尽管新一代基因编辑技术CRISPR/Cas9拥有众多优点,但在执行单个碱基水平的突变时其效率往往很低。由于DNA的双链断裂具有很多的不确定性,又加上基于供体模板的同源末端重组(homology directed repair,HDR)仅仅发生在分裂活跃的细胞中,...尽管新一代基因编辑技术CRISPR/Cas9拥有众多优点,但在执行单个碱基水平的突变时其效率往往很低。由于DNA的双链断裂具有很多的不确定性,又加上基于供体模板的同源末端重组(homology directed repair,HDR)仅仅发生在分裂活跃的细胞中,而非同源末端连接(non-homologous end joining,NHEJ)在整个细胞周期中都可以发生,因此,传统CRISPR/Cas9在单碱基分辨率上进行基因编辑时存在一定弊端。碱基编辑器(base editor,BE)的出现则在一定程度上弥补了这一缺陷。胞嘧啶碱基编辑器(cytosine base editor,CBE)或腺嘌呤碱基编辑器(adenine base editor,ABE)都能够在不引起双链断裂的情况下实现C·G到T·A或A·T到G·C的转换,极大地提高了单碱基编辑的应用价值。本文侧重对出现较早的CBE的原理、发展、应用及存在的问题进行综述,以期为高效单碱基突变工具在生物医学和畜牧业生产中的应用提供有益的参考和借鉴。展开更多
为了研究乳腺过表达褪黑素合成限速酶乙酰血清素甲基转移酶(ASMT,HIOMT)基因奶山羊的生物安全性,试验针对乳腺过表达褪黑素合成酶ASMT基因奶山羊模型,记录了转基因山羊的生长发育数据、检测了血液及尿液中生理生化指标,并对肠道微生物...为了研究乳腺过表达褪黑素合成限速酶乙酰血清素甲基转移酶(ASMT,HIOMT)基因奶山羊的生物安全性,试验针对乳腺过表达褪黑素合成酶ASMT基因奶山羊模型,记录了转基因山羊的生长发育数据、检测了血液及尿液中生理生化指标,并对肠道微生物、乳成分及褪黑素含量进行分析。结果表明:1)转基因阳性羊0,3,6,12月龄体重、体长、身高和胸围四项生长指标和对照羊均无显著差异(P>0.05);2)转基因阳性羊体温、胆固醇、血糖、总蛋白和各类型细胞含量及尿液中蛋白质、葡萄糖含量等指标与对照羊无显著差异(P>0.05);3)16S r DNA菌群测序结果表明,转基因阳性羊与对照羊肠道微生物群落组成及优势菌群均无显著差异(P>0.05);4)转基因阳性羊褪黑素含量显著高于对照羊(P<0.05),且乳中褪黑素含量显著高于血液(P<0.05),转基因阳性羊乳中乳蛋白和干物质含量显著高于对照羊(P<0.05),转基因阳性羊体细胞数显著低于对照羊(P<0.05)。说明乳腺过表达褪黑素合成限速酶ASMT基因不影响转基因奶山羊健康,而且会提高奶山羊乳品质。展开更多
Cellular energy metabolism correlates with cell fate,but the metabolic properties of chicken embryonic stem (chES) cells are poorly understood.Using a previously established chES cell model and electron microscopy (EM...Cellular energy metabolism correlates with cell fate,but the metabolic properties of chicken embryonic stem (chES) cells are poorly understood.Using a previously established chES cell model and electron microscopy (EM),we found that undifferentiated chES cells stored glycogen.Additionally,undifferentiated chES cells expressed lower levels of glucose transporter 1 (GLUT1) and phosphofructokinase (PFK) mRNAs but higher levels of hexokinase 1 (HK1) and glycogen synthase (GYS) mRNAs compared with control primary chicken embryonic fibroblast (CEF) cells,suggesting that chES cells direct glucose flux towards the glycogenic pathway.Moreover,we demonstrated that undifferentiated chES cells block gluconeogenic outflow and impede the accumulation of glucose-6-phosphate (G6P) from this pathway,as evidenced by the barely detectable levels of pyruvate carboxylase (PCX) and mitochondrial phosphoenolpyruvate carboxykinase (PCK2) mRNAs.Additionally,cell death occurred in undifferentiated chES cells as shown by Hoechst 33342 and propidium iodide (PI) double staining,but it could be rescued by exogenous G6P.However,we found that differentiated chES cells decreased the glycogen reserve through the use of PAS staining.Moreover,differentiated chES cells expressed higher levels of GLUT1,HK1 and PFK mRNAs,while the level of GYS mRNA remained similar in control CEF cells.These data indicate that undifferentiated chES cells continue to synthesize glycogen from glucose at the expense of G6P,while differentiated chES cells have a decreased glycogen reserve,which suggests that the amount of glycogen is indicative of the chES cell state.展开更多
Long-term in vitro maintenance of embryonic stem cell (ESC) pluripotency enables the pluripotency and differentiation of ESCs in animals to be investigated. The ability to successfully maintain and differentiate chick...Long-term in vitro maintenance of embryonic stem cell (ESC) pluripotency enables the pluripotency and differentiation of ESCs in animals to be investigated. The ability to successfully maintain and differentiate chicken embryonic stem cells (cESCs) would provide a useful tool for avian biology research and would be a resource directly applicable to agricultural production. In this study, endogenous chicken pluripotency transcription factors, POUV, Sox-2, Nanog and Lin28 were cloned and expressed as recombinant proteins containing