Reconstruction of ancient microbial genomes from the human gut.

Loss of gut microbial diversity1-6 in industrial populations is associated with chronic diseases7, underscoring the importance of studying our ancestral gut microbiome. However, relatively little is known about the composition of pre-industrial gut microbiomes. Here we performed a large-scale de novo assembly of microbial genomes from palaeofaeces. From eight authenticated human palaeofaeces samples (1,000-2,000 years old) with well-preserved DNA from southwestern USA and Mexico, we reconstructed 498 medium- and high-quality microbial genomes. Among the 181 genomes with the strongest evidence of being ancient and of human gut origin, 39% represent previously undescribed species-level genome bins. Tip dating suggests an approximate diversification timeline for the key human symbiont Methanobrevibacter smithii. In comparison to 789 present-day human gut microbiome samples from eight countries, the palaeofaeces samples are more similar to non-industrialized than industrialized human gut microbiomes. Functional profiling of the palaeofaeces samples reveals a markedly lower abundance of antibiotic-resistance and mucin-degrading genes, as well as enrichment of mobile genetic elements relative to industrial gut microbiomes. This study facilitates the discovery and characterization of previously undescribed gut microorganisms from ancient microbiomes and the investigation of the evolutionary history of the human gut microbiota through genome reconstruction from palaeofaeces.

A nontuberculous mycobacterium could solve the mystery of the lady from the Franciscan church in Basel, Switzerland.

BACKGROUND: In 1975, the mummified body of a female has been found in the Franciscan church in Basel, Switzerland. Molecular and genealogic analyses unveiled her identity as Anna Catharina Bischoff (ACB), a member of the upper class of post-reformed Basel, who died at the age of 68 years, in 1787. The reason behind her death is still a mystery, especially that toxicological analyses revealed high levels of mercury, a common treatment against infections at that time, in different body organs. The computed tomography (CT) and histological analysis showed bone lesions in the femurs, the rib cage, and the skull, which refers to a potential syphilis case. RESULTS: Although we could not detect any molecular signs of the syphilis-causing pathogen Treponema pallidum subsp. pallidum, we realized high prevalence of a nontuberculous mycobacterium (NTM) species in brain tissue sample. The genome analysis of this NTM displayed richness of virulence genes and toxins, and similarity to other infectious NTM, known to infect immunocompromised patients. In addition, it displayed potential resistance to mercury compounds, which might indicate a selective advantage against the applied treatment. This suggests that ACB might have suffered from an atypical mycobacteriosis during her life, which could explain the mummy's bone lesion and high mercury concentrations. CONCLUSIONS: The study of this mummy exemplifies the importance of employing differential diagnostic approaches in paleopathological analysis, by combining classical anthropological, radiological, histological, and toxicological observations with molecular analysis. It represents a proof-of-concept for the discovery of not-yet-described ancient pathogens in well-preserved specimens, using de novo metagenomic assembly.

Microscopic Evidence of Malaria Infection in Visceral Tissue from Medici Family, Italy.

Microscopy of mummified visceral tissue from a Medici family member in Italy identified a potential blood vessel containing erythrocytes. Giemsa staining, atomic force microscopy, and immunohistochemistry confirmed Plasmodium falciparum inside those erythrocytes. Our results indicate an ancient Mediterranean presence of P. falciparum, which remains responsible for most malaria deaths in Africa.

The Current Situation of the Tyrolean Iceman.

The Tyrolean Iceman, commonly known as Ötzi, is the world's oldest glacier mummy and one of the best investigated ancient human remains in the world. Since the discovery of the 5,300-year-old Copper Age individual in 1991, in a glacier in the Eastern Italian Alps, a variety of morphological, biochemical, and molecular analyses have been performed that revealed important insights into his origin, his life habits, and the circumstances surrounding his demise. In more recent research, the mummy was subjected to cutting-edge modern research methodologies currently focusing on high-throughput sequence analysis of ancient biomolecules (DNA, proteins, lipids) that are still preserved in the mummified tissues. This application of innovative "-omics" technologies revealed novel insights on the ancestry, disease predisposition, diet, and the presence of pathogens in the glacier mummy. In this review, the most important and actual results of the molecular studies will be highlighted.

miRNAs in Ancient Tissue Specimens of the Tyrolean Iceman.

