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Horizontal gene transfer? Sea slug incorporates algae’s chlorophyll factories

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In “Sea slug surprise: It’s half-plant, half-animal” (MSNBC.com, January 12, 2012), Clara Moskowitz reports on a classic example of horizontal gene transfer:

Note: This observation has been questioned in recent research, which found that two of four species were only using the chloroplasts for food. [But two were using them then?]

“This is the first time that multicellar animals have been able to produce chlorophyll,” Pierce told LiveScience.

The sea slugs live in salt marshes in New England and Canada. In addition to burglarizing the genes needed to make the green pigment chlorophyll, the slugs also steal tiny cell parts called chloroplasts, which they use to conduct photosynthesis. The chloroplasts use the chlorophyl to convert sunlight into energy, just as plants do, eliminating the need to eat food to gain energy.

“We collect them and we keep them in aquaria for months,” Pierce said. “As long as we shine a light on them for 12 hours a day, they can survive [without food].”

The offspring seem to inherit the genes for producing chlorophyll, but not the chloroplasts:

The babies of thieving slugs retain the ability to produce their own chlorophyll, though they can’t carry out photosynthesis until they’ve eaten enough algae to steal the necessary chloroplasts, which they can’t yet produce on their own.

Just how the slugs make the genetics work remains unclear.

5 Replies to “Horizontal gene transfer? Sea slug incorporates algae’s chlorophyll factories

  1. 1
    DrREC says:

    Interesting observation that strongly supports endosymbiont theory and proposed gene transfer therein.

    Waiting for someone to call it “Non-darwinian” in the litany of things a scientist operating contemporaneous with legal slavery in the us couldn’t have possible foreseen.

  2. 2
    News says:

    Waiting? Why, DrREC? Didn’t you just sort of say it yourself?

    Endosymbiont … hmmm. Maybe that’s a better way of thinking about the capture of the chloroplasts. The photosynthesis stuff might be HGT, no?

    Interestingly, both Margulis (endosymbionts) and McClintock (HGT) are listed by Shapiro as non-Darwinian biologists.

  3. 3
    Petrushka says:

    Short wait.

  4. 4
    DrREC says:


    And a puzzling reply.

    “Endosymbiont … hmmm. Maybe that’s a better way of thinking about the capture of the chloroplasts”

    I’ve never heard of it referred to as anything but endosymbiont theory in the last few decades.

    “both Margulis (endosymbionts) and McClintock (HGT)”

    McClintock’s research was in transposons-“jumping genes.” To my knowledge, she never published on horizontal gene transfer.

    For that matter, I don’t really give a damn how you use what Shapiro calls “non-darwinian” as some sort of support by default for ID. It is silly semantics. Genes are non-darwinian in a historical sense.

  5. 5
    News says:

    Thanks for clariff re McClintock: here’s Shapiro:


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