A permanent, asymmetric dust cloud around the Moon.

Interplanetary dust particles hit the surfaces of airless bodies in the Solar System, generating charged and neutral gas clouds, as well as secondary ejecta dust particles. Gravitationally bound ejecta clouds that form dust exospheres were recognized by in situ dust instruments around the icy moons of Jupiter and Saturn, but have hitherto not been observed near bodies with refractory regolith surfaces. High-altitude Apollo 15 and 17 observations of a 'horizon glow' indicated a putative population of high-density small dust particles near the lunar terminators, although later orbital observations yielded upper limits on the abundance of such particles that were a factor of about 10(4) lower than that necessary to produce the Apollo results. Here we report observations of a permanent, asymmetric dust cloud around the Moon, caused by impacts of high-speed cometary dust particles on eccentric orbits, as opposed to particles of asteroidal origin following near-circular paths striking the Moon at lower speeds. The density of the lunar ejecta cloud increases during the annual meteor showers, especially the Geminids, because the lunar surface is exposed to the same stream of interplanetary dust particles. We expect all airless planetary objects to be immersed in similar tenuous clouds of dust.

Characterization of the

The isotope ^{163}Ho is in many ways the best candidate to perform experiments to investigate the value of the electron neutrino mass. It undergoes an electron capture process to ^{163}Dy with an energy available to the decay, Q_{EC}, of about 2.8 keV. According to the present knowledge, this is the lowest Q_{EC} value for such transitions. Here we discuss a newly obtained spectrum of ^{163}Ho, taken by cryogenic metallic magnetic calorimeters with ^{163}Ho implanted in the absorbers and operated in anticoincident mode for background reduction. For the first time, the atomic deexcitation of the ^{163}Dy daughter atom following the capture of electrons from the 5s shell in ^{163}Ho, the OI line, was observed with a calorimetric measurement. The peak energy is determined to be 48 eV. In addition, a precise determination of the energy available for the decay Q_{EC}=(2.858±0.010_{stat}±0.05_{syst}) keV was obtained by analyzing the intensities of the lines in the spectrum. This value is in good agreement with the measurement of the mass difference between ^{163}Ho and ^{163}Dy obtained by Penning-trap mass spectrometry, demonstrating the reliability of the calorimetric technique.

A salt-water reservoir as the source of a compositionally stratified plume on Enceladus.

The discovery of a plume of water vapour and ice particles emerging from warm fractures ('tiger stripes') in Saturn's small, icy moon Enceladus raised the question of whether the plume emerges from a subsurface liquid source or from the decomposition of ice. Previous compositional analyses of particles injected by the plume into Saturn's diffuse E ring have already indicated the presence of liquid water, but the mechanisms driving the plume emission are still debated. Here we report an analysis of the composition of freshly ejected particles close to the sources. Salt-rich ice particles are found to dominate the total mass flux of ejected solids (more than 99 per cent) but they are depleted in the population escaping into Saturn's E ring. Ice grains containing organic compounds are found to be more abundant in dense parts of the plume. Whereas previous Cassini observations were compatible with a variety of plume formation mechanisms, these data eliminate or severely constrain non-liquid models and strongly imply that a salt-water reservoir with a large evaporating surface provides nearly all of the matter in the plume.

Sodium salts in E-ring ice grains from an ocean below the surface of Enceladus.

Saturn's moon Enceladus emits plumes of water vapour and ice particles from fractures near its south pole, suggesting the possibility of a subsurface ocean. These plume particles are the dominant source of Saturn's E ring. A previous in situ analysis of these particles concluded that the minor organic or siliceous components, identified in many ice grains, could be evidence for interaction between Enceladus' rocky core and liquid water. It was not clear, however, whether the liquid is still present today or whether it has frozen. Here we report the identification of a population of E-ring grains that are rich in sodium salts ( approximately 0.5-2% by mass), which can arise only if the plumes originate from liquid water. The abundance of various salt components in these particles, as well as the inferred basic pH, exhibit a compelling similarity to the predicted composition of a subsurface Enceladus ocean in contact with its rock core. The plume vapour is expected to be free of atomic sodium. Thus, the absence of sodium from optical spectra is in good agreement with our results. In the E ring the upper limit for spectroscopy is insufficiently sensitive to detect the concentrations we found.

Multi-omics for studying and understanding polar life.

