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1. Ultrafast In vivo Transient Absorption Spectroscopy

Author

Baikie, Tomi K., Kosmützky, Darius, Lawrence, Joshua M., Gray, Victor, Schnedermann, Christoph, Horton, Robin, Collins, Joel D., Medipally, Hitesh, Witek, Bartosz, Nowaczyk, Marc M., Zhang, Jenny, Wey, Laura, Howe, Christopher J., and Rao, Akshay

Subjects
Physics - Biological Physics
Abstract

Transient absorption (TA) spectroscopy has proved fundamental to our understanding of energy and charge transfer in biological systems, allowing measurements of photoactive proteins on sub-picosecond timescales. Recently, ultrafast TA spectroscopy has been applied in vivo, providing sub-picosecond measurements of photosynthetic light harvesting and electron transfer processes within living photosynthetic microorganisms. The analysis of the resultant data is hindered by the number of different photoactive pigments and the associated complexity of photoactive reaction schemes within living cells. Here we show how in vivo ultrafast TA spectroscopy can be applied to a diverse array of organisms from the tree of life, both photosynthetic and non-photosynthetic. We have developed a series of software tools for performing global, lifetime and target analysis of in vivo TA datasets. These advances establish in vivo TA spectroscopy as a versatile technique for studying energy and charge transfer in living systems., Comment: 39 pages

Published
2023

6. Photosynthesis re-wired on the pico-second timescale

Author

Baikie, Tomi K., Wey, Laura T., Medipally, Hitesh, Reisner, Erwin, Nowaczyk, Marc M., Friend, Richard H., Howe, Christopher J., Schnedermann, Christoph, Rao, Akshay, and Zhang, Jenny Z.

Subjects
Physics - Biological Physics
Abstract

Photosystems II and I (PSII and PSI) are the reaction centre complexes that drive the light reactions of photosynthesis. PSII performs light-driven water oxidation (quantum efficiencies and catalysis rates of up to 80% and 1000 $e^{-}\text{s}^{-1}$, respectively) and PSI further photo-energises the harvested electrons (quantum efficiencies of ~100%). The impressive performance of the light harvesting components of photosynthesis has motivated extensive biological, artificial and biohybrid approaches to re-wire photosynthesis to enable higher efficiencies and new reaction pathways, such as H2 evolution or alternative CO2 fixation. To date these approaches have focussed on charge extraction at the terminal electron quinones of PSII and terminal iron-sulfur clusters of PSI. Ideally electron extraction would be possible immediately from the photoexcited reaction centres to enable the greatest thermodynamic gains. However, this was believed to be impossible because the reaction centres are buried around 4 nm within PSII and 5 nm within PSI from the cytoplasmic face. Here, we demonstrate using in vivo ultrafast transient absorption (TA) spectroscopy that it is possible to extract electrons directly from photoexcited PSI and PSII, using both live cyanobacterial cells and isolated photosystems, with the exogenous electron mediator 2,6-dichloro1,4-benzoquinone (DCBQ). We postulate that DCBQ can oxidise peripheral chlorophyll pigments participating in highly delocalised charge transfer (CT) states after initial photoexcitation. Our results open new avenues to study and re-wire photosynthesis for bioenergy and semi-artificial photosynthesis.

