Time-resolved X-ray diffraction studies of the B in equilibrium D structural transition in the DNA double helix     

A Mahendrasingam  V T Forsyth  R Hussain  R J Greenall  W J Pigram  W Fuller 《Science (New York, N.Y.)》1986,233(4760):195-197

Because of the relation between topology and function, there has been much interest in the structural transitions of the various conformations of DNA polymers. The x-ray fiber diffraction analysis system at the Daresbury Synchrotron Radiation Source was used to study the reversible transition between the B and D forms of the synthetic DNA poly[d(A-T)].poly[d(A-T)]. The gradual progression of conformations between these two forms indicates that the DNA double helix does not undergo a change of handedness during this transition.  相似文献   

Cancer. A skin cancer virus?     

Viscidi RP  Shah KV 《Science (New York, N.Y.)》2008,319(5866):1049-1050

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Neuroscience. Making synapses: a balancing act     

Hussain NK  Sheng M 《Science (New York, N.Y.)》2005,307(5713):1207-1208

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Microbial dehalorespiration with 1,1,1-trichloroethane     

Sun B  Griffin BM  Ayala-del-Río HL  Hashsham SA  Tiedje JM 《Science (New York, N.Y.)》2002,298(5595):1023-1025

1,1,1-Trichloroethane (TCA) is a ubiquitous environmental pollutant because of its widespread use as an industrial solvent, its improper disposal, and its substantial emission to the atmosphere. We report the isolation of an anaerobic bacterium, strain TCA1, that reductively dechlorinates TCA to 1,1-dichloroethane and chloroethane. Strain TCA1 required H2 as an electron donor and TCA as an electron acceptor for growth, indicating that dechlorination is a respiratory process. Phylogenetic analysis indicated that strain TCA1 is related to gram-positive bacteria with low DNA G+C content and that its closest relative is Dehalobacter restrictus, an obligate H2-oxidizing, chloroethene-respiring bacterium.  相似文献   

From a single-band metal to a high-temperature superconductor via two thermal phase transitions     

He RH  Hashimoto M  Karapetyan H  Koralek JD  Hinton JP  Testaud JP  Nathan V  Yoshida Y  Yao H  Tanaka K  Meevasana W  Moore RG  Lu DH  Mo SK  Ishikado M  Eisaki H  Hussain Z  Devereaux TP  Kivelson SA  Orenstein J  Kapitulnik A  Shen ZX 《Science (New York, N.Y.)》2011,331(6024):1579-1583

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at T* of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T(c)), entangled in an energy-momentum-dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.  相似文献   

Using leaf tip necrosis as a phenotypic marker to predict the presence of durable rust resistance gene pair <Emphasis Type="Italic">Lr34</Emphasis>/<Emphasis Type="Italic">Yr18</Emphasis> in wheat     

Syed Jawad Ahmad Shah  Shaukat Hussain  Musharaf Ahmad  Farhatullah  Iftikhar Ali  Muhammad Ibrahim 《Journal of General Plant Pathology》2011,77(3):174-177

Fifty wheat varieties along with Jupateco-73 and Morocco were studied for the expression of leaf tip necrosis (LTN), a trait linked with the durable rust resistance gene pair Lr34/Yr18. LTN was frequent (i.e., ≥6) in nine replications of a field experiment over 3 years in 17 genotypes, and the varieties were considered positive for LTN. In molecular analyses of these varieties, having relative severity values up to 78 for yellow rust and 45 for leaf rust, the 150-bp Lr34/Yr18-linked allele was consistently amplified. Expression of LTN in six of nine replications is an appropriate threshold for predicting the presence of Lr34/Yr18 gene pair, and genotypes can be selected using this trait.  相似文献   

Soil C and N dynamics and maize (Zea may L.) yield as affected by cropping systems and residue management in North-western Pakistan     

Mohammad Shafi  Jehan Bakht  Mohammad Tariq Jan  Zahir Shah 《Soil & Tillage Research》2007,94(2):520-529

This paper presents the results of irrigated rotation experiment, conducted in the North West Frontier Province (NWFP), Pakistan, during 1999–2002 to evaluate effects of residues retention, fertilizer N and legumes in crop rotation on yield of maize (Zea mays L.) and soil organic fertility. Chickpea (Cicer arietinum L) and wheat (Triticum aestivum L) were grown in the winters and mungbean (Vigna radiata) and maize in the summers. Immediately after grain harvest, above-ground residues of all crops were either completely removed (−residue), or spread across the plots and incorporated by chisel plough by disc harrow and rotavator (+residue). Fertlizer N rates were nil or 120 kg ha⁻¹ for wheat and nil or 160 kg ha⁻¹ for maize. Our results indicated that post-harvest incorporation of crop residues significantly (p < 0.05) increased the grain and stover yields of maize during both 2000 and 2001. On average, grain yield was increased by 23.7% and stover yield by 26.7% due to residue incorporation. Residue retention also enhanced N uptake by 28.3% in grain and 45.1% in stover of maize. The soil N fertility was improved by 29.2% due to residue retention. The maize grain and stover yields also responded significantly to the previous legume (chickpea) compared with the previous cereal (wheat) treatment. The legume treatment boosted grain yield of maize by 112% and stover yield by 133% with 64.4% increase in soil N fertility. Similarly, fertilizer N applied to previous wheat showed considerable carry over effect on grain (8.9%) and stover (40.7%) yields of the following maize. Application of fertilizer N to current maize substantially increased grain yield of maize by 110%, stover yield by 167% and soil N fertility by 9.8% over the nil N fertilizer treatment. We concluded from these experiments that returning of crop residues, application of fertilizer N and involvement of legumes in crop rotation greatly improves the N economy of the cropping systems and enhances crop productivity through additional N and other benefits in low N soils. The farmers who traditionally remove residues for fodder and fuel will require demonstration of the relative benefits of residues return to soil for sustainable crop productivity.  相似文献   

