基因组印迹的调控机制及其对动物克隆的影响

基因组印迹是一种表观遗传学调控方式.依据亲源性的不同机体仅表达来自亲本一方的等位基因,而来自另一方的等位基因不表达,这类基因称为印迹基因,印迹基因成簇存在,受该簇内的印迹控制区(imprinting Ccontrol region,ICR)调控.基于ICRS的功能,研究者提出两种模式解释基因组印迹的机制:绝缘体印迹模式和非编码RNA印迹模式,印迹基因的正确表达对哺乳动物的正常发育极为重要,错误的印迹会引起严重的遗传性疾病和癌症.克隆动物发育异常也可能与之相关.结合本研究组最近的研究,文中综述了基因组印迹的调控机制及其对动物克隆的影响.     

基因组印迹的调控机制及其对动物克隆的影响

基因组印迹是一种表观遗传学调控方式．依据亲源性的不同机体仅表达来自亲本一方的等位基因,而来自另一方的等位基因不表达,这类基因称为印迹基因．印迹基因成簇存在,受该簇内的印迹控制区（imprintingcontrolregion,ICR）调控．基于ICRs的功能,研究者提出两种模式解释基因组印迹的机制：绝缘体印迹模式和非编码RNA印迹模式．印迹基因的正确表达对哺乳动物的正常发育极为重要,错误的印迹会引起严重的遗传性疾病和癌症．克隆动物发育异常也可能与之相关．结合本研究组最近的研究,文中综述了基因组印迹的调控机制及其对动物克隆的影响．     

不同转移能力的人鼻咽癌细胞CNE-2Z克隆株在scid小鼠体内的验证和比较

报道将从人类鼻咽癌细胞系(CNE-2Z)分离出的不同克隆株细胞悬液,分别移植于严重联合免疫缺陷(scid)小鼠和BALB/c裸鼠的背侧皮下,于56天后处死所有小鼠,进行了大体和组织学检查。结果发现当每只scid小鼠移植2×10~6个瘤细胞时,CNE2-L2克隆株为高转移株,其淋巴转移率为100％,肺转移率为71％;而CNE2-L4克隆株为低转移株,其肺转移为13％,淋巴结未见转移;而当每只小鼠移植2×10~5个瘤细胞时,CNE 2-L2也为高转移克隆株,但比上者为低,其淋巴结转移率为71％。肺转移率为14％;CNE2-M2克隆株为中转移株。其淋巴转移率为43％,肺转移率为14％。与其裸鼠相比,当给每只BALB/c移植2×10~6个瘤细胞后56天时,尚未查见转移。说明两种免疫缺陷动物对恶性瘤细胞表型的表达,scid小鼠比BALB/c裸鼠为敏感。另外,皮下移植瘤细胞的数量也可能与转移出现的时间有密切关系。在相同时间内移植瘤细胞数越多,转移率也相对地增高,反之亦然。     

螟蛉和蜾赢的种间关系是什么,是捕食还是寄生?

<正>螟蛉有子,蜾赢负之这句话出自《诗经·小雅·小宛》。螟蛉,泛指稻螟蛉、棉铃虫、菜粉蝶等多种鳞翅目昆虫的幼虫。蜾赢,一类昆虫的通称,属于昆虫纲、膜翅目、胡蜂总科。蜾赢蜂捕螟蛉为食,并以产卵管刺入螟蛉体内,注射蜂毒使其麻痹,然后负之置于蜂巢内,作为蜾赢的幼虫的食料。古人错认为蜾赢养螟蛉为子。因而把螟蛉或螟蛉子作为养子的代称。生物之间的种间关系包括竞争、捕食、互利共生等。捕食是指一种生物以另一种生物作为食物。从广义上来讲,捕食包括以     

首席推销员卖的是什么? “领导人订单”,赔赚自知

领导人同时也是一个国家的首席推销员,出访国外却空手而回,对领导人来说是最大的耻辱,是无能的体现。尽管法国总统奥朗德以前从未来过中国,但在这次短短37个小时的访问里,他依然收获了丰厚的订单:中国航空器材集团公司和空客签署60架空客飞机订单;核能巨头阿海珐和法国电力与广东核能集团签署三方长期合作协议;甚至还得到了阿海珐和中国核工业集团签署建造核废料处理设施意向书。     

中国第一个获得美国FDA“突破性疗法”认证的抗癌新药,到底好在哪?