Published
2022
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7. Gate III

Author

Howe, Christopher

Published
2013

12. Genetic tool development in marine protists: emerging model organisms for experimental cell biology

Author

Faktorová, Drahomíra, Nisbet, R Ellen R, Fernández Robledo, José A, Casacuberta, Elena, Sudek, Lisa, Allen, Andrew E, Ares, Manuel, Aresté, Cristina, Balestreri, Cecilia, Barbrook, Adrian C, Beardslee, Patrick, Bender, Sara, Booth, David S, Bouget, François-Yves, Bowler, Chris, Breglia, Susana A, Brownlee, Colin, Burger, Gertraud, Cerutti, Heriberto, Cesaroni, Rachele, Chiurillo, Miguel A, Clemente, Thomas, Coles, Duncan B, Collier, Jackie L, Cooney, Elizabeth C, Coyne, Kathryn, Docampo, Roberto, Dupont, Christopher L, Edgcomb, Virginia, Einarsson, Elin, Elustondo, Pía A, Federici, Fernan, Freire-Beneitez, Veronica, Freyria, Nastasia J, Fukuda, Kodai, García, Paulo A, Girguis, Peter R, Gomaa, Fatma, Gornik, Sebastian G, Guo, Jian, Hampl, Vladimír, Hanawa, Yutaka, Haro-Contreras, Esteban R, Hehenberger, Elisabeth, Highfield, Andrea, Hirakawa, Yoshihisa, Hopes, Amanda, Howe, Christopher J, Hu, Ian, Ibañez, Jorge, Irwin, Nicholas AT, Ishii, Yuu, Janowicz, Natalia Ewa, Jones, Adam C, Kachale, Ambar, Fujimura-Kamada, Konomi, Kaur, Binnypreet, Kaye, Jonathan Z, Kazana, Eleanna, Keeling, Patrick J, King, Nicole, Klobutcher, Lawrence A, Lander, Noelia, Lassadi, Imen, Li, Zhuhong, Lin, Senjie, Lozano, Jean-Claude, Luan, Fulei, Maruyama, Shinichiro, Matute, Tamara, Miceli, Cristina, Minagawa, Jun, Moosburner, Mark, Najle, Sebastián R, Nanjappa, Deepak, Nimmo, Isabel C, Noble, Luke, Novák Vanclová, Anna MG, Nowacki, Mariusz, Nuñez, Isaac, Pain, Arnab, Piersanti, Angela, Pucciarelli, Sandra, Pyrih, Jan, Rest, Joshua S, Rius, Mariana, Robertson, Deborah, Ruaud, Albane, Ruiz-Trillo, Iñaki, Sigg, Monika A, Silver, Pamela A, Slamovits, Claudio H, Jason Smith, G, Sprecher, Brittany N, Stern, Rowena, Swart, Estienne C, Tsaousis, Anastasios D, Tsypin, Lev, Turkewitz, Aaron, and Turnšek, Jernej

Subjects
Genetics, Biotechnology, Life Below Water, Biodiversity, DNA, Ecosystem, Environment, Eukaryota, Green Fluorescent Proteins, Marine Biology, Models, Biological, Species Specificity, Transformation, Genetic, Biological Sciences, Technology, Medical and Health Sciences, Developmental Biology
Abstract

Diverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways.

Published
2020

13. Publisher Correction: Genetic tool development in marine protists: emerging model organisms for experimental cell biology

Author

Faktorová, Drahomíra, Nisbet, R Ellen R, Fernández Robledo, José A, Casacuberta, Elena, Sudek, Lisa, Allen, Andrew E, Ares, Manuel, Aresté, Cristina, Balestreri, Cecilia, Barbrook, Adrian C, Beardslee, Patrick, Bender, Sara, Booth, David S, Bouget, François-Yves, Bowler, Chris, Breglia, Susana A, Brownlee, Colin, Burger, Gertraud, Cerutti, Heriberto, Cesaroni, Rachele, Chiurillo, Miguel A, Clemente, Thomas, Coles, Duncan B, Collier, Jackie L, Cooney, Elizabeth C, Coyne, Kathryn, Docampo, Roberto, Dupont, Christopher L, Edgcomb, Virginia, Einarsson, Elin, Elustondo, Pía A, Federici, Fernan, Freire-Beneitez, Veronica, Freyria, Nastasia J, Fukuda, Kodai, García, Paulo A, Girguis, Peter R, Gomaa, Fatma, Gornik, Sebastian G, Guo, Jian, Hampl, Vladimír, Hanawa, Yutaka, Haro-Contreras, Esteban R, Hehenberger, Elisabeth, Highfield, Andrea, Hirakawa, Yoshihisa, Hopes, Amanda, Howe, Christopher J, Hu, Ian, Ibañez, Jorge, Irwin, Nicholas AT, Ishii, Yuu, Janowicz, Natalia Ewa, Jones, Adam C, Kachale, Ambar, Fujimura-Kamada, Konomi, Kaur, Binnypreet, Kaye, Jonathan Z, Kazana, Eleanna, Keeling, Patrick J, King, Nicole, Klobutcher, Lawrence A, Lander, Noelia, Lassadi, Imen, Li, Zhuhong, Lin, Senjie, Lozano, Jean-Claude, Luan, Fulei, Maruyama, Shinichiro, Matute, Tamara, Miceli, Cristina, Minagawa, Jun, Moosburner, Mark, Najle, Sebastián R, Nanjappa, Deepak, Nimmo, Isabel C, Noble, Luke, Novák Vanclová, Anna MG, Nowacki, Mariusz, Nuñez, Isaac, Pain, Arnab, Piersanti, Angela, Pucciarelli, Sandra, Pyrih, Jan, Rest, Joshua S, Rius, Mariana, Robertson, Deborah, Ruaud, Albane, Ruiz-Trillo, Iñaki, Sigg, Monika A, Silver, Pamela A, Slamovits, Claudio H, Jason Smith, G, Sprecher, Brittany N, Stern, Rowena, Swart, Estienne C, Tsaousis, Anastasios D, Tsypin, Lev, Turkewitz, Aaron, and Turnšek, Jernej