a nine consecutive arginine protein transduction domain (PTD). cESCs were cultured with these recombinant proteins to maintain cESC pluripotency in vitro. Cultured cESCs exhibited typical characteristics of pluripotency, even after six generations of rapid doubling, including positive staining for stage-specific embryonic antigen I, and strong staining for alkaline phosphatase. Expression levels of the pluripotency markers, POUV, Nanog, C-Myc, Sox-2 and Lin28 were the same as in uncultured stage X blastoderm cells, and most significantly, the formation of embryoid bodies (EBs) by 6th generation cESCs confirmed the ability of these cultured cESCs to differentiate into cells of all three embryonic germ layers. Thus, transcription factors could be translocated through the cell membrane into the intracellular space of cESCs by using a PTD of nine consecutive arginines and the pluripotency of cESCs could be maintained in vitro for at least six generations.展开更多
Cloning by somatic nuclear transfer is an inefficient process in which many of the cloned ani- mals died shortly after birth and displayed organ ab- normalities. In an effort to determine the possible genetic causes o...Cloning by somatic nuclear transfer is an inefficient process in which many of the cloned ani- mals died shortly after birth and displayed organ ab- normalities. In an effort to determine the possible genetic causes of neonatal death and organ abnor- malities, we have examined expression patterns of four genes that modified chromatin (DNMT1, PCAF,MeCP2 and EED) in six organs (heart, liver, spleen, lung, kidney and brain) of both neonatal death cloned bovines (n=9) and normal control calves produced by artificial insemination (AI) using real-time quantitative RT-PCR. The effect of the age of the fibroblast donor cell on the gene expression profiles was also investigated. Aberrant expressions of DNMT1 and PCAF were found in some studied tissues, but the expression of MeCP2 and EED had similar levels to those of the normal controls. The expression of DNMT1 showed a higher level in heart, liver and brain of both cloned bovines. A higher ex- pression level of PCAF was seen in heart and liver of both cloned bovines, but a lower level was seen only in spleen of adult fibroblast (AF) cell-derived clones. Our results suggest that aberrant expression in gene that modified chromatins were found in cloned bovine tissues of neonatal death. Because DNMT1 and PCAF play an important role in DNA methylation and histone acetylation on nuclear chromatin respectively, and normal expression of DNMT1 and PCAF is needed for precious reprogramming of donor nuclear, the aberrant transcription patterns of DNMT1 andPCAF in these clones may contribute to the defects of organs reported in neonatal death of clones.展开更多
Somatic cell clone technology is a viable ap- proach to preserving endangered livestock and wildlife ge- netic resources. In the present research, somatic cell nuclear transfer (SCNT) was performed using granulose cel...Somatic cell clone technology is a viable ap- proach to preserving endangered livestock and wildlife ge- netic resources. In the present research, somatic cell nuclear transfer (SCNT) was performed using granulose cells from the critical endangered Chinese red-cross yellow cattle as donor cells. A total of 211 oocytes were manipulated and 166 (79%) of them were successfully enucleated. 