Molecular genetic relationships of the extinct dusky seaside sparrow

Mitochondrial DNA from the extinct dusky seaside sparrow (Ammodramus maritimus nigrescens) was compared in terms of nucleotide sequence divergence to mitochondrial DNAs from extant populations of seaside sparrows. Analyses of restriction sites revealed a close phylogenetic affinity of A. m. nigrescens to other sparrow populations along the Atlantic coast of the United States but considerable genetic distance from Gulf coast birds. Concerns and applied management strategies for the seaside sparrow have been based on a morphological taxonomy that does not adequately reflect evolutionary relationships within the complex.     

大肠息肉癌变的内镜诊断及病理分析

目的：分析大肠息肉癌变的分布、大小、形态、病理特征及寻求息肉癌变的早期诊断、防治的方法。方法：回顾性分析经内镜诊断的68例（71个）大肠息内癌变的内镜、病理与临床资料。结果：1660例（2540个）大肠息肉中有68例（71个）癌变，癌变率为4．10％，左半结肠息肉癌变69个，占息肉癌变总数的97.18%。绒毛状腺瘤、混合腺瘤癌变率较高（分别为56．76％、14．71％），管状腺瘤癌变率较低（为4．17％）。息肉直径＞2.0cm者癌变率为37.40%，息肉直径1.0-2.0cm者癌变率为4.64%，息肉直径＜1cm者癌变率为0.43%，息肉直径＞2.0cm者癌变率明显高于2.0cm以下者。广基息肉癌变率10.08%。结论：左半结肠息肉、宽基息肉、直径＞2.0cm息肉、绒毛状腺瘤容易癌变。大肠息肉不论大小应尽可能予以切除，全瘤送检。内镜切除大肠息肉可预防息肉癌变。     

Successful transmission of a retrovirus depends on the commensal microbiota

To establish chronic infections, viruses must develop strategies to evade the host's immune responses. Many retroviruses, including mouse mammary tumor virus (MMTV), are transmitted most efficiently through mucosal surfaces rich in microbiota. We found that MMTV, when ingested by newborn mice, stimulates a state of unresponsiveness toward viral antigens. This process required the intestinal microbiota, as antibiotic-treated mice or germ-free mice did not transmit infectious virus to their offspring. MMTV-bound bacterial lipopolysaccharide triggered Toll-like receptor 4 and subsequent interleukin-6 (IL-6)-dependent induction of the inhibitory cytokine IL-10. Thus, MMTV has evolved to rely on the interaction with the microbiota to induce an immune evasion pathway. Together, these findings reveal the fundamental importance of commensal microbiota in viral infections.     

Molecular analysis of plant migration and refugia in the Arctic

The arctic flora is thought to have originated during the late Tertiary, approximately 3 million years ago. Plant migration routes during colonization of the Arctic are currently unknown, and uncertainty remains over where arctic plants survived Pleistocene glaciations. A phylogenetic analysis of chloroplast DNA variation in the purple saxifrage (Saxifraga oppositifolia) indicates that this plant first occurred in the Arctic in western Beringia before it migrated east and west to achieve a circumpolar distribution. The geographical distribution of chloroplast DNA variation in the species supports the hypothesis that, during Pleistocene glaciations, some plant refugia were located in the Arctic as well as at more southern latitudes.     

Molecular analysis of protein assembly in muscle development

The challenge presented by myofibril assembly in striated muscle is to understand the molecular mechanisms by which its protein components are arranged at each level of organization. Recent advances in the genetics and cell biology of muscle development have shown that in vivo assembly of the myofilaments requires a complex array of structural and associated proteins and that organization of whole sarcomeres occurs initially at the cell membrane. These studies have been complemented by in vitro analyses of the renaturation, polymerization, and three-dimensional structure of the purified proteins.     

山药原植物薯蓣及其近缘种的分子鉴别和亲缘关系研究

采用CTAB法提取总DNA,应用PCR产物直接测序法,测定了山药原植物薯蓣及其近缘种共10个种和1个变种的trnL-F和rbcL序列.序列分析结果表明:薯蓣及其近缘种trnL-F序列长689～834 bp,当空位始终作缺失处理时,有变异位点67个,其中信息位点11个,占序列总长度的1.43%;种间碱基差异百分率为1.6%,其中转换率为0.6%,颠换率为1.0%;序列的G C含量为32.5%.薯蓣及其近缘种rbcL序列长1 096～1 160 bp,存在变异位点42个,其中信息位点10个,占序列总长度的0.93%;种间碱基差异百分率为0.6%,其中转换率为0.3%,颠换率为0.3%;序列G C含量为44.1%.基于2个序列分别重建了薯蓣及其近缘种的系统发育树.结果表明2个系统树的结构基本一致,均支持经典分类方法对薯蓣及其近缘种的亲缘关系的划分.同时,本研究也证实叶绿体基因组序列测定是鉴定山药原植物薯蓣及其近缘种的快速、可靠、有效的方法.     

