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13 Nov 2024
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Re-annotation of SARS-CoV-2 proteins using an HHpred-based approach opens new opportunities for a better understanding of this virus

Leveraging HHpred with rigorous validation for improved detection of host-virus homologies

Recommended by ORCID_LOGO based on reviews by 2 anonymous reviewers

The assessment by Brézellec (2024) of the quality of HHpred-based SARS-CoV-2 protein annotations against the traditional Pfam annotations is highly justified and valuable. HHpred’s ability to detect remote homologies offers an expanded view of viral protein similarities, potentially uncovering subtle functional mimicries that Pfam may miss due to its sensitivity limitations when dealing with divergent sequences. However, the accuracy and specificity of HHpred results can be compromised by false positives, especially when dealing with complex viral proteins that feature transmembrane or low-complexity regions prone to spurious matches.

To address this, the author made a thoughtful decision to implement a multi-step validation protocol. This approach included establishing progressively lower probability thresholds to capture weaker but biologically plausible hits, and organizing hits into “families” of similarly located alignments to validate the robustness of matches. They also cross-verified results by running SARS-CoV-2 protein queries against non-human proteomes (plants, fruit flies, bacteria, and archaea), allowing them to discern between biologically meaningful matches and potentially random alignments. By adding manual verification with InterPro domain annotations, the authors took additional steps to ensure that identified similarities were not only statistically significant but also biologically relevant.

This rigorous validation strategy adds a layer of reliability to HHpred results, demonstrating an effective maximization of sensitivity while maintaining specificity. This approach yielded biologically intriguing and previously undocumented similarities, such as between the Spike-prominin and ORF3a-GPCR, underscoring the quality and depth of the annotation process. These findings highlight a pathway for further experimental validation and illustrate the potential of HHpred to contribute high-quality insights when applied with careful quality control measures.

In summary, the decision to adopt HHpred (Gabler et al. 2020) and enhance its outputs with a robust quality validation process not only improved the depth of SARS-CoV-2 protein annotations but also established a high standard for future viral annotation projects, striking an effective balance between discovery potential and annotation quality​. The authors have conducted a study that is methodologically rigorous, well-detailed, and highly pertinent to the field. This work stands as a significant contribution to the scientific community, providing resources and insights that are likely to guide future research in this area. 

              
References

Brézellec, P (2024) Re-annotation of SARS-CoV-2 proteins using an HHpred-based approach opens new opportunities for a better understanding of this virus. bioRxiv, ver. 3 peer-reviewed and recommended by PCI Genomics. https://doi.org/10.1101/2023.06.06.543855

Gabler F, Nam S-Z, Till S, Mirdita M, Steinegger M, Söding J, Lupas AN, Alva V (2020) Protein Sequence Analysis Using the MPI Bioinformatics Toolkit. Current Protocols in Bioinformatics, 72, e108. https://doi.org/10.1002/cpbi.108

 

Re-annotation of SARS-CoV-2 proteins using an HHpred-based approach opens new opportunities for a better understanding of this virusPierre Brézellec<p>Since the publication of the genome of SARS-CoV-2 – the causative agent of COVID-19 – in January 2020, many bioinformatic tools have been applied to annotate its proteins. Although efficient methods have been used, such as the identification of...Bioinformatics, Evolutionary genomics, Viruses and transposable elementsJitendra Narayan2023-06-08 10:17:04 View
11 May 2024
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The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics

Informed Choices, Cohesive Future: Decisions and Recommendations for ERGA

Recommended by ORCID_LOGO based on reviews by Justin Ideozu and Eric Crandall

The European Reference Genome Atlas (ERGA) (Mc Cartney et al, 2024, Mazzoni et al, 2023) demonstrates the collaborative spirit and intellectual abilities of researchers from 33 European countries. This ambitious project, which is part of the Earth BioGenome Project (Lewin et al., 2018) Phase II, has embarked on an unprecedented mission: to decipher the genetic makeup of 150,000 species over a span of four years. At the heart of ERGA is a decentralized pilot infrastructure specifically built to assist the production of high-quality reference genomes. This structure acts as a scaffold for the massive task of genome sequencing, giving the necessary framework to manage the complexity of genomic research. The research paper under consideration offers a comprehensive narrative of ERGA's evolution, outlining both successes and challenges encountered along the road. 

One of the most significant issues addressed in the manuscript is the equitable distribution of resources and expertise among participating laboratories and countries. In a project of this magnitude, it is critical to leverage the pooled talents and capacities of researchers from across Europe. ERGA's pan-European network promotes communications and collaboration, creating an environment in which knowledge flows freely and barriers are overcome. This adoption of strong coordination and communication tactics will be essential to ERGA's success. Scientific collaboration depends on efficient communication channels because they allow researchers to share resources, collaborate on new initiatives, and exchange ideas. Through a diverse range of gatherings, courses, and virtual discussion boards, ERGA fosters an environment of transparency and cooperation among members, enabling scientists to overcome challenges and make significant discoveries. The importance ERGA places on training and information transfer programmes is a pillar of its strategy. Understanding the importance of capacity development, ERGA invests in providing researchers with the knowledge and abilities necessary for effectively navigating the complicated terrain of genomic research. A wide range of subjects are covered in training programmes (Larivière et al. 2023), from sample preparation and collection to data processing methods and sequencing technology. Through the development of a group of highly qualified experts, ERGA creates the foundation for continued advancement and creativity in the genomics sector.

