Mammalian pre-mRNA 3' end processing factor CF I m 68 functions in mRNA export

Export of mRNA from the nucleus is linked to proper processing and packaging into ribonucleoprotein complexes. Although several observations indicate a coupling between mRNA 3' end formation and export, it is not known how these two processes are mechanistically connected. Here, we show that a subunit of the mammalian pre-mRNA 3' end processing complex, CF I(m)68, stimulates mRNA export. CF I(m)68 shuttles between the nucleus and the cytoplasm in a transcription-dependent manner and interacts with the mRNA export receptor NXF1/TAP. Consistent with the idea that CF I(m)68 may act as a novel adaptor for NXF1/TAP, we show that CF I(m)68 promotes the export of a reporter mRNA as well as of endogenous mRNAs, whereas silencing by RNAi results in the accumulation of mRNAs in the nucleus. Moreover, CF I(m)68 associates with 80S ribosomes but not polysomes, suggesting that it is part of the mRNP that is remodeled in the cytoplasm during the initial stages of translation. These results reveal a novel function for the pre-mRNA 3' end processing factor CF I(m)68 in mRNA export.

Climate-induced interannual variability of marine primary and export production in three global coupled climate carbon cycle models

Fully coupled climate carbon cycle models are sophisticated tools that are used to predict future climate change and its impact on the land and ocean carbon cycles. These models should be able to adequately represent natural variability, requiring model validation by observations. The present study focuses on the ocean carbon cycle component, in particular the spatial and temporal variability in net primary productivity (PP) and export production (EP) of particulate organic carbon (POC). Results from three coupled climate carbon cycle models (IPSL, MPIM, NCAR) are compared with observation-based estimates derived from satellite measurements of ocean colour and results from inverse modelling (data assimilation). Satellite observations of ocean colour have shown that temporal variability of PP on the global scale is largely dominated by the permanently stratified, low-latitude ocean (Behrenfeld et al., 2006) with stronger stratification (higher sea surface temperature; SST) being associated with negative PP anomalies. Results from all three coupled models confirm the role of the low-latitude, permanently stratified ocean for anomalies in globally integrated PP, but only one model (IPSL) also reproduces the inverse relationship between stratification (SST) and PP. An adequate representation of iron and macronutrient co-limitation of phytoplankton growth in the tropical ocean has shown to be the crucial mechanism determining the capability of the models to reproduce observed interactions between climate and PP.

The nuclear mRNA export receptor Mex67-Mtr2 of Trypanosoma brucei contains a unique and essential zinc finger motif.

Trypanosoma brucei is the causative agent of Human African Trypanosomiasis. Trypanosomes are early diverged protozoan parasites and show significant differences in their gene expression compared with higher eukaryotes. Due to a lack of individual gene promoters, large polycistronic transcripts are produced and individual mRNAs mature by trans-splicing and polyadenylation. In the absence of transcriptional control, regulation of gene expression occurs post-transcriptionally mainly by control of transcript stability and translation. Regulation of mRNA export from the nucleus to the cytoplasm might be an additional post-transcriptional event involved in gene regulation. However, our knowledge about mRNA export in trypanosomes is very limited. Although export factors of higher eukaryotes are reported to be conserved, only a few orthologues can be readily identified in the genome of T. brucei. Hence, biochemical approaches are needed to identify the export machinery of trypanosomes. Here, we report the functional characterization of the essential mRNA export factor TbMex67. TbMex67 contains a unique and essential N-terminal zinc finger motif. Furthermore, we could identify two interacting export factors namely TbMtr2 and the karyopherin TbIMP1. Our data show that the general heterodimeric export receptor Mex67-Mtr2 is conserved throughout the eukaryotic kingdom albeit exhibiting parasite-specific features.

Legal Implications of the Use of Export Taxes in Addressing Carbon Leakage: Competing Border Adjustment Measures

The prevailing uncertainties about the future of the post-Kyoto international legal framework for climate mitigation and adaptation increase the likelihood of unilateral trade interventions that aim to address climate policy concerns, as exemplified by the controversial European Union initiative to include the aviation industry in its emissions trading system. The emerging literature suggests that border carbon adjustment (BCA) measures imposed by importing countries would lead to substantial legal complications in relation to World Trade Organization law and hence to possible trade disputes. Lack of legal clarity on BCAs is exacerbated by potential counter or pre-emptive export restrictions that exporting countries might impose on carbon-intensive products. In this context, this paper investigates the interface between legal and welfare implications of competing unilateral BCA measures. It argues that carbon export taxes will be an inevitable part of the future climate change regime in the absence of a multilateral agreement. It also describes the channels through which competing BCAs may lead to trade conflicts and political complications as a result of their distributional and welfare impacts at the domestic and global levels.

