组蛋白去乙酰化抑制剂对拟南芥根尖干细胞微环境的影响

根系发育是植物生长的重要组成部分,该过程由多种信号转导途径共同调节。组蛋白乙酰化和去乙酰化的动态变化对基因表达具有关键的调控作用,而对其在根发育中功能的研究还不深入。本研究通过组蛋白去乙酰化酶抑制剂Trichostatin A（TSA）处理拟南芥,发现其主根生长受到抑制,分生区细胞数目变少。显微观察的结果表明TSA影响了根尖干细胞微环境。根尖微环境调控相关因子SCR和SHR的表达受TSA处理的影响并不明显,而PLT1/PLT2的表达受TSA强烈抑制。我们对生长素运输途径的分析发现在TSA处理条件下,PIN1表达只受轻微影响,而PIN2表达量明显下调。pDR5:GFP的结果表明TSA可能引起生长素在根尖的积累和分布变化。综上所述,TSA影响了拟南芥根尖干细胞微环境的维持,表明组蛋白的去乙酰化在根发育过程中发挥着重要作用。     

骨髓造血微环境与基质细胞的基因治疗

造血干细胞是所有免疫细胞和血细胞的来源，而造血微环境是造血干细胞增殖、发育和分化的场所，对造血干细胞发育为成熟血细胞起重要的调节作用。造血微环境（HematopoieticMicroenvironment，HME）的概念1970年首先由坦廷（Tentin）提出，当时认为它由骨髓中微血管系统、神经、网状细胞、细胞外基质及纤维组织等构成，对造血干细胞的分化成熟起调节作用。以后的研究证明，微环境中的基质细胞（StrormalCell，SC）及一些造血刺激因子是造血微环境的主要成份。1977年德克斯特（Dexter）建立了体外长期骨髓细胞培养系统地Long-TermBoneM…     

植物根尖分生组织干细胞调控模式

静止中心(QC)形成和干细胞区特化是植物根尖分生组织确立的标志。静止中心位于根尖分生组织中心,干细胞围绕在静止中心细胞周围。依赖于生长素的PLT途径和不依赖于生长素的SCR/SHR途径共同发挥维持静止中心细胞稳定的作用。静止中心和干细胞区的柱干细胞之间存在类似于WUS/CLV3的WOX5/ACR4/CLE40的反馈抑制调节途径,该调节途径维持着静止中心细胞和柱干细胞之间的平衡。静止中心和其他类型干细胞之间也可能存在类似的反馈抑制调节途径。生长素、细胞分裂素、赤霉素等植物激素信号在根干细胞功能发挥方面也起到重要作用,与各种基因一起组成根分生组织干细胞调控网络。     

细胞因子调控肌腱干细胞分化方向的研究进展

肌腱损伤是骨科常见疾病,随着老龄化社会程度的加重和体育运动的普及,其发病率不断增长,严重危害患者的生活质量.肌腱干细胞可向腱系分化,具有治疗肌腱损伤的良好前景,因此调控肌腱干细胞定向分化成为肌腱干细胞发挥临床疗效的关键环节.细胞因子对肌腱干细胞的分化方向具有重要的调节作用,目前研究发现包括转化生长因子-β(TGF-β)、骨形态发生蛋白(BMP)、成纤维细胞生长因子(bFGF)、白细胞介素(IL)、结缔组织生长因子(CTGF)、胰岛素样生长因子-1(IGF-1)、肝细胞生长因子(HGF)、早期生长反应因子(EGR-1)、前列腺素E2(PGE2)和P物质(SP)等细胞因子都具有调控其分化的作用,部分机制已被阐明,但由于影响因素十分复杂,尤其在体内常常是多种因子共同作用,因此还需进一步深入研究,为肌腱干细胞的临床应用寻求合适的方案.     

补髓生血颗粒剂对慢性再生障碍性贫血患者影响的实验研究

应用单标及双标免疫组织化学技术和酶联免疫法,对慢再生障碍性贫血患者骨髓CD34细胞、Fas 细胞、CD34 mP53表达细胞及血清细胞子IL-2、IL-3进行观察,结果表明,补髓生血颗剂能提高细胞、CD34mP53表达细胞百分率(P＜0.05),降低Fas 细胞分率(P＜0.05),降低IL-2水平(P＜0.05).提示:1)补髓生血颗粒剂可能能通过提高抑制凋亡因mP53表达,降低促进凋亡Fas抗原表达抑制血干细胞的过度凋亡.2)补髓生血颗粒剂能够降低造血负调控因子水平,同时提高造血正调控因子水平,并可能通过造血因子调控凋亡相关基因的表达,从而抑制造血干细胞的过度凋亡.     