112 (67.4%) SCNT embryos were reconstructed, 94 (83%) of them cleaved, and 48 (43%) of them developed to blastocyst stage. SCNT blastocysts were transferred to 6 Holstein recipients, and 2 (33%) of them were found to be pregnant. One of them maintained to term and delivered a calf, whereas another aborted. Effect of different fusion buffer (mannitol vs. Zim- merman fusion buffer) and different activation methods (calcium ionophore+6-DMAP vs. cycloheximide+CB) on fu- sion rate and development of SCNT embryos were investi- gated. The results indicated that: (i) on condition of two DC pulses of 2.5 kV/cm for 10 μs each, fusion rates were higher in mannitol solution than in Zimmerman fusion buffer (71% vs. 61%, respectively, p<0.05), but the blastocysts rates did not differ between two treatments (36% vs. 39%, p>0.05 ); (ii) There was no significant difference in development rates to the blastocyst stage for SCNT embryos activated by calcium ionophore+6-DMAP or by cycloheximide+CB (42% vs. 46%, respectively, p>0.05). Microsatellite DNA analysis examining 28 loci confirmed that the cloned calf was genetically identi- cal to the donor Jinan red-cross yellow cattle and different from the recipient females. Growth and reproductive per- formance of cloned cow were evaluated, and there were no difference i cross-red n it between cloned and normal control Jinan yellow cattle. Furthermore, the cloned yellow cow has delivered a healthy yellow calf.展开更多
文摘尽管新一代基因编辑技术CRISPR/Cas9拥有众多优点,但在执行单个碱基水平的突变时其效率往往很低。由于DNA的双链断裂具有很多的不确定性,又加上基于供体模板的同源末端重组(homology directed repair,HDR)仅仅发生在分裂活跃的细胞中,而非同源末端连接(non-homologous end joining,NHEJ)在整个细胞周期中都可以发生,因此,传统CRISPR/Cas9在单碱基分辨率上进行基因编辑时存在一定弊端。碱基编辑器(base editor,BE)的出现则在一定程度上弥补了这一缺陷。胞嘧啶碱基编辑器(cytosine base editor,CBE)或腺嘌呤碱基编辑器(adenine base editor,ABE)都能够在不引起双链断裂的情况下实现C·G到T·A或A·T到G·C的转换,极大地提高了单碱基编辑的应用价值。本文侧重对出现较早的CBE的原理、发展、应用及存在的问题进行综述,以期为高效单碱基突变工具在生物医学和畜牧业生产中的应用提供有益的参考和借鉴。
文摘为了研究乳腺过表达褪黑素合成限速酶乙酰血清素甲基转移酶(ASMT,HIOMT)基因奶山羊的生物安全性,试验针对乳腺过表达褪黑素合成酶ASMT基因奶山羊模型,记录了转基因山羊的生长发育数据、检测了血液及尿液中生理生化指标,并对肠道微生物、乳成分及褪黑素含量进行分析。结果表明:1)转基因阳性羊0,3,6,12月龄体重、体长、身高和胸围四项生长指标和对照羊均无显著差异(P>0.05);2)转基因阳性羊体温、胆固醇、血糖、总蛋白和各类型细胞含量及尿液中蛋白质、葡萄糖含量等指标与对照羊无显著差异(P>0.05);3)16S r DNA菌群测序结果表明,转基因阳性羊与对照羊肠道微生物群落组成及优势菌群均无显著差异(P>0.05);4)转基因阳性羊褪黑素含量显著高于对照羊(P<0.05),且乳中褪黑素含量显著高于血液(P<0.05),转基因阳性羊乳中乳蛋白和干物质含量显著高于对照羊(P<0.05),转基因阳性羊体细胞数显著低于对照羊(P<0.05)。说明乳腺过表达褪黑素合成限速酶ASMT基因不影响转基因奶山羊健康,而且会提高奶山羊乳品质。
基金supported by the National Basic Research Program of China (Grant No. 2006CB102100)the National Natural Science Foundation of China (Grant No. 30471234)
文摘Cellular energy metabolism correlates with cell fate,but the metabolic properties of chicken embryonic stem (chES) cells are poorly understood.Using a previously established chES cell model and electron microscopy (EM),we found that undifferentiated chES cells stored glycogen.Additionally,undifferentiated chES cells expressed lower levels of glucose transporter 1 (GLUT1) and phosphofructokinase (PFK) mRNAs but higher levels of hexokinase 1 (HK1) and glycogen synthase (GYS) mRNAs compared with control primary chicken embryonic fibroblast (CEF) cells,suggesting that chES cells direct glucose flux towards the glycogenic pathway.Moreover,we demonstrated that undifferentiated chES cells block gluconeogenic outflow and impede the accumulation of glucose-6-phosphate (G6P) from this pathway,as evidenced by the barely detectable levels of pyruvate carboxylase (PCX) and mitochondrial phosphoenolpyruvate carboxykinase (PCK2) mRNAs.Additionally,cell death occurred in undifferentiated chES cells as shown by Hoechst 33342 and propidium iodide (PI) double staining,but it could be rescued by exogenous G6P.However,we found that differentiated chES cells decreased the glycogen reserve through the use of PAS staining.Moreover,differentiated chES cells expressed higher levels of GLUT1,HK1 and PFK mRNAs,while the level of GYS mRNA remained similar in control CEF cells.These data indicate that undifferentiated chES cells continue to synthesize glycogen from glucose at the expense of G6P,while differentiated chES cells have a decreased glycogen reserve,which suggests that the amount of glycogen is indicative of the chES cell state.
