Biology subjects

Rudd, D.

Publications and source records attributed to Rudd, D..

4 recordsLinked to original sources

bioRxiv2024

Friend, food, or foe: sea anemones discharge fewer nematocysts at familiar anemonefish after delayed mucus adaptation.

1.For decades, it has been hypothesized that anemonefishes are able to live within the stinging tentacles of host sea anemone species because the chemical composition of their mucus layer inhibits or lacks the trigger for firing host nematocysts. However, there is very little molecular evidence for this, beyond suggestions that glycans in the mucus could be key. In this study we assessed these hypotheses by testing Bubble-tip anemone (Entacmaea quadricolor) nematocysts in response to three different mucus sources, before and after anemonefish association. We also profiled the corresponding mucus lipid and glycan composition of anemonefish. Host sea anemones significantly reduced nematocyst firing at acclimated anemonefish mucus compared to mucus from unacclimated individuals. Changes in anemonefish mucus glycan composition became distinguishable three weeks after introduction relative to an anemonefish that was not living in association of a host sea anemone. The glycan composition reverted back to a pre-acclimated composition when profiled 24 hours after anemonefish removal from a host sea anemone. Triggering fewer nematocysts through glycan profile alterations may be an important adaptation that has enabled anemonefish to live long-term in a sea anemone host. However, the delay in mucus response indicates it is not the initial mechanism used by anemonefish to enter a host sea anemone without being stung.

ecology↗

bioRxiv2023

Nanodelivery of lipids to coral larvae maximises post-settlement survival: Implications for larval ecology and reef restoration.

Interest in reef restoration is increasing as coral mortality has accelerated at an unprecedented rate. However, high mortality rates of coral early-life stages represent a population bottleneck, which directly impacts the effectiveness of restoration projects. While most coral larvae are considered lecithotrophic and catabolise maternally transmitted lipids to meet metabolic demands; here we demonstrate that coral larvae can be facultative feeders. We used nanoparticles to deliver triacylglycerides to aposymbiotic larvae which resulted in a 30% increase in larval energetic lipids, and a 46% increase in survival rate, up to 16 weeks post-settlement. Changes in phospholipid molecular species in the larvae suggest phagocytosis of the nanoparticles, and an increase in free fatty acids indicates lipolysis of the phagocytosed triacylglycerides. We suggest that a continuum of nutritional strategies should be recognised in coral early-life stages, and that nanoparticles can be used by restoration practitioners to deliver nutritional resources to maximise restoration outcomes.

ecology↗

bioRxiv2023

Heat-evolved algal symbionts enhance bleaching tolerance of adult corals without trade-off against growth

Ocean warming has caused coral mass bleaching and mortality worldwide and the persistence of symbiotic reef-building corals requires rapid acclimation or adaptation. Experimental evolution of the corals microalgal symbionts followed by their introduction into coral is one potential method to enhance coral thermotolerance. Heat-evolved microalgal symbionts of the generalist species, Cladocopium proliferum (strain SS8), were exposed to elevated temperature (31{degrees}C) for [~]10 years, and were introduced into chemically bleached adult fragments of the scleractinian coral, Galaxea fascicularis. The new symbionts persisted for the five months of the experiment and enhanced adult coral thermotolerance compared with corals that were inoculated with the wild-type C. proliferum strain. Thermotolerance of SS8-corals was similar to that of coral fragments from the same colony hosting the homologous symbiont, Durusdinium sp., which is naturally heat-tolerant. However, SS8-coral fragments exhibited faster growth and recovered cell density and photochemical efficiency more quickly following chemical bleaching and inoculation under ambient temperature relative to Durusdinium-corals. Mass spectrometry imaging suggests that algal pigments involved in photobiology and oxidative stress were the greatest contributors to the thermotolerance differences between coral hosting heat-evolved versus wild-type C. proliferum. These pigments may have increased photoprotection in the heat-evolved symbionts. Our findings show that adult coral thermotolerance can be enhanced via the uptake of exogenously supplied, heat-evolved symbionts, without a trade-off against growth under ambient temperature. Heat-evolved C. proliferum remains in the corals in moderate abundance two years after its first inoculation, suggesting long-term stability of this novel symbiosis.

microbiology↗

bioRxiv2022

Spatial metabolomics for symbiotic marine invertebrates

Microbial symbionts frequently localize within specific body structures or cell types of their multicellular hosts. This spatiotemporal niche is critical to host health, nutrient exchange and fitness. Measuring host-microbe metabolite exchange has conventionally relied on tissue homogenates, eliminating dimensionality and dampening analytical sensitivity. We have developed a mass spectrometry imaging (MSI) workflow for a soft- and hard-bodied cnidarian animal capable of revealing the host and symbiont metabolome in situ, without the need for a priori isotopic labelling or skeleton decalcification. The MSI method provides critical functional insights that cannot be gleaned from bulk tissue analyses or other presently available spatial methods. We show that cnidarian hosts may regulate microalgal symbionts acquisition and rejection through specific ceramides distributed throughout the tissue lining the gastrovascular cavity; once resident, symbionts reside in light-exposed tentacles to generate photosynthate. These spatial patterns reveal how symbiont identity can drive host metabolism.

microbiology↗