July 4th, 2006



Обычно мы неявно исходим из положения, что конкретному генотипу соответствует определенный фенотип. Однако в природе достаточно распространен иной характер взаимосвязи: один генотип - два (или более) фенотипа. Фактически, в нуклеотидной последовательности "скрыты" сразу несколько вариантов организма, каждый из которых может реализоваться в зависимости от внешних условий или истории индивидуального развития...Для таких случаев существует понятие "дискретных адаптивных норм".

Успехи совр. биологии (2002)
Адаптации особи и клона: механизмы и роли в эволюции (PDF)

Новое окно в эпигенетику


Rewired brain' revives patient after 19 years

In 1984, 19-year-old Terry Wallis was thrown from his pick-up truck during an accident near his home in Massachusetts, US. He was found 24 hours later in a coma with massive brain injuries.
Within a few weeks he had stabilised in a minimally conscious state, which his doctors thought would last indefinitely. It did indeed persist for 19 years. Then, in 2003, he started to speak.
Over a three day period, Wallis regained the ability to move and communicate, and started getting to know his now 20 year old daughter - a difficult process considering he believed himself to be 19, and that Ronald Reagan was still president.

The team's findings suggest that Wallis’s brain had, very gradually, developed new pathways and completely novel anatomical structures to re-establish functional connections, compensating for the brain pathways lost in the accident.
They found that new axons - the branches that connect neurons together - seemed to have grown, establishing novel working brain circuits.
Surprisingly, the circuits look nothing like normal brain anatomy. A lot of the damage had been to axons that passed from one side of the brain to the other, torn by the force of the accident. But Schiff says that new connections seem to have grown across around the back of the brain, forming structures that do not exist in normal brains.

New Scientist, July 2006
Nature News

The Journal of Clinical Investigation, July 2006
Tracking the recovery of consciousness from coma (Commentary)
Possible axonal regrowth in late recovery from the minimally conscious state (Research Article)

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см. также http://nature-wonder.livejournal.com/73224.html