Biology subjects

Gedman, G. L.

Publications and source records attributed to Gedman, G. L..

5 recordsLinked to original sources

bioRxiv2025

Rapid Derivation of Cloning-Competent Cells from Peripheral Blood Advances Conservation Biobanking

I.Establishing viable cell lines from endangered species is essential for conservation, yet traditional fibroblast derivation from skin biopsies faces challenges including variable success rates, contamination risk, and extended culture timelines. We demonstrate that endothelial progenitor cells (EPCs) and pericytes isolated from peripheral blood represent superior alternatives for biobanking across three mammalian genera (Canis, Bison, and Equus). Blood-derived cells exhibited 2-3 fold faster doubling rates (15-20 hours versus >35 hours for fibroblasts) and reduced time to generate banked lines from 3-4 weeks to 1.5-2 weeks. Proteomic profiling of 32 canonical markers confirmed EPCs and pericytes represent distinct populations with lineage-specific molecular signatures. Optical genome mapping demonstrated equivalent genomic stability across all cell types with no detectable structural variants or aneuploidies. Critically, interspecific somatic cell nuclear transfer (iSCNT) experiments confirmed both EPCs and pericytes generate viable embryos with efficiency meeting or exceeding fibroblasts. Gray wolf blood-derived cells produced six viable fetuses with 15% implantation rate, while bison EPCs showed higher blastocyst formation (7%) than fibroblasts (3%) from the same individual. Blood collection during routine veterinary procedures offers minimally invasive sampling with reduced contamination compared to skin biopsies. These findings support integrating blood-derived cell banking into conservation programs, enabling opportunistic genetic preservation during standard management activities and expanding options for genetic rescue through assisted reproductive technologies.

cell biology↗

bioRxiv2023

Pronounced early differentiation underlies zebra finch gonadal germ cell development.

The diversity of germ cell developmental strategies has been well documented across many vertebrate clades. However, much of our understanding of avian primordial germ cell (PGC) specification and differentiation has derived from only one species, the chicken (Gallus gallus). Of the three major classes of birds, chickens belong to Galloanserae, representing less than 4% of species, while nearly 95% of extant bird species belong to Neoaves. This represents a significant gap in our knowledge of germ cell development across avian species, hampering efforts to adapt genome editing and reproductive technologies developed in chicken to other birds. We therefore applied single-cell RNA sequencing to investigate inter-species differences in germ cell development between chicken and zebra finch (Taeniopygia castanotis), a Neoaves songbird species and a common model of vocal learning. Analysis of early embryonic male and female gonads revealed the presence of two distinct early germ cell types in zebra finch and only one in chicken. Both germ cell types expressed zebra finch Germline Restricted Chromosome (GRC) genes, present only in songbirds among birds. One of the zebra finch germ cell types expressed the canonical PGC markers, as did chicken, but with expression differences in several signaling pathways and biological processes. The second zebra finch germ cell cluster was marked by proliferation and fate determination markers, indicating beginning of differentiation. Notably, these two zebra finch germ cell populations were present in both male and female zebra finch gonads as early as HH25. Using additional chicken developmental stages, similar germ cell heterogeneity was identified in the more developed gonads of females, but not males. Overall, our study demonstrates a substantial heterochrony in zebra finch germ cell development compared to chicken, indicating a richer diversity of avian germ cell developmental strategies than previously known.

cell biology↗

bioRxiv2022

Convergent gene expression highlights shared vocal motor microcircuitry in songbirds and humans

Vocal learning is a skilled motor behavior observed in several mammalian and avian species and is critical for human speech. While convergent gene expression patterns have highlighted similar primary motor and striatal pathways for vocal imitation in songbirds and humans, the extent of molecular and circuit convergence remains unresolved. Here we profiled the four principal song nuclei of the zebra finch (HVC, LMAN, RA, Area X) and their surrounding brain regions using RNA-Seq and compared them with specialized markers we identified for human speech brain regions. Expanding previous work, both songbird RA and HVC exhibited convergent specialized gene expression of [~]350 genes with human laryngeal sensorimotor cortex. The songbird HVCRA intratelencephalic (IT) neurons were the predominant cell type that was convergent with human, specifically layer 2/3 IT neurons, while the songbird RA extratelencephalic (ET) projection neurons exhibited convergent expression with human layer 5 ET projection neurons. The molecular specializations of both songbird LMAN and human Brocas area were more unique to each species. These findings demonstrate the extent of convergent molecular specializations in distantly related species for vocal imitation and emphasize important evolutionary constraints for this complex trait. One-Sentence SummaryOur data provide hundreds of candidate genes to study the molecular basis and evolution of song and speech across species.

neuroscience↗

bioRxiv2020

As above, so below: Whole transcriptome profiling supports the continuum hypothesis of avian dorsal and ventral pallium organization

Over the last two decades, beginning with the Avian Brain Nomenclature Forum in 2000, major revisions have been made to our understanding of the organization and nomenclature of the avian brain. However, there are still unresolved questions on avian pallial organization, particularly whether the cells above the ventricle represent different populations to those below it. Concerns included limited number of genes profiled, biased selection of genes, and potential independent origins of cell types in different parts of the brain. Here we test two competing hypotheses, using RNA sequencing to profile the transcriptomes of the major avian pallial subdivisions dorsal and ventral to the ventricle boundary, and a new zebra finch genome assembly containing about 22,000 annotated, complete genes. We found that the transcriptomes of neural populations below and above the ventricle were remarkably similar. What had been previously named hyperpallium densocellulare above the ventricle had nearly the same molecular profile as the mesopallium below it; the hyperpallium apicale above was highly similar to the nidopallium below; the primary sensory intercalated hyperpallium apicale above was most similar to the sensory population below, although more divergent than the other populations were to each other. These shared population expression profiles define unique functional specializations in anatomical structure development, synaptic transmission, signaling, and neurogenesis. These findings support the continuum hypothesis of avian brain subdivisions above and below the ventricle space, with the pallium as a whole consisting of four major cell populations instead of seven and has some profound implications for our understanding of vertebrate brain evolution.

neuroscience↗

bioRxiv2020

Towards complete and error-free genome assemblies of all vertebrate species

High-quality and complete reference genome assemblies are fundamental for the application of genomics to biology, disease, and biodiversity conservation. However, such assemblies are only available for a few non-microbial species1-4. To address this issue, the international Genome 10K (G10K) consortium5,6 has worked over a five-year period to evaluate and develop cost-effective methods for assembling the most accurate and complete reference genomes to date. Here we summarize these developments, introduce a set of quality standards, and present lessons learned from sequencing and assembling 16 species representing major vertebrate lineages (mammals, birds, reptiles, amphibians, teleost fishes and cartilaginous fishes). We confirm that long-read sequencing technologies are essential for maximizing genome quality and that unresolved complex repeats and haplotype heterozygosity are major sources of error in assemblies. Our new assemblies identify and correct substantial errors in some of the best historical reference genomes. Adopting these lessons, we have embarked on the Vertebrate Genomes Project (VGP), an effort to generate high-quality, complete reference genomes for all ~70,000 extant vertebrate species and help enable a new era of discovery across the life sciences.

genomics↗