电激活对完全体外化牛细胞核移植的影响

牛卵母细胞在体外成熟２３～２４ｈ时去核，去核卵用８０Ｖ／ｍｍ４０μｓ两次电脉冲激活（Ⅰ组）或不激活（Ⅱ组），然后将体外受精、发育的８～３２细胞期胚胎的单个卵裂球注入卵周隙，用８０Ｖ／ｍｍ４０μｓ两次电脉冲诱导卵裂球与去核卵母细胞融合。Ⅰ组操作后存活率和融合率（８８．４％和５５．０％）显著低于Ⅱ组（９５．９％和６５．１％，Ｐ＜０．０５）。融合卵体外培养２４ｈ和５～８ｄ后，Ⅰ组核移植胚胎的卵裂率和桑椹／囊胚发育率（６３．０％和１５．２％）与Ⅱ组（５０．５％和７．８％）无显著差异，但Ⅰ组结果均好于Ⅱ组。将来自两组的２５枚桑椹和囊胚移植到１６头同期受体，在已检查过的８头受体中２头受体妊娠，其中１头于妊娠后４个多月流产，１头于妊娠期满后产出一雄性牛犊。研究结果表明：去核卵母细胞的电激活尽管对重组卵的存活与融合不利，但可改善核移植胚的卵裂和发育。本研究在我国首次获得牛细胞核移植的成功，证明用ＩＶＭ卵母细胞和ＩＶＦ胚胎进行完全体外化的牛细胞核移植是可行的。     

小鼠皮肤成纤维细胞的体细胞核移植

取成年小鼠唇部皮肤进行培养，分离成纤维细胞并血清饥饿培养1周，用作核供体。对成年小鼠进行超排，取卵母细胞用作核受体，核移植重构胚经SrCl2激活处理6h后，同mM16培养液和小鼠输卵管上皮细胞共培养，把发育到早期囊胚的重构胚转移至小鼠胎儿成纤维细胞饲养层上，添加ES细胞条件培养液，消化分离ICM，然后接种培养，对孵出的ES细胞样集落进行鉴定培养。结果显示，小鼠唇部皮肤成纤维细胞为核供体，核移植重构胚2-细胞率为54．05％，桑椹胚率17．14％，囊胚率6．90％，对照组卵丘细胞的核移植重构胚2-细胞率为60．00％，桑椹胚率21．85％，囊胚率11．69％，但2种供体细胞在支持核移植重构胚发育能力上差异不显著。成纤维细胞重构囊胚中6个囊胚分离出ES细胞样集落，3个ES细胞样集落可稳定传代；对照组卵丘细胞重构囊胚中9个囊胚中分离出ES细胞样集落，5个ES细胞样集落可稳定传代。从核移植重构胚中分离出的ES细胞样集落具有岛状或巢状群体生长形态，生长旺盛的集落可自发分化成单个散在或片状存在的上皮样或梭形细胞，碱性磷酸酶检测为阳性，常规冻存复苏，仍显示ES细胞特征。     

兔核移植胚胎的克隆研究

本研究改进了兔受体卵母细胞的去核程序及供体卵裂球的处理方法，并对核移植胚的体外克隆、继代克隆及克隆胚的体内发育进行了试验。结果表明：卵龄对受体卵母细胞的去核具有显著的影响，卵龄为１５～１８ｈ的去核率为１００％（４５／４５），显著高于１３～１４ｈ的４６．６％（７／１５），Ｐ＜０．０１。ＤＮＡ合成抑制剂Ａｐｈｉｄｉｃｏｌｉｎ处理１６－细胞期卵裂球后，重组胚的囊胚发育率５４％（２０／３７）高于未处理组的４５％（１４／３１），Ｐ＜０．０５。从２枚１６－细胞供体胚分别获得来自一个供体胚的９枚和７枚核移植克隆囊胚，囊胚发育率为５１．６（１６／３１）。然而第一次继代核移植胚的囊胚发育率仅为１１．５％（６／５２）。１６－及３２－细胞期卵裂球的重组胚可发育至产仔，共获２窝８只仔兔。其中１只、２只、２只和３只仔兔分别来自４个供体胚。     

