A Mothers Protection: Inherited Fertility in Fruit Fly
Clinging to the DNA that we inherit from our parents are a variety of Proteins and molecules that come as part of the package.
These Proteins and molecules are termed Epigenetic Material and act, in a sense, as gene regulators. They can decide which gene expresses at what time and have a role in the orginisation of the genome. One of their functions is known to be the chemical suppression or limitation of gene expression.
It is known that particular epigenetic marks will act on specific genes, inhibiting the expression of that gene and rendering it, in effect, obsolete.
It is believed that enzymes facilitate the interaction of epigenetic material with DNA and mark the exact location that the interaction will take place. It was also believed that RNA served only as a guide to the enzymes but was not itself a carrier of epigenetic materials...until now.
Researchers at the Cold Spring Harbor Laboratory (CSHL) have recently found that RNA in fruit fly eggs also carry Epigenetic information which is inherited from the mother. This material has been termed piRNA and is believed to protect the fruit fly against certain Transposons.
What are Transposons??
Transposons are small fragments of DNA which can jump from one chromosome to another causing breakages in the genome and mutations. They were discovered by Barbara Mclintock in the 1940's and are believed to be involved in a variety of diseases including cancer.
A Transposon interrupting the DNA sequence
How Do These piRNA Ensure Fertility?
It is believed that Fruit fly DNA contains a Transposon that jumps about and causes Sterility. The piRNA is crucially involved in inhibiting this Transposon, ensuring that chromosomes responsible for reproduction continue to function and the Fruit fly remains fertile.
This piRNA has been found only in fruit fly sex cells and is the first time epigenetic material has been known to be inherited in this manner.
The leader of the study,Professor Gregory J. Hannon stated that with this study they've "effectively doubled the number of mechanisms by which epigenetic information is known to be inherited".
It is not known whether this mechanism of inherited protection is present in other animals, but researchers speculate that it is probably the case.
This opens up an interesting area in inherited DNA protection against diseases and bacteria with transposable mechanisms.
Articles Referenced
Unknown,2008, "Epigenetic Traits Inherited Not Only Through DNA", Redorbit: 18 March 2009. http://www.redorbit.com/news/health/1603130/epigenetic_traits_ inherited_not_only_through_dna/
Unknown."Transposons",18 March 2009. http://www.bioinformatics.nl/webportal/background/transposonsinfo.html
