精原干细胞研究进展

精原干细胞（spermatogonial stem cells,SSCs）是各种雄性动物生殖细胞的母细胞,是一群具有自我更新和分化潜能的细胞,并且在雄性个体中精原干细胞与下一代的遗传背景密切相关。因此,精原干细胞在细胞生物学、医学、转基因等领域的研究有着广阔的应用前景。文章根据国内外相关研究进展,对精原干细胞的生物学特性、分离纯化与培养、移植等作一概述。     

Changes in the composition of the extracellular matrix accumulated by mesenchymal stem cells during in vitro expansion

One of the approaches to preserve the properties of mesenchymal stem cells (MSCs) during in vitro expansion is to use cell culture substrates. MSCs are known to generate the extracellular matrix (ECM) proper to preserve their proliferative capacity in vitro, but extensive expansion is considered to deprive MSCs of the capacity to prepare such ECM. In order to examine the features of ECM proper that is required to preserve the proliferative capacity of MSCs, we analyzed the changes in the composition of ECM accumulated by MSCs during in vitro expansion. Biochemical and immunological analysis showed that collagen and laminin content decreased during expansion. Immunofluorescence and ultrastructural analyses showed that the ECM structure changed from a dynamic fibrous, porous and steric structure to a static, crammed, and planar one. The results of Western blotting analysis suggested loose intermolecular association in ECM molecules accumulated by extensively proliferated MSCs. The ECM prepared by extensively proliferated MSCs was less effective to recover their proliferative capacity than that prepared by less proliferated cells. Our results suggest that a cell culture substrate to expand MSCs requires abundance in collagen and basement membrane components, and steric, porous and fibrous structure in which ECM molecules are tightly associated.     

Perspectives of germ cell development in vitro in mammals

Pluripotent stem cells, such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) are able to differentiate into all cell lineages of the embryo proper, including germ cells. This pluripotent property has a huge impact on the fields of regenerative medicine, developmental biology and reproductive engineering. Establishing the germ cell lineage from ESCs/iPSCs is the key biological subject, since it would contribute not only to dissection of the biological processes of germ cell development but also to production of unlimited numbers of functional gametes in vitro. Toward this goal, we recently established a culture system that induces functional mouse primordial germ cells (PGCs), precursors of all germ cells, from mouse ESCs/iPSCs. The successful in vitro production of PGCs arose from the study of pluripotent cell state, the signals inducing PGCs and the technology of transplantation. However, there are many obstacles to be overcome for the robust generation of mature gametes or for application of the culture system to other species, including humans and livestock. In this review, we discuss the requirements for a culture system to generate the germ cell lineage from ESCs/iPSCs.     

绿汁发酵液和纤维素酶对香蕉茎玉米面粉混合青贮品质的影响

旨在研究绿汁发酵液和纤维素酶对香蕉茎与玉米面粉混合青贮发酵品质的影响。调制香蕉茎单贮(BSS)和香蕉茎玉米面粉混合青贮,在香蕉茎玉米面粉混合青贮中,设对照组(CON),添加2mL/kg绿汁发酵液(FGJ)组,添加0.05g/kg、0.15g/kg和0.25g/kg纤维素酶(CEL1、CEL2和CEL3)的3个水平组,添加FGJ+CEL1(MIX1)、FGJ+CEL2(MIX2)和FGJ+CEL3(MIX3)的3个混合组。每个处理重复3次。常温下贮存60d开封,测定青贮的发酵品质和化学成分。香蕉茎青贮混合玉米面粉后,pH和氨态氮/总氮(AN/TN)极显著降低。各添加剂在改善青贮的干物质方面均有不同的影响。在3个CEL组和3个MIX组中,丁酸(BA)含量有随着CEL水平的增加而减少的趋势。3个MIX组的酸性洗涤纤维显著或极显著低于FGJ组(P0.05,P0.01);3个MIX组分别在干物质回收率(DMR)和pH上优于CEL组。结果表明:香蕉茎玉米面粉混合青贮的效果优于香蕉茎单独青贮。各添加剂均能改善青贮品质,且混合添加绿汁发酵液和纤维素酶的青贮效果优于单独添加。     

