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International audience; On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower ε50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, ∼400 °C). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.

Main text The UK has a long history of meteorite falls (where the meteorite fireball is witnessed, and the stone recovered, dating back to 1623 (MetBull, 2020). But the last meteorite fall in the UK was nearly 30 years ago when the Glatton stone, an L6 ordinary chondrite was recovered in 1991 (Hutchinson et al., 1991). Meteorite falls are important samples as they are usually recovered within days of the fireball event. As such, they have not experienced the deleterious effects terrestrial weathering that can change their extraterrestrial mineralogy, chemistry and isotopic composition (Bland et al., 2006). In exceptional circumstances rapidly recovered falls may have avoided rainfall so that soluble extraterrestrial minerals such as salts may be preserved (Chan et al., 2018). Therefore, meteorite falls represent much more pristine extraterrestrial material than their find counterparts within the same group, and consequently, characterisation of their texture and chemical signatures provides a clearer window into solar system processes. However, even falls are limited in their interpretive power as the geological context of the stone (i.e. where in the solar system it originated from) is unknown. To derive this contextual information requires the imaging of the fireball event from multiple geographical positions (Devillepoix et al., 2020). This data provides two vital pieces of information; the initial orbit of the meteoroid can be calculated and the final fall position can be predicted with increased accuracy (Devillepoix et al., 2020). As such, dedicated fireball camera networks (Bowden, 2006) are entering ‘a golden age’ with improvements in hardware and software capabilities as well as a reduction in production costs (Spurný et al., 2014). Continent-scale observatories have been established (Howie et al., 2017) and global networks are under construction (Devillepoix et al., 2020). In addition, these same developments have enabled the amateur astronomy community to construct their own networks either as groups or individuals with functional data pipelines and observations that can rival funded networks. Consequently, the number of recovered meteorite falls with orbits globally has grown rapidly over recent years (Borovička et al., 2015). The UK is a hotbed for such activity but does not have a recent recovered meteorite fall…yet. There are currently two active academically funded networks in the UK: the UK Fireball Network (UKFN: part of the Global Fireball Observatory built on the hardware and software developed by the Desert Fireball Network in Australia), and the System for Capture of Asteroid and Meteorite Paths (SCAMP; the UK arm of the French-led Fireball Recovery and InterPlanetary Observation Network (FRIPON)) (Figure 1, 2). In addition, there are two major amateur networks the UK Meteor Observation Network (UKMON), and NEMETODE, as well as an emerging presence of the Raspberry-Pi based Global Meteor Network and countless individual citizen scientists also imaging the UK night skies (Figure 1, 2). However, environmental factors in the UK such as light pollution and regular low-lying cloud cover means that a single fireball may not be captured multiple times by one network, preventing them from calculating an orbit and accurate fall position. As such, these networks, together with UK planetary scientists and National museums, have formed a collaborative data-sharing initiative called the UK Fireball Alliance (UKFAll) in order to maximise the chances of capturing a meteorite-dropping fireball event that makes landfall on the UK. Since the initiation of UKFAll in late 2018 many joint fireball observations have been made between UK networks including a fireball on the 16th February 2020 that likely dropped a few 10s of grams of extraterrestrial material into the North Sea (Figure 3). However, the diversity of hardware, software and data processing pipelines for capturing fireball events vary between camera networks. This hinders the speed of detecting and triangulating a meteorite-dropping fireball event as each fireball requires a bespoke solution to translate the data into the other networks’ format. A consistent method for rapidly transferring and converting the diversity of outputs produced by each network into a standard format that can be read and utilised by each network is required and is critical to facilitate a rapid UK response to fireball events and associated recovery effort. Here we describe the first iteration of a new code that will enable rapid conversion of data outputs from both video and still image camera networks. The code provides an effective bridging solution, while the ultimate aim is to agree and implement a globally accepted standardised format for fireball observations that can be readily transferred and utilised between camera networks to facilitate meteorite fall recovery. We also describe the logistical issues encountered by UKFAll and the solutions being implemented, including: recruitment of citizen scientists as searchers; conduct and liability issues; and best practice for collection. References Bland, P.A., et al., (2006). Weathering of chondritic meteorites. Meteorites and the early solar system II, 1, 853-867. Borovička J., et al., (2015). Small near‐Earth asteroids as a source of meteorites. In Asteroids IV, edited by Michel P., DeMeo F.E., and Bottke W.F. Tucson, Arizona: University of Arizona Press. pp. 257–280. Bowden, A.J. 2006. “Meteorite provenance and the asteroid connection”. In The history of meteoritics and key meteorite collections; fireballs, falls and finds, Edited by: G.J.H., McCall, A.J., Bowden and R.J., Howarth. Vol. 256, 379–403. Geological Society, London, Special Publications. Chan, Q.H., et al., (2018). Organic matter in extraterrestrial water-bearing salt crystals. Science advances, 4(1), eaao3521. Devillepoix, H.A., et al., (2018). The dingle dell meteorite: a halloween treat from the main belt. Meteoritics & Planetary Science, 53(10), 2212-2227. Devillepoix, H.A.R., et al., (2020). A Global Fireball Observatory. arXiv preprint arXiv:2004.01069. Howie, R.M., et al., (2017). How to build a continental scale fireball camera network. Experimental Astronomy, 43(3), 237-266. Hutchison, R., et al., (1991). The L6 chondrite fall at Glatton, England, 1991 May 5. Meteoritics, 26, 349. MetBull (2020), The meteoritical bulletin database. URL: https://www.lpi.usra.edu/meteor/metbull.php Spurný P., et al., (2014). Reanalysis of the Benešov bolide and recovery of polymict breccia meteorites—Old mystery solved after 20 years. Astronomy & Astrophysics 570:A39.

