991 resultados para 355.030861 S211s


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Understanding the regulatory mechanisms that are responsible for an organism's response to environmental change is an important issue in molecular biology. A first and important step towards this goal is to detect genes whose expression levels are affected by altered external conditions. A range of methods to test for differential gene expression, both in static as well as in time-course experiments, have been proposed. While these tests answer the question whether a gene is differentially expressed, they do not explicitly address the question when a gene is differentially expressed, although this information may provide insights into the course and causal structure of regulatory programs. In this article, we propose a two-sample test for identifying intervals of differential gene expression in microarray time series. Our approach is based on Gaussian process regression, can deal with arbitrary numbers of replicates, and is robust with respect to outliers. We apply our algorithm to study the response of Arabidopsis thaliana genes to an infection by a fungal pathogen using a microarray time series dataset covering 30,336 gene probes at 24 observed time points. In classification experiments, our test compares favorably with existing methods and provides additional insights into time-dependent differential expression.

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植物血红蛋白在共生固氮根瘤中主要是对固氮酶进行嫌氧保护,确保固氮酶活性,在植物根中协助氧的运输或作为感觉氧压的信号分子.豆科植物凝集素功能之一是对相应专一的根瘤菌有识别作用,并有利于根瘤菌的聚集和侵染。本论文将非豆科结瘤植物Parasponia andersonii血红蛋白基因及豌豆凝集索基因转入水稻,目的是此二基因表达后,豌豆凝集素可聚集、识别豌豆根瘤菌,并有助于它们的侵染,血红蛋白则可对根瘤菌固氮酶进行嫌氧保护,保障其发挥固氮作用,从而为实现水稻结瘤和固氮打下初步基础。 本论文将带有Parasponia血红蛋白基因的pL305质粒,带有潮霉素磷酸转移酶基因及Parasponia血红蛋白基因的农杆菌双元载体质粒pLX412-Hb用花粉管通道法转化水稻l用pLX412-Hb和带有Bar基因、豌豆凝集素基因、Parasponia血红蛋白基因的质粒pLHB用基因枪法转化水稻幼胚及愈伤组织,带有pLX412-Hb的Agrobactmum tumefaciens LBA4404转化烟草,得到如下结果: 1.用pL305质粒花粉管通道法转化水稻,运作1512朵花,得到707粒种子.将230粒种子萌发,发芽220粒;白化苗4株,成苗206株;计发芽率96%,白化苗率1.7%,成苗率90%。取120株提取DNA以Parasponia血红蛋白基因为探针进行点杂交,有6株为阳性结果,阳性率5%.再取4株DNA点杂交阳性植株DNA,以Parasponia血红蛋白基因为探针进行Southem杂交,有3株有阳性结果,阳性率为75%,照此推算转化植株约占总植株的4%.目前,这些转基因植株已开花结实。 2.用pLX412-Hb质粒花粉管通道法转化水稻,运作743朵花,得到340粒种子。将120粒种子萌发,发芽117粒,白化苗3株,成苗111株;计发芽率97. 5%,白化苗率2. 5%,成苗率92. 5%.取30株提取DNA以Parasponia血红蛋白基因为探针进行点杂交,有4株为阳性结果,阳性率13%。再取4株DNA点杂交呈阳性的植株DNA,以Parasponia血红蛋白基因为探针进行Southern杂交,有2株有阳性结果,阳性率为50%,照此推算转化植株约占总植株的7%。目前部分转基因植株巳开花结实. 3.用pLX412 - Hb质粒基因枪法转化水稻幼胚及愈伤组织,抗性筛选得到15株再生植株,以Parasponia血红蛋白基因为探针进行点杂交,有14株为阳性结果,阳性率93%.取7株DNA点杂交呈阳性的植株DNA,以Parasponia血红蛋白基因为探针进行Southern杂交,都为阳性结果,阳性率为100%,照此推算转化植株约占总植株的93%.目前,部分转基因植株已开花结实. 4.用pLX412 -Hb质粒通过Agrobacterrum tumeFaciens LBA4404转化烟草,抗性筛选得到的再生植株以Parasponia血红蛋白基因为探针进行Southern杂交,结果为阳性. 5.用pLHB基因枪法转化的愈伤组织,抗性筛选得到已分化出绿芽点的愈伤组织,以Parasponia血红蛋白基因为探针或以豌豆凝集素基因为探针进行Southern杂交,杂交结果均为阳性. 6.最近国外巳发现大麦有血红蛋白基因.本论文以大麦血红蛋白cDNA为探针对未转基因的水稻进行Southern杂交,结果有阳性带。说明水稻有与大麦血红蛋白基因高度同源序列。以Parasponia血红蛋白基因为探针时杂交结果为阴性,说明水稻血红蛋白基因与Parasponiaa血红蛋白基因核苷酸序列相差较大. 7.提取Southern杂交证明有Parasponia血红蛋白基因整合的水稻根及叶总RNA,以Parasponia血红蛋白基因cDNA为探针进行RNA点杂交,结果根总RNA为阳性,叶总RNA为阴性。初步证明Parasponia血红蛋白基因在水稻根中表达。 8.提取未转基因的水稻根及叶RNA,以大麦血红蛋白基因cDNA为探针进行RNA点杂交,结果:根总RNA为阳性结果,叶总RNA为阴性结果.初步证明水稻血红蛋白基因在水稻根中表达。 总之,本论文证明已将Parasponia血红蛋白基因整合进水稻植株染色体,将豌豆凝集素基因、Parasponia血红蛋白基因整合进水稻愈伤组织染色体,初步证明水稻有血红蛋白基因,内外源血红蛋白基因都有组织特异性表达,从而为本研究的战略设想奠定初步基础。

