A model to simulate response of plant stomata to environmental conditions     

Roni Avissar  Patricia Avissar  Ytzhaq Mahrer  Ben Ami Bravdo 《Agricultural and Forest Meteorology》1985,34(1):21-29

In order to simulate plant transpiration under different field climatic conditions we have developed and verified a semi-empirical model for predicting the stomatal response to solar global radiation, leaf temperature, vapour pressure difference between the leaf and ambient air, ambient air CO₂ concentration and soil water potential. The transpiration and the stomatal relative conductance of a Nicotania Tabaccum var “samsun” plant leaves were measured in a laboratory apparatus and compared to those predicted by the model: good agreement was obtained between them for the different investigated cases. The model was incorporated in a numerical greenhouse microclimate model and its effects on the canopy microclimate are discussed here.  相似文献   

Investigation of pollen competition between wild and cultivated sorghums (<Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.) Moench) using simple sequence repeats markers     

Moses M. Muraya  Hartwig H. Geiger  Santie de Villiers  Fabrice Sagnard  Ben M. Kanyenji  Dan Kiambi  Heiko K. Parzies 《Euphytica》2011,178(3):393-401

In self-compatible plant species stigmata receive a mixture of self and outcrossed pollen and competition between them is expected to play a major role in determining the pollen-mediated gene flow. The use of male sterile bait plants in field trials to demonstrate the rate of gene flow is questionable due to lack of pollination competition. However, little direct evidence has been published. A field experiment of male sterile and male fertile sorghum pollen recipient bait plants was conducted to evaluate pollen competition between wild and cultivated sorghums and the effects of pollen competition on gene flow assessment. Pollen competition between wild and cultivated sorghums was estimated from two-component pollen mixtures of wild and cultivated sorghum (1:1 ratio) applied to wild, cultivated and male-sterile maternal bait plants. Paternity was determined in the progeny using two diagnostic Simple Sequence Repeat markers. The study found that self pollen has higher seed-siring success. Maternal genotype influences the siring ability of the pollen donor components which significantly deviated from the 1:1 pollen loads. The study showed that published estimates of gene flow derived from studies using male-sterile bait plants seriously overestimate gene flow and that pollen competition may be a significant factor influencing outcrossing rates. The results suggest that the predominant direction of gene flow is from cultivated to wild sorghum, potentially leading to introgression of crop genes into wild sorghum. Pollen competition should be taken into account in gene flow estimation, since presence of self-pollen can account for over half of seed produced irrespective of maternal genotype.  相似文献   

小麦-黑麦远缘杂交后代储藏蛋白遗传变异分析   总被引：3，自引：0，他引：3  

宋振巧  晏本菊  任正隆  张怀渝  傅体华 《四川农业大学学报》2001,19(4):411-414

运用A PAGE和SDS PAGE电泳技术分析了 85份小麦 -黑麦远缘杂交后代及母本绵阳 11的种子储藏蛋白组成。结果为 :① 78 8%的材料在醇溶蛋白的ω区不同于亲本绵阳 11,其中 5 6 5 %的材料具有黑麦的特征带型Gli B1l,属于 1B/ 1R染色体易位 ,另外的 2 2 3%的变异材料与绵阳 11的差异在于 1～ 2条带纹的有无或表达剂量的不同 ;②供试材料中共分离出 7种高分子量谷蛋白亚基类型 ,其中母本绵阳 11的亚基在各位点上所占比例最高 ,亚基 1(5 3% )、7+8(5 4 % )、5 +10 (87% ) ,在非母本类型中N和 7+9的比例也较高 ;在 85份供试材料中共检测到 8种亚基组合 ,其中母本类型 (1,7+8,5 +10 )和非母本类型 (N ,7+9,5 +10 )占有较高的比例 ,分别为 36 5 %、31 7%。上述结果说明 ,运用单体附加外源染色体将黑麦基因引入普通小麦后可引起杂交后代醇溶蛋白和高分子麦谷蛋白亚基的变异 ,获得较多的变异材料 ,这些材料对丰富普通小麦的遗传资源以及对小麦品质的改良将会有重要作用。本文还对引起变异的原因等问题进行了探讨  相似文献   

Amacrine-signaled loss of intrinsic axon growth ability by retinal ganglion cells     

Goldberg JL  Klassen MP  Hua Y  Barres BA 《Science (New York, N.Y.)》2002,296(5574):1860-1864

