Small RNAs derived from snoRNAs

Small nucleolar RNAs (snoRNAs) guide RNA modification and are localized in nucleoli and Cajal bodies in eukaryotic cells. Components of the RNA silencing pathway associate with these structures, and two recent reports have revealed that a human and a protozoan snoRNA can be processed into miRNA-like RNAs. Here we show that small RNAs with evolutionary conservation of size and position are derived from the vast majority of snoRNA loci in animals (human, mouse, chicken, fruit fly), Arabidopsis, and fission yeast. In animals, sno-derived RNAs (sdRNAs) from H/ACA snoRNAs are predominantly 20–24 nucleotides (nt) in length and originate from the 3′ end. Those derived from C/D snoRNAs show a bimodal size distribution at ∼17–19 nt and >27 nt and predominantly originate from the 5′ end. SdRNAs are associated with AGO7 in Arabidopsis and Ago1 in fission yeast with characteristic 5′ nucleotide biases and show altered expression patterns in fly loquacious and Dicer-2 and mouse Dicer1 and Dgcr8 mutants. These findings indicate that there is interplay between the RNA silencing and snoRNA-mediated RNA processing systems, and that sdRNAs comprise a novel and ancient class of small RNAs in eukaryotes.     

植物信号系统--它在功能整合与适应环境中的作用

高等植物是由多层次结构（细胞、组织、器官）组成，在多变环境下生活的开放系统。各部位的处境不同，分工各异。因而它们之间必需通过信号传递进行信息交换才能协调整株的行为、适应外界的变化。植物信号具有多种形式，如化学信号、电波信号与水力信号等。本文主要以乙酰胆碱在信号传递中的功能为例证阐述植物的信号系统。     

Small RNAs in Human Brain Development and Disorders

Small RNA is a variable and abundant type of non-coding RNAs in brain. The function of these RNAs is mainly unknown. A specific class of small RNA, microRNA, is dynamically regulated in neurogenesis and in embryo brain development. The genes for synaptic formation and some mental retardation disorders are putative targets for microRNA predicted by computational algorithms. The molecular pathways for mental development, common forms of autisms, schizophrenia, and affective disorders have yet to be elucidated. The hypothesis proposed here is that small regulatory RNAs, specifically microRNAs, play a role in human brain development and pathogenesis of brain disorders, especially of neurodevelopmental conditions. Pilot tests using comprehensive arrays of microRNAs demonstrate that microRNAs derived from postmortem human brains are applicable for microRNA expression profiling. The abundant expression of many regulatory small RNAs in human brain implies their biological role that must be tested by functional assays in neurons and by genetic and comparative expression profiling.     

Assessment of Arsenite,Arsenate, and Chromate Phytotoxicity Based on the Activity of Seed Germination and Growth (Root & Shoot) of Various Plant Seeds

Effects of different concentrations of arsenite, arsenate, and chromate on seed germination, root length (RL), and shoot length (SL) in four seed types, chosen from preliminary tests with eight seed types, were investigated to assess the toxicity of the tested metals. The sensitivities of the four different seed types toward germination, relative RL (RRL), and relative SL (RSL) varied with each metal. In a comparison, the germination of the seeds was more sensitive to the tested metals than the other chosen endpoints (RL and SL). Arsenite was generally more restrictive to all the endpoints (germination, root, and shoot growth) than arsenate and chromate. Lactuca (garden lettuce) was also generally more sensitive to the tested metals than the other seed types. The correlation between RRL and RSL varied depending on the seed type and metal tested. However, significant correlations (r² > 0.85) of these were observed with Lactuca seeds, which appeared to be an optimal plant with respect to the tolerance of the tested metals. The differences in the toxicities of metals toward different plant species should be taken into account in the bioassessment of metals-contaminated sites. Thus, this study encourages the need to combine the three endpoints of various seeds in the evaluation of toxicities of metals.     