人胎儿肺间质干细胞染色体制备方法研究

研究了人胎儿肺间质干细胞染色体的制备方法,并对其染色体进行分析。结果表明,第5代细胞培养44 h,第15代细胞培养42 h,经终浓度0．025μg/mL秋水仙素作用2 h,0．075 mol/L KCl低渗25 min,正常核型比率最高,分别达到85．1%(171/201)和80．0％(172／215)。     

元宝枫树干液流的时空变异性研究

该研究应用热扩散式边材茎流计,对北京植物园绿地中元宝枫树干液流的时空变异特征进行了观测.研究结果显示:树干液流的日变化和季节差异与太阳辐射日变化和季节差异具有较好的一致性,夏季太阳升起比春秋早,落日比春秋晚,相应地树干液流启动夏季比春秋季早,进入低谷比春秋季晚;元宝枫为春季耗水性树种,树干平均液流速率春季0·00188cm/s、夏季0·00112cm/s、秋季0·00086cm/s;元宝枫树干液流存在明显的方位差异,同一样木,液流最大方位的流速可达平均值的122·1%,最小为平均值的86·3%,在同一株样木上,液流的方位差异较为稳定,不同样木液流最大和最小的方位不同,树干液流的方位差异与冠幅大小无关;在垂直高度上,春夏两季上部液流的波动节律明显早于下部和中部,液流速率上部最大,中部次之,下部最小.     

紫花苜蓿喷施微肥效果初报

对紫花苜蓿进行微肥喷施试验,结果显示:喷施微肥能显著提高其草产量,其M2C2处理草产量增幅最大,达到38.22%;并能促进其干鲜比的增加,其M2C1处理干鲜比最大;且对其叶茎比也有显著影响,其M1C1处理叶茎比最大,而M2C2处理叶茎比最小。     

烤烟上部叶带茎烘烤研究

研究烤烟上部烟叶一次性不带茎烘烤和带茎烘烤过程中水分代谢情况、内在化学品质、外观质量、经济效应以及DNA、RNA中的放射性强度,并对两种烘烤方法进行对比,发现带茎烘烤时烟茎中的水分能进入烟叶中参与代谢,但根据同位素示踪法对DNA、RNA中放射性的测定发现不论是带茎烘烤还是一次性不带茎烘烤各时期茎秆或叶柄的水分参与了叶片中核酸代谢,但都不强,对烘烤后的烟叶内在化学品质和外观质量进行分析发现带茎烘烤的烟叶品质相对较一次性不带茎烘烤好.     

大鼠骨髓间充质干细胞的分离与培养

为了确定大鼠骨髓间充质干细胞(Mesenchymal stem cells,MSCs)体外分离和培养的方法,建立了稳定的MSCs体外培养扩增体系,通过密度梯度离心和贴壁筛选法分离培养大鼠MSCs,观察了细胞的形态,研究了其增殖及生长特征,并应用流式细胞术测定了细胞周期及CD29,CD44,CD45和HLA-DR的表达。结果表明,在体外培养条件下大鼠MSCs贴壁生长,为成纤维细胞样;CD45和HLA-DR的表达呈阴性,CD29和CD44的表达呈阳性;细胞周期的G0/G1期约占95%,具有原始细胞的特征。说明建立的体外培养扩增体系可获得形态单一、生长稳定、增殖性较强、较均一的大鼠MSCs。     

扦插密度与氮、钾肥用量对浙薯13产量及经济效益的影响

选择扦插密度、尿素用量和硫酸钾用量为试验因子,采用二次饱和D-最优设计布置田间参数试验。建立了浙薯13产量和净产值回归方程,优化并提出了供试农艺因子组合方案:扦插密度3 300-3 600株/667m2;追肥尿素用量20-24 kg/667m2,基肥硫酸钾用量20-25 kg/667m2。