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61.
Srinivasan Samineni Pooran M. Gaur Timothy D. Colmer L. Krishnamurthy Vincent Vadez Kadambot H. M. Siddique 《Euphytica》2011,182(1):73-86
Chickpea (Cicer arietinum L.) is known to be salt-sensitive and in many regions of the world its yields are restricted by salinity. Recent identification
of large variation in chickpea yield under salinity, if genetically controlled, offers an opportunity to develop cultivars
with improved salt tolerance. Two chickpea land races, ICC 6263 (salt sensitive) and ICC 1431 (salt tolerant), were inter-crossed
to study gene action involved in different agronomic traits under saline and control conditions. The generation mean analysis
in six populations, viz. P1, P2, F1, F2, BC1P1 and BC1P2, revealed significant gene interactions for days to flowering, days to maturity, and stem Na and K concentrations in control
and saline treatments, as well as for 100-seed weight under salinity. Seed yield, pods per plant, seeds per plant, and stem
Cl concentration were controlled by additive effects under saline conditions. Broad-sense heritability values (>0.5) for most
traits were generally higher in saline than in control conditions, whereas the narrow-sense heritability values for yield
traits, and stem Na and K concentrations, were lower in saline than control conditions. The influence of the sensitive parent
was higher on the expression of different traits; the additive and dominant genes acted in opposite directions which led to
lower heritability estimates in early generations. These results indicate that selection for yield under salinity would be
more effective in later filial generations after gene fixation. 相似文献
62.
Nathan?C.?HealeyEmail author Ayse?Irmak Timothy?J.?Arkebauer David?P.?Billesbach John?D.?Lenters Kenneth?G.?Hubbard Richard?G.?Allen Jeppe?Kjaersgaard 《Irrigation and Drainage Systems》2011,25(3):151-178
Water consumed through evapotranspiration (ET) impacts local and regional hydrologic regimes on various spatial and temporal
scales. Estimating ET in the Great Plains is a prerequisite for effective regional water resource management of the Ogallala
(High Plains) Aquifer, which supplies vital water resources in the form of irrigation for extensive agricultural production.
The Sand Hills region of Nebraska is one of the largest grass-stabilized eolian (windblown) sand dune formations in the world,
with an area of roughly 50,000–60,000 km2 that supports a system of five major land cover types: (1) lakes, (2) wetlands (with lakes, ~5%), (3) subirrigated meadows
(water table is within ~1 m of surface; ~10%), (4) dry valleys (water table is 1–10 m below surface; ~20%), and (5) upland
dunes (water table is more than 10 m below surface; ~65%). Fully understanding the hydrologic regime of these different ecosystems
is a fundamental challenge in regional water resource assessment. The surface energy and water balances were analyzed using
Bowen Ratio Energy Balance Systems (BREBS) at three locations: (1) a meadow, (2) a valley, and (3) an upland dune. Measurement
of the energy budget by BREBS, in concert with Landsat remote sensing image processing for 2004 reveals strong spatial gradients
between sites in latent heat flux that are associated with undulating topographic relief. We find that daily estimates of
ET from BREBS measurements and remote sensing agree well, with an uncertainty within 1 mm, which is encouraging when applying
remote sensing results across such a broad spatial scale and undulating topography. 相似文献
63.
The mTOR-regulated phosphoproteome reveals a mechanism of mTORC1-mediated inhibition of growth factor signaling 总被引:1,自引:0,他引:1
Hsu PP Kang SA Rameseder J Zhang Y Ottina KA Lim D Peterson TR Choi Y Gray NS Yaffe MB Marto JA Sabatini DM 《Science (New York, N.Y.)》2011,332(6035):1317-1322
The mammalian target of rapamycin (mTOR) protein kinase is a master growth promoter that nucleates two complexes, mTORC1 and mTORC2. Despite the diverse processes controlled by mTOR, few substrates are known. We defined the mTOR-regulated phosphoproteome by quantitative mass spectrometry and characterized the primary sequence motif specificity of mTOR using positional scanning peptide libraries. We found that the phosphorylation response to insulin is largely mTOR dependent and that mTOR exhibits a unique preference for proline, hydrophobic, and aromatic residues at the +1 position. The adaptor protein Grb10 was identified as an mTORC1 substrate that mediates the inhibition of phosphoinositide 3-kinase typical of cells lacking tuberous sclerosis complex 2 (TSC2), a tumor suppressor and negative regulator of mTORC1. Our work clarifies how mTORC1 inhibits growth factor signaling and opens new areas of investigation in mTOR biology. 相似文献
64.
