Cloned pigs produced by nuclear transfer from adult somatic cells

Since the first report of live mammals produced by nuclear transfer from a cultured differentiated cell population in 1995 (ref. 1), successful development has been obtained in sheep, cattle, mice and goats using a variety of somatic cell types as nuclear donors. The methodology used for embryo reconstruction in each of these species is essentially similar: diploid donor nuclei have been transplanted into enucleated MII oocytes that are activated on, or after transfer. In sheep and goat pre-activated oocytes have also proved successful as cytoplast recipients. The reconstructed embryos are then cultured and selected embryos transferred to surrogate recipients for development to term. In pigs, nuclear transfer has been significantly less successful; a single piglet was reported after transfer of a blastomere nucleus from a four-cell embryo to an enucleated oocyte; however, no live offspring were obtained in studies using somatic cells such as diploid or mitotic fetal fibroblasts as nuclear donors. The development of embryos reconstructed by nuclear transfer is dependent upon a range of factors. Here we investigate some of these factors and report the successful production of cloned piglets from a cultured adult somatic cell population using a new nuclear transfer procedure.     

Patterns of junctional communication in the early amphibian embryo

It has long been recognized that cells in early embryos can communicate with each other via a direct cell-to-cell pathway, probably mediated by gap junctions. Low electrical resistance pathways, detected electrophysiologically, have been identified in all species examined so far. However, studies in various embryos on the transfer of molecules larger than small ions (for example, fluorescent dyes in the molecular weight range 350-500) have given conflicting results. In all these studies the ability to transfer dyes from cell to cell was determined without reference to the position of the injected cell in the embryo. In the experiments reported here, cell-cell transfer of the fluorescent dye, Lucifer yellow (molecular weight (Mr) 450) was re-examined in the early Xenopus laevis embryo by injecting the dye into identified cells, as the position of the injected cell within the embryo may be important. At the 32-cell stage, we found that dye transfer often occurred between animal pole blastomeres which were not sisters, as well as between sister cells, and also that Lucifer yellow was indeed transferred via gap junctions. The cell-cell transfer was not uniform within the animal pole; transfer was maximal near the dorsal side and minimal at the ventral side. This pattern may reflect differences in permeability or numbers of gap junctions across the embryo, and could be related to early events in development.     

山羊传染性胸膜肺炎的临床诊疗

分析了某羊场发生山羊传染性胸膜肺炎的发病情况、临床症状、解剖变化，针对山羊胚胎移植手术前后的临床表现，提出了山羊传染性胸膜肺炎的预防治疗方案，使该群羊的发病、死亡率得到了有效制，提高了羊胚胎移植的成活率。     

贵州新元古代瓮安生物群中动物胚胎化石研究进展

 瓮安生物群指产出于贵州瓮安磷矿地区新元古代埃迪卡拉纪陡山沱组（635~551Ma）上磷矿段的一个特殊磷酸盐化微体化石组合,主要由多细胞藻类、大型带刺疑源类和处于不同发育阶段的多种后生动物胚胎组成,并包括少量可能的后生动物幼虫和成体化石。瓮安生物群作为迄今为止世界上最古老的前寒武纪后生动物化石群,为探索后生动物的起源和早期演化历程提供了独一无二的实证记录。10余年来,瓮安生物群中动物胚胎化石的研究取得多项突破性进展,已确认至少5种不同卵裂方式的动物胚胎化石,胚胎化石分类从单纯的形态学分类向生物学分类转变,为揭示瓮安生物群中动物多样性提供了更多线索。同时,相关研究更新了繁盛于埃迪卡拉纪大型带刺疑源类生物属性的传统认识,并将之与有表面装饰的动物休眠卵（滞育胚胎）化石相联系。同步辐射X射线显微CT技术的应用成功解决了胚胎化石三维无损成像难题,为古胚胎学的发展带来了新的机遇。     

国产试剂配制的培养液对小鼠早期胚胎培养效果的研究

本实验用 Whitten 的小鼠早期胚胎培养法验证了国产试剂配制培养液对小鼠早期胚胎体外培养的效果。实验表明,在用国产试剂配制的小鼠早期胚胎培养液中,2—细胞胚胎能正常发育到囊胚阶段。     

