基于NGS方法评估不同保存条件对粪便样本中菌群含量的影响

目的评估粪便样本的不同保存条件对肠道微生态研究结果的影响。方法设计相关实验,比较7种不同的保存方法,基于高通量测序技术比对不同时间、不同贮存温度对粪便样本DNA质量、菌群多样性及病原菌检出等结果之间的差异。结果证实了对于粪便样本采集仍建议采取即刻提取核酸或-20℃保存的方法。同时比较多种保存方法后发现,采用不同样本保存方法受到影响的菌属集中在低丰度菌属(≤0.01%),对应较高丰度的病原菌检测结果的可靠性影响较小,样本中丰度超过千分之一的病原菌检测率超过95%。结论对于肠道微生态研究建议对粪便样本采取即刻提取核酸或-20℃保存的方法。对于由于其他原因未能妥善保存的粪便样本(如常温保存48 h),仍可对丰度超过千分之一的病原菌进行检测。以上结果对于肠道菌群研究中异地所采集的粪便样本运输和贮存具有一定的指导意义。     

3种粪便标本保存方法对肠道菌群检测结果影响的比较研究

比较3种粪便标本保存方法对肠道菌群检测结果的影响,为采集粪便标本后短期保存方法的选择提供参考。收集10名志愿者的新鲜粪便标本,对每份标本分别采用4℃、室温(25℃)、无水乙醇保存4 h,然后统一放入-80℃低温冰箱冻存。随后进行细菌DNA提取,并对16S rRNA V4区基因进行扩增,应用Illumina MiSeq平台进行高通量测序,比较3种保存方法下肠道菌群多样性和组成差异。结果表明,3种保存方法下,肠道菌群在Alpha多样性方面无统计学差异(P0.05)。肠道菌群属水平比较,毛螺旋菌属(Lachnospira)在无水乙醇组中相对丰度高于4℃组和室温组(P0.05),萨特菌属(Sutterella)在无水乙醇组中相对丰度高于4℃组(P0.05),而真杆菌属(Eubacterium)在无水乙醇组中相对丰度低于室温组(P0.05)。PCoA分析发现,当UniFrac距离加权后,4℃和无水乙醇保存同一受试者粪便标本,菌群结果较为接近,而室温保存会导致个别受试者菌群出现离散现象。无水乙醇短期保存粪便标本,肠道菌群多样性、组成以及结构保持稳定,能满足不同研究的需要。此外,无水乙醇具备价格低廉、便于携带等优点。因此,在新鲜粪便标本不能立即低温冻存时,无水乙醇保存可以作为首要选择。     

粪便留取量对粪便中细菌结构和功能的影响CSCD

目的探究不同粪便留取量对肠道菌群构成研究结果的影响,为肠道菌群构成研究中粪便样本的采集方式提供参考。方法本研究分别对全便和部分粪便进行预处理,并使用PacBio SMRT测序技术对10名志愿者的20份粪便样本进行了16S rRNA全长测序,通过多元统计学等手段对粪便中细菌的构成、多样性和功能进行比较分析。结果Eubacterium rectale、Eubacterium ventriosum和Allisonella histaminiformans等低丰度物种的相对丰度在不同粪便留取量中有一定差异,其在全便中的相对丰度均显著高于部分粪便(P<0.05)。但Wilcoxon配对检验发现粪便留取量对肠道菌群结构、多样性和功能的影响均无显著性差异(P>0.05)。不同个体间肠道菌群结构存在明显差异,且粪便留取量的影响远小于个体差异。结论全便和部分粪便两种粪便留取量对检测微生物的组成、多样性和功能无显著影响,因此取部分粪便即可满足对肠道菌群研究的要求。     

粪便样本不同保存方式对肠道菌群测序结果的影响

[目的]本文探究了3种室温保存剂和-80℃C冷冻保存对粪便样本中菌群结构的影响,为大规模、标准化的采样提供参考.[方法]本研究采集了5名健康志愿者的新鲜粪便作为测试样本,采用4种不同的保存方式保存:DETs室温保存、GITC室温保存、RNAlater室温保存和-80℃冷冻保存,在保存0、1、3、7、14、28 d后,采...     

