Biology subjects

Freitas, M. B.

Publications and source records attributed to Freitas, M. B..

3 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↗

bioRxiv2023

Acute exposure of fruit bats to low concentrations of heavy metals affects oxidative stress markers

Cadmium (Cd), chromium (Cr), lead (Pb), and nickel (Ni) are heavy metals and common environmental pollutants. We aimed to investigate heavy metals effects on fruit-bats organs. Adult males (Artibeus lituratus) were captured and exposed to heavy metals (1.5 mg/kg). The Integrated Biomarker Response helped us understand the interrelationship in a multi-biomarker global approach to oxidative stress. The liver was more sensitive to Ni and Pb than Cd and Cr. In the kidney, Pb did not cause hazardous effects, unlike the other metals. In testes, Ni doubled damage levels compared to the other metals. Ni did not cause serious effects in muscles, which was more sensitive to Pb and Cd than to Cr. The brain was more susceptible to Pb and Ni than Cr and Cd. We observed that acute doses, even in low concentrations, are deleterious to fruit-bats. We propose the following order of metal toxicity: Ni> Pb> Cd> Cr. SUMMARY STATEMENTThe investigation of heavy metals toxicity in fruit bats reveals differential sensitivities of organ and highlights the harmful effects of acute exhibitions even at low concentrations.

pharmacology and toxicology↗

bioRxiv2020

Impacts of the Samarco tailing dam collapse on metals and arsenic concentration in freshwater fish muscle from Doce River, southeastern Brazil

On November 2015, Samarco tailings dam in Mariana MG, Brazil, collapsed, releasing 62 million tons of tailings that advanced through 668 km of the Doce River and adjacent floodplain. Although being the worst environmental disaster in Brazil, little is known about consequences to aquatic biota. Here we evaluate the effects of the tailings mudflow on metal and arsenic concentration in fish and how concentration correlates with water and fish characteristics. We quantified semitotal amounts of Ag, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in fish muscle tissue using ICP-MS in 255 individuals (34 species) sampled in unaffected and affected along the Doce River basin. Arsenic and Hg were higher in fish from affected sites, likely due to turbulent mixing of previously sedimented material by the giant tailings wave. Silver and Zn concentrations were higher in unaffected sites. Arsenic concentration in Geophagus brasiliensis decreased with increasing fish weight. Copper and Zn decreased with increasing fish weight considering the whole assembly of fish. The tailings mudflow increased water conductivity and conductivity increased Al concentration in fish, so we expected a larger Al concentration in fishes from affected sites. However, the observed Al concentration in fishes from affected sites was lower than expected by water conductivity. Thus, the tailings mudflow reduced Al uptake or accumulation in fishes. Mercury decreased with increasing water conductivity in both unaffected and affected sites considering all species and in G. brasiliensis alone. Despite the relatively low concentration range of metals and As found in fish, fishes from sites affected by the iron ore tailings mudflow showed higher As and Hg concentration, compared to fishes from unaffected sites. The higher As and Hg in affected sites require further detailed monitoring to ensure safeguards of human health by fishing activity along the Doce River.

ecology↗