Iron economy in Chlamydomonas reinhardtii.

While research on iron nutrition in plants has largely focused on iron-uptake pathways, photosynthetic microbes such as the unicellular green alga Chlamydomonas reinhardtii provide excellent experimental systems for understanding iron metabolism at the subcellular level. Several paradigms in iron homeostasis have been established in this alga, including photosystem remodeling in the chloroplast and preferential retention of some pathways and key iron-dependent proteins in response to suboptimal iron supply. This review presents our current understanding of iron homeostasis in Chlamydomonas, with specific attention on characterized responses to changes in iron supply, like iron-deficiency. An overview of frequently used methods for the investigation of iron-responsive gene expression, physiology and metabolism is also provided, including preparation of media, the effect of cell size, cell density and strain choice on quantitative measurements and methods for the determination of metal content and assessing the effect of iron supply on photosynthetic performance

Micro-RNA expression in cisplatin resistant germ cell tumor cell lines

<p>Abstract</p> <p>Background</p> <p>We compared microRNA expression patterns in three cisplatin resistant sublines derived from paternal cisplatin sensitive germ cell tumor cell lines in order to improve our understanding of the mechanisms of cisplatin resistance.</p> <p>Methods</p> <p>Three cisplatin resistant sublines (NTERA-2-R, NCCIT-R, 2102EP-R) showing 2.7-11.3-fold increase in drug resistance after intermittent exposure to increasing doses of cisplatin were compared to their parental counterparts, three well established relatively cisplatin sensitive germ cell tumor cell lines (NTERA-2, NCCIT, 2102EP). Cells were cultured and total RNA was isolated from all 6 cell lines in three independent experiments. RNA was converted into cDNA and quantitative RT-PCR was run using 384 well low density arrays covering almost all (738) known microRNA species of human origin.</p> <p>Results</p> <p>Altogether 72 of 738 (9.8%) microRNAs appeared differentially expressed between sensitive and resistant cell line pairs (NTERA-2R/NTERA-2 = 43, NCCIT-R/NCCIT = 53, 2102EP-R/2102EP = 15) of which 46.7-95.3% were up-regulated (NTERA-2R/NTERA-2 = 95.3%, NCCIT-R/NCCIT = 62.3%, 2102EP-R/2102EP = 46.7%). The number of genes showing differential expression in more than one of the cell line pairs was 34 between NTERA-2R/NTERA-2 (79%) and NCCIT-R/NCCIT (64%), and 3 and 4, respectively, between these two cell lines and 2102EP-R/2102EP (about 27%). Only the has-miR-10b involved in breast cancer invasion and metastasis and has-miR-512-3p appeared to be up-regulated (2-3-fold) in all three cell lines. The hsa-miR-371-373 cluster (counteracting cellular senescence and linked with differentiation potency), as well as hsa-miR-520c/-520h (inhibiting the tumor suppressor p21) were 3.9-16.3 fold up-regulated in two of the three cisplatin resistant cell lines. Several new micro-RNA species missing an annotation towards cisplatin resistance could be identified. These were hsa-miR-512-3p/-515/-517/-518/-525 (up to 8.1-fold up-regulated) and hsa-miR-99a/-100/-145 (up to 10-fold down-regulated).</p> <p>Conclusion</p> <p>Examining almost all known human micro-RNA species confirmed the miR-371-373 cluster as a promising target for explaining cisplatin resistance, potentially by counteracting wild-type P53 induced senescence or linking it with the potency to differentiate. Moreover, we describe for the first time an association of the up-regulation of micro-RNA species such as hsa-miR-512-3p/-515/-517/-518/-525 and down-regulation of hsa-miR-99a/-100/-145 with a cisplatin resistant phenotype in human germ cell tumors. Further functional analyses are warranted to gain insight into their role in drug resistance.</p

Index insurance and climate risk management: addressing social equity

Motivation Fair distribution of benefits from index insurance matters. Lack of attention to social equity can reinforce inequalities and undermine the potential index insurance holds as a tool for climate risk management that is also pro-poor. Purpose The aims are to: (i) examine social equity concerns raised by index insurance in the context of climate risk management; (ii) consider how greater attention can be given to social equity in index insurance initiatives; and (iii) reflect on the policy challenges raised by seeking to take social equity into account as a mechanism for climate risk reduction. Approach and methods The article draws on learning from the CGIAR’s Research Program on Climate Change, Agriculture and Food Security (CCAFS) and presents the cases of the Index Based Livelihoods Insurance (IBLI) and Agriculture and Climate Risk Enterprise Ltd. (ACRE) in East Africa. It proposes a framework for unpacking social equity related to equitable access, procedures, representation and distribution within index insurance schemes Findings Systematically addressing social equity raises hard policy choices for index insurance initiatives without straightforward solutions. Attention to how benefits and burdens of index insurance are distributed raises the unpalateable truth for development policy that the poorest members of rural society can be excluded. Nevertheless, a focus on social equity may open up opportunities to ensure index insurance is linked to more socially just climate risk management. At the very least, it may prevent index insurance from generating greater inequality. Taking social equity into account thus, shifts the focus from agricultural systems in transition per se to systems with potential to incorporate societal transformation through distributive justice. Policy implications A framework is presented for unpacking different dimensions of social equity in index insurance schemes. It is intended to facilitate identification of opportunities for building outcomes that are more equitable, with greater potential for inclusion and fairer distribution

