About 50 years ago researchers discovered that the quantity of purple color in corn deviated from the accepted laws of heredity. However, this paramutation, or a genetic trait that, according to theory, should have been removed over the generations but has resurfaced in newer generations, remained unexplained. In 2006 Minoo Rassoulzadegan of Inserm in France and some of his colleagues noticed a similar occurrence of paramutations when working with mutant mice. A mutation in the Kit gene causes white pathces of fur to grow in certain areas on brown-coated mice. Researchers bred two heterozygous parents, each with one normal copy of the gene and one mutated copy of it. The scientists hypothesized that the offspring that inherited 2 normal copies of the gene should not have developed the white patches on their coats, but they did. In searching for an explanation to this phenomena, researchers noticed that the mutant mice had unusually low levels of regular RNA and higher levels of mRNA (messenger RNA), and the mRNA was found to have made its way into the sperm. When testing this hypothesis by injecting this RNA into embryos 50% of the offspring had the white patches. Although we still don't know why the RNA is having an effect on hereditary factors, this discovery may force biology textbooks to rewrite the chapters on the causes for genetic variations.
This experiment was an example of hypothesis-based science because the scientists noticed certain patterns and then based on previous knowledge made a hypothesis which they tested various times in order to find an explanatory result for their question.
This experiment was an example of hypothesis-based science because the scientists noticed certain patterns and then based on previous knowledge made a hypothesis which they tested various times in order to find an explanatory result for their question.
Author: David Biello
Title of Article: Mouse Finding Violates Law of Heredity
Journal: Scientific American
Date published: May, 25 2006
No comments:
Post a Comment