Latest Articles

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  Section: Genomics ; Topics: Genetics/genomics, Environmental sciences

  Two de novo transcriptome assemblies and functional annotations from juvenile cuttlefish (Sepia officinalis) under various metal and pCO₂ exposure conditions

  Thomas, Sol Dourdin;   Antoine, Minet;   Eric, Pante;   Thomas, Lacoue-Labarthe  

  10.24072/pcjournal.703 - Peer Community Journal, Volume 6 (2026), article no. e28

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  The cuttlefish Sepia officinalis is a precious model in behavioural and neurobiology studies. It is currently facing combined environmental changes related to the anthropogenic global change. However, genomic resources available to support investigations tackling this issue are still scarce. Therefore, we present two annotated de novo transcriptome assemblies from recently hatched (whole body) and one-month old (head) Sepia officinalis juveniles. Both assemblies rely on an important read depth validated by a pseudo-rarefaction analysis, and gathered several individuals from various metal and pCO₂ exposure conditions. After redundancy reduction, assemblies from newly hatched and one-month-old individuals comprised 230,672 and 370,613 transcripts with 35,590 and 44,233 putative ORFs, respectively, and an annotation rate arounf 70%. Assemblies were compared to each other, revealing age-specific transcriptomic landscapes. These two assemblies constitute highly valuable genomic resources complementing reference genome assembly and facilitating the investigation of transcriptomic endpoints in environmental studies considering coleoid cephalopods.

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  Section: Genomics ; Topics: Genetics/genomics ; Conference: JOBIM

  Benchmarking circRNA Detection Tools from Long-Read Sequencing Using Data-Driven and Flexible Simulation Framework

  Rusakovich, Anastasia;   Corre, Sebastien;   Cadieu, Edouard; Fraboulet, Rose-Marie; Le Bars, Victor;   Galibert, Marie-Dominique;   Derrien, Thomas;   Blum, Yuna  

  10.24072/pcjournal.699 - Peer Community Journal, Volume 6 (2026), article no. e27

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  Circular RNAs (circRNAs) are unique non-coding RNAs with covalently closed loop structures formed through backsplicing events. Their stability, tissue-specific expression patterns, and potential as disease biomarkers have garnered increasing attention. However, their circular structure and diverse size range pose challenges for conventional sequencing technologies. Long-read Oxford Nanopore (ONT) sequencing offers promising capabilities for capturing entire circRNA molecules without fragmentation, yet the effectiveness of bioinformatic tools for analyzing this data remains understudied. This study presents the first comprehensive benchmark comparison of three specialized tools for circRNA detection from ONT long-read data: CIRI-long (Zhang et al., 2021), IsoCIRC (Xin et al., 2021), and circNICK-Irs (Rahimi et al., 2021). To address the lack of standardized evaluation frameworks, we developed a novel computational pipeline, open-source and freely available, to generate realistic simulated circRNA ONT long-read datasets. Our pipeline integrates several molecular features of circRNAs extracted from established databases and real datasets into NanoSim tool (Hafezqorani et al., 2020) and outputs FASTQ reads reflecting therefore biological diversity and technical properties. We systematically assessed tool performance across key metrics, including precision, recall and F1 score. Our analysis revealed distinct performance profiles: while all tools exhibited high specificity, they varied in precision and their ability to detect different circRNA subtypes, often showing limited sensitivity and precision. Notably, the overlap in detected circRNAs among tools was relatively low. Additionally, computational efficiency varied significantly across the tools. This suggests that relying on a single tool might not be ideal, and combining tools or improving algorithms could be necessary for more accurate circRNA detection from ONT data. This benchmark provides valuable insights for researchers selecting appropriate tools for circRNA studies using ONT sequencing. Furthermore, our customizable simulation framework, offering a resource to optimize detection approaches and advance bioinformatic tool development for circRNA research is freely available at: https://gitlab.com/bingo-igdr/nano-circ

   