牛胚胎体外生产技术的简化研究

利用屠宰牛卵巢分离的卵母细胞，以卵裂率和囊胚发育率为标准，对牛胚胎体外生产过程进行了简化试验。结果显示：不加卵丘细胞的高密度卵母细胞体外成熟（１００～２００枚／平皿）可代替加卵丘细胞的标准密度（５０枚／平皿）培养，其卵裂率（５７．６％比６２．５％）和囊胚发育率（２３．７％比２９．１％）没有显著差异（Ｐ＞０．０５），体外授精时间可从成熟培养后２２ｈ延长至２７ｈ，卵裂率和囊胚发育率均没有显著变化，卵母细胞体外成熟后可以不经洗涤直接移入受精滴，原成熟培养皿内残留卵丘细胞再培养４８ｈ形成的单层细胞，可代替标准方法制作的单层小滴用于体外受精胚胎的共同培养，供胚胎发育培养的单层细胞使用多次不影响囊胚发育率，经简化的ＩＶＦ技术获得的胚胎非手术移入情期同步受体牛子宫角２～２．５个月后直检有５８．３％（７／１２）妊娠。我们认为，传统的牛胚胎体外生产技术经过简化可以提高生产效率，不会减少囊胚发育率和妊娠率，值得推广应用。     

昆明小鼠内细胞团和滋胚层细胞注入去核2-细胞胚的核移植研究

采用核移植技术将单个细胞注入去核2-细胞卵裂球中,比较来自于囊胚的内细胞团(ICM)和滋胚层细胞(TE)产生孕体或嵌合体的发育潜力。用TE和ICM重构胚胎的发育潜力,主要取决于注射hCG后从输卵管收集到的2-细胞胚胎的时间。在注射hCG后38～42 h和43～46 h收集得到的2-细胞胚胎,其重构胚胎仅仅能够发育到4-细胞期。注射hCG后48～51 h收集得到的2-细胞胚胎,重构后发生卵裂的胚胎比率显著提高,有少部分会发育到囊胚期。用诺考达唑(Nocodazole)处理这些重构胚,发生卵裂的胚胎比率会显著提高,并且有部分重构胚发育到囊胚阶段。将这些囊胚移植到受体鼠中,在其妊娠中期未检测到供体核的出现。用ICM和TE进行重构得到的嵌合2-细胞胚胎,其体外发育潜力有限,本试验中也未得到嵌合孕体。     

牛体外受精胚胎衍生干细胞能力影响因素的研究

以牛卵巢卵母细胞体外受精获取囊胚期胚胎，比较体外受精牛胚胎不同获取内细胞团的方法和不同培养液对体外培养胚胎干细胞能力的影响。结果表明，囊胚期胚胎不除去透明带而直接培养产生胚胎干细胞，初次克隆率为55％；胰酶法去透明带分离的内细胞团（ICM）培养产生胚胎干细胞，初次克隆率为90％。免疫外科法去透明带分离的ICM在4种不同的培养液中，初次克隆率分别为16．4％、11．5％、21．8％、18．2％，但是其分离的ICM经传代后形成的衍生细胞不易发生分化，经过4～6代的传代，仍然保持其完整的形态，说明免疫外科法是一种理想的牛ICM分离法，培养液为D20＋LIF（40ng／mL）可用于牛胚胎干细胞培养。     

水牛原生殖细胞核移植的研究

以水牛原生殖细胞（PGCs）为核供体,成熟水牛卵母细胞为受体,采用电融合法和胞质内直接注核法对水牛PGCs的核移植进行了研究。从水牛胎儿的生殖嵴或生殖腺分离得到PGCs,在胎儿成纤维细胞饲养层上传代培养后,进行核移植。结果显示,当采用电融合法时,PGCs核移植的融合率、分裂率、囊胚率和总囊胚率均显著高于胎儿成纤维细胞（P〈0．05）;当采用直接注核法进行核移植时,PGCs的核移植囊胚率显著高于胎儿成纤维细胞（P〈0．05）。但分裂率差异不显著（P〉0．05）。结果表明,水牛PGCs细胞是理想的核移植供体细胞。     