Polar ecosystems are experiencing amongst the most rapid rates of regional warming on Earth. Here, we discuss 'omics' approaches to investigate polar biodiversity, including the current state of the art, future perspectives and recommendations. We propose a community road map to generate and more fully exploit multi-omics data from polar organisms. These data are needed for the comprehensive evaluation of polar biodiversity and to reveal how life evolved and adapted to permanently cold environments with extreme seasonality. We argue that concerted action is required to mitigate the impact of warming on polar ecosystems via conservation efforts, to sustainably manage these unique habitats and their ecosystem services, and for the sustainable bioprospecting of novel genes and compounds for societal gain.

Beta spectrometry with metallic magnetic calorimeters in the framework of the European EMPIR project MetroBeta.

The aim of the European Metrology Research Project MetroBeta is to improve the knowledge of the shapes of beta spectra, both in terms of theoretical calculation and measurement. The precise knowledge of beta spectra is required for the activity standardisation of pure beta emitters. Metallic magnetic calorimeters (MMCs), a type of cryogenic detectors, with the beta emitter embedded in the absorber have proven to be among the best beta spectrometers, in particular for low-energy beta transitions. Within this project, new designs of MMCs optimized for five different beta energy ranges were developed and a new detector module was constructed. The beta spectra of 151Sm, 14C and 99Tc have been measured so far; additional measurements with 36Cl are under preparation. Improved theoretical calculation methods and complementary measurement techniques complete the project.

Close Cassini flybys of Saturn's ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus.

Saturn's main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. Data on the moons' morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. We find that the optical properties of the moons' surfaces are determined by two competing processes: contamination by a red material formed in Saturn's main ring system and accretion of bright icy particles or water vapor from volcanic plumes originating on the moon Enceladus.

Flux and composition of interstellar dust at Saturn from Cassini's Cosmic Dust Analyzer.

Interstellar dust (ISD) is the condensed phase of the interstellar medium. In situ data from the Cosmic Dust Analyzer on board the Cassini spacecraft reveal that the Saturnian system is passed by ISD grains from our immediate interstellar neighborhood, the local interstellar cloud. We determine the mass distribution of 36 interstellar grains, their elemental composition, and a lower limit for the ISD flux at Saturn. Mass spectra and grain dynamics suggest the presence of magnesium-rich grains of silicate and oxide composition, partly with iron inclusions. Major rock-forming elements (magnesium, silicon, iron, and calcium) are present in cosmic abundances, with only small grain-to-grain variations, but sulfur and carbon are depleted. The ISD grains in the solar neighborhood appear to be homogenized, likely by repeated processing in the interstellar medium.

Development of serotonin-like immunoreactivity in the embryos and larvae of nudibranch mollusks with emphasis on the structure and possible function of the apical sensory organ.

This investigation provides a light and electron microscopic examination of the development of serotonin-like immunoreactivity and structure of the apical sensory organ (ASO) in embryos and/or larvae of four nudibranch species: Berghia verrucicornis, Phestilla sibogae, Melibe leonina, and Tritonia diomedea. Serotonin-like immunoreactivity is first expressed in somata, dendrites, and axons of a group of five distinct neurons within the ASO. These neurons extend axons into an apical neuropil, a structure that is situated centrally and immediately dorsal to the cerebral commissure. Three of these neurons possess sensory dendrites that extend through the pretrochal epithelium, each supporting two cilia at their distal ends. Later development of serotonin-like immunoreactivity includes 1) axons from the apical neuropil that extend into each of the velar lobes; 2) neuron perikarya in the cerebral and pedal ganglia; 3) axons that extend through the cerebral commissure, cerebral-pedal connectives, pedal commissure, and possibly the visceral loop connective; and 4) axons extending from each pedal ganglion into the larval foot. Ultrastructurally, the ASO can be seen to be composed of three lobes and an apical neuropil that is separately delineated from the cerebral commissure. Four cell types are present within the ASO: ciliary tuft cells, type I and type II parampullary neurons, and ampullary neurons. Immunofluorescence and 3,3' diaminobenzidine tetrahydrochloride (DAB) labeling verify that the serotonergic neurons of the ASO are type I and type II parampullary neurons. The ampullary and type I parampullary neurons possess dendrites that extend through the pretrochal epithelium. These dendrites are partitioned into three bundles, one on either side of the ciliary tuft cells and a third bundle penetrating the pretrochal epithelium centrally between the ciliary tuft cells. One serotonergic type I parampullary neuron is associated with each of these bundles. Two ampullary neurons are associated with each of the lateral dendritic bundles, while the central bundle includes only one. Ultrastructural analyses of serotonergic axonal innervation arising from the ASO agree with those determined from fluorescently labeled material. The structure of the ASO and its associated serotonergic axons suggest that the serotonergic component of this structure senses environmental stimuli affecting velar function, possibly the contractility of muscle fibers in the velar lobes. Similarities and differences among the ASOs of embryos and larvae from various invertebrate phyla may provide useful data that will assist in the reconstruction of phylogenetic relationships.

