José Horacio Grau’s research while affiliated with Museum für Naturkunde - Leibniz Institute for Research on Evolution and Biodiversity and other places

The molecular processes underlying genome exclusion and clonal gamete formation in the germline of hybridogenetic water frog hybrids are poorly understood. For the first time, we have characterized the coding sequences of 160 gametogenic genes from the European water frog species Pelophylax lessonae (LL) and Pelophylax ridibundus (RR). In addition, single nucleotide polymorphisms (SNPs) in 52 of these genes were analyzed in both species (60 LL, 252 RR) and their hybridogenetic hybrid, Pelophylax esculentus (340 LR), from population systems that differ in genotypic composition, sex ratio, and modes of inheritance. Ten gametogenic genes may be linked to the population system and, thus, indirectly to the reproductive mode, i.e., the premeiotic exclusion of the ridibundus (R) genome in the lessonae - esculentus system and/or the lessonae (L) genome in the ridibundus - esculentus system. These genes are involved in various processes, including the control of spindle formation and chromosome movement during mitosis and meiosis, epigenetic silencing, cell cycle regulation, double-strand break repair and homologous recombination, including transposable element silencing. In addition, both the transcriptome and SNP data provide evidence for gene flow between the L and R genomes. The results are consistent with the clonal inheritance patterns described for P. esculentus and suggest that genome exclusion is based on complex genomic interactions involving multiple genes and molecular factors. Furthermore, our data suggest that interspecific gene flow has played an important role in the evolution of different inheritance modes in P. esculentus , leading to the emergence of distinct population systems.

Advances in high-throughput sequencing (HTS) have made it a powerful resource for the conservation of threatened species, providing information at both population and individual levels to inform management decisions. In South America, however, the application of HTS in conservation has been limited, primarily due to challenges in funding and access to advanced genomic equipment and analytical expertise. Darwin’s fox ( Lycalopex fulvipes ), endemic to Chile’s Valdivian Temperate Rainforest, is the most endangered canid in South America with a small and declining population estimated at less than 1000 mature individuals. Despite its endangered status, significant knowledge gaps remain. Here we highlight the potential of HTS to address these challenges, such as clarifying its taxonomy, demographic history, geographic distribution, population structure, genetic diversity, and pathogen exposure. Integrating molecular data into conservation planning will be pivotal in ensuring the long-term survival of Darwin’s fox by identifying priorities for targeted management interventions, highlighting areas of critical habitat for conservation, and guiding genetic rescue efforts to enhance genetic diversity and resilience.

Wastewater-based surveillance (WBS) is a proven tool for monitoring population-level infection events. Wastewater contains high concentrations of inhibitors, which contaminate the total nucleic acids (TNA) extracted from these samples. We found that TNA extracts from raw influent of Berlin wastewater treatment plants contained highly variable amounts of inhibitors that impaired molecular analyses like dPCR and next-generation sequencing (NGS). By using dilutions, we were able to detect inhibitory effects. To enhance WBS sensitivity and stability, we applied a combination of PCR inhibitor removal and TNA dilution (PIR+D). This approach led to a 26-fold increase in measured SARS-CoV-2 concentrations, practically reducing the detection limit. Additionally, we observed a substantial increase in the stability of the time series. We define suitable stability as a mean absolute error (MAE) below 0.1 log10 copies/L and a geometric mean relative absolute error (GMRAE) below 26%. Using PIR+D, the MAE could be reduced from 0.219 to 0.097 and the GMRAE from 65.5% to 26.0%, and even further in real-world WBS. Furthermore, PIR+D improved SARS-CoV-2 genome alignment and coverage in amplicon-based NGS for low to medium concentrations. In conclusion, we strongly recommend both the monitoring and removal of inhibitors from samples for WBS.

The importance of COVID-19 surveillance from wastewater continues to grow since case-based surveillance in the general population has been scaled back world-wide. In Berlin, Germany, quantitative and genomic wastewater monitoring for SARS-CoV-2 is performed in three wastewater treatment plants (WWTP) covering 84% of the population since December 2021. The SARS-CoV-2 Omicron sublineage JN.1 (B.2.86.1.1), was first identified from wastewater on 22 October 2023 and rapidly became the dominant sublineage. This change was accompanied by a parallel and still ongoing increase in the notification-based 7-day-hospitalization incidence of COVID-19 and COVID-19 ICU utilization, indicating increasing COVID-19 activity in the (hospital-prone) population and a higher strain on the healthcare system. In retrospect, unique mutations of JN.1 could be identified in wastewater as early as September 2023 but were of unknown relevance at the time. The timely detection of new sublineages in wastewater therefore depends on the availability of new sequences from GISAID and updates to Pango lineage definitions and Nextclade. We show that genomic wastewater surveillance provides timely public health evidence on a regional level, complementing the existing indicators.

