Teratocarcinomas and mammalian embryogenesis

In the last decade there has emerged an appreciation of the remarkable similarity between the cells that give rise to teratocarcinomas in mice and the cells that give rise to the developing mouse embryo. The resemblance is so close that in certain instances the tumor stem cells can join with their embryonic counterparts and develop into a completely normal mouse. The availability of stem cell lines isolated from mouse teratocarcinomas has made possible a number of new biochemical, immunological, and genetic approahes to the study of early mammalian development.     

Introduction of a normal human chromosome 11 into a Wilms' tumor cell line controls its tumorigenic expression

The development of Wilms' tumor, a pediatric nephroblastoma, has been associated with a deletion in the p13 region of chromosome 11. The structure and function or functions of this deleted genetic material are unknown. The role of this deletion in the process of malignant transformation was investigated by introducing a normal human chromosome 11 into a Wilms' tumor cell line by means of the microcell transfer technique. These variant cells, derived by microcell hybridization, expressed similar transformed traits in culture as the parental cell line. Furthermore, expression of several proto-oncogenes by the parental cells was unaffected by the introduction of this chromosome. However, the ability of these cells to form tumors in nude mice was completely suppressed. Transfer of other chromosomes, namely X and 13, had no effect on the tumorigenicity of the Wilms' tumor cells. These studies provide support for the existence of genetic information on chromosome 11 which can control the malignant expression of Wilms' tumor cells.     

An in vivo model of somatic cell gene therapy for human severe combined immunodeficiency.

Deficiency of adenosine deaminase (ADA) results in severe combined immunodeficiency (SCID), a candidate genetic disorder for somatic cell gene therapy. Peripheral blood lymphocytes from patients affected by ADA- SCID were transduced with a retroviral vector for human ADA and injected into immunodeficient mice. Long-term survival of vector-transduced human cells was demonstrated in recipient animals. Expression of vector-derived ADA restored immune functions, as indicated by the presence in reconstituted animals of human immunoglobulin and antigen-specific T cells. Retroviral vector gene transfer, therefore, is necessary and sufficient for development of specific immune functions in vivo and has therapeutic potential to correct this lethal immunodeficiency.     

植物体细胞胚胎发生及其分子调控机制研究进展

植物的每个细胞都包含着该物种的全部遗传信息,具备发育成完整植株的遗传能力,这被称为植物细胞的全能性。体细胞胚胎(体胚)发生是指在没有受精的情况下,由体细胞或营养细胞发育成胚胎,是诱导植物细胞全能性的一种形式。体胚发生在种质资源保存、种苗生产、分子育种和植物基础研究等方面都有着广泛的应用,已成为重要的植物生物技术工具和研究平台。多年来的分子遗传学研究表明:体胚发生受到由众多转录因子、激素信号途径及表观遗传修饰等构成的复杂网络的调控。本研究概述了植物体胚发生的途径,并重点综述了体胚发生关键基因的功能与调控机制、体胚发生的表观遗传修饰以及体胚发生关键基因在基因工程中的应用。随着研究的深入和新技术的出现,体胚发生过程中涉及的代谢组分动态变化、转录调控、激素信号转导与表观遗传调控等复杂生物学过程有望得到更深入地阐释,将更进一步地解析植物体胚发生的分子调控机制。此外,利用体胚发生关键基因的功能与调控机制,开发更高效的体胚诱导和遗传转化方法,有望为更多植物的基因功能研究和遗传改良提供新的思路和技术。参81     

分子标记技术新进展——以几种新型标记为例

DNA分子标记是基于DNA序列变异的遗传标记,自诞生至今已开发出几十种分子标记,各有优缺点,尽管容量差异显著,但都具有一个共同点,即必须使用分子杂交、聚合酶链式反应、电泳等检测手段,要么效率低,要么成本高。海量平行测序技术已广泛应用于基因组测序,同时也在逐步影响高通量、低成本新型分子标记的开发和应用。简要介绍了几种新型分子标记及其在遗传学研究上的应用。     

