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51.
L. N. Timergalina L. B. Vysotskaya S. Yu. Veselov G. R. Kudoyarova 《Russian Journal of Plant Physiology》2007,54(5):633-638
In wheat (Triticum durum Desf., cv. Bezenchukskaya 139) seedlings, an increase in irradiance from 20 to 400 μmol/(m2 s) PAR enhanced transpiration and increased stomatal conductance by three times on the background of reduced relative water content (RWC). After this treatment, leaves quickly ceased to grow and became even shrunk later. In 40 or 50 min, leaf growth was resumed. At this period, we observed an increase in hydraulic conductivity and RWC and also in leaf extensibility. As soon as 10 min after treatment, some changes in hormone content were noted. In the zones of leaf growth and its mature part, zeatin and zeatin riboside were accumulated, whereas ABA accumulation was observed in the zone of leaf growth and in the roots. The results obtained indicate that leaf expansion at increased irradiance was related to changes in cell-wall extensibility and hydraulic conductivity. The first effect could be due to cytokinin accumulation, whereas the second one, to ABA accumulation. 相似文献
52.
In anticipation of the publication of full revisions, a diagnosis of a new species of Droguetia is presented together with two new combinations for subspecies of Droguetia iners , a new combination for a species and a variety on Didymodoxa and a new combination for a subspecies of Australina pusilla . The name Elatostema trinerve Hochst. (1845) is shown to be conspecific with and antedate Urera cameroonensis Wedd. (1869). The new combination Urera trinervis is therefore made. 相似文献
53.
Rogers AR; Fraley AE; Bamshad MJ; Watkins WS; Jorde LB 《Molecular biology and evolution》1996,13(7):895-902
Mismatch distributions are histograms showing the pattern of nucleotide (or
restriction) site differences between pairs of individuals in a sample.
They can be used to test hypotheses about the history of population size
and subdivision (if selective neutrality is assumed) or about selection (if
a constant population size is assumed). Previous work has assumed that
mutations never strike the same site twice, an assumption that is called
the model of infinite sites. Fortunately, the results are surprisingly
robust even when this assumption is violated. We show here that (1)
confidence regions inferred using the infinite- sites model differ little
from those inferred using a model of finite sites with uniform
site-specific mutation rates, and (2) even when site- specific mutation
rates follow a gamma distribution, confidence regions are little changed
until the gamma shape parameter falls well below its plausible range, to
roughly 0.01. In addition, we evaluate and reject the proposition that
mismatch waves are produced by pooling data from several subdivisions of a
structured population.
相似文献
54.
Gregoire Masliah Christophe Maris Sebastian LB König Maxim Yulikov Florian Aeschimann Anna L Malinowska Julie Mabille Jan Weiler Andrea Holla Juerg Hunziker Nicole Meisner‐Kober Benjamin Schuler Gunnar Jeschke Frederic H‐T Allain 《The EMBO journal》2018,37(6)
The accurate cleavage of pre‐micro(mi)RNAs by Dicer and mi/siRNA guide strand selection are important steps in forming the RNA‐induced silencing complex (RISC). The role of Dicer binding partner TRBP in these processes remains poorly understood. Here, we solved the solution structure of the two N‐terminal dsRNA binding domains (dsRBDs) of TRBP in complex with a functionally asymmetric siRNA using NMR, EPR, and single‐molecule spectroscopy. We find that siRNA recognition by the dsRBDs is not sequence‐specific but rather depends on the RNA shape. The two dsRBDs can swap their binding sites, giving rise to two equally populated, pseudo‐symmetrical complexes, showing that TRBP is not a primary sensor of siRNA asymmetry. Using our structure to model a Dicer‐TRBP‐siRNA ternary complex, we show that TRBP's dsRBDs and Dicer's RNase III domains bind a canonical 19 base pair siRNA on opposite sides, supporting a mechanism whereby TRBP influences Dicer‐mediated cleavage accuracy by binding the dsRNA region of the pre‐miRNA during Dicer cleavage. 相似文献
55.
56.
