转基因动物技术应用研究进展

自Pal miter等〔1〕(1982)把大鼠生长激素基因导入小鼠受精卵获得超级巨鼠以来,世界各国科学家对转基因技术应用于动物生产的研究产生了极大的兴趣,并相继在兔、羊、猪、牛、鸡、鱼等动物上获得转基因成功。转基因动物研究是近年来生命科学中最热门、发展最快的领域之一,其应用已广泛渗透于分子生物学、发育生物学、免疫学、制药及畜牧育种等各个研究领域中。这项技术正在对动物生产产生一场新的革命,在提高生长速度、生产性能,改善产品品质、抗病育种、基因治疗等方面取得了可喜的进展,显示出诱人的应用前景。1转基因动物技术转基因技术就…     

转基因羊研究进展

转基因动物研究始于上世纪70年代,至今已在牛、羊、猪、鱼、猴、兔、狗和猫等动物身上取得转基因成功.根据目前的生命科学和生物技术的发展现状和趋势,动物转基因技术和动物克隆技术的有机结合既有迫切性又有必然性.转基因克隆动物技术在畜牧业上的应用前景也相当诱人,转基因克隆动物的研究将成为今后国际范围内生物工程领域的竞争热点.文中综述了国内外利用转基因技术培育绵羊和山羊新品种,进行羊乳腺生物反应器和生产生物材料的研究以及我国目前正在进行的转基因羊项目,在论述转基因动物发展有利方面的同时,指出了转基因羊存在的问题和今后的研究方向及发展前景.     

转基因技术在畜牧生产中的应用

80年代早期 ,产生了将外源基因显微注射到受精卵 ,产生携带外源基因的动物品系新技术 ,这种携带有外源基因的动物称为“转基因动物”。随着现代分子生物学技术的发展 ,相继出现了 DNA体外重组、某些重要生产性状基因的分离、基因融合、胚胎体外操作等转基因相关技术 ,并在畜牧生产中得到了广泛的应用。目前已报道的转基因动物有线虫、果蝇、海胆、两栖动物、鱼类、小鼠、猪、牛、羊、鸡、兔等。本文就目前转基因的方法及该技术在提高畜禽生产性能、抗病育种、疾病治疗等方面的应用作一论述。1　外源基因转移方法1 .1　显微注射法　 Jaenis…     

转基因技术在奶牛育种中的应用

转基因动物在现代生物技术领域中极其重要,目前已有转基因鼠、兔、猪、牛、鱼、鸡等多种转基因动物相继问世。文章论述了转基因技术的原理、技术方法以及转基因技术在奶牛育种中的应用,同时也指出了转基因动物存在的不足,展望了其发展前景。     

兔转基因成纤维细胞克隆的建立及条件优化

探索和优化兔成纤维细胞由单细胞成长为克隆群体的技术条件,建立转基因单克隆细胞系筛选系统,为进一步生产基因打靶克隆兔创造条件。将3～5代的成纤维细胞分散成单个细胞,对比不同培养基对单细胞克隆形成的影响。利用脂质体转染兔成纤维细胞后,按照不同的稀释比例传代并筛选转基因单细胞克隆,研究不同稀释比例对转基因单细胞克隆形成的影响。经过比较试验发现同化的DMEM/F12培养基能很好地支持单细胞克隆早期生长,转基因后1∶80倍的稀释比例能够获得较多的转基因单细胞克隆。本试验结果有助于提高转基因和基因打靶克隆动物的制作效率。     