化学趋化因子与家畜疾病

在人类和小鼠，已经发现并确定了50余种化学趋化因子和20余种化学趋化因子受体，而在兽医领域中，已经发现并确定的化学趋化因子及其受体数量较少。化学趋化因子及其受体不仅在机体T、B淋巴细胞发育、成熟、归巢以及免疫反应中起着重要作用，还在炎症反应中与炎症细胞浸润到组织损伤部位过程中起着关键性的作用。化学趋化因子及其受体还与许多家畜疾病的发生、发展密切相关。作者还介绍了动物病毒模仿编码的化学趋化因子或化学趋化因子结合蛋白及可能的生物学功能并讨论了化学趋化因子及其受体研究在兽医领域的发展前景。     

大豆分子育种研究新进展

分子育种是当今世界大豆产业发展的主要推动力,已成为国际大豆种业竞争的核心技术。介绍了2012-2013年间国内外大豆分子育种研究的新进展：以高通量测序为基础的功能基因组学研究更深入、更广泛;克隆并验证了与开花、产量、结瘤和抗逆性等重要性状相关的基因;发掘出一批新的分子标记或QTL,强化了传统分子标记与新技术、新方法的有机结合;在遗传转化体系优化方面取得了一些新进展,并在大豆中对一些目标基因进行了功能鉴定;一批具有抗虫、耐除草剂等单一及复合性状的转基因大豆新品种获得多国安全认证,允许进口食用、饲用或商业化种植,并对今后一段时间内大豆分子育种领域的发展趋势进行了展望。     

Synthetic biology: integrated gene circuits

A major goal of synthetic biology is to develop a deeper understanding of biological design principles from the bottom up, by building circuits and studying their behavior in cells. Investigators initially sought to design circuits "from scratch" that functioned as independently as possible from the underlying cellular system. More recently, researchers have begun to develop a new generation of synthetic circuits that integrate more closely with endogenous cellular processes. These approaches are providing fundamental insights into the regulatory architecture, dynamics, and evolution of genetic circuits and enabling new levels of control across diverse biological systems.     

不同环境下油菜籽饼粕甘氨酸含量的发育遗传机理研究

采用条件和非条件遗传分析方法,利用两年的试验数据,分析了油菜籽胚(子叶)、细胞质和母体植株等不同遗传体系的遗传主效应及环境互作效应对油菜籽饼粕甘氨酸含量的影响。结果显示,不同发育时期的甘氨酸含量的表现受不同遗传体系的遗传主效应和环境互作效应的控制,以环境互作效应为主。在不同遗传体系的基因效应中,除花后36 d的胚效应较大外,各发育时期以母体效应为主导,母体显性主效应和加性互作效应起主要作用。条件遗传分析表明,控制甘氨酸含量表现的数量基因在中期和前期表达最为活跃;中期的净遗传效应最大,大量的微效多基因被激活表达。油菜籽饼粕甘氨酸含量的狭义遗传率较高,多数发育时期是以母体和细胞质两部分的遗传率为主。在低世代时,根据母体植株油菜籽甘氨酸含量的总体表现进行选择,可望取得较好的效果。     

Rabies viruses increase in virulence when propagated in neuroblastoma cell culture

Several strains of attenuated rabies virus lacking the capacity to kill adult mice acquired a high lethal potential for mice after one to five serial passages in murine or human neuroblastoma cells. The virulence acquired after passage in neuroblastoma cells is a stable genetic trait retained during subsequent passage of viruses in nonneuroblastoma cell systems.     

Generation of CRISPR/Cas9-mediated lactoferrin-targeted mice by pronuclear injection of plasmid pX330

Lactoferrin is a member of the transferrin family of multifunctional iron binding glycoproteins. While numerous physiological functions have been described for lactoferrin, the mechanisms underlying these functions are not clear. To further study the functions and mechanisms of lactoferrin, we modified the lactoferrin promoter of mice using the CRISPR/Cas9 system to reduce or eliminate lactoferrin expression. Seven mice with lactoferrin promoter mutations were obtained with an efficiency of 24% (7/29) by injecting the plasmid pX330, expressing a small guide RNA and human codon-optimized SpCas9, into fertilized eggs of mice. Plasmid integration and off-targeting of pX330 were not detected. These results confirmed that pronuclear injection of a circular plasmid is a feasible and efficient method for targeted mutagenesis in mice.     

