The Halogenated Metabolism of Brown Algae (Phaeophyta), Its Biological Importance and Its Environmental Significance

Brown algae represent a major component of littoral and sublittoral zones in temperate and subtropical ecosystems. An essential adaptive feature of this independent eukaryotic lineage is the ability to couple oxidative reactions resulting from exposure to sunlight and air with the halogenations of various substrates, thereby addressing various biotic and abiotic stresses i.e., defense against predators, tissue repair, holdfast adhesion, and protection against reactive species generated by oxidative processes. Whereas marine organisms mainly make use of bromine to increase the biological activity of secondary metabolites, some orders of brown algae such as Laminariales have also developed a striking capability to accumulate and to use iodine in physiological adaptations to stress. We review selected aspects of the halogenated metabolism of macrophytic brown algae in the light of the most recent results, which point toward novel functions for iodide accumulation in kelps and the importance of bromination in cell wall modifications and adhesion properties of brown algal propagules. The importance of halogen speciation processes ranges from microbiology to biogeochemistry, through enzymology, cellular biology and ecotoxicology

The Influence of pCO2 and Temperature on Gene Expression of Carbon and Nitrogen Pathways in Trichodesmium IMS101

Growth, protein amount, and activity levels of metabolic pathways in Trichodesmium are influenced by environmental changes such as elevated pCO2 and temperature. This study examines changes in the expression of essential metabolic genes in Trichodesmium grown under a matrix of pCO2 (400 and 900 µatm) and temperature (25 and 31°C). Using RT-qPCR, we studied 21 genes related to four metabolic functional groups: CO2 concentrating mechanism (bicA1, bicA2, ccmM, ccmK2, ccmK3, ndhF4, ndhD4, ndhL, chpX), energy metabolism (atpB, sod, prx, glcD), nitrogen metabolism (glnA, hetR, nifH), and inorganic carbon fixation and photosynthesis (rbcL, rca, psaB, psaC, psbA). nifH and most photosynthetic genes exhibited relatively high abundance and their expression was influenced by both environmental parameters. A two to three orders of magnitude increase was observed for glnA and hetR only when both pCO2 and temperature were elevated. CO2 concentrating mechanism genes were not affected by pCO2 and temperature and their expression levels were markedly lower than that of the nitrogen metabolism and photosynthetic genes. Many of the CO2 concentrating mechanism genes were co-expressed throughout the day. Our results demonstrate that in Trichodesmium, CO2 concentrating mechanism genes are constitutively expressed. Co-expression of genes from different functional groups were frequently observed during the first half of the photoperiod when oxygenic photosynthesis and N2 fixation take place, pointing at the tight and complex regulation of gene expression in Trichodesmium. Here we provide new data linking environmental changes of pCO2 and temperature to gene expression in Trichodesmium. Although gene expression indicates an active metabolic pathway, there is often an uncoupling between transcription and enzyme activity, such that transcript level cannot usually be directly extrapolated to metabolic activity

Evolution of alternative biosynthetic pathways for vitamin C following plastid acquisition in photosynthetic eukaryotes.

Ascorbic acid (vitamin C) is an enzyme co-factor in eukaryotes that also plays a critical role in protecting photosynthetic eukaryotes against damaging reactive oxygen species derived from the chloroplast. Many animal lineages, including primates, have become ascorbate auxotrophs due to the loss of the terminal enzyme in their biosynthetic pathway, L-gulonolactone oxidase (GULO). The alternative pathways found in land plants and Euglena use a different terminal enzyme, L-galactonolactone dehydrogenase (GLDH). The evolutionary processes leading to these differing pathways and their contribution to the cellular roles of ascorbate remain unclear. Here we present molecular and biochemical evidence demonstrating that GULO was functionally replaced with GLDH in photosynthetic eukaryote lineages following plastid acquisition. GULO has therefore been lost repeatedly throughout eukaryote evolution. The formation of the alternative biosynthetic pathways in photosynthetic eukaryotes uncoupled ascorbate synthesis from hydrogen peroxide production and likely contributed to the rise of ascorbate as a major photoprotective antioxidant

Length-scale-dependent ion dynamics in Ca-doped Na₃PS₄

The sodium ion conductor Na3PS4 is a promising electrolyte for future all-solid-state batteries using Na+ ions as ionic charge carriers. Its readily available components make it a compelling and more sustainable alternative to recent Li-ion technologies. At ambient temperature, the ionic conductivity is in the order of 10–4 S cm–1, which can be optimized by adjusting doping and processing parameters. Even though several studies have focused on explaining the dynamic properties of doped and undoped Na3PS4, the driving forces that lead to fast Na+ exchange are not yet completely understood. Here, we synthesized nanocrystalline, defect-rich cubic Na3PS4 via a solid-state synthesis route and compared its properties with those of highly crystalline Ca-doped Na3–2xCaxPS4. The interconnected effects of doping and synthesis procedure on both structure and dynamic properties are investigated. X-ray diffraction reveals that the undoped samples show clear cubic and tetragonal symmetry, while for the doped samples, a phase mixture of both polymorphs is seen. High-resolution 23Na magic angle spinning NMR spectra acquired at temperatures as low as −60 °C clearly reveal two different Na sites when ionic motion is partially frozen out. Ion dynamics of the powder samples were analyzed using high-precision broadband impedance spectroscopy and variable-temperature, time-domain 23Na NMR spin–lattice relaxation rate measurements. Localized Na+ jumps detected by NMR showed higher energy barriers but faster Na+ dynamics for the Ca-doped samples. A similar trend was observed in conductivity spectroscopy with lowest activation energy for Na-ion transport in tetragonal Na3PS4 but highest attempt frequencies for the hopping motion in Ca-doped Na3PS4 with x = 0.135, making the doped sample the superior ion conductor at elevated temperatures. Our study highlights the importance of breaking down ionic transport in its elemental steps to understand the complex interplay of intrinsic and extrinsic parameters in solid electrolyte materials

Inkjet‐Printed and Nanopatterned Photonic Phosphor Motifs with Strongly Polarized and Directional Light‐Emission [Dataset]

Herein a versatile and scalable method to prepare periodically corrugated nanophosphor surface patterns displaying strongly polarized and directional visible light emission is demonstrated. A combination of inkjet printing and soft lithography techniques is employed to obtain arbitrarily shaped light emitting motifs. Such predesigned luminescent drawings, in which the polarization and angular properties of the emitted light are determined and finely tuned through the surface relief, can be used as anti-counterfeiting labels, as these two specific optical features provide additional means to identify any unauthorized or forged copy of the protected item. The potential of this approach is exemplified by processing a self-standing photoluminescent quick response (QR) code whose emission is both polarized and directionally beamed. Physical insight of the mechanism behind the directional out-coupled photoluminescence observed is provided by finitedifference time-domain calculations.This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (NANOPHOM, grant agreement no. 715832) and from the Spanish Ministry of Science and Innovation under grant PID2020-116593RB-I00, funded by MCIN/AEI/10.13039/501100011033, and of the Junta de Andalucía under grant P18-RT-2291 (FEDER/UE). E. C. O. acknowledges the grant FPU19/00346 funded by MCIN/AEI/10.13039/501100011033 and ESF Investing in your Future. M. R. thanks CSIC for funding through a JAE Intro ICU scholarship (JAEICU-21-ICMS-21). This work has been partially supported by the European Union and the State of Upper Austria within the strategic program Innovative Upper Austria 2020 and #upperVision2030, project: WI2020-578813/4 “DigiManu (Extended 2021)Peer reviewe