The Epidermis: Redox Governor of Health and Diseases

A functional epithelial barrier necessitates protection against dehydration, and ichthyoses are caused by defects in maintaining the permeability barrier in the stratum corneum (SC), the uppermost protective layer composed of dead cells and secretory materials from the living layer stratum granulosum (SG). We have found that loricrin (LOR) is an essential effector of cornification that occurs in the uppermost layer of SG (SG1). LOR promotes the maturation of corneocytes and extracellular adhesion structure through organizing disulfide cross-linkages, albeit being dispensable for the SC permeability barrier. This review takes psoriasis and AD as the prototype of impaired cornification. Despite exhibiting immunological traits that oppose each other, both conditions share the epidermal differentiation complex as a susceptible locus. We also review recent mechanistic insights on skin diseases, focusing on the Kelch-like erythroid cell-derived protein with the cap “n” collar homology-associated protein 1/NFE2-related factor 2 signaling pathway, as they coordinate the epidermis-intrinsic xenobiotic metabolism. Finally, we refine the theoretical framework of thiol-mediated crosstalk between keratinocytes and leukocytes in the epidermis that was put forward earlier.

Dike Propagation During Global Contraction: Making Sense of Conflicting Stress Histories on Mercury

Thrust fault-related landforms, smooth plains units, and impact craters and basins have all been observed on the surface of Mercury. While tectonic landforms point to a long-lived history of global cooling and contraction, smooth plains units have been inferred to represent more punctuated periods of effusive volcanism. The timings of these processes are inferred through impact cratering records to have overlapped, yet the stress regimes implied by the processes are contradictory. Effusive volcanism on Mercury is believed to have produced flood basalts through dikes, the propagation of which is dependent on being able to open and fill vertical tensile cracks when horizontal stresses are small. On the contrary, thrust faults propagate when at least one horizontal stress is very large relative to the vertical compressive stress. We made sense of conflicting stress regimes through modeling with frictional faulting theory and Earth analogue work. Frictional faulting theory equations predict that the minimum and maximum principal stresses have a predictable relationship when thrust faulting is observed. The Griffith Criterion and Kirsch equations similarly predict a relationship between these stresses when tensile fractures are observed. Together, both sets of equations limit the range of stresses possible when dikes and thrusts are observed and permitted us to calculate deviatoric stresses for regions of Earth and Mercury. Deviatoric stress was applied to test a physical model for dike propagation distance in the horizontally compressive stress regime of the Columbia River Flood Basalt Province, an Earth analogue for Borealis Planitia, the northern smooth plains, of Mercury. By confirming that dike propagation distances from sources observed in the province can be generated with the physical model, we confidently apply the model to confirm that dikes on Mercury can propagate in a horizontally compressive stress regime and calculate the depth to the source for the plains materials. Results imply that dikes could travel from ∼89 km depth to bring material from deep within the lithosphere to the surface, and that Mercury’s lithosphere is mechanically layered, with only the uppermost layer being weak.

Spectrally blue hydrated parent body of asteroid (162173) Ryugu

Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record the thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between the uppermost layer observable by remote-sensing and the pristine material from the parent body. Hayabusa2 remote-sensing observations find that on the asteroid (162173) Ryugu both north and south pole regions preserve the material least processed by space weathering, which is spectrally blue carbonaceous chondritic material with a 0–3% deep 0.7-µm band absorption, indicative of Fe-bearing phyllosilicates. Here we report that spectrally blue Ryugu’s parent body experienced intensive aqueous alteration and subsequent thermal metamorphism at 570–670 K (300–400 °C), suggesting that Ryugu’s parent body was heated by radioactive decay of short-lived radionuclides possibly because of its early formation 2–2.5 Ma. The samples being brought to Earth by Hayabusa2 will give us our first insights into this epoch in solar system history.