用注射器直接对睾丸打点注射EGFP生产转基因兔的试验研究

为探讨直接用 1 mL 注射器对睾丸打点注射pIRES2-EGFP建立操作方便、效率高、成本低、可批量生产转基因兔的可行性.选择4只成年新西兰雄兔,双侧睾丸内分别打点注射 0.5～0.8 mg/mL浓度的质粒 0.25 mL,第 3 周和第 8 周分别取4#和3#雄兔睾丸做冰冻切片,置荧光显微镜下观察是否发绿色荧光.其它雄兔于第 3 周开始参与配种,最后采新生仔兔耳组织提取其基因组进行 PCR 和 Southern 杂交检测阳性率.结果表明,雄兔睾丸冰冻切片于荧光显微镜下可见绿色荧光,PCR 和 Southern 杂交检测表明在睾丸注射后的第 6 周和第 7 周进行配种所得后代阳性率最高.不同雄兔后代经 PCR 和 Southern 杂交检测平均阳性率存在差异(P<0.05),2#雄兔后代平均阳性率达到 56.46%,3#雄兔的最低达36.96%的阳性率.表明用注射器直接对睾丸打点注射外源基因生产转基因的方法操作简便、高效,为大规模制备一些大型家畜的转基因后代奠定了基础.     

转基因动物在畜牧业上的应用

转基因动物是当代应用生物工程技术。将外源基因导入动物受精卵中，使其稳定整合到动物染色体上，能将遗传性状表达而传递给后代，形成转基因鼠，转基因兔，转基因猪，转基因羊，转基因鱼等多种转基因畜禽。该技术对改良畜禽，提高生产性能，抗病力和节粮型畜牧业发展具有巨大潜力。     

转基因植物可食疫苗研究进展

利用转基因植物生产疫苗是一种经济、方便的方法。目前已有一些细菌和病毒等病原抗原编码基因在植物中成功地得到了表达 ,并且保留了自身的免疫特性 ,通过口服或非经肠道免疫能刺激免疫反应 ,甚至有保护作用。文章就变异链球菌表面蛋白、大肠杆菌热敏肠毒素 B亚单位、霍乱毒素 B亚单位、乙肝病毒表面抗原、Norwalk病毒衣壳蛋白、狂犬病病毒糖蛋白、传染性胃肠炎糖蛋白 S、口蹄疫病毒 VP1、兔出血病病毒等在转基因植物中的表达及其免疫原性研究作了综述。表明利用转基因植物生产可食疫苗是可行的 ,然而还存在一些问题 ,有待于进一步研究     

转基因动物研究进展

转基因动物是现代生物技术中一个极其重要的研究领域，目前已经有转基因小鼠、兔、绵羊、山羊、猪、牛、鸡和鱼等多种转基因动物问世。本文综述了转基因动物的制作方法、转基因动物的应用研究以及所取得的重要成就，并指出了转基因动物存在的主要问题，展望了其发展前景。     

转基因大动物常用载体频数分析及筛查策略

构建重组表达载体是转基因动物生产制备研究中非常关键的一步,包括构建完整的外源基因表达盒,包含目的基因、调控序列(启动子、终止子)和筛选报告基因等。本文概述了转基因大动物制备技术,归纳统计了近10年转基因猪、牛、羊制备过程中常用的载体和频数,统计结果表明,转基因猪中启动子频数从多到少依次为酪蛋白、CAG、CMV启动子,终止子频数依次为兔β-globin poly A、酪蛋白poly A、SV40poly A和BGH poly A;转基因羊中启动子频数从多到少依次为酪蛋白、BLG和CMV启动子,终止子依次为酪蛋白poly A、BLG poly A、BGH poly A、SV40poly A和兔β-globin poly A;转基因牛中启动子频数从多到少依次为酪蛋白、CMV、人乳清白蛋白启动子等,终止子依次为SV40poly A、BGH poly A和酪蛋白poly A。根据统计结果提出针对启动子和终止子的多重检测和筛查策略;分析了未来转基因动物检测可能存在的问题,以期对转基因动物的监管和筛查检测方法的建立提供参考。     

Ultrastructural morphometry of mammary gland in transgenic and non-transgenic rabbits

