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排序方式: 共有891条查询结果,搜索用时 234 毫秒
71.
Antony M. Hooper Muniru K. Tsanuo Keith Chamberlain Kay Tittcomb Julie Scholes Ahmed Hassanali Zeyaur R. Khan John. A. Pickett 《Phytochemistry》2010,71(8-9):904-908
In East African small-holder farming of maize, the cattle forage legume, Desmodium uncinatum is used as an intercrop due to its allelopathic inhibition of parasitism by Striga hermonthica, an obligate parasitic weed that can devastate the maize crop. Bioassay-guided fractionation of the root extract of D. uncinatum revealed isoschaftoside to be the main compound in the most potent fraction inhibiting growth of germinated S. hermonthica radicles. Bioassays repeated with isoschaftoside isolated from a different plant source, Passiflora incarnata, proved it to be a biologically active component. Analysis of the root exudates produced by hydroponically grown D. uncinatum showed isoschaftoside to be present in the hydroponic media at biologically active concentrations of 10–100 nM. 相似文献
72.
73.
Erpenbeck D Nichols SA Voigt O Dohrmann M Degnan BM Hooper JN Wörheide G 《Journal of molecular evolution》2007,64(5):543-557
Many rDNA molecular phylogenetic studies result in trees that are incongruent to either alternative gene tree reconstructions
and/or morphological assumptions. One reason for this outcome might be the application of suboptimal phylogenetic substitution
models. While the most commonly implemented models describe the evolution of independently evolving characters fairly well,
they do not account for character dependencies such as rRNA strands that form a helix in the ribosome. Such nonindependent
sites require the use of models that take into account the coevolution of the complete nucleotide pair (doublet). We analyzed
28S rDNA (LSU) demosponge phylogenies using a “doublet” model for pairing sites (rRNA-helices) and compared our findings with
the results of “standard” approaches using Bayes factors. We demonstrate that paired and unpaired sites of the same gene result
in different reconstructions and that usage of a doublet model leads to more reliable demosponge trees. We show the influence
of more sophisticated models on phylogenetic reconstructions of early-branching metazoans and the phylogenetic relationships
of demosponge orders.
[Reviewing Editor: Dr. Rasmus Nielsen] 相似文献
74.
Reconnaissance and latent learning in ants 总被引:6,自引:0,他引:6
Franks NR Hooper JW Dornhaus A Aukett PJ Hayward AL Berghoff SM 《Proceedings. Biological sciences / The Royal Society》2007,274(1617):1505-1509
We show that ants can reconnoitre their surroundings and in effect plan for the future. Temnothorax albipennis colonies use a sophisticated strategy to select a new nest when the need arises. Initially, we presented colonies with a new nest of lower quality than their current one that they could explore for one week without a need to emigrate. We then introduced a second identical low quality new nest and destroyed their old nest so that they had to emigrate. Colonies showed a highly significant preference for the (low quality) novel new nest over the identical but familiar one. In otherwise identical experiments, colonies showed no such discrimination when the choice was between a familiar and an unfamiliar high-quality nest. When, however, either all possible pheromone marks were removed, or landmarks were re-orientated, just before the emigration, the ants chose between identical low-quality new nests at random. These results demonstrate for the first time that ants are capable of assessing and retaining information about the quality of potential new nest sites, probably by using both pheromones and landmark cues, even though this information may only be of strategic value to the colony in the future. They seem capable, therefore, of latent learning and, more explicitly, learning what not to do. 相似文献
75.
Buchanan MS Carroll AR Fechner GA Boyle A Simpson MM Addepalli R Avery VM Hooper JN Su N Chen H Quinn RJ 《Bioorganic & medicinal chemistry letters》2007,17(24):6860-6863
Isoprenylcysteine methyltransferase (Icmt) catalyzes the carboxyl methylation of oncogenic proteins in the final step of a series of post-translational modifications. The inhibition of Icmt provides an attractive and novel anticancer target. A natural product high-throughput screening campaign was conducted to discover inhibitors of Icmt. The Australian marine sponge, Pseudoceratina sp., yielded spermatinamine, a novel alkaloid with a bromotyrosyl-spermine-bromotyrosyl sequence, as the bioactive constituent. Its structure was determined by 1D and 2D NMR spectroscopy. Spermatinamine is the first natural product inhibitor of Icmt. 相似文献
76.
