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991.
OsTDL1A binds to the LRR domain of rice receptor kinase MSP1, and is required to limit sporocyte numbers 总被引:1,自引:0,他引:1
Zhao X de Palma J Oane R Gamuyao R Luo M Chaudhury A Hervé P Xue Q Bennett J 《The Plant journal : for cell and molecular biology》2008,54(3):375-387
Hybrids lose heterotic yield advantage when multiplied sexually via meiosis. A potential alternative breeding system for hybrids is apospory, where female gametes develop without meiosis. Common among grasses, apospory begins in the nucellus, where aposporous initials (AIs) appear near the sexual megaspore mother cell (MeMC). The cellular origin of AIs is obscure, but one possibility, suggested by the mac1 and msp1 mutants of maize and rice, is that AIs are apomeiotic derivatives of the additional MeMCs that appear when genetic control over sporocyte numbers is relaxed. MULTIPLE SPOROCYTES1 (MSP1) encodes a leucine-rich-repeat receptor kinase, which is orthologous to EXS/EMS1 in Arabidopsis. Like mac1 and msp1, exs/ems1 mutants produce extra sporocytes in the anther instead of a tapetum, causing male sterility. This phenotype is copied in mutants of TAPETUM DETERMINANT1 (TPD1), which encodes a small protein hypothesized to be an extracellular ligand of EXS/EMS1. Here we show that rice contains two TPD1-like genes, OsTDL1A and OsTDL1B. Both are co-expressed with MSP1 in anthers during meiosis, but only OsTDL1A and MSP1 are co-expressed in the ovule. OsTDL1A binds to the leucine-rich-repeat domain of MSP1 in yeast two-hybrid assays and bimolecular fluorescence complementation in onion cells; OsTDL1B lacks this capacity. When driven by the maize Ubiquitin1 promoter, RNA interference against OsTDL1A phenocopies msp1 in the ovule but not in the anther. Thus, RNAi produces multiple MeMCs without causing male sterility. We conclude that OsTDL1A binds MSP1 in order to limit sporocyte numbers. OsTDL1A-RNAi lines may be suitable starting points for achieving synthetic apospory in rice. 相似文献
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994.
Han HJ Tan NH Zeng GZ Fan JT Huang HQ Ji CJ Jia RR Zhao QS Zhang YJ Hao XJ Wang LQ 《化学与生物多样性》2008,5(7):1364-1368
DNA Topoisomerase I can cause DNA breaks and play a key role during cell proliferation and differentiation. It is an important target for anticancer agents. While screening for anticancer compounds, seven natural compounds, 1-7, showed potent cytotoxicities against a panel of ten cancer cell lines. Moreover, an inhibition assay demonstrated that they are also DNA topoisomerase I inhibitors, in which inhibitors 1-5 are new ones. 相似文献
995.
Zhao C Qi J Liu X Chen H Li J Liu Y Liang L Zhang Y Xiao J Li L Peng L Xu J Ma J Yang Y Wu X Chen YH 《Experimental biology and medicine (Maywood, N.J.)》2008,233(11):1441-1447
The cardiomyocytes in the superior vena cava (SVC) myocardial sleeve have distinct action potentials and ionic current profiles, but the refractoriness of these cells has not been reported. Using standard intracellular microelectrode techniques, we demonstrated in sheep that the effective refractory period (ERP) of the cardiomyocytes in the SVC (114.7 +/- 6.5 ms) is shorter than that in the inferior vena cava (IVC) (166.7 +/- 6.2 ms), right atrial free wall (RAFW) (201.0 +/- 6.0 ms) and right atrial appendage (RAA) (203.1 +/- 5.8 ms) (P < 0.05). The right atrial cardiomyocyte ERP was heterogeneously shortened by acetylcholine, a muscarinic type 2 receptor (M(2)R) agonist. After perfusion with 15 microM acetylcholine, the shortest ERP occurred in the SVC (the ERP in the SVC, IVC, RAFW and RAA was 53.6 +/- 2.7, 98.9 +/- 2.2, 121.8 +/- 6.0 and 109.7 +/- 5.1 ms, respectively; P < 0.05). Carbachol (1 microM), another M(2)R agonist, produced a similar effect as acetylcholine. Furthermore, we used methoctramine, a M(2)R blocker, 4-DAMP, a muscarinic type 3 receptor (M(3)R) blocker, and tropicamide, a muscarinic type 4 receptor (M(4)R) blocker to inhibit the acetylcholine-induced ERP shortening of SVC cardiomyocytes, and found that the 50% inhibitory concentration for methoctramine, 4-DAMP and tropicamide was 5.91, 45.72 and 80.34 nM, respectively. Therefore, we conclude that the sheep SVC myocardial sleeve is a unique electrophysiological region of the right atrium with the shortest ERP both under physiological condition and under cholinergic agonist stimulation. M(2)R might play a major role in the response of the SVC myocardial sleeve to parasympathetic nerve tone. The association between the distinct refractoriness in SVC and atrial fibrillation originating from the region deserves further investigation. 相似文献
996.
