on the hosting species, the algae are taken up by the devel- oping egg or embryo, ... from adult salamander tissues, including from parts of their reproductive ...
LIFE LINES LIFE LINES LIFE LINES
Going green with algae T
he Green Man – you may never have heard of him, But why bother to house whole algal though he has been around for centuries. You may never cells if you can get by with just their have noticed him, but you can find him easily enough carved chloroplasts? Indeed, kleptoplasty – basion the roof bosses and columns of medieval churches, abbeys, cally stealing the chloroplasts you need to become photosynand cathedrals across Europe. He decorates even older temples thetic – is an alternative practiced by certain dinoflagellates, in the Middle East. You may not know his significance, but ciliates, foraminifera, and even some metazoans: the then no one really does. What could a man’s face with leaves sacoglossan sea slugs. These latter animals feed on algae, but growing out of it (technically a “foliate head”), or with they do not digest the chloroplasts. Rather, these organelles branches issuing from his mouth or eyes, mean? An ancient are taken up whole by the epithelium of the slug’s extensivepagan symbol of rebirth and renewal? Of human reliance on ly branched gut, conferring not just a bright green camounature? Of fertility? Perhaps he is a spirit of nature, a demon, or flage to the entire animal, but the ability to truly photosynsome ancient god? Osiris, the Egyptian god of vegetation thesize. Some species can retain their stolen chloroplasts only (along with the Underworld), was usually painted with a green for a few days and need a constant supply of new ones, face; could it be him? Sadly, we seem to have forgotten. but others have found ways to preserve them for much Perhaps to different cultures he longer. The nudibranch Elysia meant different things. For me at chlorotica, for example, which least, the Green Man is a lives off the Atlantic coast of reminder of life’s inventiveness, North America, can maintain its for Nature has already found sevchloroplasts in a functional state eral solutions to the shocking, for some 14 months and, when seemingly impossible mix of plant fully loaded up, need not feed and animal his face conveys. heterotrophically at all. How We are accustomed to hearthis system works, however, ing that the corals of shallow, remains a mystery, for although tropical seas enter into symbiotchloroplasts carry their own ic relationships with algae (usuDNA, they require the assisally of the zooxanthellae), tance of algal nuclear genes for sometimes adopting strikingly photosynthesis to occur. So, green hues. The corals provide have these sea slugs incorporated urea (a source of nitrogen) and Green Men looking down from roof bosses in Norwich these genes into their own other nutrients to the algae and Cathedral (UK). genome? At least some research receive carbohydrates made by suggests they have not (Mol Biol photosynthesis in return. But they are not alone in this Evol 2011; 28: 699–706). Some animals might have even started down the road type of relationship. Representatives of the foraminifera, radiolaria, jellyfish, anemones, nudibranchs, and even toward developing their very own light-harvesting systems. some clams also maintain algal endosymbionts. Depending In 2010, it was reported that the Oriental hornet (Vespa on the hosting species, the algae are taken up by the devel- orientalis) may take advantage of the xanthopterin in its oping egg or embryo, or in older organisms via the ecto- yellow stripes to capture light energy (Naturwissenschaften derm or the cells lining the gut. Even amphibians are in on 2010; 97: 1067–76) and produce electricity, although just the act; algae are present in the jelly-like egg capsules of how the insect uses this product is unknown. Nonetheless, wood frogs (Lithobates sylvaticus) and the spotted salaman- it does appear to give them a buzz; these hornets are most der (Ambystoma maculatum), giving them a green tinge. active when the light is strongest. Perhaps, then, the Green Man is neither symbol nor spirit After receiving nitrogenous waste released by the embryos, the algae repay them with boosts of photosynthetic oxy- nor demon nor god, but an evolutionary prophecy that one gen. On 28 July 2010, however, at the Ninth International day animals will learn the trick of garnering energy from Congress of Vertebrate Morphology in Punta del Este, light. I wonder, however, whether he may also be a forecastUruguay, Ryan Kerney (now at Gettysburg College, PA) er of other things to come. In a recent paper (PloS ONE reported algae (Oophila amblystomatis) inside the cells of 2011; 6: e18877), Christina Agapakis et al. wrote: “Our embryonic spotted salamanders. “[And they] persist in the results show that it is possible to engineer photosynthetic adult”, he says. “We’ve amplified algal 18S ribosomal DNA bacteria to invade the cytoplasm of mammalian cells for furfrom adult salamander tissues, including from parts of their ther engineering and applications in synthetic biology”. Don’t say you were never warned! reproductive system. Our current hypothesis is that some Adrian Burton of these algal cells may be passed down from one genera( @AdrianBurton_) tion to the next.” © J Ward, Aston Rowant, Oxfordshire
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