福建梁野山国家级自然保护区种子植物区系研究

通过野外调查、采集标本和查阅相关文献资料,编制福建梁野山自然保护区野生种子植物名录,进行植物区系组成和分布区类型的分析,并将其与周边相邻2个保护区的植物区系进行比较。结果表明:(1)梁野山自然保护区共有野生种子植物154科662属1 498种,种类丰富。(2)区系地理成分以热带分布型为主,其中在科级水平上热带分布型所属科共有85科,占总科数的69.67%;在属级水平上热带性质分布型的属有371属,占总属数的60.82%。但相当数量温带成分的存在,体现了亚热带植物区系的特点。(3)对梁野山保护区与周边相邻的武夷山和南靖南亚热带雨林保护区的植物区系比较发现,梁野山种子植物区系属数的热带属数/温带属数(R/T值,1.66)高于武夷山的R/T值(1.10)而低于南靖南亚热带雨林保护区的R/T值(2.68),梁野山种子植物区系与该相邻2个保护区的相似性系数非常接近,但在区系成分上,梁野山既有与武夷山共有而南靖南亚热带雨林保护区没有分布的温带成分,也有与南靖南亚热带雨林保护区共有而武夷山没有的热带成分,说明梁野山植物区系与其地处武夷山脉南端的地理位置相一致,具有明显的从南亚热带向中亚热带过渡的特点。     

Arabinan Metabolism during Seed Development and Germination in Arabidopsis

Arabinans are found in the pectic network of many cell walls, where, along with galactan, they are present as side chains of Rhamnogalacturonan I. Whilst arabinans have been reported to be abundant polymers in the cell walls of seeds from a range of plant species, their proposed role as a storage reserve has not been thoroughly investigated. In the cell walls of Arabidopsis seeds, arabinose accounts for approximately 40% of the monosaccharide composition of non- cellulosic polysaccharides of embryos. Arabinose levels decline to -15% during seedling establishment, indicating that cell wall arabinans may be mobilized during germination. Immunolocalization of arabinan in embryos, seeds, and seedlings reveals that arabinans accumulate in developing and mature embryos, but disappear during germination and seedling establishment. Experiments using 14C-arabinose show that it is readily incorporated and metabolized in growing seedlings, indicating an active catabolic pathway for this sugar. We found that depleting arabinans in seeds using a fungal arabinanase causes delayed seedling growth, lending support to the hypothesis that these polymers may help fuel early seedling growth.     

Plant stem cells and their regulations in shoot apical meristems

Stem cells in plants, established during embryogenesis, are located in the centers of the shoot apical meristem (SAM) and the root apical meristem (RAM). Stem cells in SAM have a capacity to renew themselves and to produce new organs and tissues indefinitely. Although fully differentiated organs such as leaves do not contain stem cells, cells in such organs do have the capacity to re-establish new stem cells, especially under the induction of phytohormones in vitro. Cytokinin and auxin are critical in creating position signals in the SAM to maintain the stem cell organizing center and to position the new organ primordia, respectively. This review addresses the distinct features of plant stem cells and focuses on how stem cell renewal and differentiation are regulated in SAMs.     

马边大风顶国家级自然保护区种子植物区系研究

马边大风顶国家级自然保护区位于四川省马边县境内。在野外考察及查阅文献的基础上,对保护区内种子植物区系进行了研究。结果显示：保护区内有种子植物120科,446属,1240种,其中裸子植物5科,11属,27种;被子植物115科,435属,1213种。保护区区系成分较复杂,古老区系成分和滇藏高原成分较多。种子植物科的分布区类型有11个,具有较强的热带性质,泛热带（热带广布,Pantropic）型34科,占总科数的40．96％,属的分布区类型有15个,以温带区系成分为主,共264属,占总数属的64．71％。相似性系数计算结果显示,其与美姑大风顶自然保护区种子植物区系亲缘关系十分密切,区系组成相当一致,应该属于同一古老区系演化而成。     

植物生长调节剂对降香黄檀种子萌发的影响

用6-BA、IBA、GA 3等3种植物生长调节剂对降香黄檀种子进行萌发处理,测定降香黄檀种子中可溶性糖、淀粉、蛋白质和脂肪含量的变化。结果表明,降香黄檀种子在不同的萌发处理过程中,可溶性糖含量均呈下降趋势,萌发结束时淀粉含量由第3 d的0.6%下降至0.2%以下,其中6-BA处理后种子萌发前期（3～6 d）淀粉含量变化不大,后期则有一个显著的下降趋势;3种植物生长调节剂对降香黄檀种子蛋白质、脂肪含量变化影响不明显。     

