Biology subjects

Pozo, G.

Publications and source records attributed to Pozo, G..

9 recordsLinked to original sources

bioRxiv2026

A Highly Contiguous Reference Genome for Scalesia gordilloi (Asteraceae), a Critically Endangered Plant Endemic to the Galapagos Islands

Scalesia gordilloi is a critically endangered species endemic to San Cristobal Island in the Galapagos archipelago and represents one of the most unique and vulnerable lineages within the adaptive radiation of the genus Scalesia. Despite its evolutionary distinctiveness and conservation importance, no genomic resources have been available for this species. Here, we present the first high-quality reference genome of S. gordilloi, generated using Oxford Nanopore long-read sequencing. Across three PromethION R10.4.1 flow cells, we obtained 80.5 Gb of long reads ([~]25x coverage), which enabled a highly contiguous 3.61 Gb assembly composed of only 549 contigs and an N50 of 106.6 Mb. BUSCO completeness reached 98.6%, with assembly metrics comparable to other high-quality Asteraceae genomes. Repeat annotation revealed that 76.2% of the genome is composed of interspersed elements, dominated by LTR retrotransposons. Structural annotation resulted in 47,913 high-confidence protein-coding genes, consistent with expectations for large, repetitive Asteraceae genomes. This genome provides a critical foundation for conservation genomics, enabling assessments of genetic diversity, inbreeding, and adaptive potential in the species. It further establishes a framework for comparative genomics across the Scalesia radiation and supports future efforts to protect and restore one of the most threatened plant lineages of the Galapagos Islands.

genomics↗

bioRxiv2026

Highly contiguous reference genome assembly of the endangered Orces blue whiptail Holcosus orcesi

Holcosus orcesi, the Orces Blue Whiptail, is a Critically Endangered lizard endemic to the upper Jubones River basin in southern Ecuador. Restricted to a narrow elevational range within semi-arid Andean shrublands, it represents one of the few montane members of a predominantly lowland lineage. Here we present the first high-quality reference genome for H. orcesi, generated using Oxford Nanopore Technologies long-read sequencing. The assembly spans 1.68 Gb across only 91 contigs, with an N50 of 76.2 Mb and a BUSCO completeness of 96.8%, making it among the most contiguous and complete squamate genomes to date. Structural annotation predicted 25,682 genes, of which 85% showed homology to known proteins and 45% were assigned Gene Ontology terms. Repetitive elements accounted for 46.3% of the genome, with LINEs representing the predominant class. This genome provides a foundational resource for future evolutionary, comparative and conservation-genomic research of H. orcesi and other mountain reptiles, enabling studies of population genomics, local adaptation, and genomic erosion in isolated populations. By expanding the genomic representation of tropical montane reptiles, this work helps address longstanding phylogenetic and geographic gaps in global biodiversity genomics and provides a foundation for evidence-based conservation of H. orcesi and related taxa.

genomics↗

bioRxiv2025

The histone variant H2A.Z and its chaperone SRCAP are required for RNA polymerase II to access HBV chromatin

BackgroundChronic hepatitis B virus (HBV) infection remains a major global health burden due to the persistence of covalently closed circular DNA (cccDNA), a stable episomal viral reservoir resistant to current antiviral therapies. The transcriptional activity of cccDNA depends on its chromatin organization, yet the contribution of histone variants to this regulation remains poorly understood. MethodsUsing mass spectrometry-based proteomics on native cccDNA purified from infected primary human hepatocytes, we identified the histone variant H2A.Z and its chaperone SRCAP as cccDNA-associated proteins. Functional analyses combining shRNA-mediated silencing, chromatin immunoprecipitation (ChIP), and ATAC-seq were performed in HBV-infected HepG2-NTCP cells and primary human hepatocytes to characterize their roles in cccDNA formation and transcription. ResultsDepletion of H2A.Z.1, H2A.Z.2, or SRCAP reduced both HBV RNA levels and cccDNA formation. H2A.Z recruitment to cccDNA correlated with the establishment of active chromatin marks (H3K4me3) and enhanced RNA polymerase II loading, promoting an open and transcriptionally active chromatin state. In addition, we identified BRD2, an H2A.Z-associated transcriptional co-activator, as a positive regulator of HBV transcription. shRNA mediated depletion and pharmacological degradation of BRD2 using the PROTAC ARV-771 reduced HBV RNA levels, supporting its potential as an antiviral target. ConclusionOur findings uncover a critical role of the H2A.Z variant and SRCAP complex in cccDNA formation and transcriptional activation. By facilitating chromatin accessibility and RNA polymerase II recruitment, H2A.Z establishes an epigenetic environment favorable to HBV persistence. Targeting H2A.Z-associated co-activators such as BRD2 may represent a promising strategy to silence cccDNA transcription and achieve functional HBV cure.

