DNA甲基转移酶的表达调控及主要生物学功能

DNA甲基化是表观遗传学的重要部分, 同组蛋白修饰相互作用, 通过改变染色质结构, 调控基因表达。在哺乳类细胞或人体细胞中, DNA甲基化与细胞的增殖、衰老、癌变等生命现象有着重大关系。对催化DNA甲基化的DNA甲基转移酶(DNA methyltransferase, Dnmt)的研究可以揭示DNA甲基化对基因表达调控的机制, 从而研究与之相关的重要生命活动。文章以DNA甲基转移酶作为切入点, 探讨DNA甲基转移酶在基因表达调控中发挥的作用及其主要生物学功能。     

中红侧沟茧蜂化学感受蛋白MmedCSP1的结合特征

化学感受蛋白是一类存在于昆虫化学感受器中的可溶性蛋白, 被认为与昆虫识别外界化学信息有关。本研究使用pGEX-4T-1表达载体在BL21 (DE3)异源表达系统中表达中红侧沟茧蜂Microplitis mediator化学感受蛋白MmedCSP1, 并通过亲和层析法纯化得到去表达标签的MmedCSP1;使用bis-ANS作为荧光配基, 在荧光分光光度计上研究它与50种气味标样的结合特征, 从而得到此类化学感受蛋白在中红侧沟茧蜂嗅觉识别中识别气味的种类。结果表明: MmedCSP1只能与水杨酸甲酯、戊烷、罗勒烯、β-紫罗兰酮、3, 4-二甲基苯甲醛、2-己酮和叶醇结合。但只有脂类化合物β-紫罗兰酮能在浓度为1 mmol/L下将bis-ANS从MmedCSP1中替换50%, β-紫罗兰酮与MmedCSP1的结合常数为16.89 μmol/L。这些结果提示MmedCSP1参与中红侧沟茧蜂对水杨酸甲酯、戊烷、罗勒烯、β-紫罗兰酮、3, 4-二甲基苯甲醛、2-己酮和叶醇等气味的识别过程, 且在不同气味中的识别过程中对于气味的运输能力有差异。     

The significance of CD14+ monocytes in peripheral blood stem cells for the treatment of rat liver cirrhosis

Background aimsCirculating monocytes have been exploited as an important progenitor cell resource for hepatocytes in vitro and are instrumental in the removal of fibrosis. We investigated the significance of monocytes in peripheral blood stem cells (PBSC) for the treatment of liver cirrhosis.MethodsRat CD14⁺ monocytes in PBSC were mobilized with granulocyte-colony-stimulating factor (G-CSF) and harvested by magnetic cell sorting (MACS). Female rats with carbon tetrachloride (CCl₄)-induced liver cirrhosis were injected CM-DiI-labeled monocytes, CD14^? cells (1 × 10⁷ cells/rat) or saline via the portal vein.ResultsRat CD14⁺ and CD11b⁺ monocytes in PBSC were partly positive for CD34, CD45, CD44, Oct3/4 and Sox2, suggesting monocytes with progenitor capacity. Compared with CD14^? cell-infused and saline-injected rats, rats undergoing monocyte transplantation showed a gradually increased serum albumin level and decreased portal vein pressure, resulting in a significantly improved survival rate. Meanwhile, monocyte transplantation apparently attenuated liver fibrosis by analysis for fibronectin, α2-(1)-procollagen, α-smooth muscle aorta (SMA) and transforming growth factor (TGF)-β. Transplanted monocytes mainly clustered in periportal areas of liver, in which 1.8% cells expressed hepatocyte marker albumin and CK18. The expression level of hepatocyte growth factor (HGF), TGF-α, extracellular matrix (EGF) and vascular endothelial growth factor (VEGF) increased, while monocyte transplantation enhanced hepatocyte proliferation. On the other hand, the activities and expression of matrix metalloproteinases (MMP) increased while tissue inhibitor of metalloproteinase (TIMP)-1 expression significantly reduced in monocyte-transplanted livers. Some transplanted monocytes expressed MMP-9 and -13.ConclusionsThe data suggest that CD14⁺ monocytes in PBSC contribute to hepatocyte regeneration and extracellular matrix (ECM) remodeling in rat liver cirrhosis much more than CD14^? cells, and might offer a therapeutic alternative for patients with liver cirrhosis.     