Hybridization and introgression have played important roles in the history of various species, including lineage diversification and the evolution of adaptive traits. Hybridization can accelerate the development of reproductive isolation between diverging species, and thus valuable insight into the evolution of reproductive barrier formation may be gained by studying secondary contact zones. Hedgehogs of the genus Erinaceus, which are insectivores sensitive to changes in climate, are a pioneer model in Pleistocene phylogeography. The present study provides the first genome-wide SNP data regarding the Erinaceus hedgehogs species complex, offering a unique comparison of two secondary contact zones between Erinaceus europaeus and E. roumanicus. Results confirmed diversification of the genus during the Pleistocene period, and detected a new refugial lineage of E. roumanicus outside the Mediterranean basin, most likely in the Ponto-Caspian region. In the Central European zone, the level of hybridization was low, whereas in the Russian-Baltic zone, both species hybridise extensively. Asymmetrical gene flow from E. europaeus to E. roumanicus suggests that reproductive isolation varies according to the direction of the crosses in the hybrid zones. However, no loci with significantly different patterns of introgression were detected. Markedly different pre- and post-zygotic barriers, and thus diverse modes of species boundary maintenance in the two contact zones, likely exist. This pattern is probably a consequence of the different age and thus of the different stage of evolution of reproductive isolating mechanisms in each hybrid zone.

The use of RNA sequencing from wastewater samples is a valuable way for estimating infection dynamics and circulating lineages of SARS-CoV-2. This approach is independent from testing individuals and can therefore become the key tool to monitor this and potentially other viruses. However, it is equally important to develop easily accessible and scalable tools which can highlight critical changes in infection rates and dynamics over time across different locations given sequencing data from wastewater. Here, we provide an analysis of lineage dynamics in Berlin and New York City using wastewater sequencing and present PiGx SARS-CoV-2, a highly reproducible computational analysis pipeline with comprehensive reports. This end-to-end pipeline includes all steps from raw data to shareable reports, additional taxonomic analysis, deconvolution and geospatial time series analyses. Using simulated datasets (in silico generated and spiked-in samples) we could demonstrate the accuracy of our pipeline calculating proportions of Variants of Concern (VOC) from environmental as well as pre-mixed samples (spiked-in). By applying our pipeline on a dataset of wastewater samples from Berlin between February 2021 and January 2022, we could reconstruct the emergence of B.1.1.7(alpha) in February/March 2021 and the replacement dynamics from B.1.617.2 (delta) to BA.1 and BA.2 (omicron) during the winter of 2021/2022. Using data from very-short-reads generated in an industrial scale setting, we could see even higher accuracy in our deconvolution. Lastly, using a targeted sequencing dataset from New York City (receptor-binding-domain (RBD) only), we could reproduce the results recovering the proportions of the so-called cryptic lineages shown in the original study. Overall our study provides an in-depth analysis reconstructing virus lineage dynamics from wastewater. While applying our tool on a wide range of different datasets (from different types of wastewater sample locations and sequenced with different methods), we show that PiGx SARS-CoV-2 can be used to identify new mutations and detect any emerging new lineages in a highly automated and scalable way. Our approach can support efforts to establish continuous monitoring and early-warning projects for detecting SARS-CoV-2 or any other pathogen.

The core microbiome, which refers to a set of consistent microbial features across populations, is of major interest in microbiome research and has been addressed by numerous studies. Understanding the core microbiome can help identify elements that lead to dysbiosis, and lead to treatments for microbiome-related health states. However, defining the core microbiome is a complex task at several levels. In this review, we consider the current state of core human microbiome research. We consider the knowledge that has been gained, the factors limiting our ability to achieve a reliable description of the core human microbiome, and the fields most likely to improve that ability. DNA sequencing technologies and the methods for analyzing metagenomics and amplicon data will most likely facilitate higher accuracy and resolution in describing the microbiome. However, more effort should be invested in characterizing the microbiome’s interactions with its human host, including the immune system and nutrition. Other components of this holobiontic system should also be emphasized, such as fungi, protists, lower eukaryotes, viruses, and phages. Most importantly, a collaborative effort of experts in microbiology, nutrition, immunology, medicine, systems biology, bioinformatics, and machine learning is probably required to identify the traits of the core human microbiome.

The use of RNA sequencing from wastewater samples is a valuable way for estimating infection dynamics and circulating lineages of SARS-CoV-2. This approach is independent from testing individuals and can therefore become the key tool to monitor this and potentially other viruses. However, it is equally important to develop easily accessible and scalable tools which can highlight critical changes in infection rates and dynamics over time across different locations given sequencing data from wastewater. Here, we provide an analysis of lineage dynamics in Berlin and New York City using wastewater sequencing and present PiGx SARS-CoV-2, a highly reproducible computational analysis pipeline with comprehensive reports. This end-to-end pipeline includes all steps from raw data to shareable reports, additional taxonomic analysis, deconvolution and geospatial time series analyses. Using simulated datasets (in silico generated and spiked-in samples) we could demonstrate the accuracy of our pipeline calculating proportions of Variants of Concern (VOC) from environmental as well as pre-mixed samples (spiked-in).

The paper describes the new land planarian genus Mapuplana gen. nov. from Chile, on the basis of the two new species Mapuplana guttulata sp. nov. and M. fjordica sp. nov. The genus Mapuplana is mainly characterised by two putative apomorphies: a subneural parenchymal musculature consisting of diagonal decussate muscle fibres; and a blind duct opening sideways into the female atrium. The new species are very similar to each other in their general anatomy and differ only in details in the pattern of dorsal colouration, the relative distance between mouth and gonopore, the relative thickness of the ventral cutaneous musculature, the orientation of the gonoduct, and the shape of the female atrium. http://www.zoobank.org/urn:lsid:zoobank.org:pub:120AC180-D4AC-433F-B3A0-BB96C6962DB4