This manuscript also covers in detail the technological workflows and sequencing techniques used in ERGA's pilot infrastructure. With the aid of cutting-edge sequencing technologies based on both long-read and short-read sequencing, they are working to unravel the complex structure of the genetic code with a level of accuracy and precision never before possible. To guarantee the accuracy of genetic data and prevent mistakes and flaws that can jeopardize the findings' integrity, quality control methods are put in place. Despite having a focus on genome sequencing due to its technological complexities, ERGA also remains firm in its dedication to metadata collection and sample validation. Metadata serves as a critical link between raw genetic data and useful scientific insights, giving necessary context and allowing researchers to draw practical findings from their investigations. Sample validation approaches improve the reliability and reproducibility of the results, providing users confidence in the quality of the genetic data provided by ERGA.​

Looking ahead, ERGA envisions its decentralized infrastructure serving as a model for global collaborative research efforts. By embracing diversity, encouraging cooperation, and pushing for open access to data and resources, ERGA hopes to catalyze scientific discovery and generate positive change in the field of biodiversity genomics. ERGA aims to promote a more equitable and sustainable future for all by ongoing interaction with stakeholders, intensive outreach and education activities, and policy change advocacy. In addition to its immediate goals, ERGA considers the long-term implications of its work. As genomic technology progresses, the potential application of high-quality reference genomes will continue to grow. From informing conservation efforts and illuminating evolutionary histories to revolutionizing healthcare and agriculture, it is likely that ERGA's contributions will have far-reaching consequences for people and the planet as a whole.​

Furthermore, ERGA understands the importance of interdisciplinary collaboration in addressing the difficult challenges of the twenty-first century. ERGA aims to integrate genetic research into larger initiatives to promote sustainability and biodiversity conservation by forming relationships with stakeholders from other areas, such as policymakers, conservationists, and indigenous groups. Through shared knowledge and community action, ERGA seeks to create a future in which mankind coexists peacefully with the natural world, guided by a thorough grasp of its genetic legacy and ecological interconnectivity.

Finally, the manuscript exemplifies ERGA's collaborative ambitions and achievements, capturing the spirit of creativity and collaboration that defines this ground-breaking effort. As ERGA continues to push the boundaries of genetic research, it remains dedicated to scientific excellence, inclusivity, and the quest of knowledge for the benefit of society. I wholeheartedly recommend the publication of this groundbreaking initiative, offering my enthusiastic endorsement for its valuable contribution to the scientific community.​​

References
Larivière, D., Abueg, L., Brajuka, N. et al. (2024). Scalable, accessible and reproducible reference genome assembly and evaluation in Galaxy. Nature Biotechnology 42, 367-370. https://doi.org/10.1038/s41587-023-02100-3

Lewin, H. A., Robinson, G. E., Kress, W. J., Baker, W. J., Coddington, J., Crandall, K. A., Durbin, R., Edwards, S. V., Forest, F., Gilbert, M. T. P., Goldstein, M. M., Grigoriev, I. V., Hackett, K. J., Haussler, D., Jarvis, E. D., Johnson, W. E., Patrinos, A., Richards, S., Castilla-Rubio, J. C., … Zhang, G. (2018). Earth BioGenome Project: Sequencing life for the future of life. Proceedings of the National Academy of Sciences, 115(17), 4325–4333. https://doi.org/10.1073/pnas.1720115115

Mazzoni, C. J., Claudio, C.i, Waterhouse, R. M. (2023). Biodiversity: an atlas of European reference genomes. Nature 619 : 252-252. https://doi.org/10.1038/d41586-023-02229-w

Mc Cartney, A. M., Formenti, G., Mouton, A., Panis, D. de, Marins, L. S., Leitão, H. G., Diedericks, G., Kirangwa, J., Morselli, M., Salces-Ortiz, J., Escudero, N., Iannucci, A., Natali, C., Svardal, H., Fernández, R., Pooter, T. de, Joris, G., Strazisar, M., Wood, J., … Mazzoni, C. J. (2024). The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics. bioRxiv, ver. 4 peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2023.09.25.559365

The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomicsAnn M Mc Cartney, Giulio Formenti, Alice Mouton, Claudio Ciofi, Robert M Waterhouse, Camila J Mazzoni, Diego De Panis, Luisa S Schlude Marins, Henrique G Leitao, Genevieve Diedericks, Joseph Kirangwa, Marco Morselli, Judit Salces, Nuria Escudero, ...<p>English: A global genome database of all of Earth's species diversity could be a treasure trove of scientific discoveries. However, regardless of the major advances in genome sequencing technologies, only a tiny fraction of species have genomic...Bioinformatics, ERGA PilotJitendra Narayan Justin Ideozu, Eric Crandall2023-10-01 01:03:58 View
03 Sep 2024
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A chromosome-level, haplotype-resolved genome assembly and annotation for the Eurasian minnow (Leuciscidae: Phoxinus phoxinus) provide evidence of haplotype diversity

Exploring evolutionary adaptations through Phoxinus phoxinus genomics

Recommended by ORCID_LOGO based on reviews by Alice Dennis and 2 anonymous reviewers

Oriowo et al. (2024) offer a thorough and meticulously conducted study that makes a substantial contribution to our understanding of the Eurasian minnow (Phoxinus phoxinus), particularly in terms of its genetic diversity, structural variations, and evolutionary adaptations. The authors have achieved an impressive feat by generating an annotated haplotype-phased, chromosome-level genome assembly (2n = 50). This was accomplished through the integration of high-fidelity long reads with chromosome conformation capture data (Hi-C), resulting in a highly complete and accurate genome assembly. The assembly is characterized by a haploid size of 940 Megabase pairs (Mbp) for haplome one and 929 Mbp for haplome two, with scaffold N50 values of 36.4 Mb and 36.6 Mb, respectively. These metrics, alongside BUSCO scores of 96.9% and 97.2%, highlight the high quality of the genome, making it a robust foundation for further genetic exploration and analyses.

