排序方式: 共有78条查询结果,搜索用时 15 毫秒
61.
RNA synthesis in male pronuclei of the sea urchin 总被引:1,自引:0,他引:1
62.
63.
Piglets born from handmade cloning, an innovative cloning method without micromanipulation 总被引:5,自引:0,他引:5
Du Y Kragh PM Zhang Y Li J Schmidt M Bøgh IB Zhang X Purup S Jørgensen AL Pedersen AM Villemoes K Yang H Bolund L Vajta G 《Theriogenology》2007,68(8):1104-1110
Porcine handmade cloning (HMC), a simplified alternative of micromanipulation based traditional cloning (TC) has been developed in multiple phases during the past years, but the final evidence of its biological value, births of piglets was missing. Here we report the first births of healthy piglets after transfer of blastocysts produced by HMC. As a cumulative effect of technical optimization, 64.3+/-2.3 (mean+/-S.E.M.) reconstructed embryos from 151.3+/-4.8 oocytes could be obtained after 3-4h manual work, including 1h pause between fusion and activation. About half (50.1+/-2.8%, n=16) of HMC reconstructed embryos developed to blastocysts with an average cell number of 77+/-3 (n=26) after 7 days in vitro culture (IVC). According to our knowledge, this is the highest in vitro developmental rate after porcine somatic cell nuclear transfer (SCNT). A total of 416 blastocysts from HMC, mixed with 150 blastocysts from TC using a cell line from a different breed were transferred surgically to nine synchronized recipients. Out of the four pregnancies (44.4%) two were lost, while two pregnancies went to term and litters of 3 and 10 piglets were delivered by Caesarean section, with live birth/transferred embryo efficiency of 17.2% (10/58) for HMC. Although more in vivo experiments are still needed to further stabilize the system, our data proves that porcine HMC may result in birth of healthy offspring. Future comparative examinations are required to prove the value of the new technique for large-scale application. 相似文献
64.
Du Y Li J Kragh PM Zhang Y Schmidt M Bøgh IB Zhang X Purup S Kuwayama M Jørgensen AL Pedersen AM Villemoes K Yang H Bolund L Vajta G 《Cloning and stem cells》2007,9(4):469-476
Successful cryopreservation of porcine embryos offers a promising perspective in the fields of agriculture, animal science, and human medical research. The objective of the present work was to establish a system facilitating the cryopreservation of porcine embryos produced by somatic cell nuclear transfer (SCNT). Several key techniques including micromanipulator-based enucleation, noninvasive delipation, zona-free fusion, and activation were combined with high efficiency. After a partial zona digestion and high-speed centrifugation, 89.8+/-2.1% (mean+/-SEM) of enucleated oocytes were successfully delipated. Delipated cytoplasts were incubated for an additional 0.5 or 2 h before fusion with somatic cells. After activation and 6 days of in vitro culture, no significant difference in the rate of blastocysts per reconstructed embryo was observed between the two groups (33.1+/-1.8% and 26.0+/-4.3% for 0.5 and 2 h recovery time, respectively). Cryopreservation of the blastocysts was performed with a Cryotop device and factory-prepared vitrification and warming solutions. One hundred fifty-five vitrified SCNT embryos were transferred surgically into two recipient sows to test their developmental capacity in vivo. One recipient became pregnant and delivered six piglets. In conclusion, our simplified delipation and SCNT procedure resulted in viable piglets after vitrification and embryo transfer at the blastocyst stage. 相似文献
65.
Sren Kragh Moestrup Erik Ils Christensen Lars Sottrup-Jensen Jrgen Gliemann 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1987,930(3)
125I-labelled pregnancy zone protein complex was injected intravenously in rats and after 6 min uptake into cells of the liver and spleen was determined by electron microscopic autoradiography. The liver took up 68% of the injected radioactivity; 61% was in the hepatocytes and 7% was in the liver macrophages (Kupffer cells). The spleen took up 3–4% and nearly all the radioactivity was in the macrophages of the red pulp. The uptake per cell volume was several times higher in the macrophage than in the hepatocyte. The radioactivity associated with macrophages was largely in endocytotic vacuoles and lysosomes. Binding of labelled pregnancy zone protein complex to peritoneal macrophages at 4°C was 2–3-times higher than binding of the homologous α2-macroglobulin complex. The two ligands competed for binding to the same receptors and the difference was due to a higher affinity of the pregnancy zone protein complex (Kd approx. 60 pM). After binding to the receptor, this ligand was internalised within 2–3 min at 37°C and radioactivity inside the cells largely represented intact pregnancy zone protein complex. Radioactivity was released from the cell as iodotyrosine after a lag time of about 10 min. It is concluded that pregnancy zone protein complex is bound with a high affinity to the α2-macroglobulin receptors in rat macrophages followed by receptor-mediated endocytosis and degradation of the ligand in the lysosomes. 相似文献
66.
Silencer region of a chalcone synthase promoter contains multiple binding sites for a factor,SBF-1, closely related to GT-1 总被引:14,自引:0,他引:14
67.
