Biology subjects

Tucker, C. S.

Publications and source records attributed to Tucker, C. S..

4 recordsLinked to original sources

bioRxiv2026

Drought and Productivity Trends in Freshwater Flooded Forest Swamps in the North American Coastal Plain

Climate change has resulted in an increase in drought conditions within the southeastern United States, impacting a variety of ecosystems and species, including the freshwater flooded forest swamps of the North American Coastal Plain (NACP). With the threat of drought leading to a decline in wetlands and shifts in seasonality patterns in the NACP, there is significant concern about the effects of a drying climate on the net primary productivity of bald cypress-tupelo swamps and the potential for ecosystem degradation or conversion. This study seeks to understand the relationship between the net primary productivity of wetlands dominated by bald cypress-tupelo swamps and drought conditions. We used Moderate Resolution Imaging Spectroradiometer (MODIS) imagery from 2000 to 2024, taken from the 500 largest flooded forest swamps in the southeastern USA using Google Earth Engine, to track the changes in productivity of these swamps over time. The trends in MODIS Fraction of Absorbed Photosynthetically Active Radiation (FPAR), Normalized Difference Vegetation Index (NDVI), and Enhanced Vegetation Index (EVI) were compared against three common drought indices using seasonal decomposition and linear regression along with local bivariate spatial associations. We found that while there were small global correlations between drought and productivity metrics, the impact of droughts on these swamps is highly spatially variable, with specific geographical regions displaying differing impacts of drought and precipitation levels on the vegetation productivity. Coastal and southern regions, including the states of Texas, Florida, and Louisiana, are experiencing a decrease in precipitation but have mixed productivity trends. Meanwhile, more inland and coastal northern areas display an increase in precipitation and wetness. Overall, our results suggest that cypress-tupelo swamp productivity varies based on a variety of factors, including, but not limited to, precipitation and drought levels, but some areas may be at risk of further degradation due to drought under future climate change. Further research is encouraged to fully understand vegetation productivity in relation to environmental conditions in individual cypress-tupelo swamps.

ecology↗

bioRxiv2021

Macrophages stimulate epicardial VEGFaa to trigger cardiomyocyte proliferation in larval zebrafish heart regeneration

Cardiac injury induces a sustained macrophage response in both zebrafish and mammals. Macrophages perform a range of both beneficial and detrimental functions during mammalian cardiac repair, yet their precise roles in zebrafish cardiac regeneration are not fully understood. Here we characterise cardiac regeneration in the rapidly regenerating larval zebrafish laser injury model and use macrophage ablation and macrophage-null irf8 mutants to define the role of macrophages in key stages of regeneration. Live heartbeat-synchronised imaging and RNA sequencing revealed an early proinflammatory phase, marked by tnfa+ macrophages, which then resolved to an anti-inflammatory, profibrotic phase. Macrophages were required for cardiomyocyte proliferation but not for functional or structural recovery following injury. Importantly, we found that macrophages are specifically recruited to the epicardial-myocardial niche, triggering the expansion of the epicardium which upregulates VEGFaa expression to induce cardiomyocyte proliferation. Hence, revealing a novel mechanism by which macrophages facilitate cardiac regeneration.

immunology↗

bioRxiv2019

Monitoring contractility in single cardiomyocytes and whole hearts with bio-integrated microlasers

Cardiac regeneration and stem cell therapies depend critically on the ability to locally resolve the contractile properties of heart tissue1,2. Current regeneration approaches explore the growth of cardiac tissue in vitro and the injection of stem cell-derived cardiomyocytes3-6 (CMs) but scientists struggle with low engraftment rates and marginal mechanical improvements, leaving the estimated 26 million patients suffering from heart failure worldwide without effective therapy7-9. One impediment to further progress is the limited ability to functionally monitor injected cells as currently available techniques and probes lack speed and sensitivity as well as single cell specificity. Here, we introduce microscopic whispering gallery mode (WGM) lasers into beating cardiomyocytes to realize all-optical recording of transient cardiac contraction profiles with cellular resolution. The brilliant emission and high spectral sensitivity of microlasers to local changes in refractive index enable long-term tracking of individual cardiac cells, monitoring of drug administration, and accurate measurements of organ scale contractility in live zebrafish. Our study reveals changes in sarcomeric protein density as underlying factor to cardiac contraction which is of fundamental importance for understanding the mechano-biology of cardiac muscle activation. The ability to non-invasively assess functional properties of transplanted cells and engineered cardiac tissue will stimulate the development of novel translational approaches and the in vivo monitoring of physiological parameters more broadly. Likewise, the use of implanted microlasers as cardiac sensors is poised to inspire the adaptation of the most advanced optical tools known to the microresonator community, like quantum-enhanced single-molecule biosensing or frequency comb spectroscopy10.

biophysics↗

bioRxiv2019

Hybrid optical gating for long-term 3D time-lapse imaging of the beating embryonic zebrafish heart

Three-dimensional fluorescence time-lapse imaging of structural, cellular and sub-cellular processes in the beating heart is an increasingly achievable goal using the latest imaging and computational techniques. However, previous approaches have had significant limitations. Temporarily arresting the heart using drugs disrupts the hearts physiological state, and the use of ultra-high frame-rates for fluorescence image acquisition causes phototoxic cell damage. Real-time triggered imaging, synchronized to a specific phase in the cardiac-cycle, can computationally "freeze" the heart to acquire the minimal number of fluorescence images required for 3D time-lapse imaging. However, until now no solution has been able to maintain phase-lock to the same point in the cardiac cycle for more than about one hour. Our new hybrid optical gating system maintains phase-lock for up to 24 h, acquiring synchronized 3D+time video stacks of the unperturbed heart in vivo. This approach has enabled us to observe detailed developmental, structural, cellular and subcellular processes, including live cell division and cell fate tracking, in the embryonic zebrafish heart using transgenic fish lines expressing cell-specific fluorophores. We show that our approach not only provides high spatial and temporal resolution 3D-imaging, but also avoids phototoxic injury, where alternative approaches induce measurable harm. This provides superb cellular and subcellular imaging of the heart while it is beating in its normal physiological state, and opens up new and exciting opportunities for further study in the heart and other moving cellular and subcellular structures in vivo.

bioinformatics↗