Molecular analysis of the hotspot of recombination in the murine major histocompatibility complex

Biological and serological assays have been used to define four subregions for the I region of the major histocompatibility complex (MHC) in the order I-A, I-B, I-J, and I-E. The I-J subregion presumably encodes the I-J polypeptide of the elusive T-cell suppressor factors. Restriction enzyme site polymorphisms and DNA sequence analyses of the I region from four recombinant mouse strains were used to localize the putative I-B and I-J subregions to a 1.0-kilobase (kb) region within the E beta gene. Sequencing this region from E beta clones derived from the two mouse strains: B10.A(3R), I-Jb and B10.A(5R), I-Jk initially used to define the I-J subregion revealed that these regions are identical, hence the distinct I-Jb and I-Jk molecules cannot be encoded by this DNA. In addition, the DNA sequence data also refute the earlier mapping of the I-B subregion. Analysis of the DNA sequences of three parental and four I region recombinants reveals that the recombinant events in three of the recombinant strains occurred within a 1-kb region of DNA, supporting the proposition that a hotspot for recombination exists in the I region. The only striking feature of this hotspot is a tetramer repeat (AGGC)n that shows 80 percent homology to the minisatellite sequence which may facilitate recombination in human chromosomes.     

Host-bacterial mutualism in the human intestine

The distal human intestine represents an anaerobic bioreactor programmed with an enormous population of bacteria, dominated by relatively few divisions that are highly diverse at the strain/subspecies level. This microbiota and its collective genomes (microbiome) provide us with genetic and metabolic attributes we have not been required to evolve on our own, including the ability to harvest otherwise inaccessible nutrients. New studies are revealing how the gut microbiota has coevolved with us and how it manipulates and complements our biology in ways that are mutually beneficial. We are also starting to understand how certain keystone members of the microbiota operate to maintain the stability and functional adaptability of this microbial organ.     

我国几种松干锈菌亲缘关系的ITS序列分析

首次对我国松干锈菌的核糖体DNA中的内转录间隔区(ITS)序列进行了测定,并与得到普遍承认的国外柱锈菌属其它种的ITS进行了比较.运用PAUP和TREECON软件进行系统发育分析并得到了一致的结果:我国Cronartium flaccidum 和C.quercuum的菌株各自分别形成一个分支,而C.ribicola按锈孢子寄主分成了红松和华山松两个分支, 红松上和华山松上的C.ribicola相互间遗传距离很大,分别和其它的种平行,该结果显示了原来被鉴定为C.ribicola的我国特有的华山松疱锈菌,可能是一个不同于C.ribicola的独立的种.     

Molecular analysis by mass spectrometry

New ionization methods combined with powerful analyzers, detectors, and data systems have made mass spectrometry a versatile tool for molecular analysis. Samples consisting of nanogram quantities of hundreds of unique components are routinely analyzed. In favorable cases samples as small as 2.5 x 10(-14) gram and samples with masses of more than 3000 atomic mass units have been successfully examined.     

遗传多样性研究进展

目的从表型和分子标记两个角度对厚叶栒子野生种群开展研究,旨在揭示其遗传多样性。方法利用31个表型性状和30条ISSR引物对滇产野生厚叶栒子居群进行遗传多样性分析,用PopGen 32软件计算多样性指数,用SPSS 16.0软件构建系统发育树系图。结果厚叶栒子居群间表型性状差异较小;30条ISSR引物扩增出282条带,其中231条具有多态性,平均多态率为81.91%,Nei’s基因多样性指数和香农多样性指数分别为0.414 1和0.597 9。采用UPGMA法构建的形态和分子标记两种树系图基本一致,分布在同一区域的各个居群多数能聚在一起,地理位置的隔离促进了厚叶栒子居群间的遗传分化;个别居群未能与同一区域的其他居群聚在一起,其原因可能是同一区域内各居群的小生境不完全相同,而不同区域间也有相似的小生境,导致厚叶栒子居群间发生了趋同进化。结论滇产野生厚叶栒子具有丰富的遗传多样性,研究结果为厚叶栒子种质资源的开发利用提供了科学依据。     

白斑综合征病毒与凡纳滨对虾肠道菌群区系之间关系的初步研究

比较了同一养殖池中的感染白斑综合征病毒(WSSV)和未感染WSSV的凡纳滨对虾的肠道菌群,旨在探讨对虾肠道菌群与机体健康状态之间的关系。感染WSSV对虾肠道的细菌总数为1.06×106CFU/尾,显著高于未感染WSSV的对虾(1.78×105CFU/尾;P<0.05),且其肠道中的细菌分别属于弧菌属、气单胞菌属、海水球菌属、盐水球菌属和乳酸杆菌属;染WSSV的对虾(P<0.05),气单胞菌的比例显著的低于感染WSSV的对虾(P<0.05);盐球菌所占的比例两者之间差异不显著。结果显示,两种对虾在肠道菌群组成和细菌组成和细菌数量上存在显著的差异,初步表明对虾肠道菌群区系和机体的健康状态密切相关。     