Damjan Manevski Nina Ružić Gorenjec Per Kragh Andersen Maja Pohar Perme 《Biometrical journal. Biometrische Zeitschrift》2023,65(4):2200070
For cohorts with long-term follow-up, the number of years lost due to a certain disease yields a measure with a simple and appealing interpretation. Recently, an overview of the methodology used for this goal has been published, and two measures have been proposed. In this work, we consider a third option that may be useful in settings in which the other two are inappropriate. In all three measures, the survival of the given dataset is compared to the expected survival in the general population which is calculated using external mortality tables. We thoroughly analyze the differences between the three measures, their assumptions, interpretation, and the corresponding estimators. The first measure is defined in a competing risk setting and assumes an excess hazard compared to the population, while the other two measures also allow estimation for groups that live better than the general population. In this case, the observed survival of the patients is compared to that in the population. The starting point of this comparison depends on whether the entry into the study is a hazard changing event (e.g., disease diagnosis or the age at which the inclusion criteria were met). Focusing on the newly defined life years difference measure, we study the estimation of the variance and consider the possible challenges (e.g., extrapolation) that occur in practice. We illustrate its use with a dataset of French Olympic athletes. Finally, an efficient R implementation has been developed for all three measures which make this work easily available to subsequent users. 相似文献
68.
Swapnil Chouhan Kanchan Chauhan Sunita Kataria Guruprasad KN 《Journal of Plant Biology》2008,51(2):132-138
The impact of exclusion of solar UV-B (280–320 nm) and UV-A+B (280–400 nm) radiation on the root nodules was studied in soybean(Glycine max var. MACS 330). Soybean plants were grown in the tropical region of Indore (Latitude-22.4°N), India under field conditions
in metal cages covered with polyester exclusion filters that specifically cut off UV-B (<320 nm) and UV-A+B (<400 nm) radiation;
control plants were grown under ambient solar radiation. Leghemoglobin content was analyzed in the root nodules on the 50th day after emergence of seedlings. Exclusion of UV radiations significantly enhanced the leghemoglobin content in the nodules
on fresh weight basis; 25% and 45% higher amount of leghemoglobin were present in the nodules after the exclusion of UV-B
and UV-A+B radiation respectively. Analysis by native and SDS-PAGE showed high intense bands of leghemoglobin after the exclusion
of UV-A+B as compared to control. Exclusion of UV radiation also enhanced the growth of roots as well as aerial parts of the
plants. UV Exclusion increased nodulation by increase in the number and size of nodules. The results are discussed in the
light of advantage of exclusion for enhancing protein/nitrogen content in the plants. 相似文献
69.
Efficient in vitro production of porcine blastocysts by handmade cloning with a combined electrical and chemical activation 总被引:3,自引:0,他引:3
The purpose of our work was to establish an efficient protocol for activation of porcine cytoplast-fibroblast constructs produced by the handmade cloning technique. Firstly, we investigated a combined electrical and chemical activation protocol for parthenogenetic development of in vitro matured zona-free oocytes. Oocytes were activated by one 80 micros pulse and subsequently cultured in cytochalasin B and cycloheximide. Developmental rates of blastocysts from activated oocytes were 49+/-1 and 40+/-2%, when using one 80 micros pulse of 0.85 or 1.25 kV/cm, respectively. The activation procedure was further confirmed by a simultaneous re-fusion and activation of bisected oocytes, resulting in a blastocyst rate of 41+/-8%. Secondly, the activation protocol was applied in the handmade cloning technique. In vitro matured zona-free porcine oocytes were bisected and halves containing no chromatin, i.e. the cytoplasts, were selected. Reconstructed embryos were produced by a two-step fusion procedure. At the first step, one cytoplast was fused to one fibroblast by one 80 micros pulse of 1.25 kV/cm. After 1h, the cytoplast-fibroblast pair and another cytoplast were fused and activated simultaneously by one 80 micros pulse of 0.85 kV/cm, and subsequently cultured in cytochalasin B and cycloheximide. The development of reconstructed embryos to the blastocyst stage was in average 21+/-4%, and total blastocyst cell counts were in average 48+/-3. Thus, the combined electrical and chemical activation procedure resulted in efficient blastocyst development in the handmade cloning technique. 相似文献
70.
Sørensen JF Kragh KM Sibbesen O Delcour J Goesaert H Svensson B Tahir TA Brufau J Perez-Vendrell AM Bellincampi D D'Ovidio R Camardella L Giovane A Bonnin E Juge N 《Biochimica et biophysica acta》2004,1696(2):275-287
The nutrient content of food and animal feed may be improved through new knowledge about enzymatic changes in complex carbohydrates. Enzymatic hydrolysis of complex carbohydrates containing alpha or beta glycosidic bonds is very important in nutrition and in several technological processes. These enzymes are called glycosidases (Enzyme Class 3.2.1) and include amylases, pectinases and xylanases. They are present in many foods such as cereals, but their microbial analogues are often produced and added in many food processes, for instance to improve the shelf-life of bakery products, clear beer, produce glucose, fructose or dextrins, hydrolyse lactose, modify food pectins, or improve processes. However, many plant foods also contain endogenous inhibitors, which reduce the activity of glycosidases, in particular, proteins, peptides, complexing agents and phenolic compounds. The plant proteinaceous inhibitors of glycosidases are in focus in this review whose objective is to report the effect and implications of these inhibitors in industrial processes and applications. These studies will contribute to the optimisation of industrial processes by using modified enzymes not influenced by the natural inhibitors. They will also allow careful selection of raw material and reaction conditions, and future development of new genetic varieties low in inhibitors. These are all new and very promising concepts for the food and feed sector. 相似文献