Identification of Sequences Encoding Symbiodinium minutum Mitochondrial Proteins.

The dinoflagellates are an extremely diverse group of algae closely related to the Apicomplexa and the ciliates. Much work has previously been undertaken to determine the presence of various biochemical pathways within dinoflagellate mitochondria. However, these studies were unable to identify several key transcripts including those encoding proteins involved in the pyruvate dehydrogenase complex, iron-sulfur cluster biosynthesis, and protein import. Here, we analyze the draft nuclear genome of the dinoflagellate Symbiodinium minutum, as well as RNAseq data to identify nuclear genes encoding mitochondrial proteins. The results confirm the presence of a complete tricarboxylic acid cycle in the dinoflagellates. Results also demonstrate the difficulties in using the genome sequence for the identification of genes due to the large number of introns, but show that it is highly useful for the determination of gene duplication events

Minimisation of energy consumption variance for multi-process manufacturing lines through genetic algorithm manipulation of production schedule

Typical manufacturing scheduling algorithms do not consider the energy consumption of each job, or its variance, when they generate a production schedule. This can become problematic for manufacturers when local infrastructure has limited energy distribution capabilities. In this paper, a genetic algorithm based schedule modification algorithm is presented. By referencing energy consumption models for each job, adjustments are made to the original schedule so that it produces a minimal variance in the total energy consumption in a multi-process manufacturing production line, all while operating within the constraints of the manufacturing line and individual processes. Empirical results show a significant reduction in energy consumption variance can be achieved on schedules containing multiple concurrent jobs

Integration of plastids with their hosts: Lessons learned from dinoflagellates.

After their endosymbiotic acquisition, plastids become intimately connected with the biology of their host. For example, genes essential for plastid function may be relocated from the genomes of plastids to the host nucleus, and pathways may evolve within the host to support the plastid. In this review, we consider the different degrees of integration observed in dinoflagellates and their associated plastids, which have been acquired through multiple different endosymbiotic events. Most dinoflagellate species possess plastids that contain the pigment peridinin and show extreme reduction and integration with the host biology. In some species, these plastids have been replaced through serial endosymbiosis with plastids derived from a different phylogenetic derivation, of which some have become intimately connected with the biology of the host whereas others have not. We discuss in particular the evolution of the fucoxanthin-containing dinoflagellates, which have adapted pathways retained from the ancestral peridinin plastid symbiosis for transcript processing in their current, serially acquired plastids. Finally, we consider why such a diversity of different degrees of integration between host and plastid is observed in different dinoflagellates and how dinoflagellates may thus inform our broader understanding of plastid evolution and function.This is the author accepted manuscript. The final version is available from PNAS via http://dx.doi.org/10.1073/pnas.142138011

Sigma models with non-commuting complex structures and extended supersymmetry

We discuss additional supersymmetries for N = (2, 2) supersymmetric non-linear sigma models described by left and right semichiral superfields.Comment: 11 pages. Talk presented by U.L. at "30th Winter School on Geometry and Physics" Srni, Czech Republic January 2010

Porous translucent electrodes enhance current generation from photosynthetic biofilms.

Some photosynthetically active bacteria transfer electrons across their membranes, generating electrical photocurrents in biofilms. Devices harvesting solar energy by this mechanism are currently limited by the charge transfer to the electrode. Here, we report the enhancement of bioelectrochemical photocurrent harvesting using electrodes with porosities on the nanometre and micrometre length scale. For the cyanobacteria Nostoc punctiforme and Synechocystis sp. PCC6803 on structured indium-tin-oxide electrodes, an increase in current generation by two orders of magnitude is observed compared to a non-porous electrode. In addition, the photo response is substantially faster compared to non-porous anodes. Electrodes with large enough mesopores for the cells to inhabit show only a small advantage over purely nanoporous electrode morphologies, suggesting the prevalence of a redox shuttle mechanism in the electron transfer from the bacteria to the electrode over a direct conduction mechanism. Our results highlight the importance of electrode nanoporosity in the design of electrochemical bio-interfaces

The Gauged (2,1) Heterotic Sigma-Model

The geometry of (2,1) supersymmetric sigma-models with isometry symmetries is discussed. The gauging of such symmetries in superspace is then studied. We find that the coupling to the (2,1) Yang-Mills supermultiplet can be achieved provided certain geometric conditions are satisfied. We construct the general gauged action, using an auxiliary vector to generate the full non-polynomial structure.Comment: LaTeX, 25 pages, no figures; version to appear in Nuclear Physics

Diversity of transcripts and transcript processing forms in plastids of the dinoflagellate alga Karenia mikimotoi.

