Biology subjects

Campos, D. P.

Publications and source records attributed to Campos, D. P..

2 recordsLinked to original sources

bioRxiv2025

Chromosome-level genome assembly of the Brazilian merganser (Mergus octosetaceus), a rare and elusive waterfowl species

BackgroundThe Brazilian merganser (Mergus octosetaceus) is a critically endangered bird, with fewer than 250 mature individuals remaining in fragmented populations of the Cerrado biome in Brazil. It is an ecologically demanding species that requires clear water of fast-flowing rivers for diving and foraging, and riverside cavities for nesting. Technical and logistical challenges have restricted sampling and research to few genetic studies so far. The genetic results consistently revealed a low genetic diversity and high inbreeding in the species. Besides, the lack of a reference genome has precluded deeper evolutionary and conservation genetic analyses for the species. ResultsWe generated the first high-quality, chromosome-level genome assembly for Mergus octosetaceus using PacBio HiFi long reads and Arima Hi-C data from a female specimen. The assembly is 1.25 Gb in length, is highly complete, scoring 98.9% of BUSCO completeness, and includes both sex chromosomes (Z and W). Annotated repetitive elements comprise 18.94% of the genome, with evidence of recent activity, particularly among LINEs and LTRs retrotransposons. We also produced and annotated the complete mitochondrial genome, identifying 37 genes and the control region. Comparative synteny analysis with other Anatidae species revealed strong chromosomal conservation, with several inversion events in macrochromosomes. Demographic history reconstruction indicated fluctuations in effective population size, with significant reductions overlapped by major temperature changes, highlighting potential climate sensitivity of this lineage. ConclusionThis reference genome provides a fundamental resource for M. octosetaceus, enabling insights into genome evolution, chromosomal dynamics within Anatidae, and past population history. It is a remarkable foundation for future research and conservation strategies for managing and restoring this critically endangered species.

evolutionary biology↗

bioRxiv2024

Challenges and promises in optimising a non-clinical protocol of intracerebroventricular human neural stem cell transplantation in ALS

Background and aimsNeural stem cell (NSC) transplantation holds promising therapeutic potential for neurodegenerative disorders like amyotrophic lateral sclerosis (ALS). However, pre-clinical studies and early-phase clinical trials have faced challenges hindering the effective clinical translation of this approach. Crucial hurdles include the side-effects of prolonged immunosuppression, concerns regarding cell origin and transplantation dosage, identification of the most appropriate therapeutic window, and invasiveness of surgical procedures. Here, we show challenges and promises in optimizing a non-clinical protocol to assess safety and efficacy of human NSC (hNSC) intracerebroventricular (ICV) transplantation for ALS. MethodsWe evaluated the safety of administering up to 1x106 hNSCs in immunodeficient mice and assessed their potential efficacy in reducing ALS hallmarks employing the SOD1G93A mouse model. Both, transient (15 days) and prolonged immunosuppression regimens, at low (15 mg/kg) and high (30 mg/kg) doses, were tested along with two different cell dosages (3x105 and 1x106). ResultsBilateral ICV injection of up to 1x106 hNSCs proved to be safe, with no evidence of tumor formation. At 40 days post-transplantation, hNSCs induced a trend toward delaying motor decline and reducing spinal cord (SC) microgliosis when transplanted under prolonged high-dose (30 mg/kg) immunosuppression. ConclusionsOur study suggests that: (i) a bilateral ICV transplantation of 1x106 hNSCs is safe and non-tumorigenic in immunodeficient hosts; (ii) sustained high-dose immunosuppression is essential for ensuring cell survival in immunocompetent mice; and (iii) hNSC transplantation may provide therapeutic benefits in ALS by delaying motor decline and reducing microgliosis. This study also highlights persisting hurdles that need to be further addressed, such as the aggressive murine immune response to exogenous cells.

neuroscience↗