 2019年1月15日,美国食品和药物管理局（FDA）授予了一款在研的布鲁顿氏酪氨酸激酶（BTK）抑制剂泽布替尼（Zanubrutinib）突破性疗法认证,用于治疗先前接受至少一次疗法的成年套细胞淋巴瘤（MCL）患者,这也成为首个在FDA获得突破性疗法认定的中国自主研发抗癌新药。介绍了突破性疗法认证的定义,讲述了新型布鲁顿氏酪氨酸激酶抑制剂泽布替尼的特点,阐述了其对中国医药研发企业的意义。     

Q:试电笔的原理是什么?电流通过试电笔流到人体时,人体能否容纳电荷,不需要再流向大地?

正A:试电笔是判断照明电路中的火线和零线、检验低压电气设备是否漏电的常用而又方便的工具。典型的试电笔构造如图所示。氖管中充有稀薄的氖气,两端是两个金属电极。当电极间的电压达到一定值时,氖气电离导电,产生辉光反应,发出红光。使用时,手指按住试电笔末端的金属笔卡或金属帽,用笔尖接触被测的导线,如果氖管发光,即说明被测导线为火线,或被测设备带电。     

《语言机能》述评——《语言机能:是什么,谁拥有,如何进化的?》述评

本文总结了HCF《语言机能》一文的主要内容,包括对语言机能的理解需要学科间的合作;对狭义和广义语言机能的区分;FLN为人类特有;语言的对比研究方法等。另外,本文还对HCF的观点予以简短的评价。     

人体温度为什么要保持在37℃,这是如何做到的?

<正>A:人是恒温动物,不论周围环境的温度是高至50℃,还是低至-40℃,正常人的体温都保持在37℃左右。许多科学家认为,人体在37℃时,体内大多数酶的活性最高,这样能够维持机体正常的新陈代谢。还有的科学家推测,体温在37℃时,机体维持体温恒定所需要吸收或散发的热量较少,这在一定程     

兴奋在神经纤维上的传播是双向的,但是实际上似乎只需单向传播就行了。双向传播对人体有什么意义?

正神经纤维是神经细胞的突起,包括轴突和树突。而兴奋的本质是动作电位。对神经细胞来说,兴奋是树突接受刺激后诱发细胞体与轴突连接处的轴丘(轴突起始段)形成动作电位而产生的。动作电位产生后的确是双向传播的,一方面向轴突末端传播,此过程并     

Effects of different nuclear transfer and activation methods on the development of mouse somatic cell cloned embryos

A group of adult somatic cell cloned mice were obtained by using cumulus cells as nuclei donor cells. To study the effect of different nuclear transfer (NT) and activation methods on the development of mouse cloned embryos, embryos were reconstructed using two traditional NT methods (electrofusion and direct injection) and four activation treatments (electric pulse, ethanol, SrCl2 and electric pulse combined with SrCl2). The data showed that the efficiency of reconstruction using the direct injection method is significantly higher (90.7%) than that of the electrofusion method (49.7%). Parthenogenetic embryos can develop to blastocyst stage with three activation conditions, including ethanol, electric pulse and SrCl2; however, the rates of development to blastocyst after ethanol and electric pulse acti-vation (52.4%, 54.2%) are significantly lower than after SrCl2 activation (76.9%). Treatment of embryos for 6 h with 10 mmol/L SrCl2 was found to be the best condition for activation of parthenogenetic as well as reconstructed embryos. By contrast, reconstructed embryos failed to develop to blastocyst stage after being activated by ethanol. The use of either injection or electrofusion for embryo reconstruction affected the pre-implantation development. However, after transfer in pseudopregnant mice, cloned mice were obtained from both methods.     

