A comparative study of MEA and DEA for post-combustion CO2 capture with different process configurations

This paper presented a comparative study of monoethanolamine (MEA) and diethanolamine (DEA) for post-combustion CO2 capture (PCC) process with different process configurations to study the interaction effect between solvent and process. The steady state process model of the conventional MEA-based PCC process was developed in Pro/II® and was validated with the experimental data. Then ten different process configurations were simulated for both MEA and DEA. Their performances in energy consumption were compared in terms of reboiler duty and total equivalent work. The results show that DEA generally has better thermal performances than MEA for all these ten process configurations. Seven process configurations provide 0.38%–4.61% total energy saving compared with the conventional PCC process for MEA, and other two configurations are not favourable. For DEA, except one configuration, other process configurations have 0.27%–4.50% total energy saving. This work also analyzed the sensitivities of three key parameters (amine concentration, stripper pressure and lean solvent loading) in conventional process and five process modifications to show optimization strategy

Sharp boundaries of Dpp signalling trigger local cell death required for Drosophila leg morphogenesis

Article available at http://dx.doi.org/10.1038/ncb1518Morphogens are secreted signalling molecules that govern many developmental processes1. In the Drosophila wing disc, the transforming growth factor (TGF) homologue Decapentaplegic (Dpp) forms a smooth gradient and specifies cell fate by conferring a defined value of morphogen activity. Thus, neighbouring cells have similar amounts of Dpp protein, and if a sharp discontinuity in Dpp activity is generated between these cells, Jun kinase (JNK)-dependent apoptosis is triggered to restore graded positional information2, 3. To date, it has been assumed that this apoptotic process is only activated when normal signalling is distorted. However, we now show that a similar process occurs during normal development: rupture in Dpp activity occurs during normal segmentation of the distal legs of Drosophila. This sharp boundary of Dpp signalling, independently of the absolute level of Dpp activity, induces a JNK—reaper-dependent apoptosis required for the morphogenesis of a particular structure of the leg, the joint. Our results show that Dpp could induce a developmental programme not only in a concentration dependent manner, but also by the creation of a sharp boundary of Dpp activity. Furthermore, the same process could be used either to restore a normal pattern in response to artificial disturbance or to direct a morphogenetic process.This work has been supported by grants from the Dirección General de Investigación Científica y Técnica (BMC 2002-00300), the Comunidad Autónoma de Madrid (08.1/0031/2001.1 and GR/SAL/0147/2004) and an Institutional Grant from the Fundación Ramón Areces. C.M. is a recipient of a Formación del Personal Universitario (F.P.U.) fellowship from the Ministerio de Educación y Ciencia.Peer reviewe

Hemotin, a regulator of phagocytosis encoded by a small ORF and xonserved across metazoans

Translation of hundreds of small ORFs (smORFs) of less than 100 amino acids has recently been revealed in vertebrates and Drosophila. Some of these peptides have essential and conserved cellular functions. In Drosophila, we have predicted a particular smORF class encoding ~80 aa hydrophobic peptides, which may function in membranes and cell organelles. Here, we characterise hemotin, a gene encoding an 88aa transmembrane smORF peptide localised to early endosomes in Drosophila macrophages. hemotin regulates endosomal maturation during phagocytosis by repressing the cooperation of 14-3-3ζ with specific phosphatidylinositol (PI) enzymes. hemotin mutants accumulate undigested phagocytic material inside enlarged endo-lysosomes and as a result, hemotin mutants have reduced ability to fight bacteria, and hence, have severely reduced life span and resistance to infections. We identify Stannin, a peptide involved in organometallic toxicity, as the Hemotin functional homologue in vertebrates, showing that this novel regulator of phagocytic processing is widely conserved, emphasizing the significance of smORF peptides in cell biology and disease

