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Li Ren

Publications and source records attributed to Li Ren.

At least 19 recordsLinked to original sources
PubMed2026

RNAi in the Rhizarian Phytopathogen Plasmodiophora brassicae: The Causal Agent of Clubroot Disease in Cruciferous Crops.

Although RNA interference (RNAi) is widespread and functionally important across eukaryotes, RNAi pathways are diverse or even lost in some lineages. Rhizaria represents a major and distinct eukaryotic supergroup that includes Plasmodiophora brassicae (Pb), the causal agent of cruciferous clubroot disease, yet RNAi in this lineage remains poorly understood. Here, we characterized an unusual RNAi pathway in Pb. Small RNA sequencing across five representative Pb life stages revealed abundant siRNAs and miRNAs characterized by a predominant 21-nt length, phased genomic distribution, 2-nt 3' overhangs, and a strong 5'-cytidine bias. Three Pb miRNAs were further validated by northern blotting and stem-loop RT-qPCR. Genome analysis identified two canonical AGO homologs, PbAGO1 and PbAGO2, but no Dicer homologs, except for an RNase III-containing Drosha-like protein, PbDRL. Functional analyses showed that PbAGO1 and PbAGO2 mediate gene silencing, whereas PbDRL is required for sRNA biogenesis. Further, the cell wall component chitin was identified from Pb zoosporangia during the early infection and RNAi interfering with its biosynthesis in transgenic plants of Arabidopsis and Brassica napus blocked Pb early infection and conferred broad-spectrum resistance. Our study uncovers an unusual RNAi pathway in Rhizaria and provides a promising strategy to control cruciferous clubroot disease.

Plasmodiophora brassicae↗
PubMed2025

Inactivation of β-1,3-glucan synthase-like 5 confers broad-spectrum resistance to Plasmodiophora brassicae pathotypes in cruciferous plants.

Clubroot disease, caused by the obligate intracellular rhizarian protist Plasmodiophora brassicae, is devastating to cruciferous crops worldwide. Widespread field P. brassicae pathotypes frequently overcome the pathotype-specific resistance of modern varieties, posing a challenge for durable control of this disease. Here a genome-wide association study of 3 years of data comprising field clubroot phenotyping of 244 genome-resequenced Brassica napus accessions identified a strong association of β-1,3-glucan synthase-like 5 (GSL5) with clubroot susceptibility. GSL5 was evolutionarily conserved, and inactivation of GSL5 by genome editing in Arabidopsis, B. napus, Brassica rapa and Brassica oleracea conferred broad-spectrum, high-level resistance to P. brassicae pathotypes without yield penalties in B. napus. GSL5 inactivation derepressed the jasmonic acid-mediated immunity during P. brassicae secondary infection, and this immune repression was possibly reinforced through stabilization of GSL5 by a P. brassicae effector, facilitating clubroot susceptibility. Our study provides durable resistance resources for cruciferous clubroot disease control and insights into plant resistance against intracellular eukaryotic phytopathogens.

Disease Resistance↗
PubMed2006

Sequential priming and boosting with heterologous HIV immunogens predominantly stimulated T cell immunity against conserved epitopes.

BACKGROUND: The effort to develop an effective preventive vaccine against HIV-1 infection is challenged by the wide genetic diversity of HIV-1 among different isolates. OBJECTIVES: To explore a new vaccination strategy by using heterologous HIV immunogens derived from different clades for sequential priming and boosting. METHODS: HIV Env and Gag immunogens derived from Thailand B (B'), C/B' recombinant and A/E recombinant were selected as these three clades account for 29%, 45% and 15% of HIV-1 prevalence in China, respectively. Three humanized fusion genes of env and gag derived from those three clades were synthesized and inserted into DNA and recombinant Tiantan vaccinia vectors as model vaccines. C57BL/6 and Balb/c mice were used as animal model. Peptides spanning the entire Env and Gag were used as stimuli and Elispot assay was used to assess the T cell immunity. RESULTS: Sequential priming and boosting was observed with heterologous HIV immunogens predominantly stimulated T cell immunity against conserved epitopes, whereas a single vaccine derived from one clade or the mixture of multiple vaccines from different clades primarily raised T cells against less conservative or non-conservative epitopes. CONCLUSIONS: This is the first demonstration of a practical strategy to raise immune responses against conserved epitopes. This strategy has important implications for vaccine development against HIV and other pathogens that have high genetic diversity, such as influenza.

