Comparative genomics reveals insights into avian genome evolution and adaptation

Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits

Whole-genome sequence-based analysis of thyroid function

Tiina Paunio on työryhmän UK10K Consortium jäsen.Normal thyroid function is essential for health, but its genetic architecture remains poorly understood. Here, for the heritable thyroid traits thyrotropin (TSH) and free thyroxine (FT4), we analyse whole-genome sequence data from the UK10K project (N = 2,287). Using additional whole-genome sequence and deeply imputed data sets, we report meta-analysis results for common variants (MAF >= 1%) associated with TSH and FT4 (N = 16,335). For TSH, we identify a novel variant in SYN2 (MAF = 23.5%, P = 6.15 x 10(-9)) and a new independent variant in PDE8B (MAF = 10.4%, P = 5.94 x 10(-14)). For FT4, we report a low-frequency variant near B4GALT6/ SLC25A52 (MAF = 3.2%, P = 1.27 x 10(-9)) tagging a rare TTR variant (MAF = 0.4%, P = 2.14 x 10(-11)). All common variants explain >= 20% of the variance in TSH and FT4. Analysis of rare variants (MAFPeer reviewe

First Mandible and Deciduous Dentition of Juvenile Individuals of Sinomastodon (Proboscidea, Mammalia) From the Early Pleistocene Renzidong Cave of Eastern China

Sinomastodon (Proboscidea, Mammalia) is a unique brevirostrine trilophodont gomphotheriid from Eurasia, which mainly occurs in China during the Plio-Pleistocene. Although much is known about adult individuals, the morphology of juveniles of this taxon is still poorly understood due to the scarcity of pertinent fossils. The present contribution represents the first detailed systematic study of the mandible and deciduous dentition of juvenile individuals of Sinomastodon jiangnanensis from the early Early Pleistocene (2.14-2.15Ma) Renzidong Cave of eastern China. Based on morphological comparisons, the Renzidong juvenile mandible bears, on one hand, the transitional characteristics between the typical long-jawed trilophodont and elephantoid proboscideans, and, on the other hand, more primitive features than adult mandibles of Sinomastodon. This study of juvenile individuals of S.jiangnanensis provides new information to enhance the diagnosis of S.jiangnanensis, and confirms the validity of the species. It also provides evidence to show that the morphological transition of genus Sinomastodon from Neogene to Quaternary is mirrored in adult and juvenile individuals

Ferroelectrically tunable magnetism in BiFeO3/BaTiO3 heterostructure revealed by the first-principles calculations

© 2020 The perovskite oxide interface has attracted extensive attention as a platform for achieving strong coupling between ferroelectricity and magnetism. In this work, robust control of magnetoelectric (ME) coupling in the BiFeO3/BaTiO3 (BFO/BTO) heterostructure (HS) was revealed by using the first-principles calculation. Switching of the ferroelectric polarization of BTO induce large ME effect with significant changes on the magnetic ordering and easy magnetization axis, making up for the weak ME coupling effect of single-phase multiferroic BFO. In addition, the Dzyaloshinskii-Moriya interaction (DMI) and the exchange coupling constants J for the BFO part of the HSs are simultaneously manipulated by the ferroelectric polarization, especially the DMI at the interface is significantly enhanced, which is three or four times larger than that of the individual BFO bulk. This work paves the way for designing new nanomagnetic devices based on the substantial interfacial ME effect

Magnetic domain-wall induced ferroelectric polarization in rare-earth orthoferrites AFeO3 (A = Lu, Y, Gd): first-principles calculations

The scarcity of materials with coexisting ferroelectric polarization and magnetization has hindered the development of multiferroic-based spintronic applications. Therefore, the generation of polarization in magnetic compounds is an important task in an effort to make single-phase multiferroic materials. Magnetic domain walls with strong discontinuities in spin ordering provide an ideal platform for the generation of polarization. In this work, we investigate spin-induced ferroelectric polarization at antiferromagnetic domain walls in the rare-earth orthoferrites AFeO3 (A = Lu, Y, Gd). We find that the ferroelectric polarization depends on the atomic radius of the rare-earth element, with the largest polarization of 0.092 μC cm-2 being realized in LuFeO3, which has the smallest rare-earth radius and the highest domain wall density along the b direction. Based on the octahedral distortion and the unified polarization model, we also perform a mechanistic analysis of the ferroelectric polarization at domain walls along the b direction. The different octahedral tilt angles and the different unit cell volumes caused by A-site ions are the main reasons for the polarization difference in the three compounds. Our results improve the theoretical understanding of magnetically induced ferroelectric polarization at domain walls and provide a basis for experimental application in spintronic devices based on domain wall multiferroicity

First-principles investigation on tunable electronic properties and magnetism by polarization in PbTiO3/BiFeO3 2D ferroelectric heterostructures

Perovskite oxide interfaces have been used recently as platforms for demonstrating rich physical properties that are not possessed by their bulk constituents. In this work, we will not only demonstrate rich physical properties at polar perovskite oxide interfaces, but also the tuning of such properties by switching the polarization in PbTiO3/tetragonal BiFeO3 (BFO) two-dimensional ferroelectric heterostructures (HSs). Our first-principles calculations reveal that both magnetism and conductivity can be induced by the discontinuity of the ferroelectric (FE) polarization and the valence states at the interface, and they can also be robustly manipulated by reversing polarization. These properties include the coupling between an interfacial two-dimensional electron gas and magnetism, a transition from half-metal to band insulator or Mott insulator, and the conversion from G-type antiferromagnetic order to local ferromagnetic (FM) ordering, and finally, to the local C-type antiferromagnetic order (C-AFM). Furthermore, by setting different terminations, we can artificially control the local FM ordering that occurs arbitrarily in any one of the polarization directions, and we can even control whether the local FM ordering appears at the interface or at the surface. This novel control can be applied in the fabrication of memory devices for information storage where bits can be written by an electric field (to switch ferroelectric polarization) while reading magnetically. Such a device will drastically reduce energy consumption

Tuning the magnetism of two-dimensional hematene by ferroelectric polarization

Magnetism in two-dimensional (2D) materials, that is, a 2D version of the magnetism of three-dimensional bulk materials, and the associated novel physics have recently been the focus of many spintronics researchers. Here we investigate the manipulation of 2D magnetism at the interfaces of ferromagnetic/ferroelectric hematene/BaTiO3(001) heterostructures (HSs) fabricated via a precisely chosen sequence. By introducing four types of interfaces of 2D hematene and three-dimensional BaTiO3 that induce different oxygen environments, the control of magnetism is directly demonstrated from first-principles. An obvious 2D electron gas originates from the Fe-3d and O-2p hybridization; the electron gas is sensitive to the interfacial atomic displacements. Robust control of both the direction and magnitude of the net magnetization has been realized for an Fe/TiO2 terminated bilayer HS. The electron occupancies of the dxy and dxz orbitals and changes to the Fe-O bond play a key role in determining the magnetism of our systems. Our work not only demonstrates the technique\u27s potential for manipulating magnetism in 2D hematene, but also sheds light on the underlying mechanism and the fundamental properties of hematene HSs