1,127 research outputs found
Critically Assessing Forms of Resistance in Music Education
In their classrooms, music educators draw upon critical pedagogy (as described by Freire, Giroux, and hooks) for the express purpose of cultivating a climate for conscientização. Conscientização, according to Paulo Freire (2006), “refers to learning to perceive social, political, and economic contradictions and to take action against the oppressive elements of reality” (p. 35). This consciousness raising is a journey teachers pursue with students, together interrogating injustices in communities and the world in order to transform the conditions that inform them. Learning to perceive social, political, and economic contradictions often leads to multiple forms of resistance in and out of music classrooms. This chapter explores the following question: What do critical forms of assessment look like in music classrooms that use critical pedagogy and embrace resistance to foster conscientization
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Altered Chromatin Occupancy of Master Regulators Underlies Evolutionary Divergence in the Transcriptional Landscape of Erythroid Differentiation
Erythropoiesis is one of the best understood examples of cellular differentiation. Morphologically, erythroid differentiation proceeds in a nearly identical fashion between humans and mice, but recent evidence has shown that networks of gene expression governing this process are divergent between species. We undertook a systematic comparative analysis of six histone modifications and four transcriptional master regulators in primary proerythroblasts and erythroid cell lines to better understand the underlying basis of these transcriptional differences. Our analyses suggest that while chromatin structure across orthologous promoters is strongly conserved, subtle differences are associated with transcriptional divergence between species. Many transcription factor (TF) occupancy sites were poorly conserved across species (∼25% for GATA1, TAL1, and NFE2) but were more conserved between proerythroblasts and cell lines derived from the same species. We found that certain cis-regulatory modules co-occupied by GATA1, TAL1, and KLF1 are under strict evolutionary constraint and localize to genes necessary for erythroid cell identity. More generally, we show that conserved TF occupancy sites are indicative of active regulatory regions and strong gene expression that is sustained during maturation. Our results suggest that evolutionary turnover of TF binding sites associates with changes in the underlying chromatin structure, driving transcriptional divergence. We provide examples of how this framework can be applied to understand epigenomic variation in specific regulatory regions, such as the β-globin gene locus. Our findings have important implications for understanding epigenomic changes that mediate variation in cellular differentiation across species, while also providing a valuable resource for studies of hematopoiesis
Crystal structure of isobutyl 4-(2-chloro-phenyl)-5-cyano-6-{(E)-[(dimethylamino)-methylidene]amino}-2-methyl-4H-pyran-3-carboxylate
The authors thank Dr Babu Varghese, Senior Scientific Officer SAIF, IIT Madras, India, for carrying out the data collection.Peer reviewedPublisher PD
Fluctuation spectrum of fluid membranes coupled to an elastic meshwork: jump of the effective surface tension at the mesh size
We identify a class of composite membranes: fluid bilayers coupled to an
elastic meshwork, that are such that the meshwork's energy is a function
\textit{not} of the real microscopic membrane area ,
but of a \textit{smoothed} membrane's area , which corresponds to the
area of the membrane coarse-grained at the mesh size . We show that the
meshwork modifies the membrane tension both below and above the scale
, inducing a tension-jump . The
predictions of our model account for the fluctuation spectrum of red blood
cells membranes coupled to their cytoskeleton. Our results indicate that the
cytoskeleton might be under extensional stress, which would provide a means to
regulate available membrane area. We also predict an observable tension jump
for membranes decorated with polymer "brushes"
cAMP-Signalling Regulates Gametocyte-Infected Erythrocyte Deformability Required for Malaria Parasite Transmission.
