The photosynthetic electron transport chain of oxygenic photosynthesis

Oxygenic photosynthesis, performed by plants, algae, and cyanobacteria, is the major route by which solar energy is converted into chemical energy on earth. This process provides the essentials (e.g., food and fuels) for humans to survive and is responsible for oxygenating the earth's atmosphere, which allowed the evolution of multicellular life. Photon energy is harvested during the so-called “light reactions” and used to extract electrons from water, which are then transported through an electron transport chain—in a type of bioelectric current—that is coupled to the movement of protons across the thylakoid membrane, storing energy in the form of a proton electrochemical gradient. The net result of the light reactions is the synthesis of adenosine triphosphate and reduced nicotinamide adenine dinucleotide phosphate, which are used by the “dark” or “light-independent” reactions to convert carbon dioxide into carbohydrates in the Calvin–Benson cycle. In this study, we summarize the structure and function of the main redox-active proteins involved in electron transfer and highlight some recent developments aiming to enhance the efficiency and robustness of the light reactions

Seven years of marine environmental changes monitoring at coastal OOCS stations (Catalan Sea, NW Mediterranean)

Since March 2009 up to the present (more than 7 years now), the Operational Observatory of the Catalan Sea (OOCS; http://www2.ceab.csic.es/ oceans/) remains a witness of persistent marine environmental changes. The OOCS has two fixed observation stations at the head of the Blanes Canyon (200 m depth, 41.66°N; 2.91°E) and at the Blanes bay (20 m depth, 41.67°N; 2.80°E) in the Catalan Sea, NW Mediterranean. At the canyon station, a multi-parametric buoy presently installed delivers high frequency (by 30 min) and multi-parametric oceanographic (i.e. salinity, temperature, chlorophyll, turbidity, as well as light intensity in the PAR range for the upper 50 m depth) and atmospheric (air temperature, relative humidity, wind speed and direction and PAR) data. Subsurface photos and videos by an IP high resolution fisheye camera attached to the buoy are also delivered at 4-hour basis. Data and multimedia are transmitted in near real time for public access, via combined GSM/GPRS and 3G connections. At both stations, CTD profiles and water samples (collected for nutrients and picoplankton analyses) are carried out on board a research vessel at fortnightly basis. Numerical simulations along with the time series of in-situ observations show inter-annual seasonality anomalies possibly linked to global environmental changes. The lower-atmosphere and upper-sea environmental time series data collected prove the occurrence of shifting patterns of heat and matter fluxes impacting pelagic and benthic organisms.Peer Reviewe

Association of Psb28 and Psb27 proteins with PSII-PSI supercomplexes upon exposure of Synechocystis sp. PCC 6803 to high light

Formation of the multi-subunit oxygen-evolving Photosystem II (PSII) complex involves a number of auxiliary protein factors. In this study we compared the location and possible function of two homologous PSII assembly factors, Psb28-1 and Psb28-2, from the cyanobacterium Synechocystis sp. PCC 6803. We show that FLAG-tagged Psb28-2 is present in both the monomeric PSII core complex and a PSII core complex lacking the inner antenna CP43 (RC47) whereas Psb28-1 preferentially binds to RC47. When cells are exposed to increased irradiance, both tagged Psb28 proteins now associate with oligomeric forms of PSII and with PSII-PSI supercomplexes composed of trimeric Photosystem I (PSI) and two PSII monomers as deduced from negative stain electron microscopy. The presence of the Psb27 accessory protein in these complexes suggests the involvement of PSI in PSII biogenesis, possibly by photoprotecting PSII through energy spillover. Under standard cultivation conditions the distribution of PSII complexes is similar in WT and each of the single psb28 null mutants except for loss of RC47 in the absence of Psb28-1. In comparison with WT, growth of mutants lacking Psb28-1 and Psb27, but not Psb28-2, was retarded under high-light and, especially, intermittent highlight-dark conditions, emphasizing the physiological importance of PSII assembly factors for light acclimation

Adolescent brain cognitive development (ABCD) study: Overview of substance use assessment methods.

One of the objectives of the Adolescent Brain Cognitive Development (ABCD) Study (https://abcdstudy.org/) is to establish a national longitudinal cohort of 9 and 10 year olds that will be followed for 10 years in order to prospectively study the risk and protective factors influencing substance use and its consequences, examine the impact of substance use on neurocognitive, health and psychosocial outcomes, and to understand the relationship between substance use and psychopathology. This article provides an overview of the ABCD Study Substance Use Workgroup, provides the goals for the workgroup, rationale for the substance use battery, and includes details on the substance use module methods and measurement tools used during baseline, 6-month and 1-year follow-up assessment time-points. Prospective, longitudinal assessment of these substance use domains over a period of ten years in a nationwide sample of youth presents an unprecedented opportunity to further understand the timing and interactive relationships between substance use and neurocognitive, health, and psychopathology outcomes in youth living in the United States

Ethyl cyanide on Titan: Spectroscopic detection and mapping using ALMA

We report the first spectroscopic detection of ethyl cyanide (C$_2$H$_5$CN) in Titan's atmosphere, obtained using spectrally and spatially resolved observations of multiple emission lines with the Atacama Large Millimeter/submillimeter array (ALMA). The presence of C$_2$H$_5$CN in Titan's ionosphere was previously inferred from Cassini ion mass spectrometry measurements of C$_2$H$_5$CNH$^+$. Here we report the detection of 27 rotational lines from C$_2$H$_5$CN (in 19 separate emission features detected at $>3\sigma$ confidence), in the frequency range 222-241 GHz. Simultaneous detections of multiple emission lines from HC$_3$N, CH$_3$CN and CH$_3$CCH were also obtained. In contrast to HC$_3$N, CH$_3$CN and CH$_3$CCH, which peak in Titan's northern (spring) hemisphere, the emission from C$_2$H$_5$CN is found to be concentrated in the southern (autumn) hemisphere, suggesting a distinctly different chemistry for this species, consistent with a relatively short chemical lifetime for C$_2$H$_5$CN. Radiative transfer models show that most of the C$_2$H$_5$CN is concentrated at altitudes 300-600 km, suggesting production predominantly in the mesosphere and above. Vertical column densities are found to be in the range (2-5)$\times10^{14}$ cm$^{-2}$.Comment: Published in 2015, ApJL, 800, L1