拟南芥茎尖干细胞调控机制的研究进展

植物茎尖干细胞是位于植物顶端一团具有无限增殖能力的细胞,它是植物整个地上部分发育的源泉.干细胞分裂产生的子细胞一部分用来保持自我更替,另一部分形成器官原基,进而使其处于一种动态平衡状态,来维持植物甚至可长达千年的生长周期.现代分子生物学与遗传学表明这种动态平衡的维持受到来自干细胞微环境的各种因素的精确调控.其中起核心作用的是由WUSCHEL(WUS)基因与CLAVATA(CLV)基因之间形成的负反馈调节环,而其他生物学因素如细胞分裂素、可以移动的小RNAs和表观遗传作用等最终都作用于这一负反馈调节环,另外与WUS-CLV信号通路相平行的SHOOTMERISTEMLESS(STM)信号通路在干细胞维持中也发挥着积极的作用.在此主要综述了模式植物拟南芥(Arabidopsis thaliana)茎尖干细胞维持分子机制的最新研究进展.     

新疆生地所处理油田作业污水研究取得重要进展

[遗传与发育生物学研究所]近年来，诱导多功能干细胞（iPS）引发了生命科学与医学界干细胞研究的热潮。于细胞广泛应用的前提是明确其自我更新和定向分化的调控机制。OCT4是参与调控胚胎干细胞自我更新和维持其全能性的最为重要的转录因子之一，同时也是体外建立诱导多功能干细胞（iPS）的关键基因。     

国外科技期刊亮点

Nanog蛋白的干细胞调控因子作用重新估定来自英国爱丁堡大学生命科学学院的Ian Chambers博士和其他研究人员共     

国外科技期刊亮点

脂肪细胞与造血研究最新进展造血干细胞微环境中包含大量成骨细胞、内皮细胞及少量脂肪细胞。通常脂肪细胞在骨髓造血干细胞微环境中的含量是很低的,临床上如果检测发现骨髓中含有大量脂肪细胞,就表明骨髓发育不良,不利于生成造血细胞。比如恶性贫血     

利用内源性干细胞原位再生晶状体治疗婴幼儿白内障

 利用内源性干细胞进行组织器官的修复和再生是再生医学研究的最终目标。婴幼儿白内障是幼儿致盲性眼病的首要病因,目前尚无有效治疗手段。本研究组从哺乳动物内成功分离并获得了晶状体上皮干细胞,证明Pax6和Bmi1是维持其分化和自我更新的关键因子,并以保留内源性干细胞为目标,设计了全新的白内障术式。相较于传统术式,新术式最大程度地保留了内源性干细胞、基底膜和微环境,在新西兰兔、食蟹猴和先天性白内障患儿内实现了功能性晶状体的再生。研究结果为白内障提供了全新的治疗策略并为组织再生及内源性干细胞的应用提供了全新的范例。     

束花石斛和黄花石斛的光合特性研究

研究了大花组的束花石斛和黄花石斛的光合生理,结果表明,2种石斛叶片的解剖结构为异面叶,气孔仅分布在下表面,具气孔盖,叶脉维管束鞘不含叶绿体,无花环型结构,具C3植物特征.2种石斛的光补偿点(LCP)和光饱和点(LSP)分别为5～10μmol/(m2.s)和850～900μmol/(m2.s),最大光合速率(Pn)约为6μmol/(m2.s);CO2补偿点和饱和点分别为80～90μmol/mol和800μmol/mol;光合作用的最适温度在26～30℃.Pn日变化为双峰型曲线,首峰出现在11:00左右,最大光合速率在5～6μmol/(m2.s),次峰出现在15:00左右,夜间不吸收CO2.PEPCase活性低,RuBPCase和GO酶活性较高.以上结果表明,束花石斛和黄花石斛光合作用碳同化途径属C3植物类型,具有半阴生植物的特点.     