AIDS Vaccines↗
PubMed2006

The characterization of alpha5-integrin expression on tubular epithelium during renal injury.

The hallmark of progressive chronic kidney disease is the deposition of extracellular matrix proteins and tubulointerstitial fibrosis. Integrins mediate cell-extracellular matrix interaction and may play a role tubular epithelial injury. Murine primary tubular epithelial cells (TECs) express alpha(5)-integrin, a fibroblast marker and the natural receptor for fibronectin. Microscopy localized alpha(5)-integrin on E-cadherin-positive cells, confirming epithelial expression. The expression of alpha(5)-integrin increased in TECs grown on fibronectin and occurred in parallel with an upregulation of alpha-smooth muscle actin (alphaSMA), a marker of epithelial-mesenchymal transition (EMT). Exposure of TECs to transforming growth factor (TGF)-beta also increased TEC alpha(5)-integrin expression in association with alphaSMA and EMT. Knock-down of alpha5-integrin expression with short interfering RNA attenuated the TGF-beta induction of alphaSMA but did not alter morphologic EMT. Rather, alpha5-integrin was necessary for epithelial cell migration on fibronectin but not type IV collagen during cell spreading and epithelial wound healing in vitro. Immunohistochemistry revealed basolateral tubular epithelial alpha(5)-integrin expression in mouse kidneys after unilateral ureteric obstruction but not in contralateral control kidneys. In patient biopsies of nondiabetic kidney disease, alpha(5)-integrin expression was increased significantly in the renal interstitium. Focal basolateral staining was also detected in injured, but not in normal, tubular epithelium. In summary, these data show that TECs are induced to express alpha(5)-integrin during EMT and tubular epithelial injury in vitro and in vivo. These results increase our understanding of the biology of integrins during EMT and tubular injury in chronic kidney disease.

Animals↗
PubMed2006

[Preoperative hepatic and regional arterial infusion chemotherapy in the prevention of liver metastasis after colorectal cancer surgery].

OBJECTIVE: To investigate the effects of preoperative hepatic and regional arterial infusion chemotherapy (PHRAIC) in the prevention of liver metastasis of colorectal cancer after surgery. METHODS: 110 patients of colorectal cancer underwent perfusion of 3 anti-tumor drugs into the hepatic artery and nutrient artery of the tumor respectively, radical surgery of the colorectal cancer 7 days after, and then general venous chemotherapy 3 weeks after operation, 112 patients underwent radical surgery of the colorectal cancer and general venous chemotherapy 3 weeks after operation. Follow-up was carried out every month with a follow-up period of 34 months +/- 3 months. RESULTS: There were no significant difference in post-operational complications between these 2 groups. The 3-year liver metastasis rate, 3-year tumor-free survival rate, overall survival rate, and median survival time of the stage III patients in the PHRAIC group were 12.7%, 82.3%, 87.7%, and 40 months +/- 5 months, all significantly better than those in the control group (28.3%, 58.7%, 75.5%, and 36 months +/- 3 months respectively, P < 0.05 or P < 0.01). CONCLUSION: PHRAIC reduces the liver metastasis of colorectal cancer after radical surgery and improves the survival of the stage III patients.

Aged↗
PubMed2006

[Study on the comparison of polysaccharides in Ginkgo biloba leaves].