Testing four proposed barcoding markers for the identification of species within Ligustrum L. (Oleaceae)

DNA barcoding is a biological technique that uses short and standardized genes or DNA regions to facilitate species identification. DNA barcoding has been used successfully in several animal and plant groups. Ligustrum (Oleaceae) species occur widely throughout the world and are used as medicinal plants in China. Therefore, the accurate identification of species in this genus is necessary. Four potential DNA barcodes, namely the nuclear ribosomal internal transcribed spacer (ITS) and three chloroplast (cp) DNA regions (rbcL, matK, and trnH–psbA), were used to differentiate species within Ligustrum. BLAST, character-based method, tree-based methods and TAXONDNA analysis were used to investigate the molecular identification capabilities of the chosen markers for discriminating 92 samples representing 20 species of this genus. The results showed that the ITS sequences have the most variable information, followed by trnH–psbA, matK, and rbcL. All sequences of the four regions correctly identified the species at the genus level using BLAST alignment. At the species level, the discriminating power of rbcL, matK, trnH–psbA, and ITS based on neighbor-joining (NJ) trees was 36.8%, 38.9%, 77.8%, and 80%, respectively. Using character-based and maximum parsimony (MP) tree methods together, the discriminating ability of trnH–psbA increased to 88.9%. All species could be differentiated using ITS when combining the NJ tree method with character-based or MP tree methods. Overall, the results indicate that DNA barcoding is an effective molecular identification method for Ligustrum species. We propose the nuclear ribosomal ITS as a plant barcode for plant identification and trnH–psbA as a candidate barcode sequence.     

生物多样性监测指标体系构建研究进展

生物多样性监测是为确定与预期标准相一致或相背离的程度,而对生物多样性进行定期或不定期的监视,目前已成为生物多样性研究和保护的热点问题。生物多样性监测指标则是一些简化的生物或环境特征参数,说明生物多样性现状和变化趋势,以及人类活动压力对生物多样性的影响,以促进科学界、政府和公众间的沟通,提高生物多样性管理水平。近10年来,国际组织、政府机构和各国学者对生物多样性指标体系的构建进行了大量的探索工作,取得了很多进展,其中有些指标已经应用于实际监测项目。本文综述了生物多样性监测指标筛选的一般标准和指标体系构建的主要理论,梳理目前已提出或应用的主要生物多样性监测指标,以期为我国构建国家或区域尺度生物多样性监测指标体系提供参考。在此基础上分析提出：生物多样性概念的泛化、指标含义模糊以及知识和数据的缺乏是构建生物多样性监测指标的主要困难。我国未来的生物多样性监测指标体系构建需要关注以下两个方面：（1）紧密联系实际,构建适应性的监测指标体系,加强对典型生态系统区域的监测;（2）发展经济社会发展方面的指标,分析生物多样性变化的驱动力,为生物多样性保护和区域可持续发展提供科学依据。     

小麦族植物的分类现状及主要存在的问题

小麦族(Triticeae)是禾本科、早熟禾亚科中一个有重要经济价值、以多年生植物占优势的族,族内绝大多数种类是重要的粮食作物和畜牧业上的优良牧草,饲用价值极高,有些种类具有耐寒、耐旱、耐碱等特性,是农牧业上良种繁育、牧草利用的重要基因资源。但该族同时又是分类学上的一个疑难族,各学者对族内系统分类意见不一、争议颇大,尤其在族的界限、族下类群划分以及类群演化关系上问题较多,至今尚未解决。查阅了国内外分类学文献,探讨其分类差异以及存在问题,为充分开发利用中国丰富的小麦族植物资源提供理论依据。     

