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T Tian

Publications and source records attributed to T Tian.

At least 19 recordsLinked to original sources
PubMed2006

Nodal signals pattern vertebrate embryos.

Vertebrate embryonic patterning requires several conserved inductive signals-including Nodal, Bmp, Wnt and Fgf signals. Nodal, which is a member of the transforming growth factor beta (TGFbeta) superfamily, activates a signal transduction pathway that is similar to that of other TGFbeta members. Nodal genes, which have been identified in numerous vertebrate species, are expressed in specific cell types and tissues during embryonic development. Nodal signal transduction has been shown to play a pivotal role in inducing and patterning mesoderm and endoderm, and in regulating neurogenesis and left-right axis asymmetry. Antagonists, which act at different steps in the Nodal signal transduction pathway, have been shown to tightly modulate the inductive activity of Nodal.

Animals↗
PubMed2005

The Lettuce infectious yellows virus (LIYV)-encoded P26 is associated with plasmalemma deposits within LIYV-infected cells.

Cytological, immunological, and mutagenesis approaches were used to identify the viral factors associated with the formation of plasmalemma deposits (PLDs) in whole plants and protoplasts infected by Lettuce infectious yellows virus (LIYV). Transmission electron microscopy and immunogold labeling using polyclonal antibodies to four of the five LIYV RNA 2-encoded large proteins, capsid protein (CP), minor capsid protein (CPm), HSP70 homolog (HSP70h), and P59, showed specific labeling of LIYV virions or virion aggregates around the vesiculated membranous inclusions, but not PLDs in LIYV-infected Nicotiana benthamiana, Nicotiana clevelandii, Lactuca sativa, and Chenopodium murale plants, and Nicotiana tabacum protoplasts. In contrast, antibodies to the RNA 2-encoded P26 showed specific labeling of PLDs but not virions in both LIYV-infected plants and protoplasts. Virion-like particles (VLPs) were seen in protoplasts infected by all LIYV RNA 2 mutants except for the CP (major capsid protein) mutant. PLDs were more difficult to find in protoplasts, but were seen in protoplasts infected by the CP and CPm mutants, but not in protoplasts infected by the P26, HSP70h, or P59 mutants. Interestingly, although the CPm mutant showed VLPs and PLDs, the PLDs did not show associated virions/virion-like particles as was always observed for PLDs seen in protoplasts infected by wild-type LIYV. Immunoblot analyses performed on purified LIYV virions showed that P26 was not detected with purified virions, but was detected in the cell wall, 1000 g and 30,000 g pellet fractions of LIYV-infected plants. These data suggest that P26 is associated with the LIYV-induced PLDs, and in contrast to the other RNA 2-encoded large proteins, P26 is not a virion protein.

Base Sequence↗
PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗
PubMed2001

Green fluorescent protein expression from recombinant lettuce infectious yellows virus-defective RNAs originating from RNA 2.

Lettuce infectious yellows virus (LIYV) RNA 2 defective RNAs (D RNAs) were compared in protoplasts for their ability to replicate and to express the green fluorescent protein (GFP) from recombinant D RNA constructs. Initially four LIYV D RNAs of different genetic composition were compared, but only two (LIYV D RNA M5 and M18) replicated to high levels. Both of these contained at least two complete ORFs, one being the 3'-terminal ORF encoding P26. Northern hybridization analysis using probes corresponding to 3' regions of LIYV RNA 2 detected the P26 subgenomic RNA from protoplasts infected with LIYV RNAs 1 and 2 or protoplasts inoculated only with RNA 1 plus either the LIYV D RNA M5 or M18, suggesting that these LIYV D RNAs served as templates to generate the P26 subgenomic RNA. The GFP coding region was inserted as an in-frame insertion into the P26 coding region of the LIYV M5 and M18 D RNAs, yielding M5gfp and M18gfp. When transcripts of M5gfp and M18gfp were used to inoculate protoplasts, bright fluorescence was seen only when they were co-inoculated with LIYV RNA 1. The percentage of fluorescent protoplasts ranged from experiment to experiment, but was as high as 5.8%. Time course analyses showed that fluorescence was not detected before 48 h pi, and this correlated with the timing of LIYV RNA 2 and RNA 2 D RNA accumulation, but not with that of LIYV RNA 1.