黑萨福克和杜泊羊新鲜和冷冻胚胎移植效率的研究

为提高优质肉用种用绵羊胚胎移植的效率,试验选取76只黑萨福克羊和27只杜泊羊作为供体,采用"CIDR+FSH+PMSG"法进行超数排卵处理。选取384只小尾寒羊为受体,采用"CIDR+PMSG"法进行同期发情处理,以探索供体胚胎发育阶段、胚胎冷冻处理、胚胎体外停留时间以及移植给受体时移植侧黄体数量等因素对胚胎移植妊娠率的影响。结果表明:移植新鲜囊胚的妊娠率极显著高于桑椹胚(P0.01);冷冻/解冻囊胚移植妊娠率极显著低于新鲜囊胚(P0.01),而冷冻/解冻桑椹胚移植妊娠率与新鲜桑椹胚无显著差异(P0.05);此外,移植桑椹胚时,移植侧有1个黄体的受体妊娠率极显著低于有2~3个黄体受体妊娠率(P0.01),但移植囊胚时两者间差异不显著(P0.05)。综上可知,子宫角移植桑椹胚和囊胚时,移植新鲜囊胚、移植冷冻桑椹胚效率较高;将新鲜桑椹胚移植给移植侧有2~3个黄体受体效果好于1个黄体受体。     

核移植前激活受体卵子对牛核移植卵体外发育的影响

本研究探讨了核移植前对受体卵子进行激活、细胞融合开始时间及供体受精卵细胞周期调节对核移植卵体外发育的影响。其结果显示核移植前对受体卵子激活组的细胞融合率与对照组没有差异 ,但重组胚胎的卵裂率、8～ 16细胞期胚胎及囊胚的发育率比对照组明显提高 ;核移植前激活的受体卵子分别在卵子体外成熟开始的第30h和 4 5h与供体细胞进行细胞融合 ,结果 ,30h组的细胞融合率和卵裂率与 4 5h组没有差异 ,但发育到 8～ 16细胞期及囊胚的发育率均比 4 5h的高 ;将供体受精卵用诺考达唑 (Nocodazole)处理后 ,进行核移植的结果 ,处理组的细胞融合率、卵裂率、发育到 8～ 16细胞期和囊胚的发育率与对照组无差异     

水牛体细胞核移植的研究

系统探讨了水牛体细胞核移植的各种影响因素，并初步建立了水牛体细胞核移植的一整套程序。体外成熟培养22～24h的水牛卵母细胞去核后，将经血清饥饿(0.5％FBs)培养2～9d、0．1mg／L Aphidicolin(APD)培养 0．5％FBs培养2～9d或一般培养法(10％FBS)培养的水牛耳皮成纤维细胞或颗粒细胞，直接注射到去核的卵母细胞质中，或注射到卵周隙中再经电融合(100V／mm，15μs，电脉冲3次)构建重构胚。重构胚经化学激活后(5pmol／L离子霉素5min，2mmol／L6-DMAP3h)培养7～8d，评定其胚胎发育能力。耳皮成纤维细胞和颗粒细胞经0．1mg／L APD 0．5％FBs培养处理后的重组胚卵裂率，均极显著高于血清饥饿和一般培养处理的同种供体细胞(P＜0.01)，但囊胚发育率无显著差异(P＞0．05)。耳皮成纤维细胞和颗粒细胞经0.1mg／L APD 0.5％FBS处理后进行核移植的分裂率和发育率均无显著差异(63．06％比58．70％，P＞0．05)。以水牛颗粒细胞为核供体时，电融舍法的重构胚分裂率显著高于胞质内注入法(P＜0.05)，囊胚发育率无显著差异(P＞0.05)。培养3代和6代的水牛颗粒细胞以及培养6代和10代的耳皮成纤维细胞，其具有正常二倍染色体的细胞比例均无显著差异(P＞0.05)；以这2种细胞不同培养代数作供体进行核移植时，各代之间核移胚的体外分裂率、囊胚发育率无显著差异P＞0.05)。这些结果表明：(1)水牛耳皮成纤维细胞和颗粒细胞经培养传代所建立起来的细胞系相对比较稳定；(2)0.1mg／L APD预培养处理供体细胞能提高水牛体细胞核移植的效果，但血清饥饿培养则无作用；(3)水牛耳皮成纤维细胞和颗粒细胞均可作供核细胞，核移植后都能得到体细胞克隆的囊胚，但前者的效果略优于后者，且其核移植效果不受供核细胞培养代数的影响；(4)电融合核移植胚胎的发育率高于胞质内直接注入法，但两者的总体效率相似。     