Classification and function of small open reading frames

Small open reading frames (smORFs) of 100 codons or fewer are usually - if arbitrarily - excluded from proteome annotations. Despite this, the genomes of many metazoans, including humans, contain millions of smORFs, some of which fulfil key physiological functions. Recently, the transcriptome of Drosophila melanogaster was shown to contain thousands of smORFs of different classes that actively undergo translation, which produces peptides of mostly unknown function. Here, we present a comprehensive analysis of smORFs in flies, mice and humans. We propose the existence of several functional classes of smORFs, ranging from inert DNA sequences to transcribed and translated cis-regulators of translation and peptides with a propensity to function as regulators of membrane-associated proteins, or as components of ancient protein complexes in the cytoplasm. We suggest that the different smORF classes could represent steps in gene, peptide and protein evolution. Our analysis introduces a distinction between different peptide-coding classes of smORFs in animal genomes, and highlights the role of model organisms for the study of small peptide biology in the context of development, physiology and human disease

Genetic Structure Among 50 Species of the Northeastern Pacific Rocky Intertidal Community

Comparing many species' population genetic patterns across the same seascape can identify species with different levels of structure, and suggest hypotheses about the processes that cause such variation for species in the same ecosystem. This comparative approach helps focus on geographic barriers and selective or demographic processes that define genetic connectivity on an ecosystem scale, the understanding of which is particularly important for large-scale management efforts. Moreover, a multispecies dataset has great statistical advantages over single-species studies, lending explanatory power in an effort to uncover the mechanisms driving population structure. Here, we analyze a 50-species dataset of Pacific nearshore invertebrates with the aim of discovering the most influential structuring factors along the Pacific coast of North America. We collected cytochrome c oxidase I (COI) mtDNA data from populations of 34 species of marine invertebrates sampled coarsely at four coastal locations in California, Oregon, and Alaska, and added published data from 16 additional species. All nine species with non-pelagic development have strong genetic structure. For the 41 species with pelagic development, 13 show significant genetic differentiation, nine of which show striking FST levels of 0.1–0.6. Finer scale geographic investigations show unexpected regional patterns of genetic change near Cape Mendocino in northern California for five of the six species tested. The region between Oregon and Alaska is a second focus of intraspecific genetic change, showing differentiation in half the species tested. Across regions, strong genetic subdivision occurs more often than expected in mid-to-high intertidal species, a result that may reflect reduced gene flow due to natural selection along coastal environmental gradients. Finally, the results highlight the importance of making primary research accessible to policymakers, as unexpected barriers to marine dispersal break the coast into separate demographic zones that may require their own management plans

Where the Lake Meets the Sea: Strong Reproductive Isolation Is Associated with Adaptive Divergence between Lake Resident and Anadromous Three-Spined Sticklebacks

Contact zones between divergent forms of the same species are often characterised by high levels of phenotypic diversity over small geographic distances. What processes are involved in generating such high phenotypic diversity? One possibility is that introgression and recombination between divergent forms in contact zones results in greater phenotypic and genetic polymorphism. Alternatively, strong reproductive isolation between forms may maintain distinct phenotypes, preventing homogenisation by gene flow. Contact zones between divergent freshwater-resident and anadromous stickleback (Gasterosteus aculeatus L.) forms are numerous and common throughout the species distribution, offering an opportunity to examine these contrasting hypotheses in greater detail. This study reports on an interesting new contact zone located in a tidally influenced lake catchment in western Ireland, characterised by high polymorphism for lateral plate phenotypes. Using neutral and QTL-linked microsatellite markers, we tested whether the high diversity observed in this contact zone arose as a result of introgression or reproductive isolation between divergent forms: we found strong support for the latter hypothesis. Three phenotypic and genetic clusters were identified, consistent with two divergent resident forms and a distinct anadromous completely plated population that migrates in and out of the system. Given the strong neutral differentiation detected between all three morphotypes (mean F-ST = 0.12), we hypothesised that divergent selection between forms maintains reproductive isolation. We found a correlation between neutral genetic and adaptive genetic differentiation that support this. While strong associations between QTL linked markers and phenotypes were also observed in this wild population, our results support the suggestion that such associations may be more complex in some Atlantic populations compared to those in the Pacific. These findings provide an important foundation for future work investigating the dynamics of gene flow and adaptive divergence in this newly discovered stickleback contact zone