OBJECTIVE: To determine the suitable tree's age, tree's sex and gathering seasons for Ginkgo biloba leaves. METHODS: The twelve different polysaccharides were obtained by extracting and precipitating from Ginkgo biloba leaves and to see if there were differences among them. The concentration of Ginkgo biloba leaf polysaccharides with the highest gain ratio will be determined by HPLC. RESULT: The average gain ratio of Ginkgo biloba leaf polysaccharides was 4.29%, among them the gain ratio of 10-years old female Ginkgo biloba leaf collected in the last ten days of September was the highests, its polysaccharides concentration was 61.5% with RSD = 2.5% (n = 6). CONCLUSION: The gain ratios were different in different Ginkgo biloba leaves and the changing rules provide scientific basis for the GAP of medicinal plants.

Analysis of Variance↗
PubMed2005

Synthesis of monodisperse poly(chloromethylstyrene-co-divinylbenzene) beads and their application in separation of biopolymers.

The monodisperse, porous poly(chloromethylstyrene-co-divinylbenzene) beads of 7.9 microm were prepared by a single-step swelling and polymerization method. The seed particles prepared by dispersion polymerization exhibited good absorption of the monomer phase. Based on this media, a weak cation-exchange (WCX) stationary phase for HPLC was synthesized by a new chemically modified method. The prepared resin has advantages of biopolymer separation, high column efficiency, low column backpressure, high protein mass recovery, and good resolution for proteins. The dynamic protein-loading capacity of the synthesized WCX packings was 18.2 mg/g. Five proteins were separated in 3.0 min using the synthesized WCX stationary phase. The experimental results show that the obtained WCX resin has very weak hydrophobicity. The WCX resin was also used for the rapid separation and purification of lysozyme from egg white in 5.0 min with only one step. The purity and specific bioactivity of the purified lysozyme were found to be more than 93% and 70 245 U/mg, respectively.

Animals↗
PubMed2005

Soluble fibronectin induces chemokine gene expression in renal tubular epithelial cells.

BACKGROUND: Increasing proteinuria in kidney disease is associated with an increased risk of renal failure. Urinary proteins such as albumin induce inflammatory signaling and gene expression in tubular epithelial cells (TECs). Fibronectin is an extracellular matrix protein that can exist in soluble form and is excreted in the urine of patients with glomerular disease. METHODS: To explore the impact of soluble fibronectin on tubular epithelium, murine TECs were stimulated with soluble fibronectin and chemokine mRNA was determined by RNase protection assay. RESULTS: Fibronectin induced the expression of inflammatory chemokine genes, including monocyte chemoattractant protein-1 (MCP-1) (CCL2) and macrophage inflammatory protein-2 (MIP-2) within 2 hours in a dose-dependent manner. Phosphorylation of Src family tyrosine kinases was also increased in TECs following exposure to fibronectin. Src tyrosine kinases were involved in the fibronectin activation of MCP-1 since the Src inhibitors SU6656 and PP2 effectively reduced the induction of this chemokine. Fibronectin also induced the phosphorylation of extracellular signal-regulated protein kinase (ERK1/2) within minutes in TECs. The ERK kinase (MEK1/2) inhibitor U0126 inhibited the fibronectin induction of MCP-1 mRNA suggesting that ERK1/2 was also involved in this inflammatory pathway. Furthermore, fibronectin also induced phosphorylation of IkappaBalpha within 20 minutes in TECs. The nuclear factor-kappaB (NF-kappaB) inhibitors N-acetyl-L-cysteine (NAC) and pyrrolidinecarbodithioic acid (PDTC) effectively blocked fibronectin induction of MCP-1 mRNA. CONCLUSION: Soluble fibronectin activates MCP-1 gene expression in TECs via Src tyrosine kinases, ERK1/2 and NF-kappaB. These data provide further support to the concept that proteinuria per se contributes to the tubulointerstitial injury observed in glomerular disease.

Animals↗
PubMed2005

[A study on clinical differential diagnosis between hemangioma and vascular malformation in infant].