Subjects
Biological Sciences, Technology, Medical and Health Sciences, Developmental Biology
Abstract

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Published
2020

15. Porous translucent electrodes enhance current generation from photosynthetic biofilms

Author

Wenzel, Tobias, Haertter, Daniel, Bombelli, Paolo, Howe, Christopher J., and Steiner, Ullrich

Subjects
Quantitative Biology - Other Quantitative Biology, Physics - Applied Physics
Abstract

We tested the enhancement of electrical current generated from photosynthetically active bacteria by use of electrodes with porosity on the nano- and micrometer length-scale. For two cyanobacteria on structured indium-tin-oxide electrodes, current generation was increased by two orders of magnitude and the photo-response was substantially faster compared to non-porous anodes. These properties highlight porosity as an important design strategy for electrochemical bio-interfaces. The role of porosity on different length scales was studied systematically which revealed that the main performance enhancement was caused by the increased surface area of the electrodes. More complex microstructured architectures which spanned biofilms as translucent 3D scaffolds provided additional advantage in the presence of microbial direct electron transfer (DET). The absence of a clear DET contribution in both studied cyanobacteria, Synechocystis and Nostoc, raises questions about the role of conductive cellular components previously found in both organisms., Comment: 11 pages manuscript and 6 pages supplementary material, 18 figures overall

Published
2017
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21. A High Power-Density Mediator-Free Microfluidic Biophotovoltaic Device for Cyanobacterial Cells

Author

Bombelli, Paolo, Müller, Thomas, Herling, Therese W., Howe, Christopher J., and Knowles, Tuomas P. J.

Subjects
Physics - Biological Physics, Quantitative Biology - Other Quantitative Biology
Abstract

Biophotovoltaics has emerged as a promising technology for generating renewable energy since 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, we devise a platform to harness the large power densities afforded by miniaturised geometries. To this effect, we have developed a soft-lithography approach for the fabrication of microfluidic biophotovoltaic devices that do not require membranes or mediators. Synechocystis sp. PCC 6803 cells were injected and allowed to settle on the anode, permitting the physical proximity between cells and electrode required for mediator-free operation. We demonstrate power densities of above 100 mW/m2 for a chlorophyll concentration of 100 {\mu}M under white light, a high value for biophotovoltaic devices without extrinsic supply of additional energy., Comment: 9 pages, 7 figures, including supporting material. appears in Advanced Energy Materials, in print, 2014

Published
2014
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22. Exploiting algal NADPH oxidase for biophotovoltaic energy

Author

Anderson, Alexander, Laohavisit, Anuphon, Blaby, Ian K, Bombelli, Paolo, Howe, Christopher J, Merchant, Sabeeha S, Davies, Julia M, and Smith, Alison G