Kong WN Zhao SE Duan XL Yang Z Qian ZM Chang YZ 《Journal of cellular biochemistry》2008,104(2):629-641
Recycled iron from reticuloendothelial macrophages to erythroid precursors is important to maintain the iron homeostasis. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. In this study, male Sprague-Dawley rats were treated with recombinant human erythropoietin (rHuEpo, 500 IU/day, s.c.) for 3 days. At the fifth day, peritoneal exudate macrophages were harvested, and then (55)Fe uptake and release were measured by liquid scintillation counting method. The expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in peritoneal exudate macrophages was detected by RT-PCR and Western blot. In order to exclude the direct effect of rHuEpo on macrophages, the parallel experiments were performed with incubation normal peritoneal exudate macrophages with rHuEpo (2 IU/ml). Our results showed rHuEpo injection reduced the peritoneal exudate macrophages iron retention. The uptake of Fe(II) was decreased via the suppression of DMT1 (+IRE) expression and the release of Fe(II) was increased with increasing the expression of FPN1 in macrophages. Moreover, the expression of HAMP mRNA was four times lower in rHuEpo-treated liver of rats than control group (CG). HAMP mRNA expression was increased; the synthesis of DMT1 had no significant change, whereas the FPN1 was decreased in normal peritoneal exudate macrophages after treatment with rHuEpo in vitro. We conclude that hepcidin may play a major, causative role in the change of FPN1 synthesis and that decreased the iron retention in macrophages of rHuEpo-treated rats. 相似文献
997.
The efficient conversion of lignocellulosic materials into fuel ethanol has become a research priority in producing affordable and renewable energy. The pretreatment of lignocelluloses is known to be key to the fast enzymatic hydrolysis of cellulose. Recently, certain ionic liquids (ILs) were found capable of dissolving more than 10wt% cellulose. Preliminary investigations [Dadi, A.P., Varanasi, S., Schall, C.A., 2006. Enhancement of cellulose saccharification kinetics using an ionic liquid pretreatment step. Biotechnol. Bioeng. 95, 904-910; Liu, L., Chen, H., 2006. Enzymatic hydrolysis of cellulose materials treated with ionic liquid [BMIM]Cl. Chin. Sci. Bull. 51, 2432-2436; Dadi, A.P., Schall, C.A., Varanasi, S., 2007. Mitigation of cellulose recalcitrance to enzymatic hydrolysis by ionic liquid pretreatment. Appl. Biochem. Biotechnol. 137-140, 407-421] suggest that celluloses regenerated from IL solutions are subject to faster saccharification than untreated substrates. These encouraging results offer the possibility of using ILs as alternative and non-volatile solvents for cellulose pretreatment. However, these studies are limited to two chloride-based ILs: (a) 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), which is a corrosive, toxic and extremely hygroscopic solid (m.p. approximately 70 degrees C), and (b) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl), which is viscous and has a reactive side-chain. Therefore, more in-depth research involving other ILs is much needed to explore this promising pretreatment route. For this reason, we studied a number of chloride- and acetate-based ILs for cellulose regeneration, including several ILs newly developed in our laboratory. This will enable us to select inexpensive, efficient and environmentally benign solvents for processing cellulosic biomass. Our data confirm that all regenerated celluloses are less crystalline (58-75% lower) and more accessible to cellulase (>2 times) than untreated substrates. As a result, regenerated Avicel((R)) cellulose, filter paper and cotton were hydrolyzed 2-10 times faster than the respective untreated celluloses. A complete hydrolysis of Avicel((R)) cellulose could be achieved in 6h given the Trichoderma reesei cellulase/substrate ratio (w/w) of 3:20 at 50 degrees C. In addition, we observed that cellulase is more thermally stable (up to 60 degrees C) in the presence of regenerated cellulose. Furthermore, our systematic studies suggest that the presence of various ILs during the hydrolysis induced different degrees of cellulase inactivation. Therefore, a thorough removal of IL residues after cellulose regeneration is highly recommended, and a systematic investigation on this subject is much needed. 相似文献
998.