转GFP基因核移植牛胚胎的研究

试验采用脂质体转染法与电穿孔法,以携带绿色荧光蛋白（GFP）-新霉抗性（neo-）双标记基因的pMSCV质粒转染胎牛耳成纤维细胞为供体与体外成熟的牛卵母细胞为受体构建克隆胚。研究了体外成熟培养液中添加EGF（表皮生长因子）对转基因胚的影响,不同转染方法构建供体细胞对重构胚发育的影响和在不同体外培养系统中的发育效果。结果显示,体外成熟培养液中添加EGF 30 ng/mL组的卵母细胞成熟率最高,但对后期转基因重构胚的囊胚发育率的影响,以添加EGF 20 ng/mL组的最高;以胎牛耳成纤维细胞为供体细胞,不同转染方法转染供体细胞构建重构胚,其囊胚发育率差异不显著（P>〖JP2〗0.05）;mSOFaa+颗粒细胞单层细胞共培养体系中的转基因囊胚发育率最好,该体系更适合体细胞核移植法生产转基因牛胚胎。     

In vitro development and postvitrification survival of cloned feline embryos derived from preadipocytes

The aim of the present study was to optimize the conditions for in vitro development and postvitrification survival of somatic cell cloned feline embryos. To determine the effects of cell cycle synchronization of the nuclear donor cells, we cultured preadipocytes under serum starvation or conventional conditions. After two days in serum starvation culture, the proportion of synchronized donor cells at the G0/G1 phase was 91.6%. This was significantly higher than the proportion of non-synchronized cells in the proliferative phase (72.6%, P<0.05). The in vitro development of somatic cell nuclear transfer (SCNT) embryos reconstructed using donor cells treated under serum starvation conditions (normal cleavage rate of 65.7%, 46/70, and blastocyst formation rate of 20.0%, 14/70) was comparable to that of the serum supplemented group (52.5%, 31/59, and 20.3%, 12/59). Use of in vitro or in vivo matured oocytes as recipient cytoplasts equally supported development of the SCNT embryos to the blastocyst stage (11.9%, 5/42, vs. 9.5%, 2/21). SCNT-derived blastocysts were vitrified using the original minimum volume cooling (MVC) or the modified (stepwise) MVC method. Although none (n=10) of the SCNT blastocysts survived following vitrification by the original MVC method, the stepwise MVC method resulted in 100% survival after rewarming (n=11). In conclusion, we demonstrated that feline somatic cell cloned embryos with a high developmental ability can be produced irrespective of cell cycle synchronization of donor cells using either in vivo or in vitro matured oocytes. Furthermore, by utilizing a stepwise vitrification method, we showed that it is possible to cryopreserve cloned feline blastocysts.     

Production of blastocysts after intergeneric nuclear transfer of goral (Naemorhedus goral) somatic cells into bovine oocytes

Interspecies cloning may be a useful method to help conserve endangered species and to study nuclear-cytoplasm interaction. The present study investigated in vitro development of goral (Naemorhedus goral) intergeneric nuclear transfer embryos produced by fusing goral fibroblasts with enucleated metaphase II (MII) bovine oocytes. After two to five passages, serum-starved or non-starved goral skin fibroblast cells were transferred into enucleated MII bovine oocytes. Couplets were electrically fused and chemically activated, and then cultured in either modified synthetic oviduct fluid (mSOF) or tissue culture medium-199 (TCM-199) supplemented with 10% FBS. Serum starvation of donor cells did not affect the fusion rate and or development to of cells to the two-cell stage, to more than 9-cells, or to morulae, regardless of culture medium. Three blastocysts from 202 fused embryos were obtained when embryos reconstructed with non- serum- starved donor cells were cultured in mSOF. However, no blastocysts were obtained when the embryos reconstructed with serum-starved donor cells were cultured in mSOF. The total cell number of goral intergeneric embryos averaged 130.3 (range 105-180). In conclusion, this study demonstrated that bovine oocytes can support blastocyst development after intergeneric SCNT with goral fibroblasts.     