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  Section: Evolutionary Biology ; Topics: Evolution, Genetics/genomics

  Limited directional selection but coevolutionary signals among imprinted genes in A. lyrata

  Le veve, Audrey;   Iltas, Ömer;   Dutheil, Julien;   Lafon Placette, Clement  

  10.24072/pcjournal.702 - Peer Community Journal, Volume 6 (2026), article no. e26

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  Genomic imprinting is a form of gene regulation leading to the unequal expression of maternal and paternal alleles. The main hypothesis invoked to explain the evolution of imprinted genes is the kinship theory, which posits a conflict between parental genomes over resource allocation in progeny. According to this theory, such conflicts select for parent-of-origin–dependent expression of genes involved in resource allocation. How such conflicts translate into signatures of selection at coding or regulatory sequences remains model-dependent and is not explicitly predicted by the kinship theory. However, most studies addressing selection in imprinted genes in flowering plants, particularly those based on population-genomic or phylogenetic analyses, have focused on self-fertilizing species, where conflicts over resource allocation are predicted to be weak. Consequently, the impact of the kinship theory on the evolution of imprinted genes remains largely unexplored in systems where parental conflict is expected to be strong. Furthermore, potential coevolution between antagonistically acting imprinted genes, as proposed in extensions of parental conflict models, has not yet been tested empirically. Using combined phylogenetic and population genomic approaches, we investigated signatures of selection on imprinted genes across the Brassicaceae family and in autogamous and allogamous populations of Arabidopsis lyrata, and searched for evidence of coevolution among imprinted genes. We found that endosperm-expressed genes exhibited signals of balancing selection across Brassicaceae and within allogamous populations, consistent with models of unresolved intralocus conflict. These population-level signals varied with the mating system, in line with expectations that parental conflict is reduced under self-fertilization. Moreover, phylogenetic analyses indicated signatures of purifying (negative) selection acting on imprinted genes. However, the population-level signatures of selection were independent of the mating system and showed limited concordance with kinship predictions, possibly due to stronger selection acting on expression than on coding sequences. Finally, we identified coevolution between imprinted genes, although not at specific sites, suggesting that interactions beyond protein sequence may contribute to this process.

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  Section: Evolutionary Biology ; Topics: Evolution

  The effect of gene tree dependence on summary methods for species tree inference

  He, Wanting;   Scornavacca, Celine;   Chan, Yao-ban  

  10.24072/pcjournal.694 - Peer Community Journal, Volume 6 (2026), article no. e25

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  When inferring the evolutionary history of species and the genes they contain, the phylogenetic trees of genes can be different from those of the species and to each other, due to a variety of causes, including incomplete lineage sorting. We often wish to infer the species tree, but only reconstruct the gene trees from sequences. We then combine the gene trees to produce a species tree; methods to do this are known as summary methods, of which ASTRAL is currently among the most popular. ASTRAL has been shown to be accurate in many practical scenarios through extensive simulations. However, these simulations generally assume that the input gene trees are independent of each other (infinite recombination between loci). This is known to be unrealistic, as genes that are close to each other on the chromosome (or are co-evolving) have dependent phylogenies. In this paper, we develop a model for generating dependent gene trees within a species tree, based on the coalescent with recombination. We then use these trees as input to ASTRAL to reassess its accuracy for dependent gene trees. Our results allow us to evaluate the impact of any level of dependence on the accuracy of ASTRAL, both when gene trees are known and estimated from sequences. We find that a fixed amount of dependence reduces the effective sample size by a constant factor. In current phylogenomic datasets, loci are generally sampled at large genomic distances to reduce gene tree dependence, thereby limiting the number of genes available for inference. However, full independence between genes is not required for accurate species tree estimation, and excluding gene trees may reduce inference accuracy. This creates a trade-off between the number of genes used and the degree of gene tree dependence. We therefore propose a method to identify the minimum genomic separation required to maintain satisfactory inference accuracy.