The analysis of nucleic acids in ancient samples is largely limited to DNA. Small noncoding RNAs (microRNAs) are known to be evolutionary conserved and stable. To gain knowledge on miRNAs measured from ancient samples, we profiled microRNAs in cryoconserved mummies. First, we established the approach on a World War One warrior, the "Kaiserjäger", which has been preserved for almost one century. Then, we profiled seven ancient tissue specimens including skeletal muscle, stomach mucosa, stomach content and two corpus organ tissues of the 5,300-year-old copper age mummy Iceman and compared these profiles to the presence of organ-specific miRNAs in modern tissues. Our analyses suggest the presence of specific miRNAs in the different Iceman's tissues. Of 1,066 analyzed human miRNAs, 31 were discovered across all biopsies and 87 miRNAs were detected only in a single sample. To check for potential microbiological contaminations, all miRNAs detected in Iceman samples and not present in ancient samples were mapped to 14,582 bacterial and viral genomes. We detected few hits (3.9% of miRNAs compared with 3.6% of miRNAs). Interestingly, the miRNAs with higher abundance across all ancient tissues were significantly enriched for Guanine (P value of 10-13) and Cytosine (P value of 10-7). The same pattern was observed for modern tissues. Comparing miRNAs measured from ancient organs to modern tissue patterns highlighted significant similarities, e.g., for miRNAs present in the muscle. Our first comprehensive analysis of microRNAs in ancient human tissues indicates that these stable molecules can be detected in tissue specimens after 5,300 years.

Genetic structure of the early Hungarian conquerors inferred from mtDNA haplotypes and Y-chromosome haplogroups in a small cemetery.

We applied ancient DNA methods to shed light on the origin of ancient Hungarians and their relation to modern populations. Hungarians moved into the Carpathian Basin from the Eurasian Pontic steppes in the year 895 AD as a confederation of seven tribes, but their further origin remains obscure. Here, we present 17 mtDNA haplotypes and four Y-chromosome haplogroups, which portray the genetic composition of an entire small cemetery of the first generation Hungarians. Using novel algorithms to compare these mitochondrial DNA haplogroups with other ancient and modern Eurasian data, we revealed that a significant portion of the Hungarians probably originated from a long ago consolidated gene pool in Central Asia-South Siberia, which still persists in modern Hungarians. Another genetic layer of the early Hungarians was obtained during their westward migrations by admixing with various populations of European origin, and an important component of these was derived from the Caucasus region. Most of the modern populations, which are genetically closest relatives of ancient Hungarians, today speak non-Indo-European languages. Our results contribute to our understanding of the peopling of Europe by providing ancient DNA data from a still genetically poorly studied period of medieval human migrations.

Population genomic analysis of ancient and modern genomes yields new insights into the genetic ancestry of the Tyrolean Iceman and the genetic structure of Europe.

Genome sequencing of the 5,300-year-old mummy of the Tyrolean Iceman, found in 1991 on a glacier near the border of Italy and Austria, has yielded new insights into his origin and relationship to modern European populations. A key finding of that study was an apparent recent common ancestry with individuals from Sardinia, based largely on the Y chromosome haplogroup and common autosomal SNP variation. Here, we compiled and analyzed genomic datasets from both modern and ancient Europeans, including genome sequence data from over 400 Sardinians and two ancient Thracians from Bulgaria, to investigate this result in greater detail and determine its implications for the genetic structure of Neolithic Europe. Using whole-genome sequencing data, we confirm that the Iceman is, indeed, most closely related to Sardinians. Furthermore, we show that this relationship extends to other individuals from cultural contexts associated with the spread of agriculture during the Neolithic transition, in contrast to individuals from a hunter-gatherer context. We hypothesize that this genetic affinity of ancient samples from different parts of Europe with Sardinians represents a common genetic component that was geographically widespread across Europe during the Neolithic, likely related to migrations and population expansions associated with the spread of agriculture.

NxrB encoding the beta subunit of nitrite oxidoreductase as functional and phylogenetic marker for nitrite-oxidizing Nitrospira.

