Evidence of a role for copper in iron uptake for magnetosome synthesis in the marine, magnetotactic bacterium, strain MV-1

The research in this dissertation represents the initial characterization in regards to iron uptake in the marine magnetotactic bacterium, strain MV-1. Cellular iron content differences between MV-1 and a non-magnetotactic mutant, designated MV-1nm1, suggested that MV-1nm1 is deficient in one or more iron acquisition systems present in MV-1. Protein profiles of MV-1 and MV-1nm1 showed the non-magnetotatic mutant did not produce several proteins observed in MV-1, including an iron regulated, periplasmic protein. This protein was designated p19 and is a homodimer with a subunit molecular mass of about 19,000 Da that binds copper in a 1:1 ratio. The structural gene for p19 as well as two putative upstream genes were cloned and sequenced. One of these genes encoded for a putative iron permease with similarities to Ftr1p from the yeast Saccharomyces cerevisiae, while the second encoded for a ferrodoxin-like protein of unknown function. Based on the model for a copper-dependent, high-affinity iron uptake in S. cerevisiae, the presence of a periplasmic, p19 dependent, iron oxidase was predicted to be present in MV-1. A periplasmic enzyme exhibiting this activity was subsequently identified and purified. Like Fet3p, the S. cerevisiae iron oxidase, this enzyme was iron-regulated and contained 4 atoms of copper per molecule. Though no function has been found for p19, all three components (p19, iron oxidase, iron permease) for a high-affinity iron transport system similar to that found in S. cerevisiae are present in MV-1 and may be important in providing iron for magnetosome biomineralization.;The magnetotactic bacterium strain MV-1 has been shown to grow microaerobically with sulfide or thiosulfate as electron donors and anaerobically with nitrous oxide (N2O) serving as the terminal electron acceptor. This magnetotactic strain is capable of growing autotrophically with HCO3- /CO2 supplied as the sole source of carbon in the growth media, utilizing the Calvin-Benson-Bassham pathway for CO2 fixation. Specifically, MV-1 possesses the form II RubisCO gene (cbbM). In this dissertation, the cloning and sequencing of a form II RubisCO gene (cbbM) in the magnetotactic spirillum, Magnetospirillum magnetotacticum is reported. Assessment of the magnetotactic spirilla M. gryphiswaldense and M. magneticum for the presence of cbbM was also performed

Simulation-Based Safety Training for Plant Maintenance in Virtual Reality

This paper presents a 3-D simulation model for safety training in an interactive and fully immersive virtual environment (IVE). The training comprises application of serious games (SGs) designed for filter replacements on a gas-powered plant (GPP) engine model by participants based on plant maintenance health and safety environment (HSE) regulations. Although maintenance work on GPP constitutes significantly in the share of hazards in the industry, there is however, scanty research related to simulation-based training for safety. Research nonetheless indicates the success of this technology in other industrial fields. For this reason, this study explored the possibility for training in safe work practices during maintenance in a gamified virtual environment. The Unreal real-time 3D game engine software was employed for creating virtual objects in the simulation. In total, 38 participants individually undertook the training in the virtual realm and provided feedback on a 5-point Likert scale. Questions pursuant to the assessment included the efficacy of acquired safety knowledge and skills, proximity of the simulation-based training to reality, and the interests and preference of SGs-IVE towards safety training. Results demonstrates participant’s perception of the prospects and learning outcome of SGs-IVE towards safety training: A factor that promotes greater cognitive learning for mindful safety practices.© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021. This is a post-peer-review, pre-copyedit version of an article published in Advances in Simulation and Digital Human Modeling: Proceedings of the AHFE 2020 Virtual Conferences on Human Factors and Simulation, and Digital Human Modeling and Applied Optimization, July 16-20, 2020, USA. The final authenticated version is available online at: http://dx.doi.org/10.1007/978-3-030-51064-0_22fi=vertaisarvioitu|en=peerReviewed

Kinetic characterization of the soluble butane monooxygenase from Thauera butanivorans, formerly ‘Pseudomonas butanovora’

Soluble butane monooxygenase (sBMO), a three-component di-iron monooxygenase complex expressed by the C2–C9 alkane-utilizing bacterium Thauera butanivorans, was kinetically characterized by measuring substrate specificities for C1–C5 alkanes and product inhibition profiles. sBMO has high sequence homology with soluble methane monooxygenase (sMMO) and shares a similar substrate range, including gaseous and liquid alkanes, aromatics, alkenes and halogenated xenobiotics. Results indicated that butane was the preferred substrate (defined by kcat : Km ratios). Relative rates of oxidation for C1–C5 alkanes differed minimally, implying that substrate specificity is heavily influenced by differences in substrate Km values. The low micromolar Km for linear C2–C5 alkanes and the millimolar Km for methane demonstrate that sBMO is two to three orders of magnitude more specific for physiologically relevant substrates of T. butanivorans. Methanol, the product of methane oxidation and also a substrate itself, was found to have similar Km and kcat values to those of methane. This inability to kinetically discriminate between the C1 alkane and C1 alcohol is observed as a steady-state concentration of methanol during the two-step oxidation of methane to formaldehyde by sBMO. Unlike methanol, alcohols with chain length C2–C5 do not compete effectively with their respective alkane substrates. Results from product inhibition experiments suggest that the geometry of the active site is optimized for linear molecules four to five carbons in length and is influenced by the regulatory protein component B (butane monooxygenase regulatory component; BMOB). The data suggest that alkane oxidation by sBMO is highly specialized for the turnover of C3–C5 alkanes and the release of their respective alcohol products. Additionally, sBMO is particularly efficient at preventing methane oxidation during growth on linear alkanes ≥C2, despite its high sequence homology with sMMO. These results represent, to the best of our knowledge, the first kinetic in vitro characterization of the closest known homologue of sMM