Identification of a divergent basal body assembly protein involved in land plant spermatogenesis

Oogamy is a form of sexual reproduction and evolved independently in animals, fungi, and plants. In streptophyte plants, Charophyceae, Coleochaetophyceae, bryophytes, lycophytes, ferns (monilophytes), and some gymnosperms (Cycads and Ginkgo) utilize spermatozoids as the male gamete. Plant spermatozoids commonly possess characteristic structures such as the spline, which consists of a microtubule array, the multilayered structure (MLS) in which the uppermost layer is continuum of the spline, and multiple flagella. However, the molecular mechanisms underpinning plant spermatogenesis remain to be elucidated. To identify the genes involved in plant spermatogenesis, we performed computational analyses and successfully found deeply divergent BLD10s by combining multiple methods and omics-data. We then validated the functions of candidate genes in the liverwort Marchantia polymorpha and the moss Physcomitrium patens and found that MpBLD10 and PpBLD10 are required for normal basal body and flagella formation. Mpbld10 mutants exhibited defects in remodeling of the cytoplasm and nucleus during spermatozoid formation, thus MpBLD10 should be involved in chromatin reorganization and elimination of the cytoplasm during spermiogenesis. Streptophyte BLD10s are orthologous to BLD10/CEP135 family proteins, which function in basal body assembly, but we found that BLD10s evolved especially fast in land plants and MpBLD10 might obtain additional functions in spermatozoid formation through the fast molecular evolution. This study provides a successful example of combinatorial study from evolutionary and molecular genetic perspectives that elucidated a function of the key protein of the basal body formation that fast evolved in land plants.

Updated statistics for crater clusters on Mars

<p>An increasing number of newly formed impact craters on Mars have been detected in the last 15 years. These small craters are normally identified via dark spots in lower resolution images that formed during the impact process, presumably through the removal or disturbance of bright surface material [1]. Later higher resolution images revealed single craters or crater clusters, which form when impactors fragment in the atmosphere, within those halos [1,2]. Due to this detection method, most of the new impact sites found are in dusty regions, which imposes an observational bias [3]. Newly formed clusters consist of two to thousands of individual craters and can be tightly clustered or spread out over hundreds of meters [2]. Since the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on Mars in 2018 [4], the search for newly formed impact craters has become even more important, because identifying impacts in seismic signals could provide further constraints on both the atmospheric and solid-body effects of impact cratering process on Mars, as well as help place further constraints on the properties of the uppermost layer of the crust. As one of InSight’s mission goals is to estimate the current impact rate on Mars, the seismic detection of impacts is also crucial [4].</p> <p>The aim of this new study is to describe the properties of the complete catalog of known newly formed craters on Mars and examine correlations between different crater cluster properties. We investigated 559 crater clusters and 493 single craters detected between 2008 and 2020 using 25 cm/px HiRISE images. The locations and diameters were noted for each single crater, as well as for every individual crater within a cluster down to 1 m diameter. This was done using ArcMap (ArcGIS) software with the three-point method of the CraterTools add-in [5]. We describe the cluster characteristics, such as the number of craters within a cluster, largest crater in a cluster, cluster effective diameter, cluster dispersion, elevation of the impact sites, and the variation in sizes of craters within a cluster.</p> <p>More than half of the new impact sites form as clusters. We did not find any differences between the spatial distribution of single and crater clusters across Mars. The mapped crater clusters from this study consist of 2 to 2334 individual craters. More than half of all clusters (58%) consist of 10 craters or less. Crater clusters containing more than 100 craters are rare. With regard to the sizes of craters within crater clusters, we found that for highly populated clusters, the majority of craters are very small, and clusters with few craters have a tendency for craters that are more equal in size. Clusters having large effective diameters contain more equally sized craters. Our results show the full range of parameter spaces that are possible for cluster properties, which can help validate theoretical atmospheric fragmentation models.</p> <p><strong>References:</strong></p> <p>[1] Malin M. C. et al. (2006) Science, 314, 1573-1577.</p> <p>[2] Daubar I. J. et al. (2019) JGR, 124, 958-969.</p> <p>[3] Daubar I. J. et al. (2013) Icarus, 225, 506-516.</p> <p>[4] Banerdt B. W. et al. (2020) Nature, 13, 183-189.</p> <p>[5] Kneissl T. et al. (2011) Planet. Space Sci., 59, 1243-1254.</p>