The study’s findings are both novel and significant, providing deep insights into the genetic architecture of P. phoxinus. The authors report heterozygosity rate of 1.43% and a high repeat content of approximately 54%, primarily consisting of DNA transposons. These transposons play a crucial role in genome rearrangements and variations, contributing to the species' adaptability and evolution (Bourque et al. 2018). The research also identifies substantial structural variations within the genome, including insertions, deletions, inversions, and translocations (Oriowo et al. 2024). Beyond these findings, the genome annotation is exceptionally comprehensive, containing 30,980 mRNAs and 23,497 protein-coding genes. The study’s gene family evolution analysis, which compares the P. phoxinus proteome to that of ten other teleost species, reveals immune system gene families that favor histone-based disease prevention mechanisms over NLR-based immune responses. This provides new insight into the evolutionary strategies that have emerged in P. phoxinus, enabling its survival in its environment. Moreover, the demographic analysis conducted in the study reveals historical fluctuations in the effective population size of P. phoxinus, likely correlated with past climatic changes, offering insights into the species' evolutionary history.

This annotated and phased reference genome not only serves as a crucial resource for resolving taxonomic complexities within the genus Phoxinus but also highlights the importance of haplotype-phased assemblies in understanding genetic diversity, particularly in species characterized by high heterozygosity. The authors have delivered a study that is methodologically sound, richly detailed, and highly relevant to the field. The study represents a valuable and impactful contribution to the scientific community, offering resources and knowledge that will likely inform future research in the field.

              

References

Bourque G, Burns KH, Gehring M, Gorbunova V, Seluanov A, Hammell M, Imbeault M, Izsvák Z, Levin HL, Macfarlan TS, Mager DL, Feschotte C (2018) Ten things you should know about transposable elements. Genome Biology, 19, 199. https://doi.org/10.1186/s13059-018-1577-z

Oriowo TO, Chrysostomakis I, Martin S, Kukowka S, Brown T, Winkler S, Myers EW, Böhne A, Stange M (2024) A chromosome-level, haplotype-resolved genome assembly and annotation for the Eurasian minnow (Leuciscidae: Phoxinus phoxinus) provide evidence of haplotype diversity. bioRxiv, ver. 6 peer-reviewed and recommended by PCI Genomics https://doi.org/10.1101/2023.11.30.569369

A chromosome-level, haplotype-resolved genome assembly and annotation for the Eurasian minnow (Leuciscidae: *Phoxinus phoxinus*) provide evidence of haplotype diversityTemitope O. Oriowo, Ioannis Chrysostomakis, Sebastian Martin, Sandra Kukowka, Thomas Brown, Sylke Winkler, Eugene W. Myers, Astrid Boehne, Madlen Stange<p>In this study we present an in-depth analysis of the Eurasian minnow (<em>Phoxinus phoxinus</em>) genome, highlighting its genetic diversity, structural variations, and evolutionary adaptations. We generated an annotated haplotype-phased, chrom...Evolutionary genomics, Structural genomics, VertebratesJitendra Narayan Henrik Lanz, Rui Borges, Fergal Martin, Vinod Scaria, Mihai Pop, Alice Dennis, Jin-Wu Nam, Monya Baker, Giuseppe Narzisi2023-12-04 14:49:17 View
14 Jan 2025
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Chromosome-level reference genome assembly for the mountain hare (Lepus timidus)

The genomic foundations of adaptation: evaluating the mountain hare

Recommended by ORCID_LOGO based on reviews by Theodore Squires and 1 anonymous reviewer

Fekete et al. (2024) generated a chromosome-level reference genome assembly for the mountain hare (Lepus timidus). This represents a significant advancement in genomic research for non-model organisms, achieving high quality through advanced sequencing and curation techniques. This achievement serves as a foundational blueprint for future efforts in other species, particularly those with ecological or evolutionary importance. The assembly has high continuity and completeness, with an N50 scaffold length of 125.8 Mb and a contig N50 of 4.9 Mb, meeting the Earth BioGenome Project's stringent criteria for reference-grade genomes (Mc Cartney et al., 2024). The combination of PacBio HiFi sequencing and Hi-C scaffolding techniques enabled robust assembly and chromosomal scaffolding of all 23 autosomes and the X and Y sex chromosomes. Additionally, manual curation enhanced the assembly quality, accurately representing genomic sequences. Although the genome provides valuable structural insights, the limited functional annotations highlight a need for further investigation into the genetic underpinnings of the ecological and adaptive traits of the mountain hare.

