Plasmid metagenome reveals high levels of antibiotic resistance genes and mobile genetic elements in activated sludge

The overuse or misuse of antibiotics has accelerated antibiotic resistance, creating a major challenge for the public health in the world. Sewage treatment plants (STPs) are considered as important reservoirs for antibiotic resistance genes (ARGs) and activated sludge characterized with high microbial density and diversity facilitates ARG horizontal gene transfer (HGT) via mobile genetic elements (MGEs). However, little is known regarding the pool of ARGs and MGEs in sludge microbiome. In this study, the transposon aided capture (TRACA) system was employed to isolate novel plasmids from activated sludge of one STP in Hong Kong, China. We also used Illumina Hiseq 2000 high-throughput sequencing and metagenomics analysis to investigate the plasmid metagenome. Two novel plasmids were acquired from the sludge microbiome by using TRACA system and one novel plasmid was identified through metagenomics analysis. Our results revealed high levels of various ARGs as well as MGEs for HGT, including integrons, transposons and plasmids. The application of the TRACA system to isolate novel plasmids from the environmental metagenome, coupled with subsequent high-throughput sequencing and metagenomic analysis, highlighted the prevalence of ARGs and MGEs in microbial community of STPs.     

不同苹果砧穗组合的生长及光合特性

以‘垂丝海棠’（Malus halliana）和‘平邑甜茶’（Malus hupehensis）为基砧,分别嫁接品种‘烟富6号’和‘长富2号’接穗,测定4种砧穗组合的嫁接亲和性、接穗生长量、光合与荧光参数及叶绿素含量（SPAD）,并用主成分分析法综合评价砧穗组合的优劣,探讨不同苹果砧穗组合嫁接苗的生长及光合特性,为西北盐碱地选择适宜的苹果砧木提供理论依据。结果表明：（1）4种砧穗组合中‘垂丝海棠/烟富6号’的上下口粗度比最接近1,嫁接亲和性最好。（2）整个生长期内,以‘垂丝海棠’为基砧的2个组合嫁接苗的生长量、净光合速率（P_n）、最大荧光（F_m）、PSⅡ最大光能转化率（F_v/F_m）均显著大于‘平邑甜茶’为基砧的组合,但其胞间CO₂浓度（C_i）及初始荧光（F₀）显著低于‘平邑甜茶’为基砧的组合;光化学猝灭系数（qP）在4种砧穗组合中无显著差异。（3）在8月份光照强度较高时,‘垂丝海棠/烟富6号’ 嫁接苗的气孔导度（G_s）高于其他砧穗组合;以‘垂丝海棠’为基砧的2个组合嫁接苗叶片的蒸腾速率（T_r）和相对叶绿素含量（SPAD）显著高于‘平邑甜茶’ 基砧组合。（4）根据主成分分析对各项指标进行综合评价,按照4个砧穗组合的综合得分由高到低依次为：‘垂丝海棠/烟富6号’、‘垂丝海棠/长富2号’、‘平邑甜茶/长富2号’、‘平邑甜茶/烟富6号’。研究发现,基砧‘垂丝海棠’的适应性优于‘平邑甜茶’,且‘垂丝海棠/烟富6号’砧穗组合的嫁接亲和性高,长势强,光合能力优,为甘肃中部地区适宜的砧穗组合。     

猪PEG1基因多态性及其遗传印记

PEG1基因影响动物胚胎生长及母性行为,多数动物PEG1为父方表达的遗传印记特征,但出生后猪的PEG1印记表达尚不清楚。因此,文章选取长白、大白和蓝塘3个品种共166头纯种猪,在猪的PEG1基因外显子12区域内寻找SNP,采用PCR-SSCP方法对其多态性进行检测和基因频率分析;取带有PEG1基因该位点SNP为杂合的仔猪3头,对其胃、胸腺、胰、脾、肺、肌肉、肝、舌、肾、脑、膀胱、心脏等组织器官和胎盘的mRNA产物分别进行RT-PCR-SSCP分析,结果表明:PEG1基因外显子12存在一个由G突变为A的单核苷酸多态性位点;PEG1的外显子12在3头仔猪的主要组织器官仅表达父亲来源的等位基因,表明猪的PEG1基因呈母方印记、父方表达的遗传特征。     

