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Search Results: 1 - 10 of 5007 matches for " Zhengxing Lian "
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Affine transformation with zero entropy and nilsystems
Zhengxing Lian
Mathematics , 2015,
Abstract: In this paper, we study affine transformations on tori, nilmanifolds and compact abelian groups. For these systems, we show that an equivalent condition for zero entropy is the orbit closure of each point has a nice structure. To be precise, the affine systems on those spaces are zero entropy if and only if the orbit closure of each point is isomorphic to an inverse limit of nilsystems.
Weakly mixing, proximal topological models for ergodic systems and applications
Zhengxing Lian,Song Shao,Xiangdong Ye
Mathematics , 2014,
Abstract: In this paper it is shown that every non-periodic ergodic system has two topologically weakly mixing, fully supported models: one is non-minimal but has a dense set of minimal points; and the other one is proximal. Also for independent interests, for a given Kakutani-Rokhlin tower with relatively prime column heights, it is demonstrated how to get a new taller Kakutani-Rokhlin tower with same property, which can be used in Weiss's proof of the Jewett-Krieger's theorem and the proofs of our theorems. Applications of the results are given.
Effects of Different CO2 Levels on Chicken Embryonic Development During Early Stage of Incubation
Hongbing Han,Xiang Li,Kun Yu,Zhengxing Lian
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2011.2624.2630
Abstract: During the early stage of incubation of chicken eggs, different CO2 concentrations play an important role in the embryonic and postnatal growth. However, the mechanism involved in this process is still not well clarified. In this study, chicken eggs were incubated under different CO2 concentration levels (0.03-0.05, 2, 5 and 10%) during the 1st 4 days of incubation and measured of several embryo growth parameters. It was then found that higher CO2 concentration significantly played down the albumen pH value after 2 days of incubation and the embryo weight and length, diameter of area vasculosa of yolk sac and number of somite all decreased with the increasing of CO2 level. Compared with the mortality (3.23%) and abnormality (0%) in the control group, the corresponding percentages in three treatment groups were much higher with the lowest at 17 and 29%, respectively. Taking the two sides together, it might be well concluded that high CO2 concentration during the 1st 4 days of egg incubation inhibited chicken embryonic development through the lowering of albumen pH value.
Sequences from zero entropy noncommutative toral automorphisms and Sarnak Conjecture
Wen Huang,Zhengxing Lian,Song Shao,Xiangdong Ye
Mathematics , 2015,
Abstract: In this paper we study $C^*$-algebra version of Sarnak Conjecture for noncommutative toral automorphisms. Let $A_\Theta$ be a noncommutative torus and $\alpha_\Theta$ be the noncommutative toral automorphism arising from a matrix $S\in GL(d,\mathbb{Z})$. We show that if the Voiculescu-Brown entropy of $\alpha_{\Theta}$ is zero, then the sequence $\{\rho(\alpha_{\Theta}^nu)\}_{n\in \mathbb{Z}}$ is a sum of a nilsequence and a zero-density-sequence, where $u\in A_\Theta$ and $\rho$ is any state on $A_\Theta$. Then by a result of Green and Tao, this sequence is linearly disjoint from the M\"obius function.
Four recombinant pluripotency transcriptional factors containing a protein transduction domain maintained the in vitro pluripotency of chicken embryonic stem cells
MiaoYing Yu,Song Lian,HongBing Han,Kun Yu,GuiGuan Li,ZhengXing Lian,Ning Li
Science China Life Sciences , 2013, DOI: 10.1007/s11427-012-4426-4
Abstract: 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.