The ecological and evolutionary implications of resolving this genome are considerable, particularly given the mountain hare’s adaptations to cold, snowy environments and its role in boreal ecosystems. The assembly facilitates the study of adaptations, such as camouflage and snowshoe-like feet, which are critical for survival in its rapidly changing habitat. Comparative genomic analyses reveal the evolutionary relationship between Lepus timidus and closely related species, such as the brown hare (L. europaeus) and Irish hare (L. t. hibernicus), providing insights into gene flow, hybridization, and speciation. These findings have practical implications for conservation genetics, particularly for subspecies threatened by habitat loss and climate change. However, the study does not identify specific adaptive loci or functional variants, limiting its immediate applicability to understanding the molecular basis of traits crucial for survival in extreme environments. Expanding the functional annotation of this genome would significantly enhance its utility in conservation and ecological genomics. Moreover, the high repetitive element content (42.35%) underscores the need for detailed annotation to facilitate downstream studies. These issues suggest that additional refinement and validation are warranted. Despite these limitations, the assembly is invaluable for studying genetic adaptations, hybridization, and hare conservation. Future research should focus on functional annotation, population-level comparisons, and targeted studies of ecological traits to fully realize the potential of this high-quality reference genome.

             

References

Fekete Z, Absolon DE, Michell C, Wood JMD, Goffart S, Pohjoismäki JLO (2024) Chromosome-level reference genome assembly for the mountain hare (Lepus timidus). bioRxiv, ver. 2 peer-reviewed and recommended by PCI Genomics. https://doi.org/10.1101/2024.06.10.598177

Mc Cartney AM, Formenti G, Mouton A, De Panis D, Marins LS, Leitão HG, Diedericks G, Kirangwa J, Morselli M, Salces-Ortiz J, Escudero N, Iannucci A, Natali C, Svardal H, Fernández R, De Pooter T, Joris G, Strazisar M, Wood JMD, Herron KE, …, Mazzoni CJ (2024) The European Reference Genome Atlas: piloting a decentralised approach to equitable biodiversity genomics. npj Biodiversity, 3, 28. https://doi.org/10.1038/s44185-024-00054-6

 

Chromosome-level reference genome assembly for the mountain hare (*Lepus timidus*)Zsofia Fekete, Dominic E. Absolon, Craig Michell, Jonathan M. D. Wood, Steffi Goffart, Jaakko L. O. Pohjoismaki<p>&nbsp;We present here a high-quality genome assembly of a male mountain hare (<em>Lepus timidus</em> Linnaeus), from Ilomantsi, Eastern Finland, utilizing an isolated fibroblast cell line as the source for high quality DNA and RNA. Following th...Bioinformatics, ERGA Pilot, Evolutionary genomics, VertebratesJitendra Narayan2024-06-11 08:52:32 View
07 Sep 2023
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The demographic history of the wild crop relative Brachypodium distachyon is shaped by distinct past and present ecological niches

Natural variation and adaptation in Brachypodium distachyon

Recommended by based on reviews by Thibault Leroy and 1 anonymous reviewer

Identifying the genetic factors that allow plant adaptation is a major scientific question that is particularly relevant in the face of the climate change that we are already experiencing. To address this, it is essential to have genetic information on a high number of accessions (i.e., plants registered with unique accession numbers) growing under contrasting environmental conditions. There is already an important number of studies addressing these issues in the plant Arabidopsis thaliana, but there is a need to expand these analyses to species that play key roles in wild ecosystems and are close to very relevant crops, as is the case of grasses.

The work of Minadakis, Roulin and co-workers (1) presents a Brachypodium distachyon panel of 332 fully sequences accessions that covers the whole species distribution across a wide range of bioclimatic conditions, which will be an invaluable tool to fill this gap. In addition, the authors use this data to start analyzing the population structure and demographic history of this plant, suggesting that the species experienced a shift of its distribution following the Last Glacial Maximum, which may have forced the species into new habitats. The authors also present a modeling of the niches occupied by B. distachyon together with an analysis of the genetic clades found in each of them, and start analyzing the different adaptive loci that may have allowed the species’ expansion into different bioclimatic areas.

In addition to the importance of the resources made available by the authors for the scientific community, the analyses presented are well done and carefully discussed, and they highlight the potential of these new resources to investigate the genetic bases of plant adaptation. 

References

1. Nikolaos Minadakis, Hefin Williams, Robert Horvath, Danka Caković, Christoph Stritt, Michael Thieme, Yann Bourgeois, Anne C. Roulin. The demographic history of the wild crop relative Brachypodium distachyon is shaped by distinct past and present ecological niches. bioRxiv, 2023.06.01.543285, ver. 5 peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2023.06.01.543285

The demographic history of the wild crop relative *Brachypodium distachyon* is shaped by distinct past and present ecological nichesNikolaos Minadakis, Hefin Williams, Robert Horvath, Danka Caković, Christoph Stritt, Michael Thieme, Yann Bourgeois, Anne C. Roulin<p style="text-align: justify;">Closely related to economically important crops, the grass <em>Brachypodium distachyon</em> has been originally established as a pivotal species for grass genomics but more recently flourished as a model for develop...Evolutionary genomics, Functional genomics, Plants, Population genomicsJosep Casacuberta2023-06-14 15:28:30 View
15 Jan 2024
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The genome sequence of the Montseny horsehair worm, Gordionus montsenyensis sp. nov., a key resource to investigate Ecdysozoa evolution

Embarking on a novel journey in Metazoa evolution through the pioneering sequencing of a key underrepresented lineage

Recommended by ORCID_LOGO based on reviews by Gonzalo Riadi and 2 anonymous reviewers

Whole genome sequences are revolutionizing our understanding across various biological fields. They not only shed light on the evolution of genetic material but also uncover the genetic basis of phenotypic diversity. The sequencing of underrepresented lineages, such as the one presented in this study, is of critical importance. It is crucial in filling significant gaps in our understanding of Metazoa evolution. Despite the wealth of genome sequences in public databases, it is crucial to acknowledge that some lineages across the Tree of Life are underrepresented or absent. This research represents a significant step towards addressing this imbalance, contributing to the collective knowledge of the global scientific community.

