Biology subjects

Thomas, P. K.

Publications and source records attributed to Thomas, P. K..

3 recordsLinked to original sources

bioRxiv2025

Persistent Cognitive Impairment and Bone Health Following Helium (4He) Ion Exposure: Implications for Space Travel

The current study investigated the long-term neurobehavioral and physiological effects of low-dose helium (4He; 250 MeV/n) ion exposure, a significant component of galactic cosmic radiation (GCR), on male Long Evans rats. Groups of rats were trained on the rodent psychomotor vigilance test (rPVT) and irradiated at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Following exposure, they were tested in the rPVT from 30 - 180 days, and assessed for social recognition memory at 30, 90, and 180 days. At each time point, blood and bone samples were collected for subsequent analysis. We found that acute exposure to 4He ions (25 cGy) significantly impaired sustained attention, resulting in increased lapses in attention, increased reaction time measures, and decreased correct responses. However, exposure to 5 cGy 4He ions only increased some reaction time measures in the rPVT. Both groups displayed impaired social recognition memory. When deficits were found, they persisted for 180 days post-exposure, showing no signs of recovery. Notably, impairments in sustained attention appeared to worsen over time. While these low exposure doses of 4He did not significantly alter overall bone mechanical properties, specific individual parameters of bone strength were affected, and age-related changes likely played a role in observed skeletal integrity changes. Furthermore, we identified significant correlations between circulating cytokines (TNF-, IL-1{beta}), undercarboxylated osteocalcin (ucOC) levels, and bone biomechanical properties with behavioral performances. These findings suggest the potential for these blood- and bone-based targets to serve as diagnostic biomarkers for radiation-induced neurobehavioral effects, opening avenues for future countermeasure development. The sustained and progressive nature of the neurobehavioral deficits observed underscores the critical need for effective countermeasures to protect astronaut health and performance during exploration-class missions.

animal behavior and cognition↗

bioRxiv2025

Hunting for extremophiles: a systematic screening of freshwater microalgae for tolerance to high pH and high alkalinity cultivation

Microalgae hold the potential to supply sustainable food, fuel, plastics, and chemicals at commercial scales. Cultivating microalgae at extreme pH (>10) and high alkalinity provides multiple benefits including 1) reducing the risk of contamination by undesired organisms and 2) enabling direct air capture of CO2, which expands the land area suitable for algae farming compared to using CO2 point sources alone. However, we currently have a limited understanding of which algal taxa can grow under these conditions. Therefore, we conducted a high-throughput screening of 49 freshwater microalgae strains, comprising 40 species, for their ability to grow in moderate (pH 8.5, 25 mM alkalinity), high (pH 10, 75 mM alkalinity), and extreme (pH 10, 150 mM alkalinity) cultivation environments. Our results show that moderate alkalinity tends to significantly increase algae growth (including potentially harmful strains). However, higher levels inhibit all but a small subset of green algae and cyanobacteria. Effects of salinity and alkalinity differed, indicating they are broadly decoupled. Our results identify new industrially relevant alkaline-tolerant strains, show that algae isolated from "normal" ecosystems can be extremophilic, and suggest that future bioprospecting efforts for alkaline-tolerant algae adapted to local climatic conditions could yield additional productivity gains for the algae industry. SynopsisWe tested if 49 distinct microalgae strains could grow in high pH environments and found new and productive alkaline-tolerant strains Abstract/TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/676395v1_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@63d59dorg.highwire.dtl.DTLVardef@5d597eorg.highwire.dtl.DTLVardef@9e9be7org.highwire.dtl.DTLVardef@10d9160_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2024

Botryococcus braunii reduces algal grazing losses to Daphnia and Poterioochromonas through both chemical and physical interference

Crop protection from algal grazers is a key area of concern, as grazing zooplankton and flagellates can decimate algal crops and impede economic viability of cultivation for biofuels and bioproducts. Inhibition of grazing by chemical and physical interference is one promising solution; however, there have been few empirical tests of this approach that use defense traits innate to algal crop species. Here we conduct an experiment to test whether the hydrocarbon excreting alga Botryococcus braunii can mitigate losses to grazing by two distinct grazers, Daphnia magna and Poterioochromonas malhamensis, due to both chemical inhibition and physical interference linked to large/inedible colonies. We show that chemical and physical defenses interactively reduce the total effect of grazing, thus significantly increasing the biomass of cultures of B. braunii and Nannochloropsis limnetica when either grazer is present. Specifically, B. braunii filtrate alone inhibits grazing and thus weakens top-down control of N. limnetica growth rates and final biomass by both grazers; B. braunii colonies alone also inhibit biomass losses; and the combination of filtrate and B. braunii colonies reveals an interactive effect of both chemical and physical defenses on grazing. Our study demonstrates how community engineering can identify synergies arising from algal cocultivation (e.g., by using industrially relevant strains for crop protection). Such ecological discoveries may help to reduce the costs of large-scale deployment of algal cultivation for sustainable foods, fuels, bioproducts (e.g., bioplastics), and carbon capture.

ecology↗