Aims: To study fuel ethanol fermentation with Kluyveromyces marxianus ATCC8554 from Jerusalem artichoke (Helianthus tuberosus) grown in salina and irrigated with a mixture of seawater and freshwater. Methods and Results: The growth and ethanol fermentation of K. marxianus ATCC8554 were studied using inulin as substrate. The activity of inulinase, which attributes to the hydrolysis of inulin, the main carbohydrate in Jerusalem artichoke, was monitored. The optimum temperatures were 38°C for growth and inulinase production, and 35°C for ethanol fermentation. Aeration was not necessary for ethanol fermentation with the K. marxianus from inulin. Then, the fresh Jerusalem artichoke tubers grown in salina and irrigated with 25% and 50% seawater were further examined for ethanol fermentation with the K. marxianus, and a higher ethanol yield was achieved for the Jerusalem artichoke tuber irrigated with 25% seawater. Furthermore, the dry meal of the Jerusalem artichoke tubers irrigated with 25% seawater was examined for ethanol fermentation at three solid concentrations of 200, 225 and 250 g l?1, and the highest ethanol yield of 0·467, or 91·5% of the theoretical value of 0·511, was achieved for the slurry with a solid concentration of 200 g l?1. Conclusions: Halophilic Jerusalem artichoke can be used for fuel ethanol production. Significance and Impact of the Study: Halophilic Jerusalem artichoke, not competing with grain crops for arable land, is a sustainable feedstock for fuel ethanol production. 相似文献
999.
为了确定γ-氨基丁酸B受体(gamma-aminobutyric acid B receptor,GABABR)基因在异育银鲫(Carassius auratus gibelio)不同组织中的表达,本实验分别对异育银鲫不同组织中GABABR1基因进行RT-PCR扩增,并进行了克隆和测序,在与GenBank基因库中已知GABABR1序列进行同源性比对的基础上采用邻接法构建系统发育树,并进一步分析其在异育银鲫不同组织内的表达水平。结果:经克隆获得异育银鲫GABABR1基因CDS区序列383bp,编码127个氨基酸。荧光定量PCR结果显示GABABR1基因在异育银鲫脑、肝、肾、心、肠、鳔、鳃、肌、鳍、脾、卵巢、精巢组织中均有表达,且在不同组织中的表达水平由高到低依次是:脑>尾鳍>精巢>心、肠、鳔> 卵巢、脾、鳃、肌>肝、肾。本研究证实了GABABR1基因在异育银鲫各组织中的表达的广泛性,且有明显的组织特异性。 相似文献
1000.
Kai Zhao Wei Li Tingting Huang Xiaomei Luo Gang Chen Yang Zhang Chen Guo Chunxiao Dai Zheng Jin Yan Zhao Hongyu Cui Yunfeng Wang 《PloS one》2013,8(12)