分子生物学技术在热泉地质微生物学研究中的应用

陆地热泉是一类典型的极端生命-环境互作的地质系统,是我们认识生命与环境协同演化的天然实验室。然而,受限于有限的研究手段,热泉中仍存在大量未解密的微生物"暗物质"。这种困境随着技术的革新得到了改善,尤其是近几年来基于组学、探针和同位素标记的多元化检测手段在嗜热微生物多样性的挖掘、新物种和新代谢途径的发现以及嗜热微生物对元素地球化学循环的调控和响应等方面取得了一系列令人瞩目的研究成果,使得热泉极端微生物和地质环境内在联系的研究也成为地质微生物学研究的热点。立足于前人研究成果,本文将简述常用于热泉地质微生物学研究的分子生物学手段的发展,重点总结其在挖掘热泉微生物多样性和热泉微生物的环境功能研究中的应用及进展,最后对未来研究方向提出展望。     

基于多元回归树的公益林群落结构解析

为揭示不同生境类型下公益林群落物种多样性及优势种种间关系特征, 以临安市公益林125个固定监测样地为研究对象, 利用多元回归树(MRT)进行群落分类, 以物种多样性指数和种间联结系数为指标, 对不同群落类型的结构特征进行探索。结果表明: 临安市公益林125个典型样地可划分为5个类型; 类型I、II、III与类型V的多样性指数之间均无显著差异, 但类型III的多样性指数均最高, 类型IV的物种多样性指数均显著低于其它类型, 海拔是影响群落多样性水平的主要因子。种间联结初步分析显示, 研究区群落中稳定性最高的层片是乔木层, 且毛竹入侵极可能是影响5个类型植物群落稳定性的关键因素。研究结果可为临安市公益林分类经营管理提供理论依据, 同时为区域公益林群落数量结构研究奠定基础。     

茶园害虫匮乏期天敌与蚊虫的空间关系

为了充分发挥中性昆虫蚊虫作为天敌的食饵替代物作用,科学地保护和利用自然天敌,2015年和2016年开展了合肥地区白毫早茶园和乌牛早茶园害虫匮乏时期(3—5月)的天敌与蚊虫之间的空间关系研究,运用地学统计学方法求得天敌和蚊虫各自的变程,用灰色关联度方法分析蚊虫与天敌变程的关联度,关联度值越大的天敌在空间上对蚊虫的跟随关系越密切。并分析茶树品种间及年度间天敌位次的变化。8种天敌中,白毫早茶园2015年与蚊虫空间跟随关系密切的前四位天敌是粽管巢蛛、八斑球腹蛛、三突花蟹蛛和茶色新圆蛛;2016年的是粽管巢蛛、茶色新圆蛛、锥腹肖蛸和三突花蟹蛛;两年间前四位天敌有3种相同,但位次不全相同。乌牛早茶园2015年与蚊虫空间跟随关系密切的前四位天敌是八斑球腹蛛、茶色新圆蛛、锥腹肖蛸和三突花蟹蛛;2016年的是三突花蟹蛛、粽管巢蛛、草间小黑蛛和茶色新圆蛛;两年间前四位天敌中有茶色新圆蛛和三突花蟹蛛2种相同。年度间天敌位次相异率为87.5%,茶树品种间天敌位次相异率为93.75%。按照天敌位次总和及按照天敌与蚊虫空间关系密切指数总和评判,两种茶园2015年和2016年3—5月份与蚊虫空间关系密切的前四位天敌均依次是粽管巢蛛、三突花蟹蛛、茶色新圆蛛和八斑球腹蛛。本文的结果为人为地促进优势种天敌建群,合理保护和利用自然天敌提供科学依据。     

Differentiation of embryonic stem cell to astrocytes visualized by green fluorescent protein

Green fluorescent protein (GFP) gene was transfected and expressed in murine embryonic stem (ES) cells under the control of the astrocyte-specific glial fibrillary acidic protein (GFAP) promoter. Stably transfected cells were characterized by immunohistochemistry and by fluorescence microscopy. Cells containing GFP were differentiated to Type I and Type II astrocytes after induction by all-trans retinoic acid. Differentiated cells were expressed GFP and visualized by fluorescence microscopy. Differentiated cells expressed GFP were correlated with the expression of GFAP and morphological change. It demonstrates that the cell line expressed GFP can be used to trace the morphological changes of astrocytes during differentiation, and further for the isolation of astrocytes from the mixed cells differentiated from ES cell.     