The mammary gland of transgenic animals has been used for the production of recombinant proteins of therapeutic and nutraceutical use. The objective of this study was to compare the ultrastructure of transgenic and non-transgenic rabbit mammary gland tissue. New Zealand White transgenic rabbits were obtained by breeding non-transgenic rabbits with transgenic founder rabbits containing a whey acidic protein-human factor VIII (WAP-hFVIII) transgene integrated into their genome. Samples of mammary gland tissue from lactating rabbit females were isolated by surgical procedures. These samples were examined by optical and electron microscopy and photographs were taken. Measurements of ultrastructural organelles were made from digital images of the mammary cells. No differences were found in the cellular structure of mammary tissue, but significant differences t((0.001)) in the relative volume of mitochondria and vacuoles between transgenic and non-transgenic mammary gland epithelium were observed.     

First Report on the Occurrence of ‘Helicobacter heilmannii’ in the Stomach of Rabbits

Gastric Helicobacter spp. have been described in a wide range of animal species, including dogs, cats, primates, swine, cattle and rodents. However, in lagomorphs--more specifically rabbits--gastric Helicobacter infections have never been reported. Biopsy specimens were collected from different stomach regions of 23 rabbits, including 10 pet rabbits, 10 industrial animals and 3 research animals. These were subjected to a PCR assay for the detection of Helicobacter DNA. Identification up to the species level was based on 16S rRNA sequence analysis and a recently developed multiplex PCR. Seven rabbits (four pet, one research animal and two industrial animals) tested positive in the Helicobacter genus-specific PCR in the stomach, with the corpus being predominantly positive. H. felis and H. salomonis, hitherto presumed to be naturally hosted by cats and dogs, were detected in three animals and one animal, respectively. One of these animals had been completely devoid of any form of contact with cats or dogs. A H. pullorum/H. rappini-like organism (96% 16S rDNA sequence similarity) was found in an industrially held rabbit. The helicobacters of the two remaining rabbits could not be identified up to the species level. To conclude, this is the first report on the occurrence of Helicobacter spp. in the stomach of rabbits. In view of the fact that H. felis and H. salomonis are put forward as having zoonotic potential, further research is necessary to investigate the implications of these findings not only for the rabbit but also for human health.     

Assessing the fate of recombinant plant DNA in rabbit’s tissues fed genetically modified cotton

Various feeding studies have been conducted with the different species of animals to evaluate the possible transfer of transgenic DNA (tDNA) from genetically modified (GM) feed into the animal tissues. However, the conclusions drawn from most of such studies are sometimes controversial. Thus, in the present study, an attempt has been made to evaluate the fate of tDNA in rabbits raised on GM cotton-based diet through PCR analysis of the DNA extracted specifically from blood, liver, kidney, heart and intestine (jejunum). A total of 48 rabbits were fed a mixed diet consisting variable proportions of transgenic cottonseeds meal (i.e. 0% w/w, 20% w/w, 30% w/w and 40% w/w) for 180 days. The presence of transgenic DNA fragments (Cry1Ac, Cry2A and CP4 EPSPS) or plant endogenous gene (Sad1) was traced in those specific tissues and organs. The presence of β-actin (ACTB) was also monitored as an internal control. Neither the transgenic fragments (459 bp of Cry1Ac gene, 167 bp of Cry2A gene and111 bp of CP4 EPSPS gene) nor cotton endogenous reference gene (155 bp of Sad1) could be detected in any of the DNA samples extracted from the rabbit's tissues in both control and transgenic groups. However, 155 bp fragment of the rabbit's reference gene (ACTB) was recovered in all the DNA samples extracted from rabbit tissues. The results obtained from this study revealed that both plant endogenous and transgenic DNA fragments have same fate in rabbit's tissues and were efficiently degraded in the gastrointestinal tract (GIT).     