应用排序分析藓类植物分类群分布与气候因素的关系

以我国21个山地藓类植物区系和气象资料为基础,应用典范对应分析(CCA)和除趋势典范对应分析(DCCA),比较了21个山地中藓类植物61个科,曲尾藓科(Dicranaceae)23个属、曲柄藓属(Campylopus)17种及曲尾藓属(Dicranum)35种分布与年均温度、>10℃积温、1月均温、7月均温、年均相对湿度、年均降雨量、年有雾天数、年有霜天数和年日照时数的关系,通过排序进行了直观的展示;同时还应用典范对应分析直观地反映了包括长白山在内的我国9个山地苔藓植物地理成分组成上的相似性及它们与气候因素间的关系.本文研究表明将DCCA和CCA应用到植物区系地理学研究上是可行的.     

Experimental Study of Low Dose Ultrashortwave Promoting Nerve Regeneration after Acellular Nerve Allografts Repairing the Sciatic Nerve Gap of Rats

Objectives To observe the effect of ultrashortwave (USW) therapy on nerve regeneration after acellular nerve allografts(ANA) repairing the sciatic nerve gap of rats and discuss its acting mechanisms. Methods Sixteen Wistar rats weighing 180–220 g were randomly divided into four groups with four rats in each group: normal control group; acellular group (ANA, treated by hypotonic-chemical detergent, was applied for bridging a 10 mm-long sciatic nerve defect); USW group (After 24 h of ANA repairing the sciatic nerve gap, low dose USW was administrated for 7 min, once a day, 20 times a course of treatment, three courses of treatment in all); and autografts group. 12 weeks after operation, a series of examinations was performed, including electrophysiological methods, the restoring rate of tibialis anterior muscle wet weight, histopathological observation (myelinated nerve number, myelin sheath thickness, and axon diameter), vascular endothelial growth factor (VEGF) mRNA expression of spinal cord, and muscle at injury site, and analyzed statistically. Results Compared to acellular nerve allografts alone, USW therapy can increase nerve conductive velocity, the restoring rate of tibialis anterior muscle wet weight, myelinated nerve number, axon diameter, VEGF mRNA expression of spinal cord, and muscle at injury site, the difference is significant. There were no differences between USW group and autografts group except myelin sheath thickness. Conclusions USW therapy can promote nerve axon regeneration and Schwann cells proliferation after ANA repairing the sciatic nerve gap of rats, the upregulation of VEGF mRNA expression of spinal cord and muscle may play an important role.     

Enhancing Specific-Antibody Production to the ragB Vaccine with GITRL That Expand Tfh,IFN-γ+ T Cells and Attenuates Porphyromonas gingivalis Infection in Mice

The outer membrane protein RagB is one of the major virulence factors of the periodontal pathogen Porphyromonas gingivalis (P. gingivalis). In order to induce protective immune response against P. gingivalis infection, an mGITRL gene-linked ragB DNA vaccine (pIRES-ragB-mGITRL ) was constructed. Six-week-old female BALB/c mice were immunized with pIRES-ragB-mGITRL through intramuscular injection and then challenged by subcutaneous injection in the abdomen with P. gingivalis. RagB-specific antibody-forming cells were evaluated by an Enzyme-linked immunosorbent spot, and specific antibody was determined by enzyme-linked immunosorbent assay. In addition, the frequencies of Tfh and IFN-γ⁺ T cells in spleen were measured using flow cytometer, and the levels of IL-21 and IFN-γ mRNA or proteins were detected by real time RT-PCR or ELISA. The data showed that the mGITRL-linked ragB DNA vaccine induced higher levels of RagB-specific IgG in serum and RagB-specific antibody-forming cells in spleen. The frequencies of Tfh and IFN-γ⁺ T cells were obviously expanded in mice immunized by pIRES-ragB-mGITRL compared with other groups (pIRES or pIRES-ragB ). The levels of Tfh and IFN-γ⁺ T cells associated cytokines were also significantly increased in pIRES-ragB-mGITRL group. Therefore, the mice immunized with ragB plus mGITRL showed the stronger resistant to P. gingivalis infection and a significant reduction of the lesion size caused by P. gingivalis infection comparing with other groups. Taken together, our findings demonstrated that intramuscular injection of DNA vaccine ragB together with mGITRL induced protective immune response dramatically by increasing Tfh and IFN-γ⁺ T cells and antibody production to P. gingivalis.