Sex-Reversal of Male Mice

Summary:
         Recent studies at the Institute of Molecular Biology (IMB) have shown that with just the deletion of one gene, the gender of a male mice can be completely reversed. This doesn't mean that the mouse's Y chromosome will convert into an X chromosome, (in fact, the Y chromosome will remain there) but rather that this specific gene, called Gadd45g, is necessary for the development of male sex organs. Gadd45g regulates signals that control Sry, a master regulator of male sex development. For male sex organs to develop properly, it is necessary for an abundance of Sry, but without Gadd45g, there will be a lack of Sry as well.    
         Research done at IMB by Professor Christof Niehrs has shown that with the deletion of this gene and a lack of Sry, the external genitalia of the mouse will be altered to be identical to that of a female mouse. With the deletion of Gadd45g, there is also a change in the internal reproductive organs within the mouse, making them those of a female mouse as well. While completing his experiment, Niehrs was puzzled why he got only females after breeding Gadd45g mutant mice, until he discovered that in some of the female mice, a Y chromosome was still present. From his observations, he was able to conclude that this gene is essential for the development of male sex organs. His research has since then been published in the  journal: Developmental Cell.

Relevance: 
          This news article is relevant to our current studies because it relates to our unit on genetics. We discussed how mutations in genes can have very disastrous effects or no effect at all. One of the mutations we have talked about is deletions. This article shows how the deletion of one gene, Gadd45g, can result in a very extreme change. This article also portrays how one gene can control another gene by helping it function. This story also has a relation to our unit on heredity because in this case, Gadd45g is a male gene inherited on the Y chromosome from father to son, but with the deletion of this gene, which could occur from a mishap in meiosis, a mouse's gender can be completely reversed.

November 29, 2012  - Research by Christof Niehrs of the Institute of Molecular Biology
http://www.medicalnewstoday.com/releases/253293.php