Blocking Plasmodium falciparum transmission to mosquitoes has been designated a strategic objective in the global agenda of malaria elimination. Transmission is ensured by gametocyte-infected erythrocytes (GIE) that sequester in the bone marrow and at maturation are released into peripheral blood from where they are taken up during a mosquito blood meal. Release into the blood circulation is accompanied by an increase in GIE deformability that allows them to pass through the spleen. Here, we used a microsphere matrix to mimic splenic filtration and investigated the role of cAMP-signalling in regulating GIE deformability. We demonstrated that mature GIE deformability is dependent on reduced cAMP-signalling and on increased phosphodiesterase expression in stage V gametocytes, and that parasite cAMP-dependent kinase activity contributes to the stiffness of immature gametocytes. Importantly, pharmacological agents that raise cAMP levels in transmissible stage V gametocytes render them less deformable and hence less likely to circulate through the spleen. Therefore, phosphodiesterase inhibitors that raise cAMP levels in P. falciparum infected erythrocytes, such as sildenafil, represent new candidate drugs to block transmission of malaria parasites
Chromosome assignment of two cloned DNA probes hybridizing predominantly to human sex chromosomes
In situ hybridization experiments were carried out with two clones, YACG 35 and 2.8, which had been selected from two genomic libraries strongly enriched for the human Y chromosome. Besides the human Y chromosome, both sequences strongly hybridized to the human X chromosome, with few minor binding sites on autosomes. In particular, on the X chromosome DNA from clone YACG 35 hybridized to the centromeric region and the distal part of the short arm (Xp2.2). On the Y chromosome, the sequence was assigned to one site situated in the border region between Yq1.1 and Yq1.2. DNA from clone 2.8 also hybridized to the centromeric region of the X and the distal part of the short arm (Xq2.2). On the Y, however, two binding sites were observed (Yp1.1 and Yq1.2). The findings indicate that sex chromosomal sequences may be localized in homologous regions (as suggested from meiotic pairing) but also at ectopic sites
Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids
In this review, we describe and analyze a mesoscale simulation method for
fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now
called multi-particle collision dynamics (MPC) or stochastic rotation dynamics
(SRD). The method consists of alternating streaming and collision steps in an
ensemble of point particles. The multi-particle collisions are performed by
grouping particles in collision cells, and mass, momentum, and energy are
locally conserved. This simulation technique captures both full hydrodynamic
interactions and thermal fluctuations. The first part of the review begins with
a description of several widely used MPC algorithms and then discusses
important features of the original SRD algorithm and frequently used
variations. Two complementary approaches for deriving the hydrodynamic
equations and evaluating the transport coefficients are reviewed. It is then
shown how MPC algorithms can be generalized to model non-ideal fluids, and
binary mixtures with a consolute point. The importance of angular-momentum
conservation for systems like phase-separated liquids with different
viscosities is discussed. The second part of the review describes a number of
recent applications of MPC algorithms to study colloid and polymer dynamics,
the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of
viscoelastic fluids
Agronomic Management of Indigenous Mycorrhizas
Many of the advantages conferred to plants by arbuscular mycorrhiza (AM) are associated to the ability of AM plants to explore a greater volume of soil through the extraradical mycelium. Sieverding (1991) estimates that for each centimetre of colonized root there is an increase of 15 cm3 on the volume of soil explored, this value can increase to 200 cm3 depending on the circumstances. Due to the enhancement of the volume of soil explored and the ability of the extraradical mycelium to absorb and translocate nutrients to the plant, one of the most obvious and important advantages resulting from mycorrhization is the uptake of nutrients. Among of which the ones that have immobilized forms in soil, such as P, assume particular significance. Besides this, many other benefits are recognized for AM plants (Gupta et al, 2000): water stress alleviation (Augé, 2004; Cho et al, 2006), protection from root pathogens (Graham, 2001), tolerance to toxic heavy metals and phytoremediation (Audet and Charest, 2006; Göhre and Paszkowski, 2006), tolerance to adverse conditions such as very high or low temperature, high salinity (Sannazzaro et al, 2006), high or low pH (Yano and Takaki, 2005) or better performance during transplantation shock (Subhan et al, 1998). The extraradical hyphae also stabilize soil aggregates by both enmeshing soil particles (Miller e Jastrow, 1992) and producing a glycoprotein, golmalin, which may act as a glue-like substance to adhere soil particles together (Wright and Upadhyaya, 1998).
Despite the ubiquous distribution of mycorrhizal fungi (Smith and Read, 2000) and only a relative specificity between host plants and fungal isolates (McGonigle and Fitter, 1990), the obligate nature of the symbiosis implies the establishment of a plant propagation system, either under greenhouse conditions or in vitro laboratory propagation. These techniques result in high inoculum production costs, which still remains a serious problem since they are not competitive with production costs of phosphorus fertilizer. Even if farmers understand the significance of sustainable agricultural systems, the reduction of phosphorus inputs by using AM fungal inocula alone cannot be justified except, perhaps, in the case of high value crops (Saioto and Marumoto, 2002). Nurseries, high income horticulture farmers and no-agricultural application such as rehabilitation of degraded or devegetated landscapes are examples of areas where the use of commercial inoculum is current. Another serious problem is quality of commercial available products concerning guarantee of phatogene free content, storage conditions, most effective application methods and what types to use. Besides the information provided by suppliers about its inoculum can be deceiving, as from the usually referred total counts, only a fraction may be effective for a particular plant or in specific soil conditions. Gianinazzi and Vosátka (2004) assume that progress should be made towards registration procedures that stimulate the development of the mycorrhizal industry.
Some on-farm inoculum production and application methods have been studied, allowing farmers to produce locally adapted isolates and generate a taxonomically diverse inoculum (Mohandas et al, 2004; Douds et al, 2005). However the inocula produced this way are not readily processed for mechanical application to the fields, being an obstacle to the utilization in large scale agriculture, especially row crops, moreover it would represent an additional mechanical operation with the corresponding economic and soil compaction costs.