Blotting, Northern↗
PubMed2001

Heterogeneity within medullary-type TCRalphabeta(+)CD3(+)CD4(-)CD8(+) thymocytes in normal mouse thymus.

The functional maturation process of medullary-type CD4(-)CD8(+) [CD8 single-positive (SP)] thymocytes remains largely uncharacterized. We describe a phenotypic analysis of CD8 SP medullary-type thymocytes and find a remarkable heterogeneity within this thymic cell population. While mature CD8(+) T cells in the periphery are relatively homogeneous (TCRalphabeta(+)CD3(+)Qa-2(+) HSA(-)3G11(-)6C10(-)CD69(-)), CD8 SP medullary-type thymocytes contain discrete subpopulations that can be identified by differential expression of several cell-surface markers. We have identified at least six discrete subpopulations in the subset of TCRalphabeta(+)CD3(+) CD8 SP cells in the thymus. According to the expressed phenotypes, a linear developmental pathway is predicted among these CD8 SP subpopulations as follows: 6C10(+)CD69(+)HSA(hi)3G11(+)Qa-2(-) --> 6C10(-)CD69(+)HSA(hi/int)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(int)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(lo)3G11(+)Qa-2(-) --> 6C10(-)CD69(-)HSA(-/lo)3G11(-)Qa-2(-) --> 6C10(-)CD69(-)HSA(-/lo)3G11(-)Qa-2(+). This study provides a framework for understanding CD8 SP T cell maturation in the thymic medulla.

Animals↗
PubMed2001

Apoptosis in atrophic skeletal muscle induced by brachial plexus injury in rats.

BACKGROUND: Skeletal muscle atrophy induced by denervation is associated with apoptosis. This study was undertaken to determine the role of apoptosis and the expression of apoptosis-associated genes in rat skeletal muscle made atrophic by brachial plexus injury, and to study the apoptotic signal transduction pathway. METHODS: An animal model of skeletal muscle atrophy was established in rats by severing the brachial plexus of one forelimb. Apoptosis of muscle cells was investigated with terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate end labeling, flow cytometry, deoxyribonucleic acid (DNA) electrophoresis, and electron microscopy. The apoptosis-associated genes Fas, FADD, Caspase 8, c-myc, p53, and Bcl-2 were detected by immunohistochemistry and Northern blot. RESULTS: By terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate end labeling and flow cytometry we found that the percentage of apoptotic muscle cells was higher in atrophic than in healthy skeletal muscle (p < 0.05). DNA laddering could be seen in gel electrophoresis of DNA from atrophic muscle. By electron microscopy, we observed morphologic change of early apoptosis, such as aggregation of chromosomes, expansion of nucleic cistern, and contraction of the nucleus. Using immunohistochemistry, we determined that in atrophic muscle Fas, FADD, and Caspase-8 genes were highly expressed, whereas Bcl-2 was poorly expressed (p < 0.01). However, we did not detect a change in the expression of p53 or c-myc genes. Northern blots indicated that Fas messenger ribonucleic acid was higher and Bcl-2 messenger ribonucleic acid was lower in atrophic than in healthy muscle (p < 0.01). CONCLUSION: There are many more apoptotic cells in muscle atrophied as a result of brachial plexus injury than in healthy muscle, and apoptosis plays an important role in the pathogenesis of atrophy. The apoptotic signal may be transmitted from Fas to FADD to Caspase-8, with a decrease in Bcl-2 expression aggravating the process.

Animals↗
PubMed2000

A heterogeneous population of defective RNAs is associated with lettuce infectious yellows virus.

