45,327 research outputs found
Nannipieri, P., Ascher, J., Ceccherini, M.T., Landi, L., Pietramellara, G. & Renella, G. 2003. Microbial diversity and soil functions. European Journal of Soil Science, 54, 655–670.: Reflections by P. Nannipieri, J. Ascher-Jenull, M. T. Ceccherini, L. Giagnoni, G. Pietramellara & G. Renella
No full textOur review of 2003 discussed the meaning of both microbial diversity and microbial activity at the dawn of the ‘soil omics’ era. It focused on problems with the methods to determine them and on the main ways that soil functions depend on microbial processes. Between 2003 and 2016, the molecular techniques applied in the study of soil microbial diversity have improved markedly. Sequencing techniques today provide accurate estimates of microbial diversity in soil, whereas determining the expression of microbial genes as synthesized proteins is still problematic (Renella et al., 2014a). The assumption was and still is that with a fuller understanding of microbial diversity we might be able to control some soil functions. This is a fallacy because soil functions depend on microbial activity and not only on microbial diversity. A better understanding of the link between microbial diversity and microbial activity might be obtained by an integration of molecular and classical techniques. Sequencing techniques have confirmed the primary role of soil properties in shaping soil microbial diversity and the redundancy of species involved in soil processes such as the mineralization of organic C. Future research should improve techniques for the characterization of soil proteomics, promote the combination of classical and molecular approaches, promote hypothesis‐ more than technology‐driven research and propose molecular markers as indicators of soil quality, for example, the gene copy/gene expression or gene/enzyme activity ratios
Representation theory of the symmetric group
No full textThe representation theory of the symmetric groups is a classical topic that, since the pioneering work of Frobenius, Schur and Young, has grown into a huge body of theory, with many important connections to other areas of mathematics and physics. This self-contained book provides a detailed introduction to the subject, covering classical topics such as the Littlewood-Richardson rule and the Schur-Weyl duality. Importantly the authors also present many recent advances in the area, including Lassalle's character formulas, the theory of partition algebras, and an exhaustive exposition of the approach developed by A. M. Vershik and A. Okounkov. A wealth of examples and exercises makes this an ideal textbook for graduate students. It will also serve as a useful reference for more experienced researchers across a range of areas, including algebra, computer science, statistical mechanics and theoretical physics
Abundant transcription of a cellular gene in T cells infected with human T-cell leukemia-lymphoma virus
No full textHuman T-cell leukemia-lymphoma virus (HTLV) is a type C retrovirus associated with a subtype of mature T-cell malignancy in humans. HTLV also infects normal human cord blood mature T lymphocytes in vitro and induces a number of phenotypic changes in these cells, including their continuous growth and partial or complete independence of T-cell growth factor (TCGF). As part of our initial study designed to analyze gene(s) specifically activated by HTLV infection, we have isolated a recombinant DNA clone by differential screening of a cDNA library made from mRNA of a human T-cell lymphoma cell line producing HTLV. This cDNA identifies a single-copy gene in all human DNAs and a single mRNA species of 2.3 kilobases expressed at several hundred copies per cell in five HTLV-positive neoplastic T-cell lines. In addition, cord blood T lymphocytes infected with HTLV, but not the uninfected counterparts, express high levels of mRNA from this gene. A survey of different human hematopoietic cell types showed that this gene is expressed at low or undetectable levels (less than 10 copies) in human T, B, myeloid, or erythroid cell lines; in moderate amounts in lymphoid precursor (immature) cell lines; and in high amounts in lectin-activated mature T-cells, comparable to those of HTLV-infected T-cell lines. The precise function of this gene has not yet been determined
Soil as a biological system
No full textSoil plays a fundamental and irreplaceable role in the biosphere because it governs plant productivity of terrestrial ecosystem, allows the completion of the biogeochemical cycles and microorganisms inhabiting soil degrade, sooner or later, all organic compounds including those more recalcitrant. The main characteristics of soil are the domination of the solid phase, the presence of aqueous and gaseous phase and its capacity of reactions by surface active particles. These characteristics influence the biological processes carried out by the organisms inhabiting soil. A peculiarity of soil as a biological system is that it is a structured, heterogeneous, discontinuous system with organisms living in discrete microhabitats called "hot spots", that represents a small proportion (generally lower than 5%) of the overall available space. The chemical, physical and biological characteristics of these microhabitats differ both in time and space. To explain the capacity of soil to degrade all organic compounds the concepts of "microbial consortia", acquisition of novel degradation pathways by soil microorganisms, "extracellular enzymes" and "enzymatic combustion" were introduced
Abundant transcription of a cellular gene in T-cells infected with human T-cell leukemia-lymphoma virus.