Subjects
Biological Sciences, Industrial Biotechnology, Affordable and Clean Energy, Biofuels, Chlamydomonas reinhardtii, Electricity, Extracellular Space, Genetic Complementation Test, Light, NADPH Oxidases, Plant Proteins, Superoxides, alga, biophotovoltaic, Chlamydomonas, energy, NADPH oxidase, NADPH Oxidase, Technology, Medical and Health Sciences, Biotechnology, Agricultural biotechnology, Plant biology
Abstract

Photosynthetic microbes exhibit light-dependent electron export across the cell membrane, which can generate electricity in biological photovoltaic (BPV) devices. How electrons are exported remains to be determined; the identification of mechanisms would help selection or generation of photosynthetic microbes capable of enhanced electrical output. We show that plasma membrane NADPH oxidase activity is a significant component of light-dependent generation of electricity by the unicellular green alga Chlamydomonas reinhardtii. NADPH oxidases export electrons across the plasma membrane to form superoxide anion from oxygen. The C. reinhardtii mutant lacking the NADPH oxidase encoded by RBO1 is impaired in both extracellular superoxide anion production and current generation in a BPV device. Complementation with the wild-type gene restores both capacities, demonstrating the role of the enzyme in electron export. Monitoring light-dependent extracellular superoxide production with a colorimetric assay is shown to be an effective way of screening for electrogenic potential of candidate algal strains. The results show that algal NADPH oxidases are important for superoxide anion production and open avenues for optimizing the biological component of these devices.

Published
2016

24. Classification of Physical Activity Cut-Points and the Estimation of Energy Expenditure during Walking Using the GT3X+ Accelerometer in Overweight and Obese Adults

Author

Howe, Christopher C. F., Moir, Hannah J., and Easton, Chris

Abstract

This study establishes tri-axial activity count (AC) cut-points for the GT3X+ accelerometer to classify physical activity intensity in overweight and obese adults. Further, we examined the accuracy of established and novel energy expenditure (EE) prediction equations based on AC and other metrics. "Part 1": Twenty overweight or obese adults completed a 30 minute incremental treadmill walking protocol. Heart rate (HR), EE, and AC were measured using the GT3X+ accelerometer. "Part 2": Ten overweight and obese adults conducted a self-paced external walk during which EE, AC, and HR were measured. Established equations (Freedson et al., 1998; Sasaki et al., 2011) overestimated EE by 40% and 31%, respectively (p < 0.01). Novel gender-specific prediction equations provided good estimates of EE during treadmill and outdoor walking (standard error of the estimate = 0.91 and 0.65, respectively). We propose new cut-points and prediction equations to estimate EE using the GT3X+ tri-axial accelerometer in overweight and obese adults.

Published
2017
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26. Medium-energy ions scattering studies of ultrathin metallic films on the face-centred cubic (111) surface

Author

Howe, Christopher J.

Subjects
669.9
Abstract

An experimental investigation of ultrathin metallic films on face centred cubic(111) surfaces using medium energy ion scattering as a primary experimental technique is reported. A suite of custom software written for data-processing, calibration and analysis has also been described. The specific experimental systems investigated are 0.25 ML to 3.89 ML of palladium on copper(111) and 0.23 ML to 3.74 ML of silver on aluminium(111). The Pd CU(111) system was shown to exhibit 42% twinning at 0.25 ML through 4.74 ML. At 0.25 ML coverage it has been shown that the Pd migrates into the top three layers of the substrate. The Pd was shown to be distributed 27% ± 3%, 67% ± 3% and 6% ± 3% in the 1st, 2nd and 3rd layers. The first and second interlayer spacings we also found to contract by 4% and expand by 4% respectively for the 0.25 ML coverage.