Construction of a 7-fold BAC library and cytogenetic mapping of 10 genes in the giant panda (Ailuropoda melanoleuca)
Wei Liu, Yonghui Zhao, Zhaoliang Liu, Ying Zhang, Zhengxing Lian, Ning Li
BMC Genomics , 2006, DOI: 10.1186/1471-2164-7-294
Abstract: This BAC library contains 198,844 clones with an average insert size of 108 kb, which represents approximately seven equivalents of the giant panda haploid genome. Screening the library with 15 genes and 8 microsatellite markers demonstrates that it is representative and has good genome coverage. Furthermore, ten BAC clones harbouring AGXT, GHR, FSHR, IRBP, SOX14, TTR, BDNF, NT-4, LH and ZFX1 were mapped to 8 pairs of giant panda chromosomes by fluorescence in situ hybridization (FISH).This is the first large-insert genomic DNA library for the giant panda, and will contribute to understanding this endangered species in the areas of genome sequencing, physical mapping, gene cloning and comparative genomic studies. We also identified the physical locations of ten genes on their relative chromosomes by FISH, providing a preliminary framework for further development of a high resolution cytogenetic map of the giant panda.The giant panda is an endangered animal with a restricted habitat in South-western China. A survey revealed that only about 1,600 individuals remain in the wild [1]. The highly specialized reproductive behaviour [2] and low fertility make it difficult to increase their numbers quickly by breeding in captivity. In recent years, strenuous efforts have been made to protect this animal and considerable knowledge of its physiology, biochemistry, genetic diversity and ecology has been achieved, but research on the giant panda genome is still rare. So far only a few genes have been cloned and two have been mapped to specific giant panda chromosomes [3,4].A bacterial artificial chromosome (BAC) library is a powerful tool for studying genomes. Compared with yeast artificial chromosome (YAC) clones, BAC clones have many advantages such as high stability, easy manipulation and rare chimerism [5,6]. BAC libraries of human [7] and major livestock [8-11] have been constructed and widely used, but no such large-insert genomic DNA library has been reported to date for
Metabolic properties of chicken embryonic stem cells
Jia Li,BaoLu Zhang,HongBing Han,ZhiCheng Cao,ZhengXing Lian,Ning Li
Science China Life Sciences , 2010, DOI: 10.1007/s11427-010-4055-8
Abstract: 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.
Effects of different states of sheep fetal fibroblasts as donor cells on the early development in vitro of reconstructed sheep embryos
Hai Wang,Hong Ao,QiuZhen Pan,RongQi Li,MengBin Zhao,ZhengXing Lian,Ning Li,ChangXin Wu
Science China Life Sciences , 2007, DOI: 10.1007/s11427-007-0013-5
Abstract: To investigate the effects of different states of donor cells on the development of reconstructed sheep embryos, we designed five treatments of donor cells, including cell passage, cell size, serum starvation, colchicine treatment and gene transfection. Results are as follows: (I) Compared with 16–18 passage cells, the morula/blastocyst rate of 5–7 passage cells as donor nuclei was significantly higher (17.3% vs. 4.9%, P<0.05), suggesting the advantage of short-time cultured cells in supporting the development of reconstructed embryos. (II) The mourla/blastocyst rate of reconstructed embryos derived from medium cells (15–25 μm) as donor nuclei was higher than that from large cells (25–33 μm) and small cells (8–15 μm)(20.0% vs. 8.0%, 9.7%), indicating that reconstructed embryos from medium cells had a greater potentiality to develop into morula/blastocysts than those from small or large ones. (III) The morula/blastocyst rate of reconstructed embryos from donor cells of SS (serum starvation) was lower than that from donor cells of NSS (non-serum starvation), but no significant difference was detected between SS and NSS(11.8% vs. 18.6%, P>0.05). (IV) Fetal fibroblasts treated with 0.05 μmol/L colchicine exhibited a higher morula/blastocyst rate of reconstructed embryos than those treated with 0.10 μmol/L colchicine and untreated ones (27.5% vs. 12.1%, 17.1%), however, no significant difference among the three treatments was detected (P>0.05). (V) The morula/blastocyst rate of reconstructed embryos from fetal fibroblasts transfected with GFP gene only was 3.1%, significantly lower than that from non-transgenic cells (3.1% vs. 20.4%, P<0.05). In conclusion, our results demonstrated that fetal fibroblasts of fewer passages, medium size could ensure a higher morula/blastocyst rate of reconstructed embryos. Serum starvation of donor cells might be unnecessary to the development of reconstructed embryos. Donor cells treated with 0.05 μmol/L colchicine could facilitate the development of reconstructed embryos. Additionally, as cells transfected with GFP gene were used as donor nuclei, adverse effect on the development of reconstructed embryos was observed. Therefore, the developmental efficiency of reconstructed embryos could be improved if proper treatments to donor cells were used.