静电场对小鼠胚胎发育能力的影响

首次报道哺乳动物胚胎经静电场处理后对＂细胞阻滞＂和后期发育能力的影响．结果表明，用静电场处理小鼠体外受精卵和２细胞胚胎时，对克服小鼠＂２细胞阻滞＂无显著影响．处理发育于Ｍ１６＋１００μＭＥＤＴＡ＋输卵管上皮的２细胞胚胎时，显著提高了胚胎的发育能力，最佳处理剂量的囊胚率从４２％提高到６４％，囊胚孵化率从２０％提高到４５％．     

复合驱羊蠕虫药物对建昌黑山羊和绵羊增重影响的研究

本试验主要测定“晴天”、“体内外驱虫一次净”应用于羊蠕虫病感染羊驱虫后对建昌黑山羊生长和增重的影响,结果表明,这两类药物应用于羊蠕虫病感染羊驱虫后对羊只的生长发育有较好的促进作用,建昌黑山羊和绵羊试验组分别比对照组净增重5.72kg/只和5.36kg/只(平均增重5.54kg),增重效果显著。     

Human pregnancy following cryopreservation, thawing and transfer of an eight-cell embryo

The widespread use of clomiphene citrate and exogenous gonadotrophins for in vitro fertilization (IVF) in human frequently results in the production of multiple embryos. Replacement of more than two embryos increases pregnancy rate but may result in multiple pregnancies with increased pre- and post-natal abnormality. Preservation of embryos for a limited time allows fewer embryos to be replaced on several different occasions and thus the problems of multiple pregnancy can be minimized, the effectiveness of a single IVF procedure increased and embryo replacement in adverse maternal conditions avoided. Preimplantation embryos have been successfully cryopreserved in many animal species. The sensitivity of embryos to cooling and freezing varies between species and stages of embryo development. We report here the cryopreservation procedures that allow a high survival rate of four- and eight-cell human embryos and the establishment of a pregnancy following the freezing and storage of an eight-cell embryo for 4 months in liquid nitrogen. The pregnancy terminated at 24 weeks' gestation due to development of a septic Streptomyces agalactiae chorion amnionitis after premature membrane rupture.     

Mammalian neural crest cells participate in normal embryonic development on microinjection into post-implantation mouse embryos

The production of chimaeric mice by aggregating pre-implantation mouse embryos or by injection of cells into the blastocyst has been of great value in analysing the regulation of early mammalian development and in dissecting the relationships of early cell lineages. While the totipotent cells of the pre-implantation embryo can be grown in vitro and thus are readily accessible to experimental manipulation, this is not possible after the embryo has implanted into the uterus. This problem has severely hampered the analysis of cell migration and of cell lineage relationships in later stages of mammalian development. In contrast, the chicken embryo can be manipulated experimentally throughout embryo-genesis and this has made the bird a favourable system for studying patterns of cell migration in the development of higher vertebrates. In mammals, the introduction of retroviruses and haematopoietic cells has provided two means of probing post-implantation development by direct intervention. I report here that cultured neural crest cells, when microinjected into 9-day-old mouse embryos, can migrate over considerable distances and participate in normal development, and the resulting chimaeric animals show pigmentation derived from the donor cells in hair and iris. The introduction of cells into post-implantation embryos may provide the means of studying patterns of cell migration in mammalian development at a level of sophistication which so far has been restricted to the chicken system.     

Inability of Rous sarcoma virus to cause sarcomas in the avian embryo

The injection of Rous sarcoma virus (RSV) into the wing web of newly hatched chicks causes a rapidly growing sarcomatous tumour which is palpable within 1 week of inoculation; and cultures of fibroblasts derived from chick embryos (CEF) and infected with RSV become rapidly transformed. Genetic studies have determined that expression of a single viral gene, designated v-src, is necessary for neoplastic transformation. This gene codes for a 60,000-molecular weight phosphoprotein termed pp60SPC , which possesses a protein kinase activity that phosphorylates polypeptides on tyrosine residues and is constitutively expressed in infected CEF cells. It has been suggested that transformation, and possibly tumorigenesis, may result solely from the consequences of this increase in tyrosine phosphorylations. The pathogenicity of RSV in chick embryos in ovo is less clear. Murphy and Rous suggested that RSV may have caused tumours in "various tissues" of "some embryos", but the subsequent studies of Milford and Duran - Reynals , as well as several other laboratories, failed to find any evidence of intraembryonic tumours in RSV-infected early embryos. The findings of Duran - Reynals , if correct, cannot be explained easily in view of our present understanding of RSV tumorigenicity. Thus, we have re-examined the interaction of RSV with the avian embryo and confirm here that RSV is nontumorigenic and non-teratogenic when microinjected into day 4 chicken embryos. In addition, we found that (1) the virus not only replicates in the embryo, but it also expresses an active src-specific protein kinase and (2) once the cells from the infected limbs are disrupted and placed in culture, they are capable of expressing the transformed phenotype after a 24-h delay.     

