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AbstractIn this study, we used a predator-enabled metagenomics strategy to sample the virome of a remote and difficult-to-access densely forested African tropical region. Specifically, we focused our study on the use of army ants of the genusDorylusthat are obligate collective foragers and group predators that attack and overwhelm a broad array of animal prey. Using 209 army ant samples collected from 29 colonies and the virion-associated nucleic acid-based metagenomics approach, we showed that a broad diversity of bacterial, plant, invertebrate and vertebrate viral sequences were accumulated by army ants: including sequences from 157 different viral genera in 56 viral families. This suggests that using predators and scavengers such as army ants to sample broad swathes of tropical forest viromes can shed light on the composition and the structure of viral populations of these complex and inaccessible ecosystems.

Abstract Craquelure is the most common defect on ancient polychrome paintings, which may deteriorate further to paint loss. Previous image processing methods, which can accurately recognize paint loss, have limited precision and efficiency in segmenting craquelure. This paper proposes a semantic segmentation method, Res-UNet, for the recognition of craquelure and paint loss in the Palace Museum, Beijing. The residual structure of ResNet-50 enables the avoidance of network degradation, and image features can be fully extracted. Using the unique skip connection module of U-Net, features of different levels are fused to improve segmentation accuracy and provide smoother craquelure edges. Three loss functions are combined to accelerate stable convergence. The model was trained on a newly built dataset based on 600 images, and tested on images both in and out of the dataset. Experimental results supported by statistical tests show that Res-UNet is a capable method of craquelure recognition, with an accuracy rate of 98.19%, and mean pixel accuracy = 93.67%. Hence, the proposed hybrid approach is a promising tool to support the preservation and restoration of valuable traditional Chinese polychrome architectural paintings.

The second plague pandemic started in Europe with the Black Death in 1346 and lasted until the 19th century. Based on ancient DNA studies, there is a scientific disagreement over whether the bacterium, Yersinia pestis, came into Europe once (Hypothesis 1) or repeatedly over the following four centuries (Hypothesis 2). Here, we synthesize the most updated phylogeny together with historical, archeological, evolutionary, and ecological information. On the basis of this holistic view, we conclude that Hypothesis 2 is the most plausible. We also suggest that Y. pestis lineages might have developed attenuated virulence during transmission, which can explain the convergent evolutionary signals, including pla decay, that appeared at the end of the pandemics. Significance Over the last few years, there has been a great deal of scientific debate regarding whether the plague bacterium, Yersinia pestis, spread from a Western European reservoir during the second plague pandemic, or if it repeatedly came to Europe from Asia. Here, we make a synthesis of the available evidence, including genomes of ancient DNA and historical, archeological, and ecological information. We conclude that the bacterium most likely came to Europe from Asia several times during the second plague pandemic.

What was the capacity of European colonial states? How fiscally extractive were they? What was their capacity to provide public goods and services? And did this change in the “developmentalist” era of colonialism? To answer these questions, we use archival sources to build a new dataset on colonial states of the second French colonial empire (1830-1962). French colonial states extracted a substantial amount of revenue, but they were under-administered because public expenditure entailed high wage costs. These costs remained a strong constraint in the “developmentalist” era of colonialism, despite a dramatic increase in fiscal capacity and large overseas subsidies. International audience

AbstractBackgroundTermites primarily feed on lignocellulose or soil in association with specific gut microbes. The functioning of the termite gut microbiota is partly understood in a handful of wood-feeding pest species but remains largely unknown in other taxa. We intend to fill this gap and provide a global understanding of the functional evolution of termite gut microbiota.ResultsWe sequenced the gut metagenomes of 145 samples representative of the termite diversity. We show that the prokaryotic fraction of the gut microbiota of all termites possesses similar genes for carbohydrate and nitrogen metabolisms, in proportions varying with termite phylogenetic position and diet. The presence of a conserved set of gut prokaryotic genes implies that essential nutritional functions were present in the ancestor of modern termites. Furthermore, the abundance of these genes largely correlated with the host phylogeny. Finally, we found that the adaptation to a diet of soil by some termite lineages was accompanied by a change in the stoichiometry of genes involved in important nutritional functions rather than by the acquisition of new genes and pathways.ConclusionsOur results reveal that the composition and function of termite gut prokaryotic communities have been remarkably conserved since termites first appeared ~ 150 million years ago. Therefore, the “world’s smallest bioreactor” has been operating as a multipartite symbiosis composed of termites, archaea, bacteria, and cellulolytic flagellates since its inception.

ABSTRACTBartonella quintana caused trench fever in the framework of two World Wars and is now recognized as an agent of re-emerging infection. Many reports indicated the popularity of B. quintana exposure since the 90s. For evaluating its prevalence in ancient populations, we used real-time PCR to detect B. quintana DNA in 400 teeth collected from 145 individuals dating from the 1st to 19th centuries in nine archeological sites with the presence of negative controls. Fisher’s exact test was used to compare the prevalence of B. quintana detection in civil and military populations. B. quintana DNA was confirmed in a total of 28/145 (19.3%) individuals, comprising 78 citizens and 67 soldiers, 20.1% and 17.9% of which were positive for B. quintana bacteremia, respectively. This study collected previous studies on these ancient samples and showed that the presence of B. quintana infection followed the course of time in human history; a total of 14/15 sites from five European countries had a positive prevalence. The positive rate in soldiers was higher than those of citizens, with 20% and 18.8%, respectively, in the 18th - 19th centuries, but the difference in frequency was not significant. These results confirmed the role of dental pulp in diagnosing B. quintana bacteremia in ancient populations and showed the incidence of B. quintana in both citizens and soldiers. Many recent findings contributed to understanding the coevolution of the relationship between B. quintana and humans.