Multiple surveys employing a new sample‐processing protocol reveal the genetic diversity of placozoans in Japan

Placozoans, flat free‐living marine invertebrates, possess an extremely simple bauplan lacking neurons and muscle cells and represent one of the earliest‐branching metazoan phyla. They are widely distributed from temperate to tropical oceans. Based on mitochondrial 16S rRNA sequences, 19 haplotypes forming seven distinct clades have been reported in placozoans to date. In Japan, placozoans have been found at nine locations, but 16S genotyping has been performed at only two of these locations. Here, we propose a new processing protocol, “ethanol‐treated substrate sampling,” for collecting placozoans from natural environments. We also report the collection of placozoans from three new locations, the islands of Shikine‐jima, Chichi‐jima, and Haha‐jima, and we present the distribution of the 16S haplotypes of placozoans in Japan. Multiple surveys conducted at multiple locations yielded five haplotypes that were not reported previously, revealing high genetic diversity in Japan, especially at Shimoda and Shikine‐jima Island. The observed geographic distribution patterns were different among haplotypes; some were widely distributed, while others were sampled only from a single location. However, samplings conducted on different dates at the same sites yielded different haplotypes, suggesting that placozoans of a given haplotype do not inhabit the same site constantly throughout the year. Continued sampling efforts conducted during all seasons at multiple locations worldwide and the development of molecular markers within the haplotypes are needed to reveal the geographic distribution pattern and dispersal history of placozoans in greater detail

A New Species of Orthonectida That Parasitizes Xenoturbella bocki: Implications for Studies on Xenoturbella

Orthonectida is a phylum of marine invertebrates known to parasitize many invertebrate animals. Because of its simple body plan, it was suggested that it belong to Mesozoa, together with Dicyemida, and that it represent the evolutionary step between unicellular organisms and multicellular animals. Recent studies, including analyses of its genomes, have clarified its phylogenetic position as a member of the Protostomia, but details such as the species diversity within the phylum and how it infects the host remain unknown. Here we report orthonectids discovered from the marine worm Xenoturbella bocki. Orthonectids were found from sections of four xenoturbellid specimens, collected eight years apart. Live females were also discovered on three separate occasions. These recurring instances of orthonectids found from Xenoturbella show that they are parasitic to the animal and not just chance contaminations. Based on morphological characters such as the presence of sexual dimorphism, the arrangement of oocytes within the female body, and the presence of crystalline inclusions in the male epidermal cells, we regard this orthonectid as a new species, Rhopalura xenoturbellae sp. nov. Since orthonectids are present within the xenoturbellid adult body, caution is needed when interpreting morphological, molecular, and experimental data from X. bocki. Further studies on R. xenoturbellae will yield important information on the fundamental biological details of orthonectids that remain unknown

Decreased levels of insulin-like growth factor-1 and vascular endothelial growth factor relevant to the ossification disturbance in femoral heads spontaneous hypertensive rats.

Ossification disturbance in femoral head reportedly is seen in the Spontaneously Hypertensive rats (SHR) between ages of 10 and 20 weeks. We investigated serum and tissue levels of insulin-like growth factor-1 (IGF-1) and vascular endothelial growth factor (VEGF) in SHR relevant to the ossification disturbance and osteonecrosis of the femoral head. Serum levels of IGF-1 and VEGF were significantly lower in SHR than in Wistar Kyoto rats (WKY) at weeks 5, 10, 15 and 20 (p<0.005). The incidence of histological ossification disturbance of the femoral head was higher in SHR (59%) than in WKY (40%) at week 20. Lower serum and local levels of VEGF in SHR appeared to be related to the incomplete ossification of the femoral heads. Immunohistochemical study showed significantly lower numbers of IGF-1 and VEGF positive chondrocytes in the femoral epiphyseal cartilage of SHR than in those of WKY at weeks 10, 15 and 20. Our results suggest that local and/or systemic levels of IGF-1 and VEGF between ages of 5 and 20 weeks might play roles in the pathogenesis of ossifi cation disturbance of the femoral head in SHR