Perfecting Imperfect Duties via Institutionalization

Onora O’Neill’s thesis that, in a world like ours, institutionalization is a necessary condition for the existence of typical universal welfare rights—the “institutionalization thesis” for short—has often been criticized. I believe that most of these criticisms fail to appreciate that the institutionalization thesis is based on her “classical” understanding of rights, which stresses the essential duty-implying character of rights. By and large, O’Neill’s thesis stands and falls with the classical theory of rights. My suggestion is, therefore, that what is really at issue between O’Neill and at least some of her critics is the proper understanding of the concept of a right.

Modeling Responses of Diatom Productivity and Biogenic Silica Export to Iron Enrichment in the Equatorial Pacific Ocean

Using a three-dimensional physical-biogeochemical model, we have investigated the modeled responses of diatom productivity and biogenic silica export to iron enrichment in the equatorial Pacific, and compared the model simulation with in situ (IronEx II) iron fertilization results. In the eastern equatorial Pacific, an area of 540,000 km(2) was enhanced with iron by changing the photosynthetic efficiency and silicate and nitrogen uptake kinetics of phytoplankton in the model for a period of 20 days. The vertically integrated Chl a and primary production increased by about threefold 5 days after the start of the experiment, similar to that observed in the IronEx II experiment. Diatoms contribute to the initial increase of the total phytoplankton biomass, but decrease sharply after 10 days because of mesozooplankton grazing. The modeled surface nutrients (silicate and nitrate) and TCO(2) anomaly fields, obtained from the difference between the "iron addition'' and "ambient'' (without iron) concentrations, also agreed well with the IronEx II observations. The enriched patch is tracked with an inert tracer similar to the SF6 used in the IronEx II. The modeled depth-time distribution of sinking biogenic silica (BSi) indicates that it would take more than 30 days after iron injection to detect any significant BSi export out of the euphotic zone. Sensitivity studies were performed to establish the importance of fertilized patch size, duration of fertilization, and the role of mesozooplankton grazing. A larger size of the iron patch tends to produce a broader extent and longer-lasting phytoplankton blooms. Longer duration prolongs phytoplankton growth, but higher zooplankton grazing pressure prevents significant phytoplankton biomass accumulation. With the same treatment of iron fertilization in the model, lowering mesozooplankton grazing rate generates much stronger diatom bloom, but it is terminated by Si(OH)(4) limitation after the initial rapid increase. Increasing mesozooplankton grazing rate, the diatom increase due to iron addition stays at minimum level, but small phytoplankton tend to increase. The numerical model experiments demonstrate the value of ecosystem modeling for evaluating the detailed interaction between biogeochemical cycle and iron fertilization in the equatorial Pacific.

God, the WTO – and hunger

Considering that endemic hunger is a consequence of poverty, and that food is arguably the most basic of all human needs, this book chapter shows one of the more prominent examples of rules and policy fragmentation but also one of the most blatant global governance problems. The three monotheistic religions Judaism, Christians and Islam are surprisingly unanimous about God’s prescriptions on hunger or, put theologically, on what can be said, or should be said, about the interpretations and traditions which, taken together, form the respective and differentiated traditions, identities and views of these beliefs on how to deal with poverty and hunger. A clear social ethos, in the form of global needs satisfaction, runs through both Jewish and Christian texts, and the Qur’an (Zakat). It confirms the value inversion between the world of the mighty and that of the hungry. The message is clear: because salvation is available only through the grace of God, those who have must give to those who have not. This is not charity: it is an inversion of values which can not be addressed by spending 0.7% of your GDP on ODA, and the implication of this sense of redistributive justice is that social offenders will be subject to the Last Judgement. Interestingly, these religious scriptures found their way directly into the human rights treaties adopted by the United Nations and ratified by the parliaments, as a legal base for the duty to protect, to respect and to remedy. On the other side the contradiction with international trade law is all the more flagrant, and it has a direct bearing on poverty: systematic surplus food dumping is still allowed under WTO rules, despite the declared objective ‘to establish a fair and market-oriented agricultural trading system’. A way forward would be a kind of ‘bottom up’ approach by focusing on extreme cases of food insecurity caused by food dumping, or by export restrictions where a direct effect of food insecurity in other countries can be established. Also, international financing institutions need to review their policies and lending priorities. The same goes for the bilateral investment treaties and a possible ‘public interest’ clause, at least in respect of agricultural land acquisitions in vulnerable countries. The bottom line is this: WTO rules cannot entail a right to violate other, equally binding treaty obligations when its membership as a whole claims to contribute to the Millennium Development Goals and pledges to eradicate extreme poverty and hunger.