Published
2008

27. Investigating the function of the retention/retrieval, ERp57-binding and glycan-binding sites of calreticulin in MHC class I antigen presentation

Author

Howe, Christopher Mark

Subjects
571.96
Abstract

Calreticulin (CRT) is an Endoplasmic Reticulum (ER) resident protein involved in intracellular calcium homeostasis and the folding of newly synthesised glycoproteins. CRT also forms part of the peptide loading complex (PLC) where it assists in Major Histocompatibility Complex (MHC) class I folding, maturation and peptide loading with the assistance of ERp57. The CRT -/- mouse fibroblast cell line K42 loads MHC class I molecules and presents endogenous antigens to cytotoxic T lymphocytes inefficiently. Importantly, the trafficking speed of the endogenous class I alleles (H-2Kb and H-2Db) to the cell surface was shown to be faster in K42 than in its CRT +/+ counterpart K41; furthermore fewer MHC I were incorporated into the PLC in K42, similar to a class I T134K mutant that fails to present antigen efficiently. This suggests that CRT influences MHC I trafficking rate and may recruit MHC I to the PLC, ensuring efficient MHC I antigen presentation. In this study, the role of CRT was further dissected using a series of mutant constructs that were expressed in K42 and their effects on MHC I antigen presentation determined. The mutants were designed to address three questions: the role of the c-terminus and KDEL in MHC I retention / retrieval; the importance of the interaction between CRT and ERp57; and the effect of mutation of CRT's glycan-binding site on MHC I antigen presentation. Unexpectedly, the glycan-binding CRT mutant fully restored MHC I antigen presentation, suggesting that polypeptide interactions define CRT substrate specificity. However, efficient MHC I assembly with the PLC was shown to require an interaction between CRT and ERp57. The trafficking rate of MHC I was influenced not just by the KDEL sequence but also by the interaction between CRT and ERp57 and by undefined residues within the 11 c-terminal amino acids of CRT, consistent with a role in MHC I retention / retrieval. Cumulatively, the results show that the CRT's c-terminus, KDEL sequence and ERp57 binding site, but not CRT's glycan-binding site, are obligatory for efficient MHC I antigen presentation.

Published
2007

28. Cytochrome c 6A of Chloroplasts

Author

Howe, Christopher J., Nimmo, Robert H., Barbrook, Adrian C., Bendall, Derek S., Govindjee, Series editor, Sharkey, Thomas D., Series editor, Cramer, William A., editor, and Kallas, Toivo, editor

Published
2016
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31. Hydrocarbons Are Essential for Optimal Cell Size, Division, and Growth of Cyanobacteria

Author

Lea-Smith, David J., Ortiz-Suarez, Maite L., Lenn, Tchern, Nürnberg, Dennis J., Baers, Laura L., Davey, Matthew P., Parolini, Lucia, Huber, Roland G., Cotton, Charles A.R., Mastroianni, Giulia, Bombelli, Paolo, Ungerer, Petra, Stevens, Tim J., Smith, Alison G., Bond, Peter J., Mullineaux, Conrad W., and Howe, Christopher J.

Published
2016

34. Testosterone in Sport

Author

Shelley, Jake, primary, Howe, Christopher, additional, Jayne Moir, Hannah, additional, and Petróczi, Andrea, additional

Published
2019
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37. Supplementary Tables 1-3 from Sirolimus Therapy for Angiomyolipoma in Tuberous Sclerosis and Sporadic Lymphangioleiomyomatosis: A Phase 2 Trial

Author

Davies, D. Mark, primary, de Vries, Petrus J., primary, Johnson, Simon R., primary, McCartney, Deborah L., primary, Cox, Jane A., primary, Serra, Andreas L., primary, Watson, Peter C., primary, Howe, Christopher J., primary, Doyle, Tim, primary, Pointon, Kate, primary, Cross, Justin J., primary, Tattersfield, Anne E., primary, Kingswood, J. Chris, primary, and Sampson, Julian R., primary

Published
2023
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46. Biotechnological exploitation of microalgae

Author

Gangl, Doris, Zedler, Julie A. Z., Rajakumar, Priscilla D., Martinez, Erick M. Ramos, Riseley, Anthony, Włodarczyk, Artur, Purton, Saul, Sakuragi, Yumiko, Howe, Christopher J., Jensen, Poul Erik, and Robinson, Colin

Published
2015

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