Preparations of dsRNAs and virion RNAs extracted from Nicotiana clevelandii plants infected with the bipartite Lettuce infectious yellows virus (LIYV) were found to contain multiple LIYV RNA species. In addition to the two LIYV genomic RNAs, three types of RNAs were observed: (a) 3' coterminal subgenomic RNAs; (b) RNAs containing LIYV RNA 1 or RNA 2 5' terminus but lacking the 3' terminus; and (c) RNAs with both LIYV RNA 2 3' and 5' termini but each with a central extensive deletion, a structure typical of defective RNAs (D RNAs). No D RNA-like RNAs were detected for LIYV RNA 1. A reverse transcription followed by polymerase chain reaction (RT-PCR) strategy was used to clone from virion RNAs several LIYV RNA 2 D RNAs as cDNAs. Nucleotide sequence analysis of 43 cloned cDNAs showed in some D RNAs the presence of a stretch of 1-5 nt in the junction site that is repeated in the genomic RNA 2 in the two positions flanking the junction site or in close proximity. Some D RNAs contained in the junction site one or several extra nucleotides not present in the LIYV genomic RNA 2. Two of the cloned cDNAs were used to generate in vitro transcripts, and infectivity studies showed that both D RNAs were replication competent in protoplasts when coinoculated with LIYV RNAs 1 and 2 or with only LIYV RNA1. Neither D RNA showed obvious effects upon LIYV RNA 1 and RNA 2 accumulation in coinfected protoplasts. These data suggest that LIYV infections contain a heterogeneous population of LIYV RNA 2 D RNAs, and some are encapsidated into virions.

Blotting, Northern↗
PubMed2000

T-cell killing of heterogenous tumor or viral targets with bispecific chimeric immune receptors.

We have previously described several novel chimeric immune receptors (CIRs) that redirect human T cells to kill malignant or HIV-infected cells. These CIRs comprise a cancer- or virus-specific ligand or single-chain antibody fused to the signaling domain of the T-cell receptor CD3-zeta subunit. Binding of the ligand- or antibody-based CIR to the target antigen (Ag) triggers T-cell-mediated cytolysis of the tumor- or virus-infected cell independent of target cell major histocompatibility complex class I expression. A new type of CIR was developed to mediate the lysis of cells that expressed one or more distinct viral or tumor Ags; three bispecific CIRs (BCIRs) were generated that recognized the carcinoembryonic Ag (CEA) and TAG-72 tumor Ags or, alternatively, distinct epitopes in the HIV envelope (HIVenv). T cells expressing the antitumoral Ag BCIR lysed both CEA- and TAG-72-expressing targets and did not kill Ag-negative targets or target cells expressing other members of the CEA family. Similarly, T cells expressing the anti-HIVenv BCIR lysed target cells expressing both the wild-type HIVenv and a mutant HIVenv that lacked the epitopes recognized by the monospecific CIRs. This approach permits the generation of T cells with a broader spectrum of activity capable of killing virus-infected cells and malignant cells and reduces the potential of progression of disease due to Ag loss variants.

Amino Acid Sequence↗
PubMed2000

Asynchronous accumulation of lettuce infectious yellows virus RNAs 1 and 2 and identification of an RNA 1 trans enhancer of RNA 2 accumulation.

Time course and mutational analyses were used to examine the accumulation in protoplasts of progeny RNAs of the bipartite Crinivirus, Lettuce infectious yellow virus (LIYV; family Closteroviridae). Hybridization analyses showed that simultaneous inoculation of LIYV RNAs 1 and 2 resulted in asynchronous accumulation of progeny LIYV RNAs. LIYV RNA 1 progeny genomic and subgenomic RNAs could be detected in protoplasts as early as 12 h postinoculation (p.i.) and accumulated to high levels by 24 h p.i. The LIYV RNA 1 open reading frame 2 (ORF 2) subgenomic RNA was the most abundant of all LIYV RNAs detected. In contrast, RNA 2 progeny were not readily detected until ca. 36 h p.i. Mutational analyses showed that in-frame stop codons introduced into five of seven RNA 2 ORFs did not affect accumulation of progeny LIYV RNA 1 or RNA 2, confirming that RNA 2 does not encode proteins necessary for LIYV RNA replication. Mutational analyses also supported that LIYV RNA 1 encodes proteins necessary for replication of LIYV RNAs 1 and 2. A mutation introduced into the LIYV RNA 1 region encoding the overlapping ORF 1B and ORF 2 was lethal. However, mutations introduced into only LIYV RNA 1 ORF 2 resulted in accumulation of progeny RNA 1 near or equal to wild-type RNA 1. In contrast, the RNA 1 ORF 2 mutants did not efficiently support the trans accumulation of LIYV RNA 2. Three distinct RNA 1 ORF 2 mutants were analyzed and all exhibited a similar phenotype for progeny LIYV RNA accumulation. These data suggest that the LIYV RNA 1 ORF 2 encodes a trans enhancer for RNA 2 accumulation.