Subcellular compartmentation of sugars in wheat leaves under the influence of salinity and boron toxicity     

Sajid Masood  Muhammad Iqbal  Hassan Javed Chaudhary  M. Farooq Hussain Munis 《Journal of plant nutrition》2016,39(14):2100-2105

In this study, long-term effects of salinity and high boron (B) on subcellular distribution of sugars in wheat leaves were investigated. Four treatments with three replications of each; control, high B, sodium chloride (NaCl) and NaCl + high B, respectively were established according to completely randomized design. Plants were grown hydroponically and harvested after 6 weeks onset of experiment. NaCl treatment markedly decreased the shoot fresh and dry weight compared to high B or NaCl + high Boron. It increased the sugar concentrations in subcellular compartments, whereas decreased in NaCl + high B. Contrary, NaCl either alone or in combination with high B decreased the sugar contents in whole leaf compared to control or high B. Overall, higher concentrations of sugars were observed in symplast compared to apoplast indicating the symplast as major compartment for sugar transport. Furthermore, wheat plants accumulate sugars in subcellular compartments to maintain their growth under stress conditions.  相似文献   

Boron-Calcium Synergically Alleviates Aluminum Toxicity in Wheat Plants (Triticum aestivum L.)     

A. K. M. Zakir Hossain  Md. Ali Asgar  M. Alamgir Hossain  Toshihiko Tosaki  Hiroyuki Koyama  Tetsuo Hara 《Soil Science and Plant Nutrition》2005,51(1):43-49

The effects of B and Ca treatments on root growth, nutrient localization and cell wall properties in wheat ( Triticum aestivum L.) plants with and without Al stress were investigated. Seedlings were grown hydroponically in a complete nutrient solution for 7 d and then treated with B (0, 40 μM), Ca (0, 2,500 μM), and Al (0, 100 μM) in a 500 μM CaCl₂ solution for 8 d. The cell wall materials (CWM) were extracted with a phenol: acetic acid: water (2:1:1 w/v/v) solution and used for subsequent pectin extraction with trans -1,2-diami-nocyclohexane- N,N,N,N -tetraacetic acid (CDTA) and Na₂CO₃ solutions. Boron, Ca, and B + Ca treatments enhanced root growth by 19.5, 15.2, and 27.2%, respectively, compared to the control (pH 4.5). Calcium and B+Ca treatments enhanced root growth with Al stress by 43 and 54%, respectively, while B did not exert any effect. The amounts of CWM and pectin per unit of root fresh weight increased by Al treatment, whereas the Ca and B+Ca treatments slightly reduced the contents of these components. Seventy-four percent of total B, 69% of total Ca, and 85% of total Al were located in the cell wall in the B, Ca, and Al treatments, respectively and 32% of total B, 33% of total Ca, and 33% of total Al were located in the CDTA-soluble and Na₂CO₃-soluble pectin fractions. A more conspicuous localization of B was observed in the presence of Al. Aluminum treatment markedly decreased the Ca content in the cell wall as well as pectin fractions, mainly in the case of the CDTA-soluble pectin fraction. Boron + Ca treatment decreased the Al content in the cell wall and pectin fractions compared to the Ca treatment alone in the presence of Al. It is concluded that the B+Ca treatment enhanced root growth and, B and Ca uptake, and helped to maintain a normal B and Ca metabolism in the cell walls even in the presence of Al.  相似文献   

Metal chemistry of irrigation and drainage waters of Al-Ahsa Oasis of Saudi Arabia and its effects on soil properties     

Hussain  G.  Sadiq  M 《Water, air, and soil pollution》1991,(1):773-783

Water samples from 18 springs and 13 drainage canals and subcanals were collected from Al-Ahsa Oasis. Concentrations of total dissolved salts, Cl, SO₄ HCO₃, B, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, V, Ti, and Zn were determined. The soil salinity development (SSD), the adjusted Na ratio (adj. SAR), the adjusted Na adsorption ratio (adj. RNa), and exchangeable Na percentage (ESP) were calculated. Sodium was the most abundant cation in all water samples followed by Ca, Mg, Sr, and K in descending order. Concentrations of all other metals were below 0.1 mg L^–1. Chloride was the most abundant anion, followed by SO₄ and HCO₃ in these waters. A significant correlation (P < 0.05)=" between=" na=" and=" cl=" in=" water=" samples=" was=" found.=" thermodynamic=" calculations=" revealed=" that=" an=" appreciable=" fraction=" of=" ca=" and=" mg=" in=" spring=" and=" drainage=" waters=" were=" associated=" with=">₄ and HCO₃ ions. Calcium increased from less than 10 meq L^–1 in spring waters to > 16 meq L^–1, Mg was doubled, and Na and Cl increased several times in the drainage waters. The salinity and sodicity hazards of the spring and drainage waters were classified as C₄S₂ i.e. high salinity with medium sodicity problems.  相似文献