The role of regolith thickness in seismic shaking on asteroids

<p>Near-Earth Asteroids visited by spacecraft display a depletion in the number of small craters (< 100 m). For example, the fractured monolith 433 Eros (Thomas et al., 2005), and the rubble piles 25143 Itokawa (Michel et al., 2009), 162173 Ryugu (Noguchi et al., 2021), and 101955 Bennu (Daly et al., 2020) all show a depletion in small craters. Models of the crater populations on Eros and Itokawa indicate that the depletion can be explained by seismic shaking induced by meteorite impacts (e.g., Thomas et al., 2005; Richardson et al., 2004; 2005; Michel et al., 2009). The effects of seismic activity occur in the active layer, the uppermost layer of the regolith. Previous models of seismic shaking that recreate crater populations have used a broad range of active layer depths, ranging from 0.1 m to 5 m across various models for Itokawa and Eros (Richardson et al., 2004; 2005; 2020; Michel et al 2009; Susorney et al., 2021). However, the actual regolith thickness is poorly constrained or unknown in many cases.</p> <p>In this study, the uncertainty introduced into seismic shaking models from the assumed active layer thickness is investigated by comparing the relative timescales of crater relaxation (crater erasure). We use the Richardson et al., (2004) seismic shaking model, as modified by Michel et al., (2009) for Itokawa with impactor populations from O’Brien and Greenberg (2005). Our results show that decreasing the active layer depth leads to a nonlinear increase in the time to erase a crater. The total increase in time to erasure for a crater 20 m in diameter when changing from regolith depths of 5 m to 0.1 m is over three magnitudes, mostly accommodated between depths of 1 m to 0.1 m. We also investigated the relative timescales of crater erasure for craters of different sizes. Increasing the crater diameter leads to a non-linear increase in crater erasure time, with a 10<sup>3</sup> increase in erasure time when the diameter is increased from 5 m to 100 m.</p> <p>The high sensitivity of crater erasure time on active layer depth and crater size implies that care should be taken when inferring surface properties, in particular asteroid surface age, time since a resetting event, or depth/diameter comparisons between asteroids with different crater populations.</p> <p> </p> <p>References</p> <p>                  Daly, R.T., Bierhaus, E.B., Barnouin, O.S., Daly, M.G., Seabrook, J.A., Roberts, J.H., Ernst, C.M., Perry, M.E., Nair, H., Espiritu, R.C., Palmer, E.E., Gaskell, R.W., Weirich, J.R., Susorney, H.C.M., Johnson, C.L., Walsh, K.J., Nolan, M.C., Jawin, E.R., Michel, P., Trang, D., Lauretta, D.S., 2020. The Morphometry of Impact Craters on Bennu. Geophys. Res. Lett. 47, e89672. doi:10.1029/2020GL089672</p> <p>Michel, P., O'Brien, D.P., Abe, S., Hirata, N., 2009. Itokawa's cratering record as observed by Hayabusa: Implications for its age and collisional history. Icarus 200, 503–513. doi:10.1016/j.icarus.2008.04.002</p> <p>Noguchi, R., Hirata, N., Hirata, N., Shimaki, Y., Nishikawa, N., Tanaka, S., Sugiyama, T., Morota, T., Sugita, S., Cho, Y., Honda, R., Kameda, S., Tatsumi, E., Yoshioka, K., Sawada, H., Yokota, Y., Sakatani, N., Hayakawa, M., Matsuoka, M., Yamada, M., Kouyama, T., Suzuki, H., Honda, C., Ogawa, K., Kanamaru, M., Watanabe, S.-I., 2021. Crater depth-to-diameter ratios on asteroid 162173 Ryugu. Icarus 354, 114016. doi:10.1016/j.icarus.2020.114016</p> <p>O'Brien, D.P., Greenberg, R., 2005. The collisional and dynamical evolution of the main-belt and NEA size distribution, Icarus 178, 179</p> <p>Richardson, J.E., Melosh, H.J., Greenberg, R., 2004. Impact-induced seismic activity on asteroid 433 Eros: a surface modification process. Science 306, 1526–1529. doi:10.1126/science.1104731</p> <p>Richardson, J.E., Melosh, H.J., Greenberg, R.J., O'Brien, D.P., 2005. The global effects of impact-induced seismic activity on fractured asteroid surface morphology. Icarus 179, 325–349. doi:10.1016/j.icarus.2005.07.005</p> <p>Richardson, J.E., Steckloff, J.K., Minton, D.A., 2020. Impact-produced seismic shaking and regolith growth on asteroids 433 Eros, 2867 Šteins, and 25143 Itokawa. Icarus 347, 113811. doi:10.1016/j.icarus.2020.113811</p>