Base Sequence↗
PubMed2000

[Apoptosis in atrophic skeletal muscle induced by brachial plexus injury in rats].

OBJECTIVE: To study the role of apoptosis and the expression of apoptosis-associated genes in skeletal muscle atrophy induced by brachial plexus injury in rats. METHODS: Rat models of skeletal muscle atrophy were established by cutting off brachial plexus of one upper limb. Apoptosis of muscular cells was investigated by TUNEL, flowcytometry, DNA electrophoresis and electromicroscopic observation. The apoptosis associated genes such as Fas, FADD, Caspase 8, c-myc, P53 and Bcl-2 were detected by immunohistochemical method (ABC) and Northern-blot. RESULTS: It was found with TUNEL and flowcytometry that the percentage of apoptotic muscle cell rose obviously in atrophic skeletal muscle (P < 0.05). DNA laddering could be seen in DNA gel electrophoresis of atrophic muscle after brachial injury. Morphologic changes of early stage in apoptotic cell could be seen under eletcromicroscope, such as the aggregation of chromosome, the expansion of nucleic cistern and the contraction of nucleus. Fas, FADD and Caspase genes were expressed highly and Bcl-2 gene was expressed lowly with immunohistochemical method in atrophic muscle. The results were all significantly different with that of the controls (P < 0.01). But the expression changes in P53 and c-myc genes were not obvious. The result of Northern-blot indicated that the mRNA of Fas gene rose and that of Bcl-2 gene decreased obviously (P < 0.01) in atrophic muscle induced by brachial plexus injury. CONCLUSION: There are much more apoptotic cells in atrophic muscle induced by brachial plexus injury, and apoptosis plays an important role in its pathogenesis. The apoptotic signal maybe transmitted through Fas-->FADD-->Caspase 8, and the decrease in Bcl-2 gene expression aggravates the process.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Lettuce infectious yellows virus: in vitro acquisition analysis using partially purified virions and the whitefly Bemisia tabaci.

Virions of lettuce infectious yellows virus (LIYV; genus Crinivirus) were purified from LIYV-infected plants and their protein composition was analysed by SDS-PAGE and immunoblotting. Virion preparations contained the major capsid protein (CP), but the minor capsid protein (CPm), p59 and the HSP70 homologue were also identified by immunoblot analysis. Immunogold labelling analysis showed that CP constituted the majority of the LIYV virion capsid, but CPm was also part of the capsid and localized to one end of the virion, similar to the polar morphology seen for viruses in the genus Closterovirus. p59 and the HSP70 homologue were not detected on virions by immunogold labelling, but were always detected in virion preparations by immunoblot analysis. Purified LIYV virions were used for in vitro acquisition analysis with Bemisia tabaci whiteflies and were efficiently transmitted to plants. Infectivity neutralization analyses were done using antisera to the LIYV-encoded CP, CPm, p59 and HSP70 homologue. Only antiserum to the CPm effectively neutralized LIYV transmission by B. tabaci. These data suggest that the LIYV-B. tabaci transmission determinants are associated with purified virions, and that the LIYV virion structural protein CPm is involved in transmission by B. tobaci.

Animals↗
PubMed1998

Development of tryptophan-modified human serum albumin columns for site-specific studies of drug-protein interactions by high-performance affinity chromatography.