川西三大干流水电开发影响区种子植物区系研究

在对川西雅砻江、大渡河和岷江三大干流水电开发影响区种子植物进行调查的基础上,对其区系特征进行了统计分析和比较研究,结果表明:(1)岷江和大渡河影响区裸子植物科、属、种数量多于雅砻江,被子植物属、种数量远少于雅砻江.(2)在科水平上均具有明显热带区系性质;在属水平上显示出热带和暖温带性质,雅砻江影响区热带属的比例高于温带属,岷江和大渡河则相反.(3)中国种子植物属15大分布区类型在岷江影响区均有分布,在雅砻江、大渡河各有1项没有出现.(4)大渡河和岷江影响区优势科属较雅砻江明显.(5)大渡河影响区属的系数"相对最低,区系丰富度较大.(6)岷江影响区特有属最多,雅砻江最少.(7)雅砻江和岷江影响区珍稀濒危及保护物种较大渡河多.     

盐胁迫对4种短命植物种子萌发及植株生长的影响

以新疆北部4种十字花科短命植物为材料,研究不同浓度NaCl胁迫下其种子萌发及植株生长特性,以明确它们的耐盐性强弱。结果显示:(1)随着NaCl浓度的增加,4种植物种子萌发率、萌发指数和相对萌发率均不同程度下降,而相对盐害率则逐渐升高,并以绵果荠的耐盐性最好,其在300 mmol.L-1NaCl胁迫下仍有22.22%的萌发率。(2)4种植物的生长在50~150 mmol.L-1NaCl胁迫下没有受到明显抑制,在200 mmol.L-1浓度下受不同程度的抑制,而在300 mmol.L-1NaCl胁迫下抑制作用更严重,其中绵果荠在各浓度处理下长势均最好,能够在300 mmol.L-1NaCl胁迫下存活10 d。(3)在盐胁迫条件下,4种植物细胞质膜透性不同程度增加,而叶片相对含水量和光合色素含量均不同程度降低,并以绵果荠各项指标的变化幅度最小。可见,4种新疆短命植物种子萌发和植株生长均受到盐胁迫的伤害,但它们的耐盐阈值明显不同,并以绵果荠的耐盐性最强。     

福建省种子植物分布新记录

在福建闽东地区海岛植被调查中,发现了福建省种子植物地理分布新记录属1个:假还阳参属(Crepidiastrum Nakai);新记录种7个,分别是:碱蓬[Suaeda glauca (Bunge) Bunge]、海滨木槿(Hibiscus hamabo Sieb.et Zucc.)、假还阳参[Crepidiastrum lanceolatum (Houtt.) Nakai]、普陀狗哇花(Heteropappus arenarius Kitam.)、浙江大青(Clerodendrum kaichianum P.S.Hsu)、厚叶石斑木[Rhaphiolepis umbellate(Thunb.) Makino]和刺葵(Phoenix hanceana Naudin)。标本全部存放于宁德师专植物标本室(NDTC)。     

小麦成熟胚高频植株再生系统的建立

在研究小麦成熟种子不同预处理时间、不同种类和浓度生长调节物质、分化培养基中是否添加CuSO4、不同外植体类型和不同放置方式对小麦成熟胚愈伤组织诱导和分化的基础上,建立了一套高效、可靠、重复性好的小麦成熟胚高频植株再生系统.以小麦成熟种子完整胚作为外植体的诱导频率为100%;除掉胚的原胚芽部位生长出的芽苗后,转分化的分化频率达到42.50%.     

七种植物籽油中脂肪酸成分的比较分析(英文)

为寻求新的食用油资源,发展了一种快速可靠的气相色谱-质谱联用方法,用于植物籽油中脂肪酸成分的定性鉴定和含量测定。所建立的方法成功用于葡萄籽、南瓜籽和猕猴桃籽等七种植物籽油中的棕榈酸、十八烷酸、油酸、亚油酸和α-亚麻酸的定性定量分析。结果表明,刺葡萄籽油、普通葡萄籽油、国外葡萄籽油、南瓜籽油、枸杞籽油和西番莲籽油均具有相似的脂肪酸谱,尽管其中它们所含上述五种脂肪酸含量不同,由于均存在人体所必需的饱和与不饱和脂肪酸,故可以用作替代食用油。猕猴桃籽油因为其存在高含量的α-亚麻酸成分,可能是更好的食用油和营养油资源。本文首次对枸杞籽油、西番莲籽油和猕猴桃籽油脂肪酸成分进行绝对含量分析,为新的食用油资源的开发提供了重要的依据。     