Cancer-initiating cells derived from human rectal adenocarcinoma tissues carry mesenchymal phenotypes and resist drug therapies

Accumulating evidence indicates that cancer-initiating cells (CICs) are responsible for cancer initiation, relapse, and metastasis. Colorectal carcinoma (CRC) is typically classified into proximal colon, distal colon, and rectal cancer. The gradual changes in CRC molecular features within the bowel may have considerable implications in colon and rectal CICs. Unfortunately, limited information is available on CICs derived from rectal cancer, although colon CICs have been described. Here we identified rectal CICs (R-CICs) that possess differentiation potential in tumors derived from patients with rectal adenocarcinoma. The R-CICs carried both CD44 and CD54 surface markers, while R-CICs and their immediate progenies carried potential epithelial–mesenchymal transition characteristics. These R-CICs generated tumors similar to their tumor of origin when injected into immunodeficient mice, differentiated into rectal epithelial cells in vitro, and were capable of self-renewal both in vitro and in vivo. More importantly, subpopulations of R-CICs resisted both 5-fluorouracil/calcium folinate/oxaliplatin (FolFox) and cetuximab treatment, which are the most common therapeutic regimens used for patients with advanced or metastatic rectal cancer. Thus, the identification, expansion, and properties of R-CICs provide an ideal cellular model to further investigate tumor progression and determine therapeutic resistance in these patients.     

mem-iLID,a fast and economic protein purification method

Protein purification is the vital basis to study the function, structure and interaction of proteins. Widely used methods are affinity chromatography-based purifications, which require different chromatography columns and harsh conditions, such as acidic pH and/or adding imidazole or high salt concentration, to elute and collect the purified proteins. Here we established an easy and fast purification method for soluble proteins under mild conditions, based on the light-induced protein dimerization system improved light-induced dimer (iLID), which regulates protein binding and release with light. We utilize the biological membrane, which can be easily separated by centrifugation, as the port to anchor the target proteins. In Xenopus laevis oocyte and Escherichia coli, the blue light-sensitive part of iLID, AsLOV2-SsrA, was targeted to the plasma membrane by different membrane anchors. The other part of iLID, SspB, was fused with the protein of interest (POI) and expressed in the cytosol. The SspB-POI can be captured to the membrane fraction through light-induced binding to AsLOV2-SsrA and then released purely to fresh buffer in the dark after simple centrifugation and washing. This method, named mem-iLID, is very flexible in scale and economic. We demonstrate the quickly obtained yield of two pure and fully functional enzymes: a DNA polymerase and a light-activated adenylyl cyclase. Furthermore, we also designed a new SspB mutant for better dissociation and less interference with the POI, which could potentially facilitate other optogenetic manipulations of protein–protein interaction.     

丹桂和籽银桂花芽分化的研究

采用石蜡切片技术, 对不育的丹桂(Osmanthus fragrans ‘Dangui’ )和可育的籽银桂(Osmanthus fragrans ‘Ziyingui’)花芽分化的过程进行了研究。结果表明, 桂花(Osmanthus fragrans Lour.)花芽形态分化可分为花芽分化初始期、总苞分化期、花原基分化期、顶花花被分化期、雄蕊分化期和雌蕊分化期6个阶段。雄蕊的发育在丹桂和籽银桂之间基本没有区别, 都能形成完整的花粉囊和成熟的花粉粒。但是, 雌蕊的发育在可育的籽银桂与不育的丹桂之间存在明显差异。根据花芽分化的过程证明, 丹桂的不育是由于雌蕊发育不正常导致的。     

In vitro and in vivo antioxidant activity of exopolysaccharide fractions from Bifidobacterium animalis RH

The aim of the study was to purify the exopolysaccharides (EPS) produced from Bifidobacterium animalis RH, which was isolated from the feces of Bama centenarians in Guangxi of China, and evaluate their antioxidant activities in vitro and in vivo. 2 fractions, a neutral EPS fraction (EPSa) and an acidic EPS fraction (EPSb), were obtained and compared for antioxidative activity. In vitro, they both showed remarkable inhibition effect on lipid peroxidation and strong DPPH radical scavenging activity, hydroxyl radical scavenging activity, superoxide radical scavenging activity, in which the last two were measured by the electron spin resonance (ESR). In vivo, EPSa and EPSb were orally administrated for 30 days in a d-galactose induced aged mice model. As results, they both could significantly increase the activities of SOD, CAT and total antioxidant capacity (TAOC) in serums and glutathione GST in livers. They also could inhibit significantly the formation of MDA in serums and livers, and reduce the activity of MAO and lipofuscin accumulation in mice brain. Moreover, EPSb exhibited much higher antioxidant activities than EPSa in vitro and in vivo. The results suggested that EPS fractions of Bifidobacterium animalis RH had direct and potent antioxidant activities.