Biology subjects

Ross, A. N.

Publications and source records attributed to Ross, A. N..

4 recordsLinked to original sources

bioRxiv2026

Flight crashes have demographic consequences in a long-lived seabird

Risk is a key currency in animal ecology, yet studies of risk have almost exclusively focused on predation. Accidents, defined as a momentary loss of control, represent another potential source of injury and mortality. Such events are seldom documented and are generally assumed to be vanishingly rare in natural systems. Nonetheless, regular crash-based mortality has been documented in a population of northern gannets through monthly surveys conducted over three years in the 1970s. We revisit these data, using hindcasting, environmental records and computational fluid dynamics (CFD) models to investigate the environmental drivers of gannet crashes, and matrix population models to examine their demographic consequences under a range of environmental scenarios. Wind direction emerged as the sole predictor of crash-based mortality, with the probability of crashes increasing in north-westerly winds. CFD models revealed that north-westerlies are associated with a marked increase in turbulent kinetic energy along the breeding cliffs, relative to the other modal wind direction, which likely challenges flight control. A total of 367 crashes accounted for 5.4% of annual adult mortality. Removing this mortality led to a projected increase in population of 23.9% over 50 years, equivalent to an additional 10,583 individuals. Overall, this suggests that turbulence close to the substrate can result in fatal losses of flight control that can impact population-level processes. Our results also highlight the need for greater understanding of how airflows influence the risk of accidents across flying animals, both in current and changing wind regimes.

zoology↗

bioRxiv2025

Genetic compensation in podocalyxin-like mutants during zebrafish liver development

Hepatic stellate cells (HSCs) are critical for normal liver development and regeneration. Podocalyxin-like (podxl) is highly expressed in zebrafish HSCs, but its role in liver development is not known. Here we report that podxl knockdown using CRISPR/Cas9 (CRISPants) significantly decreased HSC number in zebrafish larvae at different time points and in two independent HSC reporter lines, supporting a role for podxl in HSC development. We generated five podxl mutants, including two mutants lacking the predicted podxl promoter region, and found that none of the mutants recapitulated the knockdown phenotype. Podxl CRISPR/Cas9 injection in mutants lacking the podxl guide RNA cut site did not affect HSC number, supporting the hypothesis that the CRISPant phenotype was specific, requiring intact podxl. Podxl mRNA levels in three podxl mutants were similar to those of wildtype controls. RNA sequencing of podxl mutants and controls showed no significant change in transcript levels of genes with sequence similarity to podxl, but it revealed upregulation of a network of extracellular matrix genes in podxl mutants. These results support a role for podxl in zebrafish liver development and suggest that upregulation of a group of functionally related genes represents the main mechanism of compensation for podxl genomic loss.

developmental biology↗

bioRxiv2023

Phospholipid isotope tracing reveals β-catenin-driven suppression of phosphatidylcholine metabolism in hepatocellular carcinoma

Background and AimsActivating mutations in the CTNNB1 gene encoding {beta}-catenin are among the most frequently observed oncogenic alterations in hepatocellular carcinoma (HCC). HCC with CTNNB1 mutations show profound alterations in lipid metabolism including increases in fatty acid oxidation and transformation of the phospholipidome, but it is unclear how these changes arise and whether they contribute to the oncogenic program in HCC. MethodsWe employed untargeted lipidomics and targeted isotope tracing to quantify phospholipid production fluxes in an inducible human liver cell line expressing mutant {beta}-catenin, as well as in transgenic zebrafish with activated {beta}-catenin-driven HCC. ResultsIn both models, activated {beta}-catenin expression was associated with large changes in the lipidome including conserved increases in acylcarnitines and ceramides and decreases in triglycerides. Lipid flux analysis in human cells revealed a large reduction in phosphatidylcholine (PC) production rates as assayed by choline tracer incorporation. We developed isotope tracing lipid flux analysis for zebrafish and observed similar reductions in phosphatidylcholine synthesis flux accomplished by sex-specific mechanisms. ConclusionsThe integration of isotope tracing with lipid abundances highlights specific lipid class transformations downstream of {beta}-catenin signaling in HCC and suggests future HCC-specific lipid metabolic targets. SynopsisIn this work, we show by lipid specific isotope tracing that mutations in the oncogene CTNNB1 leads to conserved changes in lipid metabolism in hepatocellular carcinoma. These include the stimulation of fatty acid oxidation and a suppression of phosphorylcholine synthesis.

cancer biology↗

bioRxiv2022

Pelagic seabirds reduce risk by flying into the eye of the storm

Cyclones can cause mass mortality of seabirds, sometimes wrecking thousands of individuals. The few studies to track pelagic seabirds during cyclones show they tend to circumnavigate the strongest winds. We tracked adult shearwaters in the Sea of Japan over 11 years and find that the response to cyclones varied according to the wind speed and direction. In strong winds, birds that were sandwiched between the storm and mainland Japan flew away from land and towards the eye of the storm, flying within [≤] 30 km of the eye and tracking it for up to 8 hours. This exposed shearwaters to some of the highest wind speeds near the eye wall ([≤] 21 m s-1), but enabled them to avoid strong onshore winds in the storms wake. Extreme winds may therefore become a threat when an inability to compensate for drift could lead to forced landings and collisions. Birds may need to know where land is in order to avoid it. This provides additional selective pressure for a map sense and could explain why juvenile shearwaters, which lack a map sense, instead navigating using a compass heading, are susceptible to being wrecked. We suggest that the ability to respond to storms is influenced by both flight and navigational capacities. This may become increasingly pertinent due to changes in extreme weather patterns. Significance StatementCyclones can cause billions of dollars of damage and loss of human life. They can also cause mass mortality and strandings in seabirds. We used GPS tracking data from streaked shearwaters breeding in the worlds most active cyclone basin to understand how seabirds respond to these systems. Birds varied their response according to the wind speed and direction, generally flying towards the eye of the cyclone in strong winds. This surprising strategy enables dynamic soaring birds to control their exposure to risky wind vectors that could drift them onshore. Nonetheless, birds may need to know where land is in order to avoid it. Juveniles lack this "map sense", making them susceptible to wrecking in some scenarios.

ecology↗