Saturday, April 14, 2007

From E. Coli to Chestnut Tigers

This saturday morning, I chatted with Dr. Ueda of Riken about his research on biological clockes, in the editorial office of Nikkei Science. While we strolled in the corridor of interesting facts and ponderings, he mentioned a ongoing research in which the investigator cultured E. Coli for 20 years. Apparently these small chaps "adapted" to the new environment. Wild types of E. Coli, when put into a new environment, do not start dividing until after some delay period, consistent with the idea that the primitive biological forms are "probing" the environment to see if it is fit. The cultured E. Coli, on the other hand, somehow learn to start reproduction "straight away". Presumably they have figured out that the environment they are in is fit for proliferating, and no initial probings are necessary. The underlying molecular mechanisms behind this adaptation are still to be elucidated.

That story somehow reminded me of the butterfly Chestnut Tiger (Parantica sita). This is a beautiful but poisonous species. The birds, after learning that these creatures with inviting appearances actually taste nastily, do not bother them. Chestnut Tigers therefore fly very slowly, with a certain air of elegance, as if they know they wouldn't be chased by birds. When an ignorant enemy tries to attack them, however, for example by the small boy that was I thiry-something years ago, Chestnut Tigers would suddenly shoot up into the high air.

When, however, I waved my hands towards the artificicially cultivated Chestnut Tigers in the Giant Glass Insect Dome of Tama zoo, they could be hardly less perturbated. They have somehow learned that they were now enclosed in a space with a ceiling, and that shooting up into the air did not make any sense. They just kept flying in a slow-motion elegance, after some irritated movement induced by my hands.

The adaptabilities of biological systems, from E. Coli to Chestnut Tigers, never ceases to amaze me. The wonder is how the system and molecules work together to make it happen.

1 comment:

susie said...


I wonder if Chestnut Tigers' acquired knowledge that they have a ceiling above them is inherited to the next generation.