Genetic engineering of mammalian embryos

A gene consisting of the mouse metallothionein I promoter/regulator (MT) fused to the human growth hormone (hGH) structural gene (MThGH) was microinjected into rabbit, sheep and pig eggs. Visualization of nuclear structures was accomplished by interference-contrast (I-C) microscopy for rabbit and sheep eggs and by centrifugation and I-C microscopy for pig eggs. The gene integrated into the chromosomes of each species with an efficiency of 13% in rabbits, 1% in sheep and 10% in pigs. Human GH mRNA was detected in the liver of transgenic rabbits as well as tail and ear samples of pigs. Immunoreactive hGH was present in the serum of a transgenic rabbit and plasma of most transgenic pigs. In several pigs hGH levels increased between birth and 90 d of age. The presence of substantial quantities of hGH in plasma of pigs did not increase postnatal somatic growth rates. Founder animals will be bred and their transgenic and control progeny used to assess the effects of hGH on feed efficiency and carcass composition. These experiments demonstrate the feasibility of introducing foreign genes into the genome of several animal species by microinjection of eggs.     

Gene transfer in laboratory animals

Describing purpose and method of genetransfer by pronuclear microinjection comprehensively application on laboratory animals are reviewed. Experiments on the production of rabbits and mice transgenic for several uteroglobin-hybrid-genes (B2B3UG CAT; H/B/72/CAT; UG TAg; UG 11.8) were performed and resulted in four rabbit fetuses and one stillborne rabbit transgenic for UG TAg and one mouse transgenic for UG 11.8. These experiments are part of investigations on uteroglobin as a model of geneexpression regulated by steroid hormones.     

Encephalitozoonosis in New Zealand rabbits and potential transmission risk

Encephalitozoon cuniculi is a small protozoan parasite in the phylum Microspora. It has been shown to naturally infect several host species, including humans. Encephalitozoonosis is routinely diagnosed in vivo by serological examination or post mortem by histopathology. In a conventional rabbit colony, two animals suddenly showed clinical signs (torticollis and asthenia of limbs). Serum samples of these rabbits were seropositive for E. cuniculi after definitive diagnosis (Toxoplasma gondii and Listeria monocytogenes). The animals in the same breeding facility were also clinical examined, and the present study evaluated the prevalence of specific anti-E. cuniculi antibodies using serological testing, both in animals and in people working with animals, after two clinical cases. The rabbits showed no clinical symptoms of the disease. Blood samples were taken for E. cuniculi infection from 50 clinically healthy rabbits. Anti-E. cuniculi antibodies were found in two asymptomatic and two clinically affected animals belonging to the same rabbit colony. Finally, the present study found that the 7.7% (4/52) prevalence of CIA, test positive in rabbits. E. cuniculi spores were detected in the urine of one clinically affected rabbit, and one seropositive animal caretaker after staining with the modified trichrome stain. In conclusion, the presence of seropositive, but apparently healthy rabbits indicates the need for screening examinations to detect the anti-E. cuniculi antibody in rabbits, especially considering the potential zoonotic risk. Therefore, persons should avoid contact with the urine of infected or healthy animals, and always use good personal hygiene when handling animals.     

Transgenic mouse offspring generated by ROSI

The production of transgenic animals is an important tool for experimental and applied biology. Over the years, many approaches for the production of transgenic animals have been tried, including pronuclear microinjection, sperm-mediated gene transfer, transfection of male germ cells, somatic cell nuclear transfer and the use of lentiviral vectors. In the present study, we developed a new transgene delivery approach, and we report for the first time the production of transgenic animals by co-injection of DNA and round spermatid nuclei into non-fertilized mouse oocytes (ROSI). The transgene used was a construct containing the human CMV immediate early promoter and the enhanced GFP gene. With this procedure, 12% of the live offspring we obtained carried the transgene. This efficiency of transgenic production by ROSI was similar to the efficiency by pronuclear injection or intracytoplasmic injection of male gamete nuclei (ICSI). However, ICSI required fewer embryos to produce the same number of transgenic animals. The expression of Egfp mRNA and fluorescence of EGFP were found in the majority of the organs examined in 4 transgenic lines generated by ROSI. Tissue morphology and transgene expression were not distinguishable between transgenic animals produced by ROSI or pronuclear injection. Furthermore, our results are of particular interest because they indicate that the transgene incorporation mediated by intracytoplasmic injection of male gamete nuclei is not an exclusive property of mature sperm cell nuclei with compact chromatin but it can be accomplished with immature sperm cell nuclei with decondensed chromatin as well. The present study also provides alternative procedures for transgene delivery into embryos or reconstituted oocytes.     