Human serum albumin (HSA) is one of the main proteins involved in the binding of drugs and small solutes in blood or serum. This study examined the changes in chromatographic properties that occur for immobilized HSA following the chemical modification of HSA's lone tryptophan residue (Trp-214). Trp-214 was reacted with o-nitrophenylsulfenyl chloride, followed by immobilization of the modified protein and normal HSA onto separate silica-based HPLC supports. The binding properties of the modified and normal HSA were then analyzed and compared by using frontal analysis and zonal elution experiments employing R/S-warfarin and L-tryptophan as probe compounds for the warfarin and indole binding regions of HSA. The modified HSA was found to have the same number of binding sites as normal HSA for R-warfarin and L-tryptophan but lower association equilibrium constants for these test solutes. Zonal elution studies with R- and S-warfarin on the modified HSA column demonstrated the importance of Trp-214 in determining the stereoselective binding of HSA for these agents. These studies also indicated that tryptophan modification can alter HSA-based separations for chiral solutes.

Apazone↗
PubMed1998

Specific inclusion bodies are associated with replication of lettuce infectious yellows virus RNAs in Nicotiana benthamiana protoplasts.

Nicotiana benthamiana mesophyll protoplasts, either mock-inoculated or inoculated using in vitro transcripts derived from lettuce infectious yellows virus (LIYV) RNA 1- and/or RNA 2-cloned cDNAs were analysed by transmission electron microscopy (TEM) and, in some cases, also by immunogold labelling. TEM revealed the main cytopathological effects of LIYV infections in N. benthamiana protoplasts infected with RNAs 1 and 2: (a) typical closterovirus-induced (beet yellows virus-type) accumulations of vesiculated cytoplasmic membranes as inclusion bodies, sometimes with associated virions; (b) scattered aggregations of virions within the cytoplasm; and (c) electron-dense plasmalemma deposits. These were not seen in mock-inoculated protoplasts. Protoplasts inoculated only with LIYV RNA 1 contained vesiculated cytoplasmic inclusion bodies, but not virions or plasmalemma deposits. Thus, infection by only LIYV RNA 1 is sufficient to induce characteristic closterovirus vesiculated cytoplasmic inclusion bodies. However, both LIYV RNAs 1 and 2 are needed for production of virions and plasmalemma deposits.

Closterovirus↗
PubMed1998

[Antivirus effect of polysaccharides of brewer yeast in vitro].

The antivirus effect of polysaccharides of brewer yeast from yeast mud on 13 kinds of viruses including DNA and RNA virus along with their mechanisms were studied. The result showed that this effect was remarkable on the infections with poliovirus III, adenovirus III, ECHO6 virus, enterovirus 71, vesicular stomatitis virus, herpesvirus I, II, coxsackie A16 virus and coxsackie B3 virus. The polysaccharides of brewer yeast could also inhibit the development of cytopathic effect(CPE) and protect cultural cells from being infected with the above viruses.

Adenoviruses, Human↗
PubMed1995

Beet western yellows luteovirus capsid proteins produced by recombinant baculoviruses assemble into virion-like particles in cells and larvae of Bombyx mori.

We subcloned various constructs of the beet western yellows luteovirus (BWYV) 3' proximal genes into Bombyx mori nuclear polyhedrosis virus (BmNPV) transfer vectors and constructed recombinant BmNPVs. The recombinant BmNPVs were used to infect BmN cells and B. mori larvae. Protein expression was analyzed by SDS-PAGE and immunoblot analysis, and the BWYV-encoded capsid protein (CP), P19, readthrough protein (RT), and a modified capsid-readthrough protein (CP-RT*) were detected in BmN cells infected by the respective BmNPVs. However, we detected only the BWYV CP and P19 in BmN cells infected with a recombinant BmNPV containing all three BWYV 3' proximal genes. BmN cells and fat body cells from B. mori larvae infected with recombinant BmNPVs were analyzed by transmission electron microscopy and immunogold labeling. Particles which morphologically and serologically resembled BWYV virions were detected in the nuclei of BmN cells and B. mori larval fat body cells infected with recombinant BmNPVs producing either the BWYV CP alone or BWYV CP plus a BWYV CP-RT*. Similar particles were not detected in cells infected with a control BmNPV or recombinant BmNPV producing only CP-RT*.

Animals↗