Biology subjects

Peck, L. S.

Publications and source records attributed to Peck, L. S..

7 recordsLinked to original sources

bioRxiv2026

Antarctic fish cell cultures show adaptation of organelle morphology and dynamics to extreme cold

In the Antarctic Southern Ocean, cold-blooded animals have evolved to live at stable temperatures of 0{+/-}2 {degrees}C. This extremely low temperature affects their biology at every scale, from protein folding to development. However, how animal (sub)cellular organisation and dynamics are adapted to near-0 {degrees}C temperatures has not been studied. We therefore established methods to culture and fluorescently label cells from the Antarctic plunderfish Harpagifer antarcticus and a temperate comparator species, the shanny Lipophrys pholis. By imaging these cultures live at physiological temperatures, we found that subcellular organisation is broadly conserved in H. antarcticus, featuring known membranous organelles and biomolecular condensates that remain dynamic, with mitochondria in H. antarcticus and L. pholis moving at similar speeds. However, we also identified differences in organelle properties between H. antarcticus and L. pholis, including lysosomal enlargement and mitochondrial morphology changes. These differences may be functionally linked to protein misfolding and slow embryonic development in Antarctic species.

cell biology↗

bioRxiv2024

A high-resolution microscopy system for biological studies of cold-adapted species under physiological conditions

The fundamental processes governing life are sensitively dependent on temperature. Whilst much is known about the constraints on how proteins operate at 37{degrees}C, little knowledge exists about how biological function is maintained sub-zero temperature conditions, where proteins are less stable and oxidative damage is high. However, almost 90% of habitable environments on Earth are permanently below 5{degrees}C (i.e. the deep sea and polar regions). This means that we do not understand how a large and diverse proportion of the global biome functions. To address this question at the cellular level, tools are required for imaging biological systems at high resolution under physiological conditions. This poses severe technical challenges that cannot be addressed with traditional optical microscopy techniques. High-resolution imaging objectives require short working distances and the use of immersion media, which lead to rapid heat transfer from the microscope to the sample. This affects the viability of live specimens and the interpretability of the results when the sample function optimally at low temperatures. Condensation and temperature-induced shrinking of components pose further challenges, reducing image resolution and contrast. Here, we address these issues and provide a method for high-fidelity imaging of live biological samples at temperatures of around, or below, 0{degrees}C. Our method is compatible with different microscopy modalities, including super-resolution imaging. It relies on hardware additions to traditional microscopy systems that can be straightforwardly implemented, namely, a cooling collar, 10% ethanol as an immersion medium, and nitrogen flow to mitigate condensation. We demonstrate the method in live cell cultures derived from Antarctic fish species and highlight the need to maintain physiological conditions for these fragile biological samples. Future applications are diverse and include evolutionary biology and the study of cold-adapted organisms, as well as cellular biophysics and several applications in biotechnology.

biophysics↗

bioRxiv2022

Evolutionary conservation and divergence of the transcriptional regulation of bivalve shell secretion across life history stages

Adult molluscs produce shells with diverse morphologies and ornamentations, different colour patterns and microstructures. The larval shell however, is a phenotypically more conserved structure. How do developmental and evolutionary processes generate varying diversity at different life history stages? Using live-imaging, histology, scanning electron microscopy and transcriptomic profiling, we have described shell development in a heteroconchian bivalve the Antarctic clam, Laternula elliptica and compared it to adult shell secretion processes in the same species. Adult downstream shell genes, such as those encoding extracellular matrix proteins and biomineralisation enzymes, were largely not expressed during shell development, and instead, a development-specific downstream gene repertoire was expressed. Upstream regulatory genes such as transcription factors and signalling molecules were conserved between developmental and adult shell secretion. Comparing heteroconchian transcriptomic data with recently reported pteriomorphian larval shell proteome data suggests that, despite being phenotypically more conserved, the downstream effectors constituting the larval shell "tool-kit" may be as diverse as that of adults. Overall, our new data suggests that a larval shell formed using development-specific downstream effector genes is a conserved and ancestral feature of the bivalve lineage, and possibly more broadly across the molluscs.

evolutionary biology↗

bioRxiv2021

Latitudinal patterns in intertidal ecosystem structure in West Greenland suggest resilience to climate change