No full textHuman T-cell leukemia-lymphoma virus (HTLV) is a type C retrovirus associated with a subtype of mature T-cell malignancy in humans. HTLV also infects normal human cord blood mature T lymphocytes in vitro and induces a number of phenotypic changes in these cells, including their continuous growth and partial or complete independence of T-cell growth factor (TCGF). As part of our initial study designed to analyze gene(s) specifically activated by HTLV infection, we have isolated a recombinant DNA clone by differential screening of a cDNA library made from mRNA of a human T-cell lymphoma cell line producing HTLV. This cDNA identifies a single-copy gene in all human DNAs and a single mRNA species of 2.3 kilobases expressed at several hundred copies per cell in five HTLV-positive neoplastic T-cell lines. In addition, cord blood T lymphocytes infected with HTLV, but not the uninfected counterparts, express high levels of mRNA from this gene. A survey of different human hematopoietic cell types showed that this gene is expressed at low or undetectable levels (less than 10 copies) in human T, B, myeloid, or erythroid cell lines; in moderate amounts in lymphoid precursor (immature) cell lines; and in high amounts in lectin-activated mature T-cells, comparable to those of HTLV-infected T-cell lines. The precise function of this gene has not yet been determined
Settling of finite-size particles in isotropically forced, homogeneous turbulence: interface-resolved simulations
No full textWe have simulated the gravity-induced settling of finite-size particles in a turbulent background flow which is forced in a statistically-stationary fashion. The simulations are accurately resolving the solid-fluid interface with the aid of an immersed boundary technique [1]. The parameters of the simulation are (apart from background turbulence) identical to those of reference [2], where particle clustering was observed at a Galileo number of 178 and a solid volume fraction of 0.005. In the present case, it is found that a relative turbulence intensity of 0.24 leads to the disappearance of the clusters; as a consequence, the increase in average particle settling velocity found in [2] also vanishes. [1] M. Uhlmann. An immersed boundary method with direct forcing for the simulation of particulate flows. J. Comput. Phys., 209(2):448–476, 2005. [2] M. Uhlmann and T. Doychev. Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion. J. Fluid Mech., 752:310–348, 2014
Efficient inhibition by Raltegravir of HIV-1 Infection in Human Primary Macrophages and in CD4+T Lymphocytes and of the cellular Apoptosis HIV-1 correlated
No full textBackground: Raltegravir (RAL) is the first integrase inhibitor approved for the treatment of
HIV-1 infection. Consistent evidences show an unusually drop of viral load in the first weeks
of treatment. The reason is still not clarified, and could be due to the effect on monocytesmacrophages
(M/M). Aim of our study is to investigate the anti-HIV-1 activity of RAL in CD4+
T Lymphocytes and in M/M, and evaluate the ability in preventing the HIV-1 related apoptosis.
Methods: CD4+ T lymphocytes and M/M were infected with R5- or X4-using HIV-1 strains in
presence of RAL and coreceptors inhibitors (AMD and Maraviroc). HIV-1 p24 production was
assessed by immunoenzymatic test. Apoptosis of T cells was evaluated by cytometry.
Quantification of viral DNA (integrated and extracromosomic forms) was performed on HIV-1
infected CD4+T lymphocytes by Real time PCR. Student T test was used for statistical
analysis.
Results: The values of EC50 and EC90 for RAL in HIV-1 Bal infected M/M were 0.3 nM and
6.9 nM respectively, comparable to values in PBMC (0.1 and 6.5 nM).
At day 6 the HIV-1 p24 Ag gag-production was negative for all the RAL (120 nM) treated
samples (p<0.001). In addition, after 3 days (and confirmed at 6 day) of HIV-1 Bal and IIIB
infection, we observed that integration inhibition by RAL led to the increase of the
extrachromosomic forms (HIV-1 IIIB 80±22%, HIV-1 Bal 100%) compared to what observed in
absence of RAL (HIV-1 IIIB 12 ±7%, HIV-1 Bal 47%) or in presence of RT-inhibitor AZT (HIV-
1 IIIB 40±38%, HIV-1 Bal 5%).
Moreover RAL strongly reduced apoptosis HIV-1 correlated in CD4+ T cells.
Discussion: These results showed that RAL strongly reduces HIV-1 production similarly in
M/M and CD4+T lymphocytes, increases the viral extrachromosomial HIV-1 DNA forms, and
prevents the HIV-1 related T cellular apoptosis
Harvested area did not increase abruptly—how advancements in satellite-based mapping led to erroneous conclusions
No full textUsing satellite-based maps, Ceccherini et al. (2020) report abruptly increasing harvested area estimates in several EU-countries beginning in 2015. They identify Finland and Sweden as countries with the largest harvest increases and the biggest potential effect on the EU’s climate policy strategy. Using more than 120,000 field reference observations to analyze the satellite-based map employed by Ceccherini et al. (2020) we found that the map’s ability to detect harvested areas abruptly increases after 2015. While the abrupt detected increase in harvest is merely an artifact, Ceccherini et al. (2020) interpret this difference as an indicator of increasing intensity in forest management and harvesting practice. In their response to comments, Ceccherini et al. (2021) revised their estimates to some degree but still used inadequate methods leading to an overestimation of harvested area in Finland and Sweden.
Ceccherini, G. et al. (2020). Abrupt increase in harvested forest area over Europe after 2015. Nature 583, 72-77.
Ceccherini, G., et al. (2021). Reply to Wernick, IK et al.; Palahí, M. et al. Nature 592(7856): E18-E23.Includes smaller additions to the text compared to version 1.
Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw
No full textMesophilic-hydrothermal (80-160 degrees C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 degrees C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. (C) 2015 Elsevier Ltd. All rights reserved
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