Monoclonal antibodies to the molluscan small cardioactive peptide SCPB: immunolabeling of neurons in diverse invertebrates.

We reported a development of murine monoclonal antibodies to a molluscan small cardioactive peptide (SCPB) and their application to immunolabeling of neurons in several molluscan and arthropod species. In vitro stimulations of mouse lymphocytes with SCPB conjugated to a carrier protein yielded exclusively IgM class antibodies; in vivo stimulation resulted in generation of both IgM and IgG classes of antibodies. Monoclonal antibodies of the IgM class labeled identified SCP-containing neuron B11 in the frozen sections of the buccal ganglia of Tritonia diomedia. These antibodies failed to stain any neurons in whole mount preparations. A monoclonal antibody of IgG1 subclass selectively labeled neurons in both frozen sections and whole mount preparations of diverse invertebrate species. Thus, neurons B11, B12, and GE1 and several other neurons of the buccal and gastroesophageal ganglia of T. diomedia bound the antibody, and a similar pattern of immunolabeling was found in the closely related gastropod Tritonia festiva. We also observed SCPB-like immunoreactivity in the central neurons of other nudibranch and pulmonate molluscs and in examples of insect (Acheta domesticus and Tehrmobia domestica) and crustacean (Semibalanus cariosus) classes of the Arthropoda. Our results suggest a specific pattern of distribution of SCPB-like immunoreactivity in the gastropod nervous system and a broad occurrence of SCPB-like antigenicity in the diverse invertebrates.

Carcinogenic effect of cisplatin (cis-diammine-dichloroplatinum (II), CDDP) in BD IX rats.

The potent antitumor agent cis-diammine-dichloroplatinum(II) (CDDP) also has carcinogenic properties. CDDP was administered i.p. to 50 BD IX rats for 3 weeks, 3 X 1 mg/kg body weight per week. All animals were pretreated by hydration before each CDDP application, but only half the animals additionally received mannitol together with the CDDP solution, as a nephroprotective measure. To date, 455 days after the first application, 33 animals have died, 13 of them of malignancies: 12 leukemias and 1 renal fibrosarcoma. So far, no significant differences in the frequency and type of malignancies have been observed between animals which additionally received mannitol and the others which did not. In the control group of 25 animals, which received NaCl solution 0.9% i.p. (3 X 1 ml/kg per week, for 3 weeks) malignancies have not yet occurred. The high tumor incidence determined in this study reveals that the risk of secondary tumor development in patients treated with CDDP should not be disregarded.

Regenerative effects of tetrachlorodecaoxide in BD IX rats after total-body gamma irradiation.

Tetrachlorodecaoxide (TCDO) was tested for its effects in BD IX rats when combined with a single dose nearing LD50 of total-body irradiation (gamma rays, 60Co). In pilot tests we found that TCDO administrations prior to or immediately after irradiation led to a very high mortality rate (up to 90%), whereas the initiation of TCDO treatment on Day 2, 3, or 4 after irradiation lowered the death rate noticeably, with optimum results when TCDO application was started on Day 4. In our major experiment on 100 BD IX rats, it was demonstrated that the following treatment schedule considerably decreased the death rate (from 44 to 4%): 15.5 mumol TCDO/kg body wt/day on Days 4-6 after irradiation and 7.75 mumol/kg body wt/day on Days 7-11. The animals treated with TCDO showed only mild anemia in the peripheral blood, accompanied by reticulocytosis and low-grade leukocytopenia. Examination of the bone marrow on Day 12 after irradiation revealed X-ray-induced agranulocytosis in the animals that had received only physiological saline solution, whereas in the bone marrow of the animals treated with TCDO there was erythropoiesis as well as myelopoiesis. In addition, the degree of hair loss and depigmentation occurring about 1 month after irradiation was considerably reduced by TCDO. From these results it can be postulated that TCDO has two different effects: as an oxygen donator it causes radiosensitization in the tissue when given before or immediately after irradiation; as an agent stimulating phagocytes and tissue regeneration, it promotes regeneration very effectively when damage is already evident in the tissue.