In this genome note, as part of the European Reference Genome Atlas pilot effort to generate reference genomes for European biodiversity (Mc Cartney et al. 2023), Klara Eleftheriadi and colleagues (Eleftheriadi et al. 2023) make a significant effort to add a genome sequence of an unrepresented group in the animal Tree of Life. More specifically, they present a taxonomic description and chromosome-level genome assembly of a newly described species of horsehair worm (Gordionus montsenyensis). Their sequence methodology gave rise to an assembly of 396 scaffolds totaling 288 Mb, with an N50 value of 64.4 Mb, where 97% of this assembly is grouped into five pseudochromosomes. The nuclear genome annotation predicted 10,320 protein-coding genes, and they also assembled the circular mitochondrial genome into a 15-kilobase sequence.

The selection of a species representing the phylum Nematomorpha, a group of parasitic organisms belonging to the Ecdysozoa lineage, is good, since today, there is only one publicly available genome for this animal phylum (Cunha et al. 2023). Interestingly, this article shows, among other things, that the species analyzed has lost ∼30% of the universal Metazoan genes. Efforts, like the one performed by Eleftheriadi and colleagues, are necessary to gain more insights, for example, on the evolution of this massive gene lost in this group of animals.


References

Cunha, T. J., de Medeiros, B. A. S, Lord, A., Sørensen, M. V., and Giribet, G. (2023). Rampant Loss of Universal Metazoan Genes Revealed by a Chromosome-Level Genome Assembly of the Parasitic Nematomorpha. Current Biology, 33 (16): 3514–21.e4. https://doi.org/10.1016/j.cub.2023.07.003

Eleftheriadi, K., Guiglielmoni, N., Salces-Ortiz, J., Vargas-Chavez, C., Martínez-Redondo, G. I., Gut, M., Flot, J.-F., Schmidt-Rhaesa, A., and Fernández, R. (2023). The Genome Sequence of the Montseny Horsehair worm, Gordionus montsenyensis sp. Nov., a Key Resource to Investigate Ecdysozoa Evolution. bioRxiv, ver. 3 peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2023.06.26.546503

Mc Cartney, A. M., Formenti, G., Mouton, A., De Panis, D., Marins, L. S., Leitão, H. G., Diedericks, G., et al. (2023). The European Reference Genome Atlas: Piloting a Decentralised Approach to Equitable Biodiversity Genomics. bioRxiv. https://doi.org/10.1101/2023.09.25.559365

The genome sequence of the Montseny horsehair worm, *Gordionus montsenyensis* sp. nov., a key resource to investigate Ecdysozoa evolutionEleftheriadi Klara, Guiglielmoni Nadège, Salces-Ortiz Judit, Vargas-Chávez Carlos, Martínez-Redondo Gemma I, Gut Marta, Flot Jean François, Schmidt-Rhaesa Andreas, Fernández Rosa<p>Nematomorpha, also known as Gordiacea or Gordian worms, are a phylum of parasitic organisms that belong to the Ecdysozoa, a clade of invertebrate animals characterized by molting. They are one of the less scientifically studied animal phyla, an...ERGA PilotJuan C. Opazo2023-06-29 10:31:36 View
23 Aug 2022
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A novel lineage of the Capra genus discovered in the Taurus Mountains of Turkey using ancient genomics

Goat ancient DNA analysis unveils a new lineage that may have hybridized with domestic goats

Recommended by based on reviews by Torsten Günther and 1 anonymous reviewer

The genomic analysis of ancient remains has revolutionized the study of the past over the last decade. On top of the discoveries related to human evolution, plant and animal archaeogenomics has been used to gain new insights into the domestication process and the dispersal of domestic forms.

In this study, Daly and colleagues analyse the genomic data from seven goat specimens from the Epipalaeolithic recovered from the Direkli Cave in the Taurus Mountains in southern Turkey. They also generate new genomic data from Capra lineages across the phylogeny, contributing to the availability of genomic resources for this genus. Analysis of the ancient remains is compared to modern genomic variability and sheds light on the complexity of the Tur wild Capra lineages and their relationship with domestic goats and their wild ancestors.

Authors find that during the Late Pleistocene in the Taurus Mountains wild goats from the Tur lineage, today restricted to the Caucasus region, were not rare and cohabited with Bezoar, the wild goats that are the ancestors of domestic goats. They identify the Direkli Cave specimens as a lineage separate from the 
West and East Caucasus Tur modern lineages. Also, analysis of the genomic data and mitochondrial haplotypes reveals hybridization between the Tur and the Bezoar wild lineages. Interestingly, authors also find an uneven amount of Tur ancestry among Neolithic domestic goats, with European domestic goats showing evidence of this ancient Tur ancestry, whereas Neolithic Iranian domestic goats do not, a pattern that is also observed in some modern European domestic goats.

