Loss of antibody production accompanied by chromosome loss in a cloned hybrid line secreting antibodies to sheep red blood cells

Summary Somatic cell hybrids between Sp2/O-Ag14 mouse myeloma cells and lymphocytes derived from BALB/c mice hyperimmunized with sheep red blood cells (SRBC) were produced. One hybrid producing IgG₁ antibody to SRBC was selected, cloned twice and subsequently transferred to BALB/c mice. After a number of transfers it was found that the antibody titer in ascitec fluid gradually decreased. Cytogenetic analysis revealed gradual chromosome loss in the hybrid clone, which produced progressively less antibody.     

生物工程与现代农业

介绍了世界农业面临的形势与任务，论述了生物工程技术在农业领域应用研究进展，并对我国未来农业发展进行了展望，提出了建议。     

克隆猴在中国率先突破,到底靠的是什么?

 中国科学家孙强研究团队利用类似克隆羊多莉的体细胞克隆技术，在国际上率先获得了克隆猴的成功，这一成果于2018年1月25日发表在《Cell》上。本文回顾了克隆猴的技术流程和难点、体细胞克隆动物简史及国内外克隆猴不成功的历史，点评了克隆猴成功的关键和意义，指出需要更多的实验室来推动该技术的优化。     

实验用小型猪胎儿成纤维细胞和骨髓间充质细胞为核供体生产转基因克隆胚胎

目的比较不同类型体细胞对生产转基因克隆胚胎效率的影响。方法利用脂质体介导的方法将质粒pEGFP-N1转染到五指山小型猪胎儿成纤维细胞和骨髓间充质细胞,经过G418筛选后均获得了阳性细胞株。然后分别以两种类型转基因细胞以及未转基因细胞为核供体进行体细胞核移植,比较不同类型供体细胞克隆胚胎的囊胚发育率。结果胎儿成纤维细胞和骨髓间充质细胞克隆胚的囊胚发育率差异不显著(P>0.05,8.3%vs.7.1%);转基因胎儿成纤维细胞(9.6%)和转基因骨髓间充质细胞(9.9%)克隆胚胎的囊胚发育率差异不显著(P>0.05,9.6%vs.9.9%);每一种类型供体细胞转基因与否对克隆胚的囊胚发育率无影响(P>0.05)。结论通过体细胞核移植技术,小型猪骨髓间充质细胞与胎儿成纤维细胞均可有效地生产转基因囊胚。     

Apoptosis of transgenic cloned and recloned bovine blastocysts

Apoptosis plays an important role in preimplantation embryonic development. Investigating mechanisms of apoptosis can provide useful information for obtaining high-quality embryos and help to improve cloning efficiency. Here, we investigated the incidence of blastomere apoptosis in transgenic blastocysts generated by somatic cell nuclear transfer (SCNT) and recloning using a terminal deoxynucleotidyl transferase-mediated d-UTP nick end-labeling (TUNEL) assay. Transgenic recloned embryos were the second generation SCNT embryos derived from the somatic cells of a transgenic SCNT calf. The blastocyst rate of transgenic SCNT embryos was lower than that of nontransgenic SCNT embryos. The incidence of apoptosis in transgenic SCNT embryos was higher than that of nontransgenic SCNT embryos. The blastocyst rate and the incidence of apoptosis in transgenic recloned embryos were similar to nontransgenic SCNT embryos. The process of donor cell transfection and drug selection may decrease the developmental capacity of transgenic SCNT embryos. Serial cloning did not influence the developmental capacity of transgenic recloned embryos.     

小鼠皮肤移植特异耐受性的获得

通过２个不同品系小鼠间进行皮肤移植，研究免疫系统产生特异耐受的机制。要获得对异体抗原的特异性耐受的机制。要获得对异体抗原的特异性耐受，必要包括对中淋巴器官中免疫效应细胞的特样伤，并同时诱导中枢免疫器官将其作为“自我”物质进行识别，导致系列克隆流产。     

平衡方法及平衡和解冻温度对牛体外受精胚胎玻璃化冷冻保存效果的研究

以体外成熟、体外受精并体外发育的牛囊胚为实验材料进行玻璃化冷冻保存，分别探讨了防冻剂的平衡方法以及平衡和解冻温度对胚胎冷冻效果的影响．实验结果显示，在室温下（１８℃）以二步法或三步法添加防冻剂的冷冻效果，明显优于在４℃下，以二步法添加防冻剂的效果，其冷冻—解冻胚的发育率分别为６２．８％（５９／９４）、５３．１％（５２／９８）和１４．６％（１２／８２）（Ｐ＜０．０１）；另外，室温下以二步法玻璃化冷冻的胚胎，在２０℃水浴中解冻的发育率明显高于３７℃解冻的效果，６２．７％（３７／６２）、２６．２％（１６／６１）（Ｐ＜０．０１）．结果表明：体外成熟、体外受精的牛胚胎可以进行玻璃化冷冻保存，并能得到较高的培养存活率，在室温下，以二步法添加防冻剂，并于２０℃下解冻的玻璃化冷冻保存方法是一种快速、简便而有效的方法．     

Seasonal influence on the development of parthenotes and cloned embryos in pigs

Seasonal influence on the developmental ability of porcine embryos was studied by comparisons of the number of cumulus-oocytes-complexes (COCs) per ovary pair and meiotic maturation ability of oocytes in different seasons; and by the observations on developmental competence of the parthenogenetic oocytes and cloned embryos collected from different seasons. We found that the number of COCs per ovary pairs was significantly higher in spring compared to the other seasons (P<0.05). However, no significant difference was found in the rate of oocytes progressing to MⅡ in four seasons (P<0.05). In addition, the rate of blastocyst formation of parthenogenetic embryos in summer was obviously declined compared to the other seasons (P<0.05), and an increased blastocyst rate of cloned porcine embryos was found in spring compared to autumn and winter (P<0.05). The results suggest that there should be a seasonal influence on the developmental competence of porcine embryos.     

yC16基因在Escherichia coli中的表达及表达产物的纯化

ｙＣ１６（ｃＤＮＡ,２．９ｋｂ）是果蝇ｙｅｍａ基因的转录片段,为制备ｙＣ１６编码蛋白免疫原,本实验用ＧＳＴ融合基因表达载体ｐＧＥＸ－２Ｔ在Ｅｓｃｈｅｒｉｃｈｉａｃｏｌｉ中合成该基因的蛋白,并与谷胱苷肽－ｓ－转移酶（ＧＳＴ）融合形成融合蛋白,结果由裂解细菌所得的融合蛋白为水溶性,并且可以在非变性的条件下,通过亲和层析作用在固定化的谷胱苷肽上加以纯化,然后再利用具有识别特异位点的蛋白水解酶－凝血酶或凝