Mitton-Fry RM Anderson EM Hughes TR Lundblad V Wuttke DS 《Science (New York, N.Y.)》2002,296(5565):145-147
The essential Cdc13 protein in the yeast Saccharomyces cerevisiae is a single-stranded telomeric DNA binding protein required for chromosome end protection and telomere replication. Here we report the solution structure of the Cdc13 DNA binding domain in complex with telomeric DNA. The structure reveals the use of a single OB (oligonucleotide/oligosaccharide binding) fold augmented by an unusually large loop for DNA recognition. This OB fold is structurally similar to OB folds found in the ciliated protozoan telomere end-binding protein, although no sequence similarity is apparent between them. The common usage of an OB fold for telomeric DNA interaction demonstrates conservation of end-protection mechanisms among eukaryotes. 相似文献
65.
Multimillion-atom molecular-dynamics simulations are used to investigate the shock-induced phase transformation of solid iron. Above a critical shock strength, many small close-packed grains nucleate in the shock-compressed body-centered cubic crystal growing on a picosecond time scale to form larger, energetically favored grains. A split two-wave shock structure is observed immediately above this threshold, with an elastic precursor ahead of the lagging transformation wave. For even higher shock strengths, a single, overdriven wave is obtained. The dynamics and orientation of the developing close-packed grains depend on the shock strength and especially on the crystallographic shock direction. Orientational relations between the unshocked and shocked regions are similar to those found for the temperature-driven martensitic transformation in iron and its alloys. 相似文献
66.
Although critical for development, immunity, wound healing, and metastasis, integrins represent one of the few classes of plasma membrane receptors for which the basic signaling mechanism remains a mystery. We investigated cytoplasmic conformational changes in the integrin LFA-1 (alphaLbeta2) in living cells by measuring fluorescence resonance energy transfer between cyan fluorescent protein-fused and yellow fluorescent protein-fused alphaL and beta2 cytoplasmic domains. In the resting state these domains were close to each other, but underwent significant spatial separation upon either intracellular activation of integrin adhesiveness (inside-out signaling) or ligand binding (outside-in signaling). Thus, bidirectional integrin signaling is accomplished by coupling extracellular conformational changes to an unclasping and separation of the alpha and beta cytoplasmic domains, a distinctive mechanism for transmitting information across the plasma membrane. 相似文献
67.
Maintenance of genomic methylation patterns is mediated primarily by DNA methyltransferase-1 (DNMT1). We have solved structures of mouse and human DNMT1 composed of CXXC, tandem bromo-adjacent homology (BAH1/2), and methyltransferase domains bound to DNA-containing unmethylated CpG sites. The CXXC specifically binds to unmethylated CpG dinucleotide and positions the CXXC-BAH1 linker between the DNA and the active site of DNMT1, preventing de novo methylation. In addition, a loop projecting from BAH2 interacts with the target recognition domain (TRD) of the methyltransferase, stabilizing the TRD in a retracted position and preventing it from inserting into the DNA major groove. Our studies identify an autoinhibitory mechanism, in which unmethylated CpG dinucleotides are occluded from the active site to ensure that only hemimethylated CpG dinucleotides undergo methylation. 相似文献
68.
Fairman ME Maroney PA Wang W Bowers HA Gollnick P Nilsen TW Jankowsky E 《Science (New York, N.Y.)》2004,304(5671):730-734
Members of the DExH/D superfamily of nucleic acid-activated nucleotide triphosphatases are essential for virtually all aspects of RNA metabolism, including pre-messenger RNA splicing, RNA interference, translation, and nucleocytoplasmic trafficking. Physiological substrates for these enzymes are thought to be regions of double-stranded RNA, because several DExH/D proteins catalyze strand separation in vitro. These "RNA helicases" can also disrupt RNA-protein interactions, but it is unclear whether this activity is coupled to duplex unwinding. Here we demonstrate that two unrelated DExH/D proteins catalyze protein displacement independently of duplex unwinding. Therefore, the essential functions of DExH/D proteins are not confined to RNA duplexes but can be exerted on a wide range of ribonucleoprotein substrates. 相似文献
69.
At geological time scales, the role of continental erosion in the organic carbon (OC) cycle is determined by the balance between recent OC burial and petrogenic OC oxidation. Evaluating its net effect on the concentration of carbon dioxide and dioxygen in the atmosphere requires the fate of petrogenic OC to be assessed. Here, we report a multiscale (nanometer to micrometer) structural characterization of petrogenic OC in the Himalayan system. We show that graphitic carbon is preserved and buried in marine sediments, while the less graphitized forms are oxidized during fluvial transport. Radiocarbon dating indicates that 30 to 50% of the carbon initially present in the Himalayan rocks is conserved during the erosion cycle. Graphitization during metamorphism thus stabilizes carbon in the crust over geological time scales. 相似文献
70.
Use of U.S. croplands for biofuels increases greenhouse gases through emissions from land-use change 总被引:3,自引:0,他引:3
Searchinger T Heimlich R Houghton RA Dong F Elobeid A Fabiosa J Tokgoz S Hayes D Yu TH 《Science (New York, N.Y.)》2008,319(5867):1238-1240
Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns about large biofuel mandates and highlights the value of using waste products. 相似文献