Nitrospira are the most widespread and diverse known nitrite-oxidizing bacteria and key nitrifiers in natural and engineered ecosystems. Nevertheless, their ecophysiology and environmental distribution are understudied because of the recalcitrance of Nitrospira to cultivation and the lack of a molecular functional marker, which would allow the detection of Nitrospira in the environment. Here we introduce nxrB, the gene encoding subunit beta of nitrite oxidoreductase, as a functional and phylogenetic marker for Nitrospira. Phylogenetic trees based on nxrB of Nitrospira were largely congruent to 16S ribosomal RNA-based phylogenies. By using new nxrB-selective polymerase chain reaction primers, we obtained almost full-length nxrB sequences from Nitrospira cultures, two activated sludge samples, and several geographically and climatically distinct soils. Amplicon pyrosequencing of nxrB fragments from 16 soils revealed a previously unrecognized diversity of terrestrial Nitrospira with 1801 detected species-level operational taxonomic units (OTUs) (using an inferred species threshold of 95% nxrB identity). Richness estimates ranged from 10 to 946 coexisting Nitrospira species per soil. Comparison with an archaeal amoA dataset obtained from the same soils [Environ. Microbiol. 14: 525-539 (2012)] uncovered that ammonia-oxidizing archaea and Nitrospira communities were highly correlated across the soil samples, possibly indicating shared habitat preferences or specific biological interactions among members of these nitrifier groups.

Paleoproteomic study of the Iceman's brain tissue.

The Tyrolean Iceman, a Copper-age ice mummy, is one of the best-studied human individuals. While the genome of the Iceman has largely been decoded, tissue-specific proteomes have not yet been investigated. We studied the proteome of two distinct brain samples using gel-based and liquid chromatography-mass spectrometry-based proteomics technologies together with a multiple-databases and -search algorithms-driven data-analysis approach. Thereby, we identified a total of 502 different proteins. Of these, 41 proteins are known to be highly abundant in brain tissue and 9 are even specifically expressed in the brain. Furthermore, we found 10 proteins related to blood and coagulation. An enrichment analysis revealed a significant accumulation of proteins related to stress response and wound healing. Together with atomic force microscope scans, indicating clustered blood cells, our data reopens former discussions about a possible injury of the Iceman's head near the site where the tissue samples have been extracted.

Taxonize-gb: A tool for filtering GenBank non-redundant databases based on taxonomy.

Analyzing taxonomic diversity and identification in diverse ecological samples has become a crucial routine in various research and industrial fields. While DNA barcoding marker-gene approaches were once prevalent, the decreasing costs of next-generation sequencing have made metagenomic shotgun sequencing more popular and feasible. In contrast to DNA-barcoding, metagenomic shotgun sequencing offers possibilities for in-depth characterization of structural and functional diversity. However, analysis of such data is still considered a hurdle due to absence of taxa-specific databases. Here we present taxonize-gb, a command-line software tool to extract GenBank non-redundant nucleotide and protein databases, related to one or more input taxonomy identifier. Our tool allows the creation of taxa-specific reference databases tailored to specific research questions, which reduces search times and therefore represents a practical solution for researchers analyzing large metagenomic data on regular basis. Taxonize-gb is an open-source command-line Python-based tool freely available for installation at https://pypi.org/project/taxonize-gb/ and on GitHub https://github.com/msabrysarhan/taxonize_genbank. It is released under Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

Genetic Predisposition of Atherosclerotic Cardiovascular Disease in Ancient Human Remains.

Background: Several computed tomographic studies have shown the presence of atherosclerosis in ancient human remains. However, while it is important to understand the development of atherosclerotic cardiovascular disease (ASCVD), genetic data concerning the prevalence of the disease-associated single nucleotide polymorphisms (SNPs) in our ancestors are scarce. Objective: For a better understanding of the role of genetics in the evolution of ASCVD, we applied an enrichment capture sequencing approach to mummified human remains from different geographic regions and time periods. Methods: Twenty-two mummified individuals were analyzed for their genetic predisposition of ASCVD. Next-generation sequencing methods were applied to ancient DNA (aDNA) samples, including a novel enrichment approach specifically designed to capture SNPs associated with ASCVD in genome-wide association studies of modern humans. Findings: Five out of 22 ancient individuals passed all filter steps for calculating a weighted polygenic risk score (PRS) based on 87 SNPs in 56 genes. PRSs were correlated to scores obtained from contemporary people from around the world and cover their complete range. The genetic results of the ancient individuals reflect their phenotypic results, given that the only two mummies showing calcified atherosclerotic arterial plaques on computed tomography scans are the ones exhibiting the highest calculated PRSs. Conclusions: These data show that alleles associated with ASCVD have been widespread for at least 5,000 years. Despite some limitations due to the nature of aDNA, our approach has the potential to lead to a better understanding of the interaction between environmental and genetic influences on the development of ASCVD.

First direct dating of the Late Neanderthal remains from Subalyuk Cave in Northern Hungary.

