Publications

Species of large, testate, rhizarian protists in the genus Gromia are often common in high-latitude coastal environments, including fjords, but are frequently overlooked and almost all are undescribed. Here, we describe three new gromiid species from the Nuuk fjord system on the west coast of southern Greenland. Morphologically, the new species differ in the size and shape of the test. Gromia cucumiformis sp. nov. is elongate, up to 5.5 mm long, with a length:width (L/W) ratio of 4.3–5.5; Gromia botelliformis sp. nov. is up to 2.1 mm long, with a L/W ratio of 3.0–4.8; Gromia brevis is typically less than 1.0 mm long, with a L/W ratio around 2.0. Genetically, they are well-characterised and split between two clades. Gromia cucumiformis and G. brevis branch with several species of deep-water gromiids from the Arabian Sea and the Weddell Sea, while G. botelliformis branches with deep Weddell Sea species and several unnamed and morphologically uncharacterised gromiids from different parts of the world. Gromia botelliformis and G. brevis are currently known only from the Nuuk fjords, but sequences of G. cucumiformis from Greenland group together with sequences from Svalbard and the White Sea. Our genetic data reveal four additional clades of undescribed Gromia species. One contains sequences from Greenland, Svalbard and the White Sea, two comprises sequence from Greenland and the White Sea and one is limited to sequences from Greenland. These results demonstrate the high genetic diversity of gromiids and their widespread distribution in Arctic as well as in deep-sea environments.

We read with great interest the perspective by Bumpus (1), who describes the issue of overrepresenting individuals of European ancestry in pharmacological trials. The author highlights the inequities this can translate into and the efforts needed in reporting ethnicity in trials, in line with the STROPS guideline (2). However, this raises several concerns.

Human leukocyte antigen (HLA) genes are among the most polymorphic of our genome, as a likely consequence of balancing selection related to their central role in adaptive immunity. HLA-A and HLA-B genes were recently suggested to evolve through a model of joint divergent asymmetric selection conferring all populations, including those with severe loss of diversity, an equivalent immune potential. However, the mechanisms by which these two genes might undergo joint evolution while displaying very distinct allelic profiles in populations worldwide are still unknown. To address this issue, we carried out extensive data analyses (among which factorial correspondence and linear modelling) on 2,909 common and rare HLA-A, HLA-B and HLA-C alleles and 200,000 simulated pathogenic peptides by taking into account sequence variation, predicted peptide-binding affinity and HLA allele frequencies in 123 populations worldwide. Our results show that HLA-A and HLA-B (but not HLA-C) molecules maintain considerable functional divergence in almost all populations, which likely plays an instrumental role in their immune defence. We also provide robust evidence of functional complementarity between HLA-A and HLA-B molecules, which display asymmetric relationships in terms of amino acid diversity at both inter- and intra-protein levels and in terms of promiscuous or fastidious peptide-binding specificities. Like two wings of a flying bird, the functional complementarity of HLA-A and HLA-B is a perfect example, in our genome, of duplicated genes sharing their capacity of assuming common vital functions while being submitted to complex and sometimes distinct environmental pressures.

The Late Jurassic Allosaurus is one of the better-studied dinosaurs. A histological and geochemical study of a tibia and a femur of A. fragilis recovered in the Upper Jurassic Cleveland-Lloyd Dinosaur Quarry, Utah, United States has been done in order to address growth characteristics of this species. The two bones, probably belonging to separate individuals, are among the largest known for this species, which make them suitable to address such issues. The inclusion of our data on femur growth markings in the previously published data reflects a range of growth variability rather than two distinct growth strategies. The tibia has a well-developed external fundamental system indicating somatic maturity achievement. Using a quantitative method of superimposition to retrocalculate missing lines of arrested growth, the tibia appears to correspond to an individual that reached its skeletal maturity at 22 years and died at approximately 26 years. In the tibia, the concentration of zinc, a potential biomarker associated with bone formation, displays a higher concentration in zones of rapid growth compared to annuli. There is no direct relationship between the values of δ18Op and the lines of arrested growth distribution. The absence of relations between the histological organization and an enrichment in REE of the bone, indicates that the variations of δ18Op likely represent a diagenetic process rather than a primordial, biologic composition. However, the geochemical composition of the bones is not homogeneous along the sections, indicating that the signal variations have not been completely erased by diagenesis.

The Recent re-/discovery of unusual Lower Cretaceous continental deposits (dysodiles) brings important and exceptional paleontological assets. Dysodile beds are found in many localities across Lebanon and are characterized by their high organic matter content and their richness in exceptionally well-preserved fossils. We focus our study on five sampling localities in the lower Barremian sandstone beds, deposited when Lebanon was located in the north-eastern part of the Gondwana supercontinent. The localities are found associated with volcanic deposits suggesting a close relation between volcanism and their deposition and/or preservation. The present study provides, for the first time, insights on the fossil assemblages found in the dysodiles, including fishes, turtles, gastropods, insects, plant debris (macroflora and palynomorphs), ostracods and coprolites. We provide a preliminary reconstruction of the depositional environment that is common to the five sampling localities. It was a freshwater lake or possibly a series of interconnected lakes, in the vicinity of volcanic edifices, surrounded by a typical Lower Cretaceous flora (open forest environment), and inhabited by basal actinopterygian fishes and teleosts that will constitute the core of subsequent freshwater assemblages. The Lebanon localities have important implications for local palaeoenvironments as well as worldwide biogeography. In addition, the fossil assemblages show some taxonomic and taphonomic differences between the sampling sites, suggesting local differences in environmental conditions during deposition.