不同干扰对黄土区典型草原物种多样性和生物量的影响

对黄土区典型草原进行封育+施肥(EF)、封育+火烧(EB)、封育(E)和放牧(G)处理,实地调查分析群落盖度、高度、密度、地上现存量和物种多样性,以研究不同干扰对黄土区典型草原群落物种多样性和生物量的影响.结果表明:在4种干扰类型中,施肥+封育草地群落盖度和地上生物量最高,且优势度指数最高,这与禾本科草占优势地位有关,群落均匀度指数和多样性指数最低,符合“生态位理论”;放牧地群落高度、盖度、密度和地上现存量最低,群落丰富度指数和多样性指数最高,支持“中度干扰理论”;封育地密度和均匀度指数最高;具体表现为:4种干扰类型地上生物量的变化趋势为封育+施肥＞封育+火烧＞封育＞放牧;说明长时间的封育对草地是一种严重干扰.群落丰富度指数(R和Ma)的排列顺序为放牧＞封育+施肥＞封育+火烧＞封育,群落物种多样性指数(H'和D)的排列顺序为放牧＞封育＞封育+火烧＞封育+施肥,优势度指数与多样性指数相反,群落均匀度指数(Jsw和Ea)的排列顺序为封育＞放牧＞封育+火烧＞封育+施肥.不同干扰样地群落生产力与Shannon-Wiener和Simpson 多样性指数间呈负相关关系,这个结论可以用地上/地下竞争的相互作用来解释.     

蝴蝶果茎枝化学成分的研究

从蝴蝶果(Cleidiocarpon cavalerie)茎枝的乙醇提取物中提取并鉴定了7个化合物,利用现代波谱技术(MS、1H-NMR、13C-NMR)进行结构鉴定,结果表明,它们分别为kauran-16-ol-3-one(1)、16β,17-dihydroxy-3-oxo-phyllocladane(2)、kauranoic acid(3)、山萘酚(4)、没食子酸(5)、β-谷甾醇(6)和胡萝卜苷(7)。化合物1~7均为首次从该属植物中获得。     

旺长期遮光及光照转换对不同肥料条件下烟草叶片光合特性的影响

采用盆栽方法研究了旺长期遮光及光照转换对不同肥料条件下烟草叶片光合速率(Pn)与荧光特性的影响。结果表明,遮光促进两种肥料条件下烟草叶片叶绿素(Chl)和类胡萝卜素(Car)含量的积累,却降低它们的Pn。其中施无机肥的烟草叶片Chl含量增加较多,而50%无机肥+50%饼肥配施烟草叶片的Car增幅显著,从而,施无机肥烟草叶片Chl/Car上升,而无机肥+饼肥配施烟草叶片Chl/Car却下降。无论从自然光转至遮荫条件下还是从遮荫条件转至自然光下,两种肥料条件下生长的烟草叶片的Pn、实际光化学效率(ΦPSⅡ)、最大光化学效率(Fv/Fm)及光化学猝灭系数(qP)均急剧下降,但与施无机肥相比,无机肥+饼肥配施烟草叶片保持较高的Pn、ΦPSⅡ、Fv/Fm、及qP,可能是饼肥促进了栽培条件下烟草植株的光生态适应性。     

黄麻吸附重金属Cr(Ⅵ)专用种质筛选

首次以国内外23个代表性黄麻种质为研究对象,用主茎嫩梢和一、二级分枝嫩梢制成天然重金属吸附剂,测定其对溶液中Cr(Ⅵ)离子的去除率,并对与黄麻吸附能力及产量密切相关的功能性状:生育期动态、株高、分枝习性、各级分枝嫩梢的产量进行调查、方差分析和相关性分析。结果表明,不同黄麻种质制成的生物吸附剂对Cr(Ⅵ)的吸附能力不同,去除率在85.25%~96.88%之间;不同级次分枝嫩梢的产量及对Cr(Ⅵ)的去除率不同;种质间除出苗速度外所有调查性状均存在较大差异;去除率与株高呈极显著负相关(P<0.01)。从产量和去除率方面综合考虑,J001和J011 2个种质表现优良,适宜作为吸附重金属专用品种推广种植。