Proliferating bloodstream-form Trypanosoma brucei use a negligible part of consumed glucose for anabolic processes

Our quantitative knowledge of carbon fluxes in the long slender bloodstream form (BSF) Trypanosoma brucei is mainly based on non-proliferating parasites, isolated from laboratory animals and kept in buffers. In this paper we present a carbon balance for exponentially growing bloodstream form trypanosomes. The cells grew with a doubling time of 5.3h, contained 46 μ mol of carbon (10(8) cells)(-1) and had a glucose consumption flux of 160 nmol min(-1) (10(8) cells)(-1). The molar ratio of pyruvate excreted versus glucose consumed was 2.1. Furthermore, analysis of the (13)C label distribution in pyruvate in (13)C-glucose incubations of exponentially growing trypanosomes showed that glucose was the sole substrate for pyruvate production. We conclude that the glucose metabolised in glycolysis was hardly, if at all, used for biosynthetic processes. Carbon flux through glycolysis in exponentially growing trypanosomes was 10 times higher than the incorporation of carbon into biomass. This biosynthetic carbon is derived from other precursors present in the nutrient rich growth medium. Furthermore, we found that the glycolytic flux was unaltered when the culture went into stationary phase, suggesting that most of the ATP produced in glycolysis is used for processes other than growth.     

Modeling study of the influences of the aromatic transitions and the local environment on the far-UV rotational strengths in TEM-1 β-lactamase

Rotational strengths in the far-UV of TEM-1 β-lactamase have been investigated with two theoretical models based on the matrix method. The first model excludes, and a second includes, effects of the local electrostatic interactions on the chromophore energies. Special attention is given to the contributions of the aromatic side-chain chromophores, and the mechanisms of generation of rotational strengths are analyzed. The sensitivity of the computational models with respect to the structural changes of the protein are discussed. Figure Structure of TEM-1 β-lactamase. Both domains—α and αβ, the secondary structural elements and the aromatic and disulfide chromophores are shown     

Putting pharmacogenetics into practice

Genetics is slowly explaining variations in drug response, but applying this knowledge depends on implementation of a host of policies that provide long-term support to the field, from translational research and regulation to professional education.     

Human diet and land use in the time of the Khans—Archaeobotanical research in the capital of the Mongolian Empire, Qara Qorum, Mongolia

Archaeobotanical investigations at Qara Qorum (Karakorum), Mongolia, reveal information about diet and land use from the 13th to the 15th century A.D. People grew Panicum miliaceum, Hordeum vulgare, Triticum aestivum and Setaria italica in nearby irrigated fields but additionally imported all other known cereals, including Oryza sativa, in small amounts as well as oil and fibre plants and pulses. The most common oil and fibre plant was Cannabis sativa. At least ten species of vegetables and spices such as Carum carvi, Coriandrum sativum, Apium graveolens, Beta vulgaris, Lycium chinense and Piper nigrum were either gathered from the wild, grown locally or imported. Apart from some wild gathered species like Pinus sibirica and Fragaria vesca, most of the fruits and nuts as for instance Vitis vinifera, Ficus carica, Ziziphus jujuba, Prunus dulcis, P. insititia, P. avium and P. persica, Cucumis melo and Juglans regia must also have been imported from quite long distances. First pollen results from lake Ugii Nuur, 50 km north of Qara Qorum indicate a much earlier beginning of agriculture than in the high and late Medieval.     

Role of EVERGREEN in the development of the cymose petunia inflorescence

Plants species diverge with regard to the time and place where they make flowers. Flowers can develop from apical meristems, lateral meristems, or both, resulting in three major inflorescence types known as racemes, cymes, and panicles, respectively. The mechanisms that determine a racemose architecture have been uncovered in Arabidopsis and Antirrhinum. To understand how cymes are specified, we studied mutations that alter the petunia inflorescence. Here we show that EVERGREEN (EVG) encodes a WOX homeodomain protein, which is exclusively expressed in incipient lateral inflorescence meristems (IMs), promoting their separation from the apical floral meristem (FM). This is essential for activation of DOUBLE TOP and specification of floral identity. Mutations that change the cymose petunia inflorescence into a solitary flower fully suppress the evg phenotype. Our data suggest a key role for EVG in the diversification of inflorescence architectures and reveal an unanticipated link between the proliferation and identity of meristems.     

Encapsulation of osteoblast seeded microcarriers into injectable, photopolymerizable three-dimensional scaffolds based on d,l-lactide and epsilon-caprolactone

UMR-106 seeded microcarriers were encapsulated into in situ, photopolymerizable three-dimensional scaffolds based on d,l-lactide and epsilon-caprolactone. UMR-106 and rat bone marrow cells proliferated and differentiated well on the microcarriers. The microcarriers were completely colonized after 14 days in culture. The viscous polymer paste allowed to mix the UMR-106 seeded microcarriers and gelatin (porosigen) properly. After the photopolymerization process, microcarriers and gelatin were evenly distributed throughout the scaffold. Gelatin was leached out within 7 h, and a porous scaffold was obtained. The microcarriers remained in the scaffold even after 7 days which demonstrates that they were well entrapped in the polymer. Increasing the amount of entrapped microcarriers (20-50%) leads to scaffolds with a reduced cross-linking. Hence, the microcarriers leached out. The encapsulated UMR-106 cells did not show pyknotic nuclei which demonstrates that the photopolymerization and handling the viscous polymer/gelatin/microcarrier paste is not detrimental for the cells.     