利用微卫星标记分析5个家兔品种内的遗传多样性

本研究利用微卫星标记分析了我国5个家兔品种内的遗传多样性。结果表明:在5个品种中,新西兰兔有效等位基因数最多,为6.545 5;加利福尼亚兔有效等位基因数最少,为3.000。比利时兔平均多态信息含量和平均杂合度最大,分别为0.570 4和0.823 3;加利福尼亚兔平均多态信息含量和平均杂合度最小,分别为0.499 7和0.589 7。     

Morphology of Testes from Transgenic Rabbits: Histological and Ultrastructural Aspects

The aim of this study was to compare morphological characteristics of testes from transgenic (the WAP-hFVIII gene) and non-transgenic rabbits with emphasis on the histological and ultrastructural aspects. Samples of testes from both groups were fixed and embedded into Durcupan ACM for transmission electron microscopy. For histological analysis, semi-thin toluidine blue-stained sections were evaluated under a Jenaval light microscope. Male fertility was tested based on egg fecundity and blastocyst yield; transgene transmission was proved using PCR assay. Spermatogenesis in rabbit testes had not been destroyed both in transgenic and non-transgenic rabbits. No significant differences were found in the occurrence of individual cell organelles of the Sertoli cells in transgenic and non-transgenic rabbits. The ultrastructure of Leydig cells in testes of transgenic and non-transgenic rabbits was rather similar. No differences in the occurrence of individual organelles of Leydig cells between transgenic and non-transgenic males were found. These results were in concert with fertilizing capacity of transgenic spermatozoa. The presented status of organelles in this study indicates functional activity of the analysed cells.     

Evaluation of haematological, biochemical and histopathological parameters of transgenic rabbits

The aim of our study was to compare the hFVIII mRNA expression in different organs, pathological changes and selected haematological and biochemical blood parameters between transgenic and non-transgenic rabbits from F3 generation. Selected physiological parameters of 3- to 4-month-old transgenic rabbits from F3 generation carrying human factor VIII gene (hFVIII) were analysed and compared with those of non-transgenic ones. Before slaughtering, the blood for haematological and biochemical analysis was taken from the central ear artery. Pathological and histological examination of vital organs and RT-PCR analysis of several tissue organs of transgenic and non-transgenic animals were performed after slaughtering. Except for the mammary gland tissue, slight hfVIII mRNA expression in the spleen, lung and brain and none expression in the liver, kidney, skeletal muscle and heart of rabbits were recorded. pathological examination of vital organs showed some pathological changes in both transgenic and non-transgenic rabbits which were confirmed by histological qualitative evaluations. Statistically significant lower values of blood haemoglobin in blood of transgenic (11.86+/-0.86) animals compared with non-transgenic (12.41+/-1.02, P<0.05) ones and lower parameters of HCT (39.22+/-2.44 versus 40.89+/-2.26, P<0.01) in blood of transgenic rabbits were observed. Parameters of WBC, RBC and PLT showed no significant differences between the analysed groups. All biochemical serum parameters of transgenic rabbits were higher in comparison with non-transgenic ones. Significant differences were found in the concentration of the urea, AST and GMT between transgenic and non-transgenic animals (P<0.001) and in the total protein content, the difference was significant at P<0.05. In conclusion, our results showed that no considerable impact on the general health was found in transgenic rabbits.