Biology subjects

Johnson, L. E.

Publications and source records attributed to Johnson, L. E..

4 recordsLinked to original sources

bioRxiv2024

A blueprint for national assessments of the blue carbon capacity of kelp forests applied to Canadas coastline

Kelp forests offer substantial carbon fixation, with the potential to contribute to natural climate solutions (NCS). However, to be included in national NCS inventories, governments must first quantify the kelp-derived carbon stocks and fluxes leading to carbon sequestration. Here, we present a blueprint for assessing the national carbon sequestration capacity of kelp forests in which data synthesis and Bayesian hierarchical modelling enable estimates of kelp forest carbon production, storage, and export capacity from limited data. Applying this blueprint to Canadas extensive coastline, we find kelp forests store an estimated 1.4 Tg C in short-term biomass and produce 3.1 Tg C yr-1 with modest carbon fluxes to the deep ocean. Arctic kelps had the highest carbon stocks and production capacity, while Pacific kelps had greater carbon fluxes overall due to their higher productivity and export rates. Our transparent, reproducible blueprint represents an important step towards accurate carbon accounting for kelp forests.

ecology↗

bioRxiv2023

Life stage and vaccination shape the gut microbiome of hatchery-reared Atlantic salmon (Salmo salar)

Microbiomes play an essential role in promoting host health and fitness, but the factors affecting variation in gut microbiomes among individuals are not fully understood. Investigating the microbiome under different conditions is needed to link gut microbiomes to host physiology and potentially design manipulations to improve rearing success of captive species. In this study, we characterized the gut microbiomes of Atlantic salmon (Salmo salar) in individuals at different life stages, vaccination status, and hatchery origin. Microbiomes differed between age-0 sub-adults and adults, with sub-adults exhibiting higher diversity and more similar communities when compared to adults. We also found that vaccines against bacterial kidney disease reduced gut microbial diversity within individual sub-adult salmon, resulting in dissimilar gut microbial communities among individuals. The diversity and structure of microbiomes did not differ between groups of adults that were reared in two different hatcheries and sampled from the wild. Sub-adults, particularly unvaccinated sub-adults, displayed a strong core microbiome present in the majority of individuals. Our results suggest that life stage and vaccination status are essential factors in the gut microbiome development of salmon. Conditions experienced during early life stages appear to have a strong influence on the microbiome, but differences among individuals at early life stages may be lost due to environmental factors experienced later in life. The plasticity of the microbiome throughout the life of individuals may have important implications for understanding host health, with potential applications for improving the rearing and reintroduction success of the ecologically and economically important Atlantic salmon. IMPORTANCEThe Atlantic salmon (Salmo salar) is a globally important fisheries and aquaculture species, but the factors affecting gut microbiomes of hatchery-reared fish are not fully understood. Our study explores the influence of life stage, vaccination status, and hatchery origin on the composition and structure of the Atlantic salmon gut microbiome. We found that life stage is an important driver of gut microbiome diversity, likely driven by differences in habitat and diet. Vaccination against bacterial kidney disease led to marked declines in gut microbial diversity within individuals, resulting in highly distinct gut microbial communities among individuals. Hatchery origin did not have a strong influence on adult Atlantic salmon captured from the wild. These findings suggest that life stage and vaccination drive variation in Atlantic salmon microbiomes, but the stability and long-term implications of such variation on host health should be considered in future microbiome research.

microbiology↗

bioRxiv2021

Impaired lamin localization to the nuclear envelope is responsible for nuclear damage in LMNA mutant iPSC-derived cardiomyocytes

The LMNA gene encodes the nuclear envelope proteins Lamins A and C, which comprise a major part of the nuclear lamina, provide mechanical support to the nucleus, and participate in diverse intracellular signaling. LMNA mutations give rise to a collection of diseases called laminopathies, including dilated cardiomyopathy (LMNA-DCM) and muscular dystrophies. Although nuclear deformities are a hallmark of LMNA-DCM, the role of nuclear abnormalities in the pathogenesis of LMNA-DCM remains incompletely understood. Using induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) from LMNA mutant patients and healthy controls, we show that LMNA mutant iPSC-CM nuclei have altered shape or increased size compared to healthy control iPSC-CM nuclei. The LMNA mutation exhibiting the most severe nuclear deformities, R249Q, additionally caused reduced nuclear stiffness and increased nuclear fragility. Importantly, for all cell lines, the degree of nuclear abnormalities corresponded to the degree of Lamin A/C and Lamin B1 mislocalization from the nuclear envelope. The mislocalization was likely due to altered assembly of Lamin A/C. Collectively, these results point to the importance of correct lamin assembly at the nuclear envelope in providing mechanical stability to the nucleus and suggest that defects in nuclear lamina organization may contribute to the nuclear and cellular dysfunction in LMNA-DCM.

cell biology↗

bioRxiv2020

Spatially explicit modelling of kelp-grazer interactions: a seascape approach for effective habitat enhancement using artificial reefs.

O_LIArtificial structures are sprawling along the coast affecting the aspect and the functioning of shallow coastal seascapes. For years, the ecology of artificial structures has been investigated mainly in contrast to natural coastal habitats. However, it is increasingly emerging that structuring processes, such as trophic interactions, can depend on properties of the surrounding landscape. Heterogeneity of coastal seafloor and habitats could thus play a major role in determining the variability of ecological outcomes on artificial structures. Artificial reefs are being used in coastal areas in attempts to restore and enhance marine habitats and communities, including large brown seaweed ("kelp"), to offset habitat loss and mitigate coastal development impacts. The outcome of enhancement projects using artificial reefs have not always been either consistent or positive. Overlooking the effect of strong ecological interactions adds a high level of uncertainty and can undermine the success of these efforts. In Eastern Canada, top-down control exerted by green sea urchins (Strongylocentrotus droebachiensis) can seriously compromise the success of artificial reefs for kelp enhancement. Importantly, urchin interactions with macroalgae are likely to be influenced by the bottom composition. A seascape approach could thus integrate behavior and habitat heterogeneity. C_LIO_LIWe investigated whether the local seascape could create zones of differential grazing risk for kelp outplanting kelp (Alaria esculenta) on artificial blocks on an heterogenous bottom. Adopting a spatially explicit framework, we determined how seascape affected the urchin use of the habitat and used this information to map the grazing risk throughout the area. C_LIO_LIKelp survival was a function of frequency of urchin presence throughout the study site. While urchins avoided sandy patches, bottom composition and algal cover modulated the within-patch urchin use of the habitat. This translated in the heterogeneity of grazing risk intensity. C_LIO_LISynthesis and applications. The presence of discrete seascape features locally increased the grazing risk for kelp by differentially affecting the urchins usage of the habitat, even within the same bottom patch. Incorporating this information when planning artificial reefs could minimize the detrimental grazing risk thus increasing the rate of success and ensuring lasting results. C_LI

ecology↗