vibrio alginolyticus

Understanding the interplay between bacterial fitness, antibiotic resistance, host immunity and host metabolism could guide treatment and improve immunity against antibiotic-resistant pathogens. The acquisition of levofloxacin (Lev) resistance affects the fitness of Vibrio alginolyticus in vitro and in vivo. Lev-resistant (Lev-R) V. alginolyticus exhibits slow growth, reduced pathogenicity and greater resistance to killing by the host, Danio rerio (zebrafish), than Lev-sensitive (Lev-S) V. alginolyticus, suggesting that Lev-R V. alginolyticus triggers a weaker innate immune response in D. rerio than Lev-S V. alginolyticus. Differences were detected in the metabolome of D. rerio infected with Lev-S or Lev-R V. alginolyticus. Maltose, a crucial metabolite, is significantly downregulated in D. rerio infected with Lev-R V. alginolyticus, and exogenous maltose enhances the immune response of D. rerio to Lev-R V. alginolyticus, leading to better clearance of the infection. Furthermore, we demonstrate that exogenous maltose stimulates the host production of lysozyme and its binding to Lev-R V. alginolyticus, which depends on bacterial membrane potential. We suggest that exogenous exposure to crucial metabolites could be an effective strategy for treating and/or managing infections with antibiotic-resistant bacteria.     

Microbial assemblages associated with the rhizosphere and endosphere of an herbage,Leymus chinensis

Root-associated microbiomes play significant roles in plant productivity, health and ecological services. However, our current understanding of the microbial assemblages in the rhizosphere and endosphere of herbage is still limited. To gain insights into these microbial assemblages, Illumina MiSeq high-throughput sequencing was performed to investigate the characteristics of microbial communities of an herbage, Leymus chinensis. Hierarchical clustering analysis and principal coordinate analysis (PCoA) results showed that microbial communities of the rhizosphere and endosphere samples were clearly distinguished. Rhizosphere soil communities showed a greater sensitivity than root endosphere communities using linear discriminant analysis (LDA) effect size (LEfSe). Rhizosphere and endosphere communities performed their respective functions in the soil as a cohesive collective, and Rhizobiales were observed to function as generalists. Redundancy analysis (RDA) and variance partitioning analysis (VPA) results revealed that the contribution of the interaction between soil physicochemical parameters and soil enzymes was greater than their individual contributions. In summary, this study is the first to elucidate the microbial diversity and community structure of L. chinensis and compare the diversity and composition between rhizospheric and endosphere microbiomes.