Selected Grantee Publications
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- Aquatic Vertebrate Models
- Swine Models
Whole-Organism 3D Quantitative Characterization of Zebrafish Melanin by Silver Deposition Micro-CT
Katz et al., eLife. 2021.
https://www.biorxiv.org/content/10.1101/2021.03.11.434673v1
This research team combined micro-computed tomography (CT) with a novel application of ionic silver staining to characterize melanin distribution in whole zebrafish larvae. The resulting images enabled whole-body, computational analyses of regional melanin content and morphology. Normalized micro-CT reconstructions of silver-stained fish consistently reproduced pigment patterns seen by light microscopy and allowed direct quantitative comparisons of melanin content. Silver staining of melanin for micro-CT provides proof-of-principle for whole-body, 3D computational phenomic analysis of a specific cell type at cellular resolution. Advances such as this in whole-organism, high-resolution phenotyping provide superior context for studying the phenotypic effects of genetic, disease, and environmental variables. Supported by ORIP (R24OD018559).
MIC-Drop: A Platform for Large-scale In Vivo CRISPR Screens
Parvez et al., Science. 2021.
https://pubmed.ncbi.nlm.nih.gov/34413171/
CRISPR screens in animals are challenging because generating, validating, and keeping track of large numbers of mutant animals is prohibitive. These authors introduce Multiplexed Intermixed CRISPR Droplets (MIC-Drop), a platform combining droplet microfluidics, single-needle en masse CRISPR ribonucleoprotein injections, and DNA barcoding to enable large-scale functional genetic screens in zebrafish. In one application, they showed that MIC-Drop could identify small-molecule targets. Furthermore, in a MIC-Drop screen of 188 poorly characterized genes, they discovered several genes important for cardiac development and function. With the potential to scale to thousands of genes, MIC-Drop enables genome-scale reverse genetic screens in model organisms. Supported by ORIP (R24OD017870), NIGMS, and NHLBI.
The Bowfin Genome Illuminates the Developmental Evolution of Ray-Finned Fishes
Thompson et al., Nature Genetics. 2021.
https://www.nature.com/articles/s41588-021-00914-y
The bowfin (Amia calva) is a ray-finned fish that possesses a unique suite of ancestral and derived phenotypes, which are key to understanding vertebrate evolution. The phylogenetic position of bowfin as a representative of neopterygian fishes, its archetypical body plan and its unduplicated and slowly evolving genome make bowfin a central species for the genomic exploration of ray-finned fishes. Here the authors present a chromosome-level genome assembly for bowfin that enables gene-order analyses, settling long-debated neopterygian phylogenetic relationships. These resources connect developmental evolution among bony fishes, further highlighting the bowfin's importance for illuminating vertebrate biology and diversity in the genomic era. Supported by ORIP (R01OD011116).
TGF-β1 Signaling Is Essential for Tissue Regeneration in the Xenopus Tadpole Tail
Nakamura et al., Biochemical and Biophysical Research Communications. 2021.
https://www.sciencedirect.com/science/article/pii/S0006291X21008731
Amphibians, such as Xenopus tropicalis, exhibit a remarkable capacity for tissue regeneration after traumatic injury. Nakamura et al. show that inhibition of TGF-β1 function prevents tail regeneration in Xenopus tropicalis tadpoles. CRISPR-mediated knock-out (KO) of tgfb1 retards tail regeneration; the phenotype of tgfb1 KO tadpoles can be rescued by injection of tgfb1 mRNA. Cell proliferation, critical for tissue regeneration, is downregulated in tgfb1 KO tadpoles; tgfb1 KO reduces the expression of phosphorylated Smad2/3 (pSmad2/3). These results show that TGF-β1 regulates cell proliferation through the activation of Smad2/3. They propose that TGF-β1 plays a critical role in TGF-β receptor-dependent tadpole tail regeneration in Xenopus. Supported by ORIP (P40OD010997, R24OD030008).
Deep Learning-Based Framework for Cardiac Function Assessment in Embryonic Zebrafish from Heart Beating Videos
Naderi et al., Computers in Biology and Medicine. 2021.
https://www.sciencedirect.com/science/article/pii/S0010482521003590
Zebrafish is a powerful model system for a host of biological investigations, cardiovascular studies, and genetic screening. However, the current methods for quantifying and monitoring zebrafish cardiac functions involve tedious manual work and inconsistent estimations. Naderi et al. developed a Zebrafish Automatic Cardiovascular Assessment Framework (ZACAF) based on a U-net deep learning model for automated assessment of cardiovascular indices, such as ejection fraction (EF) and fractional shortening (FS) from microscopic videos of wildtype and cardiomyopathy mutant zebrafish embryos. The framework could be widely applicable with any laboratory resources, and the automatic feature holds promise to enable efficient, consistent, and reliable processing and analysis capacity. Supported by ORIP (R44OD024874)
Loss of Gap Junction Delta-2 (GJD2) Gene Orthologs Leads to Refractive Error in Zebrafish
Quint et al., Communications Biology. 2021.
