Antiferromagnetic spintronics

Antiferromagnetic materials are magnetic inside, however, the direction of their ordered microscopic moments alternates between individual atomic sites. The resulting zero net magnetic moment makes magnetism in antiferromagnets invisible on the outside. It also implies that if information was stored in antiferromagnetic moments it would be insensitive to disturbing external magnetic fields, and the antiferromagnetic element would not affect magnetically its neighbors no matter how densely the elements were arranged in a device. The intrinsic high frequencies of antiferromagnetic dynamics represent another property that makes antiferromagnets distinct from ferromagnets. The outstanding question is how to efficiently manipulate and detect the magnetic state of an antiferromagnet. In this article we give an overview of recent works addressing this question. We also review studies looking at merits of antiferromagnetic spintronics from a more general perspective of spin-ransport, magnetization dynamics, and materials research, and give a brief outlook of future research and applications of antiferromagnetic spintronics.Comment: 13 pages, 7 figure

Expression and In Vivo Rescue of Human ABCC6 Disease-Causing Mutants in Mouse Liver

Loss-of-function mutations in ABCC6 can cause chronic or acute forms of dystrophic mineralization described in disease models such as pseudoxanthoma elasticum (OMIM 26480) in human and dystrophic cardiac calcification in mice. The ABCC6 protein is a large membrane-embedded organic anion transporter primarily found in the plasma membrane of hepatocytes. We have established a complex experimental strategy to determine the structural and functional consequences of disease-causing mutations in the human ABCC6. The major aim of our study was to identify mutants with preserved transport activity but failure in intracellular targeting. Five missense mutations were investigated: R1138Q, V1298F, R1314W, G1321S and R1339C. Using in vitro assays, we have identified two variants; R1138Q and R1314W that retained significant transport activity. All mutants were transiently expressed in vivo, in mouse liver via hydrodynamic tail vein injections. The inactive V1298F was the only mutant that showed normal cellular localization in liver hepatocytes while the other mutants showed mostly intracellular accumulation indicating abnormal trafficking. As both R1138Q and R1314W displayed endoplasmic reticulum localization, we tested whether 4-phenylbutyrate (4-PBA), a drug approved for clinical use, could restore their intracellular trafficking to the plasma membrane in MDCKII and mouse liver. The cellular localization of R1314W was significantly improved by 4-PBA treatment, thus potentially rescuing its physiological function. Our work demonstrates the feasibility of the in vivo rescue of cellular maturation of some ABCC6 mutants in physiological conditions very similar to the biology of the fully differentiated human liver and could have future human therapeutic application

Biodiversity of “Non-model” Rickettsiales and Their Association with Aquatic Organisms

Representatives of the order Rickettsiales are obligate intracellular bacteria, traditionally including well-studied pathogens of humans and other vertebrates, such as Rickettsia, Orientia, Anaplasma, and Ehrlichia. In the last two decades, studies based on molecular characterization techniques have reshaped our view on the biodiversity of Rickettsiales, and the eukaryotic hosts they can exploit. Several new genera have been described in “traditional” Rickettsiales families Rickettsiaceae and Anaplasmataceae. Moreover, a new family, “Candidatus Midichloriaceae,” displaying diversity at least comparable with the “traditional” ones, has been described. Recent data show that the majority of extant genera of Rickettsiales (16 out of 24) are hosted exclusively (or at least partly) by aquatic organisms, such as protists (e.g., ciliates, amoebas, flagellates), and animals (e.g., cnidarians, mollusks, tunicates, leeches), while only ten genera include some terrestrial host, such as arthropods. Given the highly interwoven phylogenetic relationships among Rickettsiales hosted by aquatic and terrestrial hosts, it is likely that the ancestral host of Rickettsiales was an aquatic protist organism, and the adaptation to terrestrial environments occurred independently in several distinct sublineages at least six times. Newly discovered lineages of “non-model” Rickettsiales present unforeseen features for the order such as the presence of flagella. Future investigations on “non-model” Rickettsiales are crucial to gain insight on the evolutionary history of the whole group, including the origin of molecular mechanisms involved in pathogenesis for humans and vertebrates