The Subalyuk hominin remains were uncovered in 1932 in a cave of the same name in the Bükk Mountains, near the village of Cserépfalu in Borsod-Abaúj-Zemplén County, Northern Hungary. The remains represent two individuals, an adult and a young child who have been described in a few publications since their discovery, providing substantial anthropological data and general assessments of their Neanderthal affiliation. They were associated with Late Mousterian industry. Thus, the Bükk Mountains gain importance in the discussion concerning the contribution of East Central European sites to the debate on the peopling history of Europe during the Late Middle to Early Upper Palaeolithic transition. In this paper, we summarize the archaeological and chronological context of the two individuals, and publish the first direct dating results that place them among the Last Neanderthals of Central Europe.

Evidence for dynastic succession among early Celtic elites in Central Europe.

The early Iron Age (800 to 450 BCE) in France, Germany and Switzerland, known as the 'West-Hallstattkreis', stands out as featuring the earliest evidence for supra-regional organization north of the Alps. Often referred to as 'early Celtic', suggesting tentative connections to later cultural phenomena, its societal and population structure remain enigmatic. Here we present genomic and isotope data from 31 individuals from this context in southern Germany, dating between 616 and 200 BCE. We identify multiple biologically related groups spanning three elite burials as far as 100 km apart, supported by trans-regional individual mobility inferred from isotope data. These include a close biological relationship between two of the richest burial mounds of the Hallstatt culture. Bayesian modelling points to an avuncular relationship between the two individuals, which may suggest a practice of matrilineal dynastic succession in early Celtic elites. We show that their ancestry is shared on a broad geographic scale from Iberia throughout Central-Eastern Europe, undergoing a decline after the late Iron Age (450 BCE to ~50 CE).

A Nitrospira metagenome illuminates the physiology and evolution of globally important nitrite-oxidizing bacteria.

Nitrospira are barely studied and mostly uncultured nitrite-oxidizing bacteria, which are, according to molecular data, among the most diverse and widespread nitrifiers in natural ecosystems and biological wastewater treatment. Here, environmental genomics was used to reconstruct the complete genome of "Candidatus Nitrospira defluvii" from an activated sludge enrichment culture. On the basis of this first-deciphered Nitrospira genome and of experimental data, we show that Ca. N. defluvii differs dramatically from other known nitrite oxidizers in the key enzyme nitrite oxidoreductase (NXR), in the composition of the respiratory chain, and in the pathway used for autotrophic carbon fixation, suggesting multiple independent evolution of chemolithoautotrophic nitrite oxidation. Adaptations of Ca. N. defluvii to substrate-limited conditions include an unusual periplasmic NXR, which is constitutively expressed, and pathways for the transport, oxidation, and assimilation of simple organic compounds that allow a mixotrophic lifestyle. The reverse tricarboxylic acid cycle as the pathway for CO2 fixation and the lack of most classical defense mechanisms against oxidative stress suggest that Nitrospira evolved from microaerophilic or even anaerobic ancestors. Unexpectedly, comparative genomic analyses indicate functionally significant lateral gene-transfer events between the genus Nitrospira and anaerobic ammonium-oxidizing planctomycetes, which share highly similar forms of NXR and other proteins reflecting that two key processes of the nitrogen cycle are evolutionarily connected.

Tuberculosis in mummies - New findings, perspectives and limitations.

The molecular analysis of ancient pathogen DNA represents a unique opportunity for the study of infectious diseases in ancient human remains. Among other diseases, paleogenetic studies have been successful in detecting tuberculous DNA in ancient human remains. In the beginning of ancient DNA (aDNA) studies, the presence of tuberculosis (TB) DNA was assessed using a PCR-based assay targeting specific regions of the Mycobacterium tuberculosis (MTB) complex, such as the repetitive element IS6110. The advent of high-throughput sequencing has enabled the reconstruction of full ancient TB genomes in the field of paleomicrobiology. However, despite the numerous paleopathological and PCR-based studies on the presence of tuberculosis in historic human remains, full genome wide reconstructions are still limited to well-preserved specimens with low environmental contamination and connected with extensive screening efforts. This has led to some controversies regarding the evolutionary history of its causative agent Mycobacterium tuberculosis. In this context, mummies have been shown to be a good source for the detection of MTB complex DNA due to a low exposure to environmental influences and the overall good state of preservation of hard and soft tissues in the human remains. Here, we present the major findings on the presence of TB infections in the 18th century naturally mummified human remains from Vác, Hungary and the current status of the detection of MTB complex DNA in mummified human remains. The future perspectives of detecting tuberculosis in mummies will be discussed in the light of methodological aspects, as well as ethical and curational challenges.

