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  • 1
    Publication Date: 2018
    Description: Abstract Soil moisture controls microbial activity and soil carbon cycling. Because microbial activity decreases as soils dry, decomposition of soil organic matter (SOM) is thought to decrease with increasing drought length. Yet, microbial biomass and a pool of water‐extractable organic carbon (WEOC) can increase as soils dry, perhaps implying microbes may continue to break down SOM even if drought stressed. Here, we test the hypothesis that WEOC increases as soils dry because exoenzymes continue to break down litter, while their products accumulate because they cannot diffuse to microbes. To test this hypothesis, we manipulated field plots by cutting off litter inputs and by irrigating and excluding precipitation inputs to extend or shorten the length of the dry season. We expected that the longer the soils would remain dry, the more WEOC would accumulate in the presence of litter, whereas shortening the length of the dry season, or cutting off litter inputs, would reduce WEOC accumulation. Lastly, we incubated grass roots in the laboratory and measured the concentration of reducing sugars and potential hydrolytic enzyme activities, strictly to understand the mechanisms whereby exoenzymes break down litter over the dry season. As expected, extending dry season length increased WEOC concentrations by 30% above the 108 μg C/g measured in untreated plots, whereas keeping soils moist prevented WEOC from accumulating. Contrary to our hypothesis, excluding plant litter inputs actually increased WEOC concentrations by 40% above the 105 μg C/g measured in plots with plants. Reducing sugars did not accumulate in dry senesced roots in our laboratory incubation. Potential rates of reducing sugar production by hydrolytic enzymes ranged from 0.7 to 10 μmol·g−1·h−1 and far exceeded the rates of reducing sugar accumulation (~0.001 μmol·g−1·h−1). Our observations do not support the hypothesis that exoenzymes continue to break down litter to produce WEOC in dry soils. Instead, we develop the argument that physical processes are more likely to govern short‐term WEOC dynamics via slaking of microaggregates that stabilize SOM and through WEOC redistribution when soils wet up, as well as through less understood effects of drought on the soil mineral matrix.
    Print ISSN: 0012-9658
    Electronic ISSN: 1939-9170
    Topics: Biology
    Published by Wiley on behalf of The Ecological Society of America (ESA).
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  • 2
    Publication Date: 2012-09-12
    Description: Prostate cancer is the second leading cause of cancer death among United States men. However, disease aggressiveness is varied, with low-grade disease often being indolent and high-grade cancer accounting for the greatest density of deaths. Outcomes are also disparate among men with high-grade prostate cancer, with upwards of 65% having...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    Publication Date: 2011-04-14
    Description: Changes in the rates of nitrogen (N) cycling, microbial carbon (C) substrate use, and extracellular enzyme activities in a Mojave Desert ecosystem exposed to elevated atmospheric CO2 suggest shifts in the size and/or functional characteristics of microbial assemblages in two dominant soil microsites: plant interspaces and under the dominant shrub Larrea tridentata. We used ester-linked phospholipid fatty acid (PLFA) biomarkers as a proxy for microbial biomass to quantify spatial and temporal differences in soil microbial communities from February 2003 to May 2005. Further, we used the 13C signature of the fossil CO2 source for elevated CO2 plots to trace recent plant C inputs into soil organic matter (SOM) and broad microbial groups using δ13C (‰). Differences between individual δ13CPLFA and δ13CSOM for fungal biomarkers indicated active metabolism of newer C in elevated CO2 soils. Total PLFA-C was greater in shrub microsites compared to plant interspaces, and CO2 treatment differences within microsites increased under higher soil water availability. Total, fungal, and bacterial PLFA-C increased with decreasing soil volumetric water content (VWC) in both microsites, suggesting general adaptations to xeric desert conditions. Increases in fungal-to-bacterial PLFA-C ratio with decreasing VWC reflected functional group-specific responses to changing soil water availability. While temporal and spatial extremes in resource availability in desert ecosystems contribute to the difficulty in identifying common trends or mechanisms driving microbial responses in less extreme environments, we found that soil water availability and soil microsite interacted with elevated CO2 to shift fungal and bacterial biomarker abundances in Mojave Desert soils.