A modified D statistic, Dex, is developed to examine the contribution of the ancient Tur lineage in domestic goats through time and space. Dex measures the relative degree of allele sharing, derived specifically in a selected genome or group of genomes, and may have some utility in genera with complex admixture histories or admixture from ghost lineages. Results confirm that Neolithic European goat had an excess of allele sharing with this ancient Tur lineage, something that is absent in contemporary goats eastwards or in modern goats.

Interspecific gene flow is not uncommon among mammals, but the case of Capra has the additional motivation of understanding the origins of the domestic species. This work uncovers an ancient Tur lineage that is different from the modern ones and is additionally found in another geographic area. Furthermore, evidence shows that this ancient lineage exhibits substantial amounts of allele sharing with the wild ancestor of the domestic goat, but also with the Neolithic Eurasian domestic goats, highlighting the complexity of the domestication process.

This work has also important implications in understanding the effect of over-hunting and habitat disruption during the Anthropocene on the evolution of the Capra genus. The availability of more ancient specimens and better coverage of the modern genomic variability can help quantifying the lineages that went lost and identify the causes of their extinction.

This work is limited by the current availability of whole genomes from modern Capra specimens, but pieces of evidence as well that an effort is needed to obtain more genomic data from ancient goats from different geographic ranges to determine to what extent these lineages contributed to goat domestication.

References

Daly KG, Arbuckle BS, Rossi C, Mattiangeli V, Lawlor PA, Mashkour M, Sauer E, Lesur J, Atici L, Cevdet CM and Bradley DG (2022) A novel lineage of the Capra genus discovered in the Taurus Mountains of Turkey using ancient genomics. bioRxiv, 2022.04.08.487619, ver. 5 peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2022.04.08.487619

A novel lineage of the Capra genus discovered in the Taurus Mountains of Turkey using ancient genomicsKevin G. Daly, Benjamin S. Arbuckle, Conor Rossi, Valeria Mattiangeli, Phoebe A. Lawlor, Marjan Mashkour, Eberhard Sauer, Joséphine Lesur, Levent Atici, Cevdet Merih Erek, Daniel G. Bradley<p>Direkli Cave, located in the Taurus Mountains of southern Turkey, was occupied by Late Epipaleolithic hunters-gatherers for the seasonal hunting and processing of game including large numbers of wild goats. We report genomic data from new and p...Evolutionary genomics, Population genomics, VertebratesLaura Botigué2022-04-15 12:05:47 View
12 Jul 2022
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Chromosome-level genome assembly and annotation of two lineages of the ant Cataglyphis hispanica: steppingstones towards genomic studies of hybridogenesis and thermal adaptation in desert ants

A genomic resource for ants, and more

Recommended by based on reviews by Isabel Almudi and Nicolas Nègre

The ant species Cataglyphis hispanica is remarkably well adapted to arid habitats of the Iberian Peninsula where two hybridogenetic lineages co-occur, i.e., queens mating with males from the other lineage produce only non-reproductive hybrid workers whereas reproductive males and females are produced by parthenogenesis (Lavanchy and Schwander, 2019). For these two reasons, the genomes of these lineages, Chis1 and Chis2, are potential gold mines to explore the genetic bases of thermal adaptation and the evolution of alternative reproductive modes.

Nowadays, sequencing technology enables assembling all kinds of genomes provided genomic DNA can be extracted. More difficult to achieve is high-quality assemblies with just as high-quality annotations that are readily available to the community to be used and re-used at will (Byrne et al., 2019; Salzberg, 2019). The challenge was successfully completed by Darras and colleagues, the generated resource being fully available to the community, including scripts and command lines used to obtain the proposed results.

The authors particularly describe that lineage Chis2 has 27 chromosomes, against 26 or 27 for lineage Chis1, with a Robertsonian translocation identified by chromosome conformation capture (Duan et al., 2010, 2012) in the two Queens sequenced. Transcript-supported gene annotation provided 11,290 high-quality gene models. In addition, an ant-tailored annotation pipeline identified 56 different families of repetitive elements in both Chis1 and Chis2 lineages of C. hispanica spread in a little over 15 % of the genome. Altogether, the genomes of Chis1 and Chis2 are highly similar and syntenic, with some level of polymorphism raising questions about their evolutionary story timeline. In particular, the uniform distribution of polymorphisms along the genomes shakes up a previous hypothesis of hybridogenetic lineage pairs determined by ancient non-recombining regions (Linksvayer, Busch and Smith, 2013).

I recommend this paper because the science behind is both solid and well-explained. The provided resource is of high quality, and accompanied by a critical exploration of the perspectives brought by the results. These genomes are excellent resources to now go further in exploring the possible events at the genome level that accompanied the remarkable thermal adaptation of the ants Cataglyphis, as well as insights into the genetics of hybridogenetic lineages.

Beyond the scientific value of the resources and insights provided by the work performed, I also recommend this article because it is an excellent example of Open Science (Allen and Mehler, 2019; Sarabipour et al., 2019), all data methods and tools being fully and easily accessible to whoever wants/needs it. 

