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Geminiviruses encode a few proteins and depend on cellular factors to complete their replicative cycle. As a way to understand geminivirus-host interactions, we have searched for cellular proteins which interact with viral proteins. By using the yeast two-hybrid technology and the wheat dwarf geminivirus (WDV) RepA protein as a bait, we have isolated a family of proteins which we termed GRAB (for Geminivirus Rep A-binding). We report here the molecular characterization of two members, GRAB1 and GRAB2. We have found that the 37 C-terminal amino acids of RepA are required for interaction with GRAB proteins. This region contains residues conserved in an equivalent region of the RepA proteins encoded by other viruses of the WDV subgroup. The N-terminal domain of GRAB proteins is necessary and sufficient to interact with WDV RepA. GRAB proteins contain an unique acidic C-terminal domain while their N-terminal domain, of ca. 170 amino acids, are highly conserved in all of them. Interestingly, this conserved N-terminal domain of GRAB proteins exhibits a significant amino acid homology to the NAC domain present in proteins involved in plant development and senescence. GRAB1 and GRAB2 mRNAs are present in cultured cells and roots but are barely detectable in leaves. GRAB expression inhibits WDV DNA replication in cultured wheat cells. Our studies highlight the importance that the pathway(s) mediated by GRAB proteins, as well as by other NAC domain-containing proteins, might have on geminivirus DNA replication in connection to plant growth, development and senescence pathways.  相似文献
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乳杆菌微胶囊化培养的研究   总被引:11,自引:0,他引:11       下载免费PDF全文
采用MaCSPDMDAAC微胶囊对两种乳杆菌进行了固定化发酵研究。结果表明,两种乳杆菌能够在微胶囊内很好地生长和繁殖,菌浓度可分别达到18×1011/mL 胶囊和269×1011/mL胶囊,比游离培养高出十倍以上,并且能与游离发酵一样产生乳酸,糖耗时间可缩短1/3~2/3。进行的多批次发酵显示了巨大的产酸能力。  相似文献
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企鹅珍珠贝彩虹珠的研究初报   总被引:11,自引:0,他引:11       下载免费PDF全文
毛勇  梁飞龙  符韶  余祥勇  叶富良  邓陈茂 《动物学杂志》2004,39(1):100-102,F002
利用企鹅珍珠贝培育出了不同颜色的天然彩色珍珠,俗称“彩虹珠”,并对其形状及颜色进行了描述。“彩虹珠”颜色的形成与企鹅珍珠贝贝壳珍珠层的本身色泽及插核小片的位置有关,其珍珠质的分泌速度也较快,经3个月育珠,珠层厚度可达300μm以上,经9个月育珠可达890μm。但由于插核部位狭小,现有的技术水平还不能生产大型珍珠。  相似文献
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Mechanisms and strategies to overcome multiple drug resistance in cancer   总被引:10,自引:0,他引:10  
Ozben T 《FEBS letters》2006,580(12):2903-2909
One of the major problems in chemotherapy is multidrug resistance (MDR) against anticancer drugs. ATP-binding cassette (ABC) transporters are a family of proteins that mediate MDR via ATP-dependent drug efflux pumps. Many MDR inhibitors have been identified, but none of them have been proven clinically useful without side effects. Efforts continue to discover not toxic MDR inhibitors which lack pharmacokinetic interactions with anticancer drugs. Novel approaches have also been designed to inhibit or circumvent MDR. In this review, the structure and function of ABC transporters and development of MDR inhibitors are described briefly including various approaches to suppress MDR mechanisms.  相似文献
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In higher plants, although several genes involved in shoot apical meristem (SAM) formation and organ separation have been isolated, the molecular mechanisms by which they function are largely unknown. CUP-SHAPED COTYLEDON (CUC) 1 and CUC2 are examples of two such genes that encode the NAC domain proteins. This study investigated the molecular basis for their activities. Nuclear localization assays indicated that green fluorescent protein (GFP)-CUC proteins accumulate in the nucleus. Yeast one-hybrid and transient expression assays demonstrated that the C-terminal domain (CTD) of the CUC has transactivation activity. Domain-swapping experiments revealed that the functional specificity of the CUC for promoting adventitious shoot formation resides in the highly conserved NAC domain, not in the CTD in which motifs specific to the CUC subfamily are located. Taken together, these observations suggest that CUC proteins transactivate the target genes involved in SAM formation and organ separation through a specific interaction between the NAC domain and the promoter region of the target genes.  相似文献
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微胶囊固定化酵母培养的研究   总被引:7,自引:0,他引:7  
进行了NaCSPDMDAAC微胶囊固定化酒精酵母和产朊假丝酵母的实验研究。考察了这两种酵母的培养规律,发现微胶囊固定化酒精酵母的产酒精情况与游离培养基本一致,在连续发酵16批后,仍具有良好的性能。同时固定化产谷胱甘肽(GSH)的产朊假丝酵母的研究也表明固定化培养GSH产量与游离细胞产量相近  相似文献
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