https://pubmed.ncbi.nlm.nih.gov/34083742/
Myopia is the most common developmental disorder of juvenile eyes. Although little is known about the functional role of GJD2 in refractive error development, the authors find that depletion of gjd2a (Cx35.5) or gjd2b (Cx35.1) orthologs in zebrafish cause changes in eye biometry and refractive status. Their immunohistological and scRNA sequencing studies show that Cx35.5 (gjd2a) is a retinal connexin; its depletion leads to hyperopia and electrophysiological retina changes. They found a lenticular role; lack of Cx35.1 (gjd2b) led to a nuclear cataract that triggered axial elongation. The results provide functional evidence of a link between gjd2 and refractive error. Supported by ORIP (R24OD026591), NIGMS, and NINDS.
Algorithms Underlying Flexible Phototaxis in Larval Zebrafish
Chen et al., Journal of Experimental Biology. 2021.
https://pubmed.ncbi.nlm.nih.gov/34027982/
Given that physiological and environmental variables undergo constant fluctuations over time, how do biological control systems maintain control over these values? The authors demonstrate that larval zebrafish use phototaxis to maintain environmental luminance at a set point, that the value of this set point fluctuates on a time scale of seconds when environmental luminance changes, and it is determined by calculating the mean input across both sides of the visual field. Feedback from the surroundings drives allostatic changes to the luminance set point. The authors describe a novel behavioral algorithm with which larval zebrafish exert control over a sensory variable. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Mineralocorticoid Receptor Blockade Normalizes Coronary Resistance in Obese Swine Independent of Functional Alterations in Kv Channels
Goodwill et al., Basic Research in Cardiology. 2021.
https://pubmed.ncbi.nlm.nih.gov/34018061/
Impaired coronary microvascular function (e.g., reduced dilation and coronary flow reserve) predicts cardiac mortality in obesity. Mineralocorticoid receptor (MR) antagonism improves coronary microvascular function in obese humans and animals. Inhibition of Kv channels reduced coronary blood flow and augmented coronary resistance under baseline conditions in lean but not obese swine and had no impact on hypoxemic coronary vasodilation. MR blockade prevented obesity-associated coronary arteriolar stiffening independent of cardiac capillary density and changes in cardiac function. These data indicate that chronic MR inhibition prevents increased coronary resistance in obesity independent of Kv channel function and is associated with mitigation of obesity-mediated coronary arteriolar stiffening. Supported by ORIP (U42OD011140, S10OD023438), NHLBI, and NIBIB.
Cell-Specific Transcriptional Control of Mitochondrial Metabolism by TIF1γ Drives Erythropoiesis
Rossmann et al., Science. 2021.
https://pubmed.ncbi.nlm.nih.gov/33986176/
Transcription and metabolism both influence cell function but dedicated transcriptional control of metabolic pathways that regulate cell fate has rarely been defined. The authors discovered that inhibition of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) rescues erythroid differentiation in bloodless zebrafish moonshine (mon) mutant embryos defective for transcriptional intermediary factor 1 gamma (tif1γ). Upon tif1γ loss, CoQ levels are reduced, and a high succinate/α-ketoglutarate ratio leads to increased histone methylation. A CoQ analog rescues mon's bloodless phenotype. These results demonstrate that mitochondrial metabolism is a key output of a lineage transcription factor that drives cell fate decisions in the early blood lineage. Supported by ORIP (R24OD017870), NIGMS, NHLBI, and NCI.
Identification of Basp1 as a Novel Angiogenesis-regulating Gene by Multi-Model System Studies
Khajavi et al., FASEB Journal. 2021.
https://pubmed.ncbi.nlm.nih.gov/33899275/
The authors previously used genetic diversity in inbred mouse strains to identify quantitative trait loci (QTLs) responsible for differences in angiogenic response. Employing a mouse genome-wide association study (GWAS) approach, the region on chromosome 15 containing Basp1 was identified as being significantly associated with angiogenesis in inbred strains. To investigate its role in vivo, they knocked out basp1 in transgenic kdrl:zsGreen zebrafish embryos using a widely adopted CRISPR-Cas9 system. They further showed that basp1 promotes angiogenesis by upregulating β-catenin gene and the Dll4/Notch1 signaling pathway. These results provide the first in vivo evidence to indicate the role of basp1 as an angiogenesis-regulating gene. Supported by ORIP (R24OD017870) and NEI.