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991.
Borglin S Joyner D Jacobsen J Mukhopadhyay A Hazen TC 《Journal of microbiological methods》2009,76(2):159-168
Growing anaerobic microorganisms in phenotypic microarrays (PM) and 96-well microtiter plates is an emerging technology that allows high throughput survey of the growth and physiology and/or phenotype of cultivable microorganisms. For non-model bacteria, a method for phenotypic analysis is invaluable, not only to serve as a starting point for further evaluation, but also to provide a broad understanding of the physiology of an uncharacterized wild-type organism or the physiology/phenotype of a newly created mutant of that organism. Given recent advances in genetic characterization and targeted mutations to elucidate genetic networks and metabolic pathways, high-throughput methods for determining phenotypic differences are essential. Here we outline challenges presented in studying the physiology and phenotype of a sulfate-reducing anaerobic delta proteobacterium, Desulfovibrio vulgaris Hildenborough. Modifications of the commercially available OmniLog system (Hayward, CA) for experimental setup, and configuration, as well as considerations in PM data analysis are presented. Also highlighted here is data viewing software that enables users to view and compare multiple PM data sets. The PM method promises to be a valuable strategy in our systems biology approach to D. vulgaris studies and is readily applicable to other anaerobic and aerobic bacteria. 相似文献
992.
Intact amino acid uptake by northern hardwood and conifer trees 总被引:1,自引:0,他引:1
Anne Gallet-Budynek Edward Brzostek Vikki L. Rodgers Jennifer M. Talbot Sharon Hyzy Adrien C. Finzi 《Oecologia》2009,160(1):129-138
Empirical and modeling studies of the N cycle in temperate forests of eastern North America have focused on the mechanisms
regulating the production of inorganic N, and assumed that only inorganic forms of N are available for plant growth. Recent
isotope studies in field conditions suggest that amino acid capture is a widespread ecological phenomenon, although northern
temperate forests have yet to be studied. We quantified fine root biomass and applied tracer-level quantities of U–13C2–15N-glycine, 15NH4
+ and 15NO3
− in two stands, one dominated by sugar maple and white ash, the other dominated by red oak, beech, and hemlock, to assess
the importance of amino acids to the N nutrition of northeastern US forests. Significant enrichment of 13C in fine roots 2 and 5 h following tracer application indicated intact glycine uptake in both stands. Glycine accounted for
up to 77% of total N uptake in the oak–beech–hemlock stand, a stand that produces recalcitrant litter, cycles N slowly and
has a thick, amino acid-rich organic horizon. By contrast, glycine accounted for only 20% of total N uptake in the sugar maple
and white ash stand, a stand characterized by labile litter and rapid rates of amino acid production and turnover resulting
in high rates of mineralization and nitrification. This study shows that amino acid uptake is an important process occurring
in two widespread, northeastern US temperate forest types with widely differing rates of N cycling. 相似文献
993.
Endophytic bacteria associated with sweet potato plants (Ipomoea batatas (L.) Lam.) were isolated, identified and tested for their ability to fix nitrogen, produce indole acetic acid (IAA), and exhibit stress tolerance. Eleven different strains belonging to the genera, Enterobacter, Rahnella, Rhodanobacter, Pseudomonas, Stenotrophomonas, Xanthomonas and Phyllobacterium, were identified. Four strains were shown to produce IAA (a plant growth hormone) and one strain showed the ability to grow in nitrogen free medium and had the nitrogenase subunit gene, nifH. To determine if IAA production by the endophytes had any role in protecting the cells against adverse conditions, different stress tests were conducted. The IAA producer grew well in the presence of some antibiotics, UV and cold treatments but the response to pH, osmotic shock, thermal and oxidative treatments was the same for both the IAA producer and the no IAA producer. To determine if IAA produced by the strains was biologically relevant to plants, cuttings of poplar were inoculated with the highest IAA producing strain. The inoculated cuttings produced roots sooner and grew more rapidly than uninoculated cuttings. These studies indicate that endophytes of sweet potato plants are beneficial to plant growth. 相似文献
994.