microbiology↗

bioRxiv2025

High-Quality De Novo Genome Assembly for the Galapagos Endemic Lava Gull Using Oxford Nanopore Technologies

High-quality reference genomes permit deeper investigation into species evolution and provide insight into species management and conservation. Next-generation sequencing technologies, such as Oxford Nanopore Technologies, allow researchers to generate high-accuracy long-read genetic data in real-time from anywhere in the world, increasing accessibility to sequence data. The lava gull (Leucophaeus fuliginosus), an endemic bird species of the Galapagos archipelago, is the worlds rarest gull with an estimated population of 300 to 600 individuals. Little genetic research has been done on this species due to its solitary nature and small population size. Here we present a chromosome-level reference genome assembly of an adult female lava gull, generated using ultra-long reads from the Oxford Nanopore Ultra-Long DNA Sequencing Kit and a PromethION 2 Solo device. Initial sequencing generated 1.78 million reads, consisting of 29.6 gigabases (Gbp), with a mean Q-score of 17.8 at an average 22.5x coverage. Our final assembly has a total length of 1.31 Gbp, with 450 scaffolds, and a scaffold N50 of 85.1 Mbp and contig N50 of 42.8 Mbp. The generation of a high-quality whole genome for the lava gull is an important step for investigation into the species phylogeography and population genetics.

genomics↗

bioRxiv2025

First Whole-Genome Assembly of the Galapagos Petrel (Pterodroma phaeopygia) Using Oxford Nanopore Sequencing to Advance Conservation Genomics in a Critically Endangered Seabird

The Galapagos petrel (Pterodroma phaeopygia) is a critically endangered procellariiform seabird endemic to the Galapagos Islands. Once abundant, its populations have sharply declined due to invasive predators, habitat degradation, and destruction of nest burrows. Although the species is distributed across several islands, the demographics of each population and their genetic relationships are poorly understood. To facilitate future studies of population structure and connectivity, we present the first high-quality reference genome for the Galapagos petrel. The genome was assembled from ultra-long Oxford Nanopore sequence data collected from an adult female sampled on San Cristobal Island. Sequencing was performed at the Galapagos Science Center, enabling local capacity-building and compliance with strict sample import-export regulations of endangered species. The final nuclear genome assembly spans 1.35 Gb in length, with average coverage of 36.07x, scaffold N50 of 74.2 Mb, and a BUSCO aves lineage completeness of 99.95%. The genome comprises 41 pseudo-chromosomes, with 23 spanning from telomere to telomere and 16, including W and Z chromosomes, containing a single telomere. Chromosomal-level scaffolding by reference was performed using the genome of Corys shearwater (Calonectris borealis) GCA_964196065.2 (Aranega et al., 2024), a related species. The Galapagos petrel reference genome represents a foundational tool for comparative genomics, conservation biology, and functional studies of island-endemic avifauna. It will also facilitate future efforts to characterize genetic diversity, structural variation, and adaptive responses in this critically endangered species.

genomics↗

bioRxiv2024

First whole genome assembly of Vaccinium floribundum Kunth, an emblematic Andean species

BackgroundVaccinium floribundum Kunth, known as "mortino," is an endemic shrub species of the Andean region adapted to harsh conditions in high-altitude ecosystems. It plays an important ecological role as a pioneer species in the aftermath of deforestation and human-induced fires within paramo ecosystems, emphasizing its conservation value. While previous studies have offered insights into the genetic diversity of mortino, comprehensive genomic studies are still missing to fully understand the unique adaptations of this species and its population status, highlighting the importance of generating a reference genome for this plant. ResultsONT and Illumina sequencing were used to establish a reference genome for this species. Three different de novo genome assemblies were generated and compared for quality, continuity and completeness. The Flye assembly was selected as the best and refined by filtering out short ONT reads, screening for contaminants and genome scaffolding. The final assembly has a genome size of 529 MB, containing 1,317 contigs and 97% complete BUSCOs, indicating a high level of integrity of the genome. Additionally, the LAI Index of 12.93, further categorizes this assembly as a reference genome. ConclusionsThe genome of V. floribundum reported in this study is the first reference genome generated for this species, providing a valuable tool for further studies. This high-quality genome, based on the quality and completeness parameters obtained, will not only help uncover the genetic mechanisms responsible for its unique traits and adaptations to high-altitude ecosystems, but will also contribute to conservation strategies for a species endemic to the Andes.