Climate change has ecosystem-wide cascading effects. Little is known, however, about the resilience of Arctic marine ecosystems to environmental change. Here we quantify and compare large-scale patterns in rocky intertidal biomass, coverage and zonation in six regions along a north-south gradient of temperature and ice conditions in West Greenland (60-72{degrees}N). We related the level and variation in assemblage composition, biomass and coverage to latitudinal-scale environmental drivers. Across all latitudes, the intertidal assemblage was dominated by a core of stress-tolerant foundation species that constituted >95% of the biomass. Hence, canopy-forming macroalgae, represented by Fucus distichus subsp. evanescens and F. vesiculosus and, up to 69 {degrees}N, also Ascophyllum nodosum, together with Semibalanus balanoides, occupied >70% of the vertical tidal range in all regions. Thus, a similar functional assemblage composition occurred across regions, and no latitudinal depression was observed. The most conspicuous difference in species composition from south to north was that three common species (the macroalgae Ascophyllum nodosum, the amphipod Gammarus setosus and the gastropod Littorina obtusata) disappeared from the mid-intertidal, although at different latitudes. There were no significant relationships between assemblage metrics and air temperature or sea ice coverage as obtained from weather stations and satellites, respectively. Although the mean biomass decreased >50% from south to north, local biomass in excess of 10 000 g ww m-2 was found even at the northernmost site, demonstrating the patchiness of this habitat and the effect of small-scale variation in environmental characteristics. Hence, using the latitudinal gradient in a space-for-time substitution, our results suggest that while climate modification may lead to an overall increase in the intertidal biomass in north Greenland, it is unlikely to drive dramatic functional changes in ecosystem structure in the near future. Our dataset provides an important baseline for future studies to verify these predictions for Greenlands intertidal zone.

ecology↗

bioRxiv2020

Global gradients in intertidal species richness and functional groups

Whether global latitudinal diversity gradients exist in rocky intertidal -diversity and across functional groups remains unknown. Using literature data from 433 intertidal sites, we investigated -diversity patterns across 155{degrees} of latitude, and whether local-scale or global-scale structuring processes control -diversity. We, furthermore, investigated how the relative composition of functional groups (algae, grazers, predators and suspension-feeders) changes with latitude. -diversity differed among hemispheres with a mid-latitudinal peak in the north, and a non-significant unimodal pattern in the south, but there was no support for a latitudinal diversity gradient. Although global-scale drivers had no discernible effect, the local-scale drivers significantly affected -diversity, and our results reveal that latitudinal diversity gradients are outweighed by local-processes. In three functional groups: predators, grazers and suspension-feeders diversity declined with latitude, coinciding with an inverse gradient in algae. Overall, we propose more studies are needed on the magnitude and influence of physical and biotic drivers across multiple scales.

ecology↗

bioRxiv2018

Plasticity and environmental heterogeneity predict geographic resilience patterns of foundation species to future change

Although geographic patterns of species sensitivity to global environmental changes are defined by interacting multiple stressors, little is known about the biological mechanisms shaping regional differences in organismal vulnerability. Here, we examine large-scale spatial variations in biomineralisation under heterogeneous environmental gradients of temperature, salinity and food availability across a 30{degrees} latitudinal range (3,334 km), to test whether plasticity in calcareous shell production and composition, from juveniles to large adults, mediates geographic patterns of resilience to climate change in critical foundation species, the mussels Mytilus edulis and M. trossulus. We find mussels produced thinner shells with a higher organic content in polar than temperature regions, indicating decreasing shell calcification towards high latitudes. Salinity was the major driver of regional differences in mussel shell deposition, and in shell mineral and organic composition. In low-salinity environments, the production of calcite and organic shell layers was increased, providing higher resistance against dissolution in more corrosive waters. Conversely, under higher-salinity regimes, increased aragonite deposition suggests enhanced mechanical protection from predators. Interacting strong effects of decreasing salinity and increasing food availability on the compositional shell plasticity in polar and subpolar mussels during growth predict the deposition of a thicker external organic layer (periostracum) under forecasted future environmental conditions. This marked response potential of Mytilus species suggests a capacity for increased protection of high-latitude mussel populations from ocean acidification. Our work illustrates that mechanisms driving plastic responses to the spatial structure of multiple stressors can define geographic patterns of unforeseen species resilience to global environmental change.

ecology↗

bioRxiv2018

Adaptation of proteins to the cold in Antarctic fish: A role for Methionine?

The evolution of antifreeze glycoproteins has enabled notothenioid fish to flourish in the freezing waters of the Southern Ocean. Whilst successful at the biodiversity level to life in the cold, paradoxically at the cellular level these stenothermal animals have problems producing, folding and degrading proteins at their ambient temperatures of down to -1.86{degrees}C. In this first multi-species transcriptome comparison of the amino acid composition of notothenioid proteins with temperate teleost proteins, we show that, unlike psychrophilic bacteria, Antarctic fish provide little evidence for the mass alteration of protein amino acid composition to enhance protein folding and reduce protein denaturation in the cold. The exception was the significant over-representation of positions where leucine in temperate fish proteins was replaced by methionine in the notothenioid orthologues. Although methionine may increase stability in critical proteins, we hypothesise that a more likely explanation for the extra methionines is that they have been preferentially assimilated into the genome because they act as redox sensors. This redox hypothesis is supported by the enrichment of duplicated genes within the notothenioid transcriptomes which centre around Mapk signalling, a major pathway in the cellular cascades associated with responses to environmental stress. Whilst notothenioid fish show cold-associated problems with protein homeostasis, they may have modified only a selected number of biochemical pathways to work efficiently below 0{degrees}C. Even a slight warming of the Southern Ocean might disrupt the critical functions of this handful of key pathways with considerable impacts for the functioning of this ecosystem in the future.

evolutionary biology↗