Anticarcinogenic effect of tetrachlorodecaoxide after total-body gamma irradiation in rats.

Tetrachlorodecaoxygen (TCDO) therapy of acute radiation syndrome was tested for a possible influence on the development of X-ray-induced malignancies. BD IX rats were exposed to total-body irradiation (TBI, gamma rays, 9 or 11 Gy) and received daily intravenous injections of either TCDO or physiological saline solution from days 4 through 11 after TBI. The short-term TCDO therapy reduced the acute death rate markedly, but survival rates after 4 months were similar with and without TCDO. The first malignancy after TBI occurred on day 103, and over the lifetime of the animals the tumor incidence in the group given TBI (11 Gy) without TCDO treatment was 73% vs 20% in animals with short-term TCDO therapy after TBI. In particular, there was a highly significant prevention of radiation-induced leukemia [P (one-sided) < 0.001] by TCDO, and a significantly reduced incidence of malignant epithelial tumors [P (one-sided) < 0.05]. The development of sarcomas was not affected by TCDO. Long-term survival was not enhanced by TCDO due to the occurrence of bronchopneumonial infections about 1 year after TBI. In conclusion, TCDO is not only a potent therapeutic agent in acute radiation syndrome, but it also significantly reduced the carcinogenic risk in rats after exposure to ionizing radiation.

Vascular damage after photodynamic therapy of solid tumors: a view and comparison of effect in pre-clinical and clinical models at the University of Louisville.

Microvascular damage that results in blood flow stasis is a frequent consequence of photodynamic therapy. The magnitude of this response is dependent on the type of photosensitizer employed for treatment, the amount of drug and light used in therapy and the time period between drug injection and treatment. This review highlights the mechanisms that lead to blood flow stasis in tumor and normal tissues and discusses methods to increase the selectivity of vascular response.

Development of host- and symbiont-specific monoclonal antibodies and confirmation of the origin of the symbiosome membrane in a cnidarian-dinoflagellate symbiosis.

The "symbiosome membrane" as defined by Roth et al. (1988) is a single, host-derived membrane that surrounds an endosymbiotic organism, separating it from the cytoplasm of the host cell. However, in the case of cnidarian-dinoflagellate endosymbioses, clear identification of the symbiosome membrane is complicated by the fact that each algal symbiont is surrounded by multiple layers of apparent membrane. The origin and molecular nature of these membranes has been the subject of considerable debate in the literature. Here we report the development of host-specific (G12) and symbiont-specific (PC3) monoclonal antibodies that allow separation of the host and symbiont components of these multiple membranes. Using immunocytochemistry at both the light and the electron microscopic level, we present data supporting the conclusion that the definitive symbiosome membrane is a single, host-derived membrane, whereas the remainder of the underlying apparent membranes surrounding the algal cell are symbiont-derived. The potential for macromolecules associated with these membranes to act as cellular signals critical to recruiting symbionts and maintaining established symbioses is discussed.

Revised description of the fine structure of in situ "zooxanthellae" genus Symbiodinium.

The fine structure of the symbiotic dinoflagellate genus Symbiodinium has been well described. All of the published descriptions are based on tissue that was fixed in standard aldehyde and osmium fixatives and dehydrated in an ethanol series before embedding. When the technique of freeze-substitution was used to fix tissue from Cassiopeia xamachana, Aiptasia pallida, and Phyllactis flosculifera and prepare it for embedding, thecal vesicles were revealed within the in situ symbionts of all three species. Although these structures have been identified in cultured symbionts, they have never been described in the in situ symbionts. A review of the literature has revealed several instances where thecal vesicles were either overlooked or identified incorrectly. Thus the formal description of the genus Symbiodinium, which describes the in situ symbionts, contains information that is based on artifact and should be revised. A revision of the genus is suggested, and the true nature of these structures and their significance in the symbiotic association are discussed.

Comparative study on the effects of chlorite oxygen reaction product TCDO (tetrachlorodecaoxygen) and sodium chlorite solution (NaClO2) with equimolar chlorite content on bone marrow and peripheral blood of BDIX rats.