Plastids produce a vast diversity of transcripts. These include mature transcripts containing coding sequences, and their processing precursors, as well as transcripts that lack direct coding functions, such as antisense transcripts. Although plastid transcriptomes have been characterised for many plant species, less is known about the transcripts produced in other plastid lineages. We characterised the transcripts produced in the fucoxanthin-containing plastids of the dinoflagellate alga Karenia mikimotoi. This plastid lineage, acquired through tertiary endosymbiosis, utilises transcript processing pathways that are very different from those found in plants and green algae, including 3' poly(U) tail addition, and extensive substitutional editing of transcript sequences. We have sequenced the plastid transcriptome of K. mikimotoi, and have detected evidence for divergent evolution of fucoxanthin plastid genomes. We have additionally characterised polycistronic and monocistronic transcripts from two plastid loci, psbD-tRNA (Met)-ycf4 and rpl36-rps13-rps11. We find evidence for a range of transcripts produced from each locus that differ in terms of editing state, 5' end cleavage position, and poly(U) tail addition. Finally, we identify antisense transcripts in K. mikimotoi, which appear to undergo different processing events from the corresponding sense transcripts. Overall, our study provides insights into the diversity of transcripts and processing intermediates found in plastid lineages across the eukaryotes.This work was supported by a BBSRC doctoral training grant [BB/F017464/1, to RGD], and a British Phycological Society summer undergraduate studentship [to GAH].This is the final version of the article. It was first available from Springer via http://dx.doi.org/10.1007/s11103-015-0408-

A High Power-Density, Mediator-Free, Microfluidic Biophotovoltaic Device for Cyanobacterial Cells.

Biophotovoltaics has emerged as a promising technology for generating renewable energy because it relies on living organisms as inexpensive, self-repairing, and readily available catalysts to produce electricity from an abundant resource: sunlight. The efficiency of biophotovoltaic cells, however, has remained significantly lower than that achievable through synthetic materials. Here, a platform is devised to harness the large power densities afforded by miniaturized geometries. To this effect, a soft-lithography approach is developed for the fabrication of microfluidic biophotovoltaic devices that do not require membranes or mediators. Synechocystis sp. PCC 6803 cells are injected and allowed to settle on the anode, permitting the physical proximity between cells and electrode required for mediator-free operation. Power densities of above 100 mW m-2 are demonstrated for a chlorophyll concentration of 100 μM under white light, which is a high value for biophotovoltaic devices without extrinsic supply of additional energy.RCUK, OtherThis is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/aenm.20140129

Cytochrome cM decreases photosynthesis under photomixotrophy in Synechocystis sp. PCC 6803

Photomixotrophy is a metabolic state that enables photosynthetic microorganisms to simultaneously perform photosynthesis and metabolism of imported organic carbon substrates. This process is complicated in cyanobacteria, since many, including Synechocystis sp. PCC 6803, conduct photosynthesis and respiration in an interlinked thylakoid membrane electron transport chain. Under photomixotrophy, the cell must therefore tightly regulate electron fluxes from photosynthetic and respiratory complexes. In this study, we demonstrate, via characterization of photosynthetic apparatus and the proteome, that photomixotrophic growth results in a gradual inhibition of QA- reoxidation in wild-type Synechocystis, which largely decreases photosynthesis over 3 d of growth. This process is circumvented by deleting the gene encoding cytochrome cM (CytM), a cryptic c-type heme protein widespread in cyanobacteria. The ΔCytM strain maintained active photosynthesis over the 3-d period, demonstrated by high photosynthetic O2 and CO2 fluxes and effective yields of PSI and PSII. Overall, this resulted in a higher growth rate compared to that of the wild type, which was maintained by accumulation of proteins involved in phosphate and metal uptake, and cofactor biosynthetic enzymes. While the exact role of CytM has not been determined, a mutant deficient in the thylakoid-localized respiratory terminal oxidases and CytM (ΔCox/Cyd/CytM) displayed a phenotype similar to that of ΔCytM under photomixotrophy. This, in combination with other physiological data, and in contrast to a previous hypothesis, suggests that CytM does not transfer electrons to these complexes. In summary, our data suggest that CytM may have a regulatory role in photomixotrophy by modulating the photosynthetic capacity of cells