荔枝胚胎败育与酚类抑制物质的关系 总被引:3,自引:0,他引:3
在荔枝 (LitchichinensisSonn .)胚胎败育发生期 ,以系统溶剂法从正常或败育胚珠中初步提取酚类抑制物质 ,通过TLC分离与纯化 ,用GC MS联用仪进一步分离鉴定 ,并以标准品核对。试验首次从荔枝胚珠中分离鉴定出酚类抑制物质对羟基苯甲酸 (p_HBA)。生物活性测定表明 ,p_HBA是一种很强的生长抑制物质。在败育胚珠中其含量及IAA氧化酶活性均显著高于正常胚珠 ,IAA水平则明显低于正常胚珠 (P <0 .0 1)。因此认为 ,p_HBA参与了荔枝胚胎发育的调节 ,高含量的p_HBA是通过促进IAA侧链的氧化并影响促进和抑制生长的物质之间的平衡而导致荔枝胚胎的败育 相似文献
57.
端粒是真核细胞染色体末端的重复DNA序列 ,其生物学功能是防止染色体DNA降解、末端融合、非正常重组和染色体的缺失[1] .由于存在“末端复制问题” ,随着老化人体细胞端粒重复序列长度不断缩短 ,但在生殖细胞中由于端粒酶的存在 ,端粒序列并不缩短 .端粒酶是由蛋白质和RNA构成的核蛋白 ,是依赖RNA的DNA聚合酶 ,在DNA3’端合成端粒重复序列[2 ] .研究表明 ,在 85 %~ 95 %的人肿瘤细胞中可以检测到端粒酶的活性[3 ,4 ] ,而在正常体细胞中除生殖细胞和造血干细胞等极少数细胞中存在端粒酶活性外 ,均检测不到端粒酶活性 ,这… 相似文献
58.
Effect of auxin producing and phosphate solubilizing bacteria on mobility of soil phosphorus,growth rate,and P acquisition by wheat plants 总被引:1,自引:0,他引:1
Guzel R. Kudoyarova Lidiya B. Vysotskaya Tatiana N. Arkhipova Ludmila Yu. Kuzmina Nailya F. Galimsyanova Ludmila V. Sidorova Ilusa M. Gabbasova Alexander I. Melentiev Stanislav Yu. Veselov 《Acta Physiologiae Plantarum》2017,39(11):253
Microorganisms capable of mobilizing phosphate promote plant growth, this activity being frequently accompanied by production of plant hormones auxins. However, the extent of contribution of these characteristics to promotion of plant growth remains unclear. Paenibacillus illinoisensis IB 1087 and Pseudomonas extremaustralis IB-Ki-13-1A strains were selected for their capacity to mobilize phosphates and to synthesize auxins in vitro. The effects of inoculating these bacteria on the content of mobile phosphorus in the soil as well as on the phosphorus and hormone content in wheat plants were studied and the observed responses were related to the changes in plant growth. Inoculation of bacteria into the soil increased P concentration in the plants suggesting their increased capacity for the efficient acquisition of phosphorus compounds, while concentration of mobile phosphorus in the soil was increased by its inoculation with bacteria only in the absence of plants. The treatment increased plants mass (to greater extent in the case of P. illinoisensis) in accordance with the increased level of auxins in the treated plant. Increased mass accumulation did not correlate with the potential ability of bacteria strains for production of auxins or phosphate mobilization in vitro. Our data indicate importance of increased auxin content in the plants for the stimulation of root growth and capacity for P uptake as influenced by growth-promoting bacteria. 相似文献
59.
A. V. Cherkozianova L. B. Vysotskaya S. Yu. Veselov G. R. Kudoyarova 《Russian Journal of Plant Physiology》2005,52(5):629-634
We measured the content of hormones, the rate of growth, and some parameters of water regime (water content, transpiration, and stomatal and hydraulic conductivities) one and two days after wheat plant transfer from 10 to 1% Hoagland-Arnon nutrient medium. It was shown that, a day after dilution of nutrient solution, the content of various cytokinin forms decreased in the xylem sap, shoots, and roots. This decrease was most pronounced in the case of zeatin in the xylem sap and zeatin riboside in the mature zone of the first leaf. ABA was found to accumulate in shoots. A day after dilution of nutrient solution, we observed root elongation evidently induced by mineral nutrient deficiency, and this accelerated root growth was maintained later. Two days after dilution of nutrient solution, we observed the slowing of shoot weight accumulation, whereas root weight remained unchanged. Plant growth response could be related to ABA accumulation in shoots and cytokinin depletion in the whole plant. A reduced hydraulic conductivity and water content in the growing leaf zone was detected only two days after dilution of nutrient solution. Thus, changes in the growth rates and hormone contents could not result from disturbances in water regime induced by mineral nutrient deficiency. 相似文献
60.