Ancestry and kinship in a Late Antiquity-Early Middle Ages cemetery in the Eastern Italian Alps.

In South Tyrol (Eastern Italian Alps), during Late Antiquity-Early Middle Ages, archeological records indicate cultural hybridization among alpine groups and peoples of various origin. Using paleogenomics, we reconstructed the ancestry of 20 individuals (4th-7th cent. AD) from a cemetery to analyze whether they had heterogeneous or homogeneous ancestry and to study their social organization. The results revealed a primary genetic ancestry from southern Europe and additional ancestries from south-western, western, and northern Europe, suggesting that cultural hybridization was accompanied by complex genetic admixture. Kinship analyses found no genetic relatedness between the only two individuals buried with grave goods. Instead, a father-son pair was discovered in one multiple grave, together with unrelated individuals and one possible non-local female. These genetic findings indicate the presence of a high social status familia, which is supported by the cultural materials and the proximity of the grave to the most sacred area of the church.

High-coverage genome of the Tyrolean Iceman reveals unusually high Anatolian farmer ancestry.

The Tyrolean Iceman is known as one of the oldest human glacier mummies, directly dated to 3350-3120 calibrated BCE. A previously published low-coverage genome provided novel insights into European prehistory, despite high present-day DNA contamination. Here, we generate a high-coverage genome with low contamination (15.3×) to gain further insights into the genetic history and phenotype of this individual. Contrary to previous studies, we found no detectable Steppe-related ancestry in the Iceman. Instead, he retained the highest Anatolian-farmer-related ancestry among contemporaneous European populations, indicating a rather isolated Alpine population with limited gene flow from hunter-gatherer-ancestry-related populations. Phenotypic analysis revealed that the Iceman likely had darker skin than present-day Europeans and carried risk alleles associated with male-pattern baldness, type 2 diabetes, and obesity-related metabolic syndrome. These results corroborate phenotypic observations of the preserved mummified body, such as high pigmentation of his skin and the absence of hair on his head.

Hit or miss - A metagenomic evaluation of intra-bone variability of host pathogen load in tuberculosis-infected human remains.

Many sampling protocols have been established to successfully retrieve human DNA from archaeological remains, however the systematic detection of ancient pathogens remains challenging. Here, we present a first assessment of the intra-bone variability of metagenomic composition in human skeletal remains and its effect on the sampling success for Mycobacterium tuberculosis (MTB) and human endogenous DNA. For this purpose, four bone samples from published peer-reviewed studies with PCR-based evidence for ancient MTB DNA were selected. Two bone samples of a Neolithic individual from Halberstadt, Germany and two ribs of two 18th-century Hungarian church mummies were sampled at multiple locations for equal amounts, followed by DNA extraction and library construction. Shotgun sequencing data was generated for taxonomic profiling as well as quantitative and qualitative evaluation of MTB and human endogenous DNA. Despite low variance in microbial diversity within and across samples, intra-bone variability of up to 36.45- and 62.88-fold for authentic ancient MTB and human reads, respectively, was detected. This study demonstrates the variable sampling success for MTB and human endogenous DNA within single skeletal samples despite relatively consistent microbial composition and highlights how a multisampling approach can facilitate the detection of hotspots with highly concentrated pathogen and human endogenous DNA.

Re-examination of the Subalyuk Neanderthal remains uncovers signs of probable TB infection (Subalyuk Cave, Hungary).

In 1932, skeletal remains of two Neanderthal individuals, a young adult female and a 3-4-year-old child, were discovered in Subalyuk Cave in Northern Hungary [1,2]. Results of the anthropological examination were published some years after this important discovery. Methodological progress encouraged re-examination of the material during the last few years. Radiocarbon dating revealed a chronological age of 39,732-39,076 cal. BP for the adult female and 36,117-35,387 cal. BP for the child [3]. Morphological paleopathological studies of these Neanderthal remains uncovered distinct evidence of skeletal infections. Alterations of the adult individual's sacrum suggest probable early-stage sacroiliitis, while several vertebral bodies indicate superficial osseous remodelling of infectious origin. Traces of pathological lesions were observed on the endocranial surface of the child's skull, reflecting a reaction of meningeal tissues, a consequence of a probable TB-related meningeal infectious process. Results of recent paleomicrobiological examinations - lipid biomarker and aDNA studies - support the morphological diagnosis of probable TB infections [4].