    Print ISSN: 0148-0227
    Topics: Biology , Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 4
    Publication Date: 2014-09-30
    Description: Nature Geoscience 7, 709 (2014). doi:10.1038/ngeo2248 Authors: P. Friedlingstein, R. M. Andrew, J. Rogelj, G. P. Peters, J. G. Canadell, R. Knutti, G. Luderer, M. R. Raupach, M. Schaeffer, D. P. van Vuuren & C. Le Quéré
    Print ISSN: 1752-0894
    Electronic ISSN: 1752-0908
    Topics: Geosciences
    Published by Springer Nature
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  • 5
    Publication Date: 2012-10-10
    Description: Assessing the ecological importance of clouds has substantial implications for our basic understanding of ecosystems and for predicting how they will respond to a changing climate. This study was conducted in a coastal Bishop pine forest ecosystem that experiences regular cycles of stratus cloud cover and inundation in summer. Our objective was to understand how these clouds impact ecosystem metabolism by contrasting two sites along a gradient of summer stratus cover. The site that was under cloud cover ~15% more of the summer daytime hours had lower air temperatures and evaporation rates, higher soil moisture content, and received more frequent fog drip inputs than the site with less cloud cover. These cloud-driven differences in environmental conditions translated into large differences in plant and microbial activity. Pine trees at the site with greater cloud cover exhibited less water stress in summer, larger basal area growth , and greater rates of sap velocity. The difference in basal area growth between the two sites was largely due to summer growth. Microbial metabolism was highly responsive to fog drip, illustrated by an observed ~3-fold increase in microbial biomass C with increasing summer fog drip. In addition, the site with more cloud cover had greater total soil respiration, and a larger fractional contribution from heterotrophic sources. We conclude that clouds are important to the ecological functioning of these coastal forests, providing summer shading and cooling that relieve pine and microbial drought stress as well as regular moisture inputs that elevate plant and microbial metabolism. These findings are important for understanding how these and other seasonally dry coastal ecosystems will respond to predicted changes in stratus cover, rainfall, and temperature. © 2012 Blackwell Publishing Ltd
    Print ISSN: 1354-1013
    Electronic ISSN: 1365-2486
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Published by Wiley
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  • 6
    Publication Date: 2019
    Description: Abstract The delivery of fermentable substrate(s) to subsurface environments stimulates Fe(III)‐bioreduction and achieves detoxification of organic/inorganic contaminants. Though much research has been conducted on the microbiology of such engineered systems at lab and field scales, little attention has been given to the phage‐host interactions and virus community dynamics in these environments. The objective was to determine the responses of soil bacterial communities and viral assemblages to stimulated anaerobic Fe(III)‐bioreduction following electron donor (e.g., acetate) addition. Microbial communities, including viral assemblages, were investigated after 60 days of Fe(III)‐bioreduction in laboratory‐scale columns continuously fed with acetate‐amended artificial groundwater. Viral abundances were greatest in the influent section and decreased along the flow path. Acetate availability was important in influencing bacterial diversity, microbial interactions, and viral abundance and community composition. The impact of acetate addition was most evident in the influent section of the columns. The increased relative abundance of Fe(III)‐reducing bacteria coincided with an increase in viral abundance in areas of the columns exhibiting the most Fe(III) reduction. The genetic composition of viruses in these column sections also differed from the control column and distal sections of acetate‐treated columns suggesting viral communities responded to biostimulated Fe(III)‐bioreduction. This article is protected by copyright. All rights reserved.
    Print ISSN: 1462-2912
    Electronic ISSN: 1462-2920
    Topics: Biology
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  • 7
    Publication Date: 1999-04-24
    Description: T cell receptor (TCR) signaling requires activation of Zap-70 and Src family tyrosine kinases, but requirements for other tyrosine kinases are less clear. Combined deletion in mice of two Tec kinases, Rlk and Itk, caused marked defects in TCR responses including proliferation, cytokine production, and apoptosis in vitro and adaptive immune responses to Toxoplasma gondii in vivo. Molecular events immediately downstream from the TCR were intact in rlk-/-itk-/- cells, but intermediate events including inositol trisphosphate production, calcium mobilization, and mitogen-activated protein kinase activation were impaired, establishing Tec kinases as critical regulators of TCR signaling required for phospholipase C-gamma activation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schaeffer, E M -- Debnath, J -- Yap, G -- McVicar, D -- Liao, X C -- Littman, D R -- Sher, A -- Varmus, H E -- Lenardo, M J -- Schwartzberg, P L -- New York, N.Y. -- Science. 1999 Apr 23;284(5414):638-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Human Genome Research Institute, National Cancer Institute, National Institute for Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10213685" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Apoptosis ; CD4-CD8 Ratio ; Calcium Signaling ; Calcium-Calmodulin-Dependent Protein Kinases/metabolism ; Diglycerides/metabolism ; Gene Targeting ; Inositol Phosphates/metabolism ; Interferon-gamma/biosynthesis ; Interleukin-2/biosynthesis/pharmacology ; Isoenzymes/metabolism ; Killer Cells, Natural/immunology ; Lymphocyte Activation ; Mice ; Mutation ; Phospholipase C gamma ; Phosphorylation ; Protein-Tyrosine Kinases/genetics/*metabolism ; Receptors, Antigen, T-Cell/*metabolism ; *Signal Transduction ; T-Lymphocytes/*enzymology/*immunology ; Toxoplasmosis, Animal/immunology ; Type C Phospholipases/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2008-09-05
