Biology subjects

Baird, M.

Publications and source records attributed to Baird, M..

6 recordsLinked to original sources

bioRxiv2025

Parental immune priming reshapes offspring growth, metabolism, and thermal tolerance in the Pacific Oyster

Pacific Oysters (Magallana/Crassostrea gigas) are marine bivalves that are widely cultivated but increasingly experience summer mortality due to interacting stressors. Two major concerns are (1) the rising severity and frequency of marine heat waves and (2) disease outbreaks (e.g., OsHV-1). It is critical to understand how these interacting stressors influence oyster resilience and how stress memory is passed down from parent to offspring. Specifically, it is not known how parental immune stress impacts offspring tolerance to other stressors, including heat stress. Therefore, we tested the effects of parental immune challenge on offspring performance under elevated temperature. Broodstock were exposed to a Poly(I:C) immune challenge, then their offspring were reared to the seed stage and assessed for survival, growth, and metabolic responses under thermal stress in the lab. We found that parental immune priming elicited metabolic flexibility in offspring, which may underlie altered stress tolerance. Offspring of immune-challenged parents were 6.5% larger by 236 days post-fertilization at the end of the study. Under elevated temperatures, offspring from treated parents had 35% lower mortality than controls at 40{degrees}C, but this was reversed at 42{degrees}C with 17% higher mortality compared to controls, suggesting thermal limits to priming benefits. Metabolic assays further revealed that at moderately elevated temperature (36{degrees}C), primed offspring had 43% higher metabolic activity, whereas at higher temperature (40{degrees}C), they exhibited 30% lower metabolic activity than controls. Offspring of immune primed parents differentially expressed heat shock (HSP70, HSP90) and immune genes (viperin) under acute stress, suggesting molecular mechanisms underlying immune priming effects. This pattern indicates that parental immune challenge may influence offspring metabolic flexibility, potentially enhancing thermal tolerance through an increased capacity for metabolic depression at extreme temperatures. Together, the results of this study highlight cross-generational links between immune priming and thermal tolerance.

physiology↗

bioRxiv2025

From Blue to Pink: Resazurin as a High-Throughput Proxy for Metabolic Rate in Oysters

Metabolic rate assays are critical tools for assessing organismal stress and resilience, yet their widespread application in aquaculture and ecological monitoring is limited. Improving these assays is essential for hatchery managers, farmers, and scientists seeking to identify resilient stocks and monitor stress in shellfish populations. Resazurin, a redox-sensitive dye commonly used in cell viability assays, offers a promising, high-throughput assay for metabolic rate assessment, but its application at the whole-organism level remains under explored. This study evaluates the efficacy of a resazurin-based metabolic assay in oysters (Crassostrea gigas and Crassostrea virginica) through four experimental approaches: (1) adaptation of the resazurin assay to measure oyster metabolism, (2) examination of temperature effects on oyster metabolism, (3) characterization of acute thermal stress responses, (4) examination of genetic variability in metabolism, and (5) correlations between metabolism and predicted performance in a selective breeding case study. Our findings confirm that resazurin fluorescence is correlated with oxygen consumption, validating its use as a measure of metabolism. Thermal performance assays reveal expected metabolic responses to temperature, including identification of optima and tipping points where metabolic stimulation shifts to depression under temperature stress. Acute thermal stress experiments demonstrate that oysters exhibiting greater metabolic depression are more likely to survive, supporting metabolism as a predictor of mortality. Further, genetic variation in stress responses is detected as family-level variation in metabolism. Metabolism of 50 families (C. virginica) selectively bred for performance in varying environments was measured and significantly correlated with predicted performance. By establishing resazurin as an additional reliable and scalable method for metabolic assessment, this study lays the groundwork for its broader adoption in aquaculture and conservation. Implementing this approach may provide a tool to enhance stock selection, improve hatchery management practices, and support adaptive strategies in the face of climate variability and increased environmental stress in coastal oceans.

physiology↗

bioRxiv2022

Sights and sounds of dolphins, Tursiops truncatus, preying on native fish of San Diego Bay and offshore in the Pacific Ocean

For the first time, dolphins wearing video cameras were observed capturing and eating live native fish. While freely swimming in San Diego Bay, one dolphin caught 69 resident fish, 64 demersal, 5 near surface, while the other caught 40, 36 demersal and 4 near the surface. Two other dolphins were observed capturing 135 live native fish in a sea water pool. Two additional dolphins were observed feeding opportunistically during open water sessions in the Pacific Ocean. Notably, one of these dolphins was observed to consume 8 yellow-bellied sea snakes (Hydrophis platurus). Searching dolphins clicked at intervals of 20 to 50 ms. On approaching prey, click intervals shorten into a terminal buzz and then a squeal. Squeals were bursts of clicks that varied in duration, peak frequency, and amplitude. Squeals continued as the dolphin seized, manipulated and swallowed the prey. If fish escaped, the dolphin continued the chase and sonar clicks were heard less often than the continuous terminal buzz and squeal. During captures, the dolphins lips flared to reveal nearly all of the teeth. The throat expanded outward. Fish continued escape swimming even as they entered the dolphins mouth, yet the dolphin appeared to suck the fish right down.