While narratives of the spread of agriculture are central to interpretation of African history, hard evidence of past crops and cultivation practices are still few. This research aims at filling this gap and better understanding the evolution of agriculture and foodways in West Africa. It reports evidence from systematic flotation samples taken at the settlement mounds of Sadia (Mali), dating from 4 phases (phase 0=before first-third century AD; phase 1=mid eighth-tenth c. AD; phase 2=tenth-eleventh c. AD; phase 3=twelfth-late thirteenth c. AD). Flotation of 2200 l of soil provided plant macro-remains from 146 archaeological samples. As on most West African sites, the most dominant plant is pearl millet (). But from the tenth century AD, sorghum () and African rice () appear in small quantities, and fonio () and barnyard millet/hungry rice ( sp.), sometimes considered weeds rather than staple crops, are found in large quantities. Some samples also show remains of tree fruits from savannah parklands, such as baobab (), marula (), jujube ( sp.), shea butter () and African grapes (). Fonio and sp. cultivation appears here to be a later addition that helped to diversify agriculture and buffer against failures that might affect the monoculture of pearl millet. This diversification at the end of the 1st millennium AD matches with other evidence found in West Africa.

In this issue of Developmental Cell, Chuyen et al. (2021) suggest that the Scf/Kit pathway controls mutual repulsion of multiciliated cells and their affinity for epidermal cell junctions through soluble and membrane-associated Scf ligands, respectively. Effective self-organizational patterning emerges at the mesoscopic scale as a small set of effective behaviors.

The Ravin Blanc I archaeological occurrence, dated to MIS 5, provides unprecedented data on the Middle Stone Age (MSA) of West Africa since well-contextualized archaeological sites pre-dating MIS 4/3 are extremely rare for this region. The combined approach on geomorphology, phytolith analysis, and OSL date estimations offers a solid framework for the MSA industry comprised in the Ravin Blanc I sedimentary sequence. The paleoenvironmental reconstruction further emphasizes on the local effects of the global increase in moisture characterizing the beginning of the Upper Pleistocene as well as the later shift to more arid conditions. The lithic industry, comprised in the lower part of the sequence and dated to MIS 5e, shows core reduction sequences among which Levallois methods are minor, as well as an original tool-kit composition, among which pieces with single wide abrupt notches, side-scrapers made by inverse retouch, and a few large crudely shaped bifacial tools. The Ravin Blanc I assemblage has neither a chronologically equivalent site to serve comparisons nor a clear techno-typological correspondent in West Africa. However, the industry represents an early MSA technology that could either retain influences from the southern West African 'Sangoan' or show reminiscences of the preceding local Acheulean. A larger-scale assessment of behavioral dynamics at work at the transition period between the Middle to Upper Pleistocene is discussed in view of integrating this new site to the global perception of this important period in the MSA evolutionary trajectories.

Actinopterygians (ray‐finned fishes) are the most diversified group of vertebrates and are characterized by a variety of protective structures covering their integument, the evolution of which has intrigued biologists for decades. Paleontological records showed that the first mineralized vertebrate skeleton was composed of dermal bony plates covering the body, including odontogenic and skeletogenic components. Later in evolution, the exoskeleton of actinopterygian's trunk was composed of scale structures. Although scales are nowadays a widespread integument cover, some contemporary lineages do not have scales but bony plates covering their trunk, whereas other lineages are devoid of any such structures. To understand the evolution of the integument coverage and particularly the transition between different structures, we investigated the pattern of scale loss events along with actinopterygian evolution and addressed the functional relationship between the scaleless phenotype and the ecology of fishes. Furthermore, we examined whether the emergence of trunk bony plates was dependent over the presence or absence of scales. To this aim, we used two recently published actinopterygian phylogenies, one including >11,600 species, and by using stochastic mapping and Bayesian methods, we inferred scale loss events and trunk bony plate acquisitions. Our results reveal that a scaled integument is the most frequent state in actinopterygians, but multiple independent scale loss events occurred along their phylogeny with essentially no scale re‐acquisition. Based on linear mixed models, we found evidence supporting that after a scale loss event, fishes tend to change their ecology and adopt a benthic lifestyle. Furthermore, we show that trunk bony plates appeared independently multiple times along the phylogeny. By using fitted likelihood models for character evolution, we show that trunk bony plate acquisitions were dependent on a previous scale loss event. Overall, our findings support the hypothesis that integument cover is a key evolutionary trait underlying actinopterygian radiation.

The order Himatismenida (Amoebozoa, Discosea) comprises naked amoebae with an organic coat that is located on the dorsal surface of the cell. The phylogenetic relationships among deeply branching genera of the Himatismenida are unclear, as data on the species diversity of the himatismenid genera is largely restricted to the derived genus . Here, we describe two new amoeba species that branch at the base of the order Himatismenida, evidenced by SSU rRNA gene and multigene analyses. Among them, a freshwater species gen. nov., sp. nov. has a dorsal cell coat consisting of flat, oval scales. This species forms a clade at the base of the Himatismenida, and the previously described , its closest relative, is transferred into the new genus as comb. nov. Although the two species are barely distinguishable by their sequence data, they are clearly distinct in morphology. Using this data, we can report the first evidence of a dorsal cell coat consisting of scales outside of the genus . The other species has a marine origin and branches deeply, close to the root of the phylogenetic tree of Himatismenida. Based on the morphology of this amoeba, it should be described as sp. nov., a new species of the genus . Analyses of the phylogenetic relationships and the ultrastructure of the deeply branching himatismenids, together with several of the newly obtained gene sequences of and suggest that some elements of the dorsal cell coat of may be ancestral for Himatismenida and have been partly retained in various more derived species of this clade, in particular, . Although actin and gene data do not resolve the higher-level relationships in Himatismenida, they correspond to the grouping of species within most genera.