Biology subjects

Albertini, M.

Publications and source records attributed to Albertini, M..

4 recordsLinked to original sources

bioRxiv2026

Integrated genomics and transcriptomics reveal mechanisms of extreme dietary adaptation in vampire bats

Vampire bats are the only tetrapods that feed exclusively on blood. To uncover the molecular basis of this extreme dietary specialization, we generated six new reference genomes, including genomes of all three vampire bat species, and integrated comparative analyses of gene sequence evolution (selection signatures, duplications, and losses) with transcriptomic data from six major organs to identify shifts in gene expression. Our integrative analyses reveal sequence or expression changes in 150 genes that illuminate the genetic mechanisms underlying sanguivory. Through comparative analyses and experiments, we show that the enlarged vampire bat stomach has increased connective tissue content enabling extreme expansion, is pH-neutral, and exhibits reduced mucus production, together providing molecular insights into its shift from a digestive to an absorptive organ for water, electrolytes, and vitamins. We further uncover pathway-level molecular changes underlying altered gastrointestinal motility; trypsin-dependent protein digestion; upregulated amino acid catabolism with key aspects diverging from other mammals; impaired dietary fat digestion counterbalanced by increased fatty acid synthesis; defective sugar metabolism and natural insulin deficiency; enhanced heme iron absorption; and adult splenic erythropoiesis. Together, these findings reveal the molecular adaptations that enable one of the most extreme dietary transitions among vertebrates.

evolutionary biology↗

bioRxiv2026

CRISPR-Cas interference decays rapidly with distance from the leader sequence in a long array

Spacer efficacy generally declines with distance from the leader sequence, but the scarcity of fine-scale studies hampers comparisons across taxa. Here, we investigated positional effects across an exceptionally long 121-spacer CRISPR array associated with the type I-C cas operon of a Myxococcus xanthus natural isolate. In plasmid-interference assays, we found that interference rapidly declined with distance from the leader sequence, with only the proximal [~]4% of spacers conferring measurable interference. This contrasts strikingly with a study in Vibrio cholerae, in which it was shown that [~]95% of spacers in a shorter (39-spacer) array were effective. Our results suggest that there is great variation in the effective proportion of spacers across species, highlighting the need for fine-scale studies of CRISPR-array activity across diverse bacterial lineages.

microbiology↗

bioRxiv2026

Accurate, comprehensive gene annotation and ortholog identification across thousands of vertebrate genomes with TOGA2

Inferring orthologs and annotating coding genes remain central challenges in genomics, evident by the growing gap between assembled and annotated genomes. TOGA (Tool to infer Orthologs from Genome Alignments) addresses this challenge by integrating gene annotation and orthology inference. Here, we present TOGA2, the next generation of TOGA, which substantially improves annotation completeness, accuracy, scalability, and orthology inference. TOGA2 leverages exon-level orthology and introduces an exon-wise annotation procedure that reduces memory usage 513-fold and runtime 6.1-fold. We show that human-trained deep learning models for splice site prediction generalize across vertebrates. Integrating these predictions enables robust handling of evolutionary changes in exon-intron structure, including splice site shifts, intron deletions, and exonization of introns. A new gene tree reconciliation step refines orthology inference, and UTR annotation improves gene model completeness. Across mammals, birds, turtles, and percomorph fishes, TOGA2 annotations generally achieve higher gene completeness than transcriptome-informed RefSeq annotations. TOGA2 identifies previously unannotated exons in mouse, assigns informative gene symbols, and annotates V(D)J segments of antigen receptors. TOGA2 scales to thousands of genomes, which we demonstrate by generating comprehensive comparative genomics resources for 2,162 vertebrate assemblies, including gene annotations, ortholog sets, gene losses and duplications, retrogene candidates, and outputs supporting downstream analyses. Together, TOGA2 provides a scalable and versatile framework for comparative genomics that bridges the genome annotation gap.

genomics↗

bioRxiv2026

Impaired non-shivering thermogenesis in the desert-dwelling antelope ground squirrel

Adaptations in animals occupying environments of extreme cold or heat offer unique insights into thermoregulation. The antelope ground squirrel, a desert-dwelling rodent situated within a clade of hibernators, provides a notable example of these thermoregulatory extremes. As a non-hibernator closely related to hibernators, antelope ground squirrels may represent a rare case of trait reversal, with a striking ability to maintain core body temperatures exceeding 43{degrees}C while displaying poor tolerance to prolonged cold. Here, we explore the genetic and phenotypic basis of these unique traits by generating the first genome assembly for this species, which we use to conduct comparative genomics across the squirrel family. We complement this with acute and chronic cold-exposure experiments coupled with transcriptomic profiling of thermogenic organs: brown adipose tissue, white adipose tissue, and skeletal muscle. Together, these findings reveal a shift away from non-shivering thermogenesis toward metabolically demanding shivering thermogenesis, a perilous strategy for sustained heat generation.

evolutionary biology↗