Agricultural Recovery: Food Security and Beyond

Burundi is still experiencing a major food crisis. One important element that will help to avoid new episodes of violence is revised agricultural policies that support sustainable food security. Food crops and livestock supply 91 percent of agricultural GDP and the major livelihood for most households, thus it is essential to promote production and commercialization of subsistence crops and livestock. These subsectors currently perform poorly and foster a chronic food deficit, a condition that underlines the extreme vulnerability of the population to production-related risks. With food demand increasing at an annual rate of 3 to 6 percent, it is urgent to improve the contribution of the subsistence crops and livestock subsectors. The potential for improvement is great, and beyond the need for reforms that will benefit all sectors, improvements will require public investments to enhance productivity and better market access. Necessary changes in the short-run include fostering the use of high quality seed and fertilizer, and improving the management of small livestock. In the long run, research-extension links should be strengthened, producer organizations should be encouraged and supported, and sustainable land and water management practices should be promoted. Investments in infrastructure and market intelligence will need to meet demands generated by the development of urban centers and foster competitiveness of Burundian agricultural commodities relative to those from the region. This chapter explains the food security issue in Burundi and identifies priority actions that will help overcome the major obstacles that prevent growth and improvement of the subsistence crops and livestock subsectors

Agricultural Recovery: Food Security and Beyond

Burundi is still experiencing a major food crisis. One important element that will help to avoid new episodes of violence is revised agricultural policies that support sustainable food security. Food crops and livestock supply 91 percent of agricultural GDP and the major livelihood for most households, thus it is essential to promote production and commercialization of subsistence crops and livestock. These subsectors currently perform poorly and foster a chronic food deficit, a condition that underlines the extreme vulnerability of the population to production-related risks. With food demand increasing at an annual rate of 3 to 6 percent, it is urgent to improve the contribution of the subsistence crops and livestock subsectors. The potential for improvement is great, and beyond the need for reforms that will benefit all sectors, improvements will require public investments to enhance productivity and better market access. Necessary changes in the short-run include fostering the use of high quality seed and fertilizer, and improving the management of small livestock. In the long run, research-extension links should be strengthened, producer organizations should be encouraged and supported, and sustainable land and water management practices should be promoted. Investments in infrastructure and market intelligence will need to meet demands generated by the development of urban centers and foster competitiveness of Burundian agricultural commodities relative to those from the region. This chapter explains the food security issue in Burundi and identifies priority actions that will help overcome the major obstacles that prevent growth and improvement of the subsistence crops and livestock subsectors

Genome-based Approaches for Understanding Nutritional Iron Homeostasis in Chlamydomonas reinhardtii

Iron is an essential nutrient for all life forms, including plants, but of limiting availability in many environments, affecting productivity of both food production and carbon capturing. Iron is essential because of its broad function as a catalyst of redox reactions and processes involving O2 chemistry in the catalytic centers of enzymes. Because of the nature of these reactions, excess amounts of the nutrient can be toxic, requiring a fine tuning of the cellular iron content, to both accommodate the essential demand and avoid detrimental effects simultaneously. A question of this project is how plant metabolism is modified in iron-deficient conditions, for which the green alga Chlamydomonas reinhardtii as a microbe is an excellent reference organism. The metabolic flexibility of C. reinhardtii, specifically the capacity for both heterotrophic (on acetate) and autotrophic (on CO2) growth, offers a unique opportunity to distinguish the impact of iron nutrition on photosynthetic versus respiratory metabolism. During steady-state photoheterotrophic Fe-limited growth, where the cells are provided with light, CO2, and acetate, but lack extracellular iron, cells maintain respiration while decreasing photosynthetic contribution to the energetics of the cell. This thesis analyzes the transition from photoautotrophic (light and CO2) to photoheterotrophic cultures in the context of Fe-nutrition by adding a reduced carbon source to phototrophic cultures and assessing the developing changes to the metabolism time-dependently, in various levels of readouts. Based on the transcriptome analysis, all major cellular processes and pathways respond to the availability of acetate, but Fe-limited cells specifically sacrifice photosynthetic capacity towards respiratory activity in the first 12h after the additional carbon source becomes available, allowing to gain mechanistic insights of transitioning between different ways of life, dependent on the nutritional makeup of the environment. Secondly, exposure to high extracellular iron amounts, its opportunities, and the mechanisms of avoiding deleterious effects as a result from it, had been under-investigated before the beginning of this thesis. Physiological and photosynthetic parameters, elemental analysis, transcriptomics, and a mutant depleted of functional acidic vacuoles, proposed to be involved in the storage for transition metals, were utilized to further the understanding of the processes. Altogether, the results presented in this thesis illustrate how C. reinhardtii can be successfully used as a model organism to study a large variety of aspects of cell and molecular biology, including dynamic acclimations to changing environments

La genèse du «Louis XI» de Delavigne

Glaesener Henri. La genèse du «Louis XI» de Delavigne. In: Revue belge de philologie et d'histoire, tome 14, fasc. 2, 1935. pp. 389-403

D'Antioche à Tortose (histoire et légende)

Glaesener Henri. D'Antioche à Tortose (histoire et légende). In: Revue belge de philologie et d'histoire, tome 22, fasc. 1-2, 1943. pp. 35-58