Conserved factors regulate signalling in Arabidopsis thaliana shoot and root stem cell organizers

Throughout the lifespan of a plant, which in some cases can last more than one thousand years, the stem cell niches in the root and shoot apical meristems provide cells for the formation of complete root and shoot systems, respectively. Both niches are superficially different and it has remained unclear whether common regulatory mechanisms exist. Here we address whether root and shoot meristems use related factors for stem cell maintenance. In the root niche the quiescent centre cells, surrounded by the stem cells, express the homeobox gene WOX5 (WUSCHEL-RELATED HOMEOBOX 5), a homologue of the WUSCHEL (WUS) gene that non-cell-autonomously maintains stem cells in the shoot meristem. Loss of WOX5 function in the root meristem stem cell niche causes terminal differentiation in distal stem cells and, redundantly with other regulators, also provokes differentiation of the proximal meristem. Conversely, gain of WOX5 function blocks differentiation of distal stem cell descendents that normally differentiate. Importantly, both WOX5 and WUS maintain stem cells in either a root or shoot context. Together, our data indicate that stem cell maintenance signalling in both meristems employs related regulators.     

Endothelial and perivascular cells maintain haematopoietic stem cells

Several cell types have been proposed to create niches for haematopoietic stem cells (HSCs). However, the expression patterns of HSC maintenance factors have not been systematically studied and no such factor has been conditionally deleted from any candidate niche cell. Thus, the cellular sources of these factors are undetermined. Stem cell factor (SCF; also known as KITL) is a key niche component that maintains HSCs. Here, using Scf(gfp) knock-in mice, we found that Scf was primarily expressed by perivascular cells throughout the bone marrow. HSC frequency and function were not affected when Scf was conditionally deleted from haematopoietic cells, osteoblasts, nestin-cre- or nestin-creER-expressing cells. However, HSCs were depleted from bone marrow when Scf was deleted from endothelial cells or leptin receptor (Lepr)-expressing perivascular stromal cells. Most HSCs were lost when Scf was deleted from both endothelial and Lepr-expressing perivascular cells. Thus, HSCs reside in a perivascular niche in which multiple cell types express factors that promote HSC maintenance.     

Somatic control over the germline stem cell lineage during Drosophila spermatogenesis

Stem cells divide both to produce new stem cells and to generate daughter cells that can differentiate. The underlying mechanisms are not well understood, but conceptually are of two kinds. Intrinsic mechanisms may control the unequal partitioning of determinants leading to asymmetric cell divisions that yield one stem cell and one differentiated daughter cell. Alternatively, extrinsic mechanisms, involving stromal cell signals, could cause daughter cells that remain in their proper niche to stay stem cells, whereas daughter cells that leave this niche differentiate. Here we use Drosophila spermatogenesis as a model stem cell system to show that there are excess stem cells and gonialblasts in testes that are deficient for Raf activity. In addition, the germline stem cell population remains active for a longer fraction of lifespan than in wild type. Finally, raf is required in somatic cells that surround germ cells. We conclude that a cell-extrinsic mechanism regulates germline stem cell behaviour.     

Centrosome misorientation reduces stem cell division during ageing

Asymmetric division of adult stem cells generates one self-renewing stem cell and one differentiating cell, thereby maintaining tissue homeostasis. A decline in stem cell function has been proposed to contribute to tissue ageing, although the underlying mechanism is poorly understood. Here we show that changes in the stem cell orientation with respect to the niche during ageing contribute to the decline in spermatogenesis in the male germ line of Drosophila. Throughout the cell cycle, centrosomes in germline stem cells (GSCs) are oriented within their niche and this ensures asymmetric division. We found that GSCs containing misoriented centrosomes accumulate with age and that these GSCs are arrested or delayed in the cell cycle. The cell cycle arrest is transient, and GSCs appear to re-enter the cell cycle on correction of centrosome orientation. On the basis of these findings, we propose that cell cycle arrest associated with centrosome misorientation functions as a mechanism to ensure asymmetric stem cell division, and that the inability of stem cells to maintain correct orientation during ageing contributes to the decline in spermatogenesis. We also show that some of the misoriented GSCs probably originate from dedifferentiation of spermatogonia.