The use of embryonic stem cell derived bioactive material as a new protein supplement for the in vitro culture of bovine embryos

Embryonic stem (ES) cells are expanded versions of the inner cell mass cells that compose the early mammalian blastocyst. Components derived from ES cells may contain various bioactive materials (BM) helpful for early preimplantation embryo growth. In this study, we examined the effect of human ES cell derived BM (hES-BM) on in vitro culture of bovine embryos. When bovine parthenogenetic day 2 embryos were cultured in 10% hES-BM, a significantly higher embryo development rate (44.3%) and increased cell numbers were observed relative to control medium containing 3 mg/ml BSA (19.5%; P<0.01). Among the various concentrations (5, 10 and 15%) and days of treatment (2 or 4 days) tested, 10% hES-BM treatment for 4 days provided the best culture environment to support the growth of bovine embryos in vitro (P<0.05). Little difference was observed between 10% hES-BM and 10% FBS treatment in the examined parthenogenetic or in vitro fertilized embryos, although the hES-BM group developed at a slightly better rate. However, the ICM cell numbers were significantly higher in the hES-BM group in irrespective of embryo origin (P<0.05). In addition, the relative levels of pluripotency (Oct4, × 1.8 fold; Nanog. × 3.3 fold), embryogenesis (Stat3, × 2.8 fold; FGF4, × 18.8 fold; E-cad, × 2.0 fold) and growth (Glut5, × 2.6 fold) genes were significantly higher in the 10% hES-BM group than in the 10% FBS group (P<0.05), while the levels of other genes (Bax, Bcl2, MnSOD and Connexin43) were not different. This is the first report examining the positive effects of hES-BM on bovine embryo development in vitro. Based on our results, we conclude that hES-BM can be used as a new protein supplement for bovine preimplantation embryo development.     

奶牛耳成纤维细胞的分离培养及培养条件的研究

本试验研究了奶牛耳成纤维细胞的体外培养,培养液、消化液、胰岛素和血清饥饿对细胞的影响。采用组织块贴壁法培养。了奶牛耳成纤维细胞,采用0．25％胰酶差别消化获得了纯化的奶牛耳成纤维细胞。用三种不同的培养液即DMEM（低糖）、DMEM（高糖）、DMEM／F12,对细胞进行培养,结果细胞群体倍增时间均在2．3-2．5d,DMEM（高糖）的培养效果稍好。用三种不同的消化液（0．25％胰蛋白酶,0.02％EDTA,0．25％胰蛋白酶＋0．02％EDTA）对传代钿跑进行消化．结果表明0．25％胰蛋白酶＋0D2％EDTA所用时间短,消化后培养细胞贴壁率高。在培养液中添加姨岛素能促进细胞的生长。对指数生长期的细胞进行血清饥饿后,细胞仍保持着较高的活力。     

Effect of zearalenone on the growth of mouse embryos from blastocysts to the egg cylinder stage in vitro

Embryos were harvested at the blastocyst stage from nontreated outbred mice and were grown in vitro for 4 days. Embryos cultured in control medium hatched and grew to the egg cylinder stage. Purified zearalenone (ZEN) added to the culture medium at concentrations of 8.5 to 68 micrograms/ml decreased the number of embryos growing, with a 50% decrease in the number growing in 32 micrograms of ZEN/ml of medium. Embryos growing in ZEN had decreased numbers of cells derived from the inner cell mass, normal growth of the trophoblast, less cellular differentiation than was seen in control embryos, and increased numbers of phagosomes. Undifferentiated cells of the inner cell mass of control and treated embryos were of the same size, as determined by morphometric analysis. Addition of 25 micrograms of estradiol/ml of culture medium caused no decrease in number of embryos growing or in embryonic size. Saturation of culture medium with ZEN (68 micrograms/ml) did not inhibit the growth of a tissue culture line of goat synovial cells. Seemingly, ZEN at concentrations near saturation inhibited the growth of mouse embryos in vitro. This effect was not duplicated with similar concentrations of estradiol and was not manifested in culture-adapted cells.     