Characterization of a member of the CEACAM protein family as a novel marker of proton pump-rich ionocytes on the zebrafish epidermis

In humans, several members of the CEACAM receptor family have been shown to interact with intestinal pathogens in an inflammatory context. While CEACAMs have long been thought to be only present in mammals, recent studies have identified ceacam genes in other vertebrates, including teleosts. The function of these related genes remains however largely unknown. To gain insight into the function of CEACAM proteins in fish, we undertook the study of a putative member of the family, CEACAMz1, identified in Danio rerio. Sequence analysis of the ceacamz1 gene product predicted a GPI-anchored extracellular protein containing eleven immunoglobulin domains but revealed no evident orthology with human CEACAMs. Using a combination of RT-PCR analyses and in situ hybridization experiments, as well as a fluorescent reporter line, we showed that CEACAMz1 is first expressed in discrete cells on the ventral skin of zebrafish larvae and later on in the developing gills. This distribution remains constant until juvenile stage is reached, at which point CEACAMz1 is almost exclusively expressed in gills. We further observed that at late larval stages, CEACAMz1-expressing cells mostly localize on the afferent side of the branchial filaments and possibly in the inter-lamellar space. Using immunolabelling and 3D-reconstructions, we showed that CEACAMz1 is expressed in cells from the uppermost layer of skin epidermis. These cells are embedded within the keratinocytes pavement and we unambiguously identified them as proton-pump rich ionocytes (HR cells). As the expression of ceacamz1 is turned on concomitantly to that of other known markers of HR cells, we propose that ceacamz1 may serve as a novel marker of mature HR cells from the zebrafish epidermis.

Transcriptomics unravels molecular players shaping dorsal lip hypertrophy in the vacuum cleaner cichlid, Gnathochromis permaxillaris

Background Teleosts display a spectacular diversity of craniofacial adaptations that often mediates ecological specializations. A considerable amount of research has revealed molecular players underlying skeletal craniofacial morphologies, but less is known about soft craniofacial phenotypes. Here we focus on an example of lip hypertrophy in the benthivorous Lake Tangnayika cichlid, Gnathochromis permaxillaris, considered to be a morphological adaptation to extract invertebrates out of the uppermost layer of mud bottom. We investigate the molecular and regulatory basis of lip hypertrophy in G. permaxillaris using a comparative transcriptomic approach. Results We identified a gene regulatory network involved in tissue overgrowth and cellular hypertrophy, potentially associated with the formation of a locally restricted hypertrophic lip in a teleost fish species. Of particular interest were the increased expression level of apoda and fhl2, as well as reduced expression of cyp1a, gimap8, lama5 and rasal3, in the hypertrophic lip region which have been implicated in lip formation in other vertebrates. Among the predicted upstream transcription factors, we found reduced expression of foxp1 in the hypertrophic lip region, which is known to act as repressor of cell growth and proliferation, and its function has been associated with hypertrophy of upper lip in human. Conclusion Our results provide a genetic foundation for future studies of molecular players shaping soft and exaggerated, but locally restricted, craniofacial morphological changes in fish and perhaps across vertebrates. In the future, we advocate integrating gene regulatory networks of various craniofacial phenotypes to understand how they collectively govern trophic and behavioural adaptations.