Sharon Stanton Olivier Honnay Hans Jacquemyn Isabel Roldán-Ruiz 《Plant Systematics and Evolution》2009,281(1-4):161-169
Parasite populations do not necessarily conform to expected patterns of genetic diversity and structure. Parasitic plants may be more vulnerable to the negative consequences of landscape fragmentation because of their specialized life history strategies and dependence on host plants, which are themselves susceptible to genetic erosion and reduced fitness following habitat change. We used AFLP genetic markers to investigate the effects of habitat fragmentation on genetic diversity and structure within and among populations of hemiparasitic Viscum album. Comparing populations from two landscapes differing in the amount of forest fragmentation allowed us to directly quantify habitat fragmentation effects. Populations from both landscapes exhibited significant isolation-by-distance and sex ratios biased towards females. The less severely fragmented landscape had larger and less isolated populations, resulting in lower levels of population genetic structure (F ST = 0.05 vs. 0.09) and inbreeding (F IS = 0.13 vs. 0.27). Genetic differentiation between host-tree subpopulations was also higher in the more fragmented landscape. We found no significant differences in within-population gene diversity, percentage of polymorphic loci, or molecular variance between the two regions, nor did we find relationships between genetic diversity measures and germination success. Our results indicate that increasing habitat fragmentation negatively affects population genetic structure and levels of inbreeding in V. album, with the degree of isolation among populations exerting a stronger influence than forest patch size. 相似文献
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Michael D. Woodrow Stuart P. Ballantine Michael D. Barker Beth J. Clarke John Dawson Tony W. Dean Christopher J. Delves Brian Evans Sharon L. Gough Steven B. Guntrip Stuart Holman Duncan S. Holmes Michael Kranz Mika K. Lindvaal Fiona S. Lucas Margarete Neu Lisa E. Ranshaw Yemisi E. Solanke Don O. Somers Peter Ward Joanne O. Wiseman 《Bioorganic & medicinal chemistry letters》2009,19(17):5261-5265
Crystallography driven optimisation of a lead derived from similarity searching of the GSK compound collection resulted in the discovery of quinoline-3-carboxamides as highly potent and selective inhibitors of phosphodiesterase 4B. This series has been optimized to GSK256066, a potent PDE4B inhibitor which also inhibits LPS induced production of TNF-α from isolated human peripheral blood mononuclear cells with a pIC50 of 11.1. GSK256066 also has a suitable profile for inhaled dosing. 相似文献
999.
Jennifer S Michaelson Stephen J Demarest Brian Miller Aldo Amatucci William B Snyder Xiufeng Wu Flora Huang Samantha Phan Sharon Gao Adam Doern Graham K Farrington Alexey Lugovskoy Ingrid Joseph Veronique Bailly Xin Wang Ellen Garber Jeff Browning Scott M Glaser 《MABS-AUSTIN》2009,1(2):128-141
Bispecific antibodies (BsAbs) represent an emerging class of biologics that achieve dual targeting with a single agent. Recombinant DNA technologies have facilitated a variety of creative bispecific designs with many promising therapeutic applications; however, practical methods for producing high quality BsAbs that have good product stability, long serum half-life, straightforward purification, and scalable production have largely been limiting. Here we describe a protein-engineering approach for producing stable, scalable tetravalent IgG-like BsAbs. The stability-engineered IgG-like BsAb was envisioned to target and crosslink two TNF family member receptors, TRAIL-R2 (TNF-Related Apoptosis Inducing Ligand Receptor-2) and LTβR (Lymphotoxin-beta Receptor), expressed on the surface of epithelial tumor cells with the goal of triggering an enhanced anti-tumor effect. Our IgG-like BsAbs consists of a stability-engineered anti-LTβR single chain Fv (scFv) genetically fused to either the N- or C-terminus of the heavy chain of a full-length anti-TRAIL-R2 IgG1 monoclonal antibody. Both N- or C-terminal BsAbs were active in inhibiting tumor cell growth in vitro, and with some cell lines demonstrated enhanced activity relative to the combination of parental Abs. Pharmacokinetic studies in mice revealed long serum half-lives for the BsAbs. In murine tumor xenograft models, therapeutic treatment with the BsAbs resulted in reduction in tumor volume either comparable to or greater than the combination of parental antibodies, indicating that simultaneously targeting and cross-linking receptor pairs is an effective strategy for treating tumor cells. These studies support that stability-engineering is an enabling step for producing scalable IgG-like BsAbs with properties desirable for biopharmaceutical development.Key words: bispecific antibodies, single-chain Fv, immunoglobulins, antibody therapeutics, protein stability, pharmacokinetics, protein engineering, tumor inhibition, cancer treatment 相似文献
1000.