Flecknoe SJ Crossley KJ Zuccala GM Searle JE Allison BJ Wallace MJ Hooper SB 《American journal of physiology. Lung cellular and molecular physiology》2007,292(2):L454-L461
Although increased lung expansion markedly alters lung growth and epithelial cell differentiation during fetal life, the effect of increasing lung expansion after birth is unknown. We hypothesized that increased basal lung expansion, caused by ventilating newborn lambs with a positive end-expiratory pressure (PEEP), would stimulate lung growth and alter alveolar epithelial cell (AEC) proportions and decrease surfactant protein mRNA levels. Two groups of lambs were sedated and ventilated with either 0 cmH(2)O PEEP (controls, n = 5) or 10 cmH(2)O PEEP (n = 5) for 48 h beginning at 15 +/- 1 days after normal term birth. A further group of nonventilated 2-wk-old lambs was used for comparison. We determined wet and dry lung weights, DNA and protein content, a labeling index for proliferating cells, surfactant protein mRNA expression, and proportions of AECs using electron microscopy. Although ventilating lambs for 48 h with 10 cmH(2)O PEEP did not affect total lung DNA or protein, it significantly increased the proportion of proliferating cells in the lung when compared with nonventilated 2-wk-old controls and lambs ventilated with 0 cmH(2)O PEEP (control: 2.6 +/- 0.5%; 0 PEEP: 1.9 +/- 0.3%; 10 PEEP: 3.5 +/- 0.3%). In contrast, no differences were observed in AEC proportions or surfactant protein mRNA levels between either of the ventilated groups. This study demonstrates that increases in end-expiratory lung volumes, induced by the application of PEEP, lead to increased lung growth in mechanically ventilated 2-wk-old lambs but do not alter the proportions of AECs. 相似文献
77.
Hooper C Day R Slocombe R Handlinger J Benkendorff K 《Fish & shellfish immunology》2007,22(4):363-379
Increasing mariculture of abalone focuses attention on their immune and stress responses. For abalone, as well as many invertebrates, the function and relationship of these systems and how in vitro tests relate to them are not fully understood. This review focuses on research into the immune system and stress response conducted on abalone and on aspects that can be monitored in vitro. To fill the considerable knowledge gaps, we discuss work on other invertebrate taxa, concentrating on those closest to abalone, and making explicit the phylogenetic relations involved. The stress response appears to be very similar to that in vertebrates, but interpreting most immune responses remains problematic. Phylogeny must be considered: immune function tests derived from research into vertebrates or distantly related invertebrates should not be used in abalone until they have been validated in abalone by studies of susceptibility to pathogens. We suggest phagocytic activity of haemocytes and their efficiency in clearing bacteria are reliable parameters to measure, because they have been directly related to immune competency and are consistently depressed by stress. Carefully designed assays of antimicrobial activity may also be useful. Important aims of future research will be to investigate the relationship between growth, stress and robust immunity, and to develop tests that can be run on production animals, which accurately depict immune status. 相似文献
78.
Beste DJ Hooper T Stewart G Bonde B Avignone-Rossa C Bushell ME Wheeler P Klamt S Kierzek AM McFadden J 《Genome biology》2007,8(5):R89
Background
An impediment to the rational development of novel drugs against tuberculosis (TB) is a general paucity of knowledge concerning the metabolism of Mycobacterium tuberculosis, particularly during infection. Constraint-based modeling provides a novel approach to investigating microbial metabolism but has not yet been applied to genome-scale modeling of M. tuberculosis. 相似文献79.
Fibroblast-led collective invasion of carcinoma cells with differing roles for RhoGTPases in leading and following cells 总被引:5,自引:0,他引:5
Gaggioli C Hooper S Hidalgo-Carcedo C Grosse R Marshall JF Harrington K Sahai E 《Nature cell biology》2007,9(12):1392-1400
Imaging of collectively invading cocultures of carcinoma cells and stromal fibroblasts reveals that the leading cell is always a fibroblast and that carcinoma cells move within tracks in the extracellular matrix behind the fibroblast. The generation of these tracks by fibroblasts is sufficient to enable the collective invasion of the squamous cell carcinoma (SCC) cells and requires both protease- and force-mediated matrix remodelling. Force-mediated matrix remodelling depends on integrins alpha3 and alpha5, and Rho-mediated regulation of myosin light chain (MLC) activity in fibroblasts, but these factors are not required in carcinoma cells. Instead, carcinoma cells use Cdc42 and MRCK (myotonic dystrophy kinase-related CDC42-binding protein kinases) mediated regulation of MLC to follow the tracks generated by fibroblasts. 相似文献
80.
Jason J. Rudd Kostya Kanyuka Keywan Hassani-Pak Mark Derbyshire Ambrose Andongabo Jean Devonshire Artem Lysenko Mansoor Saqi Nalini M. Desai Stephen J. Powers Juliet Hooper Linda Ambroso Arvind Bharti Andrew Farmer Kim E. Hammond-Kosack Robert A. Dietrich Mikael Courbot 《Plant physiology》2015,167(3):1158-1185