CIRCUMSTELLAR AND INTERSTELLAR SYNTHESIS OF ORGANIC MOLECULES

We review the formation and evolution of complex circumstellar and interstellar molecules. A number of promising chemical routes are discussed which may lead to the formation of polycyclic aromatic hydrocarbon molecules, fullerenes, and unsaturated hydrocarbon chains in the outflows from stars. Some of the problems with these chemical schemes are pointed out as well. We also review the role of grains in the formation of complex molecules in interstellar molecular clouds. This starts with the formation of simple molecules in an ice grain mantle. UV photolysis and/or thermal polymerization can convert some of these simple molecules into more complex polymeric structures. Some of these species may be released to the gas phase, particularly in the warm regions around newly formed stars. Methanol and formaldehyde seem to play an important role in this drive towards molecular complexity and their chemistry is traced in some detail.     

HLA-Dr-expressing CD8bright cells are only temporarily present in the circulation during subcutaneous recombinant interleukin-2 therapy in renal cell carcinoma patients

The effect of subcutaneous recombinant interleukin-2 (rIL-2) therapy on the activation status of peripheral blood lymphocytes (PBL) of 17 renal cell carcinoma patients was investigated in a longitudinal study. The expression of the activation markers HLA-Dr and CD25 on cytotoxic T cells, helper T cells, and natural killer (NK) cells, was analysed using two-colour flow cytometry of whole-blood samples. In addition, the ability of isolated PBL to proliferate in vitro in response to various stimuli was investigated. The absolute amounts of NK cells and HLA-DR-expressing NK cells increased continuously during the whole course of therapy. The absolute amounts of T cells and HLA-Dr-expressing T cells, however, showed an early increase only during the first 1 or 2 weeks of therapy, after which the absolute amounts of HLA-Dr-expressing T cells decreased. In particular, the absolute amount of HLA-Dr-expressing CD8bright⁺ T cells was significantly lowered in the second half of therapy. PBL collected on day 7 of therapy (post-cycle-1 PBL) showed, as compared to those collected prior to therapy (pretherapy PBL), a decreased proliferative response in vitro after stimulation with phytohaemagglutinin, concanavalin A, soluble CD3 mAb (WT32) or rIL-2. This decreased in vitro response of post-cycle-1 PBL was also reflected in a decrease in the percentage of CD8bright⁺ T cells expressing HLA-Dr in cultures with rIL-2 or CD3 mAb, in contrast to cultures of pretherapy PBL, which showed an increase of this percentage. We conclude that T cells are the predominantly stimulated subpopulation during the first 2 weeks of subcutaneous rIL-2 therapy. The significant decrease in the absolute amounts of HLA-Dr-expressing T cells in the peripheral blood during the second half of therapy may partly be explained by a decreased responsiveness to rIL-2, but a selective redistribution of HLA-Dr-expressing cells may also be involved.     

Cell-Intrinsic Control of Interneuron Migration Drives Cortical Morphogenesis

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Schistosoma mansoni does not and cannot oxidise fatty acids,but these are used for biosynthetic purposes instead

Adult schistosomes, parasitic flatworms that cause the tropical disease schistosomiasis, have always been considered to be homolactic fermenters and, in their energy metabolism, strictly dependent on carbohydrates. However, more recent studies suggested that fatty acid β-oxidation is essential for egg production by adult female Schistosoma mansoni. To address this conundrum, we performed a comprehensive study on the lipid metabolism of S. mansoni. Incubations with [¹⁴C]-labelled fatty acids demonstrated that adults, eggs and miracidia of S. mansoni did not oxidise fatty acids, as no ¹⁴CO₂ production could be detected. We then re-examined the S. mansoni genome using the genes known to be involved in fatty acid oxidation in six eukaryotic model reference species. This showed that the earlier automatically annotated genes for fatty acid oxidation were in fact incorrectly annotated. In a further analysis we could not detect any genes encoding β-oxidation enzymes, which demonstrates that S. mansoni cannot use this pathway in any of its lifecycle stages. The same was true for Schistosoma japonicum and all other schistosome species that have been sequenced. Absence of β-oxidation, however, does not imply that fatty acids from the host are not metabolised by schistosomes. Adult schistosomes can use and modify fatty acids from their host for biosynthetic purposes and incorporate those in phospholipids and neutral lipids. Female worms deposit large amounts of these lipids in the eggs they produce, which explains why interference with the lipid metabolism in females will disturb egg formation, even though fatty acid β-oxidation does not occur in schistosomes. Our analyses of S. mansoni further revealed that during the development and maturation of the miracidium inside the egg, changes in lipid composition occur which indicate that fatty acids deposited in the egg by the female worm are used for phospholipid biosynthesis required for membrane formation in the developing miracidium.