References

Allen C, Mehler DMA (2019) Open science challenges, benefits and tips in early career and beyond. PLOS Biology, 17, e3000246. https://doi.org/10.1371/journal.pbio.3000246

Byrne A, Cole C, Volden R, Vollmers C (2019) Realizing the potential of full-length transcriptome sequencing. Philosophical Transactions of the Royal Society B: Biological Sciences, 374, 20190097. https://doi.org/10.1098/rstb.2019.0097

Darras H, de Souza Araujo N, Baudry L, Guiglielmoni N, Lorite P, Marbouty M, Rodriguez F, Arkhipova I, Koszul R, Flot J-F, Aron S (2022) Chromosome-level genome assembly and annotation of two lineages of the ant Cataglyphis hispanica: stepping stones towards genomic studies of hybridogenesis and thermal adaptation in desert ants. bioRxiv, 2022.01.07.475286, ver. 3 peer-reviewed and recommended by Peer community in Genomics. https://doi.org/10.1101/2022.01.07.475286

Duan Z, Andronescu M, Schutz K, Lee C, Shendure J, Fields S, Noble WS, Anthony Blau C (2012) A genome-wide 3C-method for characterizing the three-dimensional architectures of genomes. Methods, 58, 277–288. https://doi.org/10.1016/j.ymeth.2012.06.018

Duan Z, Andronescu M, Schutz K, McIlwain S, Kim YJ, Lee C, Shendure J, Fields S, Blau CA, Noble WS (2010) A three-dimensional model of the yeast genome. Nature, 465, 363–367. https://doi.org/10.1038/nature08973

Lavanchy G, Schwander T (2019) Hybridogenesis. Current Biology, 29, R9–R11. https://doi.org/10.1016/j.cub.2018.11.046

Linksvayer TA, Busch JW, Smith CR (2013) Social supergenes of superorganisms: Do supergenes play important roles in social evolution? BioEssays, 35, 683–689. https://doi.org/10.1002/bies.201300038

Salzberg SL (2019) Next-generation genome annotation: we still struggle to get it right. Genome Biology, 20, 92. https://doi.org/10.1186/s13059-019-1715-2

Sarabipour S, Debat HJ, Emmott E, Burgess SJ, Schwessinger B, Hensel Z (2019) On the value of preprints: An early career researcher perspective. PLOS Biology, 17, e3000151. https://doi.org/10.1371/journal.pbio.3000151

Chromosome-level genome assembly and annotation of two lineages of the ant Cataglyphis hispanica: steppingstones towards genomic studies of hybridogenesis and thermal adaptation in desert antsHugo Darras, Natalia de Souza Araujo, Lyam Baudry, Nadège Guiglielmoni, Pedro Lorite, Martial Marbouty, Fernando Rodriguez, Irina Arkhipova, Romain Koszul, Jean-François Flot, Serge Aron<p style="text-align: justify;"><em>Cataglyphis</em> are thermophilic ants that forage during the day when temperatures are highest and sometimes close to their critical thermal limit. Several Cataglyphis species have evolved unusual reproductive ...Evolutionary genomicsNadia Ponts Nicolas Nègre, Isabel Almudi2022-01-13 16:47:30 View
08 Nov 2022
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Somatic mutation detection: a critical evaluation through simulations and reanalyses in oaks

How to best call the somatic mosaic tree?

Recommended by based on reviews by 2 anonymous reviewers

Any multicellular organism is a molecular mosaic with some somatic mutations accumulated between cell lineages. Big long-lived trees have nourished this imaginary of a somatic mosaic tree, from the observation of spectacular phenotypic mosaics and also because somatic mutations are expected to potentially be passed on to gametes in plants (review in Schoen and Schultz 2019). The lower cost of genome sequencing now offers the opportunity to tackle the issue and identify somatic mutations in trees.

However, when it comes to characterizing this somatic mosaic from genome sequences, things become much more difficult than one would think in the first place. What separates cell lineages ontogenetically, in cell division number, or in time? How to sample clonal cell populations? How do somatic mutations distribute in a population of cells in an organ or an organ sample? Should they be fixed heterozygotes in the sample of cells sequenced or be polymorphic? Do we indeed expect somatic mutations to be fixed? How should we identify and count somatic mutations?

To date, the detection of somatic mutations has mostly been done with a single variant caller in a given study, and we have little perspective on how different callers provide similar or different results. Some studies have used standard SNP callers that assumed a somatic mutation is fixed at the heterozygous state in the sample of cells, with an expected allele coverage ratio of 0.5, and less have used cancer callers, designed to detect mutations in a fraction of the cells in the sample. However, standard SNP callers detect mutations that deviate from a balanced allelic coverage, and different cancer callers can have different characteristics that should affect their outcomes.

In order to tackle these issues, Schmitt et al. (2022) conducted an extensive simulation analysis to compare different variant callers. Then, they reanalyzed two large published datasets on pedunculate oak, Quercus robur.  The analysis of in silico somatic mutations allowed the authors to evaluate the performance of different variant callers as a function of the allelic fraction of somatic mutations and the sequencing depth. They found one of the seven callers to provide better and more robust calls for a broad set of allelic fractions and sequencing depths. The reanalysis of published datasets in oaks with the most effective cancer caller of the in silico analysis allowed them to identify numerous low-frequency mutations that were missed in the original studies.

I recommend the study of Schmitt et al. (2022) first because it shows the benefit of using cancer callers in the study of somatic mutations, whatever the allelic fraction you are interested in at the end. You can select fixed heterozygotes if this is your ultimate target, but cancer callers allow you to have in addition a valuable overview of the allelic fractions of somatic mutations in your sample, and most do as well as SNP callers for fixed heterozygous mutations. In addition, Schmitt et al. (2022) provide the pipelines that allow investigating in silico data that should correspond to a given study design, encouraging to compare different variant callers rather than arbitrarily going with only one. We can anticipate that the study of somatic mutations in non-model species will increasingly attract attention now that multiple tissues of the same individual can be sequenced at low cost, and the study of Schmitt et al. (2022) paves the way for questioning and choosing the best variant caller for the question one wants to address.