白斑综合征病毒与凡纳滨对虾肠道菌群区系之间关系的初步研究

比较了同一养殖池中的感染白斑综合征病毒(WSSV)和未感染WSSV的凡纳滨对虾的肠道菌群,旨在探讨对虾肠道菌群与机体健康状态之间的关系。感染WSSV对虾肠道的细菌总数为1.06×106CFU/尾,显著高于未感染WSSV的对虾(1.78×105CFU/尾;P<0.05),且其肠道中的细菌分别属于弧菌属、气单胞菌属、海水球菌属、盐水球菌属和乳酸杆菌属;染WSSV的对虾(P<0.05),气单胞菌的比例显著的低于感染WSSV的对虾(P<0.05);盐球菌所占的比例两者之间差异不显著。结果显示,两种对虾在肠道菌群组成和细菌组成和细菌数量上存在显著的差异,初步表明对虾肠道菌群区系和机体的健康状态密切相关。     

Solar-climate relationships in the post-pleistocene

The most conspicuous climatic aberration of the past two millennia was the temperature decline and glacial advance of the A.D. 1550 to 1900 period. This temperature decline has been correlated with an interval of lower solar activity and there is evidence from both the post-Pleistocene glacial record and from oxygen-18 analysis that such an interval han recurred at cyclic periods of around 2400 to 2600 years.     

Innate lymphoid cells promote anatomical containment of lymphoid-resident commensal bacteria

The mammalian intestinal tract is colonized by trillions of beneficial commensal bacteria that are anatomically restricted to specific niches. However, the mechanisms that regulate anatomical containment remain unclear. Here, we show that interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) are present in intestinal tissues of healthy mammals. Depletion of ILCs resulted in peripheral dissemination of commensal bacteria and systemic inflammation, which was prevented by administration of IL-22. Disseminating bacteria were identified as Alcaligenes species originating from host lymphoid tissues. Alcaligenes was sufficient to promote systemic inflammation after ILC depletion in mice, and Alcaligenes-specific systemic immune responses were associated with Crohn's disease and progressive hepatitis C virus infection in patients. Collectively, these data indicate that ILCs regulate selective containment of lymphoid-resident bacteria to prevent systemic inflammation associated with chronic diseases.     

42个甜(辣)椒自交系恢复基因的分布及亲缘关系的RAPD分析

以42个甜(辣)椒自交系和甜椒胞质雄性不育系CMST6A与CMSMCA为试材,对其测交后代的育性进行了鉴定分析.结果表明:育性恢复材料占全部被测材料的31.0%,育性保持材料占66.7%,育性分离材料占2.3%.甜椒CMS育性恢复基因主要存在于尖辣椒中.利用RAPD技术,进一步分析了这些自交系的DNA多态性.从340条随机引物中筛选出扩增效果良好的引物23条,共扩增出133条谱带,其中多态性带111条.UPGMA树状图显示,遗传距离为0.124时可以将42个甜(辣)椒自交系划分为3组,育性恢复辣椒在Ⅰ、Ⅱ和Ⅲ组内均有分布,说明在分子水平上恢复基因在供试辣椒自交系中的分布是随机的.     

10个佛手瓜栽培品种亲缘关系的SRAP分析

研究影响佛手瓜SRAP扩增反应的主要因子,建立佛手瓜SRAP反应的优化体系,利用SRAP技术对福建省10个佛手瓜栽培种进行亲缘关系分析.筛选出10对具有较高扩增多态性的引物组合,共扩增出条带114条,其中62条为多态性条带,多态率为54.38%.聚类分析结果表明,当遗传距离为0.20时,可将10个品种分为3个类群;遗传距离为0.35时,10个品种聚为一类,表明10个佛手瓜品种的亲缘关系较近.     

克氏原螯虾PcDsx基因的克隆及表达分析

为阐明克氏原螯虾(Procambarus clarkii) doublesex(PcDsx)的功能,采用RACE技术克隆获得PcDsx cDNA序列,利用qRT-PCR检测该基因的表达情况。生物信息学分析结果显示,该基因cDNA全长1 584 bp,包括243 bp 5′UTR、765 bp ORF(编码254 aa)和576 bp 3′UTR;PcDsx蛋白包含1个保守的DM结构域,与东方刺龙虾(Sagmariasus verreauxi)SvDsx的DM结构域相似性较高。基因表达分析结果显示,PcDsx广泛表达于成年克氏原螯虾的各组织中,其中克氏原螯虾触角腺中该基因的相对表达量最高,性腺和肌肉中的相对表达量也较高,并且发现该基因在成年雌虾多种组织中的表达与相应雄虾组织中的表达存在显著性差异;克氏原螯虾早期发育不同时期表达分析结果表明,PcDsx的表达水平在出膜后3 d达到一个高峰,而幼虾中PcDsx的最高表达分别出现在出膜后41 d和115 d,此外,该基因在出膜后期雌雄幼虾中的表达亦表现出显著性差异。