animal behavior and cognition↗

bioRxiv2020

Population genomics of louping ill virus provide new insights into the evolution of tick-borne flaviviruses

BackgroundThe emergence and spread of tick-borne arboviruses pose an increased challenge to human and animal health. In Europe this is demonstrated by the increasingly wide distribution of tick-borne encephalitis virus (TBEV, Flavivirus, Flaviviridae), which has recently been found in the UK. However, much less is known about other tick-borne flaviviruses (TBFV), such as the closely related louping ill virus (LIV), an animal pathogen which is endemic to the UK and Ireland but which has been detected in other parts of Europe including Scandinavia and Russia. The emergence and potential spatial overlap of these viruses necessitates improved understanding of LIV genomic diversity, geographic spread and evolutionary history. Methodology/principal findingsWe sequenced a virus archive composed of 22 LIV isolates which had been sampled throughout the UK over a period of over 80 years. Combining this dataset with published virus sequences, we detected no sign of recombination and found low diversity and limited evidence for positive selection in the LIV genome. Phylogenetic analysis provided evidence of geographic clustering as well as long-distance movement, including movement events that appear recent. However, despite genomic data and an 80-year time span, we found that the data contained insufficient temporal signal to reliably estimate a molecular clock rate for LIV. Additional analyses revealed that this also applied to TBEV, albeit to a lesser extent, pointing to a general problem with phylogenetic dating for TBFV. Conclusions/significanceThe 22 LIV genomes generated during this study provide a more reliable LIV phylogeny, improving our knowledge of the evolution of tick-borne flaviviruses. Our inability to estimate a molecular clock rate for both LIV and TBEV suggests that temporal calibration of tick-borne flavivirus evolution should be interpreted with caution and highlight a unique aspect of these viruses which may be explained by their reliance on tick vectors. Author SummaryTick-borne pathogens represent a major emerging threat to public health and in recent years have been expanding into new areas. LIV is a neglected virus endemic to the UK and Ireland (though it has been detected in Scandinavia and Russia) which is closely related to the major human pathogen TBEV, but predominantly causes disease in sheep and grouse. The recent detection of TBEV in the UK, which has also emerged elsewhere in Europe, requires more detailed understanding of the spread and sequence diversity of LIV. This could be important for diagnosis and vaccination, but also to improve our understanding of the evolution and emergence of these tick-borne viruses. Here we describe the sequencing of 22 LIV isolates which have been sampled from several host species across the past century. We have utilised this dataset to investigate the evolutionary pressures that LIV is subjected to and have explored the evolution of LIV using phylogenetic analysis. Crucially we were unable to estimate a reliable molecular clock rate for LIV and found that this problem also extends to a larger phylogeny of TBEV sequences. This work highlights a previously unknown caveat of tick-borne flavivirus evolutionary analysis which may be important for understanding the evolution of these important pathogens.

evolutionary biology↗

bioRxiv2020

Nanoscale pattern extraction from relative positions of sparse 3D localisations

We present a method for extracting high-resolution ordered features from localisation microscopy data by analysis of relative molecular positions in 2D or 3D. This approach allows pattern recognition at sub-1% protein detection efficiencies, in large and heterogeneous samples, and in 2D and 3D datasets. We used this method to infer ultrastructure of the nuclear pore, the cardiomyocyte Z-disk, DNA origami structures and the centriole.

cell biology↗

bioRxiv2018

Spindly is Required for Rapid Migration of Human Cells.

Dynein is the sole minus-end directed microtubule motor found in animals. It has roles in cell division, membrane trafficking, and cell migration. Together with dynactin, dynein regulates centrosomal orientation to establish and maintain cell polarity, controls focal adhesion turnover and anchors microtubules at the leading edge. In higher eukaryotes, dynein/dynactin requires additional components such as Bicaudal D to form an active motor complex and for regulating its cellular localization. Spindly is a protein that targets dynein/dynactin to kinetochores in mitosis and can activate its motility in vitro. However, no role for Spindly in interphase dynein/dynactin function has been found. We show that Spindly binds to the cell cortex and microtubule tips and colocalizes with dynein/dynactin at the leading edge of migrating U2OS cells and primary fibroblasts. U2OS cells that lack Spindly migrated slower in 2D than control cells, although centrosome polarization appeared to happen properly in the absence of Spindly. Re-expression of Spindly rescues migration, but the expression of a mutant, which is defective for dynactin binding, failed to rescue this defect. Taken together, these data demonstrate that Spindly plays an important role in mediating a subset of dynein/dynactins function in cell migration.

cell biology↗