Host animals in algal-invertebrate endosymbiotic associations are exposed to photosynthetically generated hyperoxia while in sunlight, conditions conducive to photodynamic excitations and production of cytotoxic oxygen-derived radicals such as the superoxide anion (O2−) and the hydroxyl radical (OH). All previous vidence of oxyradical production in symbiotic associations has been circumstantial. We here present direct evidence, from electron paramagnetic resonance studies on tissue homogenates of the photosymbiont-containing sea anemone Anthopleura elegantissima (Brandt), of substantial light-dependent OH and O2 production that is abolished by dichlorophenyldimethylurea (DCMU), an inhibitor of photosynthesis. Shade-adapted A. elegantissima lacking endosymbiotic algae likewise show OH production upon illumination. The latter flux is not dependent on photosynthesis, and DCMU has no effect. Rather, OH production in apozooxanthellate anemones is via direct photoexcitations. The selective reaction of dimethyl sulfoxide (DMSO) with OH to form methane sulfinic acid allows quantification of OH produced in vivo. Such in vivo measurements confirm the production of OH in both host and algae in illuminated zooxanthellate anemones, where the amount of OH in the zooxanthellae is disproportionately large relative to their fractional contribution to the biomass of the symbiosis. In vivo studies using DMSO also suggest a photochemical production of OH in apozooxanthellate anemones exposed to simulated sunlight enriched in ultraviolet (UV) wavelengths, and the enhancement by UV light of OH production in zooxanthellate individuals. Such chronic radical exposure necessitates defenses
In the field: an interview with Harald Wolf
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In our new Conversation, Harald Wolf talks about his fieldwork experiences working with desert ants in Tunisia to understand their navigation.
Propose a new Workshop
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Our Workshops bring together leading experts and early-career researchers from a range of scientific backgrounds. Applications are now open to propose Workshops for 2024, one of which will be held in a Global South country.
Julian Dow steps down and John Terblanche joins the JEB team
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After 15 years with the journal, Julian Dow from University of Glasgow, UK, is stepping down as a Monitoring Editor. We wish Julian all the best for the future and welcome John Terblanche, Stellenbosch University, South Africa, who is joining the team. Julian talks about his long association with The Company of Biologists and the journal and John tells us about his life and career in this News article.
Ecotourism affecting iguana glucose tolerance
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Ecotourists feeding grapes on skewers to north Bahamian rock iguanas may be doing the reptiles more harm than good as the sugar charged diet is giving the animals high blood sugar.
Evolution of metabolic plasticity
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In their Commentary, Frank Seebacher and Julian Beaman propose that metabolic plasticity originated in prebiotic protocells and that it was a pre-requisite for effective transfer of genetic material across generations – the hallmark of Darwinian evolution.
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