基于16S rRNA基因测序比较分析不同抗生素干预对小鼠肠道菌群动态变化的影响

目的探讨不同种类抗生素对小鼠肠道菌群多样性和组成动态变化的影响。方法采用健康SPF级雌性C57BL/6小鼠20只随机分为对照组(CON组)6只、万古霉素组(VAN组)6只和多黏菌素组(PMB组)8只,通过饮用抗生素方式连续处理5周,于3周、5周采集小鼠粪便样本进行16S rRNA基因的V4-V5区测序。结果与CON组相比,VAN组处理3周和5周菌群多样性显著降低,以疣微菌门(阿克曼菌科)、变形菌门(肠杆菌科)及无胆支原体科相对丰度显著增加,拟杆菌门(Muribaculaceae菌科、普雷沃菌科)和毛螺菌科显著减少为特征(P均0.05)。PMB组处理3周后,菌群多样性显著增加,以普雷沃菌科和毛螺菌科相对丰度显著增加,疣微菌门(阿克曼菌科)和Muribaculaceae菌科显著减少为特征。PMB处理5周后,菌群多样性显著降低,以疣微菌门(阿克曼菌科)相对丰度显著增加,而厚壁菌门(毛螺菌科)显著减少为特征(P均0.05)。结论用不同种类的抗生素处理不同时间后小鼠肠道菌群组成不同,但多样性均显著降低,且抗生素处理时间越长菌群多样性降低幅度越大,菌群种类越少。     

早产儿高胆红素血症与肠道菌群的相关性

目的探讨高胆红素血症早产儿与非高胆红素血症早产儿肠道菌群的差异,为该病的治疗提供思路和依据。方法选择2017年1月至6月出生后即在本院新生儿科治疗的早产儿(胎龄35+1～36+6周)为研究对象,其中高胆红素血症早产儿(黄疸组)124例,非高胆红素血症早产儿(对照组)118例。采集两组对象出生后24 h内的首次胎便,采用高通量测序技术对粪便样本中细菌16S rRNA基因进行检测,分析肠道菌群组成情况。结果黄疸组早产儿肠道微生物群落组成与对照组在门水平上相似度较高。在属水平上,两组对象肠道菌群均以Ralstonia、Rhodococcus、Enterococcus为主。对照组患儿肠道Lactobacillus的相对丰度显著高于黄疸组(t=-2.073 0,P=0.039 1)。黄疸组患儿肠道Ralstonia的相对丰度与总胆红素水平呈负相关(r=-0.314 8,P=0.000 3)。结论高胆红素血症早产儿与非高胆红素血症早产儿肠道菌群的种类和丰度存在差异。Lactobacillus可能是高胆红素血症的潜在生物标记物。     

蛇鮈精子保存液的筛选及其效果研究

旨在研究不同精子保存液对蛇鮈精子活率的影响,并探讨保存蛇鮈精子的最佳保存液。在光镜下观察6种精子保存液保存蛇鮈精子后精子活率的变化,结果表明精子保存液在低温(4℃)保存蛇鮈精子的方法效果较好。6种蛇鮈精子保存液使精子的活率保持为80%的时间有着明显的差异:A液为36 h,B液为4 h,C液为0 h,D液为60h,E液为16 h,F液为6 h,因此在低温(4℃)下,蛇鮈精子的最佳保存液为D液。     

核心岩藻糖基转移酶Fut8基因敲除小鼠肠道菌群特征

目的探究Fut8基因敲除对ICR小鼠肠道菌群结构的影响。方法分别在Fut8~(+/+)和Fut8~(-/-)小鼠出生后不同时间点检测体重,采集粪便样本,采用PCR-变性梯度凝胶电泳(PCR-DGGE)的方法检测小鼠粪便中菌群的组成;利用高效液相色谱法(HPLC)测定Fut8~(+/+)和Fut8~(-/-)小鼠Fut8酶活。结果 Fut8~(-/-)小鼠与Fut8~(+/+)小鼠相比生长缓慢(P0.05);完全丧失核心岩藻糖基化活性;肠道菌群结构不同,其中拟杆菌门微生物存在显著差异。结论核心岩藻糖基转移酶Fut8基因敲除对小鼠肠道菌群结构有显著影响。     