OBJECTIVE: To explore the main points of clinical differentiation between hemangioma and vascular malformation in infant. METHODS: Based on Mulliken and Waner's classification, from March, 1997 to February, 1999, 81 baby patients with hemangioma were included in this study. Thirty-eight cases, 43 cases received medical treatment of steroids. RESULTS: All the patients were followed up from 5 to 7 years. Thirty-eight cases of red strawberry-like lesions limited in the skin began to involute within two years old. Of the 30 patients with strawberry-like lesions and subcutaneous mass, 20 cases involuted in varying degree; 10 cases' subcutaneous mass grew gradually and didn't involute, in 4 cases biopsy was performed, 3 cases were confirmed as hemangioma accompanied with venous malformation by pathology, 1 case was hemangioma accompanied with arteriovenous malformation. Of 13 cases with light blue or normal skin and subcutaneous mass, 7 cases involuted in varying degree; 6 cases grow gradually and didn't disappear, 2 cases were confirmed as venous malformation by biopsy. CONCLUSIONS: Hemangioma in infant begins to involute within two years old. Vascular malformation or hemangioma with deep vascular malformation grows persistently and does not disappear. Skin temperature of lesion surface and dilative veins on the skin artery pulsation, are indexes compressibility, for differentiation between hemangioma and vascular malformation in clinical diagnosis.

Child, Preschool↗
PubMed2005

[Determination of molecular weight and content of Ginkgo biloba exocarp polysaccharides by HPLC].

OBJECTIVE: To determine the molecular weight and content of Ginkgo biloba exocarp polysaccharides. METHOD: The analysis was carried on a PL aquagel-OH MIXED (7.5 mm x 300 mm, 8 microm) chromatography column eluted with water as mobile phase at 1.0 mL x min(-1) of flow rate, the column temperature was 25 degrees C and the eluate was detected by RID. RESULT: The average molecular weight of Ginkgo bilobaexocarp polysaccharides was 11 062.5 with RSD = 0.78% (n = 6); the content was 81.9% with RSD = 2.5% (n = 6), the standard curves of dextran (MW 12 000) were linear in the range of 1-20 microg, r = 0.999 9. The average recovery is 97.9%, RSD was 2.5%. CONCLUSION: This method was found to be sensitive and accurate for the measurement of Ginkgo biloba exocarp polysaccharides.

Chromatography, High Pressure Liquid↗
PubMed2004

[Genetic relationships among five populations of Oxya chinensis in Shanxi Province and adjacent region based on RAPD].

Random Amplified Polymorphic DNA (RAPD) markers were applied to analyze genetic relationships of five populations of Oxya chinensis collected from Shanxi Province and laner Mongolia, Oxya japonica from Guangxi was used as an outgroup. Genomic DNA of sixty-four individuals was extracted from dissected leg muscle using phenol-chloroform procedure, and then amplified by 10 random primers (10 bp), the amplified products were separated by agarose gel electrophoresis. The results were as follows: (1) a total of 115 clear and reproducible bands were generated, molecular size was 200 - 2500 bp. The obtaining segments of individual primer were among 5 - 15, on average, about 12 bands per primer. (2) The dendrogram based on 115 RAPD markers was constructed and clustered using between-groups linkage method. The cluster analysis indicated strong similarities within populations, firstly, the individuals in each population closely clustered together;and then five populations of Oxya chinensis could be distinguished with RAPD markers and were grouped into two distinct clusters. The dendrogram showed that Shanxi Linyi population and Tunliu population were the most similar,which were clustered with Taiyuan population Shanxi into one cluster, while, Daixian population in Shanxi was closely related to laner Mongolia population, both of which belonged to the other cluster. Nevertheless, All the five populations of Oxya chinensis had far genetic distance with Oxya japonica. In the dendrogram, a tendency of clustering following a North-South gradient could be observed, the results implied that genetic distance of five populations of Oxya chinensis correlated with geographical distance to some degree.

Animals↗
PubMed2004

[Tumor necrosis factor alpha and myocardial matrix metalloproteinases in left ventricular remodeling].