    Description: 〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819144/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819144/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Howe, Doug -- Costanzo, Maria -- Fey, Petra -- Gojobori, Takashi -- Hannick, Linda -- Hide, Winston -- Hill, David P -- Kania, Renate -- Schaeffer, Mary -- St Pierre, Susan -- Twigger, Simon -- White, Owen -- Rhee, Seung Yon -- P41 HG002659/HG/NHGRI NIH HHS/ -- P41 HG002659-07/HG/NHGRI NIH HHS/ -- England -- Nature. 2008 Sep 4;455(7209):47-50. doi: 10.1038/455047a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Zebrafish Information Network, 5291 University of Oregon, Eugene, Oregon 97403-5291, USA. dhowe@cs.uoregon.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18769432" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Science Disciplines/*methods/*trends ; Career Choice ; Computational Biology/education/methods/*trends ; Databases, Factual/*trends/utilization ; Education, Graduate ; Humans ; Information Storage and Retrieval/methods/*trends ; Internet/*trends/utilization ; Publishing/trends
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 1997-06-13
    Description: Retinal neovascularization is the major cause of untreatable blindness. The role of growth hormone (GH) in ischemia-associated retinal neovascularization was studied in transgenic mice expressing a GH antagonist gene and in normal mice given an inhibitor of GH secretion (MK678). Retinal neovascularization was inhibited in these mice in inverse proportion to serum levels of GH and a downstream effector, insulin-like growth factor-I (IGF-I). Inhibition was reversed with exogenous IGF-I administration. GH inhibition did not diminish hypoxia-stimulated retinal vascular endothelial growth factor (VEGF) or VEGF receptor expression. These data suggest that systemic inhibition of GH or IGF-I, or both, may have therapeutic potential in preventing some forms of retinopathy.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, L E -- Kopchick, J J -- Chen, W -- Knapp, J -- Kinose, F -- Daley, D -- Foley, E -- Smith, R G -- Schaeffer, J M -- EY08670/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1997 Jun 13;276(5319):1706-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ophthalmology, Harvard Medical School and Children's Hospital, Boston, MA 02115, USA. smith_lo@a1.tch.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9180082" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Endothelial Growth Factors/genetics/metabolism ; Growth Hormone/agonists/antagonists & inhibitors/blood/pharmacology/*physiology ; Hormone Antagonists/pharmacology ; Insulin-Like Growth Factor I/metabolism/pharmacology ; Ischemia ; Lymphokines/genetics/metabolism ; Mice ; Mice, Inbred C57BL ; Mice, Transgenic ; Peptides, Cyclic/pharmacology ; Recombinant Proteins/pharmacology ; Retinal Neovascularization/*etiology/metabolism/pathology ; Retinal Vessels ; Vascular Endothelial Growth Factor A ; Vascular Endothelial Growth Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 1998-10-23
    Description: Nonpeptide agonists of each of the five somatostatin receptors were identified in combinatorial libraries constructed on the basis of molecular modeling of known peptide agonists. In vitro experiments using these selective compounds demonstrated the role of the somatostatin subtype-2 receptor in inhibition of glucagon release from mouse pancreatic alpha cells and the somatostatin subtype-5 receptor as a mediator of insulin secretion from pancreatic beta cells. Both receptors regulated growth hormone release from the rat anterior pituitary gland. The availability of high-affinity, subtype-selective agonists for each of the somatostatin receptors provides a direct approach to defining their physiological functions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rohrer, S P -- Birzin, E T -- Mosley, R T -- Berk, S C -- Hutchins, S M -- Shen, D M -- Xiong, Y -- Hayes, E C -- Parmar, R M -- Foor, F -- Mitra, S W -- Degrado, S J -- Shu, M -- Klopp, J M -- Cai, S J -- Blake, A -- Chan, W W -- Pasternak, A -- Yang, L -- Patchett, A A -- Smith, R G -- Chapman, K T -- Schaeffer, J M -- New York, N.Y. -- Science. 1998 Oct 23;282(5389):737-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell Biochemistry and Physiology, Merck Research Laboratories, Post Office Box 2000, Rahway, NJ 07065, USA. susanvrohrer@merck.com〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9784130" target="_blank"〉PubMed〈/a〉
    Keywords: Amides/metabolism/*pharmacology ; Amino Acid Sequence ; Animals ; Cell Line ; Cells, Cultured ; Cricetinae ; Drug Design ; Glucagon/secretion ; Growth Hormone/secretion ; Insulin/secretion ; Islets of Langerhans/drug effects/secretion ; Ligands ; Membrane Proteins ; Mice ; Models, Chemical ; Molecular Sequence Data ; Pituitary Gland, Anterior/drug effects/metabolism ; Rats ; Receptors, Somatostatin/*agonists/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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