Production of HanWoo (Bos taurus coreanae) fetuses following interbreed somatic cell nuclear transfer

The possibility of producing HanWoo (Bos taurus coreanae) calves from transferable bovine embryos, obtained by interbreed nuclear transfer using Holstein cytoplasts and surrogates, was investigated. As donor nuclei, HanWoo fetal fibroblasts were used. Cells were induced into quiescence by serum deprivation for 4-7 days before nuclear transfer. In vitro matured Holstein oocytes were enucleated, and single donor cell was placed into the perivitelline space of enucleated oocyte. After reconstruction, the embryos were fused. activated and cultured. On day 7, the embryos that developed to the blastocyst stages were transferred into Holstein recipient cows on day 6 to 7 of estrous cycle (estrus=0). The reconstructed embryos were successfully fused (58.8%; 47/80), cleaved (91.5%; 43/47), and developed to blastocysts (29.8%; 14/47). Eleven blastocysts were transferred into 5 Holstein recipient cows. Two recipients were pregnant, confirmed by ultrasonography at day 60 of gestation. But, one of them was opened between on day 80 to 100 of pregnancy, and the other had a stillbirth on day 255. The stillborn calf was physically normal, and we couldn't find any evidence of anomaly. These results show that cells derived from HanWoo somatic cell lines can be reprogrammed by interbreed nuclear transfer and develop subsequently in vivo as well as in vitro.     

Development of bovine embryos cultured in CR1aa and IVD101 media using different oxygen tensions and culture systems

The aim of the present study was to optimise the culture conditions for the in vitro production of bovine embryos. The development of in vitro fertilised bovine oocytes in CR1aa supplemented with 5% calf serum and IVD101 culture media were compared using traditional microdrops and Well of the Well (WOW) culture systems either under 5% or 20% oxygen tension. After 7 days of culture, a significantly higher blastocyst formation rate was obtained for embryos cultured in CR1aa medium compared to those cultured in IVD101, irrespective of O2 tensions and culture systems. The blastocyst formation in IVD101 was suppressed under 20% O2 compared to 5% O2 . Despite their similar total cell numbers, higher rates of inner cell mass (ICM) cells were observed in blastocysts developed in IVD101 medium than in those developed in CR1aa, irrespective of O2 tensions. There was no significant difference in blastocyst formation, total, ICM and trophectoderm (TE) cell numbers between embryos obtained by microdrop and WOW culture systems irrespective of the culture media and O2 tensions used. In conclusion, CR1aa resulted in higher blastocyst formation rates irrespective of O2 tension, whereas IVD101 supported blastocyst formation only under low O2 levels but enhanced the proliferation of ICM cells.     

Production of nuclear transfer embryos by using somatic cells isolated from milk in buffalo (Bubalus bubalis)

Somatic cells in milk are a potential source of nuclei for nuclear transfer to produce genetically identical animals; this is especially important in animals that are susceptible to risks of bacterial infection on biopsy collection. In this study, a minimum of 10 milk samples were collected from each of the three buffaloes representing Murrah breed. All the samples were processed immediately and cell colonies were obtained. Cell colonies from one buffalo (MU-442) survived beyond 10 passages and were evaluated by fluorescence microscopy and used in nuclear transfer experiments. In culture, these cells expressed vimentin, indicating they were of fibroblast origin similar to ear cells. We compared the effectiveness of cloning using those milk-derived fibroblast (MDF) cells and fibroblast cells derived from the ear derived fibroblast (EDF). Fusion and cleavage rates of MDF-NT and EDF-NT embryos were found to be similar (92.43 ± 1.28% vs 94.98 ± 1.24%, and 80.27 ± 1.75% vs 84.56 ± 3.73%, respectively; p > 0.01); however, development to blastocyst stage and total cell number was higher for EDF-NT embryos (50.24 ± 2.54%, 227.14 ± 13.04, respectively, p < 0.01), than for MDF-NT embryos (16.44 ± 0.75%, 170.57 ± 4.50 respectively). We conclude that somatic cells from milk can be cultured effectively and used as nucleus donor to produce cloned blastocyst-stage embryos.