DNA甲基化--浅谈发育生物学中的几个问题

甲基化和非甲基化是一种碱基修饰 ,现已表明DNA甲基化程度与基因表达的调控有关。在哺乳动物的 DNA中常常有 2 %～ 7%的胞嘧啶被酶所修饰 ,形成5 -甲基胞嘧啶。这种现象在卫星 DNA中很明显 (赵寿元等 ,1996 )。动物染色质中平均有 70 %的 CCGG甲基化(童克中 ,1996 )。甲基化现象发生在 5′- CG- 3′二核苷酸上。那么甲基化在基因的表达和调控中有着什么作用 ,又是如何得到这样的结论呢 ?人们假设了这样一种情况 :基因无论在激活状态或是在钝化状态都包含相同的核苷酸。由此 ,可以说在红血细胞前体中的 β珠蛋白基因与同一个动物的成纤…     

植物木质部发育生物学研究

本文主要介绍植物木质部发生和发育的研究历史及其进展情况,涉及的学科有生理学、系统发育学、遗传学和结构植物学等。评述了从整体、器官、组织细胞直至分子水平的研究方法、研究思路及机理分析的各种结果和假说。企望对植物木质部发育生物学的研究概况有一个比较全面的认识。     

植物木质部发育生物学研究

本文主要介绍植物木质部发生和发育的研究历史及其进展情况，涉及的学科有生理学、系统发育学、遗传学和结构植物学等。评述了从整体、器官、组织细胞直至分子水平的研究方法、研究思路及机理分析的各种结果和假说。企望对植物木质部发育生物学的研究概况有一个比较全面的认识     

畸胎瘤--浅谈发育生物学中的一些问题

在哺乳动物生殖细胞以及早期的卵裂球中包含了其继续不断发育的全部遗传信息。如果这样的细胞变成恶性的话 ,其结果就会导致畸胎瘤的发生。这种类型的肿瘤在睾丸和卵巢中也会自然发生。实验证实仅仅通过把哺乳动物的胚泡移植在不是子宫内的其他的位置上就可以诱发畸胎瘤的发生。无论是自然发生还是通过试验诱导产生 ,结果显示畸胎瘤中总包含一些未分化干细胞 ,其生物化学和发育的特点与内细胞团的细胞极为近似。这些干细胞 (常被称为胚性癌细胞 )不仅能够分裂而且还可以分化成许多组织 ,其中包括肠和呼吸道上皮 ,肌肉 ,神经 ,软骨和骨骼。这…     

进化发育生物学--发育、进化和遗传的再联合

发育生物学和进化生物学,以及遗传学历史上曾一度是彼此不分的统一体,后来由于各自研究重点的不同和相应研究手段的独立发展彼此分道扬镳了。如今,由于分子遗传学研究手段的革新使得基因序列测定成为分析发育机理、区分物种和评估种间亲缘关系的常规手段,三者又在基因水平上再度统一起来了,并形成一门被称为进化发育生物学（ｅｖｏｌｕｔｉｏｎａｒｙ ｄｅｖｅｌｏｐｍｅｎｔａｌ ｂｉｏｌｏｇｙ）的新学科。     

畸胎学--浅谈发育生物学中的一些问题

在发育生物学的研究中 ,畸胎学也是其中的一个组成部分。一个有机体胚胎的发育怎么就会形成一个畸形呢 ?引起畸形出现的原因是怎样的 ?一个有机体的发育是细胞分裂、细胞迁移、细胞的相互作用、基因调节、以及分化方面的相互作用、相互影响、相互协调、相互制约的复杂的发育过程。如果对于这一过程稍稍有一些外来因素的干扰 ,那么就会造成胚胎的畸形。据估计 ,事实上大约有一半胚胎不能正常分娩而死亡 ,只是这其中的绝大多数在受精活动的早期就表现出不正常而根本就没有可能植入到子宫中。其他的一些虽然只是在子宫着床 ,但无法正常怀孕。实…     

2n/4n嵌合体胚胎的发育特点及其应用

2n/4n嵌合体是指用二倍体的胚胎细胞和四倍体的胚胎细胞聚合所形成的嵌合体。这种嵌合体在胚胎的发育过程中。四倍体来源的细胞在分布上具有一定的倾向性,即倾向于分布在胚外组织,如胎盘;而在胎儿本身的组织中,很少能找到四倍体细胞的存在,就2n/4n嵌合体胚胎的制作、嵌合体胚胎的发育特点及该技术的可能应用进行了综述。     

