Maternal effect dominant embryonic arrest

Maternal effect

A maternal effect is a situation where the phenotype of an organism is determined not only by the environment it experiences and its genotype, but also by the environment and phenotype of its mother...

dominant embryonic arrest (Medea) is a selfish gene

Intragenomic conflict

The selfish gene theory postulates that natural selection will increase the frequency of those genes whose phenotypic effects ensure their successful replication...

composed of a toxin and an antidote. A mother carrying Medea will express

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

the toxin in her germline, killing her progeny. If the children also carry Medea, they produce copies of the antidote, saving their lives. Therefore, if a mother has one Medea allele and one non-Medea allele, half of her children will inherit Medea and survive while the other half will inherit the non-Medea allele and die (unless they receive Medea from their father).

Medea's selfish behavior gives it a selective advantage over normal genes. If introduced into a population at sufficiently high levels, the Medea gene will spread, replacing entire populations of normal flies with flies carrying Medea. Because of this, Medea has been proposed as a way of genetically modifying

Genetic engineering

Genetic engineering, also called genetic modification, is the direct human manipulation of an organism's genome using modern DNA technology. It involves the introduction of foreign DNA or synthetic genes into the organism of interest...

insect populations. By linking the Medea construct to a gene of interest - for instance, a gene conferring resistance to malaria - Medeas unique dynamics could be exploited to drive both genes into a population. These findings have dramatic implications for the control of insect-borne diseases such as malaria

Malaria

Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...

and dengue fever

Dengue fever

Dengue fever , also known as breakbone fever, is an infectious tropical disease caused by the dengue virus. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles...

Construction of Medea

Medea is the only selfish gene

Intragenomic conflict

The selfish gene theory postulates that natural selection will increase the frequency of those genes whose phenotypic effects ensure their successful replication...

that has been synthesized in the lab and tested in the fruit fly Drosophila melanogaster

Drosophila melanogaster

Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...

. The toxin was a microRNA that blocked the expression of myd88, a gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

vital for embryonic development in insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s. The antidote was an extra copy of myd88. The offspring receiving the extra copy of myd88 survived and hatched, while those without the extra copy died. In lab trials where 25% of the original members were homozygous for Medea, the gene spread to the entire population within 10 to 12 generations.

Etymology

Medea was named for the Greek mythological

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

figure of Medea

Medea

Medea is a woman in Greek mythology. She was the daughter of King Aeëtes of Colchis, niece of Circe, granddaughter of the sun god Helios, and later wife to the hero Jason, with whom she had two children, Mermeros and Pheres. In Euripides's play Medea, Jason leaves Medea when Creon, king of...

, who killed her children when her husband left her for another woman. The reference is appropriate since Medea kills all progeny that do not carry it.

Construction of Medea

Etymology

Further reading