Biology subjects

Cardoso, T.

Publications and source records attributed to Cardoso, T..

4 recordsLinked to original sources

bioRxiv2024

Undergraduate research project uncovers a novel strain of amphibian chytrid fungus in the Northeastern United States

Investigation of the genetic variation of Batrachochytrium dendrobatidis (Bd or chytrid fungus) in New Hampshire (NH) in the northeastern U.S. has shown the presence of genetic mutations which are currently undocumented in the literature. DNA was collected as part of a long-term monitoring project in New Hampshire to test for the presence of Bd in amphibian populations. In this monitoring project, we are detecting the presence of Bd in multiple populations, but the observed amphibians do not appear to have increased mortality or other symptoms related to the fungus. To further investigate the strain of Bd affecting NH amphibians, we sequenced samples that were collected in 2019, as part of your yearly monitoring effort. Utilizing the Basic Local Alignment Search Tool (BLAST) and sequences available on GenBank, we found that there are two different strains of chytrid in the observed NH amphibians. These strains are similar to strains noted previously in New England, but exhibit unique point mutations and in one case, a deletion. These variations could affect the impact that Bd has on amphibians in this region, and therefore could contribute to a better understanding of the variation in strains of chytrid and how they impact amphibian populations around the world. This study highlights the importance of monitoring efforts conducted at smaller, non-research institutions and we encourage other small institutions to take up similar monitoring efforts for Bd or other national or global conservation concerns.

ecology↗

bioRxiv2019

Single Cell Gene Expression Analysis Reveals Human Stem Cell-Derived Graft Composition in a Cell Therapy Model of Parkinson’s Disease

Since the pioneering studies using fetal cell transplants in Parkinsons disease (PD), brain repair by cell replacement has remained a long-standing and realistic goal for the treatment of neurodegenerative disorders including PD. Authentic and functional midbrain dopamine (DA) neurons can now be generated from human pluripotent stem cells (hPSCs) via a floor plate intermediate1,2, and these cell preparations are both safe and functional when transplanted to animal models of PD3. However, although resulting grafts from fetal brain tissue and hPSCs contain large numbers of desired DA neurons, these therapeutic cells are a minor component of the grafts. Moreover, the cellular composition of the graft has remained difficult to assess due to limitations in histological methods that rely on pre-conceived notions concerning cell types. Here, we used single cell RNA sequencing (scRNA-seq) combined with comprehensive histological analyses to characterize intracerebral grafts from ventral midbrain (VM)-patterned human embryonic stem cells (hESCs) and VM fetal tissue after long-term survival and functional maturation in a pre-clinical rat model of PD. The analyses revealed that while both cell preparations gave rise to neurons and astrocytes, oligodendrocytes were only detected in grafts of fetal tissue. On the other hand, a cell type closely resembling a class of newly identified perivascular-like cells was identified as a unique component of hESC-derived grafts. The presence of these cells was confirmed in transplants from three different hESC lines, as well as from iPSCs. Thus, these experiments have addressed one of the major outstanding questions in the field of cell replacement in neurological disease by revealing graft composition and differences between hESC- and fetal cell-derived grafts, which can have important implications for clinical trials.

neuroscience↗

bioRxiv2018

Barcoded Rational AAV Vector Evolution enables systematic in vivo mapping of peptide binding motifs

Engineering of Adeno-associated viral (AAV) vector capsids through directed evolution has been used to generate novel capsids with altered tropism and function1-9. This approach, however, involves a selection process that requires multiple generations of screenings to identify real functional capsids2-4. Due to the random nature of this process, it is also inherently unreproducible, and the resulting capsid variants provide little mechanistic insights into the molecular targets engaged. To overcome this, we have developed a novel method for rational capsid evolution named Barcoded Rational AAV Vector Evolution (BRAVE). The key to this method is a novel viral production approach where each virus particle displays a protein-derived peptide on the surface which is linked to a unique barcode in the packaged genome10. Through hidden Markov model-based clustering11, we were able to identify novel consensus motifs for cell-type specific retrograde transport in neurons in vivo in the brain. The BRAVE approach enables the selection of novel capsid structures using only a single-generation screening. Furthermore, it can be used to map, with high resolution, the putative binding sequences of large protein libraries.

neuroscience↗

bioRxiv2018

A taxonomically-restricted Uric Acid transporter provides insight into antioxidant equilibrium

Nucleobase-Ascorbate Transporter (NAT) family includes ascorbic acid, nucleobases and uric acid transporters, with a broad evolutionary distribution. In vertebrates, four members have been previously recognized, the ascorbate transporters Slc23a1 and Slc3a2, the nucleobase transporter Slc23a4 and an orphan transporter SLC23A3. Here we identify a fifth member of the vertebrate slc23 complement (slc23a5), expressed in neopterygians (gars and teleosts) and amphibians, and clarify the evolutionary relationships between the novel gene and known slc23 genes. Further comparative analysis puts forward uric acid as the preferred substrate for Slc23a5. Gene expression quantification suggests kidney and testis as major expression sites in Xenopus tropicalis (western clawed frog) and Danio rerio (zebrafish). Additional expression in brain was detected in D. rerio, while in the Neoteleostei Oryzias latipes (medaka) slc23a5 expression is restricted to brain. The biological relevance of the retention of an extra transporter in fish and amphibians is examined: with respect to the (1) antioxidant role of uric and ascorbic acid in seminal fluid and brain, (2) the ability to endogenously synthesize ascorbic acid and (3) the morphological adaptations of the male urogenital system.

evolutionary biology↗