高中生物学教科书中有关“胚胎工程”的问题解析

对5个版本高中生物学教科书中“胚胎工程”的内容进行比较,列举6个教师常见的疑惑问题,查阅文献逐一探析问题,解答疑惑。     

发育生物学探究式教学探讨

发育生物学是目前生物科学中发展较迅速、应用前景较广阔的学科之一。目前作为本科生的重要专业选修课程, 其授课内容的前沿化对传统的教学模式提出了挑战。文章主要讨论了发育生物学的教学现状, 详细阐述了首都师范大学引用英文原文文献特别是诺贝尔奖获奖者经典文献进行教学的情况, 总结了学生在课堂上做报告以及课下参与网络讨论的模式相结合的优势, 并就如何进一步有效地提高教学质量提出了一些建议。     

Chimeric contribution of human extended pluripotent stem cells to monkey embryos ex vivo

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Generation of Functional Organs Using a Cell-Competitive Niche in Intra- and Inter-species Rodent Chimeras

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Chimeric mice reveal clonal development of pancreatic acini, but not islets

Intestinal crypt stem cells establish clonal descendants. To determine whether the pancreas is patterned by a similar process, we used embryonic stem (ES) cell chimeric mice, in which male ES cells were injected into female blastocysts. Fluorescence in situ hybridization for the Y chromosome (Y-FISH) revealed clonal patterning of ES-derived cells in the adult mouse small intestine and pancreas. Intestinal crypts were entirely male or entirely female. Villi contained columns of male or female epithelial cells, consistent with upward migration of cells from the crypts which surround them. Within the exocrine pancreas, acini were entirely male or entirely female, consistent with patterning from a single stem/progenitor cell. Pancreatic islets contained a mixture of male and female cells, consistent with patterning from multiple progenitors. Male-female chimeric mice demonstrate that the adult mouse exocrine pancreatic acinus is patterned from a single stem/progenitor cell, while the endocrine pancreas arises from multiple progenitors.     

Establishment of a novel method for the production of chimeric mouse embryos using water-in-oil droplets

Production of chimeric animals is often a necessity for the generation of genetically modified animals and has gained popularity in recent years in regenerative medicine for the reconstruction of xenogeneic organs. Aggregation and injection methods are generally used to produce chimeric mice. In the aggregation method, the chimeras are produced by co-culturing embryos and stem cells, and keeping them physically adhered, although it may not be an assured method for producing chimeric embryos. In the injection method, the chimeras are produced by injecting stem cells into the zona pellucida using microcapillaries; however, this technique requires a high degree of skill. This study aimed to establish a novel method for producing chimeric embryos via water-in-oil droplets that differs from conventional methods. In this study, embryonic stem cells and embryos were successfully isolated in the droplets, and the emergence of chimeric embryos was confirmed by co-culture for 6 h. Using this method, the control and operability of stem cell numbers could be regulated, and reproducibility and quantification were improved during the production of chimeric embryos. In addition to the conventional methods for producing chimeric embryos, the novel method described here could be employed for the efficient production of chimeric animals.     

Persistence of the developmental block of in vitro fertilized domestic cat embryos to temporal variations in culture conditions

A series of studies examined the influence and temporal interaction of energy substrate, media complexity, and tissue co-culture on the development of in vitro fertilized cat embryos and the persistence of the morula-to-blastocyst developmental block. In Study I, oocytes were fertilized and cultured for 144 hr in a simple culture medium (modified Krebs Ringer bicarbonate; mKrb), containing either glucose or glutamine, or cultured in mKrb w/ glutamine for the initial 72 hr with transfer to mKrb w/ glucose for the final 72 hr. Fertilization rate, percent development to morulae, and cell number per embryo were similar (P > 0.05) between treatments and blastocyst formation was universally low (<10%). In Study II, oocytes were fertilized and cultured in either mKrb (w/ glucose or glutamine) or in a complex medium, Ham's F10 (w/ 10% fetal bovine serum [FBS]). After 72 hr of initial culture, embryos in mKrb were transferred into Ham's F10. Fertilization rate was lower (P < 0.01) in Ham's F10 but embryo development to the morulae stage and cell number per embryo were comparable (P > 0.05) for all treatments. A higher percentage of blastocysts and morulae becoming blastocysts were observed after initial culture in mKrb w/ glutamine than after initial culture in mKrb w/ glucose. In Study III, oocytes were fertilized and cultured initially in mKrb (w/ glutamine), and then switched to either Ham's F10 or cat oviductal cell monolayers (in Ham's F10). Additional embryos were cultured exclusively in Ham's F10 or on cat oviductal cell monolayers. Fertilization rates were lower (P < 0.05) on oviductal cells but cell number per embryo was similar (P > 0.05) in all treatments. Blastocyst formation was lower (P < 0.05) on oviductal cells than in mKrb-Ham's F10 treatment and was <20% in all treatments. In summary, while in vitro fertilization-derived cat embryos develop to morulae under a variety of culture conditions, the morula-to-blastocyst developmental block was minimally responsive to alterations in energy substrate and medium complexity or fluctuations in their temporal availability. In addition, oviductal cell culture, alone or in combination with other culture variations, was ineffective in overcoming the developmental block. © 1996 Wiley-Liss, Inc.     