OBJECTIVE: The cytokine tumor necrosis factor (TNF) alpha has been causally linked to left ventricular (LV) remodeling, but the molecular basis for this effect is unknown. It is essential to study the changes of plasma levels of TNF alpha and matrix metalloproteinase-2,3,9 (MMP-2,3,9) expressions in myocardium during congestive heart failure (CHF). METHODS: Plasma levels of TNF alpha were measured with enzyme-linked immunoassay in CHF patients of various degrees and in healthy controls. Using Western blotting assay, we detected the protein expressions of MMP-2,3,9 on myocardial tissue in CHF patients and in healthy controls. Cardiac function parameters were measured with echocardiographic studies. RESULTS: Plasma levels of TNF alpha increased significantly in patients with CHF (P < 0.05 or < 0.01). The protein expressions of MMP-2,3,9 were significantly higher in patients with CHF than in controls (P < 0.05 or < 0.01). The higher the degree of CHF, the greater the numbers of expressions. No changes of MMP-2 could be found between the controls and CHF patients of NYHA II. There was a positive correlation between plasma levels of TNF alpha and the protein expressions of MMP-2,3,9 (P < 0.01 or < 0.001). CONCLUSIONS: It is suggested that alterations of TNF alpha may stimulate the expressions of MMPs, contribute to myocardial remodeling and lead to the development and progression of congestive heart failure. These changes may induce a direct effect on the progression and deterioration of heart failure.

Adult↗
PubMed2004

[Myocardial ultrastructural changes in rats following different levels of acute +Gz exposure].

OBJECTIVE: To observe the effects of different levels of acute +Gz exposure on myocardial ultrastructure of rats and provide experimental basis for further development of anti-G measures. METHOD: Twenty male Wistar rats were randomly divided into 4 groups (n=5): normal control group, +20 Gz group, +10 Gz group and +5 Gz group. Profile of the centrifuge +Gz exposure was trapezoidal, in which +20 Gz lasted for 30 s, +10 Gz for 1.5 min. +5 Gz exposure was repeated for 3 times with 30 min interval and each for 1.5 min. Myocardial tissue of left ventricle was sampled for transmission electron microscopy 5 h after exposure. RESULT: +20 Gz and +10 Gz exposure caused obvious edema of myocardial and endothelial cells, myofibril disorder and injuries of mitochondria and nucleus. Breaks of myocardial fiber, formation of contraction bands and rupture of mitochondria were also observed in +20 Gz group. In +5 Gz group, there was still slight edema of myocardial and endothelial cells, while organic changes of myocardial ultrastructure were not observed. CONCLUSION: High +Gz exposure can cause myocardial ultrastructural injury in rats. Slight reversible injured response can also be observed in myocardial cell after repeated moderate level of +Gz exposure. This indicates that attention should be paid to the study of the effect of high +Gz on heart in pilots.

Acceleration↗
PubMed2003

Lattice Boltzmann model for agrochemical transport in soils.

Agrochemical transport in soils is complicated and involves physical, chemical and biochemical reactions; its mathematical modelling remains a challenging task. This paper presents a lattice Boltzmann model to simulate the agrochemical movement. The lattice Boltzmann model is a microscopic and process-based model, simulating the transport process by tracking chemical particles. The model presented in this paper is for one-dimensional vertical leaching and assumes that the chemical particles at the microscopic level move in five directions: one stagnant, two in vertical direction and two in an internal horizontal direction bounded by two reactive walls. Reactions at the walls are assumed to take place at two different rates, one in fast rate where the chemicals in the solution and on the wall are in an instant equilibrium, and the other in slow rate where the mass exchange rate between the chemicals in the solution and on the wall is a first-order kinetic. The reactions on both walls are assumed to occur instantly when the chemical particles moving in the internal direction hit the walls. To test the model, we measured the leaching of atrazine through soil columns in the laboratory. The results simulated with the lattice Boltzmann model are compared with the measured breakthrough curves and the non-equilibrium two-site convection-dispersion model; they all show close agreement. The transport parameters needed in the models are obtained from the measurement of adsorption isotherm of atrazine, bromide leaching in the same soil columns and calibration.