Small regulatory RNAs controlled by genomic imprinting and their contribution to human disease

More than a hundred protein-coding genes are controlled by genomic imprinting in humans. These atypical genes are organized in chromosomal domains, each of which is controlled by a differentially methylated "imprinting control region" (ICR). How ICRs mediate the parental allele-specific expression of close-by genes is now becoming understood. At several imprinted domains, this epigenetic mechanism involves the action of long non-coding RNAs. It is less well appreciated that imprinted gene domains also transcribe hundreds of microRNA and small nucleolar RNA genes and that these represent the densest clusters of small RNA genes in mammalian genomes. The evolutionary reasons for this remarkable enrichment of small regulatory RNAs at imprinted domains remain unclear. However, recent studies show that imprinted small RNAs modulate specific functions in development and metabolism and also are frequently perturbed in cancer. Here, we review our current understanding of imprinted small RNAs in the human genome and discuss how perturbation of their expression contributes to disease.     

Small regulatory RNAs controlled by genomic imprinting and their contribution to human disease

More than a hundred protein-coding genes are controlled by genomic imprinting in humans. These atypical genes are organized in chromosomal domains, each of which is controlled by a differentially methylated "imprinting control region" (ICR). How ICRs mediate the parental allele-specific expression of close-by genes is now becoming understood. At several imprinted domains, this epigenetic mechanism involves the action of long non-coding RNAs. It is less well appreciated that imprinted gene domains also transcribe hundreds of microRNA and small nucleolar RNA genes and that these represent the densest clusters of small RNA genes in mammalian genomes. The evolutionary reasons for this remarkable enrichment of small regulatory RNAs at imprinted domains remain unclear. However, recent studies show that imprinted small RNAs modulate specific functions in development and metabolism and also are frequently perturbed in cancer. Here, we review our current understanding of imprinted small RNAs in the human genome and discuss how perturbation of their expression contributes to disease.     

滇西北高山流石滩植物多样性

通过多次对滇西北高山流石滩野外实地考察、标本鉴定并查阅有关献,建立数据库统计得到流石滩种子植物共计29科、103属、519种。其中中国特有植物295种,占总数的56．8％,滇西北特有植物54种,占10．4％。有10种属的分布区类型(包括7个变型),北温带分布类型最多,占总属数的47．5％。在整个高山流石滩中,草本有455种,占总数的87．7％,其中多年生草本421种。流石滩植物中具有多种生态、生理适应方式,低矮平卧状植株、莲座状、垫状、极矮小草本、密集丛生是植物的重要适应方式。根茎及发达的肉质根或木质根是典型流石滩上的主要适应方式,分别占植物总数的19．7％,31．0％。果实中干果共计518种,其中蒴果298种。由于流石滩处于生态脆弱区,人为干扰易对生态系统造成危害。本对流石滩种子植物多样性组成分析,为合理保护和利用流石滩植物资源提供基础资料。     

陕西洋县药用植物群落土壤种子库特性研究

采用种子萌发法对洋县药用植物群落土壤种子库物种组成、单位面积种子密度、物种丰富度及与地上群落结构的关系进行了研究。结果显示,研究区内共有种子植物50种(包括药用植物21种),隶属于28科47属,其中草本植物45种、乔木5种;不同药用植物群落间土壤种子库种子密度差异显著,从大到小依次为:2年生凹叶厚朴(Magnolia officinalis Rehd.et Wils.subsp.biloba(Rehd.et Wils.)Law)4年生凹叶厚朴7年生凹叶厚朴11年生凹叶厚朴杜仲-凹叶厚朴(Eucommia ulmoides Oliver-Magnolia officinalis Rehd.et Wils.subsp.biloba(Rehd.et Wils.)Law)7年生厚朴(Magnolia officinalis Rehd.et Wils.)杜仲山茱萸(Cornus officinalis Sieb.et Zucc.)山茱萸-凹叶厚朴;土壤种子库具有表聚性,土层深度与种子数量成负相关;药用植物群落土壤种子库与地上群落结构相似性普遍较低。低林龄群落的土壤种子库密度大于高林龄群落,因此低林龄群落有利于天然更新,它们在植被恢复和生物多样性保护中的潜在价值更大。本研究结果可为洋县药用植物群落天然更新提供理论指导。