The effects of the chlorite-oxygen reaction product TCDO (tetrachlorodecaoxygen, active ingredient of the systemic application form of WF 10) were investigated on bone marrow and peripheral blood of BDIX rats in comparison to a sodium chlorite solution with a chlorite content identical to that of WF 10. Despite difficulties in determining the chemical differences between TCDO and a sodium chlorite solution, their differing effects on cells, tissue and organism were striking. The following characteristics have been observed: Stimulation of the bone marrow, evidenced by the pronounced increase in mature granulocytes, pronormo- and normoblasts, or increased cell proliferation rate, determined by means of the BrdUrd method, was achieved only with WF 10 (TCDO). Stimulation of the bone marrow led in turn to increased numbers of leucocytes and monocytes in the peripheral blood. In addition, WF 10 induced the production of large granular lymphocytes (LGLs), referred to as natural killer cells (NK-cells). In contrast, NaClO2 solution suppressed bone marrow function, exhibiting a toxic effect when given on a long-term basis. At the same time the number of mature granulocytes as well as pronormo- and normoblasts decreased, while the presence of LGLs was not observed. The results showed that TCDO is a potent stimulator of the bone marrow function and an effective modulator of the entire immune system. The toxic effect of chlorite, derived from the TCDO matrix, is not noticeable, being completely compensated by the favourable effects of TCDO.

Induction of metamorphosis in the marine gastropod Ilyanassa obsoleta: 5HT, NO and programmed cell death.

The central nervous system (CNS) of a metamorphically competent larva of the caenogastropod Ilyanassa obsoleta contains a medial, unpaired apical ganglion (AG) of approximately 25 neurons that lies above the commissure connecting the paired cerebral ganglia. The AG, also known as the cephalic or apical sensory organ (ASO), contains numerous sensory neurons and innervates the ciliated velar lobes, the larval swimming and feeding structures. Before metamorphosis, the AG contains 5 serotonergic neurons and exogenous serotonin can induce metamorphosis in competent larvae. The AG appears to be a purely larval structure as it disappears within 3 days of metamorphic induction. In competent larvae, most neurons of the AG display nitric oxide synthase (NOS)-like immunoreactivity and inhibition of NOS activity can induce larval metamorphose. Because nitric oxide (NO) can prevent cells from undergoing apoptosis, a form of programmed cell death (PCD), we hypothesize that inhibition of NOS activity triggers the loss of the AG at the beginning of the metamorphic process. Within 24 hours of metamorphic induction, cellular changes that are typical of the early stages of PCD are visible in histological sections and results of a terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in metamorphosing larvae show AG nuclei containing fragmented DNA, supporting our hypothesis.

Development of the nano-dust analyzer (NDA) for detection and compositional analysis of nanometer-size dust particles originating in the inner heliosphere.

A linear time-of-flight mass spectrometer is developed for the detection and chemical analysis of nanometer-sized particles originating near the Sun. Nano-dust particles are thought to be produced by mutual collisions between interplanetary dust particles slowly spiraling toward the Sun and are accelerated outward to high velocities by interaction with the solar wind plasma. The WAVES instruments on the two STEREO spacecraft reported the detection, strong temporal variation, and potentially high flux of these particles. Here we report on the optimization and the results from the detailed characterization of the instrument's performance using submicrometer sized dust particles accelerated to 8-60 km/s. The Nano Dust Analyzer (NDA) concept is derived from previously developed detectors. It has a 200 cm(2) effective target area and a mass resolution of approximately m/Δm = 50. The NDA instrument is designed to reliably detect and analyze nanometer-sized dust particles while being pointed close to the Sun's direction, from where they are expected to arrive. Measurements by such an instrument will determine the size-dependent flux of the nano-dust particles and its variations, it will characterize the composition of the nano-dust and, ultimately, it may determine their source. The flight version of the NDA instrument is estimated to be <5 kg and requires <10 W for operation.

An evolving view of Saturn's dynamic rings.

We review our understanding of Saturn's rings after nearly 6 years of observations by the Cassini spacecraft. Saturn's rings are composed mostly of water ice but also contain an undetermined reddish contaminant. The rings exhibit a range of structure across many spatial scales; some of this involves the interplay of the fluid nature and the self-gravity of innumerable orbiting centimeter- to meter-sized particles, and the effects of several peripheral and embedded moonlets, but much remains unexplained. A few aspects of ring structure change on time scales as short as days. It remains unclear whether the vigorous evolutionary processes to which the rings are subject imply a much younger age than that of the solar system. Processes on view at Saturn have parallels in circumstellar disks.