巴松措原生动物群落结构季节及垂直分布

为揭示我国西藏高原湖泊原生动物群落结构特征及垂直分布格局,于2017年11月及2018年5月和9月,在巴松措中心分7层设置采样点,利用25号浮游生物网采集原生动物。采用活体观察和固定染色相结合的方法,共鉴定到原生动物195种(其中春季86种,夏季93种,秋季80种),隶属于2门11纲24目43科59属。其中以肉鞭门种类较丰富,砂壳类纤毛虫占优势。垂直分布的物种组成和群落结构复杂表现为：表层>中层>底层,物种多样性、丰富度和优势度指数表现为：表层>中层>底层,均匀度指数大多数为1;季节分布的物种组成和群落结构群复杂程度表现为：夏季>春季>秋季,物种多样性、丰富度指数表现为：夏季>秋季>春季,优势度指数表现为：夏季>秋季>春季,均匀度指数表现为：秋季>春季>夏季;优势物种和群落结构都会随水深的增加而减少。总体呈现出物种多样性较低、均匀度较高,具有明显的时空异质性。     

单细胞测序方法研究进展

近年来,高通量测序技术(Next-generation sequencing,NGS)快速发展,已广泛应用于生命科学各个领域,但传统的混合细胞测序(Bulk cell sequencing)检测的是细胞群体的总平均反应,无法反应每个细胞的真实情况,这会影响研究者对细胞功能认知的准确性。单细胞测序技术(Single cell sequencing,sc-Seq)的出现,从一定程度上解决了传统测序固有的缺陷。单细胞测序是针对单个细胞的RNA或DNA进行测序,能够准确测出单个细胞的基因结构和表达状态,从而分析相同表型细胞的异质性。本文首先介绍单细胞测序的原理、测序类型和测序平台,有助于理解单细胞测序和在进行科研项目时设计合适的项目方案。进一步介绍单细胞转录组测序的分析流程和各种常用的分析工具或软件,并重点阐述单细胞转录组测序分析中的细胞聚类和拟时序分析的原理和研究进展,为进行单细胞转录组测序数据分析提供参考。最后,本文简述了单细胞测序研究热度、单细胞测序的应用、挑战和展望等,有助于更全面地认识单细胞测序。     

鄂西北丹江口库区大气氮沉降

利用雨量器在鄂西北丹江口库区连续3a采集降雨样品,研究了大气氮沉降的变化动态。结果表明:2009—2011年月均总氮(TN)浓度为3.70—10.36 mg/L,与当月降雨量呈极显著线性负相关(R=-0.592**,n=32),季均TN浓度为冬季(8.21 mg/L)春季(3.94 mg/L)秋季(3.23 mg/L)夏季(2.70 mg/L),年均TN浓度为3.70 mg/L。大气氮素年均干湿总沉降量为26.53 kg/hm2,其中干沉降为7.80 kg/hm2,占总沉降量的29.4%;湿沉降为18.73 kg/hm2,占总沉降量的70.6%。干沉降中铵态氮(NH+4-N)、硝态氮(NO-3-N)、可溶性有机氮(DON)和颗粒态氮(PN)分别占TN的22.1%、16.8%、37.2%和23.9%,湿沉降中它们分别为TN的36.6%、34.4%、12.9%和16.1%。     

Abnormal Epidermal Keratinization in the repeated epilation mutant mouse

Repeated epilation (Er) is a radiation-induced, autosomal, incomplete dominant mutation in mice which is expressed in heterozygotes but is lethal in the homozygous condition. Many effects of the mutation occur in skin: the epidermis in Er/Er mice is adhesive (oral and nasal orifices fuse, limbs adhere to the body wall), hyperplastic, and fails to undergo terminal differentiation. Skin from fetal +/+, Er/+ and Er/Er mice at ages pre- and postkeratinization examined by light, scanning, and transmission electron microscopy showed marked abnormalities in tissue architecture, differentiation, and cell structure; light and dark basal epidermal cells were separated by wide intercellular spaces, joined by few desmosomes, and contained phagolysomes. The numbers of spinous, granular, and superficial layers were highly variable within any given region and among various regions of the body. In some areas, 2-8 layers of granular cells, containing large or diminutive keratohyalin granules, extended to the epidermal surface; in others, the granular layers were covered by several layers of partially keratinized or nonkeratinized cells. In rare instances, a single or small group of cornified cells was present among the granular layers but was not associated with the epidermal surface. Both the granular and nonkeratinized/partially keratinized upper epidermal layers Er/Er skin gave positive immunofluorescence with antiserum to the histidine-rich, basic protein, filaggrin. Proteins in epidermal extracts from +/+, Er/+ and Er/Er mice were separated and identified by radio- and immunolabeling techniques. The Er/Er extract was missing a 26.5- kdalton protein and had an altered ratio of bands in the keratin region. The 26.5-kdalton band was histidine-rich and cross-reacted with the antiserum to rat filaggrin. Several high molecular weight bands present in both Er/Er and +/+ extracts also reacted with the antiserum. These are presumed to be the precursors of filaggrin and to account for the immunofluorescence om Er/Er epidermis even though the product protein is absent. The morphologic and biochemical data indicated that the genetic defect has a general and profound influence on epidermal differentiation, including alteration of two proteins (filaggrin and keratin) important in normal terminal differentiation, tissue architecture, and cytology. Identification of epidermal abnormalities at early stages of development (prekeratinization) and defective structure of other tissues and gross anatomy suggest that the mutation is responsible for a defect in same regulatory step important in many processes of differentiation and development.     