Aberrant DNA methylation in cloned ovine embryos

By using the approach of immunofluorescence staining with an antibody against 5-methylcytosine （5MeC）, the present study detected the DNA methylation patterns of cloned ovine embryos. The embryos derived from in vitro fertilization were also examined for reference purpose. The results showed that： （1） during the preimplantation development, cloned embryos displayed a similar demethylation profile to the fertilized embryos; that is, the methylation level decreased to the lowest at 8-cell stage, and then increased again at morulae stage. However, methylation level was obviously higher in cloned embryos than in stage-matched fertilized embryos, especially at 8-cell stage and afterwards; （2） at blastocyst stage, the methylation pattern in cloned embryos was different from that in fertilized embryos. In cloned blastocyst, inner cell mass （ICM） exhibited a comparable level to trophectoderm cells （TE）, while in in-vitro fertilized blastocyst the methylation level of ICM was lower than that of TE, which is not consistent with that reported by other authors. These results indicate that DNA methylation is abnormally reprogrammed in cloned embryos, implying that aberrant DNA methylation reprogramming may be one of the factors causing cloned embryos developmental failure.     

哺乳动物克隆的现状和研究进展

 哺乳动物细胞克隆是20世纪末生命科学领域最引人注目的高新技术,该技术对于优良种畜的复制、减少试验用动物数目、动物遗传多样性保存及濒危动物挽救、转基因动物培育等方面具有重要意义。近年来克隆技术发展迅速,多种哺乳动物相继克隆成功,但也存在克隆效率太低、克隆动物表型正常而实质异常的问题。本文详细阐述了克隆效率太低、克隆动物表型正常而实质异常问题,介绍了当前动物克隆技术的发展现状,并对动物克隆涉及的技术进行了总结和概括,着重介绍了卵母细胞的去核方法和重组胚的构建方法。     

Effects of different nuclear recipients on developmental potential of mouse somatic nuclear transfer embryos

Somatic cell nuclear transfer has been succeeded in procedures of nuclear transfer. One is single nucleartransfer, the other is serial nuclear transfer. Viable animals have been cloned in different species using both me-thods[1—6]. Different nuclear recipients and donors wereused in serial nuclear transfer, namely, transferring thenuclear of reconstructed embryo into enucleated MⅡoocytes[7], transferring the nuclear of reconstructed em-bryos at one cell stage into enucleated zygote[4] and t…     

Clone of Chinese Jinan red-cross yellow cattle and evaluation of reproductive characteristics of cloned calf

Somatic cell clone technology is a viable approach to preserving endangered livestock and wildlife genetic resources. In the present research, somatic cell nuclear transfer （SCNT） was performed using granulose cells from the critical endangered Chinese red-cross yellow cattle as donor cells. A total of 211 oocytes were manipulated and 166 （79%） of them were successfully enucleated. 112 （67.4%） SCNT embryos were reconstructed, 94 （83%） of them cleaved, and 48 （43 %） of them developed to blastocyst stage. SCNT blastocysts were transferred to 6 Holstein recipients, and 2 （33%） of them were found to be pregnant. One of them maintained to term and delivered a calf, whereas another aborted. Effect of different fusion buffer （mannitol vs. Zimmerman fusion buffer） and different activation methods （calcium ionophore＋6-DMAP vs. cycloheximide＋CB） on fusion rate and development of SCNT embryos were investigated. The results indicated that： （i） on condition of two DC pulses of 2.5 kV/cm for 10 μs each, fusion rates were higher in mannitol solution than in Zimmerman fusion buffer （71% vs. 61%, respectively, p 〈 0.05）, but the blastocysts rates did not differ between two treatments （36 % vs. 39 %, p〉0.05 ）; （ii） There was no significant difference in development rates to the blastocyst stage for SCNT embryos activated by calcium ionophore＋6-DMAP or by cycloheximide＋CB （42% vs. 46%, respectively, p〉0.05）. Microsatellite DNA analysis examining 28 loci confirmed that the cloned calf was genetically identical to the donor Jinan red-cross yellow cattle and different from the recipient females. Growth and reproductive performance of cloned cow were evaluated, and there were no difference i cross-red n it between cloned and normal control Jinan yellow cattle. Furthermore, the cloned yellow cow has delivered a healthy yellow calf.     