链脲佐菌素诱导糖尿病大鼠模型肠道菌群变化

目的观察链脲佐菌素(streptozotocin,STZ)诱导糖尿病大鼠模型肠道菌群结构和丰度的变化。方法雄性SD大鼠25只,随机分为对照组(C)10只、模型组(M)15只。模型组腹腔注射3%的STZ,剂量30 mg/(kg·bw),连续5 d。成模后每月测量体重、血糖等指标。模型成立4周和12周时,分别在同一时间取各组大鼠的新鲜直肠粪便。在Illumina高通量测序平台上对粪便样本中细菌16S r DNA-V3区进行测序,对肠道菌群结构、丰度进行定量分析。结果模型组和对照组获得的优化序列数差异无显著性(P0.05)。模型组动物肠道菌群的相对丰度指数(Chao1)、多样性指数Shannon与对照组比较降低(P0.05),Simpson指数与对照组比较升高(P0.05)。在门水平,变形菌门(Proteobacteria)、蓝藻菌门(Cyanobacteria)、软壁菌门(Tenericutes)、TM7、放线菌门(Actinobacter)相对丰度降低(P0.05)。在属水平,造模4周,模型组乳杆菌属(Lactobacillus)相对丰度降低(P0.05);拟杆菌属(Bacteroides)相对丰度升高(P0.05)。造模12周,模型组乳杆菌属(Lactobacillus)、拟杆菌属(Bacteroides)、瘤胃球菌属(Ruminococcus)相对丰度升高(P0.05);双歧杆菌属(Bifidobacterium)相对丰度降低(P0.05)。结论 STZ诱导的SD大鼠糖尿病动物肠道菌群的丰度和多样性降低,为糖尿病与肠道菌群关系研究提供参考。     

益生菌Lactobacillus paracasei subsp.paracasei Zhang对海南地区部分青年人肠道菌群的影响

【目的】以海南地区征集的29名健康青年志愿者为研究对象,分析该地区青年人肠道菌群多样性,并探究益生菌Lactobacillus paracasei subsp. paracasei Zhang (LCZ)对其肠道菌群的影响。【方法】29名健康青年志愿者每日补充2 g益生菌LCZ (0.5×10~(10)CFU/g),为期14 d。采集摄入益生菌LCZ第0、14、28天的志愿者粪便样品,采用Pac Bio SMRT测序技术基于16S rRNA基因全长测序分析志愿者粪便微生物组成和结构,评估益生菌LCZ对其肠道菌群的影响。【结果】在门水平上,Firmicutes (54.46%)和Bacteroidetes (33.79%)在志愿者粪便微生物中含量最高;在属水平上,Bacteroides (23.13%)的相对含量最高;在种水平上,优势菌种为Faecalibacterium prausnitzii (9.72%)、Eubacterium rectale (7.00%)和Prevotella copri (6.07%)等。摄入益生菌LCZ 14 d后,肠道中的优势菌属变化不显著,低丰度菌属如Oscillospira和Parabacteroides等显著增加,Aeromonas和Fusicatenibacter等显著减少(P0.05)。此外根据志愿者粪便中Lactobacillus含量的变化情况,将所有志愿者分为两组。其中一组志愿者在摄入LCZ后粪便中Lactobacillus菌属相对含量显著增加,同时该组志愿者肠道中其他菌种如Butyricicoccus pullicaecorum、Lactococcus raffinolactis和Parabacteroides distasoni亦显著增加;而另一组志愿者,Lactobacillus及上述菌种均未发生显著变化。【结论】连续2周摄入益生菌LCZ对志愿者肠道菌群中优势菌属的相对丰度影响不显著,但对低丰度菌属的相对丰度影响显著。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.