Making sense of eukaryotic DNA replication origins

DNA replication is the process by which cells make one complete copy of their genetic information before cell division. In bacteria, readily identifiable DNA sequences constitute the start sites or origins of DNA replication. In eukaryotes, replication origins have been difficult to identify. In some systems, any DNA sequence can promote replication, but other systems require specific DNA sequences. Despite these disparities, the proteins that regulate replication are highly conserved from yeast to humans. The resolution may lie in a current model for once-per-cell-cycle regulation of eukaryotic replication that does not require defined origin sequences. This model implies that the specification of precise origins is a response to selective pressures that transcend those of once-per-cell-cycle replication, such as the coordination of replication with other chromosomal functions. Viewed in this context, the locations of origins may be an integral part of the functional organization of eukaryotic chromosomes.     

RNA干扰机制及其主要蛋白因子研究进展

RNA干扰(RNA interference, RNAi)是由双链RNA(double stranded RNA, dsRNA)分子介导的、在mRNA水平上关闭相应序列基因表达、使其沉默的过程。RNAi作为一种古老而保守的基因沉默机制,广泛存在于真核生物体内,在细胞的发育调控、抗病毒防御、修复遗传损伤、调节正常的基因等生命过程中起着重要的作用。RNAi机制可以分为3个阶段：启动阶段、效应阶段及扩增阶段。RNAi干扰相关的主要蛋白因子有Dicer酶、Argonaute(AGO) 蛋白家族和RNA依赖的RNA聚合酶(RNA\|dependent RNA polymerase, RdRP)。文章对RNAi机制及其相关主要蛋白因子进行简要综述。     

历史和现实双重视角下中国基层图书馆属性和功能定位

[目的/意义]基层图书馆从无到有,发展至成为新时代基层文化阵地,其属性和功能定位随着时代发展较历史上更为丰富,准确定位新时代基层图书馆属性和功能,有利于有效发挥基层图书馆的各项文化功能,关系到乡村振兴战略和坚定文化自信的顺利推进。[方法/过程]文章回顾了基层图书馆的发展历史,从历史视角总结分析基层图书馆属性和功能随时代发展变化的特点,结合目前基层图书馆的现实定位,观察和分析中国基层图书馆的属性及其功能定位。[结果/结论]随着时代需求的变化,新时代基层图书馆的属性从动能、使命、思维3个维度进行了拓展,其功能也因融入了文旅融合、文化兴农、新型农民培育、乡村振兴、文化自信等方面的需求而变得更为丰富。     

童乐冲剂药效学试验

童乐冲剂是用于防治儿童厌食、增进食欲、促进生长发育、增强免疫的一种新型儿童保健药．本文报道了该药对小鼠进食量和体重、对环磷酰胺受损小鼠免疫器官和免疫功能以及促进小鼠学习记忆作用的影响．结果表明，该药对动物上述指标均有增进作用．     

Mutants of pertussis toxin suitable for vaccine development

Immunization with chemically detoxified pertussis toxin can prevent severe whooping cough with an efficacy similar to that of the cellular pertussis vaccine, which normally gives unwanted side effects. To avoid the reversion to toxicity and the loss of immunogenicity that may follow chemical treatment of pertussis toxin, inactive toxins were constructed by genetic manipulation. A number of genetically engineered alleles of the pertussis toxin genes, constructed by replacing either one or two key amino acids within the enzymatically active S1 subunit, were introduced into the chromosome of strains of Bordetella pertussis, B. parapertussis, and B. bronchiseptica. These strains produce mutant pertussis toxin molecules that are nontoxic and immunogenic and that protect mice from the intracerebral challenge with virulent Bordetella pertussis. Such molecules are ideal for the development of new and safer vaccines against whooping cough.     