A multi-analytical study of historical coated plaster surfaces: the examination of a nineteenth-century V&A cast of a tombstone

A multi-analytical study was designed to characterise historical coated plaster surfaces. The method was applied to investigate the surface coatings of the nineteenth-century plaster cast of the tombstone of the Presbyter Bruno that belongs to the Victoria and Albert Museum collection. At first, selected samples of the object were examined with Visible Light Reflectance and Ultra-Violet Fluorescence Optical Microscopy (VLR- and UVf-OM respectively) and Scanning Electron Microscopy (SEM) demonstrating a consistent stratigraphy featuring a bulk, an interface and an uppermost layer. The latter layer appeared to consist of an aged coating and dirt. Overpainted and repaired areas of the object generated samples that had additional layers on top of the aforementioned stratigraphy. A layer that seemed to be an additional surface varnish or a coating that had not been absorbed to the bulk has been observed in a couple of samples. Elemental characterization was carried out with energy dispersive X-ray spectroscopy (EDS) and further analyses were performed with X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectroscopy with focal plane array (FPA) imaging which confirmed that the bulk of the object is made of gypsum plaster containing mostly silicate and carbonate inclusions. Gas chromatography/mass spectrometry (GC/MS) and pyrolysis-GC/MS with extraction methods based on n-propanol followed by pentafluoropropionic anhydride (PFPA), tetramethylammonium hydroxide (TMAH) and 3-trifluoromethylphenyltrimethylammonium hydroxide (m-TFPTAH) were performed to detect organic media. The results suggest that the organic medium used for the surface coating is a diterpenic resin that contained silicon, aluminium and traces of other inorganic elements. The organic medium of overpainted areas was based on alkyd resins and the in-paints were characterised as a blend of silicon and barium at varied concentrations. This multi-analytical approach can generate a better understanding of manufacturing, component materials and conservation issues of coated plaster objects.

Microbial-driven Impact of the Topmost Bed Sediment Layer on Aquatic Phosphate Fluxes

<p>There is a longstanding principle that the uppermost layer of aquatic sediment is the primary regulator of nutrient loads in the bottom water zone, pertaining to the fact that it is significantly biological in nature and thus the site of a myriad of biota-associated processes. Nevertheless, although this principle is seemingly obvious, there is unusually scant literature corroborating the impact of the uppermost sediment layer on water column nutrient fluxes, in particular soluble reactive phosphorus (SRP). It has also been theorized that in certain environments, large bacteria play a major role in phosphorus cycling in the sediment. This challenges the prevailing dogma that the control of bottom water phosphate (PO<sub>4</sub><sup>3-</sup>) is mainly attributed to the SRP flux contribution from iron (Fe) oxide-bound P in sediment or remineralisation under anoxia and warming conditions respectively. In this study, elevated temperature as well as anoxic incubation treatments were set up to demonstrate that in response to an increased level of PO<sub>4</sub><sup>3-</sup> being released under stressful conditions, the topmost bed sediment layer (TBSL) has an unmistakable impact on P sequestration and stabilisation of the bottom water PO<sub>4</sub><sup>3-</sup> fluxes. Likewise, we also show that large filamentous microorganisms residing in the TBSL were seemingly active in polyphosphate (polyP) accumulation during these stress-inducing conditions. This therefore strongly points to a new and important biological sink for the SRP flux at the benthic layer of an aquatic environment.</p>