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The micronutrient content of most cereal grains is low and responsible for malnutrition deficiencies in millions of people who rely on grains as their primary food source. Any strategy that can increase the micronutrient content of grain will have significant benefits to world health. We identified a gene from barley encoding a cell wall protein with multiple histidine (His)-rich motifs interspersed with short arabinogalactan-protein (AGP) domains and have called it Hordeum vulgare His-rich AGP (HvHRA1). Sequence analysis shows that His-rich AGPs are rare in plants and that the number of His-rich and AGP domains differ between cereals and dicots. The barley and wheat encoded proteins have more than 13 His-rich domains, whereas the putative rice orthologue has only 5 His-rich regions. His-rich motifs are well-established metal-binding motifs; therefore, we developed transgenic (Tx) rice plants that constitutively overexpress barley HvHRA1. There was no significant effect on plant growth or grain yield in Tx plants. Purification of AGPs from wild-type and Tx plants showed that only Tx plants contained detectable levels of a His-rich AGP. Calcein assay shows that the AGP fraction from Tx plants had increased binding affinity for Cu(2+) . Micronutrient analysis of brown and white rice showed that the grain nutrient yield for Fe, Zn and Cu was higher in two Tx lines compared to their respective nulls, although the differences were not statistically significant. This approach highlights the potential of the plant apoplast (cell wall) for storage of key nutrients through overexpression of genes for metal-binding proteins. 相似文献
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为了探讨叶绿体类囊体膜抗坏血酸过氧化物酶(tAPX)与其抗氧化性的关系,从番茄叶片中分离了叶绿体类囊体膜抗坏血酸过氧化物酶基因(StA跚并转入到烟草中。以野生型(WT)、转正义StAPX烟草株系T3-3和T3-6为试材,测定了外源过氧化氢诱导的氧化胁迫条件下APX酶活性、过氧化氢酶(CAT)活性、过氧化氢(H2O2)含量、叶绿素荧光参数及叶绿素含量等。Northern杂交显示StAPX因的表达受外源H2O2氧化胁迫的诱导。氧化胁迫下转基因烟草的APX酶活性和清除H2O2的能力都显著高于野生型,并且转基因烟草比野生型具有更高的PSII最大光化学效率及叶绿素含量。结果表明,.刚尸舶勺过量表达有助于提高外源H2O2诱导的转基因烟草的抗氧化能力。 相似文献
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References: 《生物数学学报》1998,13(4):435-438
IIntroductionIn1993,KuangY[11gavetheopenp毗fern9.2:恤tainsufficientCOnditionsfortheeds-tenceofpO8ltlvependIc劝utionsinN”(t)=N(t)[a(t)一B(t)N()一b(t)N(t—r(t))-c(t)N”(t一巾》】(1)wherea(t),尸(t),b(t),c(t),,(t)are。"negativecontinuouspo。odlcfunctionswithpenodT.Inthispaper,weconsideraspecialcasewheng(t)。0,b(t)>0,c(t)。c,r(t)。,,i.e.O鹏idertheexlstenceOfp用tlvependicdutionsOftkforirlBynsf叩ofsomenewtechnicsandtoPOloglcaldeg… 相似文献
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The phenylpropanoid pathway yields a variety of phenolics that are closely associated with fruit qualities in addition to structural and defense-related functions. However, very little has been reported concerning its metabolism in fruit. This experiment was designed to assess changes of eleven phenolic acids in grape berry (Vitis vinifera L. cv. Cabernet Sauvignon) and explore both the activities and amounts of three key enzymes--phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate:coenzyme A ligase (4CL)--catalyzing the biosynthesis of these compounds during berry development. Finally, the subcellular localizations of the enzymes within berry tissues were also investigated using immuno-gold electron microscopic technique. The results indicated that the contents of gallic, protocatechuic, gentisic and caffeic acid all changed drastically during berry development, while other compounds containing p-hydroxybenzoic, vanillic, syringic, chlorogenic, p-coumaric, ferulic and sinapic acid varied only slightly. Activities of PAL, C4H and 4CL showed similar pattern changes with two accumulated peaks throughout berry development. In addition, their activities all showed a highly positive correlation with the total contents of phenolic acids, whereas the immunoblotting analysis showed that changes in enzyme activities were independent of the enzyme amounts. Results from the subcellular-localization study revealed that PAL was mainly present in the cell walls, secondarily thickened walls, and the parenchyma cells of the berry mesocarp cells, C4H was found primarily in the chloroplast (plastid) and nucleus and 4CL predominantly in the secondarily thickened walls and the parenchyma cells of mesocarp vascular tissue. 相似文献
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Smad4, originally isolated from the human chromosome 18q21, is a key factor in transducing the signals of the TGF-β superfamily of growth hormones and plays a pivotal role in mediating antimitogenic and proapoptotic effects of TGF-β, but the mechanisms by which Smad4 induces apoptosis are elusive. Here we report that Smad4 directly translocates to the mitochondria of apoptotic cells. Smad4 gene silencing by siRNA inhibits TGF-β-induced apoptosis in Hep3B cells and UV-induced apoptosis in PANC-1 cells. Cell fractionation assays demonstrated that a fraction of Smad4 translocates to mitochondria after long time TGF-β treatment or UV exposure, during which the cells were under apoptosis. Smad4 mitochondria translocation during apoptosis was also confirmed by fluorescence observation of Smad4 colocalization with MitoTracker Red. We searched for mitochondria proteins that have physical interactions with Smad4 using yeast two-hybrid screening approach. DNA sequence analysis identified 34 positive clones, five of which encoded subunits in mitochondria complex IV, i.e., one clone encoded cytochrome c oxidase COXII, three clones encoded COXIII and one clone encoded COXVb. Strong interaction between Smad4 with COXII, an important apoptosis regulator, was verified in yeast by β-gal activity assays and in mammalian cells by immunoprecipitation assays. Further, mitochondrial portion of cells was isolated and the interaction between COXII and Smad4 in mitochondria upon TGF-β treatment or UV exposure was confirmed. Importantly, targeting Smad4 to mitochondria using import leader fusions enhanced TGF-β-induced apoptosis. Collectively, the results suggest that Smad4 promote apoptosis of the cells through its mitochondrial translocation and association with mitochondria protein COXII. 相似文献
60.
T-DNA突变体是研究基因功能的重要资源。高效热不对称交错PCR (hiTAIL-PCR)是克隆突变体中T-DNA插入位点侧翼序列的常用方法。然而我们发现, 利用hiTAIL-PCR克隆到的一些侧翼序列并不对应于宿主的染色体DNA序列, 而是质粒的骨架DNA片段。通过设置1组RB-S4/AC1或者LB-A4/AC1对照反应, 用PCR方法鉴定了hiTAIL-PCR扩增产物中位于T-DNA侧翼的质粒骨架片段。在后续分析中, 通过排除这些片段, 提高了利用hiTAIL-PCR获得宿主染色体DNA片段的效率。同时, 通过调整反应程序, 使得整个PCR的反应时间也大为缩短。在拟南芥(Arabidopsis thaliana) T-DNA突变体drf1侧翼序列的克隆实例中, 对照反应的引入将hiTAIL-PCR中需鉴定的22条扩增产物降至4条, 效率提高了81.8%。 相似文献