Isolation and characterization of the major form of polyprenyl-phospho- mannose from Mycobacterium smegmatis

We isolated from the endogenous polyprenyl-phospho-sugar pool of Mycobacterium smegmatis two mannose-containing compounds, i.e., a partially saturated C35-octahydroheptaprenyl-P-mannose and a fully unsaturated C50-decaprenyl-P-mannose. The relative amount of C35- polyprenyl-P-mannose in mycobacterial cells was comparable to that of decaprenyl- P-pentoses and, at least, an order of magnitude higher than that of C50-decaprenyl-P-mannose. The major form of mycobacterial polyprenyl-P-mannose was structurally characterized by combined gas chromatography-mass spectrometry, fast-atom bombardment tandem mass spectrometry and proton-nuclear magnetic resonance spectroscopy as beta- d-mannopyranosyl-monophospho-(C35)octahydroheptapren ol of which all three isoprene units have Z ( cis ) configuration. The differences in the structure and cellular concentrations of the mycobacterial mannosyl- P-polyprenols reflect distinct biochemical pathways of the two compounds and suggest the existence of specific GDP-Man:polyprenyl-P mannosyltransferases (synthetases) able to distinguish between C35- octahydroheptaprenyl- and C50-decaprenyl- phosphates of mycobacteria. Since the 6'-O-mycoloylated form of C35-octahydroheptaprenyl-P-mannose isolated from M. smegmatis is apparently involved in mycolate rather than mannosyl transfer reactions, we speculate that a catabolic pathway responsible for degradation of C35-P-mannose and recycling C35- octahydroheptaprenyl phosphate might exist in mycobacteria.      

犬MC1R基因R306ter与毛色性状相关性研究

目的　分析犬MC1R基因中R30 6ter位点多态性与犬毛色表型的相关性 ,为遗传育种 ,培育出更加优良的实验用犬奠定基础。方法　采用PCR SSCP技术 ,对MC1R基因R30 6ter位点进行基因多态性检测 ,分析位点多态性与毛色性状之间的相关性 ,并对该位点进行克隆测序。结果　PCR SSCP分析结果表明 ,R30 6ter位点序列具有多态性 ,表现为C、D二个等位基因和CC、CD及DD三种基因型。对R30 6ter多态性片段克隆测序发现 ,MC1R基因在编码第 30 6位氨基酸的密码子处存在一个由CGA到TGA的终止突变。结论　经统计分析结果表明在杂种犬中MC1R基因多态性与毛色性状不存在显著的相关性 ,这可能是由于外科手术学教学用犬是杂种犬 ,其遗传背景不同所致。由于MC1R基因的R30 6ter位点内存在碱基变异 ,因此在杂种犬中表现出明显的PCR SSCP多态性     

吸氧预处理对大鼠脑缺血再灌注损伤的保护作用

目的探讨吸氧预处理对大鼠脑缺血再灌注损伤的保护作用。方法通过大鼠局灶脑缺血再灌注损伤模型,采用SOD、MDA测定、电镜及神经行为学检查的方法,观察吸氧预处理对大鼠脑缺血再灌注损伤后SOD、MDA、神经行为学评分及脑组织病理变化。结果吸氧预处理组SOD活力高于对照组(P<0.05),MDA含量、神经行为学评分均低于对照组(P<0.05),脑组织超微结构损伤均减轻。结论吸氧预处理对大鼠脑缺血再灌注损伤有保护作用。     

Linkage disequilibrium between STRPs and SNPs across the human genome

Patterns of linkage disequilibrium (LD) reveal the action of evolutionary processes and provide crucial information for association mapping of disease genes. Although recent studies have described the landscape of LD among single nucleotide polymorphisms (SNPs) from across the human genome, associations involving other classes of molecular variation remain poorly understood. In addition to recombination and population history, mutation rate and process are expected to shape LD. To test this idea, we measured associations between short-tandem-repeat polymorphisms (STRPs), which can mutate rapidly and recurrently, and SNPs in 721 regions across the human genome. We directly compared STRP-SNP LD with SNP-SNP LD from the same genomic regions in the human HapMap populations. The intensity of STRP-SNP LD, measured by the average of D', was reduced, consistent with the action of recurrent mutation. Nevertheless, a higher fraction of STRP-SNP pairs than SNP-SNP pairs showed significant LD, on both short (up to 50 kb) and long (cM) scales. These results reveal the substantial effects of mutational processes on LD at STRPs and provide important measures of the potential of STRPs for association mapping of disease genes.     

羊草草地生长季放牧山羊采食量和食性选择

在松嫩平原羊草草地,通过控制放牧实验对山羊的时限采食量和食性选择进行了研究。结果表明：（1）5－9月份,山羊的时限（1h）采食量平均为0.42kg干物质,其季节动态为5月份最低,随季节推移不断增大,8月份达到最大,9月份又有所减小;时限采食量基本上随放牧率减小而增大,但在最低放牧率小区有所减小。（2）山羊的食性选择随季节推移和放牧率不同而变化。（3）山羊对20－25cm高度草层的选择性最高;各高度草层的食性选择指数随季节推移和放牧率不同而变化;山羊对不同植物的高度选择性存在差异,但高度选择指数的最大值都在15－30cm范围内。