It is well recognized that inoculation of AM fungi has a potential significance in not only sustainable crop production, but also environmental conservation. However, the status quo of inoculation is far from practical technology that can be widely used in the field. Together a further basic understanding of the biology and diversity of AM fungi is needed (Abbott at al, 1995; Saito and Marumoto, 2002).
Advances in ecology during the past decade have led to a much more detailed understanding of the potential negative consequences of species introductions and the potential for negative ecological consequences of invasions by mycorrhizal fungi is poorly understood. Schwartz et al, (2006) recommend that a careful assessment documenting the need for inoculation, and the likelihood of success, should be conducted prior to inoculation because inoculations are not universally beneficial.
Agricultural practices such as crop rotation, tillage, weed control and fertilizer apllication all produce changes in the chemical, physical and biological soil variables and affect the ecological niches available for occupancy by the soil biota, influencing in different ways the symbiosis performance and consequently the inoculum development, shaping changes and upset balance of native populations. The molecular biology tools developed in the latest years have been very important for our perception of these changes, ensuing awareness of management choice implications in AM development.
In this context, for extensive farming systems and regarding environmental and economic costs, the identification of agronomic management practices that allow controlled manipulation of the fungal community and capitalization of AM mutualistic effect making use of local inoculum, seem to be a wise option for mycorrhiza promotion and development of sustainable crop production
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Racial Difference in Human Platelet PAR4 Reactivity Reflects Expression of PCTP and miR-376c
Racial differences in the pathophysiology of atherothrombosis are poorly understood. We explored the function and transcriptome of platelets in healthy black (n = 70) and white (n = 84) subjects. PAR4 thrombin receptor induced platelet aggregation and calcium mobilization were significantly greater in black subjects. Numerous differentially expressed (DE) RNAs were associated with both race and PAR4 reactivity, including phosphatidylcholine transfer protein (PCTP), and platelets from blacks expressed higher levels of PC-TP protein. PC-TP inhibition or depletion blocked activation of platelets or megakaryocytic cell lines through PAR4 but not PAR1. MiR-376c levels were DE by race and PAR4 reactivity, and were inversely correlated with PCTP mRNA levels, PC-TP protein levels and PAR4 reactivity. MiR-376c regulated expression of PC-TP in human megakaryocytes. A disproportionately high number of miRNAs DE by race and PAR4 reactivity, including miR-376c, are encoded in the DLK1-DIO3 locus, and were lower in platelets from blacks. These results support PC-TP as a regulator of the racial difference in PAR4-mediated platelet activation, indicate a genomic contribution to platelet function that differs by race, and emphasize a need to consider race effects when developing anti-thrombotic drugs
AN ANTIMICROBIAL PHTHALATE DERIVATIVE FROM BACILLUS CEREUS, THE SYMBIOTIC BACTERIUM ASSOCIATED WITH A NOVEL ENTOMOPATHOGENIC NEMATODE, RHABDITIS (OSCHEIUS) SP
Objective: To isolate and identify the bioactive metabolites from the culture filtrates of a bacterium (Bacillus cereus) symbiotically associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species.Methods: The bacterium was cultured in three different media and the antimicrobial activity was determined by the well diffusion assay. The ethyl acetate extract of the cell free culture filtrate was then purified by silica gel column chromatography and thin layer chromatography. Identification of the active metabolite was done with HPLC, GC-MS and LC-MS.Results: The cell free culture filtrate of a nematode symbiotic bacterium showed both antibacterial and antifungal activities. Fermentation conditions were standardized and optimum antibacterial activity was observed in tryptic soy broth at 72 h of incubation at 30 °C. When the ethyl acetate extract was purified by silica gel column chromatography and thin layer chromatography, an active fraction was obtained which was subjected to HPLC analysis along with GC-MS and LC-MS leading to the identification of a major compound Bis (2-ethyl hexyl) phthalate. The compound was active against Gram positive bacteria Bacillus subtilis MTCC2756, Staphylococus aureus MTCC902, Gram negative bacteria Escherichia coli MTCC 2622 and fungi such as Aspergillus flavus MTCC277, Candida albicans MTCC183, Fusarium oxysporum MTCC 284, Rhizoctonia solani MTCC 4634.Conclusion: Bis (2-ethyl hexyl) phthalate was identified as one of the metabolites produced by a nematode symbiotic bacterium associated with a novel entomopathogenic nematode Rhabditis (Oscheius) species. Thus similar compounds isolated from novel entomopathogenic bacteria would pave the way for identifying new drugs for the pharmaceutical and agricultural sector.Â
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