Monday, January 3, 2011

What is Life? Evolution from invertebrates to vertebrates 6(無脊椎動物から脊椎動物への進化その6)

Good morning everyone. Did you receive many greeting cards from your old friends or teachers? It is annual greeting to show your acknowledgements and respectfulness. I don't think that such cards are just a custom to keep relation to others.


Anyway, let me start "What is Life?" now. This is the 6th class to show a hypothesis about the mechanism of the evolution from invertebrates to vertebrates. The climax will come soon.

さて、What is Life?を始めましょう。今回で6回目となります。無脊椎動物から脊椎動物への進化はどのようにして起こったのでしょうか。クライマックスは近づいてきております。

We had been struggled to identify the factors for the metamorphosis of feeding sea urchin larvae, although we had a clue. The factors must be contained in the food. But, by the suggestion of a assistant professor for trying thyroid hormones for experiments brought out dramatical story.


As you may know, thyroid hormones promote the metamorphosis of frog, and control various metabolism in vertebrates. It is one of the most important hormones for us. From the suggestion, the sea urchin larvae were exposed thyroid hormones with various concentration at the point. The hormones showed surprisingly effects against the larvae. 


The adults rudiments were highly promoted than the control, and the larval bodies were dramatically shrunk as well in dose dependent manner. We also checked the intensity of T3 and T4 for the larval effects. Surprisingly, the effects of T4 were 10-fold strong rather than T3 in sea urchin larvae. We had not elucidated the difference between vertebrates to echinoderm, but it must be related with the history of evolution.


With some supplement data, we published such hormones effects for the metamorphosis of feeding sea urchin larvae. This cover photo of the journal published with the article was taken by Sammy, it is additional information(^^;).

By the way, there was a tough problem suggested by a referee. The problem was the origin of the hormone. Endogenous or Exogenous. If the hormones were synthesized in the larval body, the hormones were identified as real endogenous factors. It is called as "hormone". So we tried to the next step shown in the next class.


Today's class is over. Have a nice day. Click the button at the bottom of this "What is Life?", if you are a student of this class. Mind you? If you have any question about life, please send an e-mail for me.


にほんブログ村 科学ブログ 生物学・生物科学へ人気ブログランキングへ



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