SummaryThiol peroxidases are conserved hydrogen peroxide scavenging and signaling molecules that contain redox-active cysteine residues. We show here that Gpx3, the major H2O2 sensor in yeast, is present in the mitochondrial intermembrane space (IMS), where it serves a compartment-specific role in oxidative metabolism. The IMS-localized Gpx3 contains an 18-amino acid N-terminally extended form encoded from a non-AUG codon. This acts as a mitochondrial targeting signal in a pathway independent of the hitherto known IMS-import pathways. Mitochondrial Gpx3 interacts with the Mia40 oxidoreductase in a redox-dependent manner and promotes efficient Mia40-dependent oxidative protein folding. We show that cells lacking Gpx3 have aberrant mitochondrial morphology, defective protein import capacity, and lower inner membrane potential, all of which can be rescued by expression of a mitochondrial-only form of Gpx3. Together, our data reveal a novel role for Gpx3 in mitochondrial redox regulation and protein homeostasis.

Magnetic particle hyperthermia (MPH) is a promising method for cancer treatment using magnetic nanoparticles (MNPs), which are subjected to an alternating magnetic field for local heating to the therapeutic range of 41−45 °C. In this window, the malignant regions (i.e., cancer cells) undergo a severe thermal shock while healthy tissues sustain this thermal regime with significantly milder side effects. Since the heating efficiency is directly associated with nanoparticle size, MNPs should acquire the appropriate size to maximize heating together with minimum toxicity. Herein, we report on facile synthetic controls to synthesize MNPs by an aqueous precipitation method, whereby tuning the pH values of the solution (9.0−13.5) results in a wide range of average MNP diameters from 16 to 76 nm. With respect to their size, the structural and magnetic properties of the MNPs are evaluated by adjusting the most important parameters, i.e. the MNP surrounding medium (water/agarose), the MNP concentration (1−4 mg mL −1 ), and the field amplitude (20−50 mT) and frequency (103, 375, 765 kHz). Consequently, the maximum heating efficiency is determined for each MNP size and set of parameters, outlining the optimum MNPs for MPH treatment. In this way, we can address the different heat generation mechanisms (Brownian, Neél, and hysteresis losses) to different sizes and separate Brownian and hysteresis losses for optimized sizes by studying the heat generation as a function of the medium viscosity. Finally, MNPs immobilized into agarose solution are studied under low-field MPH treatment to find the optimum conditions for clinical applications.

The diversity and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up in ONR7a medium at in situ temperatures of 25 °C and 14 °C for the Surface and Deep consortia, respectively, and crude oil as the sole source of carbon. The Deep consortium was additionally investigated at 25 °C to allow the direct comparison of the degradation rates to the Surface consortium. In total, ~50% of the alkanes and ~15% of the polycyclic aromatic hydrocarbons were degraded in all treatments by Day 24. Approximately ~95% of the total biodegradation by the Deep consortium took place within 6 days regardless of temperature, whereas comparable levels of degradation were reached on Day 12 by the Surface consortium. Both consortia were dominated by well-known hydrocarbon-degrading taxa. Temperature played a significant role in shaping the Deep consortia communities with Pseudomonas and Pseudoalteromonas dominating at 25 °C and Alcanivorax at 14 °C. Overall, the Deep consortium showed a higher efficiency for hydrocarbon degradation within the first week following contamination, which is critical in the case of oil spills, and thus merits further investigation for its exploitation in bioremediation technologies tailored to the Eastern Mediterranean Sea.

Hydrocarbon biodegradation rates in the deep-sea have been largely determined under atmospheric pressure, which may lead to non-representative results. In this work, we aim to study the response of deep-sea microbial communities of the Eastern Mediterranean Sea (EMS) to oil contamination at in situ environmental conditions and provide representative biodegradation rates. Seawater from a 600 to 1000 m depth was collected using a high-pressure (HP) sampling device equipped with a unidirectional check-valve, without depressurization upon retrieval. The sample was then passed into a HP-reactor via a piston pump without pressure disruption and used for a time-series oil biodegradation experiment at plume concentrations, with and without dispersant application, at 10 MPa and 14οC. The experimental results demonstrated a high capacity of indigenous microbial communities in the deep EMS for alkane degradation regardless of dispersant application (>70%), while PAHs were highly degraded when oil was dispersed (>90%) and presented very low half-lives (19.4 to 2.2 days), compared to published data. To our knowledge, this is the first emulation study of deep-sea bioremediation using undisturbed deep-sea microbial communities.

Clouds are one of the most significant factors in the climate system that strongly affect the Earth’s energy budget. Clouds reflect some of the sun's energy back into space, producing a cooling effect at the top of the atmosphere and at the same time trap the longwave radiation producing a warming effect. On average, the cooling effect is stronger than the warming effect, but accurately estimating the effects of clouds on the Earth's energy budget is still a major area of research. The cloud radiative effects (CRE), which is defined as the difference between the radiation under cloudy and cloud-free conditions, are mostly estimated from satellite observations. For accurate estimation from the ground, measurements by a combination of different instruments that provide vertical information about the optical and microphysical cloud and aerosol properties are necessary, to feed this information in radiative transfer models. During the CyCARE campaign, which was a joint initiative between the Cyprus University of Technology (CUT), Limassol and TROPOS, the Leipzig Aerosol and Cloud Remote Observations System (LACROS) operated at the CUT from October 2016 to March 2017. LACROS includes active and passive remote-sensing instruments, such as a PollyXT Raman-polarization lidar to retrieve aerosol vertical distribution, a 35-GHz cloud radar to obtain cloud microphysical properties, a disdrometer to measure precipitation, a Doppler lidar to track aerosol and cloud dynamics, and a microwave radiometer to measure water vapor and liquid water. Using the radiative transfer package LibRadtran the cloudy and clear sky shortwave and longwave radiation fluxes on the surface and the top of atmosphere were calculated during the CyCARE campaign. The aerosol and cloud profiles, along with other microphysical properties of clouds and aerosols were used as input in the radiative transfer model for the above-mentioned calculations. Subsequently, the CRE were obtained as the differences between all sky and clear sky fluxes. Since ERATOSTHENES Centre of Excellence (ERATOSTHENES CoE) is in the process to build up a permanent station named Cyprus Atmospheric Remote Sensing Observatory (CARO), the demonstrated CyCARE campaign depicts the capacity of the Centre to obtain long-term aerosol-cloud-radiation interactions in the sensitive climate area of the Eastern Mediterranean. The CARO constitutes the basic tool to improve the representation of clouds and aerosols in climate models and validate the satellite derived CREs.     Acknowledgments: “The authors acknowledge the ‘EXCELSIOR’: ERATOSTHENES: EΧcellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu). The ‘EXCELSIOR’ project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology”.