Agriculture↗
PubMed2002

Directing abilities of alcohol-derived functional groups in the hydroformylation of olefins.

The hydroformylation of allylic and homoallylic alcohols and their derivatives using cationic and neutral rhodium complexes has been examined. The highest diastereoselectivity (87:13) was observed in the reaction of 1-methoxymethoxy-2-methylenecyclohexane. Higher yields and similar selectivities were obtained in the reaction of the TBDMS-protected alcohol. The major diastereomer results from hydroformylation syn to the functional group, which would suggest a directing effect. However, hydroformylation of 3-methylene-1-cyclohexanol derivatives occurs on the face opposite to the directing group in the major isomer. These data, in addition to the results of hydroformylation of 1-methyl-2-methylenecyclohexane, suggest that inherent conformational preferences are of significant importance in determining the product distribution and that the directing power of simple alcohols and their derivatives is moderate at best under the conditions examined in this study.

Journal Article↗
PubMed2002

[Gene expression of Ang II receptors in myocardium in congestive heart failure].

OBJECTIVE: To explore the relation among myocardial AT(1)-/AT(2)- receptor expression, myocardial remodeling and cardiac function in patients with congestive heart failure. METHODS: Pathologic and morphologic studies on myocardial tissue of 31 patients with CHF due to valvular heart disease and 5 control subjects were carried out with optical and electronic microscopy. Message RNA expression of and AT(1)-/AT(2)-receptors in myocardial tissue were analyzed using the reverse transcriptase-polymerase chain reaction. RESULTS: Pathological changes of myocardial tissue in CHF due to valvular heart disease showed typical myocardial remodeling. AT(1)-receptor mRNA expression was slightly increased in the patients with mild CHF than in the control subjects, but decreased in the moderate and severe CHF patients. No difference was observed in AT(2)-receptor mRNA expression among all the groups. CONCLUSIONS: The expression of AT(1)-receptor was up-regulated in mild CHF. Cardiomyocyte hypertrophy may be mediated by AT(1)-receptor. The expression of AT(1)-receptor was down-regulated in moderate and severe CHF. The do minant receptor subtype was transformed to AT(2). The significance of these alterations may be a local protective mechanism of myocardium. Cardiomyocyte apoptosis may be induced via AT(2)-receptor, leading to deterioration of cardiac function.

Adult↗
PubMedDate not supplied

Simulating nonequilibrium transport of atrazine through saturated soil.

Atrazine, an herbicide widely used for selective control of grassy weeds in the fields where maize is grown, is a potential ground water contaminant in China and, consequently, there is interest in predicting its mobility in agricultural soils. In this study, we determined the nonequilibrium transport characteristics of atrazine in Shahe soil (Beijing sandy loam) using the advection-dispersion equation, and using a sensitivity analysis, we evaluated the contribution of the uncertainty in a given input parameter to the overall uncertainty in model results. The asymmetrical shape and tailing of the atrazine breakthrough curve (BTC) showed that atrazine was subject to nonequilibrium transport. The observed atrazine BTC was best fitted by the chemical nonequilibrium model with a nonlinear least-squares optimization approach. Results from the sensitivity analysis indicated that the retardation factor was the most sensitive parameter. Considering the reliability of the estimated parameters, the best fit to the atrazine BTC was obtained by fixing the retardation factor based on the linear distribution coefficient, and by calculating the dispersion coefficient from the bromide BTC and the average pore water velocity from the measured data; nonequilibrium parameters were the only unknown parameters that were optimized. Model verification procedures were based on best-fit parameters optimized from one soil column experiment and applied to simulate the transport of atrazine in the duplicate experiment. The results showed there was good agreement between measured and simulated concentrations for atrazine leaching in the soil column.

Atrazine↗