Aire suppresses CTLA-4 expression from the thymic stroma to control autoimmunity

Impaired production of thymic regulatory T cells (Tregs) is implicated in the development of Aire-dependent autoimmunity. Because Tregs require agonistic T cell receptor stimuli by self-antigens to develop, reduced expression of self-antigens from medullary thymic epithelial cells (mTECs) has been considered to play a major role in the reduced Treg production in Aire deficiency. Here, we show that mTECs abnormally express co-inhibitory receptor CTLA-4 if Aire is non-functional. Upon binding with CD80/CD86 ligands expressed on thymic dendritic cells (DCs), the ectopically expressed CTLA-4 from Aire-deficient mTECs removes the CD80/CD86 ligands from the DCs. This attenuates the ability of DCs to provide co-stimulatory signals and to present self-antigens transferred from mTECs, both of which are required for Treg production. Accordingly, impaired production of Tregs and organ-specific autoimmunity in Aire-deficient mice are rescued by the depletion of CTLA-4 expression from mTECs. Our studies illuminate the significance of mTEC-DC interaction coordinated by Aire for the establishment of thymic tolerance

A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella

BackgroundXenoturbella is a group of marine benthic animals lacking an anus and a centralized nervous system. Molecular phylogenetic analyses group the animal together with the Acoelomorpha, forming the Xenacoelomorpha. This group has been suggested to be either a sister group to the Nephrozoa or a deuterostome, and therefore it may provide important insights into origins of bilaterian traits such as an anus, the nephron, feeding larvae and centralized nervous systems. However, only five Xenoturbella species have been reported and the evolutionary history of xenoturbellids and Xenacoelomorpha remains obscure.ResultsHere we describe a new Xenoturbella species from the western Pacific Ocean, and report a new xenoturbellid structure - the frontal pore. Non-destructive microCT was used to investigate the internal morphology of this soft-bodied animal. This revealed the presence of a frontal pore that is continuous with the ventral glandular network and which exhibits similarities with the frontal organ in acoelomorphs.ConclusionsOur results suggest that large size, oval mouth, frontal pore and ventral glandular network may be ancestral features for Xenoturbella. Further studies will clarify the evolutionary relationship of the frontal pore and ventral glandular network of xenoturbellids and the acoelomorph frontal organ. One of the habitats of the newly identified species is easily accessible from a marine station and so this species promises to be valuable for research on bilaterian and deuterostome evolution

DISPENSABLE ROLE OF AIRE IN cDCs

Aire, the defect of which is responsible for the development of autoimmunity, is predominantly expressed in medullary thymic epithelial cells, and it controls a wide variety of genes, including those of tissue-restricted Ags, for establishing thymic tolerance. Aire is also expressed from APCs in the periphery, called extrathymic Aire-expressing cells (eTACs), and their complementing role to thymic tolerance has been suggested. eTACs are composed of two distinct classes of APCs, conventional dendritic cell (cDC)–type and group 3 innate lymphoid cell (ILC3)-like–type expressing retinoic acid receptor–related orphan receptor γt (RORγt). Although the essential role of Aire in the latter in the Th17-mediated immune response against Candida albicans has been reported, the role of Aire in the cDC-type eTACs for this action has not been examined. Furthermore, the significance of Aire in the production of the transcriptome of the cDC-type eTACs remains unknown. We have approached these issues using a high-fidelity Aire-reporter mouse strain. We found that although the cDC-type eTACs dominated ILC3-like–type eTACs in number and they served as efficient APCs for the immune response against an exogenous Ag as well as for the C. albicans–specific Th17 immune response, loss of Aire in cDC-type eTACs showed no clear effect on these functions. Furthermore, loss of Aire showed no major impact on the transcriptome from cDC-type eTACs. These results suggested that Aire in cDC-type eTACs may not have a cell-intrinsic role in the immune response in contrast to the role of Aire in ILC3-like–type eTACs

The ASTRO-H X-ray Observatory

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-throughput spectrometer sensitive over 0.3-2 keV with high spectral resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray

The Quiescent Intracluster Medium in the Core of the Perseus Cluster

Clusters of galaxies are the most massive gravitationally-bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and a host of astrophysical processes. Knowledge of the dynamics of the pervasive hot gas, which dominates in mass over stars in a cluster, is a crucial missing ingredient. It can enable new insights into mechanical energy injection by the central supermassive black hole and the use of hydrostatic equilibrium for the determination of cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50 million K diffuse hot plasma filling its gravitational potential well. The Active Galactic Nucleus of the central galaxy NGC1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These likely induce motions in the intracluster medium and heat the inner gas preventing runaway radiative cooling; a process known as Active Galactic Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus cluster core, which reveal a remarkably quiescent atmosphere where the gas has a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s is found across the 60 kpc image of the cluster core. Turbulent pressure support in the gas is 4% or less of the thermodynamic pressure, with large scale shear at most doubling that estimate. We infer that total cluster masses determined from hydrostatic equilibrium in the central regions need little correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July

Hitomi (ASTRO-H) X-ray Astronomy Satellite

The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E  >  2  keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month