A group of scientists in Princeton's Department of Ecology and Evolutionary Biology has uncovered a new biological mechanism that could provide a clearer window into a cell's inner workings.
What's more, this mechanism could represent an "epigenetic" pathway -- a route that bypasses an organism's normal DNA genetic program -- for so-called Lamarckian evolution, enabling an organism to pass on to its offspring characteristics acquired during its lifetime to improve their chances for survival. Lamarckian evolution is the notion, for example, that the giraffe's long neck evolved by its continually stretching higher and higher in order to munch on the more plentiful top tree leaves and gain a better shot at surviving.
The research also could have implications as a new method for controlling cellular processes, such as the splicing order of DNA segments, and increasing the understanding of natural cellular regulatory processes, such as which segments of DNA are retained versus lost during development. The team's findings will be published Jan. 10 in the journal Nature.
Princeton biologists Laura Landweber, Mariusz Nowacki and Vikram Vijayan, together with other members of the lab, wanted to decipher how the cell accomplished this feat, which required reorganizing its genome without resorting to its original genetic program. They chose the singled-celled ciliate Oxytricha trifallax as their testbed.
Ciliates are pond-dwelling protozoa that are ideal model systems for studying epigenetic phenomena. While typical human cells each have one nucleus, serving as the control center for the cell, these ciliate cells have two. One, the somatic nucleus, contains the DNA needed to carry out all the non-reproductive functions of the cell, such as metabolism. The second, the germline nucleus, like humans' sperm and egg, is home to the DNA needed for sexual reproduction.
When two of these ciliate cells mate, the somatic nucleus g
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