不同培养体系对鼠-猪异种嵌合胚胎发育和嵌合能力的比较

近年来,随着干细胞分化与再生医学研究的不断深入,异种嵌合已成为当前干细胞和再生医学领域的热点问题,并有望为未来解决器官移植供体来源严重短缺等再生医学难题开辟新的方向。异种嵌合以及异种器官再造过程中面临众多科学问题和技术难题,而异种嵌合过程中嵌合胚胎时期的选择,后续培养液的选择以及这些环节所造成的供体细胞与受体胚胎之间的发育平衡成为建立异种器官再造的第一个科学问题。猪由于具有与人类器官大小相似、繁殖快等特点,成为异种嵌合最适合的潜在研究对象。为了提高鼠-猪异种嵌合胚胎中小鼠供体细胞——诱导多潜能干细胞(Induced pluripotent stem cells,i PSCs)的存活率和增殖率,我们尝试以i PSCs培养液(N2B27)以及N2B27→PZM-3梯度更换的培养液(N2B27(3.5 h))作为研究异种嵌合胚胎体外发育培养的对象,并与猪胚胎培养液(PZM-3,Porcine zygotic medium)体系下发育进行比较,从而评价了这3种培养液在8-细胞和囊胚期注射后,对嵌合胚胎后续发育的影响及嵌合情况。结果显示,8-细胞期注射后,PZM-3不仅对嵌合胚胎的后续发育较为有利,更有利于小鼠i PS嵌合到猪胚胎中;囊胚期注射后3种培养体系下GFP阳性嵌合率差异不显著,但其嵌合率显著低于8-细胞期嵌合率。结果表明,PZM-3培养体系更有利于鼠-猪异种嵌合胚胎的体外发育,对8-细胞期胚胎进行嵌合操作有益于提高鼠-猪异种嵌合后胚胎的嵌合率。     

小鼠ES细胞种系嵌合体的获得

种系嵌合体的获得是实现ＥＳ细胞介导的转基因途径的决定步骤,ＥＳ细胞种系分化能力的保持是决定种系嵌合的前提条件,而事体的主种系嵌合体的获得则是判定ＥＳ细胞系是否具有种系分化能力的唯一方法,为考察本室新近建立的３种小鼠ＥＳ细胞系ＭＥＳＰＵ２１．ＭＥＳＰＵ２２和ＭＥＳＰＵ２９的种系分化能力,选用近交系Ｃ５７ＢＬ／６Ｊ及远交系ＫＭＷ和ＩＣＲ为受体胚胎提供者,分别通过囊胚注射法和８细胞期桑椹胚注射法进行了嵌     

褐家鼠精母细胞中联会复合体的研究Ⅳ.常染色体联会复合体的发育和偶线期节的研究

采用表面铺展－SDS处理、硝酸银和磷钨酸(Phosphotungstic acid,PTA)染色电镜技术,研究了褐家鼠精母细胞中常染色体联会复合体（Synaptonemal complex, SC）的发育及偶线期节（Zygotene nodule, ZN）。在褐家鼠精母细胞的细线期,常染色体轴心（Axial cores, ACs ）已形成,同源轴心在空间上靠近,偶线期SCs 开始形成,到粗线期SCs 完全形成,于双线期SCs 开始解体。在双线期除了个别SCs 侧生组分分开外,大多数SCs 发生碎片化（fragmentation）。在偶线期未配对的ACs 和SCs 侧生组分及中央组分上均发现电子密度高的球形或椭圆形的节状结构――偶线期节,ZNs 在同源染色体配对过程中起很重要的作用。 Abstract　Zygotene nodules(ZNs) and development of the brown ratRattus norvegicus caracohave been studied, by surface spresding with SDS treatment, silver and phosphotungatic acid(PTA) staining techniques. The results as follows: Chromosomal axial cores(ACs) formed during leptotene nuclei in spermatocytes of the brown rat, some homologous axial cores were close to each other. The fomation of SCs starts at zygotene, completed at pachytene and disintegrates at diplotene. In diplotene, lateral elements of a few SCs separate and the presence of fragmented SCs takes place. During zygotene on unpaired ACs and lateral elements and central elements of SCs, there are dense spherical or elliptical nodules-zygotene nodules(ZNs). They play an important part in the process of homologue pairing.     

前列腺癌的靶向治疗研究现状与展望

前列腺癌难以根治,研究雄激素非依赖型前列腺癌的靶向治疗具有实际的临床意义,涉及抗体靶向治疗、靶向抗前列腺癌药物研制、细胞生长信号转导通路抑制、微小RNA应用等多方面,而靶向清除肿瘤干细胞则是根治前列腺癌的有效策略。