Biology subjects

Schaffer, J.

Publications and source records attributed to Schaffer, J..

4 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

Kruppel-like factor 1 acts upstream of the SKN-1/Nrf transcription factors to modulate oxidative stress, lipid homeostasis and longevity

Maintenance of lipid and redox homeostasis are essential for stress resistance and longevity, but the transcriptional networks coordinating these processes remain incompletely understood. In Caenorhabditis elegans, the transcription factors SKN-1A/Nrf1 and SKN-1C/Nrf2 mediate distinct stress responses that promote proteostasis, lipid homeostasis, and oxidative stress. Here we identify the Kruppel-like factor KLF-1 as a critical upstream regulator of both SKN-1A and SKN-1C. We show that KLF-1 is required for the oxidative stress resistance and longevity of germline-deficient animals. Genetic interaction studies showed that KLF-1 acts in parallel to the lipogenic regulator Sterol regulatory element-Binding Protein 1 (SBP-1/SREBP1), whereas the related KLF-2 exerts opposing effects on lipid accumulation through SBP-1. Together, these findings place KLF-1 and KLF-2 within a transcriptional network that integrates lipid metabolism, oxidative stress responses, and aging. This work uncovers a conserved regulatory network linking KLFs and SKN-1/Nrf transcription factors in the maintenance of lipid homeostasis and longevity assurance.

cell biology↗

bioRxiv2020

Simple fence modification increases floodplain land movement prospects for freshwater turtles

Feral pigs predate on freshwater turtles and damage wetland habitats in the process. Installing fences successfully averts access and damage, however, they become a barrier for freshwater turtles requiring land access during migration. We collected 161 turtles (Chelodina rugosa, Emydura subglobosa worrelli, Myuchelys latisternum) from twenty floodplain and riverine wetlands during post-wet (June-August) and late-dry season (November-December) surveys (2015-2018) in northern Australia. Wetlands were either fenced (150 x 150mm square, 1.05m high wire mesh) or not around the wet perimeter. Nine-seven percent of individuals caught in either fenced or unfenced wetlands had a shell carapace width greater than mesh width, of these 44 (46%) were captured inside fenced wetlands, while 50 were caught in unfenced wetlands. The remaining 35 were smaller than 150mm and would easily pass through fence mesh. Sixty-five turtles partook in a fencing manipulative experiment. Turtles with carapace widths wider than mesh often successfully escaped through fences by lifting one side of their shell and passing diagonally. In a second experiment where a piece of vertical wire (1500mmx300mm) was removed, turtles located gates after prospecting and trying to fit through meshing areas that were too small to pass through. Nine-two percent of turtles were able to locate and pass through gates, while 8% failed to locate a gate after 2 hours. Three turtles that did not use gates, and seemed to give up and dug into the grass. Gates applied every 4m showed an 83% passage rate, every 2m was 91%, and while every 1m was 100%. Combing field and manipulative experiments revealed that large turtles will prospect and move along a fence until they find suitable passage. Applying turtle gates every 1-4m allows almost 100% passage, and if strategically applied in travel corridors, would minimize the need for large-scale clipping efforts around entire wetlands.

ecology↗

bioRxiv2019

Feral pig exclusion fencing provides limited fish conservation value on tropical floodplains

Efforts to protect and restore tropical wetlands impacted by feral pigs (Sus scrofa) in northern Australia have more recently included exclusion fences, an abatement response proposing fences improve wetland condition by protecting habitat for fish production and water quality. Here we tested: 1) whether the fish assemblage are similar in wetlands with and without fences; and 2) whether specific environmental processes influence fish composition differently between fenced and unfenced wetlands. Twenty-one floodplain and riverine wetlands in the Archer River catchment (Queensland) were surveyed during post-wet (June-August) and late-dry season (November-December) in 2016, 2017 and 2018, using a fyke soaked overnight (~14-15hrs). A total of 6,353 fish representing twenty-six species from 15 families were captured. There were no multivariate differences in fish assemblages between seasons, years and for fenced and unfenced wetlands (PERMANOVA, Pseduo-F <0.58, P<0.68). Late-dry season fish were considerably smaller compared to post-wet season: a strategy presumably to maximise rapid disposal following rain. At each wetland a calibrated Hydrolab was deployed (between 2-4 days, with 20min logging) in the epilimnion (0.2m), and revealed distinct diel water quality cycling of temperature, dissolved oxygen and pH (conductivity represented freshwater wetlands) which was more obvious in the late-dry season survey, because of extreme summer conditions. Water quality varied among wetlands, in terms of the daily amplitude, and extent of daily photosynthesis recovery, which highlights the need to consider local site conditions rather than applying general assumptions around water quality conditions for these types of wetlands examined here. Though many fish access (fenced and unfenced) wetlands during wet season connection, the seasonal effect of reduced water level conditions seems to be more over-improvised compared to whether fences are installed or not, as all wetlands supported few, juvenile, or no fish species because they had dried completed regardless of whether fences were present or not.

ecology↗