Discovery of new colonies by Sentinel2 reveals good and bad news for emperor

The distribution of emperor penguins is circumpolar, with 54 colony locations currently reported of which 50 are currently extant as of 2019. Here we report on eight newly discovered colonies and confirm the rediscovery of three breeding sites, only previously reported in the era before Very High Resolution satellite imagery was available, making a total of 61 breeding locations. This represents an increase of ~20% in the number of breeding sites, but, as most of the colonies appear to be small, they may only increase the total population by around 5–10%. The discoveries have been facilitated by the use of Sentinel2 satellite imagery, which has a higher resolution and more efficient search mechanism than the Landsat data previously used to search for colonies. The small size of these new colonies indicates that considerations of reproductive output in relation to metabolic rate during huddling is likely to be of interest. Some of the colonies exist in offshore habitats, something not previously reported for emperor penguins. Comparison with recent modelling results show that the geographic locations of all the newly found colonies are in areas likely to be highly vulnerable under business‐as‐usual greenhouse gas emissions scenarios, suggesting that population decreases for the species will be greater than previously thought

Novel facultative Methylocella strains are active methane consumers at terrestrial natural gas seeps

Natural gas seeps contribute to global climate change by releasing substantial amounts of the potent greenhouse gas methane and other climate-active gases including ethane and propane to the atmosphere. However, methanotrophs, bacteria capable of utilising methane as the sole source of carbon and energy, play a significant role in reducing the emissions of methane from many environments. Methylocella-like facultative methanotrophs are a unique group of bacteria that grow on other components of natural gas (i.e. ethane and propane) in addition to methane but a little is known about the distribution and activity of Methylocella in the environment. The purposes of this study were to identify bacteria involved in cycling methane emitted from natural gas seeps and, most importantly, to investigate if Methylocella-like facultative methanotrophs were active utilisers of natural gas at seep sites

Induction of Biogenic Magnetization and Redox Control by a Component of the Target of Rapamycin Complex 1 Signaling Pathway

Most organisms are simply diamagnetic, while magnetotactic bacteria and migratory animals are among organisms that exploit magnetism. Biogenic magnetization not only is of fundamental interest, but also has industrial potential. However, the key factor(s) that enable biogenic magnetization in coordination with other cellular functions and metabolism remain unknown. To address the requirements for induction and the application of synthetic bio-magnetism, we explored the creation of magnetism in a simple model organism. Cell magnetization was first observed by attraction towards a magnet when normally diamagnetic yeast Saccharomyces cerevisiae were grown with ferric citrate. The magnetization was further enhanced by genetic modification of iron homeostasis and introduction of ferritin. The acquired magnetizable properties enabled the cells to be attracted to a magnet, and be trapped by a magnetic column. Superconducting quantum interference device (SQUID) magnetometry confirmed and quantitatively characterized the acquired paramagnetism. Electron microscopy and energy-dispersive X-ray spectroscopy showed electron-dense iron-containing aggregates within the magnetized cells. Magnetization-based screening of gene knockouts identified Tco89p, a component of TORC1 (Target of rapamycin complex 1), as important for magnetization; loss of TCO89 and treatment with rapamycin reduced magnetization in a TCO89-dependent manner. The TCO89 expression level positively correlated with magnetization, enabling inducible magnetization. Several carbon metabolism genes were also shown to affect magnetization. Redox mediators indicated that TCO89 alters the intracellular redox to an oxidized state in a dose-dependent manner. Taken together, we demonstrated that synthetic induction of magnetization is possible and that the key factors are local redox control through carbon metabolism and iron supply

Cognitive bearing of techno-advances in Kashmiri carpet designing

The design process in Kashmiri carpet weaving is a distributed process encompassing a number of actors and artifacts. These include a designer called naqash who creates the design on graphs, and a coder called talim-guru who encodes that design in a specific notation called talim which is deciphered and interpreted by the weavers to weave the design. The technological interventions over the years have influenced these artifacts considerably and triggered major changes in the practice, from heralding profound cognitive accomplishments in manually driven design process causing major alterations in the overall structure of the practice. The recent intervention is by the digital technology: on the one hand, it has brought precision and speedy processing in the design process, and on the other, it has eliminated some of the crucial actors from the practice. This paper, which forms part of a larger study on the situated and distributed cognitive process in Kashmiri carpet-weaving practice, describes the technological makeover of the design artifacts involved in this practice over the years and their resultant cognitive impact on the design process as well as on the practice