Earliest date for milk use in the Near East and southeastern Europe linked to cattle herding

The domestication of cattle, sheep and goats had already taken place in the Near East by the eighth millennium bc. Although there would have been considerable economic and nutritional gains from using these animals for their milk and other products from living animals-that is, traction and wool-the first clear evidence for these appears much later, from the late fifth and fourth millennia bc. Hence, the timing and region in which milking was first practised remain unknown. Organic residues preserved in archaeological pottery have provided direct evidence for the use of milk in the fourth millennium in Britain, and in the sixth millennium in eastern Europe, based on the delta(13)C values of the major fatty acids of milk fat. Here we apply this approach to more than 2,200 pottery vessels from sites in the Near East and southeastern Europe dating from the fifth to the seventh millennia bc. We show that milk was in use by the seventh millennium; this is the earliest direct evidence to date. Milking was particularly important in northwestern Anatolia, pointing to regional differences linked with conditions more favourable to cattle compared to other regions, where sheep and goats were relatively common and milk use less important. The latter is supported by correlations between the fat type and animal bone evidence.     

植物胚拯救技术的影响因素及其应用

胚拯救技术在拯救败育胚、阻止胚早期退化和培育新三倍体及多倍体等种质资源方面具有重要作用。植物胚拯救方法主要有3种:胚的活体转移、胚的活体培养及胚的离体培养。在植物胚的离体培养过程中,依据需拯救的植物胚胎发育程度,建立了离体子房培养、胚珠培养和幼胚培养3种培养方式。大量研究结果表明,胚龄、培养基种类及相态、培养条件、渗透压、生长调节剂、外源添加剂和基因型等均会影响植物胚拯救的成败,因而胚拯救技术作为传统育种方法的辅助手段,在突破拯救的胚龄极限、提高植株再生率等方面还有进一步发展的空间。此外,结合胚拯救技术和分子生物学的研究手段,有望通过遗传转化稳定不同特性的新种质,创新植物种质资源。     

Palaeontology: pterosaur embryo from the Early Cretaceous

Dinosaur embryos have been discovered all over the world, but so far no pterosaur embryos have been reported. Here we describe a Chinese fossil from the Early Cretaceous period containing an embryo that is unambiguously a pterosaur. The embryonic skeleton, which is exquisitely preserved in its egg, is associated with eggshell fragments, wing membranes and skin imprints. This discovery confirms that pterosaurs were egg-layers and sheds new light on our understanding of pterosaur development.     

波尔山羊的胚胎移植技术及应用

利用发情控制技术，将超过正常数量波尔山羊的胚胎移植到普通白山羊的体内，妊娠、产仔，获得更多波尔山羊的后代，借此扩大波尔山羊的种群。     

川西北高原地区羊皮资源的开发研究

对川西北高原地区羊皮资源、品质、加工鞣制、成品毛皮(革)品质、经济效益等进行了系统研究.结果表明,地该地区羊皮资源丰富,原料毛皮品质优良,用铬—铝结合加工鞣制后,成品毛皮(革)感观性优良,各项物理指标均达到或超过国家标准,加工试制为制品经济效益显著,具有开发价值,可进行计划开发利用.     

实验小鼠胚胎冷冻技术实验研究

本文在建立和引进实验小鼠超排卵技术、卵采集技术、胚胎输卵管移植技术的基础上 ,应用小鼠初期胚的快速冷冻复苏法对实验小鼠C5 7BL 6J、BDF1 、A wy及昆明种小鼠进行了初期胚的冷冻保存与仔鼠存活率的研究 ,并将冷冻复苏胚与非冷冻胚经移植后的生存率作了比较 ,均取得了重复性的结果 ,可望为实验小鼠胚胎种子库提供参考依据。     