基金assisted by the National Key Lab of Agro Biotechnology
文摘Long-term in vitro maintenance of embryonic stem cell (ESC) pluripotency enables the pluripotency and differentiation of ESCs in animals to be investigated. The ability to successfully maintain and differentiate chicken embryonic stem cells (cESCs) would provide a useful tool for avian biology research and would be a resource directly applicable to agricultural production. In this study, endogenous chicken pluripotency transcription factors, POUV, Sox-2, Nanog and Lin28 were cloned and expressed as recombinant proteins containing a nine consecutive arginine protein transduction domain (PTD). cESCs were cultured with these recombinant proteins to maintain cESC pluripotency in vitro. Cultured cESCs exhibited typical characteristics of pluripotency, even after six generations of rapid doubling, including positive staining for stage-specific embryonic antigen I, and strong staining for alkaline phosphatase. Expression levels of the pluripotency markers, POUV, Nanog, C-Myc, Sox-2 and Lin28 were the same as in uncultured stage X blastoderm cells, and most significantly, the formation of embryoid bodies (EBs) by 6th generation cESCs confirmed the ability of these cultured cESCs to differentiate into cells of all three embryonic germ layers. Thus, transcription factors could be translocated through the cell membrane into the intracellular space of cESCs by using a PTD of nine consecutive arginines and the pluripotency of cESCs could be maintained in vitro for at least six generations.
基金This work was supported by the Biology Program of Chinese National Foundation of"863"(Grant No.2001AA213091)by the Major Program of Natural Science Foundation of Beijing(Grant No.5030001).
文摘Cloning by somatic nuclear transfer is an inefficient process in which many of the cloned ani- mals died shortly after birth and displayed organ ab- normalities. In an effort to determine the possible genetic causes of neonatal death and organ abnor- malities, we have examined expression patterns of four genes that modified chromatin (DNMT1, PCAF,MeCP2 and EED) in six organs (heart, liver, spleen, lung, kidney and brain) of both neonatal death cloned bovines (n=9) and normal control calves produced by artificial insemination (AI) using real-time quantitative RT-PCR. The effect of the age of the fibroblast donor cell on the gene expression profiles was also investigated. Aberrant expressions of DNMT1 and PCAF were found in some studied tissues, but the expression of MeCP2 and EED had similar levels to those of the normal controls. The expression of DNMT1 showed a higher level in heart, liver and brain of both cloned bovines. A higher ex- pression level of PCAF was seen in heart and liver of both cloned bovines, but a lower level was seen only in spleen of adult fibroblast (AF) cell-derived clones. Our results suggest that aberrant expression in gene that modified chromatins were found in cloned bovine tissues of neonatal death. Because DNMT1 and PCAF play an important role in DNA methylation and histone acetylation on nuclear chromatin respectively, and normal expression of DNMT1 and PCAF is needed for precious reprogramming of donor nuclear, the aberrant transcription patterns of DNMT1 andPCAF in these clones may contribute to the defects of organs reported in neonatal death of clones.
基金This work was supported by“863” High-Tech Research and Development Program (Grant No. 2001AA213091 & 2002AA206111) Natural Science Foundation of Bejjing (Grant No. 5030001 ).
文摘Somatic cell clone technology is a viable ap- proach to preserving endangered livestock and wildlife ge- netic resources. In the present research, somatic cell nuclear transfer (SCNT) was performed using granulose cells from the critical endangered Chinese red-cross yellow cattle as donor cells. A total of 211 oocytes were manipulated and 166 (79%) of them were successfully enucleated. 112 (67.4%) SCNT embryos were reconstructed, 94 (83%) of them cleaved, and 48 (43%) of them developed to blastocyst stage. SCNT blastocysts were transferred to 6 Holstein recipients, and 2 (33%) of them were found to be pregnant. One of them maintained to term and delivered a calf, whereas another aborted. Effect of different fusion buffer (mannitol vs. Zim- merman fusion buffer) and different activation methods (calcium ionophore+6-DMAP vs. cycloheximide+CB) on fu- sion rate and development of SCNT embryos were investi- gated. The results indicated that: (i) on condition of two DC pulses of 2.5 kV/cm for 10 μs each, fusion rates were higher in mannitol solution than in Zimmerman fusion buffer (71% vs. 61%, respectively, p<0.05), but the blastocysts rates did not differ between two treatments (36% vs. 39%, p>0.05 ); (ii) There was no significant difference in development rates to the blastocyst stage for SCNT embryos activated by calcium ionophore+6-DMAP or by cycloheximide+CB (42% vs. 46%, respectively, p>0.05). Microsatellite DNA analysis examining 28 loci confirmed that the cloned calf was genetically identi- cal to the donor Jinan red-cross yellow cattle and different from the recipient females. Growth and reproductive per- formance of cloned cow were evaluated, and there were no difference i cross-red n it between cloned and normal control Jinan yellow cattle. Furthermore, the cloned yellow cow has delivered a healthy yellow calf.