Open Space – a collaborative process for facilitating Tourism IT partnerships

The success of IT projects depends on the success of the partnerships on which they are based. However past research by the author has identified a significant rate of failure in these partnerships, predominantly due to an overly technical mindset, leading to the question: “how do we ensure that, as technological solutions are implemented within tourism, due consideration is given to human-centred issues?” The tourism partnership literature is explored for additional insights revealing that issues connected with power, participation and normative positions play a major role. The method, Open Space, is investigated for its ability to engage stakeholders in free and open debate. This paper reports on a one-day Open Space event sponsored by two major intermediaries in the UK travel industry who wanted to consult their business partners. Both the running of the event and its results reveal how Open Space has the potential to address some of the weaknesses associated with tourism partnerships

Chlorophyll f synthesis by a super-rogue photosystem II complex

Certain cyanobacteria synthesize chlorophyll molecules (Chl d and Chl f) that absorb in the far-red region of the solar spectrum, thereby extending the spectral range of photosynthetically active radiation1,2. The synthesis and introduction of these far-red chlorophylls into the photosynthetic apparatus of plants might improve the efficiency of oxygenic photosynthesis, especially in far-red enriched environments, such as in the lower regions of the canopy3. Production of Chl f requires the ChlF subunit, also known as PsbA4 (ref. 4) or super-rogue D1 (ref. 5), a paralogue of the D1 subunit of photosystem II (PSII) which, together with D2, bind cofactors involved in the light-driven oxidation of water. Current ideas suggest that ChlF oxidizes Chl a to Chl f in a homodimeric ChlF reaction centre (RC) complex and represents a missing link in the evolution of the heterodimeric D1/D2 RC of PSII (refs. 4,6). However, unambiguous biochemical support for this proposal is lacking. Here, we show that ChlF can substitute for D1 to form modified PSII complexes capable of producing Chl f. Remarkably, mutation of just two residues in D1 converts oxygen-evolving PSII into a Chl f synthase. Overall, we have identified a new class of PSII complex, which we term ‘super-rogue’ PSII, with an unexpected role in pigment biosynthesis rather than water oxidation

Effects of Naltrexone on Alcohol and Nicotine Use in Female P Rats

The objective of the present study was to determine the effectiveness of the opioid antagonist naltrexone at reducing the consumption of EtOH and nicotine in female alcohol-preferring (P) rats. P rats have been selectively bred to have a genetic predisposition for alcohol abuse, which allows them to be used as an animal model of alcoholism. P rats readily self-administer i.v nicotine (Le et al., 2016), have EtOH consumption during adolescence that is similar to that seen in adulthood, and operantly respond for EtOH until they are impaired/intoxicated (Bell et al., 2006). Thus, P rats are a useful model for studying naltrexone’s effects on EtOH and nicotine co-use

"Stopping before you start" : reducing and preventing initiation of tobacco use in the ACT

Tobacco is the leading cause of preventable death in Australia and contributes to 5.4% of disease burden in the Australian Capital Territory. Initiation of tobacco use is most likely to occur during adolescence and young adulthood (at less than 20 years). Prevention of tobacco initiation involves a combination of regulatory, educational and health promotion interventions including restrictions on the sale of tobacco products. This paper reports on the development and use of an agent-based model to explore the impact of modifying three hypothetical regulatory and health promotion interventions: 1) increasing the minimum purchasing age for tobacco products, 2) reducing retail sales of tobacco products to persons under the minimum purchasing age and 3) reducing secondary sharing of tobacco products to persons under the minimum purchasing age using health promotion messaging. The model was built using a participatory approach that engaged policy officers, health promotion officers, epidemiologists, biostatisticians and computer scientists. The structure of the model included interacting state chart representations of smoking and level of concern about tobacco use (engagement status) and a pro-smoking score, which defined the hazard rate of initiation, cessation, and relapse. The pro-smoking score was a function of several risk factors including engagement, social effect of having more or fewer smoking peers, addiction and withdrawal levels and access to tobacco products. Parameterisation of the model drew on a range of data sources with local data being prioritised where it was available. A series of scenarios comparing the impact of the interventions on smoking prevalence rates and age of initiation are reported. Of the three interventions simulated, increasing the minimum purchasing age from 18 to 21 years had the greatest impact on smoking prevalence across the population, reducing the prevalence of smoking from 8.5% (95% CI 7.8, 9.2) to 6.9% (95% CI 6.4, 7.4) five years post-intervention and 4.1% (95% CI 3.8, 4.3) 20 years post intervention (Figure 1). The interventions aimed to reduce the sale of tobacco products to minors and reduce secondary sharing produced small reductions on their own. However, when implemented in combination with increasing the minimum purchasing age, they significantly increased the impact of this intervention from ten years post-implementation, ultimately resulting in a prevalence rate of 2.8% (95% CI 2.6, 3.0) 20 years post-implementation. Given the challenges associated with ceasing tobacco use, these in silico experiments demonstrate the importance of regulatory public health interventions to delay, and therefore potentially prevent initiation