Biology subjects

Shaffer, B.

Publications and source records attributed to Shaffer, B..

3 recordsLinked to original sources

bioRxiv2026

Retro-orbital blood sampling elicits short-term reductions in feeding behavior in western fence lizards (Sceloporus occidentalis)

Retro-orbital blood sampling, a method where the retro-orbital (post-orbital) sinus is punctured to draw blood, is often used in herpetological research given its ease, speed, and presumed minimal negative effect on the subject. Although literature establishing the method claims little to no impact on subjects, there exists little data explicitly testing the behavioral or welfare-related effects of this technique. We conducted a field experiment with western fence lizards (Sceloporus occidentalis) to address the potential impacts of retro-orbital blood sampling. Whereas handling the lizards had no demonstrable impact on lizard prey capture and feeding, there were significant short-term increases in time to initiate prey attack (attack latency) and time to successfully capture prey (feeding latency) in S. occidentalis immediately following blood draws. These increases diminished within 24 hours. Our experiments provide new evidence that this common blood sampling method reduces lizard feeding efficiency in the short-term. Researchers and welfare advocates may consider incorporating these findings into their research designs to optimize animal welfare and the generation of reliable ecological and behavioral data.

ecology↗

bioRxiv2025

PD-L1 ligation on NK cells induces a metabolic shift from glycolysis to fatty acid oxidation, enhancing tumor infiltration and control

PD-L1 blockade benefits even PD-L1-negative tumors, suggesting that non-tumor cells contribute to PD-L1 expression. Natural killer (NK) cells, vital mediators of innate immunity, vigorously express PD-L1 upon activation. We demonstrate that the ligation of PD-L1 on circulating and tumor-infiltrating NK cells with the therapeutic anti-PD-L1 antibody atezolizumab, soluble PD-1, or PD-1+ cells enhances NK cell-mediated tumor clearance via changes in metabolism, adhesion, and migration. PD-L1 engagement increases NK cell tumor infiltration via the CXCR3 pathway and cytoskeletal remodeling, supported by a metabolic shift from glycolysis to fatty acid oxidation (FAO). Loss of a key FAO enzyme, CPT1A, in NK cells abrogates the PD-L1-mediated anti-tumor effect, supporting a critical role for FAO in enhanced NK cell killing. The PD-L1-triggered shift away from glycolysis permits NK cells to remain highly effective at tumor killing in glucose-restricted TME. Taken together, PD-L1 ligation enhances NK cell cytotoxicity and tumor infiltration and contributes to NK resilience in challenging TME conditions, resulting in a more effective anti-tumor immunity. One sentence summaryPD-L1 engagement on NK cells enhances their tumor infiltration and cytotoxic activity by inducing a metabolic switch from glycolysis to fatty acid oxidation, enabling sustained function in the glucose-deprived tumor microenvironment.

immunology↗

bioRxiv2022

Managing invasive hybrids through habitat restoration in an endangered salamander system

Invasive species present one of the greatest threats to the conservation of biodiversity. When invasives hybridize with endangered native taxa, they introduce novel challenges ranging from the identification of hybrids in the field, to hybrid vigor and the erosion of species identity as genotypes are lost. Across a large swath of central California, a hybrid swarm consisting of admixed endangered California tiger salamanders ("CTS", Ambystoma californiense) and introduced barred tiger salamander (Ambystoma mavortium) has replaced native populations, threatening CTS with genomic extinction. Here we employ a large-scale, genomically-informed field ecological experiment to test whether habitat restoration can reinstate natural selection favoring native salamander genotypes. We constructed 14 large, semi-natural ponds and manipulated their hydroperiods to evaluate larval survival and mass at metamorphosis. Consistent with earlier work, we found overwhelming evidence of hybrid superiority which persisted across all hydroperiod treatments. Short duration ponds substantially reduced the mass and survival probability of both native and hybrid larvae, likely exerting strong selective pressure in the wild. We identified 86 candidate genes, representing 1.8% of 4,723 screened loci, that significantly responded to this hydroperiod-driven selection. In contrast to previous mesocosm-based studies, native CTS never exhibited greater fitness than hybrids, suggesting that hydroperiod management alone will not shift selection to favor native genotypes. However, shortening pond hydroperiod may represent a cost-effective strategy to limit the overall productivity of ponds with non-native genotypes, complimenting additional strategies such as targeted hybrid removal. At a broader level, our experimental approach leverages extensive ecological knowledge, modern genomic tools, and a naturalistic, in situ replicated design to critically evaluate and expand the potential toolkit that managers can use to address this, and other recalcitrant biological invasions. We believe that this strategy may be an important tool for managing the growing number of complex invasion scenarios threatening global biodiversity.

evolutionary biology↗