DNA methylation status of H19 and Xist genes in lungs of somatic cell nuclear transfer bovines

In somatic cell nuclear transfer (SCNT) technologies,the donor cell’s nuclei need to be epigenetically reprogrammed for embryonic development. The incomplete reprogramming of donor cell nuclei has been implicated as a primary reason for the low efficiency of SCNT. DNA methylation is a major epige-netic modification of the genome that regulates crucial aspects of genome function,including estab-lishment of genomic imprinting. In order to make sure whether the DNA methylation reprogramming is efficient in SCNT animals,we analyzed the DNA methylation status of two imprinting genes,H19 and Xist,in lungs of deceased SCNT bovines that died within 48 h of birth using bisulfite sequencing analysis. Our findings demonstrated that cloned bovines showed significantly lower DNA methylation of H19 than controls (P<0.05),and three tested CpGs sites (1,2,3) exhibited unmethylation in one cloned bovine (9C3); however,Xist showed similar DNA methylation levels between clones and con-trols,and both showed hypermethylation (96.11% and 86.67%).     

用于“治疗性克隆”人胚胎干细胞研究面临的问题与可能的解决办法

利用培育的干细胞(SC)来实现组织再生和器官修复对于许多重大疾病如糖尿病、心脏疾病、老年性痴呆(AD)、帕金森病(PD)、神经损伤等的治疗具有重要意义,同时也是新药研发的重要工具.使用体细胞核转移技术(SCNT)克隆人类早期胚胎和提取干细胞,即所谓的"治疗性克隆"(Therapeutic cloning)技术,是目前进行干细胞个性化治疗的重要手段,具有广泛的临床应用前景.通过这种方法获得人胚胎干细胞的研究尚处于基础阶段,仍面临着许多有待解决的科学问题和技术挑战.在此主要就用于"治疗性克隆"人胚胎干细胞的研究进展做了简要综述,着重探讨了在该研究领域面临的主要困难,特别是在获得人成熟卵细胞方面,并提出了可能的解决办法.     

Production of transgenic calves by somatic cellnuclear transfer

Bovine fetal oviduct epithelial cells were transfected with constructed double marker selective vector(pCE-EGFP-IRES-Neo-dNdB) containing the enhanced green fluorescent protein (EGFP) and neomycin-resistant(Neo^r) genes by electroporation, and a transgenic cell line was obtained. Somatic cell nuclear transfer (SCNT) was cartied out using the transgenic cells as nuclei donor. A total of 424 SCNT embryos were reconstructed and 208 (49.1%) of them developed to blastocyst stage. 17 blastocysts on D 7 after reconstruction were transferred to 17 surrogate calves,and 5 (29.4%) recipients were found to be pregnant. Three of them maintained to term and delivered three cloned calves.PCR and Southern blot analysis confirmed the integration of transgene in all of the three cloned calves. In addition, expression of EGFP was detected in biopsy isolated from the transgenic cloned calves and fibroblasts derived from the biopsy. Our results suggest that transgenic calves could be efficiently produced by SCNT using transgenic cells as nuclei donor. Furthermore, all cloned animals could be ensured to be transgenic by efficiently pre-screening transgenic cells and SCNT embryos using the constructed double marker selective vector.     

Reconstruction of human embryos derived from somatic cells

Reconstruction of human nuclear transfer embryos is a necessary step of therapeutic cloning. In this study we injected somatic cell nuclei into M Ⅱ oocytes and activated reconstructed oocytes with calcium ionophore A23187 (CaA) and 6-dimethylaminopurine (6-DMAP). After oocyteactivation and 2PN formation, we removed the female PN.By using this method, we avoided the application of DNA fluorescent stain and ultraviolet light for oocyte enucleation,and over elimination of ooplasm was also mitigated. Some reconstructed embryos developed into the blastocyst stage in vitro.     

Nuclear reprogramming by nuclear transplantation and defined transcription factors

In the past ten years, great breakthroughs have been achieved in the nuclear reprogramming area. It has been demonstrated that highly differentiated somatic cell genome could be reprogrammed to a pluripotent state, which indicates that differentiated cell fate is not irreversible. Nuclear transplantation and induced pluripotent stem (iPS) cell generation are the two major approaches to inducing reprogramming of differentiated somatic cell genome. In the present review, we will summarize the recent progress of nuclear reprogramming and further discuss the potential to generate patient specific pluripotent stem cells from differentiated somatic cells for therapeutic purpose. Supported by the National High Technology Research and Development Program of China (Grant No. 2005AA210930)