References

Schoen DJ, Schultz ST (2019) Somatic Mutation and Evolution in Plants. Annual Review of Ecology, Evolution, and Systematics, 50, 49–73. https://doi.org/10.1146/annurev-ecolsys-110218-024955

Schmitt S, Leroy T, Heuertz M, Tysklind N (2022) Somatic mutation detection: a critical evaluation through simulations and reanalyses in oaks. bioRxiv, 2021.10.11.462798. ver. 4 peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2021.10.11.462798

Somatic mutation detection: a critical evaluation through simulations and reanalyses in oaksSylvain Schmitt, Thibault Leroy, Myriam Heuertz, Niklas Tysklind<p style="text-align: justify;">1. Mutation, the source of genetic diversity, is the raw material of evolution; however, the mutation process remains understudied, especially in plants. Using both a simulation and reanalysis framework, we set out ...Bioinformatics, PlantsNicolas BierneAnonymous, Anonymous2022-04-28 13:24:19 View
09 Aug 2023
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Efficient k-mer based curation of raw sequence data: application in Drosophila suzukii

Decontaminating reads, not contigs

Recommended by based on reviews by Marie Cariou and Denis Baurain

Contamination, the presence of foreign DNA sequences in a sample of interest, is currently a major problem in genomics. Because contamination is often unavoidable at the experimental stage, it is increasingly recognized that the processing of high-throughput sequencing data must include a decontamination step. This is usually performed after the many sequence reads have been assembled into a relatively small number of contigs. Dubious contigs are then discarded based on their composition (e.g. GC-content) or because they are highly similar to a known piece of DNA from a foreign species.

Here [1], Mathieu Gautier explores a novel strategy consisting in decontaminating reads, not contigs. Why is this promising? Assembly programs and algorithms are complex, and it is not easy to predict, or monitor, how they handle contaminant reads. Ideally, contaminant reads will be assembled into obvious contaminant contigs. However, there might be more complex situations, such as chimeric contigs with alternating genuine and contaminant segments. Decontaminating at the read level, if possible, should eliminate such unfavorable situations where sequence information from contaminant and target samples are intimately intertwined by an assembler.

To achieve this aim, Gautier proposes to use methods initially designed for the analysis of metagenomic data. This is pertinent since the decontamination process involves considering a sample as a mixture of different sources of DNA. The programs used here, CLARK and CLARK-L, are based on so-called k-mer analysis, meaning that the similarity between a read to annotate and a reference sequence is measured by how many sub-sequences (of length 31 base pairs for CLARK and 27 base pairs for CLARK-L) they share. This is notoriously more efficient than traditional sequence alignment algorithms when it comes to comparing a very large number of (most often unrelated) sequences. This is, therefore, a reference-based approach, in which the reads from a sample are assigned to previously sequenced genomes based on k-mer content.

This original approach is here specifically applied to the case of Drosophila suzukii, an invasive pest damaging fruit production in Europe and America. Fortunately, Drosophila is a genus of insects with abundant genomic resources, including high-quality reference genomes in dozens of species. Having calibrated and validated his pipeline using data sets of known origins, Gautier quantifies in each of 258 presumed D. suzukii samples the proportion of reads that likely belong to other species of fruit flies, or to fruit fly-associated microbes. This proportion is close to one in 16 samples, which clearly correspond to mis-labelled individuals. It is non-negligible in another ~10 samples, which really correspond to D. suzukii individuals. Most of these reads of unexpected origin are contaminants and should be filtered out. Interestingly, one D. suzukii sample contains a substantial proportion of reads from the closely related D. subpulchera, which might instead reflect a recent episode of gene flow between these two species. The approach, therefore, not only serves as a crucial technical step, but also has the potential to reveal biological processes.

Gautier's thorough, well-documented work will clearly benefit the ongoing and future research on D. suzuki, and Drosophila genomics in general. The author and reviewers rightfully note that, like any reference-based approach, this method is heavily dependent on the availability and quality of reference genomes - Drosophila being a favorable case. Building the reference database is a key step, and the interpretation of the output can only be made in the light of its content and gaps, as illustrated by Gautier's careful and detailed discussion of his numerous results. 

This pioneering study is a striking demonstration of the potential of metagenomic methods for the decontamination of high-throughput sequence data at the read level. The pipeline requires remarkably few computing resources, ensuring low carbon emission. I am looking forward to seeing it applied to a wide range of taxa and samples.

 

Reference

[1] Gautier Mathieu. Efficient k-mer based curation of raw sequence data: application in Drosophila suzukii. bioRxiv, 2023.04.18.537389​, ver. 2, peer-reviewed and recommended by Peer Community in Genomics. https://doi.org/10.1101/2023.04.18.537389​

Efficient k-mer based curation of raw sequence data: application in *Drosophila suzukii*Gautier Mathieu<p>Several studies have highlighted the presence of contaminated entries in public sequence repositories, calling for special attention to the associated metadata. Here, we propose and evaluate a fast and efficient kmer-based approach to assess th...Bioinformatics, Population genomicsNicolas Galtier2023-04-20 22:05:13 View