Biology subjects

Jones, K. G.

Publications and source records attributed to Jones, K. G..

4 recordsLinked to original sources

bioRxiv2026

The distribution of particle-associated Prochlorococcus across the global oceans

The picocyanobacterium Prochlorococcus is a fundamental contributor to ocean primary productivity. While its free-living population has been extensively studied, primarily using flow cytometric analyses, the size and distribution of its particle-associated population is not well understood. Using filter fractionated samples from cruises in the Pacific Ocean, Atlantic Ocean, and Mediterranean Sea, we generated metagenomic data using internal standards, yielding absolute genome equivalent counts of Prochlorococcus cells in different size fractions. We used these data to model a relationship between relative and absolute genome equivalent counts, yielding a correction factor that we validated using published datasets. We then applied the correction factor to size-fractionated global metagenomic data from the TARA Oceans Project, which has widespread Prochlorococcus cells in size fractions >1.6 m throughout the transects, to calculate the fraction of the total Prochlorococcus population in large size fractions. The ''particle-associated'' population fraction increased with net primary productivity. Dissolved inorganic carbon was also directly correlated with increased particle association, which, combined with other evidence, could indicate an association with upwelling. We also examined the relationship between particle-associated population and carbon export at 150 m by incorporating published estimates of carbon flux based on TARA optical scattering data. This study highlights the potential importance of particle-associated Prochlorococcus to carbon flux in marine ecosystems and offers a way to convert relative to absolute genome equivalents of microorganisms in archival metagenomic datasets.

ecology↗

bioRxiv2025

The temperate coral Astrangia poculata maintains acid-base homeostasis through heat stress

Heat stress can disrupt acid-base homeostasis in reef-building corals and other tropical cnidarians, often leading to cellular acidosis that can undermine organismal function. Temperate cnidarians experience a high degree of seasonal temperature variability, leading us to hypothesize that temperate taxa have more thermally robust pH homeostasis than their tropical relatives. To test this, we investigated how elevated temperature affects intracellular pH and calcification in the temperate coral Astrangia poculata. Clonal pairs were exposed to elevated (30{degrees}C) or control (22{degrees}C) temperatures for 17 days. Despite causing damage to host tissues and symbiont cells, elevated temperature did not affect intracellular pH or inhibit calcification in A. poculata. These responses contrast with those of tropical cnidarians, which experience cellular acidification and decreased growth during heat stress. A. poculata therefore appears to have thermally resilient cellular acid-base homeostasis mechanisms, possibly due to adaptation to large seasonal temperature variations. However, we also observed tissue damage and lower egg densities in heat-treated individuals, suggesting that increasingly severe marine heatwaves can still threaten temperate coral fitness. These results provide insight into corals nuanced adaptive capacity across latitudes and biological scales.

ecology↗

bioRxiv2025

Biofilm formation and dynamics in the marine cyanobacterium Prochlorococcus

The picocyanobacterium Prochlorococcus is responsible for [~]10% of annual marine carbon fixation and plays a role in the global carbon budget. While these phototrophs are primarily considered free-living and neutrally buoyant in the euphotic zone, we observe that they can form biofilms on diverse substrates. This trait is conserved across Prochlorococcus ecotypes, and populations continuously transition between planktonic and biofilm states via a non-genetic heritable mechanism. Throughout their growth, cells in biofilms retain a reversible, dynamic attachment state, and measurements of growth, photosynthesis, and respiration rates reveal that cells in biofilms exude more organic carbon than their planktonic counterparts. Estimates of the fraction of Prochlorococcus cells attached to particles in the ocean reveal that a significant adherent population exists throughout the euphotic and mesopelagic zones. This work describes a new dimension of Prochlorococcuss ecological niche and suggests a role in carbon export to the deep sea.

ecology↗

bioRxiv2023

Heat stress disrupts acid-base homeostasis independent of symbiosis in the model cnidarian Exaiptasia diaphana

Heat stress threatens the survival of symbiotic cnidarians by causing their photosymbiosis to break down in a process known as bleaching. The direct effects of temperature on cnidarian host physiology remain difficult to describe because heat stress depresses symbiont performance, leading to host stress and starvation. The symbiotic sea anemone Exaiptasia diaphana provides an opportune system in which to disentangle direct vs. indirect effects of heat stress on the host, since it can survive indefinitely without symbionts. Here, we tested the hypothesis that heat stress directly influences cnidarian physiology by comparing symbiotic and aposymbiotic individuals of a clonal strain of E. diaphana. We exposed anemones to a range of temperatures (ambient, +2{degrees}C, +4{degrees}C, +6{degrees}C) for 15-18 days, then measured their symbiont population densities, autotrophic carbon assimilation and translocation, photosynthesis, respiration, and host intracellular pH (pHi). Anemones with initially high symbiont densities experienced dose-dependent symbiont loss with increasing temperature, resulting in a corresponding decline in host photosynthate accumulation. In contrast, anemones with low initial symbiont densities did not lose symbionts or assimilate less photosynthate as temperature increased, similar to the response of aposymbiotic anemones. Interestingly, pHi decreased in anemones at higher temperatures regardless of symbiont presence, cell density, or photosynthate translocation, indicating that heat stress disrupts cnidarian acid-base homeostasis independent of symbiosis dysfunction, and that acid-base regulation may be a critical point of vulnerability for hosts of this vital mutualism. Summary StatementWarming oceans threaten marine invertebrates. We found that heat disrupts acid-base homeostasis in a model symbiotic sea anemone regardless of symbiont presence or function, highlighting bleaching-independent effects of climate change.

physiology↗