茄科作物绿原酸的生物合成及调控机制研究进展

绿原酸是植物体内重要的多酚类化合物,在植物生长发育、抗病虫害、抗寒及其他逆境等方面发挥重要作用,同时具有多种药理功能,包括抗炎、抗菌、抗病毒、抗癌、抗紫外光与辐射、免疫调节、降血脂、降血糖等,在功能性食品、营养补充剂、食品原料、化工和新药开发等方面的应用潜力巨大。番茄、茄子、辣椒、马铃薯和烟草都是世界上重要的经济作物,它们均是茄科植物的重要种类,也是绿原酸的重要来源,其果实或营养器官中的绿原酸含量具有较大差异,且绿原酸合成代谢是遗传和环境等因素共同决定的复杂生物学过程。因此,茄科作物绿原酸的生物合成及其调控的分子机制研究对作物遗传改良具有重要的理论意义与应用价值。本文概述了绿原酸在以上 5 种茄科作物中的含量情况、绿原酸的生物合成途径及其转录调控分子机制,以及基因型差异、环境因素、栽培措施等因素对茄科作物绿原酸含量影响等方面的研究进展,旨在为茄科作物绿原酸开发利用、高绿原酸茄科作物种质资源创制以及新品种培育等提供理论依据。     

Hyperprolinemia and prolinuria in a new inbred strain of mice, PRO-Re

A hyperprolinemia was discovered, in a new inbred strain of mice, which was equivalent to about a sevenfold elevation above the concentration of proline in the blood of either of the original parental lines, or of 12 other inbred strains with diverse genetic constitution. In addition, mice of this PRO/Re strain exhibited a marked prolinuria, whereas the other 14 inbred strains had no proline detectable in their urine.     

CRISPR/Cas9基因组定向编辑技术的发展与在作物遗传育种中的应用

CRISPR/Cas9系统是近年发展起来的、由导向RNA介导的基因组定向编辑技术。总结了CRISPR/ Cas9基因组定向编辑技术的发展历程,并综述了其在作物遗传育种研究中的多方面应用。CRISPR/Cas系统是存在于大多数细菌与所有古生菌中的一种后天免疫系统,以消灭外来质体或者噬菌体。 根据Cas蛋白组分及氨基酸序列不同,已发现的CRISPR/Cas系统可以分为3种不同类型,Ⅰ型、Ⅱ型和Ⅲ型。其中,Ⅱ型是以Cas9蛋白及导向RNA为核心组份,组成较为简单,是目前经过改造用于开发基因组定向编辑技术的主要类型。自CRISPR/Cas9技术体系首先在人类与动物细胞系中建立后,经过改造的CRISPR/Cas9系统被迅速地应用于拟南芥、烟草、高粱、水稻、小麦、玉米等不同植物基因组的定向编辑研究中。CRISPR/Cas9与ZFNs或TALENs一样都是通过自身的核酸内切酶活性引起靶位点DNA序列双链断裂,然后通过非同源末端连接或同源重组介导的修复2种方式引入突变。至今,在多种作物中已实现诱导产生多种定点突变（包括插入、缺失或修饰等）,并可获得较高的突变诱导率和可稳定遗传的基因组编辑后代植株。与ZFNs或TALENs技术相比,CRISPR/Cas9技术可以实现对基因组中多个靶基因同时进行编辑,从而可以用来修饰同一基因家族中的不同成员或同一代谢途径中的不同调控基因,为其一大优势。由于CRISPR/Cas9技术具有突变诱导率高、成本低、易于操作及可以多重基因编辑等特点,已成为具有广阔应用前景的作物遗传改良与育种研究的分子操作系统。CRISPR技术除了可以对基因组中不同靶基因进行定向编辑以外,还可以广泛地应用于基因表达调控研究、细胞定位运输系统研究及新型RNA沉默系统构建等方面。基因组编辑技术是继转基因技术之后人类对生物进行遗传操作的又一个革命性技术。但是,与转基因技术相比,CRISPR/Cas9基因组编辑技术操作更加简单、快捷。应用CRISPR/Cas9基因组编辑技术进行育种可以不引入外源基因,在进行基因组编辑之后可以不留下转基因的痕迹,从而导致定义转基因生物的不明确性,因此,政府监管部门是否应该按照转基因的管理办法来监管CRISPR/Cas9技术的应用尚有待决定。