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Shortspine thornyhead (Sebastolobus alascanus) abundance was estimated from 107 video transects at 27 stations recorded from a research submersible in 1991 off southeast Alaska at depths ranging from 165 to 355 m. Numbers of invertebrates in seven major taxa were estimated, as was substrate type. Thornyhead abundance ranged from 0 to 7.5/100 m2, with a mean of 1.22/100 m2, and was positively correlated with depth and amount of hard substrate. Invertebrate abundances were not significantly correlated with numbers of thornyheads. Shortspine thornyhead abundance estimates from this study were several times higher than estimates produced by bottom trawl surveys off southeast Alaska in 1990 and 1993, the two years of survey that encompassed the submersible transects; however, the trend of increasing abundance with depth was similar in the trawl surveys and in the submersible transects, suggesting that trawl surveys systematically underestimate abundance of shortspine thornyheads

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A total of thirty eight ripe ovaries from the specimens of Rita pavimentata, measuring 230 to 355 mm in total length (TL) and 250 to 750 g in total weight (TW), were selected to study the fecundity. The relationship between fecundity 'and total length (TL), total weight (TW) and ovary weight (OW) was found to be linear. The coefficient of co-relation 'r' of the above relationship was found to be 0.92, 0.94 and 0.96 respectively. All these values are highly significant (P=0.01) indicating a close relationship between compared parameters. However, as indicated by value of 'r' (0.96), the fecundity is more closely related to ovary weight and hence the ovary weight may be a better index of fecundity than the total body length or weight.

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The energy substrates lactate, pyruvate, and glucose were evaluated for supporting in vitro cytoplasmic maturation of rhesus monkey oocytes. A total of 321 cumulus-oocyte complexes (COCs) aspirated from greater than or equal to 1000 mum diameter follicles

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An experiment was conducted to assess the performance of mola (Amblyphmyngodon mola) in rice fish culture system with freshwater prawn Macrobrachium rosenbergii), Thai silver barb (Bm·bades ganianotus) and common carp (Cyprinus cmpia) for a period of 4 months at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh. Four treatments viz., treatment-I (T1) with A. mala and M. rosenbergii; treatmen t-II (T2) with A. mala, M. rosenbergii and B. gonianatus ; treatmentIII (T3) with A. mala, 1Vf. rosenbergii and C. cmpia, and treatment- IV (T4) as control (without fish) were used in triplicate. All treatments were equally fertilized with urea (200 kg/ha), TSP (150 kg/ha) and MP (75 kg/ha). The mean values of water quality parameters viz., temperature, dissolved oxygen, pH, nitrate-nitrogen showed a very small variations among different treatments, but phosphate-phosphorus and chlorophyll-a were relatively higher in T4 without fish (i.e., control). The fish production of 480.5 kg/ha in T3 was significantly higher than that of 355.6 kg/ha T2 and 223.8 kg/ha in T 1• The values of soil organic matter, total-nitrogen, phosphorus and potassium at harvest were significantly (P<0.05) higher in the treatments with fish than without fish, but pH did not show any significant differences. The yield of rice grain and straw was also obtained significantly (P<0.05) higher in the treatments with fish. The increase in grain was higher over the control by 11.81%, 9.41% and 14.76% and that in straw was by 9.83%, 4.77% and 13.29% in Tl> T2, and T3 respectively.

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目的:研究槐花提取化合物K3的体外抗HIV-1活性,并对其抗HIV-1机制进行初步探讨.方法:采用MTT比色法检测化合物对各种细胞的毒性.用合胞体形成计数法,p24抗原捕获ELISA法及RT-PCR等多种方法研究化合物体外抗HIV-1活性.结论:槐花提取化合物K3体外有较好的抗HIV-1活性,能够抑制病毒实验株(HIV-1ⅢB,耐药株(HIV-1 74v)和临床分离株(HIV-1KM018)等多种病毒株的复制,且其作用机制是多靶点的,不仅可以抑制病毒的进入,还可以抑制HIV-1逆转录酶活性.