The central nervous system (CNS) loses the ability to regenerate early during development, but it is not known why. The retina has long served as a simple model system for study of CNS regeneration. Here we show that amacrine cells signal neonatal rat retinal ganglion cells (RGCs) to undergo a profound and apparently irreversible loss of intrinsic axon growth ability. Concurrently, retinal maturation triggers RGCs to greatly increase their dendritic growth ability. These results suggest that adult CNS neurons fail to regenerate not only because of CNS glial inhibition but also because of a loss of intrinsic axon growth ability.  相似文献   

Assembly mechanism of the contractile ring for cytokinesis by fission yeast     

Vavylonis D  Wu JQ  Hao S  O'Shaughnessy B  Pollard TD 《Science (New York, N.Y.)》2008,319(5859):97-100

Animals and fungi assemble a contractile ring of actin filaments and the motor protein myosin to separate into individual daughter cells during cytokinesis. We used fluorescence microscopy of live fission yeast cells to observe that membrane-bound nodes containing myosin were broadly distributed around the cell equator and assembled into a contractile ring through stochastic motions, after a meshwork of dynamic actin filaments appeared. Analysis of node motions and numerical simulations supported a mechanism whereby transient connections are established when myosins in one node capture and exert force on actin filaments growing from other nodes.  相似文献   

Physical one-way functions     

Pappu R  Recht B  Taylor J  Gershenfeld N 《Science (New York, N.Y.)》2002,297(5589):2026-2030

Modern cryptographic practice rests on the use of one-way functions, which are easy to evaluate but difficult to invert. Unfortunately, commonly used one-way functions are either based on unproven conjectures or have known vulnerabilities. We show that instead of relying on number theory, the mesoscopic physics of coherent transport through a disordered medium can be used to allocate and authenticate unique identifiers by physically reducing the medium's microstructure to a fixed-length string of binary digits. These physical one-way functions are inexpensive to fabricate, prohibitively difficult to duplicate, admit no compact mathematical representation, and are intrinsically tamper-resistant. We provide an authentication protocol based on the enormous address space that is a principal characteristic of physical one-way functions.  相似文献   

Anthropology. Tracking Polynesian seafarers     

Finney B 《Science (New York, N.Y.)》2007,317(5846):1873-1874

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侧孢短芽孢杆菌的应用研究进展   总被引：1，自引：0，他引：1  

陈潺  陈升富  王建宇  张铭铄  殷犇  毛志泉  周波  王冰 《山东农业科学》2015,(2):149-156

侧孢短芽孢杆菌(Brevibacillus laterosporus)具有杀虫、抗菌、抗肿瘤、生物降解转化等多种生物学活性,在生物防治、环境保护、医学、微生物菌剂开发等诸多方面显示了巨大的应用价值和潜力。本文综述了侧孢短芽孢杆菌自被发现以来的主要研究成果及相应研究方法,重点关注了侧孢短芽孢杆菌在生产上具体应用的进展状况,部分内容系国内首次提及。同时,还指出了在侧孢短芽孢杆菌应用中存在的问题,并对其未来的研发和应用进行了展望。  相似文献   

Mutations in the DJ-1 gene associated with autosomal recessive early-onset parkinsonism     

Bonifati V  Rizzu P  van Baren MJ  Schaap O  Breedveld GJ  Krieger E  Dekker MC  Squitieri F  Ibanez P  Joosse M  van Dongen JW  Vanacore N  van Swieten JC  Brice A  Meco G  van Duijn CM  Oostra BA  Heutink P 《Science (New York, N.Y.)》2003,299(5604):256-259

The DJ-1 gene encodes a ubiquitous, highly conserved protein. Here, we show that DJ-1 mutations are associated with PARK7, a monogenic form of human parkinsonism. The function of the DJ-1 protein remains unknown, but evidence suggests its involvement in the oxidative stress response. Our findings indicate that loss of DJ-1 function leads to neurodegeneration. Elucidating the physiological role of DJ-1 protein may promote understanding of the mechanisms of brain neuronal maintenance and pathogenesis of Parkinson's disease.  相似文献   

Recalibrating plant water status of winter wheat based on nitrogen nutrition index using thermal images     

Zhao  Ben  Adama  Traore  Ata-Ul-Karim  Syed Tahir  Guo  Yan  Liu  Zhandong  Xiao  Junfu  Liu  Zugui  Qin  Anzhen  Ning  Dongfeng  Duan  Aiwang 《Precision Agriculture》2022,23(3):748-767

Precision Agriculture - Accurate and timely assessment of crop water status is imperative for in-season irrigation scheduling in crop production. The canopy water stress index and water deficit...  相似文献