Single nucleotide polymorphism analysis on chicken extracelluar fatty acid binding protein gene and its associations with fattiness trait
Qigui Wang,Ning Li,Xuemei Deng,Zhengxing Lian,Hui Li,Changxin Wu
Science China Life Sciences , 2001, DOI: 10.1007/BF02879610
Abstract: Fattiness is an important parameter to estimate meat quality, which has high heritability. In this experiment, F2 chickens derived from Broilers crossing to Silky were used to study the effect of extracellular fatty acid binding protein (EX-FABP) gene on abdominal fat accumulation. 1.6 kb of the 5′ region of the gene was amplified by six pairs of primers, and then single nucleotide polymorphisms (SNPs) were detected by the technique of single strand conformation polymorphism (SSCP) and then confirmed by sequencing. There were four nucleotides variations found, A-G at-1807, C-A at -1805, T-C at -1011 and a C insertion at -1000 respectively. The result of least square analysis suggests that the birds with BB genotype defined by the second pair of primer have a higher abdominal fat weight and abdominal fat percentage than the birds with the other genotypes (AA and AB). It implied that EX-FABP gene could be a candidate locus or linked to a major gene to significantly affect abdominal fat traits in chicken.
Changes in the Relative Inflammatory Responses in Sheep Cells Overexpressing of Toll-Like Receptor 4 When Stimulated with LPS
Shoulong Deng, Qian Wu, Kun Yu, Yunhai Zhang, Yuchang Yao, Wenting Li, Zhuo Deng, Guoshi Liu, Wu Li, Zhengxing Lian
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047118
Abstract: Background Many groups of Gram-negative bacteria cause diseases harmful to sheep. TLR4 is an important Toll-like receptor (TLR) which responds to common Gram-negative bacterial infections. Activation of TLR4 leads to the induction of inflammatory responses, which is a linkage between the innate and adaptive immune systems. A vector pTLR4-3S was constructed to overexpress TLR4 gene in sheep. In this study, effects of TLR4 overexpression on inflammation response under LPS stimulated were addressed in vivo and in vitro. Methodology/Principal Findings Sheep fetal fibroblasts were transfected with expression vector pTLR4-3S. Transgenic sheep were produced by microinjection of the constructed plasmids into fertilized eggs. Fetal fibroblasts, monocyte-macrophage and fibroblasts isolated from the transgenic sheep were stimulated by LPS. After that immunoactive factors (TNF-α, IL-10, IL-6, IL-8, IFN-γ), nitric oxide, phagocytize ability and adhesion were detected. Furthermore, transgenic sheep were intradermal injected of LPS in ear and observed pathological changes by HE strain. Overexpression of TLR4 gene was observed on transgenic cells and individuals. In vitro, TLR4 overexpression transgenic cells secreted Th1 and Th2 inducing cytokines with a strong LPS mediated inflammation response and promoting the secretion of nitric oxide, and then recovered to initial level. The phagocytosis index of monocyte/macrophage in transgenic sheep was higher than that of non-transgenic sheep (P<0.05). In vivo, tissue sections showed that transgenic individuals launched inflammation response more quickly. Conclusions/Significance Overexpression of TLR4 in transgenic sheep enhanced the clearance of invaded microbe through secretion of cytokines, activation of macrophage, oxidation damage and infiltration of neutrophil.
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