Nuclear transplantation in sheep embryos

Nuclear transplantation and cell fusion techniques have proved valuable for embryological studies in several non-mammalian animal species. More recently these procedures have been used successfully in small laboratory mammals, notably the mouse, to investigate the ability of nuclei and cytoplasm from various sources to produce viable embryos when combined. The use of a similar approach to study the developmental biology of large domestic animals presents a number of technical and practical difficulties, and so far there has been no report of attempts to perform nuclear transplantation in sheep embryos. Here I describe such a procedure and its use to investigate the development of embryos in which whole blastomeres from 8- and 16-cell embryos were combined with enucleated or nucleated halves of unfertilized eggs. The procedure involves bisection of single-cell eggs in a medium containing cytochalasin; fusion of egg halves with single blastomeres, induced using Sendai virus or an electrofusion apparatus; and embedding in agar, followed by culture of the reconstituted embryos in the ligated oviducts of ewes in dioestrus. I show that fully viable embryos may be obtained by this procedure.     

大黄鱼与黄姑鱼杂交F_1及其双亲的核型分析

研究了大黄鱼与黄姑鱼正反交F1原肠早期胚胎细胞及其亲本头肾细胞的染色体核型,为深入剖析大黄鱼与黄姑鱼杂交后代的基因组构成提供了细胞遗传学证据.大黄鱼与黄姑鱼染色体组均含有48条端部着丝粒染色体,染色体组型公式均为2n=48 t,染色体臂数均为NF=48,组内染色体长度分布连续.两亲本物种间核型很相似,未找到鉴别两物种的细胞遗传标志.正反交F1原肠期胚胎细胞的染色体众数也均为48,均可较好地配为24对.结合前期AFLP分析结果可以推断,正反交胚胎细胞均同时含有一个大黄鱼染色体组和一个黄姑鱼染色体组.此外,杂交F1中的非整倍体比例与两亲本没有明显区别,初步表明杂交胚胎细胞未发生明显的染色体丢失.在黄姑鱼♀与大黄鱼♂杂交F1中出现4对非t-染色体,原因尚待查明.     

Discovery of phosphatized gastrula fossils from the Doushantuo Formation, Weng’an, Guizhou Province, China

Globular fossils from Doushantuo phosphorites at the Weng’an area are for the first time identified as a gastrulation stage of phosphatized embryos. They are got from the fossiliferous remains after acetic acid maceration. The fossils are found together with formerly reported animal resting eggs and embryos of the earlier cleavage stage. The oblate-shaped fossils with the same size as those reported embryos and invaginate at the middle part into the embryos, show the characteristics of the late blastula to the early gastrula stage of the embryo development. This discovery convinces the existence of animal embryos at Doushantuo age and offers new facts for the studying of the affinity of related fossils, which are still controversial at present.     

Hf-W-Th evidence for rapid growth of Mars and its status as a planetary embryo

Terrestrial planets are thought to have formed through collisions between large planetary embryos of diameter ～1,000-5,000?km. For Earth, the last of these collisions involved an impact by a Mars-size embryo that formed the Moon 50-150?million years (Myr) after the birth of the Solar System. Although model simulations of the growth of terrestrial planets can reproduce the mass and dynamical parameters of the Earth and Venus, they fall short of explaining the small size of Mars. One possibility is that Mars was a planetary embryo that escaped collision and merging with other embryos. To assess this idea, it is crucial to know Mars' accretion timescale, which can be investigated using the (182)Hf-(182)W decay system in shergottite-nakhlite-chassignite meteorites. Nevertheless, this timescale remains poorly constrained owing to a large uncertainty associated with the Hf/W ratio of the Martian mantle and as a result, contradicting timescales have been reported that range between 0 and 15?Myr (refs 6-10). Here we show that Mars accreted very rapidly and reached about half of its present size in only 1.8(+0.9)(-1.0) Myr or less, which is consistent with a stranded planetary embryo origin. We have found a well-defined correlation between the Th/Hf and (176)Hf/(177)Hf ratios in chondrites that reflects remobilization of Lu and Th during parent-body processes. Using this relationship, we estimate the Hf/W ratio in Mars' mantle to be 3.51?±?0.45. This value is much more precise than previous estimates, which ranged between 2.6 and 5.0 (ref. 6), and lifts the large uncertainty that plagued previous estimates of the age of Mars. Our results also demonstrate that Mars grew before dissipation of the nebular gas when ～100-km planetesimals, such as the parent bodies of chondrites, were still being formed. Mars' accretion occurred early enough to allow establishment of a magma ocean powered by decay of (26)Al.