Non-classical MHC class I molecule HLA-E is the ligand for CD94/NKG2 NK cell receptors. Surface expression of HLA-E requires binding of specific HLA class I leader sequences. The uterine mucosa in early pregnancy (decidua) is infiltrated by large numbers of NK cells, which are closely associated with placental trophoblast cells. In this study we demonstrate that trophoblast cells express HLA-E on their cell surface in addition to the previously reported expression of HLA-G and HLA-C. Furthermore, we show that the vast majority of decidual NK cells bind to HLA-E tetrameric complexes and this binding is inhibited by mAb to CD94. Thus, recognition of fetal HLA-E by decidual NK cells may play a key role in regulation of placentation. The functional consequences of decidual NK cell interaction were investigated in cytotoxicity assays using polyclonal decidual NK cells. The overall effect of CD94/NKG2 interaction with HLA-E is inhibition of cytotoxicity by decidual NK cells. However, since decidual NK cells are unable to kill trophoblast even in the presence of mAb to MHC class I molecules and NK cell receptors, HLA-E interaction with CD94/NKG2 receptors may regulate other functions besides cytolysis during implantation.

Background Chagas disease is a vector-borne parasitic disease of major public health importance. Current prevention efforts are based on triatomine vector control to reduce transmission to humans. Success of vector control interventions depends on their acceptability and value to affected communities. We aimed to identify opportunities for and barriers to improved vector control strategies in the Yucatan peninsula, Mexico. Methodology/principal findings We employed a sequence of qualitative and quantitative research methods to investigate knowledge, attitudes and practices surrounding Chagas disease, triatomines and vector control in three rural communities. Our combined data show that community members are well aware of triatomines and are knowledgeable about their habits. However, most have a limited understanding of the transmission dynamics and clinical manifestations of Chagas disease. While triatomine control is not a priority for community members, they frequently use domestic insecticide products including insecticide spray, mosquito coils and plug-in repellents. Families spend about $32 US per year on these products. Alternative methods such as yard cleaning and window screens are perceived as desirable and potentially more effective. Screens are nonetheless described as unaffordable, in spite of a cost comparable to the average annual spending on insecticide products. Conclusion/Significance Further education campaigns and possibly financing schemes may lead families to redirect their current vector control spending from insecticide products to window screens. Also, synergism with mosquito control efforts should be further explored to motivate community involvement and ensure sustainability of Chagas disease vector control., Author Summary Chagas disease is an important parasitic disease transmitted by triatomine bugs. Current prevention efforts are based on eliminating triatomines from homes to reduce disease transmission to humans. However, the success of these control interventions depends on their acceptability and value to affected communities. We aimed to identify opportunities for and barriers to triatomine control strategies in the Yucatan peninsula, Mexico. We used a sequence of group discussion, interviews, and a survey to investigate the perception and knowledge of communities on Chagas disease and triatomines in three villages from the Yucatan peninsula, Mexico. Inhabitants are rather familiar with triatomine bugs, but do not associate well these bugs with Chagas disease and its clinical manifestations. Mosquito rather than triatomine control is a common preoccupation, and households frequently use insecticide spray, mosquito coils and plug-in repellents, spending about $32 US per year on these products. Alternative methods such as yard cleaning and window screens are perceived as desirable and potentially more effective. Screens are nonetheless described as unaffordable. The promotion of education campaigns and possibly financing schemes could help families to redirect their current spending from insecticide products to window screens. Also, synergism with mosquito control efforts should be further explored to motivate community involvement and ensure sustainability of Chagas disease vector control.

The crucial immunological function of the classical human major histocompatibility complex (MHC) class I molecules, human histocompatibility leukocyte antigen (HLA)-A, -B, and -C, is the presentation of peptides to T cells. A secondary function is the inhibition of natural killer (NK) cells, mediated by binding of class I molecules to NK receptors. In contrast, the function of the nonclassical human MHC class I molecules, HLA-E, -F, and -G, is still a mystery. The specific expression of HLA-G in placental trophoblast suggests an important role for this molecule in the immunological interaction between mother and child. The fetus, semiallograft by its genotype, escapes maternal allorecognition by downregulation of HLA-A and HLA-B molecules at this interface. It has been suggested that the maternal NK recognition of this downregulation is balanced by the expression of HLA-G, thus preventing damage to the placenta. Here, we describe the partial inhibition of NK lysis of the MHC class I negative cell line LCL721.221 upon HLA-G transfection. We present three NK lines that are inhibited via the interaction of their NKAT3 receptor with HLA-G and with HLA-Bw4 molecules. Inhibition can be blocked by the anti-NKAT3 antibody 5.133. In conclusion, NK inhibition by HLA-G via NKAT3 may contribute to the survival of the fetal semiallograft in the mother during pregnancy.

In this study, the CD3- LGL/NK cells present in the pregnant human uterus have been characterized. Phenotypic and morphologic analyses of decidual LGL revealed many similarities to the minor CD56bright+, CD16-subset in peripheral blood, but there were some important differences. The relative surface density of CD56+is greatly increased on decidual LGL to 22 x that found on the majority of CD56 peripheral blood NK cells. The CD56bright cells in decidua show LGL morphology, whereas in peripheral blood, they are .mainly agranular. Proliferation of CD56+cells occurs predominantly during the nonpregnant secretory (luteal) phase, indicating these CD56+uterine LGL do not migrate as terminally differentiated cells. The appearance of CD56 cells was examined at the ultrastructural level using immunoelectron microscopy. Cells with phenotypic characteristics of decidual LGL occur in a higher percentage (1.11%) in the peripheral blood of women of reproductive age than in men (0.66%). On the basis of these results, it is proposed that the CD56bright+uterine leukocytes represent a distinctive, hormonally regulated subset possibly adapted to control human placentation.