Daphnia: higher carotenoids when provided good light

[RobM]

Thanks Jen.

The article appears to prove that daphnia do retain more carotenoids under good lighting, and that the experiments results where not affected by increased photosynthesis. Although I still believe that increased photosynthesis (and therefore more carotenoid rich food) would be another benefit with providing daphnia good lighting.

Caleb, you may be interested to know that it appears the carotenoids are stored as free carotenoids in the fat globules. However it is stored as carotenoid-protein in eggs, which is broken down into free carotenoids around the time the embryos are released from the brood pouch.
(or this is my interpretation).

Also an important point to make is that this article points out that the deposition of carotenoids is reversible, taking affect after 4-5 days.
Caleb, mentioned that it is difficult to 'intentionally' excrete carotenoids for most organisms, although the article does not specify how, or the difficulties involved (or intentions) it does mention that daphnia are able to excrete carotenoids.

 

[caleb]

Another interesting point raised by the paper is that because Daphnia concentrate carotenoids/carotenoproteins in their eggs, females will have their highest carotenoid content just before they give birth (and their lowest, just after).

The paper doesn't really address just how much light makes a difference- the control group were in complete darkness. It would be interesting to know if there's such a marked difference between daylight and sunlight... or even darkness and sunlight.