genomics↗

bioRxiv2023

First whole genome sequence and assembly of the Ecuadorian brown-headed spider monkey (Ateles fusciceps fusciceps), a critically endangered species, using Oxford Nanopore Technologies

The Ecuadorian brown-headed spider monkey (Ateles fusciceps fusciceps) is currently considered one of the most endangered primates in the world and is classified as critically endangered (IUCN). It faces multiple threats, the most significant one being habitat loss due to deforestation in western Ecuador. Genomic tools are key for the management of endangered species, but this requires a reference genome which until now was unavailable for A. f. fusciceps. The present study reports the first whole genome sequence and assembly of A. f. fusciceps generated using Oxford Nanopore long reads. DNA was extracted from a subadult male and libraries were prepared for sequencing following the Ligation Sequencing Kit SQK-LSK112 workflow. Sequencing was performed using a MinION Mk1C sequencer. The sequencing reads were processed to generate a genome assembly. Two different assemblers were used to obtain draft genomes using raw reads, of which the Flye assembly was found to be superior. The final assembly has a total length of 2.63 Gb and contains 3,861 contigs, with an N50 of 7,560,531 bp. The assembly was analyzed for annotation completeness based on primate ortholog prediction using a high-resolution database, and was found to be 84.3% complete, with a low number of duplicated genes indicating a precise assembly. The annotation of the assembly predicted 31,417 protein-coding genes, comparable to other mammal assemblies. A reference genome for this critically endangered species will allow researchers to gain insight into the genetics of its populations and thus aid conservation and management efforts of this vulnerable species.

genomics↗

bioRxiv2020

Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

Oceanic archipelagos are known to host a variety of endemic plant species. The genetic diversity and structure of these species is an important indicator of their evolutionary history and can inform appropriate conservation strategies that mitigate the risks to which theyre exposed, including invasive species and environmental disturbances. A comprehensive consideration of the role of their natural history, as well as the landscape features and the geological history of the islands themselves is required to adequately understand any emerging patterns. Such is the case for the guayabillo (Psidium galapageium), an understudied endemic plant from the Galapagos Islands with important ecological and economic roles. In this study we designed and evaluated 13 informative SSR markers and used them to investigate the genetic diversity, population structure and connectivity of the guayabillo populations from San Cristobal, Isabela and Santa Cruz islands. A total of 208 guayabillo individuals were analyzed, revealing a strong population structure between islands and two distinct genetic lineages for the Santa Cruz population. Overall, the guayabillo genetic diversity is relatively high, an unusual pattern for an insular endemic species which is possibly explained by its polyploidy and the geographical features of the islands. These include their broad altitudinal ranges and habitat heterogeneity. For populations displaying a lower genetic diversity such as San Cristobal, the history of human disturbance could be an important factor explaining these observations. Some similarities between individuals in Santa Cruz and the San Cristobal population could be explained by population differentiation or distinct natural histories of separate lineages. Our findings highlight the complex population dynamics that shape the genetic diversity of species like the guayabillo and emphasize the need to explore the currently unresolved questions about this Galapagos endemic plant.

plant biology↗

bioRxiv2018

Psidium guajava in the Galapagos Islands: population genetics and history of an invasive species

The threat of invasive plant species in island populations prompts the need to better understand their population genetics and dynamics. In the Galapagos islands, this is exemplified by the introduced guava (Psidium guajava), considered one of the greatest threats to the local biodiversity due to its effective spread in the archipelago and its ability to outcompete endemic species. To better understand its history and genetics, we analyzed individuals from three inhabited islands in the Galapagos archipelago with 11 SSR markers. Our results reveal similar genetic diversity between islands, suggestive of gene flow between them. Populations appear to be distinct between the islands of San Cristobal and Isabela, with the population of Santa Cruz being composed as a mixture from both. Additional evidence for genetic bottlenecks and the inference of introduction events suggests an original introduction of the species in San Cristobal, from where it was later introduced to Isabela, and finally into Santa Cruz. Alternatively, an independent introduction event for Isabela is also possible. These results are contrasted with the historical record, providing a first overview of the history of P. guajava in the Galapagos islands and its current population dynamics.

evolutionary biology↗